PET (Polyethylene Terephthalate) bottle preform injection molding mold

Abstract

The invention relates to the technical field of plastic processing, in particular to a PET bottle blank injection molding mold which comprises a front mold frame, multiple sets of mold core assemblies arranged on the front mold frame, a rear mold frame arranged on one side of the front mold frame and a core injection assembly arranged on the rear mold frame. The mold core assembly comprises a mold core pipe, a mold core seat, a shell, a mold cavity plate, a mold cavity pipe, a water injection port and a water outlet, and fan blades rotating in different directions are arranged in the mold cavity pipe, so that optimization can be performed according to cooling requirements of different parts of a bottle blank. For example, the fan blades at the bottle opening rotate clockwise, water flow is accelerated, heat is rapidly taken away, and rapid cooling is ensured; and the fan blades on the bottle body and the bottle bottom rotate anticlockwise, so that the water flow speed is reduced, and internal stress and deformation caused by too fast cooling are avoided.

Description

Technical Field

[0001] The invention relates to the technical field of plastic processing, in particular to a PET bottle preform injection molding die. Background Art

[0002] PET preform injection molding molds are high-precision molds used to produce PET preforms. Molten PET material is injected into the mold cavity, where it cools and solidifies to form the preform. The mold consists of a cavity, core, gating system, cooling system, ejection mechanism, and guide system to ensure precision and stability during the molding process.

[0003] PET (polyethylene terephthalate), as a typical crystalline plastic, possesses many properties, but also brings a series of production and processing challenges. PET has a distinct melting point, approximately between 250-267°C. In the solid state, its molecules are regularly arranged, which gives it high strength and tensile strength. However, this characteristic causes a series of problems during the melting and solidification processes. PET has a large change in specific volume when melted, easily shrinks after solidification, and internal stress is difficult to release, which directly leads to opacity of the finished product. During the molding process, PET has poor heat dissipation performance. If it cannot be effectively cooled per unit time, PET will become semi-crystallized or crystallized, and then turn white and brittle. The material's toughness decreases, the transparency deteriorates, the viscosity value decreases, and the tensile strength and impact resistance of the preform will also decrease accordingly.

[0004] In addition to the aforementioned molding issues, fatigue fracture and oxidation of the mold cavity during the injection molding of PET preforms are also closely related to cooling. The spiral cooling groove milled on the outer wall of the mold cavity has a stepped corner near the bottom of the mold cavity, followed by a circular groove parallel to the bottom of the mold cavity. This design allows the cooling water to evenly cool the mold cavity and the preform. However, due to the excessive number of corners in the cooling groove, there are problems such as stress concentration and insufficient strength. The mold cavity repeatedly experiences heating and cooling during the injection molding process. This thermal stress cycle can cause microcracks on the mold cavity surface. Furthermore, the residual cooling water on the mold cavity accelerates the oxidation of the mold cavity material, reducing the surface hardness and toughness, further exacerbating the initiation and propagation of fatigue cracks. Moreover, insufficient cooling can also exacerbate oxidation on the mold cavity surface, especially in structurally weak areas such as the stepped cooling groove. This situation is more obvious.

[0005] Furthermore, in the injection molding process of PET bottle preforms, the reliability of the cooling device is crucial. In the existing technology, in order to further improve the fatigue life, it is necessary to increase the wall thickness of the mold cavity, that is, to reduce the groove depth, thereby increasing the strength of the mold cavity. However, compared with the actual production situation of the enterprise, it is necessary to significantly change the mold cavity plate, core plate and even the pouring system, which is relatively costly. This is a new idea for reference for enterprises, not the preferred structure for the final choice.

[0006] Therefore, a PET bottle preform injection molding die is proposed. Summary of the Invention

[0007] The purpose of the present invention is to provide a PET bottle preform injection molding mold, which uses the pressure of cooling water to make the fan blades turn differently, so that the cooling water flow rate in different areas of the corresponding bottle preform is also different, and after cooling is completed, uses a spring to rotate the fan blades in the opposite direction to blow away the residual cooling water, thereby achieving the effects of improving cooling efficiency, reducing mold cavity oxidation and extending mold life.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A PET bottle preform injection molding mold, comprising a front mold frame, multiple core mold assemblies arranged on the front mold frame, a rear mold frame arranged on one side of the front mold frame, and a core injection assembly arranged on the rear mold frame, wherein the core mold assembly comprises a core tube, a core seat, an outer shell, a cavity plate, a cavity tube, a water inlet and a water outlet, wherein the core tube is arranged on the front mold frame, the core seat is arranged on the core tube, the outer shell is arranged on the front mold frame and connected to the core seat, the cavity plate is arranged on one side of the outer shell, the cavity tube is arranged on the cavity plate, and the The water inlet and the water outlet are respectively opened on the mold cavity tube, and a cavity is provided on the mold cavity tube. A transmission component is provided in the cavity, a linkage component is provided on the transmission component, and a fan blade is provided on the linkage component. The linkage component drives the fan blades to rotate after the bottle blank is cooled. Multiple groups of fan blades have different directions when rotating. The fan blades correspond to different areas of the mold cavity plate. The fan blades rotate in the opposite direction after the bottle blank finishes cooling. The fan blades change the water flow speed in different areas when the bottle blank is cooling and can also reduce the oxidation of the mold cavity plate after cooling is completed.

[0010] It can be seen that in the existing technology, the shape of PET bottle blanks is complex, and the thickness and structure of different parts (such as the bottle body, bottle mouth, bottle bottom, etc.) are different. Traditional cooling methods are difficult to achieve uniform cooling, which easily leads to defects such as warping and deformation of the bottle blanks during the cooling process, affecting product quality. In addition, the flow of cooling water in the mold cavity is in a series manner, that is, the temperature of the water entering the mold cavity can be guaranteed to be 8°C, but the temperature of the cooling water afterwards must be higher than 8°C, resulting in uneven cooling in the mold cavity and low cooling efficiency. The device cooperates with fan blades and transmission components. When the bottle blank is being cooled, cooling water enters the cavity through the water inlet and uses water pressure to drive the fan blades to rotate. During rotation, multiple groups of fan blades rotate in different directions in the mold cavity tube. The fan blades corresponding to the bottle mouth of the bottle blank rotate clockwise, and the fan blades corresponding to the bottle body and bottle bottom rotate counterclockwise. When the fan blades rotate clockwise, they accelerate the water flow in the mold cavity. On the contrary, when the fan blades rotate counterclockwise, they adsorb the water flow in the mold cavity. The adsorption force generated by the fan blades can slow down the flow rate of the water flow and take away some of the heat generated during the initial cooling of the water flow.

[0011] Preferably, the cavity includes a drainage channel, a baffle, a groove, multiple groups of cavities, and a circular hole. The drainage channel is opened on one side of the water inlet, and the water inlet is connected to the drainage channel. The baffle is arranged below one end of the water inlet, and the baffle is arranged inside the water inlet. One end of the drainage channel is connected to the cavity. The groove is opened above the drainage channel, and the transmission assembly is arranged in the groove. Multiple groups of cavities are arranged in a linear array below the groove, and the multiple groups of cavities are connected to each other. Multiple groups of circular holes are respectively opened at the bottom of the cavity. The baffle diverts part of the cooling water through the drainage channel into the cavity, and then the cooling water in the cavity flows out of the circular hole. Only the cavity connected to the drainage channel will pass through the cooling water.

[0012] Preferably, the transmission assembly includes multiple groups of gears and multiple groups of transmission wheels, the multiple groups of gears are arranged above the cavity and correspond to the center line of the cavity, the multiple groups of transmission wheels are arranged between two groups of gears, wherein two groups of gears in the multiple groups of gears are meshed with each other, and the remaining gears are respectively meshed with the transmission wheels. When one group of fan blades rotates, the fan blades are connected to the gears, and then under the meshing of the gears and the transmission wheels, the remaining gears all rotate, and there is no transmission wheel between the second and third groups of gears from left to right, and they are directly meshed with each other, so that the rotation directions of the first group of gears to the fifth group of gears starting from the left are clockwise, clockwise, counterclockwise, counterclockwise and counterclockwise respectively, and the different rotation directions of the fan blades result in different effects.

[0013] Preferably, the plurality of circular holes are arranged and distributed outwardly in a group proximal to the drainage channel, while the remaining plurality of circular holes are arranged vertically and perpendicular to the horizontal plane. The wind direction generated by the group of circular holes proximal to the drainage channel also expands outward, rather than directly impacting the cooling water, thereby accelerating the water flow rate.

[0014] Preferably, the linkage assembly includes a screw, a stopper, and a spring. The screw is disposed within the cavity and connected to the gear. The stopper is disposed on the screw, and the diameter of the stopper is the same as the diameter of the cavity. The spring is disposed below the stopper, and the fan blades are disposed at the bottom of the screw. The water pressure of the cooling water impacts the stopper, which is pressed downward by gravity. Since the stopper is threadedly connected to the screw, when the stopper descends, it drives the screw to rotate, and when the screw rotates, it drives the fan blades to rotate.

[0015] Preferably, the fan blade is further provided with a chute, the end of the spring is arranged in the chute, and the diameter of the chute is the same as the diameter of the spring. In order not to affect the arrangement of the spring when the fan blade rotates, a chute is provided above the spring, and the end of the spring slides in the chute.

[0016] Preferably, a cooling groove is provided on the mold cavity tube, the cooling groove includes a spiral groove and a stepped groove, the cooling groove is provided at the end of the mold cavity tube, the stepped groove is connected to the cooling groove, and the stepped groove is provided with a rounded corner.

[0017] Preferably, the fillet on the stepped groove is set directly below the circular hole. It can be seen that due to the excessive number of corners in the cooling groove, there are problems such as stress concentration and insufficient strength. The mold cavity repeatedly undergoes heating and cooling during the injection molding process. This thermal stress cycle will cause microcracks on the mold cavity surface, and the residual cooling water on the mold cavity accelerates the oxidation of the mold cavity material, reduces the surface hardness and toughness, and further aggravates the initiation and expansion of fatigue cracks. When the cooling water is cooled, the fan blades begin to rotate in the opposite direction under the action of the spring, and the initial adsorption force is converted into a blowing force, so that the cooling water remaining on the fillet of the cooling groove can be blown away from the corner of the fillet, thereby reducing oxidation at the fillet and strengthening the toughness of the mold cavity tube.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. By installing fan blades rotating in different directions within the mold cavity, cooling can be optimized based on the cooling requirements of different parts of the preform. For example, the fan blades at the bottle mouth rotate clockwise, accelerating water flow and rapidly removing heat, ensuring rapid cooling. Meanwhile, the fan blades at the bottle body and bottom rotate counterclockwise, slowing water flow and preventing internal stress and deformation caused by excessive cooling. This design not only improves cooling efficiency but also effectively solves the problem of uneven cooling, significantly enhancing the molding quality of PET preforms.

[0020] 2. Microcracks are easily formed at the corners of the cooling trough due to stress concentration and residual cooling water, which accelerates oxidation of the cavity material and reduces surface hardness and toughness. To address this problem, the present invention uses spring force to reverse the fan blades after the cooling water is completely cooled, blowing away the residual cooling water at the rounded corners of the cooling trough, reducing oxidation, enhancing the toughness of the cavity tube, and extending the service life of the mold.

[0021] 3. The design of the drainage channel and circular holes optimizes the flow of cooling water within the mold cavity. A group of circular holes near the drainage channel are arranged and distributed outward, directing the wind outward rather than directly opposing the cooling water. This accelerates the water flow without compromising the cooling effect. This design further optimizes the cooling process, ensuring a more uniform and efficient flow of cooling water within the mold cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the overall structure of a PET bottle preform injection molding mold of the present invention;

[0023] Figure 2Schematic diagram of the cross-sectional structure of the core assembly of the present invention;

[0024] Figure 3 It is a structural schematic diagram of the transmission assembly of the present invention;

[0025] Figure 4 For the present invention Figure 3 A magnified schematic diagram of point A;

[0026] Figure 5 This is a schematic diagram of the overall structure of a PET bottle preform injection molding mold from another angle of the present invention;

[0027] Figure 6 Schematic diagram of the structure of the core assembly of the present invention;

[0028] Figure 7 It is a structural schematic diagram of the cooling tank of the present invention;

[0029] Figure 8 It is a cross-sectional plan view of the core assembly of the present invention.

[0030] In the figure: 1. Front mold frame; 2. Core assembly; 3. Rear mold frame; 4. Core injection assembly; 21. Core tube; 22. Core seat; 23. Shell; 24. Cavity plate; 25. Cavity tube; 26. Water inlet; 27. Water outlet; 5. Cavity; 6. Transmission assembly; 7. Linkage assembly; 8. Fan blade; 51. Drainage channel; 52. Baffle; 53. Groove; 54. Cavity; 55. Circular hole; 61. Gear; 62. Transmission wheel; 71. Screw; 72. Limit block; 73. Spring; 81. Slide; 211. Cooling trough; 2111. Spiral groove; 2112. Stepped groove; 2113. Rounded corner. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] See also Figures 1 to 8 The present invention provides a PET bottle preform injection molding mold, the technical solution is as follows:

[0033] See also Figure 1 、 Figure 2 and Figure 5 and 6A PET preform injection molding mold includes a front mold frame 1, multiple core mold assemblies 2 arranged on the front mold frame 1, a rear mold frame 3 arranged on one side of the front mold frame 1, and a core injection assembly 4 arranged on the rear mold frame 3. The core mold assembly 2 includes a core tube 21, a core seat 22, a shell 23, a cavity plate 24, a cavity tube 25, a water injection port 26 and a water outlet 27. The core tube 21 is arranged on the front mold frame 1, the core seat 22 is arranged on the core tube 21, the shell 23 is arranged on the front mold frame 1 and connected to the core seat 22, the cavity plate 24 is arranged on one side of the shell 23, and the cavity tube 25 is arranged On the mold cavity plate 24, the water injection port 26 and the water outlet 27 are respectively opened on the mold cavity tube 25, and a cavity 5 is provided on the mold cavity tube 25. A transmission component 6 is provided in the cavity 5, a linkage component 7 is provided on the transmission component 6, and a fan blade 8 is provided on the linkage component 7. The linkage component 7 drives the fan blade 8 to rotate after the bottle blank is cooled. The multiple groups of fan blades 8 have different directions when rotating. The fan blades 8 correspond to different areas of the mold cavity plate 24. The fan blades 8 rotate in the opposite direction after the bottle blank finishes cooling. The fan blades 8 change the water flow speed in different areas when the bottle blank is cooling and can also reduce the oxidation of the mold cavity plate 24 after cooling is completed.

[0034] The front mold frame 1 and the rear mold frame 3 are first closed to form a sealed mold cavity. The injection molding machine then heats the PET material to a molten state and injects it into the core assembly 2 via the core injection assembly 4. The molten PET material rapidly fills the mold cavity under high pressure, forming the initial shape of the preform. After injection, the injection molding machine maintains a certain pressure to compensate for material shrinkage during cooling. Simultaneously, the cooling system begins to operate, circulating cooling water through the cooling water channels, rapidly removing heat from the mold cavity and cooling the preform to solidify. Controlling the cooling rate is critical and needs to be optimized based on the wall thickness and shape of the preform to ensure uniform cooling and avoid internal stress and deformation. Once the preform has cooled and solidified, the injection molding machine's mold opening mechanism separates the front mold frame 1 and the rear mold frame 3, and the ejection system ejects the formed preform from the mold.

[0035] In existing technology, PET preforms have complex shapes, with varying thicknesses and structures in different areas (such as the body, mouth, and bottom). This makes it difficult to achieve uniform cooling using traditional cooling methods. This can easily lead to defects such as warping and deformation during the cooling process, impacting product quality. Furthermore, cooling water typically flows through the mold cavity in a serial manner. While the cooling water can be kept at a low temperature (e.g., 8°C) upon entering the mold cavity, its temperature inevitably rises as it flows, resulting in uneven cooling within the mold cavity and inefficient cooling.

[0036] To address these issues, the present invention utilizes fan blades 8 in conjunction with a transmission assembly 6. During preform cooling, cooling water enters the cavity 5 through the water inlet 26, driving the fan blades 8 to rotate using water pressure. During rotation, the first set of fan blades 8 drives the transmission assembly 6, causing multiple sets of fan blades 8 to rotate in different directions within the mold tube 25: the fan blades 8 corresponding to the preform's mouth rotate clockwise, while the fan blades 8 corresponding to the bottle body and base rotate counterclockwise. This is because the cooling rate at the mouth significantly impacts molding quality, and rapid cooling is typically required to ensure dimensional accuracy and a tight seal. Increasing the water flow rate in the cooling water channel can quickly reduce the temperature of the bottle mouth and shorten cooling time. The central region of the bottle body typically has thinner walls, and excessively rapid cooling can easily lead to increased internal stress, impacting the product's mechanical properties and transparency. Therefore, appropriately reducing the water flow rate ensures uniform cooling and reduces internal stress. Cooling the base region requires particular attention to prevent warping and deformation. Appropriately reducing the water flow rate ensures uniform cooling and avoids stress concentration caused by excessive cooling. When fan blades 8 rotate clockwise, they accelerate the water flow within the mold cavity, helping to quickly remove heat. Conversely, when fan blades 8 rotate counterclockwise, they act as an absorbent force on the water flow within the mold cavity, slowing the flow rate and removing some of the heat generated during the initial cooling process. This design not only improves cooling efficiency but also effectively solves the problem of uneven cooling, significantly enhancing the molding quality of PET preforms.

[0037] As an embodiment of the present invention, refer to Figure 2 The cavity 5 includes a drainage channel 51, a baffle 52, a groove 53, multiple groups of cavities 54, and a circular hole 55. The drainage channel 51 is opened on one side of the water inlet 26, and the water inlet 26 is connected to the drainage channel 51. The baffle 52 is arranged below one end of the water inlet 26 and is arranged inside the water inlet 26. One end of the drainage channel 51 is connected to the cavities 54. The groove 53 is opened above the drainage channel 51. The transmission assembly 6 is arranged in the groove 53. Multiple groups of cavities 54 are arranged in a linear array below the groove 53. The multiple groups of cavities 54 are interconnected. Multiple groups of circular holes 55 are respectively opened at the bottom of the cavities 54. The baffle 52 diverts part of the cooling water through the drainage channel 51 into the cavities 54. The cooling water in the cavities 54 then flows out of the circular holes 55. Only the cavities 54 connected to the drainage channel 51 will pass cooling water.

[0038] As an embodiment of the present invention, refer to Figures 2-4The transmission assembly 6 includes multiple groups of gears 61 and multiple groups of transmission wheels 62. The multiple groups of gears 61 are arranged above the cavity 54 and correspond to the center line of the cavity 54. The multiple groups of transmission wheels 62 are arranged between the two groups of gears 61, wherein two groups of gears 61 in the multiple groups of gears 61 are meshed with each other, and the remaining gears 61 are respectively meshed with the transmission wheels 62. When one group of fan blades 8 rotates, the fan blades 8 are connected to the gears 61. Then, under the meshing of the gears 61 and the transmission wheels 62, the remaining gears 61 all rotate, and there is no transmission wheel 62 between the second and third groups of gears 61 from left to right, and they are directly meshed with each other. Therefore, the rotation directions of the first group of gears 61 to the fifth group of gears 61 starting from the left are clockwise, clockwise, counterclockwise, counterclockwise and counterclockwise respectively. The different rotation directions of the fan blades 8 result in different effects.

[0039] As an embodiment of the present invention, refer to Figure 2 The multiple groups of circular holes 55 arranged and distributed outwardly near the drainage channel 51 are arranged and distributed, while the remaining multiple groups of circular holes 55 are vertically perpendicular to the horizontal plane. The wind direction generated by the group of circular holes 55 arranged and distributed outwardly near the drainage channel 51 also expands outward, rather than directly colliding with the cooling water. This can accelerate the flow rate of the water without affecting the cooling effect. From left to right, the first and second groups of circular holes 55 rotate clockwise, so the cooling water is pushed by the wind and its flow rate is accelerated.

[0040] As an embodiment of the present invention, refer to Figures 2-3 The linkage assembly 7 includes a screw 71, a stopper 72, and a spring 73. The screw 71 is disposed in the cavity 54 and connected to the gear 61. The stopper 72 is disposed on the screw 71. The diameter of the stopper 72 is the same as that of the cavity 54. The spring 73 is disposed below the stopper 72. The fan blade 8 is disposed at the bottom of the screw 71. The water pressure of the cooling water impacts the stopper 72, which is pressed downward by gravity. Since the stopper 72 is threadedly connected to the screw 71, when the stopper 72 descends, it drives the screw 71 to rotate. The rotation of the screw 71 drives the fan blade 8 to rotate.

[0041] As an embodiment of the present invention, refer to Figure 4 The fan blade 8 is also provided with a chute 81, and the end of the spring 73 is arranged in the chute 81. The diameter of the chute 81 is the same as the diameter of the spring 73. In order not to affect the arrangement of the spring 73 when the fan blade 8 rotates, the chute 81 is provided above the spring 73, and the end of the spring 73 slides in the chute 81.

[0042] As an embodiment of the present invention, refer to Figure 7A cooling groove 211 is provided on the mold cavity tube 25. The cooling groove 211 includes a spiral groove 2111 and a stepped groove 2112. The cooling groove 211 is provided at the end of the mold cavity tube 25. The stepped groove 2112 is connected to the cooling groove 211. A rounded corner 2113 is provided on the stepped groove 2112.

[0043] As an embodiment of the present invention, refer to Figures 7-8 The fillet 2113 on the stepped groove 2112 is set just below the circular hole 55. It can be seen that due to the excessive number of corners in the cooling groove 211, there are problems such as stress concentration and insufficient strength. The mold cavity undergoes repeated heating and cooling during the injection molding process. This thermal stress cycle will cause microcracks on the surface of the mold cavity, and the residual cooling water on the mold cavity accelerates the oxidation of the mold cavity material, reduces the surface hardness and toughness, and further aggravates the initiation and expansion of fatigue cracks. When the cooling water is cooled, the fan blade 8 starts to rotate in the opposite direction under the action of the spring 73, and the initial adsorption force is converted into a blowing force, so that the cooling water remaining on the fillet 2113 on the cooling groove 211 can be blown away from the corner of the fillet 2113, thereby reducing the oxidation at the fillet 2113 and strengthening the toughness of the mold cavity tube 25.

[0044] Working principle: The front mold frame 1 and the rear mold frame 3 are first closed to form a sealed cavity. Then, the injection molding machine heats the PET material to a molten state and injects it into the core assembly 2 through the core injection assembly 4. The molten PET material quickly fills the cavity under high pressure to form the initial shape of the preform. After the injection is completed, the injection molding machine maintains a certain pressure to compensate for the shrinkage of the material during the cooling process. At the same time, the cooling system starts to work, and cooling water enters the cavity 5 in the cavity tube 25 through the water injection port 26. The water pressure of the cooling water is used to drive the limit block 72 in the cavity 5 to press down. Since the limit block 72 is threadedly connected to the screw 71, when the limit block 72 descends, it drives the screw 71 to rotate. After the screw 71 rotates, it drives the fan blades 8 to rotate, and then drives the fan blades 8 to rotate. Due to the arrangement of the gear 61 on the screw 71, multiple groups of fan blades 8 rotate in different directions in the cavity tube 25;

[0045] The fan blades 8 corresponding to the bottle mouth rotate clockwise, while those corresponding to the bottle body and bottom rotate counterclockwise. This design is based on the cooling requirements of different parts of the bottle. The cooling rate of the bottle mouth has a significant impact on molding quality, and rapid cooling is generally required to ensure dimensional accuracy and sealing. Therefore, increasing the water flow rate in the cooling water channel can quickly reduce the temperature of the bottle mouth and shorten the cooling time. The central area of ​​the bottle body is generally thinner, and excessively rapid cooling can easily lead to increased internal stress, affecting the mechanical properties and transparency of the product. Therefore, appropriately reducing the water flow rate can ensure uniform cooling and reduce internal stress. The cooling of the bottle base requires special attention to prevent warping and deformation. Appropriately reducing the water flow rate ensures uniform cooling and avoids stress concentration caused by excessive cooling.

[0046] In summary, when fan blades 8 rotate clockwise, they accelerate the water flow within the mold cavity, helping to quickly remove heat. Conversely, when fan blades 8 rotate counterclockwise, they absorb the water flow within the mold cavity, slowing its velocity and removing some of the heat generated during the initial cooling process. This design not only improves cooling efficiency but also effectively resolves the problem of uneven cooling, significantly enhancing the molding quality of PET preforms.

[0047] During the cooling process, the cooling water in the cavity 5 enters the chamber 54 through the drainage channel 51 and flows out through the circular holes 55. The circular holes 55 in the group near the drainage channel 51 are arranged and distributed outward, generating wind that also expands outward rather than directly impacting the cooling water. This accelerates the flow of the water without affecting the cooling effect. From left to right, the first and second groups of circular holes 55 rotate clockwise, and the cooling water is accelerated by the thrust of the wind.

[0048] Since the cooling groove 211 has too many corners, there are problems such as stress concentration and insufficient strength. The mold cavity repeatedly experiences heating and cooling during the injection molding process. This thermal stress cycle will cause microcracks on the mold cavity surface, and the residual cooling water on the mold cavity accelerates the oxidation of the mold cavity material, reduces the surface hardness and toughness, and further aggravates the initiation and expansion of fatigue cracks. In order to solve this problem, after the cooling water is cooled, the fan blade 8 begins to rotate in the opposite direction under the action of the spring 73, and the initial adsorption force is converted into a blowing force, so that the cooling water remaining on the fillet 2113 on the cooling groove 211 can be blown away from the corner of the fillet 2113, thereby reducing oxidation at the fillet 2113 and enhancing the toughness of the mold cavity tube 25.

[0049] When the preform cools and solidifies, the mold opening mechanism of the injection molding machine separates the front mold frame 1 and the rear mold frame 3, and the ejection system pushes the molded preform out of the mold, completing the entire injection molding process.

[0050] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A PET bottle preform injection molding mold, comprising a front mold frame (1), multiple groups of core components (2), a rear mold frame (3), and a core injection component (4), wherein the core component (2) comprises a core tube (21), a core seat (22), an outer shell (23), a cavity plate (24), a cavity tube (25), a water injection port (26), and a water outlet (27), wherein the core tube (21) is arranged on the front mold frame (1), the core seat (22) is arranged on the core tube (21), the outer shell (23) is arranged on the front mold frame (1) and connected to the core seat (22), the cavity plate (24) is arranged on one side of the outer shell (23), the cavity tube (25) is arranged on the cavity plate (24), and the water injection port (26) and the water outlet (27) are respectively opened on the cavity tube (25), characterized in that: The cavity tube (25) is provided with a cavity (5), a transmission assembly (6) is provided in the cavity (5), a linkage assembly (7) is provided on the transmission assembly (6), and a fan blade (8) is provided on the linkage assembly (7). The linkage assembly (7) drives the fan blade (8) to rotate after the preform is cooled. The plurality of groups of fan blades (8) rotate in different directions and correspond to different areas of the cavity plate (24). The fan blades (8) rotate in the opposite direction after the preform finishes cooling. The fan blades (8) change the water flow speed in different areas when the preform is cooled.

2. The PET preform injection molding mold according to claim 1, characterized in that: The cavity (5) comprises a drainage channel (51), a baffle (52), a groove (53), a plurality of groups of cavities (54) and a circular hole (55); the drainage channel (51) is opened on one side of the water injection port (26); the water injection port (26) is connected to the drainage channel (51); the baffle (52) is arranged below one end of the water injection port (26); the baffle (52) is arranged in the water injection port (26); one end of the drainage channel (51) is connected to the cavities (54); the groove (53) is opened above the drainage channel (51); the transmission assembly (6) is arranged in the groove (53); a plurality of groups of the cavities (54) are arranged in a linear array below the groove (53); the plurality of groups of the cavities (54) are connected to each other; a plurality of groups of circular holes (55) are provided and are respectively opened at the bottom of the cavities (54).

3. The PET preform injection molding mold according to claim 2, characterized in that: The transmission assembly (6) comprises a plurality of gear groups (61) and a plurality of transmission wheels (62), wherein the plurality of gear groups (61) are arranged above the cavity (54) and correspond to the center line of the cavity (54), and the plurality of transmission wheels (62) are arranged between two gear groups (61), wherein two gear groups (61) among the plurality of gear groups (61) are meshed with each other, and the remaining gears (61) are respectively meshed with the transmission wheels (62).

4. The PET preform injection molding mold according to claim 3, characterized in that: A group of the plurality of circular holes (55) close to the drainage channel (51) is arranged and distributed outwardly, and the remaining plurality of circular holes (55) are in a vertical state perpendicular to the horizontal plane.

5. A PET bottle preform injection molding mold according to claim 3 or 4, characterized in that: The linkage assembly (7) comprises a screw (71), a limit block (72) and a spring (73); the screw (71) is arranged in the cavity (54) and connected to the gear (61); the limit block (72) is arranged on the screw (71); the diameter of the limit block (72) is the same as the inner diameter of the cavity (54); the spring (73) is arranged below the limit block (72); and the fan blade (8) is arranged at the bottom of the screw (71).

6. The PET preform injection molding mold according to claim 5, characterized in that: The fan blade (8) is also provided with a sliding groove (81), and the end of the spring (73) is arranged in the sliding groove (81). The diameter of the sliding groove (81) is the same as the diameter of the spring (73).

7. The PET preform injection molding mold according to claim 6, characterized in that: The mold cavity tube (25) is provided with a cooling groove (211), the cooling groove (211) comprising a spiral groove (2111) and a stepped groove (2112), the cooling groove (211) being arranged at the end of the mold cavity tube (25), the stepped groove (2112) being connected to the cooling groove (211), and the stepped groove (2112) being provided with a rounded corner (2113).

8. The PET preform injection molding mold according to claim 7, characterized in that: The rounded corner (2113) on the stepped groove (2112) is arranged directly below the circular hole (55).

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