A forming device for food grade plastic bottles

Abstract

The application relates to the technical field of plastic bottle forming, in particular to a food-grade plastic bottle forming device, which comprises a fixing base, a mold arranged on one side of the fixing base, a blow molding mechanism used for blowing gas into the inside of a bottle blank, a negative pressure mechanism used for providing a negative pressure environment for the outside of the bottle blank, and a lifting mechanism used for controlling the up-and-down movement of the blow molding mechanism and the negative pressure mechanism. The food-grade plastic bottle forming device can provide positive and negative pressures for the two sides of the bottle blank through the cooperation of the blow molding mechanism and the negative pressure mechanism, on one hand, the pressures on the two sides of the multilayer bottle blank are more balanced, and the situation that the inner layer of the bottle blank is excessively pressed due to the independent pressing of the inner layer is avoided; on the other hand, the pressures provided on the two sides are dispersed, the gas pressure in the inside of the bottle blank is reduced, the situation that the thickness of the inside of the bottle blank is uneven due to the excessive pressure is avoided, the wall thickness of the formed plastic bottle is more uniform, and the quality of the plastic bottle is improved.

Description

Technical Field

[0001] This invention relates to the field of plastic bottle molding technology, specifically to a molding apparatus for food-grade plastic bottles. Background Technology

[0002] Plastic bottles are generally made from polyester (PET), polyethylene (PE), or polypropylene (PP) as raw materials, with the addition of appropriate organic solvents, and then blow-molded. Food-grade plastic bottles have strict material requirements and often employ a multi-layered structure to save on finished products. The innermost layer is made of food-grade raw materials, the outermost layer is a decorative layer, and the middle layer can be filled with recycled plastic, achieving the goals of saving and environmental protection.

[0003] In the blow molding process of multi-layer food-grade plastic bottles, airflow enters the preform downwards along the air blowing tube, causing the preform to expand. During this process, problems such as unidirectional airflow and excessive air pressure can lead to uneven bottle wall thickness and excessive inner layer compression, resulting in excessively thin walls, thus affecting the quality of the molded plastic bottle. Therefore, we propose a molding device for food-grade plastic bottles. Summary of the Invention

[0004] The purpose of this invention is to provide a molding apparatus for food-grade plastic bottles, which solves the problem of poor quality in the blow molding of multi-layer food-grade plastic bottles.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A molding apparatus for food-grade plastic bottles, including a fixing base;

[0007] The mold is disposed on one side of the fixed base;

[0008] Blow molding mechanism, used to blow gas into the preform;

[0009] The negative pressure mechanism is used to provide a negative pressure environment for the outside of the preform.

[0010] A lifting mechanism is used to control the up-and-down movement of the blow molding mechanism and the negative pressure mechanism;

[0011] The mold has a semi-mold cavity on one side, the top of the semi-mold cavity penetrates the mold and is connected to an air blowing port, the mold has a cavity inside, and the top of the mold has an air extraction port connected to the cavity. The semi-mold cavity and the cavity are connected through capillary pores.

[0012] Preferably, the blow molding mechanism includes an air pump, which is fixedly mounted on the fixed base. The output end of the air pump is connected to a first connecting pipe through an air outlet pipe. The bottom end of the first connecting pipe is connected to a first horizontal pipe, and the bottom of the first horizontal pipe is connected to an air blowing pipe, which is used to insert into the air blowing port.

[0013] Preferably, a rotating shaft is rotatably connected to the inner wall of the air blowing pipe, and multiple fan blades are fixedly connected to the surface of the rotating shaft;

[0014] The outer peripheral wall of the air blowing pipe is provided with a circumferential air outlet, and the bottom of the pipe is provided with a bottom air outlet.

[0015] Preferably, the negative pressure mechanism includes a diverter pipe, one end of which is connected to the input end of the air pump, and the other end is forked and connected to two second connecting pipes. The bottom end of the second connecting pipe is connected to a second horizontal pipe, and the bottom of the second horizontal pipe is connected to a suction pipe, which is used to be inserted into the suction port.

[0016] Preferably, the extraction pipe is provided with a sealing device to improve the sealing between the extraction pipe and the extraction port.

[0017] Preferably, the sealing device includes a housing, which is slidably fitted onto the air extraction pipe. An opening is provided on the outer peripheral wall of the housing, and an airbag is fixedly fitted on the outer peripheral wall of the housing outside the opening.

[0018] Preferably, a piston plate is slidably connected to the inner wall of the housing, one end of the piston plate is elastically connected to the inner wall of the housing via a spring, and a pressure rod is fixedly connected to the top end of the piston plate. The top end of the pressure rod passes through the housing and is fixedly connected to a pressure plate.

[0019] Preferably, an abutment plate is fixedly connected to the housing, and the bottom end of the abutment plate is used to contact the top of the mold.

[0020] Preferably, a plurality of sliding plates are fixedly connected to the inner peripheral wall of the housing, and the sliding plates are slidably connected to the inner wall of the air extraction pipe.

[0021] Preferably, the lifting mechanism includes a mounting plate, one end of which is fixedly connected to the fixed base, an electric push rod is fixedly mounted on the mounting plate, the output end of the electric push rod is fixedly connected to the lifting plate, and the first horizontal tube and the second horizontal tube are both fixedly mounted at the bottom of the lifting plate.

[0022] By employing the above technical solution, the present invention provides a molding apparatus for food-grade plastic bottles. It possesses at least the following beneficial effects:

[0023] (1) The molding device for the food-grade plastic bottle, through the cooperation of the blow molding mechanism and the negative pressure mechanism, can provide positive and negative pressure to both sides of the preform. On the one hand, it makes the pressure on both sides of the multi-layer preform more balanced, avoiding the situation where the inner layer of the preform is over-pressed due to pressure alone; on the other hand, by providing pressure on both sides, the pressure can be dispersed, reducing the air pressure supplied inside the preform, thereby avoiding the situation where the thickness inside the preform is uneven due to excessive pressure, thus making the wall thickness of the molded plastic bottle more uniform and improving the quality of the plastic bottle.

[0024] (2) The molding device for the food-grade plastic bottle can be set with capillary pores to cooperate with the negative pressure mechanism to provide a negative pressure environment for the outside of the bottle blank. The plastic bottle blank cannot pass through the capillary pores due to surface tension, which does not affect the molding effect. By setting a sealing device, the air extraction pipe and the air extraction port can be sealed to prevent the negative pressure leakage in the cavity and ensure the effect of negative pressure adsorption. Attached Figure Description

[0025] The accompanying drawings, which are provided to further illustrate the invention, constitute a part of this application:

[0026] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the internal structure of the mold in an embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of the lifting mechanism in an embodiment of the present invention;

[0029] Figure 4 This is a schematic diagram of the blow molding mechanism in an embodiment of the present invention;

[0030] Figure 5 This is a schematic diagram of the air blowing pipe in an embodiment of the present invention;

[0031] Figure 6 This is a schematic diagram of the fan blades in an embodiment of the present invention;

[0032] Figure 7 This is a schematic diagram showing the connection between the air extraction pipe and the mold in an embodiment of the present invention;

[0033] Figure 8 for Figure 7 Enlarged view of the structure at point A in the middle;

[0034] Figure 9 This is a schematic diagram of the shell and airbag in an embodiment of the present invention.

[0035] In the diagram: 1. Fixed base; 2. Mold; 201. Semi-mold cavity; 202. Air inlet; 203. Cavity; 204. Air extraction port; 3. Lifting mechanism; 301. Mounting plate; 302. Electric push rod; 303. Lifting plate; 4. Blow molding mechanism; 401. Air pump; 402. Air outlet pipe; 403. First connecting pipe; 404. First horizontal pipe; 405. Air inlet pipe; 406. Circumferential air outlet ; 407, Bottom air outlet; 408, Support; 409, Rotating shaft; 4010, Fan blade; 5, Negative pressure mechanism; 501, Diverter pipe; 502, Second connecting pipe; 503, Second horizontal pipe; 504, Suction pipe; 505, Housing; 506, Airbag; 507, Piston plate; 508, Pressure rod; 509, Pressure plate; 5010, Abutment plate; 5011, Slide plate; 5012, Spring. Detailed Implementation

[0036] 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.

[0037] Food-grade plastic bottles have a multi-layered structure, with the innermost layer being food-grade, the middle layer being recycled plastic, and the outermost layer being a decorative layer. During blow molding, airflow enters the preform from the blow molding tube, causing the preform to expand. In this process, problems such as unidirectional airflow and excessive air pressure can lead to uneven wall thickness of the plastic bottle, affecting the quality of blow molding.

[0038] For this purpose, please refer to Figures 1-9 The present invention provides a technical solution:

[0039] A molding device for food-grade plastic bottles includes a fixed base 1, a mold 2 is provided on one side of the fixed base 1, and a blow molding mechanism 4 and a negative pressure mechanism 5 are provided above the mold 2. The blow molding mechanism 4 is used to blow gas into the bottle preform, and the negative pressure mechanism 5 is used to provide a negative pressure environment for the outside of the bottle preform. A lifting mechanism 3 is provided on the fixed base 1 to control the up and down movement of the blow molding mechanism 4 and the negative pressure mechanism 5 to realize the docking of the blow molding mechanism 4 and the negative pressure mechanism 5 with the mold 2.

[0040] Please see Figures 1-3There are two molds 2. After the two molds 2 are closed, a complete mold cavity is formed for the molding of plastic bottles. After the mold is opened, the molded plastic bottles fall out of the mold cavity to realize the discharge. Specifically, each of the two molds 2 has a semi-mold cavity 201 on one side opposite to the mold. The top of the semi-mold cavity 201 penetrates through the mold 2 and is connected to an air blowing port 202, which is used to cooperate with the blow molding mechanism 4 to blow gas into the preform inside the mold cavity. The mold 2 has a cavity 203 inside, and the top of the mold 2 has an air extraction port 204 connected to the cavity 203, which is used to cooperate with the negative pressure mechanism 5 to draw gas from the cavity 203 and provide a negative pressure environment. The semi-mold cavity 201 and the cavity 203 are connected by capillary pores with a diameter between 0.1μm and 0.5μm, which allows gas to pass through normally. In the negative pressure environment, the outer side of the preform will be adsorbed onto the inner wall of the mold cavity. Due to the surface tension, the plastic preform cannot pass through the capillary pores, so it can stick tightly to the inner wall of the mold cavity to form a plastic bottle shape.

[0041] Please continue reading. Figure 3 The lifting mechanism 3 includes a mounting plate 301. One end of the mounting plate 301 is fixedly connected to the fixed base 1. An electric push rod 302 is fixedly mounted on the mounting plate 301. The output end of the electric push rod 302 is fixedly connected to the lifting plate 303. When the electric push rod 302 is started, it can drive the lifting plate 303 to move up and down, thereby controlling the docking of the blow molding mechanism 4 and the negative pressure mechanism 5 with the mold 2.

[0042] Please see Figures 3-4 The blow molding mechanism 4 includes an air pump 401, which is fixedly mounted on a fixed base 1. The output end of the air pump 401 is connected to a first connecting pipe 403 via an air outlet pipe 402. The bottom end of the first connecting pipe 403 is connected to a first horizontal pipe 404. The first connecting pipe 403 is fixedly mounted on the inner wall of the lifting plate 303, and the first horizontal pipe 404 is fixedly mounted on the bottom of the lifting plate 303. The air outlet pipe 402 is a flexible hose to accommodate the lifting movement of the lifting plate 303. The bottom of the first horizontal pipe 404 is connected to a blowing pipe 405, which is inserted into the blowing port 202. Multiple mold cavities and multiple blowing pipes 405 are available, allowing for simultaneous blow molding of multiple preforms and improving production efficiency.

[0043] In this embodiment, the outer peripheral wall of the blowing pipe 405 is provided with multiple circumferential air outlets 406, and the bottom of the pipe is provided with multiple bottom air outlets 407, so that gas can be blown out from multiple directions to disperse the air pressure in a single direction and prevent uneven bottle wall thickness. A rotating shaft 409 is rotatably connected to the inner wall of the blowing pipe 405, and multiple fan blades 4010 are fixedly connected to the surface of the rotating shaft 409. When the gas passes through the fan blades 4010, it will drive the fan blades 4010 to rotate, which will disperse the airflow and further disperse the gas pressure, so as to avoid the situation where the pressure in the gas flow direction is too large, resulting in excessive uneven bottle wall thickness on that side. In addition, a bracket 408 is fixedly connected to the inner wall of the blowing pipe 405. The inner wall of the bracket 408 is rotatably connected to the top end of the rotating shaft 409 to support the rotating shaft 409 and improve its stability.

[0044] Please see Figure 4 The negative pressure mechanism 5 includes a diversion pipe 501. One end of the diversion pipe 501 is connected to the input end of the air pump 401, and the other end is forked and connected to two second connecting pipes 502. The bottom end of the second connecting pipe 502 is connected to a second horizontal pipe 503. Both second connecting pipes 502 are fixedly installed on the inner wall of the lifting plate 303. The second horizontal pipe 503 is fixedly installed at the bottom of the lifting plate 303 and can move up and down with the lifting plate 303. The diversion pipe 501 is a flexible hose to accommodate the up and down movement of the second connecting pipe 502 and the second horizontal pipe 503. The bottom of the second horizontal pipe 503 is connected to a suction pipe 504, which is inserted into the suction port 204 to suck up the gas in the cavity 203. During suction, the gas in the mold cavity will enter the cavity 203 through the capillary pores, so that the preform and the inner wall of the mold cavity are in a negative pressure state, thereby adsorbing the preform onto the inner wall of the mold cavity. The blow molding mechanism 4 and the negative pressure mechanism 5 operate simultaneously, providing positive and negative pressure to both sides of the preform. On the one hand, this makes the pressure on both sides of the multi-layer preform more balanced, avoiding the situation where the inner layer of the preform is over-compressed due to pressure alone. On the other hand, by providing pressure on both sides, the pressure can be dispersed, reducing the air pressure supplied inside the preform, thereby avoiding the situation where the thickness inside the preform is uneven due to excessive pressure.

[0045] Please see Figures 7-9 A sealing device is provided on the suction pipe 504 to improve the sealing between the suction pipe 504 and the suction port 204, and to prevent negative pressure leakage, which would affect the adsorption effect.

[0046] Specifically, the sealing device includes a housing 505, which is slidably fitted onto the suction pipe 504. An opening is provided on the outer peripheral wall of the housing 505, and an air bladder 506 is fixedly fitted onto the outer peripheral wall of the housing 505 outside the opening. The air bladder 506 inflates to seal the suction port 204. A piston plate 507 is slidably connected to the inner wall of the housing 505. The piston plate 507 moves within the housing 505, compressing the gas inside and allowing it to enter the air bladder 506. A pressure rod 508 is fixedly connected to the top of the piston plate 507. The top of the pressure rod 508 penetrates the housing 505 and is fixedly connected to a pressure plate 509. A spring 5012 is fitted around the pressure rod 508. One end of the piston plate 507 is elastically connected to the inner wall of the housing 505 via the spring 5012. By providing the spring 5012, the pressure plate 509 can automatically reset after the external force is removed.

[0047] Furthermore, an abutment plate 5010 is fixedly connected to the housing 505. The bottom end of the abutment plate 5010 is used to contact the top of the mold 2 to achieve positioning, so that the airbag 506 is aligned with the inside of the air extraction port 204, thereby ensuring a sealing effect. In addition, after positioning, the air extraction pipe 504 continues to move downward, which will drive the piston plate 507 to move downward through the pressure plate 509 and the pressure rod 508, thereby achieving automatic compression of the gas inside the housing 505.

[0048] In addition, multiple sliding plates 5011 are fixedly connected to the inner peripheral wall of the housing 505. The sliding plates 5011 are slidably connected to the inner wall of the exhaust pipe 504 to improve the stability between the housing 505 and the exhaust pipe 504.

[0049] When the food-grade plastic bottle molding device of the present invention is in use, when the mold 2 receives the preform and moves to the bottom of the blow molding mechanism 4 and the negative pressure mechanism 5, the electric push rod 302 is activated. The output end of the electric push rod 302 drives the lifting plate 303 to move downward. The lifting plate 303 simultaneously drives the first horizontal tube 404, the second horizontal tube 503, the first connecting tube 403 and the second connecting tube 502 to move downward. The first horizontal tube 404 simultaneously drives the multiple air blowing tubes 405 at its bottom to move downward, so that the air blowing tubes 405 enter the air blowing port 202 at the top of the mold 2. The second horizontal tube 503 simultaneously drives the multiple air extraction tubes 504 at its bottom to move downward, so that the air extraction tubes 504 enter the air extraction port 204 at the top of the mold 2.

[0050] During the movement of the suction pipe 504, the sealing device on it moves downwards synchronously. When the abutment plate 5010 on the sealing device contacts the top of the mold 2, the abutment plate 5010 and the housing 505 fixed thereto stop moving. At this time, the suction pipe 504 continues to move downwards and slides downwards relative to the housing 505. The suction pipe 504 drives the pressure plate 509 to move downwards. The pressure plate 509 drives the piston plate 507 to move downwards through the pressure rod 508, compressing the gas inside the housing 505 and causing the gas to enter the air bladder 506. This causes the air bladder 506 to inflate, and the inflated air bladder 506 presses against the inner wall of the suction port 204, achieving a sealing effect.

[0051] Then, the air pump 401 is started. The input end of the air pump 401 draws in air through the diversion pipe 501. The end of the diversion pipe 501 draws in air through the two second connecting pipes 502 and the two second horizontal pipes 503 respectively. The two second horizontal pipes 503 simultaneously draw in the gas in the cavities 203 of the multiple shells 505 through multiple suction pipes 504. As a result, the gas in the semi-mold cavity 201 enters the cavity 203 through the capillary pores. The preform and the inner wall of the semi-mold cavity 201 are in a negative pressure state, which in turn draws the outer wall of the preform outward.

[0052] At the same time, the output end of the air pump 401 discharges the gas drawn in through the air outlet pipe 402. The discharged gas enters multiple air blowing pipes 405 through the first connecting pipe 403 and the first horizontal pipe 404 in sequence, and then enters the bottle preform in multiple half mold cavities 201 through the multiple air blowing pipes 405. After the gas is blown into the bottle preform, it bulges up and is formed by the mold 2.

[0053] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0054] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A molding apparatus for food-grade plastic bottles, characterized in that, include: Fixed base (1); The mold (2) is disposed on one side of the fixed base (1); Blow molding mechanism (4) is used to blow gas into the preform; The negative pressure mechanism (5) is used to provide a negative pressure environment for the outside of the preform; The lifting mechanism (3) is used to control the up and down movement of the blow molding mechanism (4) and the negative pressure mechanism (5); The mold (2) has a half-mold cavity (201) on one side, the top of the half-mold cavity (201) penetrates the mold (2) and is connected to an air blowing port (202), the mold (2) has a cavity (203) inside, and the top of the mold (2) has an air extraction port (204) connected to the cavity (203). The half-mold cavity (201) and the cavity (203) are connected through capillary pores. The blow molding mechanism (4) includes an air blowing pipe (405) for insertion into the air blowing port (202); The negative pressure mechanism (5) includes an air extraction pipe (504) for insertion into the air extraction port (204).

2. The forming apparatus for food-grade plastic bottles according to claim 1, characterized in that, The blow molding mechanism (4) also includes an air pump (401), which is fixedly installed on the fixed base (1). The output end of the air pump (401) is connected to a first connecting pipe (403) through an air outlet pipe (402). The bottom end of the first connecting pipe (403) is connected to a first horizontal pipe (404), and the bottom of the first horizontal pipe (404) is connected to an air blowing pipe (405).

3. The forming apparatus for food-grade plastic bottles according to claim 2, characterized in that, A rotating shaft (409) is rotatably connected to the inner wall of the air blowing pipe (405), and a plurality of fan blades (4010) are fixedly connected to the surface of the rotating shaft (409). The air blowing pipe (405) has a circumferential air outlet (406) on its outer peripheral wall and a bottom air outlet (407) at its bottom.

4. The forming apparatus for food-grade plastic bottles according to claim 2, characterized in that, The negative pressure mechanism (5) also includes a diversion pipe (501), one end of which is connected to the input end of the air pump (401), and the other end is bifurcated and connected to two second connecting pipes (502). The bottom end of the second connecting pipe (502) is connected to a second horizontal pipe (503), and the bottom of the second horizontal pipe (503) is connected to the suction pipe (504).

5. The forming apparatus for food-grade plastic bottles according to claim 4, characterized in that, The extraction pipe (504) is equipped with a sealing device to improve the sealing between the extraction pipe (504) and the extraction port (204).

6. The forming apparatus for food-grade plastic bottles according to claim 5, characterized in that, The sealing device includes a housing (505), which is slidably sleeved on the air extraction pipe (504). An opening is provided on the outer peripheral wall of the housing (505), and an airbag (506) is fixedly sleeved on the outer peripheral wall of the housing (505) outside the opening.

7. The forming apparatus for food-grade plastic bottles according to claim 6, characterized in that, A piston plate (507) is slidably connected to the inner wall of the housing (505). One end of the piston plate (507) is elastically connected to the inner wall of the housing (505) through a spring (5012). A pressure rod (508) is fixedly connected to the top end of the piston plate (507). The top end of the pressure rod (508) passes through the housing (505) and is fixedly connected to a pressure plate (509).

8. The forming apparatus for food-grade plastic bottles according to claim 7, characterized in that, An abutment plate (5010) is fixedly connected to the housing (505), and the bottom end of the abutment plate (5010) is used to contact the top of the mold (2).

9. The forming apparatus for food-grade plastic bottles according to claim 7, characterized in that, Multiple sliding plates (5011) are fixedly connected to the inner peripheral wall of the housing (505), and the sliding plates (5011) are slidably connected to the inner wall of the exhaust pipe (504).

10. The forming apparatus for food-grade plastic bottles according to claim 4, characterized in that, The lifting mechanism (3) includes a mounting plate (301), one end of which is fixedly connected to the fixed base (1). An electric push rod (302) is fixedly installed on the mounting plate (301), and the output end of the electric push rod (302) is fixedly connected to a lifting plate (303). The first horizontal tube (404) and the second horizontal tube (503) are both fixedly installed at the bottom of the lifting plate (303).

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