Hot runner cooling jacket for PET products with diamond texture

Abstract

This utility model relates to the field of injection mold technology and discloses a hot runner cooling water jacket suitable for PET products with diamond-patterned textures. It includes a front template, with the water jacket body embedded inside the front template, and a mold cavity inside the front template. A cold gate is designed between the product's glue position and the valve needle. The cooling water path sequentially passes through a first-stage cooling water cavity and a second-stage cooling water cavity to form an independent cooling circuit, achieving rapid cooling of the water jacket body. This keeps the temperature in the local area around the cold runner between 15-20°C, preventing heat from the hot nozzle and valve needle from being transferred to the product area. Simultaneously, because the diameter of the second section of the water jacket body is very small, cooling water can be designed on both sides of the cold gate, allowing the temperature at the hot nozzle end and the product cavity end to rapidly cool from a molding temperature above 280°C to below 80°C, thus avoiding the crystallization temperature range of PET material and rapidly cooling to the ideal mold cavity temperature of around 20°C, thereby ensuring good product transparency.

Description

Technical Field

[0001] This utility model belongs to the field of injection mold technology, specifically a hot runner cooling water jacket suitable for PET products with diamond-shaped texture. Background Technology

[0002] Large transparent parts inside refrigerators, such as bottle holders, drawers, and trays, are mostly made of transparent PS (polystyrene), a rigid but brittle material. Under stress, it exhibits brittle fracture and becomes brittle at low temperatures, especially below -30°C, when it becomes extremely fragile and prone to cracking upon impact.

[0003] PET (polyethylene terephthalate) plastic, as a semi-crystalline plastic, has become the preferred replacement material for PS due to its advantages such as high transparency, good toughness and low-temperature resistance, smooth and delicate feel, and low price compared to similar materials. Especially in the injection mold industry, its application in large transparent parts such as refrigerator drawers, bottle holders, and trays has moved from the exploratory development stage to the application stage.

[0004] However, the following two problems have been troubling the mold industry; 1. Due to the semi-crystalline nature of PET material: For large transparent PET parts, the injection molding temperature is generally between 280-310℃. Within this temperature range, PET material maintains good fluidity and molding performance, thus ensuring the transparency and quality of the product. However, PET crystallizes between 120-220℃. Within this temperature range, PET material crystallizes, affecting its transparency and physical properties. For refrigerator parts, the biggest problem is avoiding crystallization. Therefore, the hot runner section of the mold needs to be maintained above 280℃ for injection molding, while the plastic temperature inside the mold cavity needs to be kept below 120℃ to prevent crystallization. Thus, the temperature of the mold gate and the product cavity typically needs to be below 80℃ to ensure that the PET material inside the cavity is not in a crystalline state. Furthermore, PET material is prone to internal stress during cooling. To avoid shrinkage cavities, cracks, and other defects, mold temperature directly affects the crystallization and cooling efficiency of the product. Therefore, it needs to be cooled as soon as possible after injection molding. To ensure good product transparency and a short injection molding production cycle, after repeated production verification, it is recommended that the mold temperature be controlled between 15-20℃ for best results. One of the problems we need to solve is how to rapidly cool the molten plastic injected from the hot runner at 280-310℃ to the temperature of 15-20℃ inside the mold cavity.

[0005] Large transparent refrigerator-style containers such as bottle holders, drawers, and trays are generally large in size. To facilitate filling, most similar products made of non-PET materials require a design similar to...Figure 4 The hot runner shown has a direct injection method at the bottom. This structure, where the hot nozzle is too close to the product and the valve needle is in direct contact with the product, cannot meet the requirement of 280-310℃ for the inner part of the hot runner of PET material while the product part is below 80℃ to prevent crystallization.

[0006] 2. The bottom of most products needs to be designed as follows: Figure 5 The diamond-shaped texture shown has unevenness, which causes vertical and irregular vertical surfaces to be generated in the mold cavity at the gate. These surfaces seriously affect the smooth flow of plastic, thus causing excessive local shear heat and material sticking. Utility Model Content

[0007] In view of the above situation and to overcome the defects of the prior art, this utility model provides a hot runner cooling water jacket suitable for PET products with diamond-shaped textures, which effectively solves the problems mentioned in the background.

[0008] To achieve the above objectives, this utility model provides the following technical solution: a hot runner cooling water jacket suitable for PET products with diamond-shaped textures, wherein a water jacket body is embedded inside the front template, a mold cavity is provided inside the front template, the mold cavity is located below the water jacket body, the product glue position is located at the lower end of the water jacket body, a cooling water channel is provided on the outside of the water jacket body, the cooling water channel and the outer wall of the water jacket body form a first-stage cooling water cavity and a second-stage cooling water cavity, a hot nozzle is provided inside the water jacket body, and a valve needle is provided inside the hot nozzle; The water jacket body includes a bucket-shaped body, a first-stage cooling water chamber located on the outer wall of the bucket-shaped body, a first sealing plane connected to the upper end of the bucket-shaped body, a second sealing plane connected to the lower end of the bucket-shaped body, a conical sprue sleeve connected to the lower end of the second sealing plane, a second-stage cooling water chamber located on the outer wall of the conical sprue sleeve, a cold gate opened inside the conical sprue sleeve, and an outwardly convex arc at the end of the cold gate.

[0009] Preferably, a first sealing ring is embedded in the lower end face of the first sealing plane, a second sealing ring is embedded in the lower end face of the second sealing plane, and a third sealing ring is embedded in the stepped end face of the conical gate sleeve.

[0010] Preferably, the first sealing ring, the second sealing ring and the third sealing ring are each provided with a corresponding mounting groove.

[0011] Preferably, the water jacket body is made of beryllium copper.

[0012] Compared with the prior art, the beneficial effects of this utility model are: 1. This utility model designs a cold gate between the product's glue position and the valve needle, forming a first-stage annular cooling water chamber between the first and second sealing rings, and a second-stage cooling water chamber between the second and third sealing rings. The cooling water path sequentially passes through the first and second-stage cooling water chambers to form an independent cooling circuit, achieving rapid cooling of the water jacket body. The temperature and cooling speed of the cold runner can be controlled by adjusting the water temperature and flow rate in the circuit using an external chiller. This keeps the temperature of the local area around the cold runner between 15-20℃, preventing the heat from the hot nozzle and valve needle from being transferred to the product area. Furthermore, because the diameter of the second-stage water chamber in the water jacket body is very small, cooling water can be designed on both sides of the cold gate, allowing the temperature of the hot nozzle end and the product cavity end to rapidly cool from a molding temperature above 280℃ to below 80℃, thus avoiding the crystallization temperature range of PET material and rapidly cooling to the ideal mold cavity temperature of around 20℃, thereby ensuring good product transparency. 2. To avoid the impact of the sharp edges formed between the diamond pattern and the conical cold gate on product flow, this new design adds an outwardly convex arc structure at the end of the cold gate. Since the conical gate sleeve is a circular structure, the cold gate and the outwardly convex arc can be polished to a mirror finish through rotary polishing, thereby reducing the large friction and shear heat generated during plastic filling and avoiding the problem of material sticking caused by local overheating of the cold gate. Attached Figure Description

[0013] The accompanying drawings are provided to further understand the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation thereof.

[0014] In the attached diagram: Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is a schematic diagram of the structure of the water jacket body of this utility model; Figure 3 This is a schematic diagram of the convex arc at the end of the cold gate of this utility model; Figure 4 Schematic diagram of a valve needle type hot runner direct-entry adhesive for PS material; Figure 5 This is a schematic diagram of the diamond pattern on the bottom of the product. In the diagram: 1. Front template; 2. Mold cavity; 3. Water jacket body; 301. Bucket-shaped body; 302. First sealing plane; 303. Second sealing plane; 304. Conical sprue sleeve; 305. Cold gate; 306. Outwardly convex arc; 4. Product glue position; 5. Cooling water channel; 6. First-stage cooling water cavity; 7. Second-stage cooling water cavity; 8. Hot nozzle; 9. Valve needle; 10. First sealing ring; 11. Second sealing ring; 12. Third sealing ring. Detailed Implementation

[0015] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the protection scope of the present utility model.

[0016] Example 1, by Figures 1-3 As shown, the front template 1 of this utility model has a water jacket body 3 embedded inside, the front template 1 has a mold cavity 2 inside, the mold cavity 2 is located below the water jacket body 3, the product glue position 4 is located at the lower end of the water jacket body 3, the water jacket body 3 has a cooling water channel 5 on the outside, the cooling water channel 5 and the outer wall of the water jacket body 3 form a first-stage cooling water cavity 6 and a second-stage cooling water cavity 7, the water jacket body 3 has a hot nozzle 8 inside, and the hot nozzle 8 has a valve needle 9 inside. The water jacket body 3 includes a bucket-shaped body 301, a first-stage cooling water cavity 6 located on the outer wall of the bucket-shaped body 301, a first sealing plane 302 connected to the upper end of the bucket-shaped body 301, a second sealing plane 303 connected to the lower end of the bucket-shaped body 301, a conical sprue sleeve 304 connected to the lower end of the second sealing plane 303, a second-stage cooling water cavity 7 located on the outer wall of the conical sprue sleeve 304, a cold gate 305 opened inside the conical sprue sleeve 304, and an outwardly convex arc 306 at the end of the cold gate 305.

[0017] A first sealing ring 10 is embedded in the lower end face of the first sealing plane 302, a second sealing ring 11 is embedded in the lower end face of the second sealing plane 303, and a third sealing ring 12 is embedded in the stepped end face of the conical gate sleeve 304.

[0018] The first sealing ring 10, the second sealing ring 11 and the third sealing ring 12 are all provided with corresponding mounting grooves. Preferably, the mounting groove has an inward octagonal cross section, which can prevent the sealing ring from falling off during the assembly process and play a role in preventing the sealing ring from falling off.

[0019] The water jacket body 3 is made of beryllium copper, which has higher thermal conductivity.

[0020] This device designs a cold gate 305 between the product glue position 4 and the valve needle 9, forming an annular first-stage cooling water chamber 6 between the first sealing ring 10 and the second sealing ring 11, and a second-stage cooling water chamber 7 between the second sealing ring 11 and the third sealing ring 12. The cooling water channel 5 achieves cooling of the water jacket body 3 through the cooling circuit formed by the first-stage cooling water chamber 6 and the second-stage cooling water chamber 7. The temperature and cooling speed of the cold runner can be controlled by adjusting the water temperature and flow rate in the circuit using an external chiller. This keeps the temperature of the local area around the cold runner between 15-20℃, preventing the heat from the hot nozzle 8 and the valve needle 9 from being transferred to the product area. At the same time, because the diameter of the second section of the water chamber in the water jacket body 3 is very small, cooling water can be designed on both sides of the cold gate 305, thereby rapidly cooling the temperature of the hot nozzle end and the product cavity end from the molding temperature above 280℃ to below 80℃, thus avoiding the crystallization temperature range of PET material and rapidly cooling to the ideal mold temperature of about 20℃, thus ensuring good transparency of the product.

[0021] To avoid the impact of the sharp edges formed between the diamond pattern and the tapered cold gate 305 on product flow, a convex arc 306 structure is added to the end of the cold gate 305. Since the tapered gate sleeve 304 is a circular structure, the cold gate 305 and the convex arc 306 can be polished to a mirror finish by rotary polishing. This reduces the large friction and shear heat generated during plastic filling, reduces the sticking force of the cold gate 305, and avoids the problem of material sticking caused by local overheating of the cold gate 305.

[0022] Working principle: During the injection molding process, the high-temperature molten PET plastic enters the mold cavity 2 through the hot nozzle 8. The valve needle 9 inside the hot nozzle 8 is used to control the flow of the molten plastic to ensure that it is smoothly filled into the mold cavity 2. Due to the characteristics of PET material, the temperature needs to be reduced rapidly after injection molding to avoid crystallization and to prevent stress from being generated inside the product. To achieve this goal, the device is designed with an independent cooling water channel 5. The cooling water channel 5 surrounds the outside of the water jacket body 3 and forms a first-stage cooling water cavity 6 and a second-stage cooling water cavity 7 with the outer wall of the water jacket body 3. The first-stage cooling water cavity 6 is located on the outer wall of the bucket-shaped body 301, and the second-stage cooling water cavity 7 is located on the outer wall of the conical gating sleeve 304. Cooling water enters from the cooling water channel 5 and flows through the first-stage cooling water cavity 6 and the second-stage cooling water cavity 7 in sequence to form a complete cooling circuit. By adjusting the temperature and flow rate of the cooling water using an external chiller, the cooling speed and the temperature of the water jacket body 3 can be precisely controlled. The circulation of the cooling water removes the heat transferred by the hot nozzle 8 and valve needle 9, ensuring that the temperature around the cold flow channel is maintained between 15-20℃. This temperature control method effectively prevents the PET material from crystallizing during the cooling process, thereby ensuring the transparency and surface quality of the product. The bottom of the product sprue 4 is designed with a diamond-shaped texture. The unevenness of these textures will cause the mold cavity at the gate to produce a vertical and irregular surface, which will affect the flow of plastic. To solve this problem, this device is designed with an outwardly convex arc 306 structure at the end of the cold gate 305. The cold gate 305 is located inside the conical gate sleeve 304. The convex arc 306 at its end can effectively reduce the friction and shear heat of the plastic during the filling process. Since the conical gate sleeve 304 is a circular structure, the cold gate 305 and the convex arc 306 can be polished to a mirror level by rotational polishing. This design not only reduces the resistance of the plastic during the filling process, but also reduces the sticking force of the cold gate 305, avoiding the sticking problem caused by local overheating. To ensure the sealing and cooling effect of the cooling water circuit 5, the device has a first sealing ring 10 embedded on the lower end face of the first sealing plane 302, a second sealing ring 11 embedded on the lower end face of the second sealing plane 303, and a third sealing ring 12 embedded on the stepped end face of the conical sprue sleeve 304. Corresponding mounting grooves are provided at the mounting points of these sealing rings to ensure that the sealing rings are firmly installed and have reliable sealing performance. The setting of the sealing rings effectively prevents the leakage of cooling water and ensures the normal operation of the cooling water circuit 5.

Claims

1. A hot runner cooling jacket suitable for PET products with diamond texture, comprising a front mold plate (1), characterized in that: The front template (1) is fitted with a water jacket body (3), and the front template (1) is provided with a mold cavity (2). The mold cavity (2) is located below the water jacket body (3). The product glue position (4) is located at the lower end of the water jacket body (3). The water jacket body (3) is provided with a cooling water channel (5) on the outside. The cooling water channel (5) and the outer wall of the water jacket body (3) form a first-stage cooling water cavity (6) and a second-stage cooling water cavity (7). The water jacket body (3) is provided with a hot nozzle (8) inside. The hot nozzle (8) is provided with a valve needle (9) inside. The water jacket body (3) includes a bucket-shaped body (301), a first-stage cooling water chamber (6) located on the outer wall of the bucket-shaped body (301), a first sealing plane (302) at the upper end of the bucket-shaped body (301), a second sealing plane (303) at the lower end of the bucket-shaped body (301), a conical sprue sleeve (304) connected to the lower end of the second sealing plane (303), a second-stage cooling water chamber (7) located on the outer wall of the conical sprue sleeve (304), a cold gate (305) opened inside the conical sprue sleeve (304), and an outwardly convex arc (306) at the end of the cold gate (305).

2. A hot runner cooling water jacket for PET products with a diamond-patterned texture according to claim 1, characterized in that: The lower end face of the first sealing plane (302) is fitted with a first sealing ring (10), the lower end face of the second sealing plane (303) is fitted with a second sealing ring (11), and the stepped end face of the conical sprue sleeve (304) is fitted with a third sealing ring (12).

3. A hot runner cooling water jacket for PET products with a diamond-patterned texture according to claim 2, characterized in that: The first sealing ring (10), the second sealing ring (11) and the third sealing ring (12) are all provided with corresponding mounting grooves.

4. A hot runner cooling water jacket suitable for PET products with diamond-patterned texture according to claim 1, characterized in that: The water jacket body (3) is made of beryllium copper.

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