A plastic bottle manufacturing process and molding die

Abstract

This invention discloses a plastic bottle manufacturing process and molding die, comprising the following steps: S1, inserting the upper die into the first cavity of the first lower die from top to bottom and closing the upper die with the first lower die; S2, operating the first extruder to perform injection molding on the first lower die; S3, operating the second extruder to perform re-injection molding on the lower part of the first preform; S4, closing the upper die with the second lower die; S5, heating the second mold cavity; S6, lowering the die core of the upper die and introducing low-pressure gas into the air inlet channel; S7, lowering the die core to elongate the second preform and introducing high-pressure gas into the air inlet channel for blow molding; S8, after blow molding is completed, the die core rises and resets, forming a thick-bottomed plastic bottle. This invention, through the coordinated operation of the upper die, the first lower die, the second lower die, the first extruder, and the second extruder, enables the blow molding of thick-bottomed, high-transparency plastic bottles, resulting in a finished plastic bottle with an appearance similar to a glass bottle, effectively reducing production costs.

Description

Technical Field

[0001] This invention relates to containers, and more specifically, to a plastic bottle manufacturing process and molding die. Background Technology

[0002] Bottles are generally used to hold liquids or lotions and are widely used in the cosmetics industry. Currently, some high-end lotion bottles adopt a thick-bottom, high-transparency design to enhance the overall quality. To achieve the thick-bottom effect, the thickness of the bottom of the bottle is much greater than the thickness of the rest of the wall (generally, the thickness of the bottom is 4-5 times the thickness of the bottle wall). Because the overall thickness of the bottle is very different, this type of bottle cannot be made by blow molding of high-transparency plastics and can only be made by blow molding of glass. This results in very high production costs for this type of bottle and it is also easy to be damaged. Therefore, there is an urgent need to improve this. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a plastic bottle production process and molding die. Through the coordinated operation of the upper die, the first lower die, the second lower die, the first extruder and the second extruder, the blow molding of thick-bottomed, high-transparency plastic bottles can be achieved, making the appearance of the molded plastic bottle similar to that of a glass bottle, thus effectively reducing production costs.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: a plastic bottle manufacturing process, comprising the following steps:

[0005] S1. Insert the upper mold into the first cavity of the first lower mold from top to bottom and close the mold with the first lower mold;

[0006] S2. The first extruder operates, injecting and molding the first lower die, and after cooling, the first preform is formed;

[0007] S3. The second extruder operates to re-inject the lower part of the first preform, and after cooling, it forms a second preform with a thickened bottom.

[0008] S4. Close the upper mold and the second lower mold together, and the main body of the second blank is located in the second mold cavity;

[0009] S5. Heat the second mold cavity to soften the second preform;

[0010] S6. The mold core of the upper mold descends, and the air intake channel inside the mold core is connected to the inner wall of the second preform, and low-pressure gas is introduced into the air intake channel.

[0011] S7. The mold core descends and elongates the second preform until the lower part of the second preform abuts the bottom of the second mold cavity, and high-pressure gas is introduced into the air inlet channel for blow molding;

[0012] S8. After blow molding is completed, the mold core rises and resets, forming a thick-bottomed plastic bottle.

[0013] Furthermore, in step S3, the second extruder is located in the first lower die, and the second preform is formed within the first lower die.

[0014] Furthermore, step S3 also includes the following steps:

[0015] ① The slider inside the first lower mold descends, and a first molding cavity is formed between the upper part of the slider and the lower part of the first blank;

[0016] ② The area of ​​the first mold cavity located in the first molding cavity is heated and softened to soften the portion of the first preform located in the first molding cavity;

[0017] ③ The second extruder operates to inject plastic into the first molding cavity, and the molten plastic particles fill the first molding cavity and combine with the first preform.

[0018] ④ After cooling, a second embryo is formed.

[0019] Furthermore, in step S3, the second extruder is located in the lower die holder, which is located at the lower part of the second lower die, and the second preform is formed in the lower die holder.

[0020] Furthermore, step S3 also includes the following steps:

[0021] ① Insert the upper mold carrying the first blank into the third mold cavity of the lower mold base from top to bottom, and the first blank and the bottom of the third mold cavity form a second molding cavity;

[0022] ② The two third templates are closed, and the third templates abut against the periphery of the first blank;

[0023] ③ The third mold cavity heats and softens the portion of the first preform located in the second molding cavity;

[0024] ④ The second extruder operates to inject plastic into the second molding cavity, and the molten plastic particles fill the second molding cavity and combine with the first preform.

[0025] ⑤ After cooling, a second embryo is formed.

[0026] Furthermore, step S4 also includes the following steps:

[0027] ① The upper mold carrying the second preform is raised and detached from the third mold cavity;

[0028] ② The two second templates of the second lower mold are closed, and the main body of the second blank is located in the second mold cavity.

[0029] Furthermore, the plastic bottle body is made of PET high-transparency plastic particles.

[0030] A plastic bottle forming mold, wherein the upper mold includes a first module, a mold core, an ejector pin, and a first template;

[0031] The mold core penetrates the first module. The mold core includes an air inlet channel and an air outlet. The air outlet is connected to the lower end of the air inlet channel. The push rod is located in the air inlet channel and can be inserted into or removed from the air outlet. There are two first templates located around the mold core. When the two first templates are closed, they form a bottle mouth forming area of ​​the plastic bottle body between the mold core and the outer wall of the mold core.

[0032] The first lower mold includes a first mold cavity. When forming the first blank, the lower part of the first template abuts against the upper part of the first lower mold and the mold core is inserted into the first mold cavity.

[0033] The second lower mold includes two first templates. The two first templates are joined together to form a second mold cavity. When molding the plastic bottle, the lower part of the first template abuts against the upper part of the second lower mold and the mold core is inserted into the second mold cavity.

[0034] Furthermore, the first lower mold also includes a first feeding channel, a guide groove, and a second feeding channel. The first feeding channel and the second feeding channel are located on both sides of the first lower mold, and the first feeding channel is connected to the side wall of the first mold cavity.

[0035] A slider is slidably connected in the guide groove. The slider includes a boss and a fourth feeding channel. The lower part of the first mold cavity is an opening. The upper part of the boss is embedded in the opening of the lower part of the first mold cavity and blocks the opening. One end of the fourth feeding channel is connected to the bottom of the first mold cavity and the other end is connected to the outer wall of the slider.

[0036] When forming the first blank, the upper part of the slider abuts against the top of the guide groove, and the fourth feeding channel is blocked from the second feeding channel;

[0037] When forming the second preform, the upper part of the slider separates from the top of the guide groove, and a first forming cavity is formed between the upper part of the slider and the lower part of the first preform. The fourth feeding channel is connected to the second feeding channel.

[0038] Furthermore, it also includes a lower mold base, which includes a third template, a base, a third mold cavity, and a third feeding channel;

[0039] The third mold cavity and the third feeding channel are both located inside the base. One end of the third feeding channel is connected to the bottom of the third mold cavity and the other end is connected to the outer wall of the base. The third template is located on the upper part of the base. There are two third templates that can be close to or far from each other.

[0040] When forming the second preform, the lower end of the upper mold carrying the first preform is inserted into the third mold cavity, and a second forming cavity is formed between the lower part of the first preform and the third mold cavity. The two third mold templates close together and clamp the first preform.

[0041] In summary, the present invention has the following beneficial effects:

[0042] 1. By raising and lowering the slider, the effective molding depth of the first mold cavity can be flexibly changed. Relying on the adjustable mold cavity depth, secondary injection molding can be achieved within the same first lower mold, improving efficiency and reducing costs. First, a first preform with uniform wall thickness is injection molded at the initial cavity depth, ensuring consistent wall thickness and stable molding quality of the basic preform. After completing the injection molding of the first preform with uniform wall thickness, the slider is moved downward to continue injection molding on the basis of the first preform to form a second preform, so that a thickened part is formed at the bottom of the second preform. After the thickened part is combined with the wall thickness of the first preform, its thickness reaches 4-5 times the conventional wall thickness of the first preform. Using this injection molding method, the defects of injection molding such as internal bubbles, surface shrinkage marks, material overheating and scorching, and uneven filling that are prone to occur in thick-walled areas due to excessive local wall thickness differences are avoided, thereby solving the technical problem that traditional processes cannot achieve thick-bottomed plastic bottles.

[0043] 2. Airflow is introduced into the second preform through the air intake channel inside the mold core. Using a pneumatic expansion blow molding process, the preform is made to conform entirely to the inner wall of the second mold cavity for shaping. Simultaneously, under the combined action of blow molding tension and the mold cavity shape, the bottom of the bottle naturally forms a shape resembling... Figure 1 The concave, thick-bottomed area shown in Figure 'a' creates a thick-bottomed plastic bottle, which, from its appearance, exhibits a noticeable height effect due to its thick bottom. Because the plastic particles used are high-transparency PET particles, a high-transparency, thick-bottomed plastic bottle can be made. The resulting plastic bottle has a strong three-dimensional effect due to its thick bottom, and its overall visual texture is very close to that of a high-transparency, thick-bottomed glass bottle. However, the production cost is much lower than that of a glass bottle. PET material has good toughness and strong impact resistance, and the thick bottom structure further enhances the bottom support strength, making it less prone to breakage and deformation. Unlike glass bottles, which are fragile, it is more durable and environmentally friendly. Attached Figure Description

[0044] Figure 1 This is a flowchart of the plastic bottle molding process.

[0045] Figure 2 This is a schematic diagram of the first preform forming process in Example 1;

[0046] Figure 3 This is a schematic diagram of the second embryo forming process in Example 1;

[0047] Figure 4 This is a schematic diagram of the plastic bottle body before molding in Example 1;

[0048] Figure 5 This is a schematic diagram of the plastic bottle molding process in Example 1;

[0049] Figure 6 This is a schematic diagram of the first preform forming process in Example 2;

[0050] Figure 7 This is a schematic diagram of the second embryo forming process in Example 2;

[0051] Figure 8 This is a schematic diagram of the plastic bottle body before molding in Example 2;

[0052] Figure 9 This is a schematic diagram of the plastic bottle molding process in Example 2;

[0053] Figure 10 This is a schematic diagram of a plastic bottle.

[0054] Reference numerals: 1. Upper mold; 11. First module; 12. Mold core; 121. Air inlet channel; 122. Air outlet; 13. Ejector pin; 14. First template; 2. First lower mold; 21. First mold cavity; 211. First forming cavity; 22. First feeding channel; 23. Guide groove; 24. Second feeding channel; 3. Second lower mold; 31. Second template; 32. Second mold cavity; 4. Lower mold base; 41. Third template; 42. Base; 43. Third mold cavity; 431. Second forming cavity; 44. Third feeding channel; 5. Slider; 51. Boss; 52. Fourth feeding channel; 6. First extruder; 7. Second extruder; 100. First preform; 200. Second preform; 300. Thickened part; 400. Plastic bottle body. Detailed Implementation

[0055] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] Example 1:

[0057] like Figures 1 to 5 As shown, this embodiment discloses a plastic bottle manufacturing process, which includes the molding of a first preform 100, the molding of a second preform 200, and the blow molding of the final plastic bottle body 400. The first preform 100 and the second preform 200 are injection molded by the mold-fitting and cooperating operation of the upper mold 1 and the first lower mold 2. The molded second preform 200 is then transferred to the molding station, where the upper mold 1 and the second lower mold 3 are matched and molded together. After being stretched, expanded, cooled and shaped by the blow molding process, the complete plastic bottle body 400 is finally produced.

[0058] like Figure 2As shown, the upper mold 1 includes a first module 11, a mold core 12, an ejector pin 13, and a first template 14;

[0059] The first module 11 is fixedly installed and connected to the transfer device inside the molding equipment. Relying on the power transmission and displacement control function of the transfer device, it can reliably drive the upper mold 1 to complete the composite motion of horizontal translation and vertical lifting, thereby realizing the transfer action of the upper mold between different work stations. The transfer device adopts a mature existing technology structure, which is not shown in the figure. For example, a conventional linear displacement drive mechanism such as an XYZ three-axis drive device can be selected to meet the usage requirements.

[0060] The mold core 12 vertically penetrates the first module 11 and can slide smoothly up and down within the first module 11. The top of the mold core 12 extends upward and is connected to an external servo drive motor. The technology of the servo drive motor driving the mold core 12 to rise and fall is existing technology. Therefore, its specific connection structure and lifting principle will not be described in detail in this specification. During operation, the servo drive motor provides precise power output to drive the mold core 12 to make a smooth reciprocating motion of rising and falling. When it goes down, it axially stretches the second preform 200 so that the second preform reaches the preset stretching ratio and shape, creating good conditions for the subsequent high-pressure inflation and expansion shaping inside the cavity, effectively ensuring the accuracy and overall molding quality of the blow molding of the plastic bottle 400.

[0061] like Figure 5 As shown, the mold core 12 includes an air inlet channel 121 and an air outlet 122. The air outlet 122 is connected to the lower end of the air inlet channel 121. The upper end of the air inlet channel 121, away from the air outlet 122, is connected to an external air supply pipeline. The sealing connection, pipeline layout, and connection fixing method between the air inlet channel 121 and the external air supply pipeline all adopt existing mature technologies, so this specification will not elaborate further. During operation, the external air supply pipeline supplies gas to the air inlet channel 121. The gas flows downward along the air inlet channel 121 and is evenly blown out through the air outlet 122, entering the interior of the second preform 200. The expansion force of the gas expands the second preform 200 and tightly adheres it to the inner wall of the mold cavity, thereby completing the overall blow molding and shaping of the plastic bottle 400. The gas supply principle used in this solution adopts existing mature technologies, so this specification will not elaborate further.

[0062] like Figure 4 and Figure 5As shown, the ejector rod 13 is coaxially inserted inside the air inlet channel 121 of the mold core 12. The ejector rod 13 is always fixed and stationary and does not slide axially. The upper end of the ejector rod 13 passes through the mold core 12 and forms a precision sealed sliding fit with the mold core 12. One end of the ejector rod 13 that passes through the mold core 12 is fixedly connected to the transfer device inside the molding equipment. When the mold core 12 moves downward, it will not drive the ejector rod 13 to move. Only the servo mechanism drives the mold core 12 to make up-down axial sliding motion. Through the lifting displacement of the mold core 12 itself, the stretching and shaping of the second preform 200 and the opening and closing of the air inlet channel 121 and the air outlet 122 are completed.

[0063] like Figure 2 As shown, there are two first templates 14, which are symmetrically arranged on the outer periphery of the mold core 12. Each first template 14 is fixedly equipped with a driving cylinder on its outer side. The two sets of first templates 14 are driven by the extension and retraction of the cylinder to realize the action of closing towards each other and separating away from each other. After the two sets of first templates 14 are closed, their inner surfaces cooperate with the outer wall of the mold core 12 to jointly enclose and form the bottle mouth forming cavity of the plastic bottle body 400.

[0064] like Figure 2 and Figure 3 As shown, the first lower mold 2 includes a first mold cavity 21, a first feeding channel 22, a guide groove 23, and a second feeding channel 24;

[0065] The first lower mold 2 is securely installed and fixed on the worktable of the molding equipment. A heating wire assembly is pre-embedded inside the first lower mold 2. The heating wire is energized to generate heat and maintain a constant temperature for the first mold cavity 21, so as to meet the temperature conditions required for the injection molding of the preform. The heating wire is a conventional existing structure in the industry, so its specific arrangement and installation structure will not be described in detail in this application.

[0066] The first mold cavity 21 is vertically connected inside the first lower mold 2. Both the upper and lower ends of the first mold cavity 21 are open. The guide groove 23 is located inside the first lower mold 2. The upper end of the guide groove 23 is connected to the lower port of the first mold cavity 21. The cross-sectional dimension of the guide groove 23 is larger than that of the first mold cavity 21, providing sufficient sliding installation space and motion guidance limit for the slider 5.

[0067] A slider 5 is slidably connected inside the guide groove 23. The lower end of the slider 5 is connected to an external servo motor (not shown in the figure). The servo motor can accurately output power to drive the slider 5 to make a smooth up-and-down linear reciprocating motion inside the guide groove 23. The slider 5 is integrally provided with a boss 51 and a fourth feeding channel 52. The upper end of the boss 51 is adapted to be embedded in the opening at the lower part of the first mold cavity 21 and blocks the opening to achieve sealing. During the entire process of the slider 5 sliding up and down, the boss 51 always maintains the state of blocking the lower port of the first mold cavity 21 to avoid material leakage and ensure the cavity airtightness and injection feeding stability.

[0068] By raising and lowering the slider 5, the effective molding depth of the first mold cavity 21 can be flexibly changed. Relying on the adjustable change of the mold cavity depth, secondary injection molding can be achieved within the same first lower mold 2, improving efficiency and reducing costs. First, a first preform 100 with uniform wall thickness is injection molded at the initial cavity depth to ensure consistent wall thickness and stable molding quality of the basic preform. After the injection molding of the first preform 100 with uniform wall thickness is completed, the slider 5 is moved downward to continue injection molding on the basis of the first preform 100 to form a second preform 200, so that a thickened part 300 is formed at the bottom of the second preform 200. After the thickened part 300 is combined with the wall thickness of the first preform 100, its thickness reaches 4-5 times the conventional wall thickness of the first preform 100. Using this injection molding method, the defects of injection molding such as internal bubbles, surface shrinkage marks, material scorching due to excessive local wall thickness differences and uneven filling that are prone to occur in thick-walled areas are avoided, thereby solving the technical problem that traditional processes cannot achieve thick-bottomed plastic bottles 400.

[0069] like Figure 2 As shown, the first feeding channel 22 and the second feeding channel 24 are located on both sides of the first lower mold 2. The first feeding channel 22 is connected to the side wall of the first mold cavity 21. One end of the fourth feeding channel 52 is connected to the bottom of the first mold cavity 21 and the other end is connected to the outer wall of the slider 5.

[0070] like Figure 2 As shown, in the process of forming the first preform 100, the two sets of first mold plates 14 close downwards and press against the upper surface of the first lower mold 2. The mold core 12 moves downwards synchronously and is precisely inserted into the first mold cavity 21 for mold closing and positioning. At this time, the servo motor drives the slider 5 to move upwards to the top limit position of the guide groove. The upper part of the slider 5 abuts against the top of the guide groove 23, so that the fourth feeding channel 52 and the second feeding channel 24 are separated. At the same time, the first extruder 6 delivers molten plastic raw material into the first mold cavity 21 through the first feeding channel 22. Since the fourth feeding channel 52 and the second feeding channel 24 are blocked, the molten material cannot leak out and can only completely fill the first mold cavity 21, thereby completing the forming of the first preform 100.

[0071] like Figure 3As shown, when the second preform 200 is formed, the slider 5 descends, and its upper part disengages from the top of the guide groove 23. A first forming cavity 211 is formed between the upper part of the slider 5 and the lower part of the first preform 100. After the slider 5 moves into place, the fourth feeding channel 52 and the second feeding channel 24 are automatically connected and the flow passage is opened. The extrusion head of the second extruder 7 is connected to the second feeding channel 24, and material is injected into the first forming cavity 211 through the second extruder 7. Since the first feeding channel 22 is blocked by the first preform 100, the first preform 100 is formed in the first preform 200. If there is no blockage, the material cannot flow out from the first feed channel 22. At this time, the second extruder 7 injects molten plastic into the first molding cavity 211 above the slider 5 through the second feed channel 24 and the fourth feed channel 52. The first feed channel 22 has been completely blocked by the solidified first preform 100, so the molten material will not leak and will only fill and accumulate in the first molding cavity 211. Therefore, a thickened part 300 can be formed at the bottom of the first preform 100, thus realizing the molding of the second preform 200 with a thickened bottom.

[0072] like Figure 3 , Figure 4 and Figure 10 As shown, the second lower mold 3 includes two second templates 31. The two second templates 31 are closed to form a second mold cavity 32. When molding the plastic bottle body 400, the lower part of the first template 14 abuts against the upper part of the second lower mold 3 and the mold core 12 is inserted into the second mold cavity 32, completing the overall mold closing and locking.

[0073] Airflow is introduced into the second preform 200 through the air inlet channel 121 inside the mold core 12. Using a pneumatic expansion blow molding process, the preform is molded to conform to the inner wall of the second mold cavity 32. Simultaneously, under the combined action of blow molding tension and mold cavity shaping, the bottom of the bottle naturally forms a shape resembling... Figure 1 The concave, thick-bottomed area shown in Figure a creates a thick-bottomed plastic bottle 400, which, from an external perspective, exhibits a noticeable height effect due to its thick bottom. Because the plastic particles used are high-transparency PET particles, a high-transparency, thick-bottomed plastic bottle 400 can be produced. The resulting plastic bottle 400 has a strong three-dimensional effect due to its thick bottom, and its overall visual texture closely resembles that of a high-transparency, thick-bottomed glass bottle. However, its production cost is far lower than that of a glass bottle. PET material has good toughness and impact resistance, and the thick-bottomed structure further enhances the bottom support strength, making it less prone to breakage and deformation. Unlike glass bottles, which are fragile, it is more durable and environmentally friendly.

[0074] The manufacturing process using the molding die in this embodiment includes the following steps:

[0075] S1, such as Figure 2 As shown, the transfer device of the molding equipment drives the upper mold 1 to move vertically downwards, and the upper mold 1 is inserted into the first cavity 21 of the first lower mold 2 from top to bottom and closes with the first lower mold 2.

[0076] S2, such as Figure 2 As shown, the first extruder 6 operates to inject the first lower die 2 into the mold, and after cooling, it forms the first preform 100.

[0077] Specifically, the first extruder 6 drives the extrusion head to move, so that the extrusion head is connected to the first feed channel 22 and molten PET material is extruded. The temperature control of the extrusion head is set in sections: 240°C for the rear section, 255°C for the middle section, and 265°C for the front section. The material is injected into the first cavity 21 of the first mold 2 through the gating channel at a uniform speed with an injection pressure of 90MPa~110MPa and an injection speed of 60mm / s~80mm / s.

[0078] A holding pressure of 50MPa to 60MPa and a holding time of 3s to 5s are used to ensure that the melt completely fills the cavity;

[0079] After the pressure holding is completed, the cooling and shaping stage begins. The cooling time is set to 12s to 18s. The molten plastic in the cavity is cooled gradually and evenly by relying on the circulating cooling water inside the mold to dissipate heat at a constant temperature.

[0080] S3, such as Figure 3 As shown, the second extruder 7 operates to re-inject the lower part of the first preform 100, and after cooling, it forms a second preform 200 with a thickened part 300 at the bottom.

[0081] Specifically, the second extruder 7 is located in the first lower die 2, and the second preform 200 is formed in the first lower die 2;

[0082] ① The servo motor drives the slider 5 inside the first lower mold 2 to descend, and the upper part of the slider 5 and the lower part of the first blank 100 form the first molding cavity 211, with a descending stroke of 6-8mm;

[0083] ② The area of ​​the first mold cavity 21 located in the first molding cavity 211 is heated and softened to soften the portion of the first preform 100 located in the first molding cavity 211;

[0084] The heating component built into the first lower mold 2 heats the area of ​​the first mold cavity 21 corresponding to the first molding cavity 211 at a constant temperature, softening the bottom joint of the first preform 100 and making the surface of the preform reach a molten and compatible state, creating conditions for the hot-melt bonding of the new and old melts. The local heating temperature is 95-105℃, which only softens without damaging the original structure and shape of the first preform 100.

[0085] ③ The second extruder 7 operates to inject plastic into the first molding cavity 211, and the molten plastic particles fill the first molding cavity 211 and combine with the first preform 100.

[0086] Extrusion head segment temperatures: rear section 235℃, middle section 250℃, front section 260℃;

[0087] With an injection pressure of 85-105MPa and an injection speed of 55-75mm / s, molten plastic is injected into the first molding cavity 211 through a dedicated flow channel. The molten material quickly fills the entire cavity and fully melts and fuses with the bottom of the heated and softened first preform 100, forming an integral structure.

[0088] A pressure of 45–55 MPa and a holding time of 12–15 seconds are used to compensate for shrinkage and prevent shrinkage marks and delamination at the joint.

[0089] ④ After cooling, a second preform 200 is produced;

[0090] After the injection molding pressure is maintained, the mold cooling water circulation is started to keep the first molding cavity 211 at a constant temperature for cooling and shaping for 10-16 seconds.

[0091] S4, such as Figure 4 As shown, the upper mold 1 and the second lower mold 3 are closed together, and the main body of the second blank 200 is located in the second mold cavity 32;

[0092] S5. Heat the second mold cavity 32 to soften the second preform 200;

[0093] The second lower mold 3 has a built-in temperature control heating system that is activated to perform constant temperature heating on the second mold cavity 32, and to uniformly heat and keep the entire second preform 200 warm, so that the material of the second preform 200 reaches a highly elastic and softened state, and has good tensile and ductile properties.

[0094] S6, such as Figure 5 As shown, the mold core 12 of the upper mold 1 slowly descends, and the air intake channel 121 inside the mold core 12 is connected to the inner wall of the second preform 200, and low-pressure gas is introduced into the air intake channel 121.

[0095] Initially, low-pressure compressed gas is introduced to pre-inflate and support the interior of the second preform 200, so that the softened second preform 200 is initially stretched and fits the local surface of the cavity, preventing the second preform 200 from collapsing, wrinkling and deforming during the stretching process.

[0096] S7. The mold core 12 descends and elongates the second preform 200 until the lower part of the second preform 200 abuts the bottom of the second mold cavity 32, and high-pressure gas is introduced into the air inlet channel 121 for blow molding.

[0097] When the bottom of the second preform 200 reaches the bottom limit position of the second mold cavity 32, the axial stretching stops, and the system immediately switches the air supply mode, changing from low pressure to high pressure gas to be continuously blown in.

[0098] Under the action of high-pressure airflow, the softened second preform 200 expands outward evenly and fits tightly with the inner wall contour of the second mold cavity 32. It is shaped according to the mold cavity shape and simultaneously forms a concave thickened structure at the bottom of the bottle.

[0099] S8, such as Figure 10 As shown, after blow molding is completed, the mold core 12 rises and resets, forming a thick-bottomed plastic bottle body 400.

[0100] Example 2:

[0101] like Figure 1 , Figures 6 to 10 As shown, this embodiment discloses a plastic bottle manufacturing process, which includes the molding of a first preform 100, the molding of a second preform 200, and the blow molding of the final plastic bottle body 400. The first preform 100 is pre-molded by injection molding through the mold-fitting and cooperating operation of the upper mold 1 and the first lower mold 2. The molded first preform 100 is then transferred to the molding station, where the upper mold 1 and the lower mold base 4 match and fit together to form the second preform 200. Then, the second preform 200 is matched and fitted together with the second lower mold 3. After being stretched, expanded, cooled and shaped by the blow molding process, the complete plastic bottle body 400 is finally formed.

[0102] like Figure 6 As shown, the upper mold 1 includes a first module 11, a mold core 12, an ejector pin 13, and a first template 14;

[0103] The first module 11 is fixedly installed and connected to the transfer device inside the molding equipment. Relying on the power transmission and displacement control function of the transfer device, it can reliably drive the upper mold 1 to complete the composite motion of horizontal translation and vertical lifting, thereby realizing the transfer action of the upper mold between different work stations. The transfer device adopts a mature existing technology structure, which is not shown in the figure. For example, a conventional linear displacement drive mechanism such as an XYZ three-axis drive device can be selected to meet the usage requirements.

[0104] The mold core 12 vertically penetrates the first module 11 and can slide smoothly up and down within the first module 11. The top of the mold core 12 extends upward and is connected to an external servo drive motor. The technology of the servo drive motor driving the mold core 12 to rise and fall is existing technology. Therefore, its specific connection structure and lifting principle will not be described in detail in this specification. During operation, the servo drive motor provides precise power output to drive the mold core 12 to make a smooth reciprocating motion of rising and falling. When it goes down, it axially stretches the second preform 200 so that the second preform reaches the preset stretching ratio and shape, creating good conditions for the subsequent high-pressure inflation and expansion shaping inside the cavity, effectively ensuring the accuracy and overall molding quality of the blow molding of the plastic bottle 400.

[0105] like Figure 6As shown, the mold core 12 includes an air inlet channel 121 and an air outlet 122. The air outlet 122 is connected to the lower end of the air inlet channel 121. The upper end of the air inlet channel 121, away from the air outlet 122, is connected to an external air supply pipeline. The sealing connection, pipeline layout, and connection fixing method between the air inlet channel 121 and the external air supply pipeline all adopt existing mature technologies, so this specification will not elaborate further. During operation, the external air supply pipeline supplies gas to the air inlet channel 121. The gas flows downward along the air inlet channel 121 and is evenly blown out through the air outlet 122, entering the interior of the second preform 200. The expansion force of the gas expands the second preform 200 and tightly adheres it to the inner wall of the mold cavity, thereby completing the overall blow molding and shaping of the plastic bottle 400. The gas supply principle used in this solution adopts existing mature technologies, so this specification will not elaborate further.

[0106] like Figure 6 As shown, the ejector rod 13 is coaxially inserted inside the air inlet channel 121 of the mold core 12. The ejector rod 13 is always fixed and stationary and does not slide axially. The upper end of the ejector rod 13 passes through the mold core 12 and forms a precision sealed sliding fit with the mold core 12. One end of the ejector rod 13 that passes through the mold core 12 is fixedly connected to the transfer device inside the molding equipment. When the mold core 12 moves downward, it will not drive the ejector rod 13 to move. Only the servo mechanism drives the mold core 12 to make up-down axial sliding motion. Through the lifting displacement of the mold core 12 itself, the stretching and shaping of the second preform 200 and the opening and closing of the air inlet channel 121 and the air outlet 122 are completed.

[0107] like Figure 6 As shown, there are two first templates 14, which are symmetrically arranged on the outer periphery of the mold core 12. Each first template 14 is fixedly equipped with a driving cylinder on its outer side. The two sets of first templates 14 are driven by the extension and retraction of the cylinder to realize the action of closing towards each other and separating away from each other. After the two sets of first templates 14 are closed, their inner surfaces cooperate with the outer wall of the mold core 12 to jointly enclose and form the bottle mouth forming cavity of the plastic bottle body 400.

[0108] like Figure 6 As shown, the first lower mold 2 includes a first mold cavity 21 and a first feeding channel 22; the first lower mold 2 is stably installed and fixed on the worktable of the molding equipment. A heating wire assembly is pre-embedded inside the first lower mold 2. The heating wire is energized to heat the first mold cavity 21 to maintain a constant temperature and control the temperature, so as to meet the temperature conditions required for the injection molding of the preform. The heating wire is a conventional existing structure in the industry, so its specific arrangement and installation structure will not be described in detail in this application.

[0109] The upper end of the first mold cavity 21 is open, and the first feed channel 22 is connected to the side wall of the first mold cavity 21, such as Figure 2As shown, in the process of forming the first preform 100, the two sets of first templates 14 close downwards and press against the upper surface of the first lower mold 2. The mold core 12 moves down synchronously and is precisely inserted into the first mold cavity 21 for mold closing and positioning. The first extruder 6 conveys molten plastic raw material into the first mold cavity 21 through the first feeding channel 22 and cools to form the first preform 100.

[0110] like Figures 7 to 9 As shown, the lower mold base 4 includes a third template 41, a base 42, a third mold cavity 43, and a third feeding channel 44; wherein, the third mold cavity 43 and the third feeding channel 44 are integrally formed inside the base 42, adopting an internal flow channel and cavity layout, with a compact and regular structure. One end of the third feeding channel 44 is connected to the bottom of the third mold cavity 43 and the other end is connected to the outer wall of the base 42. The third template 41 is located on the upper part of the base 42. There are two third templates 41, which can move closer or further apart from each other. The two third templates 41 have the function of opening and closing with each other and separating with each other. They can be precisely aligned and clamped by a drive mechanism to meet the working conditions of mold closing and clamping, and mold separating and demolding.

[0111] When the second preform 200 is formed, the lower end of the upper mold 1 carrying the first preform 100 is inserted into the third mold cavity 43. After the upper mold 1 is in place, the lower outer wall of the first preform 100 and the inner wall of the third mold cavity 43 naturally surround each other to form a closed second molding cavity 431, providing an independent and regular molding space for secondary injection molding. At the same time, the two third mold plates 41 move towards each other synchronously to complete the mold closing and clamping. They precisely hold the upper part of the first preform 100 from the outside, playing the role of radial positioning, locking and limiting and sealing material blocking. This effectively prevents the preform from shifting, misaligning and overflowing during injection molding, and ensures the airtightness and molding accuracy of the second molding cavity 431.

[0112] The second lower mold 3 includes two second templates 31. The two second templates 31 are closed to form a second mold cavity 32. When the second preform 200 is formed, the upper mold 1 synchronously drives the second preform 200 to rise between the two second templates 31. When the plastic bottle body 400 is formed, the two second templates 31 are closed to wrap the second preform 200 in the second mold cavity 32.

[0113] Airflow is introduced into the second preform 200 through the air inlet channel 121 inside the mold core 12. Using a pneumatic expansion blow molding process, the preform is molded to conform to the inner wall of the second mold cavity 32. Simultaneously, under the combined action of blow molding tension and mold cavity shaping, the bottom of the bottle naturally forms a shape resembling... Figure 1The concave, thick-bottomed area shown in Figure a creates a thick-bottomed plastic bottle 400, which, from an external perspective, exhibits a noticeable height effect due to its thick bottom. Because the plastic particles used are high-transparency PET particles, a high-transparency, thick-bottomed plastic bottle 400 can be produced. The resulting plastic bottle 400 has a strong three-dimensional effect due to its thick bottom, and its overall visual texture closely resembles that of a high-transparency, thick-bottomed glass bottle. However, its production cost is far lower than that of a glass bottle. PET material has good toughness and impact resistance, and the thick-bottomed structure further enhances the bottom support strength, making it less prone to breakage and deformation. Unlike glass bottles, which are fragile, it is more durable and environmentally friendly.

[0114] The manufacturing process using the molding die in this embodiment includes the following steps:

[0115] S1, such as Figure 6 As shown, the transfer device of the molding equipment drives the upper mold 1 to move vertically downwards, and the upper mold 1 is inserted into the first cavity 21 of the first lower mold 2 from top to bottom and closes with the first lower mold 2.

[0116] S2, such as Figure 6 As shown, the first extruder 6 operates to inject the first lower die 2 into the mold, and after cooling, it forms the first preform 100.

[0117] Specifically, the first extruder 6 drives the extrusion head to move, so that the extrusion head is connected to the first feed channel 22 and molten PET material is extruded. The temperature control of the extrusion head is set in sections: 240°C for the rear section, 255°C for the middle section, and 265°C for the front section. The material is injected into the first cavity 21 of the first mold 2 through the gating channel at a uniform speed with an injection pressure of 90MPa~110MPa and an injection speed of 60mm / s~80mm / s.

[0118] A holding pressure of 50MPa to 60MPa and a holding time of 3s to 5s are used to ensure that the melt completely fills the cavity;

[0119] After the pressure holding is completed, the cooling and shaping stage begins. The cooling time is set to 12s to 18s. The molten plastic in the cavity is cooled gradually and evenly by relying on the circulating cooling water inside the mold to dissipate heat at a constant temperature.

[0120] S3, such as Figure 7 As shown, the second extruder 7 operates to re-inject the lower part of the first preform 100, and after cooling, it forms a second preform 200 with a thickened part 300 at the bottom.

[0121] Specifically, the second extruder 7 is located in the lower die holder 4, which is located below the second lower die 3, and the second preform 200 is formed in the lower die holder 4;

[0122] ① The upper mold 1 carrying the first blank 100 is moved above the lower mold base 4 and inserted into the third mold cavity 43 of the lower mold base 4 from top to bottom. The first blank 100 and the bottom of the third mold cavity 43 form a second molding cavity 431.

[0123] ② The servo motor drives the two third templates 41 to close the mold, and the third templates 41 abut against the circumference of the first blank body 100;

[0124] ③ The third mold cavity 43 heats and softens the portion of the first preform 100 located in the second molding cavity 431, so that the surface layer of the first preform 100 reaches a molten and compatible state, creating conditions for the hot-melt bonding of the new and old melts. The local heating temperature is 95-105℃, which only softens without damaging the original structure and shape of the first preform 100;

[0125] ④ The second extruder 7 operates to inject plastic into the second molding cavity 431. Molten plastic particles fill the second molding cavity 431 and combine with the first preform 100.

[0126] The extrusion head section temperatures of the second extruder are as follows: rear section 235℃, middle section 250℃, and front section 260℃.

[0127] With an injection pressure of 85-105MPa and an injection speed of 55-75mm / s, molten plastic is injected into the first molding cavity 211 through a dedicated flow channel. The molten material quickly fills the entire cavity and fully melts and fuses with the bottom of the heated and softened first preform 100, forming an integral structure.

[0128] A pressure of 45–55 MPa and a holding time of 12–15 seconds are used to compensate for shrinkage and prevent shrinkage marks and delamination at the joint.

[0129] ⑤ After cooling, a second preform 200 is produced;

[0130] After the injection molding pressure is maintained, the mold cooling water circulation is started to keep the first molding cavity 211 at a constant temperature for 10-16 seconds.

[0131] S4, such as Figure 7 and Figure 8 As shown:

[0132] ① The upper mold 1 carrying the second preform 200 is raised and detached from the third mold cavity 43;

[0133] ② The two second templates 31 of the second lower mold 3 are closed, and the main body of the second blank 200 is located in the second mold cavity 32;

[0134] ③ The upper mold 1 and the second lower mold 3 are closed together, and the main body of the second blank 200 is located in the second mold cavity 32;

[0135] S5. Heat the second mold cavity 32 to soften the second preform 200;

[0136] The second lower mold 3 has a built-in temperature control heating system that is activated to perform constant temperature heating on the second mold cavity 32, and to uniformly heat and keep the entire second preform 200 warm, so that the material of the second preform 200 reaches a highly elastic and softened state, and has good tensile and ductile properties.

[0137] S6, such as Figure 9 As shown, the mold core 12 of the upper mold 1 slowly descends, and the air intake channel 121 inside the mold core 12 is connected to the inner wall of the second preform 200, and low-pressure gas is introduced into the air intake channel 121.

[0138] Initially, low-pressure compressed gas is introduced to pre-inflate and support the interior of the second preform 200, so that the softened second preform 200 is initially stretched and fits the local surface of the cavity, preventing the second preform 200 from collapsing, wrinkling and deforming during the stretching process.

[0139] S7. The mold core 12 descends and elongates the second preform 200 until the lower part of the second preform 200 abuts the bottom of the second mold cavity 32, and high-pressure gas is introduced into the air inlet channel 121 for blow molding.

[0140] When the bottom of the second preform 200 reaches the bottom limit position of the second mold cavity 32, the axial stretching stops, and the system immediately switches the air supply mode, changing from low pressure to high pressure gas to be continuously blown in.

[0141] Under the action of high-pressure airflow, the softened second preform 200 expands outward evenly and fits tightly with the inner wall contour of the second mold cavity 32. It is shaped according to the mold cavity shape and simultaneously forms a concave thickened structure at the bottom of the bottle.

[0142] S8, such as Figure 10 As shown, after blow molding is completed, the mold core 12 rises and resets, forming a thick-bottomed plastic bottle body 400.

[0143] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A plastic bottle manufacturing process, characterized in that, Includes the following steps: S1. Insert the upper mold (1) from top to bottom into the first cavity (21) of the first lower mold (2) and close the mold with the first lower mold (2); S2. The first extruder (6) operates to inject the first lower die (2) into the mold, and after cooling, it forms the first preform (100). S3. The second extruder (7) operates to re-inject the lower part of the first preform (100) and after cooling, it forms a second preform (200) with a thickened part (300) at the bottom. S4. The upper mold (1) and the second lower mold (3) are closed together, and the main body of the second blank (200) is located in the second mold cavity (32); S5. Heat the second mold cavity (32) to soften the second preform (200); S6. The mold core (12) of the upper mold (1) descends, and the air inlet channel (121) inside the mold core (12) is connected to the inner wall of the second preform (200), and low-pressure gas is passed through the air inlet channel (121). S7. The mold core (12) descends and elongates the second preform (200) until the lower part of the second preform (200) abuts the bottom of the second mold cavity (32), and high-pressure gas is introduced into the air inlet channel (121) for blow molding; S8. After blow molding is completed, the mold core (12) rises and resets to form a thick-bottomed plastic bottle body (400).

2. The plastic bottle manufacturing process according to claim 1, characterized in that, In step S3, the second extruder (7) is located in the first lower die (2), and the second preform (200) is formed in the first lower die (2).

3. The plastic bottle manufacturing process according to claim 2, characterized in that, Step S3 further includes the following steps: ① The slider (5) inside the first lower mold (2) descends, and the upper part of the slider (5) and the lower part of the first blank (100) form the first molding cavity (211); ② The area of ​​the first mold cavity (21) located in the first molding cavity (211) is heated and softened to soften the portion of the first preform (100) located in the first molding cavity (211); ③ The second extruder (7) operates to inject the first molding cavity (211) with molten plastic particles, which fill the first molding cavity (211) and combine with the first preform (100); ④ After cooling, a second embryo (200) is produced.

4. The plastic bottle manufacturing process according to claim 1, characterized in that, In step S3, the second extruder (7) is located in the lower die holder (4), the lower die holder (4) is located below the second lower die (3), and the second preform (200) is formed in the lower die holder (4).

5. The plastic bottle manufacturing process according to claim 4, characterized in that, Step S3 further includes the following steps: ① Insert the upper mold (1) carrying the first preform (100) into the third mold cavity (43) of the lower mold base (4) from top to bottom, and the first preform (100) and the bottom of the third mold cavity (43) form a second molding cavity (431); ② The two third templates (41) are closed, and the third templates (41) abut against the periphery of the first blank (100); ③ The third mold cavity (43) heats and softens the portion of the first preform (100) located in the second molding cavity (431); ④ The second extruder (7) operates to inject plastic into the second molding cavity (431). The molten plastic particles fill the second molding cavity (431) and combine with the first preform (100). ⑤ After cooling, a second embryo (200) is produced.

6. The plastic bottle manufacturing process according to claim 5, characterized in that, Step S4 also includes the following steps: ① The upper mold (1) carrying the second preform (200) is raised and detached from the third mold cavity (43); ② The two second templates (31) of the second lower mold (3) are closed, and the main body of the second blank (200) is located in the second mold cavity (32).

7. The plastic bottle manufacturing process according to claim 1, characterized in that, The plastic bottle body (400) is made of PET high-transparency plastic particles.

8. A plastic bottle forming mold, comprising an upper mold (1), a first lower mold (2), and a second lower mold (3) as described in any one of claims 1-7, characterized in that, The upper mold (1) includes a first module (11), a mold core (12), an ejector pin (13), and a first template (14); The mold core (12) penetrates the first module (11). The mold core (12) includes an air inlet channel (121) and an air outlet (122). The air outlet (122) is connected to the lower end of the air inlet channel (121). The push rod (13) is located in the air inlet channel (121) and can be inserted into or removed from the air outlet (122). There are two first templates (14) located around the mold core (12). After the two first templates (14) are closed, they form a bottle mouth forming area of ​​the plastic bottle body (400) between the mold core (12) and the outer wall of the mold core (12). The first lower mold (2) includes a first mold cavity (21). When forming the first blank (100), the lower part of the first template (14) abuts against the upper part of the first lower mold (2) and the mold core (12) is inserted into the first mold cavity (21). The second lower mold (3) includes two second templates (31), which are joined together to form a second mold cavity (32). When molding the plastic bottle body (400), the lower part of the first template (14) abuts against the upper part of the second lower mold (3) and the mold core (12) is inserted into the second mold cavity (32).

9. A plastic bottle molding die according to claim 8, characterized in that, The first lower mold (2) also includes a first feeding channel (22), a guide groove (23), and a second feeding channel (24). The first feeding channel (22) and the second feeding channel (24) are located on both sides of the first lower mold (2). The first feeding channel (22) is connected to the side wall of the first mold cavity (21). A slider (5) is slidably connected in the guide groove (23). The slider (5) includes a boss (51) and a fourth feeding channel (52). The lower part of the first mold cavity (21) is open. The upper end of the boss (51) is embedded in the lower opening of the first mold cavity (21) and blocks the opening. One end of the fourth feeding channel (52) is connected to the bottom of the first mold cavity (21) and the other end is connected to the outer wall of the slider (5). When forming the first blank (100), the upper part of the slider (5) abuts against the top of the guide groove (23), and the fourth feeding channel (52) blocks the second feeding channel (24); When forming the second preform (200), the upper part of the slider (5) is separated from the top of the guide groove (23), and a first forming cavity (211) is formed between the upper part of the slider (5) and the lower part of the first preform (100). The fourth feeding channel (52) is connected to the second feeding channel (24).

10. A plastic bottle molding die according to claim 8, characterized in that, It also includes a lower mold base (4), which includes a third template (41), a base (42), a third mold cavity (43), and a third feeding channel (44); The third mold cavity (43) and the third feeding channel (44) are both located inside the base (42). One end of the third feeding channel (44) is connected to the bottom of the third mold cavity (43) and the other end is connected to the outer wall of the base (42). The third template (41) is located on the upper part of the base (42). There are two third templates (41) that can be close to or far from each other. When forming the second preform (200), the lower end of the upper mold (1) carrying the first preform (100) is inserted into the third mold cavity (43), and a second forming cavity (431) is formed between the lower part of the first preform (100) and the third mold cavity (43). The two third molds (41) close together and clamp the first preform (100).

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