Injection molding equipment and production process of polyurethane conveyor belt

Abstract

The application discloses an injection molding equipment and production process of a polyurethane conveyor belt, and belongs to the injection molding technical field. In order to solve the problems of low bonding strength and poor production flexibility of the existing continuous lamination process, the application provides a segmented injection molding scheme. The equipment comprises a rack, a two-way movable upper mold and a lower mold, the mold cavity of the equipment is sequentially provided with a main molding area and a transition cooling area with a size smaller than the main molding area; the equipment is further provided with a hot runner shunt system and a downstream traction device. The production process realizes the circulation of "injection-molding-opening mold-drawing-remodeling", uses the rear end surface of the molded conveyor belt as the front end sealing surface of the next injection, preheats the rear end surface to realize seamless welding, and meanwhile, the transition cooling area micro-interference clamps the molded section to resist the injection pressure. The application realizes high-pressure injection and seamless welding, significantly improves the bonding strength of the conveyor belt and the core, and provides the possibility for flexible customized production.

Description

Technical Field

[0001] This invention relates to an injection molding equipment and production process for polyurethane conveyor belts, belonging to the field of injection molding technology. Background Technology

[0002] Polyurethane (PU) conveyor belts play an indispensable role in industries with stringent requirements for cleanliness, durability, and reliability, such as food processing, precision logistics sorting, electronics assembly, and tobacco, thanks to their superior abrasion resistance, excellent oil and chemical resistance, and potential to meet hygiene standards.

[0003] Currently, the mainstream production process in this field is continuous extrusion lamination. This method plasticizes PU into a film using an extruder, which is then hot-pressed with polyester, nylon fabric, or steel cord core as the reinforcing layer in a double-belt press or calender. While this process achieves efficient continuous production, its underlying technical principle—relying on heat and low to medium pressure to physically "bond" the PU layer to the fabric surface—indicates inherent and insurmountable technical bottlenecks.

[0004] 1. Limited interfacial bonding strength: The lamination process involves relatively low pressure, making it difficult for the PU layer to penetrate deeply into the fabric fiber bundles, and even more difficult to form a strong mechanical coating and interlocking of the independent rope core. This "adhesive" rather than "coating" bonding method results in the peel strength between the cover layer and the skeleton layer becoming a performance weakness of the product. Under high-frequency bending, lateral impact, or harsh chemical environments, delamination failure is prone to occur, significantly shortening the service life of the conveyor belt.

[0005] 2. Severe lack of production flexibility: Once a continuous production line is started, the material formula, color, thickness, and surface structure of the entire conveyor belt roll are fixed. For small-batch, diversified customized production, this results in lengthy equipment cleaning and material change times, and significant material waste, failing to meet the modern manufacturing industry's demand for flexible production with integrated functions and rapid iteration. For example, achieving hardness segmentation between wear-resistant and flexible zones on the same conveyor belt, integrating anti-static functional zones, or changing the color of different sections are impossible using traditional processes.

[0006] 3. Poor compatibility with high-performance fiber core skeletons: As conveyor belts develop towards higher strength and lower elongation, high-performance fiber cores such as aramid are being introduced as skeletons. These cores have dense surfaces, resulting in poor wettability and adhesion to PU. Traditional lamination processes struggle to form a robust, defect-free coating on their surface, limiting the development of high-performance conveyor belts.

[0007] Therefore, there is an urgent need in the field for a production method that can change the bonding mechanism between the PU layer and the skeleton layer, upgrading "surface bonding" to "three-dimensional coating", while breaking the rigid constraints of continuous production. This invention is an innovative solution proposed in this context. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide an injection molding equipment and production process for polyurethane conveyor belts. The aim is to achieve seamless production of conveyor belts through segmented injection molding, significantly improve the bonding strength between the cover layer and the rope core, and provide high production flexibility.

[0009] To achieve the above objectives, the present invention provides an injection molding apparatus for a polyurethane conveyor belt, comprising:

[0010] A frame; a mold, the mold comprising an upper mold and a lower mold that are movable relative to each other, both of the upper and lower molds being movably connected to the frame, the upper and lower molds defining a mold cavity for forming a conveyor belt after being closed; the mold cavity having a main forming zone and a transition cooling zone sequentially along the length of the conveyor belt, the mold cavity size of the transition cooling zone being smaller than the mold cavity size of the main forming zone; a hot runner distribution system for injecting molten polyurethane material into the main forming zone; a traction device, located downstream of the mold, for step-by-step traction of the formed conveyor belt along its length in the mold-open state; the equipment is configured such that, after a section of the conveyor belt has been injection molded and tractioned by the traction device, the rear end face of the formed section of the conveyor belt serves as the front end sealing face of the main forming zone during the next mold closing.

[0011] The frame includes a base and a beam plate; it also includes a liftable upper mold base and a lower mold base, the upper mold is fixed to the lower end face of the upper mold base, and the lower mold is fixed to the upper end face of the lower mold base; the equipment also includes an upper mold closing cylinder and a lower mold closing cylinder for driving the upper mold base and the lower mold base to lift and lower respectively.

[0012] It also includes an independently movable upper rear mold and a lower rear mold, which are located at the front end of the upper mold and the lower mold, and are used to seal the front end of the mold cavity during initial injection molding.

[0013] The injection molding equipment for polyurethane conveyor belts also includes a labyrinth sealing sleeve set on the mold for sealing the rope core passing through the mold in the mold-closed state.

[0014] Injection molding equipment for polyurethane conveyor belts also includes an integrated venting-demolding system, which includes:

[0015] Several microporous inserts are embedded in the mold cavity surfaces of the upper and lower molds; an air collection cavity is sealed on the back of the upper and lower molds and communicates with the several microporous inserts; a three-way solenoid valve has three ports connected to the air collection cavity, the outside atmosphere, and an air compressor as an air source, respectively; the three-way solenoid valve connects the air collection cavity to the outside atmosphere for exhaust during injection molding, and connects the air compressor to the air collection cavity for blowing air to assist demolding during mold opening.

[0016] The injection molding equipment for polyurethane conveyor belts also includes a zoned temperature control system, which includes: a liquid flow channel, disposed within the upper and lower molds, for heating and cooling the main molding zone and the transition cooling zone; and an electric heating tube, disposed between the main molding zone and the transition cooling zone within the mold, for heating the rear end face of the molded conveyor belt during injection molding.

[0017] The hot runner distribution system includes a melt distribution seat fixedly installed on one side of the lower mold. The melt distribution seat is provided with a main hot runner and a hot runner manifold connecting the main hot runner with multiple gates in the main forming area.

[0018] Furthermore, the present invention also provides a matching injection molding production process for polyurethane conveyor belts, comprising the following steps:

[0019] a) Initial injection: The rope core passes through the mold; the upper and lower molds are driven to close, and the upper and lower rear sealing molds are driven to close; molten polyurethane material is injected into the main molding zone and the transition cooling zone through the hot runner distribution system, and after pressure holding and cooling, the initial section conveyor belt is formed;

[0020] b) Mold opening: Drive the upper rear sealing mold and the lower rear sealing mold to open, and drive the upper mold and the lower mold to open;

[0021] c) Traction: The initial section of the conveyor belt is pulled forward by a traction device for a preset length so that the rear end face of the initial section of the conveyor belt is located between the main forming zone and the transition cooling zone, while its rear section enters the transition cooling zone.

[0022] d) Re-closing the mold: Drive the upper mold and lower mold to close again (the upper rear sealing mold and lower rear sealing mold no longer close), so that the rear end face of the initial section conveyor belt is blocked between the main forming area and the transition cooling area, and the rear section is clamped by the transition cooling area.

[0023] e) Re-injection: Molten polyurethane material is re-injected through the hot runner distribution system to fuse it with the rear end face of the initial section conveyor belt, forming the extended section conveyor belt;

[0024] f) Cycle: Repeat steps b) to e) to produce a conveyor belt of the predetermined length.

[0025] The process includes a temperature control step after step d) and before step e): heating the rear end face of the formed conveyor belt through an electric heating tube located between the main forming zone and the transition cooling zone in the mold, heating the main forming zone through a liquid flow channel in the main forming zone, and cooling the transition cooling zone through a liquid flow channel in the transition cooling zone to prevent the formed part of the conveyor belt from melting.

[0026] In addition, during the injection process, air is vented through microporous inserts; during the mold opening process, compressed air is blown into the mold cavity through microporous inserts to assist in demolding.

[0027] The beneficial effects of the invention are:

[0028] A process of "intermittent injection and continuous output" has been adopted, resulting in improved performance and functionality.

[0029] 1. A qualitative leap in interfacial bonding strength: This invention uses injection pressures of up to tens of megapascals to forcefully inject PU melt into a closed mold cavity. This extremely high-kinetic-energy melt can thoroughly penetrate and wet the fiber bundles of the rope core, densely covering the independent rope core. This shift in bonding mechanism from "two-dimensional bonding" to "three-dimensional coating" means that the peel strength of the cover layer is no longer a weakness of the product, thereby improving the conveyor belt's exceptional durability and anti-delamination ability under harsh working conditions.

[0030] 2. Increased flexibility in conveyor belt customization: The segmented production method fundamentally eliminates the constraints of continuous processes. This invention allows for the programmed injection of PU materials with different properties into different sections of the same conveyor belt, such as manufacturing wear-resistant / flexible composite belts with varying hardness, visually identifiable belts with color partitions, or conductive / insulating belts with functional partitions. This production flexibility transforms conveyor belts from standardized consumables into highly customizable, functionally integrated precision components.

[0031] 3. Achieves high automation and quality stability throughout the entire process: This invention integrates key process nodes such as rope core sealing, efficient venting and active demolding, preheating of the interface between new and old materials, and seamless welding into a closed-loop controlled fully automated process through an integrated electromechanical, pneumatic, and hydraulic system. This not only significantly reduces manual intervention but also fundamentally ensures the high consistency and reliability of each molding stage and each welding process, guaranteeing the overall quality of the final product. Attached Figure Description

[0032] Figure 1 This is one of the perspective views of the overall structure of the present invention;

[0033] Figure 2 This is a front view of the overall structure of the present invention;

[0034] Figure 3This is the second perspective view of the overall structure of the present invention;

[0035] Figure 4 This is one of the schematic diagrams of the conveyor belt forming process (the rope core comes between the upper and lower molds);

[0036] Figure 5 This is the second schematic diagram of the conveyor belt forming process (the upper and lower molds and the upper and lower rear sealing molds are closed, and injection molding begins).

[0037] Figure 6 This is the third schematic diagram of the conveyor belt forming process (upper and lower molds and upper and lower rear mold sealing and opening).

[0038] Figure 7 This is the fourth schematic diagram of the conveyor belt forming process (the formed conveyor belt moves forward a distance equal to the length of one main forming zone).

[0039] Figure 8 This is the fifth schematic diagram of the conveyor belt forming process (the upper and lower molds close again and injection molding begins, and the upper and lower molds are then sealed and no longer closed).

[0040] Figure 9 This is the sixth schematic diagram of the conveyor belt forming process (opening of the upper and lower molds).

[0041] Figure 10 This is the seventh schematic diagram of the conveyor belt forming process (the already formed conveyor belt moves forward another distance equal to the length of the main forming zone).

[0042] Figure 11 This is the eighth schematic diagram of the conveyor belt forming process (forming a conveyor belt of a certain length);

[0043] Figure 12 This is one of the three-dimensional structural diagrams of an injection molding equipment (front view);

[0044] Figure 13 This is the second three-dimensional structural diagram of the injection molding equipment (back side).

[0045] Figure 14 This is the third three-dimensional structural diagram of the injection molding equipment (showing the melt distribution seat and labyrinth sealing sleeve structure).

[0046] Figure 15 yes Figure 14 A magnified view of part A in the middle;

[0047] Figure 16 yes Figure 14 A magnified view of part B in the middle;

[0048] Figure 17 yes Figure 14 A magnified view of part C in the middle;

[0049] Figure 18 This is the fourth three-dimensional structural diagram of the injection molding equipment (showing the fit between the rear mold and the upper and lower molds).

[0050] Figure 19 yes Figure 18 A magnified view of part D in the middle;

[0051] Figure 20 yes Figure 18 A magnified view of part E in the middle;

[0052] Figure 21 This is the fifth three-dimensional structural diagram of the injection molding equipment (showing the fit between the rear mold and the upper and lower molds).

[0053] Figure 22 yes Figure 21 A magnified view of part F in the middle;

[0054] Figure 23 yes Figure 21 A magnified view of the central G region;

[0055] Figure 24 This is one of the sectional views of the mold part of the injection molding equipment;

[0056] Figure 25 This is the second sectional view of the mold part of the injection molding equipment;

[0057] Figure 26 yes Figure 25 A magnified view of the middle H section;

[0058] Figure 27 This is the third sectional view of the mold part of the injection molding equipment.

[0059] In the diagram: 1. Injection molding equipment; 2. Injection machine; 3. Mold temperature controller; 4. Injection nozzle; 5. Rope core; 6. Conveyor belt; 7. Upper mold; 8. Lower mold; 9. Main molding zone; 10. Transition cooling zone; 11. Melt distribution seat; 12. Hot runner bushing; 13. Micro-perforated insert; 14. Upper rear mold seal; 15. Lower rear mold seal; 16. Air compressor; 17. Upper mold closing cylinder; 18. Beam plate; 19. Vertical column 20. Upper mold base; 21. Labyrinth sealing sleeve; 22. Lower mold base; 23. Base; 24. Lower mold closing cylinder; 25. Upper mold sealing cylinder; 26. Lower mold sealing cylinder; 27. Electric heating tube; 28. Liquid runner connector; 29. ​​Main hot runner; 30. Hot runner manifold; 31. Gate; 32. Positioning hole; 33. Positioning pin; 34. Gas collection chamber; 35. Three-way solenoid valve; 36. Liquid runner. Detailed Implementation

[0060] The present invention will be further described below with reference to specific embodiments.

[0061] The description of the present invention is merely a structural or even functional description of the embodiments, and the scope of the present invention is not limited by the embodiments described herein.

[0062] like Figures 1-27 As shown, this embodiment is achieved through the following technical solution:

[0063] This invention provides a polyurethane conveyor belt production line, mainly comprising an injection molding machine 1, an injection molding machine 2, and a mold temperature controller 3. The injection molding machine 2 is a standard horizontal injection molding machine, whose injection nozzle 4 can move back and forth under the drive of the injection seat. The mold temperature controller 3 is used for precise temperature control of the mold. The core of this invention lies in the unique structure and production process of the injection molding machine 1.

[0064] The injection molding equipment 1 has a gantry-type frame, including a base 23, a top beam 18, and a column 19 connecting the two. Between the base 23 and the beam 18, there are an upper mold base 20 and a lower mold base 22, which can move up and down along the column 19. The upper mold 7 is fixed to the lower end face of the upper mold base 20, and the lower mold 8 is fixed to the upper end face of the lower mold base 22. An upper mold closing cylinder 17 is mounted on the beam 18, and its piston rod is connected to the upper mold base 20 to drive the upper mold 7 to rise and fall. A lower mold closing cylinder 24 is mounted inside the base 23, and its piston rod is connected to the lower mold base 22 to drive the lower mold 8 to rise and fall. During mold closing, the upper mold 7 descends, and the lower mold 8 rises, closing at the parting surface in the center of the equipment.

[0065] The mold cavity formed after the upper mold 7 and lower mold 8 are closed is divided into a main molding zone 9 (rear half) and a transition cooling zone 10 (front half) along the traction direction of the conveyor belt 6 (from back to front). The main molding zone 9 is the core area for PU material injection and filling. The mold cavity size of the transition cooling zone 10 is designed to be smaller than that of the main molding zone 9, with a dimensional difference at the micrometer level. This design utilizes the thermal expansion and contraction characteristics of PU. When the conveyor belt section, which has just been molded in the main molding zone 9 and is still at a high temperature, is pulled to the transition cooling zone 10, it will form an interference fit with the inner wall of the mold cavity in this area, thereby generating huge frictional force and playing a firm clamping role to resist the huge pressure transmitted from the rear end face during the next injection. At the same time, this area performs secondary cooling and shaping of the conveyor belt 6 to ensure its dimensional stability.

[0066] The hot runner distribution system is integrated into the lower mold 8. A melt distribution seat 11 is fixedly installed on one side of the lower mold 8, and it rises and falls together with the lower mold 8. The melt distribution seat 11 has a main hot runner 29, and its inlet has a hot runner bushing 12 that connects with the injection nozzle 4 of the injection molding machine 2. The main hot runner 29 distributes the melt to multiple gates 31 evenly distributed along the length of the main molding zone 9 through the hot runner manifold 30, achieving uniform filling over a long distance. The gates 31 are preferably submarine gates, which can be automatically cut off when the mold is opened.

[0067] To achieve initial molding and effective sealing of the rope core 5, the equipment is equipped with independent rear sealing molds and rope core sealing structures. The upper rear sealing mold 14 and lower rear sealing mold 15 are independently installed at the front end of the mold, and are driven to rise and fall by the upper sealing mold cylinder 25 and lower sealing mold cylinder 26, respectively. They are only closed during the production of the first section of the conveyor belt, used to seal the front end of the mold cavity. Several semi-circular labyrinth sealing sleeves 21 are evenly distributed on the end parting surface of the mold and the parting surface of the rear sealing mold. When the upper and lower molds are closed, and when the upper and lower rear sealing molds are closed, they form a complete circular sealing channel, providing high-pressure sealing for the passing rope core 5, effectively preventing material leakage. To ensure precise positioning of the rear sealing mold and the mold, the rear sealing mold is equipped with conical positioning posts 33, and the mold has corresponding positioning holes 32.

[0068] To achieve efficient venting and reliable demolding, the equipment integrates a venting-demolding integrated system. Several microporous inserts 13 made of porous, breathable steel are embedded in the cavity surfaces of the upper mold 7 and lower mold 8. A sealed air collection chamber 34 on the back of each mold connects all the microporous inserts 13. A three-way solenoid valve 35 is connected to the back of the air collection chamber 34. During injection, the solenoid valve connects the air collection chamber 34 to the atmosphere, achieving passive venting; after mold opening, the solenoid valve switches, allowing compressed air from the air compressor 16 to enter the air collection chamber 34, which then blows air into the mold cavity through the microporous inserts 13, assisting in product demolding.

[0069] To achieve precise temperature control, both the upper mold 7 and the lower mold 8 are equipped with S-shaped liquid flow channels 36, which are connected to an external mold temperature controller 3 via side liquid flow channel connectors 28 for heating or forced cooling of the mold. The liquid flow channels 36 in the main molding zone 9 and the transition cooling zone 10 are separate and can be heated and cooled independently. In particular, an electric heating tube 27 is embedded between the main molding zone 9 and the transition cooling zone 10, at the point where the new and old materials fuse. This electric heating tube 27 is used to precisely preheat the rear end face of the molded conveyor belt 6 before the next injection, ensuring better fusion bonding between the new and old materials to form a seamless, high-strength connection.

[0070] This invention ingeniously solves two major challenges in intermittent molding. Mechanically, it utilizes the thermal shrinkage properties of PU to create a strong interference fit with the molded section through differences in mold cavity dimensions, providing mechanical support for subsequent injection and ensuring stability under high pressure. Thermally, it establishes a smooth temperature gradient from the main molding zone to the outside of the mold, performing secondary cooling and shaping of the product, effectively suppressing internal stress and ensuring excellent straightness and dimensional consistency of the conveyor belt.

[0071] The working principle and process flow of the present invention will be described in detail below with reference to the accompanying drawings.

[0072] Start-up and initial segment formation (reference) Figure 2 , Figure 4 , Figure 5 , Figure 12 , Figure 24 ):

[0073] Before production begins, multiple rope cores 5 (such as fabric rope cores, steel wire rope cores, etc.) are drawn out from the upstream unwinding device, pass through the combing device, and then pass through the front and rear ends of the injection molding equipment. Subsequently, the upper mold closing cylinder 17 and the lower mold closing cylinder 24 drive the upper mold 7 and the lower mold 8 to perform the main mold closing, and the upper mold sealing cylinder 25 and the lower mold sealing cylinder 26 drive the upper rear mold sealing cylinder 14 and the lower rear mold sealing cylinder 15 to also close, forming a closed mold cavity inside the mold for molding the first section of the conveyor belt. The injection seat of the injection machine 2 advances, causing the injection nozzle 4 to be high-pressure connected to the hot runner bushing 12. The mold temperature controller 3 has stabilized the liquid flow channel 36 of the mold at the preset process temperature, for example, 40-60°C. Subsequently, the injection machine 2 injects molten PU (temperature approximately 200-220°C) into the main molding zone 9 through the hot runner distribution system. During the injection process, the air in the mold cavity is discharged to the atmosphere through the microporous insert 13 and the three-way solenoid valve 35. After pressure holding and cooling, the PU solidifies, forming the first section of the conveyor belt.

[0074] Seamless welding and continuous production cycle (process illustration reference) Figures 6-11 ):

[0075] After the initial segment is formed, production enters an automated cycle:

[0076] 1. Mold opening and assisted demolding (reference) Figure 6 , Figure 24 The upper and lower molds are then sealed and opened sequentially. At this time, the three-way solenoid valve 35 switches, and compressed air from the air compressor 16 is blown in through the microporous insert 13, forming an air film on the conveyor belt and the mold surface, breaking the adsorption and assisting in smooth demolding.

[0077] 2. Traction and Positioning (Reference) Figure 7 , Figure 12 The remote servo traction device is activated, precisely pulling the formed conveyor belt 6 forward by the length of the main forming zone 9. After traction is completed, the physical position of the first section of the conveyor belt changes: its rear end face is precisely located between the main forming zone 9 and the transition cooling zone 10, while its rear half completely enters the transition cooling zone 10.

[0078] 3. Mold closing, clamping, and preheating (see reference) Figure 8 , Figure 12 , Figure 13 , Figure 27 The upper rear mold 14 and lower rear mold 15 remain open and do not participate in subsequent processes. The upper mold 7 and lower mold 8 close again. At this time:

[0079] Establishment of mechanical clamping: The conveyor belt, having just left the main molding zone 9 (temperature approximately 60°C), has a cross-sectional dimension larger due to thermal expansion than after further cooling and shrinkage in the transition cooling zone 10 (temperature approximately 40°C). Therefore, when clamped in this area, a micron-level interference fit is created between its surface and the inner wall of the mold cavity. Furthermore, due to the large contact area, this interference fit generates a large, uniformly distributed frictional clamping force, firmly fixing this section of the conveyor belt so that it can withstand the subsequent injection impact force.

[0080] Preparation of the weld interface: At the same time, the electric heating tube 27 located between the main forming zone 9 and the transition cooling zone 10 is activated to rapidly and precisely heat the cold end face of the first section of the conveyor belt in a non-contact manner, raising its surface temperature to an activation state close to the melting point (e.g., 150-170°C), creating the necessary temperature conditions for re-welding.

[0081] 4. Secondary Injection and Welding: After the end face is preheated and the mechanical clamping is stable, a second injection is performed. The high-temperature virgin PU material impacts the preheated end face of the old material, allowing for full diffusion, penetration, and re-entanglement at the interface. During the subsequent pressure holding and cooling process, a homogeneous weld zone with no physical interface and strength identical to the base material is formed.

[0082] 5. Repeated Cycle: By repeatedly performing the "mold opening and demolding" process... Figure 9 ) - Traction Positioning ( Figure 10 By following the steps of "molding, clamping and preheating - injection welding", a seamless polyurethane conveyor belt with theoretically unlimited length and highly uniform performance can be produced. Figure 11 ).

[0083] The above production process, through innovative equipment structure, cleverly transforms intermittent precision injection molding into continuous product output, thereby achieving performance and functionality that traditional processes cannot achieve.

[0084] Of course, the above description is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the embodiments of the present invention. The present invention is also not limited to the above examples, and all equivalent changes and improvements made by those skilled in the art within the scope of the present invention should fall within the patent coverage of the present invention.

Claims

1. An injection molding device for a polyurethane conveyor belt, characterized in that, include: The frame includes a base (23) and a beam plate (18); it also includes an upper mold base (20) and a lower mold base (22) for lifting, and an upper mold closing cylinder (17) and a lower mold closing cylinder (24) for driving the upper mold base (20) and the lower mold base (22) to lift. The mold includes an upper mold (7) and a lower mold (8) that move relative to each other. The upper mold (7) is fixed to the lower end face of the upper mold base (20), and the lower mold (8) is fixed to the upper end face of the lower mold base (22). After the upper mold (7) and the lower mold (8) are closed, a mold cavity for forming the conveyor belt (6) is defined. Independently movable upper rear sealing mold (14) and lower rear sealing mold (15), the upper rear sealing mold (14) and lower rear sealing mold (15) are arranged at the front end of the upper mold (7) and the lower mold (8) for sealing the front end of the mold cavity during initial injection molding; The mold cavity is provided with a main forming area (9) and a transition cooling area (10) in sequence along the length direction of the conveyor belt (6). The mold cavity size of the transition cooling area (10) is smaller than that of the main forming area (9). An electric heating tube (27) is provided between the main forming area (9) and the transition cooling area (10) in the mold, and is used to heat the rear end face of the formed conveyor belt (6) during injection molding. A hot runner distribution system is used to inject molten polyurethane material into the main molding zone (9). A traction device is located downstream of the mold and is used to perform step-by-step traction of the formed conveyor belt (6) along its length direction when the mold is open. It also includes a labyrinth sealing sleeve (21) set on the mold for sealing the rope core (5) passing through the mold in the mold closed state; The equipment is configured such that, after a section of conveyor belt (6) is injection molded and pulled by the traction device, the rear end face of the molded section of conveyor belt (6) serves as the front end sealing face of the main molding area (9) during the next mold closing.

2. The injection molding equipment for polyurethane conveyor belts according to claim 1, characterized in that, It also includes an integrated venting-demolding system, which comprises: Several micro-perforated inserts (13) are embedded in the mold cavity surfaces of the upper mold (7) and the lower mold (8); The gas collection cavity (34) is sealed on the back of the upper mold (7) and the lower mold (8) and communicates with the plurality of microporous inserts (13); The three-way solenoid valve (35) has three ports connected to the air collection chamber (34), the outside atmosphere and the air compressor (16) that serves as the air source, respectively. The three-way solenoid valve (35) connects the gas collection chamber (34) to the outside atmosphere during injection molding to exhaust gas, and connects the air compressor (16) to the gas collection chamber (34) during mold opening to blow air to assist demolding.

3. The injection molding equipment for polyurethane conveyor belts according to claim 1, characterized in that, It also includes a zoned temperature control system, which includes: Liquid flow channels (36) are provided in the upper mold (7) and lower mold (8) for heating and cooling the main forming zone (9) and the transition cooling zone (10).

4. The injection molding equipment for polyurethane conveyor belts according to claim 1, characterized in that, The hot runner distribution system includes a melt distribution seat (11) fixedly installed on one side of the lower mold (8). The melt distribution seat (11) is provided with a main hot runner (29) and a hot runner manifold (30) connecting the main hot runner (29) with multiple gates (31) in the main molding area (9).

5. An injection molding production process for a polyurethane conveyor belt that is配套 with the device according to any one of claims 1-4, characterized in that, Includes the following steps: a) Initial injection: The rope core (5) passes through the mold; the upper mold (7) and lower mold (8) are driven to close, and the upper rear sealing mold (14) and lower rear sealing mold (15) are driven to close; molten polyurethane material is injected into the main molding zone (9) and the transition cooling zone (10) through the hot runner diversion system, and the initial section conveyor belt is formed after pressure holding and cooling. b) Mold opening: drive the upper rear sealing mold (14) and the lower rear sealing mold (15) to open the mold, drive the upper mold (7) and the lower mold (8) to open the mold; c) Traction: The initial section conveyor belt is pulled forward by a traction device for a preset length so that the rear end face of the initial section conveyor belt is located between the main forming zone (9) and the transition cooling zone (10), while its rear section enters the transition cooling zone (10). d) Re-closing the mold: drive the upper mold (7) and lower mold (8) to close the mold again, so that the rear end face of the initial section conveyor belt is blocked between the main forming area (9) and the transition cooling area (10), and the rear section is clamped by the transition cooling area (10); e) Re-injection: Molten polyurethane material is re-injected through the hot runner distribution system to fuse it with the rear end face of the initial section conveyor belt, forming the extended section conveyor belt; f) Cycle: Repeat steps b) to e) to produce a conveyor belt of the predetermined length.

6. The injection molding production process for the polyurethane conveyor belt according to claim 5, characterized in that, After step d) and before step e), a temperature control step is also included: the rear end face of the formed conveyor belt is heated by an electric heating tube (27) set between the main forming zone (9) and the transition cooling zone (10) in the mold, the main forming zone (9) is heated by a liquid flow channel (36) in the main forming zone (9), and the transition cooling zone (10) is cooled by a liquid flow channel (36) in the transition cooling zone (10) to prevent the formed part of the conveyor belt from melting.

7. The injection molding production process for the polyurethane conveyor belt according to claim 5, characterized in that, Several micro-hole inserts (13) are embedded in the mold cavity surfaces of the upper mold (7) and the lower mold (8). During the injection process, air is vented through the micro-hole inserts (13). During the mold opening process, compressed air is blown into the mold cavity through the micro-hole inserts (13) to assist in demolding.

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