A thermoforming apparatus and process
By using a PET injection molding process with a circular sheet structure and a thermoforming device, the problems of high energy consumption and complex processes in the production of PET plastic cups have been solved, achieving low-cost and high-efficiency production and reducing waste and mold maintenance difficulties.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI KEMING INJECTION SYST TECH CO LTD
- Filing Date
- 2026-05-13
- Publication Date
- 2026-07-14
AI Technical Summary
The existing PET plastic cup production process suffers from high energy consumption, complex processes, and additional waste, especially in the processes of heating the sheet and stamping and cutting, which waste energy and resources.
The injection molding process using PET raw materials with a circular sheet structure, combined with a dedicated thermoforming device, directly forms plastic cups through blow molding, avoiding the steps of extruding sheets and stamping. The shaping is achieved using a mold sleeve and airflow channels, simplifying the process and reducing energy consumption.
It reduced production costs and energy consumption, simplified the process flow, improved product quality and production efficiency, reduced waste generation, and lowered the difficulty and cost of mold maintenance.
Smart Images
Figure CN122379005A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of plastic cup production technology, and in particular to a thermoforming apparatus and process. Background Technology
[0002] PET plastic cups are made of polyethylene terephthalate (PET), featuring high transparency that clearly showcases the layers of beverages, enhancing visual appeal. They are highly resistant to low temperatures, remaining relatively unaffected by deformation in temperatures ranging from room temperature to 5°C, and offer excellent impact resistance, making them durable and resistant to breakage. The material meets international food contact standards, effectively blocking moisture and external odors, preserving the original flavor of the beverage. Furthermore, PET cups are recyclable and produce only a small amount of harmless gas when incinerated, demonstrating outstanding environmental performance, making them an ideal choice for ready-to-drink beverages such as cold drinks and juices.
[0003] Current PET plastic cup production requires first extruding plastic granules into sheets and then winding them up. During unwinding, the sheets are heated and softened, and then the cups are thermoformed by passing them through rows of molds. After forming, the material at the edge of the cup needs to be punched off and then crushed and recycled. During the heating of the sheet, the energy consumed in heating the material at the edge of the cup is completely wasted. Moreover, the punching and crushing recycling processes after forming are not only complex but also generate additional energy consumption, which is not conducive to reducing production costs. Summary of the Invention
[0004] To reduce the energy consumption in the production of PET plastic cups, this application provides a thermoforming apparatus and process.
[0005] The thermoforming apparatus and process provided in this application adopt the following technical solution: A thermoforming process, comprising: Raw material drying: Dehumidify and dry the PET raw materials; Injection molding: PET raw materials are injection molded into a circular sheet structure using an injection molding machine and then cooled; Cup body forming: The circular sheet-shaped PET semi-finished product is heated, blow-molded through a molding die, and then cooled and shaped.
[0006] By adopting the above technical solution, during the injection molding process, the PET raw material is injection molded into a circular sheet structure, which is close to the diameter of the cup to be produced. There is no need to extrude the sheet, the injection volume is smaller, and there is no need to use a special sheet injection molding machine, resulting in lower production costs. Moreover, the circular sheet structure does not generate waste at the cup rim after molding, and there is no extra energy consumption from heating waste. There is no need for stamping and subsequent waste recycling, which can reduce energy consumption. Furthermore, the molding process is all done individually, without the need for blow molding of a row of cups on the sheet, which reduces the size of the mold and thus reduces the requirements for mold precision, making the production process simpler.
[0007] Preferably, in the raw material drying step, the proportion of recycled material does not exceed 25%, a dehumidifying dryer is used, the drying temperature is 150-170℃, the drying time is 3-4 hours, and the moisture content after drying is controlled to be below 0.005%. If the moisture content exceeds the standard, the drying time is extended. In the injection molding process, the temperature of the barrel is controlled at 240-260℃ in the feeding zone, 260-280℃ in the melting zone, and 270-280℃ in the nozzle zone. The melt thermocouple is used for real-time monitoring, and the temperature fluctuation must be ≤±3℃. The injection pressure is 80-120MPa, the holding pressure is 50%-70% of the injection pressure, and the holding time is 5-15 seconds. In the cup forming process, the heating temperature of the round sheet PET semi-finished product is 100-120℃, the mold temperature is 10-30℃, the holding time is 5-10 seconds, the cooling water temperature is 10-15℃, and the cooling time is 5-10 seconds.
[0008] By adopting the above technical solutions, in the raw material drying step, a drying temperature of 150-170℃ ensures deep dehumidification. In the injection molding step, the temperature of the barrel in the feeding zone is controlled at 240-260℃ to prevent premature melting and feeding difficulties, while also avoiding excessive material residence time in the high-temperature zone. The melting zone is 260-280℃ to promote the homogenization of PET molecular chains and eliminate unmelted crystal nuclei. The nozzle zone is 270-280℃, and the melt temperature is controlled below 280℃, as temperatures exceeding 290℃ can easily cause thermal degradation. The holding time is 5-15 seconds to prevent shrinkage marks and improve dimensional stability. In the cup body molding step, the holding time is 5-10 seconds to ensure that the sheet material is fully cooled and shaped, avoiding shrinkage.
[0009] A thermoforming apparatus includes a lower mold and an upper mold. The lower mold has a first cavity, and a first mold sleeve is disposed within the first cavity. The inner side of the upper edge of the first mold sleeve has an inner rim for placing a plastic disc. Several circumferentially distributed first vent holes are formed at the bottom side of the first mold sleeve. A support member is disposed inside the first mold sleeve, and a first push rod is mounted below the lower mold. The output end of the first push rod is fixed to the bottom of the support member to control its vertical movement. A first airflow channel is formed on the side of the lower mold, communicating with the first cavity, and the first airflow channel is at the same height as the first vent holes. A second cavity aligned with the first cavity is formed on the upper mold. The upper mold has a second mold sleeve inside the second cavity. The top of the second mold sleeve has several circumferentially distributed second vent holes. The second mold sleeve has a forming sleeve inside, and the forming sleeve has a forming cavity inside. The lower edge of the forming sleeve is aligned with the inner edge of the first mold sleeve. The top of the side of the forming sleeve has several third vent holes aligned with the second vent holes. The side of the upper mold has a second airflow channel, which communicates with the second cavity and is at the same height as the second vent holes. The forming sleeve has an extrusion head inside, and the upper end of the upper mold is equipped with a second push rod. The output end of the second push rod is fixed to the upper end of the extrusion head to control the up and down movement of the extrusion head.
[0010] By adopting the above technical solution, after the PET disc is heated and softened, it is placed on the inner edge of the first mold sleeve. Its edge is supported by the inner edge and the middle is supported by the support member. Then, the upper mold presses down, pressing the lower edge of the forming sleeve onto the outer periphery of the PET disc. Then, the first airflow channel on the side of the lower mold injects extrusion gas, while the second airflow channel on the side of the upper mold extracts air, causing the middle of the PET disc to protrude upward. At the same time, the support member pushes upward. With the cooperation of both, the PET disc adheres to the inner wall of the forming sleeve, achieving the shaping effect. After cooling, the upper mold moves upward, and then gas is injected into the second airflow channel. At the same time, the second push rod drives the extrusion head to press down, removing the plastic cup from the forming sleeve. The thermoforming is completed. There is no need for stamping and cutting or waste recycling after forming. The process is simple and has low energy consumption.
[0011] Preferably, the upper mold has two symmetrically distributed lifting push rods fixed to its side end, and the lower mold has fixed blocks on both sides. The fixed blocks are located directly below the lifting push rods, and the output end of the lifting push rod is fixedly connected to the fixed block at the corresponding position. The lower mold has a C-shaped limit rod fixed to its side end, and the upper mold has a first limit switch and a second limit switch fixed to its side end. Both the first limit switch and the second limit switch are located inside the C-shaped limit rod.
[0012] By adopting the above technical solution, when the lifting push rod extends, it can drive the upper mold to move upward and separate from the lower mold. When the lifting push rod retracts, it can drive the upper mold to descend and achieve mold closing. At the same time, during the rising process, the upper end of the C-shaped limit rod can trigger the first limit switch to limit the rising distance of the upper mold. During the falling process, the lower end of the C-shaped limit rod can trigger the second limit switch to limit the falling distance of the upper mold, ensuring that the mold closing and mold separating processes are smooth.
[0013] Preferably, the outer side of the first mold sleeve is provided with a first cooling groove, and the outer side of the first mold sleeve is provided with three layers of sealing rings respectively located above the first cooling groove, between the first cooling groove and the first vent hole, and below the first vent hole. The side of the lower mold is provided with a through first cooling medium flow channel, and the first cooling medium flow channel is aligned with the first cooling groove. The outer side of the second mold sleeve is provided with a second cooling groove, and the outer side of the second mold sleeve is provided with three layers of sealing rings respectively located below the second cooling groove, between the second cooling groove and the second vent hole, and above the second vent hole. The side of the upper mold is provided with a through second cooling medium flow channel, and the second cooling medium flow channel is aligned with the second cooling groove.
[0014] By adopting the above technical solution, in the lower mold, the cooling medium is output from one end of the first cooling medium flow channel and the other end, flowing through the first cooling groove in the middle, which can cool the first mold sleeve. Moreover, under the action of the three-layer sealing ring, the cooling medium and the gas in the first airflow channel will not interfere with each other or leak out, making the use process more stable. In the upper mold, the cooling medium is output from one end of the second cooling medium flow channel and the other end, flowing through the second cooling groove in the middle, which can cool the second mold sleeve. The three-layer sealing ring on the second mold sleeve has the same function as the three-layer sealing ring on the first mold sleeve, ensuring stable and reliable use.
[0015] Preferably, a mounting plate is fixed to the side end of the lower mold, a clip is fixed to the upper side of the mounting plate, a base plate is slidably mounted on the clip, and a discharge port is opened on the base plate. The bottom of the base plate is flush with the upper surface of the lower mold, and an edge shell is fixed to the upper surface of the base plate. Two symmetrically distributed limiting protrusions are fixed to the inner side of the edge shell, and a pull plate is slidably mounted between the limiting protrusions and the base plate. An inclined slope is provided above the pull plate, and an inclined plate is provided above the edge shell. The inclined plate abuts against the lower edge and the upper surface of the inclined slope.
[0016] By adopting the above technical solution, the operation of directly placing the softened PET disc onto the inner edge of the first mold sleeve is difficult. First, the bottom plate is pulled outwards to completely detach it from the lower mold. Then, the softened PET disc is placed on the inclined plate, and the PET disc slides down the inclined plate onto the inclined surface. Next, the bottom plate is pushed towards the center of the lower mold, so that the inclined surface is directly above the first mold sleeve. Then, keeping the bottom plate still, the pull plate is pulled outwards. At this point, the PET disc will not move outwards due to the obstruction of the inclined plate. As the inclined surface retracts, the PET disc gradually falls onto the first mold sleeve. When the inclined surface is completely pulled out, the PET disc is successfully placed on the inner edge of the first mold sleeve. Then, the bottom plate is pulled outwards again to completely detach it from the lower mold without affecting mold closing. The entire placement process is smoother, the PET disc is placed more accurately, and there is no skewing, ensuring product quality.
[0017] Preferably, the upper end of the base plate is fixed with two symmetrically distributed limiting screws, and the outer side of the edge shell is fixed with two symmetrically distributed limiting protrusions.
[0018] By adopting the above technical solution, when the base plate is pulled outward, the limiting screw will block the side wall of the clamp, which will play a limiting role and prevent the base plate from being completely pulled out. When the base plate is pushed inward, when the limiting protrusion abuts against the clamp, the edge of the inclined surface is just aligned with the inner eaves of the first mold sleeve, which facilitates positioning.
[0019] Preferably, an electric heating plate is embedded below the inclined surface, and the inclined surface is made of metal. The upper surface of the inclined surface is coated with a polytetrafluoroethylene coating. A weight-reducing groove is formed on the upper surface of the pull-out plate, and a number of heat dissipation fins are provided in the weight-reducing groove.
[0020] By adopting the above technical solution, the electric heating plate can heat the inclined surface, preventing the PET disc from cooling down too early when it is placed in place. At the same time, the polytetrafluoroethylene coating can reduce the friction between the inclined surface and the PET disc, making it easier to unload the PET disc. The heat dissipation fins can improve the heat dissipation effect and prevent high-temperature burns from the other end of the pull-out plate.
[0021] Preferably, the lower surface of the inclined plate is rotatably provided with a rotating shaft, and both ends of the rotating shaft are rotatably connected to the edge housing. Both ends of the rotating shaft are fitted with torsion springs. A stop block is fixed on the inner side of the edge housing. One end of the torsion spring abuts against the stop block, and the other end abuts against the lower surface of the inclined plate.
[0022] By adopting the above technical solution, the lower end of the inclined plate is pressed against the inclined surface by the elastic force of the torsion spring, and the plate remains in a resisting state when the inclined surface is pulled outward, preventing the PET disc from moving outward and further preventing the inclined surface from causing the PET disc to shift.
[0023] In summary, this application includes at least one of the following beneficial technical effects: 1. During the injection molding process, PET raw materials are injection molded into a circular sheet structure, which is close to the diameter of the cup to be produced. There is no need to extrude the sheet, the injection volume is smaller, and there is no need to use a special sheet injection molding machine, resulting in lower production costs. Moreover, the circular sheet structure does not generate waste at the cup mouth after molding, and there is no extra energy consumption for heating waste. There is no need for stamping and subsequent waste recycling, which can reduce energy consumption. In addition, the molding process is all individual molding, without the need for blow molding of a row of cups on the sheet, which reduces the size of the mold and thus reduces the requirements for mold precision, making the production process simpler. 2. Using the inclined plate, base plate, and pull plate, first place the PET disc on the inclined plate. The PET disc slides down the inclined plate onto the inclined surface. Then, push the base plate down to the center of the mold so that the inclined surface is directly above the first mold sleeve. Then, keep the base plate still and pull the pull plate outward. At this time, the PET disc will not move outward due to the obstruction of the inclined plate. As the inclined surface is pulled back, the PET disc is gradually placed onto the first mold sleeve. The placement of the PET disc is more accurate and will not be skewed, thus ensuring product quality. 3. In this application, each plastic cup is produced using a separate molding die. When mass-producing plastic cups, multiple separate molding dies can be combined. If one of the combined molding dies has a slight deviation, only the plastic cups produced by that mold will have inconsistent thicknesses. The production precision of the plastic cups produced by the other molds will not be affected. However, in the existing special sheet injection molding machine, the mold can form dozens of plastic cups at once with a single press. When the precision of the mold has a slight deviation (such as uneven height at both ends of the mold), this slight deviation will be amplified, resulting in a large number of plastic cups with inconsistent thicknesses. 4. At the same time, when a slight deviation occurs in a dedicated sheet injection molding machine, the entire dedicated sheet injection molding machine needs to be disassembled and repaired, which is costly and difficult. When a slight deviation occurs in the mold of this application, only the mold needs to be disassembled and replaced, which greatly reduces the maintenance cost and difficulty. Attached Figure Description
[0024] Figure 1 This is an isometric schematic diagram illustrating the overall structure of this application; Figure 2 This is a schematic diagram illustrating the main structure of the mold in this application; Figure 3 This is a schematic diagram illustrating the internal structure of the first cavity, which is the main feature of this application. Figure 4 This is a schematic diagram illustrating the main structure of the mold in this application; Figure 5 This is a schematic diagram illustrating the internal structure of the second cavity, which is the main feature of this application. Figure 6 This is a schematic diagram illustrating the cross-sectional structure of the upper and lower molds, which is the main features of this application. Figure 7 This is a schematic diagram illustrating the inclined plate structure, which is the main feature of this application. Figure 8 This is a schematic diagram illustrating the bottom structure of the base plate, which is the main feature of this application. Figure 9 This is a schematic diagram illustrating the pull-out panel structure, which is the main feature of this application. Figure 10 This is a schematic diagram illustrating the inclined plate connection method, which is the main feature of this application.
[0025] Reference numerals: 1. Lower mold; 2. Upper mold; 3. First cavity; 4. First mold sleeve; 5. First vent hole; 6. Support component; 7. First push rod; 8. Second cavity; 9. Second mold sleeve; 10. Second vent hole; 11. Forming sleeve; 12. Third vent hole; 13. Second airflow channel; 14. Extrusion head; 15. Second push rod; 16. Lifting push rod; 17. Fixing block; 18. C-shaped limit rod; 19. First limit switch; 20. Second limit switch; 21. First cooling recess 21. Groove; 22. First cooling medium flow channel; 23. Second cooling groove; 24. Second cooling medium flow channel; 25. Mounting plate; 26. Base plate; 27. Edge shell; 28. Discharge port; 29. Limiting protrusion; 30. Pull-out plate; 31. Inclined slope; 32. Inclined plate; 33. Limiting screw; 34. Limiting protrusion; 35. Clip; 36. Electric heating plate; 37. Weight reduction groove; 38. Heat dissipation fins; 39. Rotating shaft; 40. Stop block; 41. Torsion spring; 42. First airflow channel. Detailed Implementation
[0026] The following is in conjunction with the appendix Figure 1 -Appendix Figure 10 This application will be described in further detail.
[0027] This application discloses a thermoforming apparatus and process.
[0028] Example 1: A thermoforming process, comprising: Raw material drying: Dehumidify and dry the PET raw materials, with the proportion of recycled materials not exceeding 25%. Use a dehumidifying dryer, with a drying temperature of 150-170℃ and a drying time of 3-4 hours. Control the moisture content after drying to be below 0.005%. If the moisture content exceeds the standard, extend the drying time. Injection molding: PET raw materials are injected into a circular sheet structure through an injection molding machine and cooled. The temperature of the barrel is controlled at 240-260℃ in the feeding zone, 260-280℃ in the melting zone, and 270-280℃ in the nozzle zone. The melt thermocouple is used for real-time monitoring. The temperature fluctuation must be ≤±3℃. The injection pressure is 80-120MPa, the holding pressure is 50%-70% of the injection pressure, and the holding time is 5-15 seconds. Cup body forming: The circular sheet-shaped PET semi-finished product is heated to 100-120℃, formed by molding, and then cooled and shaped. The mold temperature is 10-30℃, the holding time is 5-10 seconds, the cooling water temperature is 10-15℃, and the cooling time is 5-10 seconds.
[0029] In the raw material drying process, the drying temperature is set at 150-170℃. This temperature range effectively achieves deep dehumidification of the raw materials, ensuring that the moisture content meets the requirements for subsequent processing. In the injection molding process, precise temperature control is required for each area of the barrel: the feeding zone temperature is set at 240-260℃. This temperature range prevents premature melting of the raw material, avoiding feeding difficulties caused by poor melting conditions. Simultaneously, the residence time of the material in the high-temperature zone must be strictly controlled. The melting zone temperature is set at 260-280℃. Under this temperature condition, the PET molecular chains can be fully melted and homogenized, effectively eliminating unmelted crystal nuclei and improving the material's processing performance. The nozzle zone temperature is set at 270-280℃, and the melt temperature must be strictly controlled below 280℃, because when the temperature exceeds 290℃, PET material is prone to thermal degradation, affecting product quality. Furthermore, the holding pressure time during injection molding should be controlled between 5-15 seconds. A reasonable holding pressure time can prevent shrinkage marks on the product surface and improve the dimensional stability of the product. In the cup forming process, the holding time is set to 5-10 seconds to ensure that the sheet material can be fully cooled and shaped, effectively avoiding shrinkage caused by insufficient cooling.
[0030] Reference Figures 1-6 A thermoforming apparatus includes a lower mold 1 and an upper mold 2. The bottom of the lower mold 1 is equipped with a support frame for stable support of the entire apparatus. Two lifting push rods 16 are symmetrically installed on both sides of the upper mold 2, and fixing blocks 17 are fixed on both sides of the lower mold 1, with the fixing blocks 17 located directly below the lifting push rods 16. The output end of the lifting push rod 16 is connected to the corresponding fixing block 17, so that the up and down movement of the upper mold 2 can be controlled by the extension and retraction of the lifting push rod 16.
[0031] A C-shaped limit rod 18 is fixed to the side of the lower mold 1, and a first limit switch 19 and a second limit switch 20 are installed on the side of the upper mold 2. Both limit switches are located inside the C-shaped limit rod 18. Their function is to limit the movement of the upper mold 2 and ensure that the mold closing and opening actions are accurate.
[0032] The lower mold 1 has a first cavity 3 inside, in which a first mold sleeve 4 is placed. The upper edge of the first mold sleeve 4 has an inner rim for holding a plastic disc. Multiple first vent holes 5 are evenly distributed on the bottom side of the first mold sleeve 4, and a support member 6 is also provided inside. A first push rod 7 is installed below the lower mold 1, and the output end of the first push rod 7 is connected to the bottom of the support member 6. The extension and retraction of the first push rod 7 controls the up and down movement of the support member 6. In addition, a first airflow channel 42 is opened on the side of the lower mold 1, which communicates with the first cavity 3 and is at the same height as the first vent holes 5. This design facilitates gas flow.
[0033] The upper mold 2 has a second cavity 8 aligned with the first cavity 3, and a second mold sleeve 9 is installed inside the second cavity 8. Multiple second vent holes 10 are evenly distributed on the top side of the second mold sleeve 9, and a forming sleeve 11 is installed inside. The forming sleeve 11 is a forming cavity used for molding products, and the lower edge of the forming sleeve 11 is aligned with the inner edge of the first mold sleeve 4 to ensure accurate alignment during mold closing. Multiple third vent holes 12, aligned with the second vent holes 10, are also provided on the top side of the forming sleeve 11. A second airflow channel 13 is provided on the side of the upper mold 2, which is connected to the second cavity 8 and has the same height as the second vent holes 10, also for gas flow.
[0034] The molding sleeve 11 is equipped with an extrusion head 14. The upper end of the upper mold 2 is equipped with a second push rod 15. The output end of the second push rod 15 is connected to the upper end of the extrusion head 14. The extrusion head 14 can be moved up and down by extending and retracting the second push rod 15, thereby extruding and molding the material in the molding cavity.
[0035] It is important to note that after the PET disc is heated and softened, the softened PET disc is placed at the inner edge of the first mold sleeve 4. At this time, the edge of the PET disc is supported by the inner edge, while the middle part is supported by the support member 6 located inside the first mold sleeve 4, ensuring that the PET disc is in a stable state.
[0036] Next, the upper mold 2 is pressed down, so that the lower edge of the molding sleeve 11 is precisely pressed onto the outer periphery of the PET disc, completing the mold closing action. Subsequently, extruded gas is injected into the mold through the first airflow channel 42, while at the same time, the second airflow channel 13 on the side of the upper mold 2 begins to evacuate. Under the action of the gas, the middle part of the PET disc will gradually bulge upward, and with the upper push of the support 6, the PET disc will be tightly adhered to the inner wall of the molding sleeve 11, thereby achieving the effect of thermoforming and shaping the PET disc into the desired shape.
[0037] After the product inside the mold has cooled down, the upper mold 2 rises. Then, gas is injected into the second airflow channel 13, while the second push rod 15 drives the extrusion head 14 downward. Under the action of the extrusion head 14, the plastic cup is removed from the molding sleeve 11, thus completing the entire molding process.
[0038] This thermoforming process eliminates the need for stamping to remove excess material and recycling waste after the forming process is complete. This not only simplifies the process but also effectively reduces energy consumption.
[0039] Reference Figure 3 , Figure 5 and Figure 6 Cooling structures for cooling the mold and the molded product are respectively provided on the lower mold 1 and the upper mold 2.
[0040] In the lower mold 1, a first cooling groove 21 is formed on the outer side of the first mold sleeve 4. To ensure cooling effect and prevent leakage of cooling medium, three layers of sealing rings are provided on the outer side of the first mold sleeve 4. One layer is located above the first cooling groove 21, one layer is located between the first cooling groove 21 and the first vent hole 5, and the third layer is located below the first vent hole 5. At the same time, a first cooling medium flow channel 22 is provided through the side of the lower mold 1, and the first cooling medium flow channel 22 is aligned with the first cooling groove 21. In this way, the cooling medium can flow into the first cooling groove 21 through the first cooling medium flow channel 22 to cool the first mold sleeve 4.
[0041] In the upper mold 2 section, a second cooling groove 23 is provided on the outer side of the second mold sleeve 9. Similarly, to ensure cooling sealing, three layers of sealing rings are also provided on the outer side of the second mold sleeve 9: one layer below the second cooling groove 23, one layer between the second cooling groove 23 and the second vent hole 10, and another layer above the second vent hole 10. In addition, a through second cooling medium flow channel 24 is provided on the side of the upper mold 2. This second cooling medium flow channel 24 is aligned with the second cooling groove 23, and the cooling medium can enter the second cooling groove 23 through the second cooling medium flow channel 24 to achieve cooling of the second mold sleeve 9.
[0042] The implementation principle of this embodiment is as follows: After the PET disc is heated and softened, it is placed inside the inner edge of the first mold sleeve 4, with the edges and middle supported by the inner edge and the support member 6, respectively. The upper mold 2 presses down, air is injected through the first airflow channel 42, air is extracted through the second airflow channel 13, and the support member 6 pushes up, causing the disc protrusion to conform to the inner wall of the molding sleeve 11 to complete thermoforming. After cooling, the extrusion head 14 pushes out the plastic cup. There is no need for stamping, cutting, or waste recycling, making the process simple and energy-efficient.
[0043] Example 2: Reference Figures 7-10The difference between this embodiment and Embodiment 1 is that: a mounting plate 25 is fixed to the side of the lower mold 1, and a clamping element 35 is mounted on the upper side of the mounting plate 25. A base plate 26 is slidably mounted on the clamping element 35, the bottom of the base plate 26 is flush with the upper surface of the lower mold 1, and a discharge port 28 is opened on it. An edge housing 27 is fixed to the upper surface of the base plate 26, and two limiting screws 33 are symmetrically fixed to the upper end of the base plate 26.
[0044] Two symmetrical limiting protrusions 34 are provided on the outer side of the edge housing 27, and two symmetrical limiting protrusions 29 are fixed on the inner side. A pull-out plate 30 is slidably arranged between the limiting protrusions 29 and the base plate 26. Above the pull-out plate 30 is an inclined surface 31 made of metal, in which an electric heating plate 36 is embedded, and the upper surface is coated with polytetrafluoroethylene. A weight-reducing groove 37 is formed on the upper surface of the pull-out plate 30, and several heat dissipation fins 38 are arranged in the groove.
[0045] An inclined plate 32 is provided above the edge housing 27, with its lower edge abutting against the upper surface of the inclined slope 31. A rotating shaft 39 is rotatably mounted on the lower surface of the inclined plate 32, with both ends of the shaft 39 rotatably connected to the edge housing 27, and each end is fitted with a torsion spring 41. A stop block 40 is fixed inside the edge housing 27, with one end of the torsion spring 41 abutting against the stop block 40 and the other end abutting against the lower surface of the inclined plate 32.
[0046] It is important to note that, firstly, the base plate 26 is pulled outwards. At this time, the limiting screw 33 will block the side wall of the clamping piece 35, acting as a limit and completely separating it from the lower mold 1. Then, the softened PET disc is placed on the inclined plate 32. The PET disc slides down the inclined plate 32 onto the inclined slope 31. Then, the base plate 26 is pushed into the middle of the lower mold 1. When the limiting protrusion 34 abuts against the clamping piece 35, the inclined slope 31 is located directly above the first mold sleeve 4. Then, keeping the base plate 26 stationary, the pull plate 30 is pulled outwards. Through the elastic force of the torsion spring 41, the inclined plate... The lower end of plate 32 presses against the inclined plate 31 and remains in a resisting state as the inclined plate 31 is pulled outward. Under the obstruction of the inclined plate 32, the PET disc will not move outward. As the inclined plate 31 is pulled back, the PET disc is gradually placed onto the first mold sleeve 4. When the inclined plate 31 is completely pulled out, the PET disc is successfully placed on the inner edge of the first mold sleeve 4. Then the bottom plate 26 is pulled outward, completely separating from the lower mold 1 without affecting the mold closing. The entire placement process is smoother, the PET disc is placed more accurately, and there will be no skewing, ensuring product quality.
[0047] Furthermore, the electric heating plate 36 can heat the inclined slope 31 to prevent the PET disc from cooling down too early when it is placed in place. At the same time, the polytetrafluoroethylene coating can reduce the friction between the inclined slope 31 and the PET disc, making it easier to unload the PET disc. Meanwhile, the heat dissipation fins 38 can improve the heat dissipation effect and prevent the other end of the pull plate 30 from being burned by high temperature.
[0048] The implementation principle of this embodiment is as follows: First, pull the base plate 26 outward to detach it from the lower mold 1. Place the softened PET disc onto the inclined plate 32, and the disc slides to the inclined slope 31. Then, push the base plate 26 towards the center of the mold, so that the inclined slope 31 is directly above the first mold sleeve 4. Next, pull out the pull plate 30. The disc does not move backward due to the obstruction of the inclined plate 32, and falls back down with the slope to the inner edge of the first mold sleeve 4. Finally, pull out the base plate 26. This process is smooth, the disc is placed accurately, and product quality can be guaranteed.
[0049] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.
Claims
1. A thermoforming process, characterized in that: include: Raw material drying: Dehumidify and dry the PET raw materials; Injection molding: PET raw materials are injection molded into a circular sheet structure using an injection molding machine and then cooled; Cup body forming: The circular sheet-shaped PET semi-finished product is heated, formed by molding through a mold, and then cooled and shaped.
2. The injection molding process according to claim 1, characterized in that: In the raw material drying step, the proportion of recycled material should not exceed 25%. A dehumidifying dryer is used, with a drying temperature of 150-170℃ and a drying time of 3-4 hours. The moisture content after drying should be controlled to be below 0.005%. If the moisture content exceeds the standard, the drying time should be extended. In the injection molding step, the barrel temperature is controlled at 240-260℃ in the feeding zone, 260-280℃ in the melting zone, and 270-280℃ in the nozzle zone. A melt thermocouple is used for real-time monitoring, and the temperature fluctuation should be ≤±3℃. The injection pressure is 80-120MPa, the holding pressure is 50%-70% of the injection pressure, and the holding time is 5-15 seconds. In the cup body molding step, the heating temperature of the round sheet-shaped PET semi-finished product is 100-120℃, the mold temperature is 10-30℃, the holding time is 5-10 seconds, the cooling water temperature is 10-15℃, and the cooling time is 5-10 seconds.
3. A thermoforming apparatus, characterized in that, The injection molding process described in claim 1 or 2 includes a lower mold (1) and an upper mold (2). The lower mold (1) is provided with a first cavity (3). A first mold sleeve (4) is provided in the first cavity (3). An inner rim for placing a plastic disc is provided on the inner side of the upper edge of the first mold sleeve (4). Several circumferentially distributed first ventilation holes (5) are opened at the bottom of the side end of the first mold sleeve (4). A support member (6) is provided inside the first mold sleeve (4). A first push rod (7) is installed below the lower mold (1). The output end of the first push rod (7) is fixed to the bottom of the support member (6) to control the up and down movement of the support member (6). A first airflow channel (42) is opened on the side of the lower mold (1). The first airflow channel (42) is connected to the first cavity (3). The first airflow channel (42) is at the same height as the first ventilation hole (5). A second cavity aligned with the first cavity (3) is opened on the upper mold (2). 8) The second cavity (8) is provided with a second mold sleeve (9). The top of the side end of the second mold sleeve (9) is provided with several circumferentially distributed second ventilation holes (10). The second mold sleeve (9) is provided with a forming sleeve (11). The forming sleeve (11) is provided with a forming cavity. The lower edge of the side of the forming sleeve (11) is aligned with the inner edge of the first mold sleeve (4). The top of the side end of the forming sleeve (11) is provided with several third ventilation holes (12) aligned with the second ventilation holes (10). The side of the upper mold (2) is provided with a second airflow channel (13). The second airflow channel (13) is connected to the second cavity (8). The second airflow channel (13) is at the same height as the second ventilation hole (10). The forming sleeve (11) is provided with an extrusion head (14). The upper end of the upper mold (2) is equipped with a second push rod (15). The output end of the second push rod (15) is fixed to the upper end of the extrusion head (14) to control the up and down movement of the extrusion head (14).
4. The thermoforming apparatus according to claim 3, characterized in that: The upper mold (2) has two symmetrically distributed lifting push rods (16) fixed on its side end. The lower mold (1) has fixed blocks (17) fixed on both sides. The fixed blocks (17) are located directly below the lifting push rods (16), and the output end of the lifting push rods (16) is fixedly connected to the fixed blocks (17) at the corresponding positions. The lower mold (1) has a C-shaped limit rod (18) fixed on its side end. The upper mold (2) has a first limit switch (19) and a second limit switch (20) fixed on its side end. The first limit switch (19) and the second limit switch (20) are both located inside the C-shaped limit rod (18).
5. A thermoforming apparatus according to claim 3, characterized in that: The outer side of the first mold sleeve (4) is provided with a first cooling groove (21), and the outer side of the first mold sleeve (4) is provided with three layers of sealing rings located above the first cooling groove (21), between the first cooling groove (21) and the first vent (5), and below the first vent (5). The side of the lower mold (1) is provided with a through first cooling medium channel (22), and the first cooling medium channel (22) is aligned with the first cooling groove (21). The outer side of the second mold sleeve (9) is provided with a second cooling groove (23), and the outer side of the second mold sleeve (9) is provided with three layers of sealing rings located below the second cooling groove (23), between the second cooling groove (23) and the second vent (10), and above the second vent (10). The side of the upper mold (2) is provided with a through second cooling medium channel (24), and the second cooling medium channel (24) is aligned with the second cooling groove (23).
6. The thermoforming apparatus according to claim 3, characterized in that: The lower mold (1) is fixed with a mounting plate (25) on its side. A clip (35) is fixed on the upper side of the mounting plate (25). A base plate (26) is slidably mounted on the clip (35). A discharge port (28) is opened on the base plate (26). The bottom of the base plate (26) is flush with the upper surface of the lower mold (1). An edge shell (27) is fixed on the upper surface of the base plate (26). Two symmetrically distributed limiting protrusions (29) are fixed on the inner side of the edge shell (27). A pull plate (30) is slidably mounted between the limiting protrusions (29) and the base plate (26). An inclined slope (31) is provided above the pull plate (30). An inclined plate (32) is provided above the edge shell (27). The inclined plate (32) and the lower edge abut against the upper surface of the inclined slope (31).
7. A thermoforming apparatus according to claim 6, characterized in that: The upper end of the base plate (26) is fixed with two symmetrically distributed limiting screws (33), and the outer side of the edge shell (27) is fixed with two symmetrically distributed limiting protrusions (34).
8. A thermoforming apparatus according to claim 6, characterized in that: An electric heating plate (36) is embedded below the inclined surface (31), and the inclined surface (31) is made of metal. The upper surface of the inclined surface (31) is coated with polytetrafluoroethylene. A weight-reducing groove (37) is opened on the upper surface of the pull plate (30), and several heat dissipation fins (38) are provided in the weight-reducing groove (37).
9. A thermoforming apparatus according to claim 6, characterized in that: The lower surface of the inclined plate (32) is rotatably provided with a rotating shaft (39), and both ends of the rotating shaft (39) are rotatably connected to the edge housing (27). Both ends of the rotating shaft (39) are fitted with torsion springs (41). A stop block (40) is fixed on the inner side of the edge housing (27). One end of the torsion spring (41) abuts against the stop block (40), and the other end abuts against the lower surface of the inclined plate (32).