Multi-layer continuous forming process for plastic bottles

Abstract

A multi-layer continuous forming process for plastic bottles, comprising: (1) parison discharge; (2) initial parison sealing; (3) bottle body forming and filling; (4) first bottle body sealing; (5) parison sealing; (6) product chain formation; and (7) positioning before mold closing: when a main mold fixture clamps and lowers the product chain to align with a mold closing position, step (3) is repeated, and meanwhile, the main mold fixture is opened and moved to a position corresponding to the previous product chain and is then closed; and step (4) to step (7) are repeated to form a cycle so as to realize continuous production of plastic bottles. The present invention improves the production efficiency and the productivity.

Description

Plastic bottle multi-layer continuous molding process

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on March 6, 2024, with application number 2024102522071 and invention name “Multi-layer continuous molding process for plastic bottles”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The invention relates to the technical field of plastic processing, in particular to a multi-layer continuous molding process for plastic bottles. Background Art

[0003] At present, the molding of plastic bottles adopts single-layer mold molding technology. During the molding process of plastic bottles, it is necessary to configure a head mold clamp and a main mold clamp to continuously clamp the preform. For example, Chinese patent (CN111483153B) discloses a continuous production process for plastic bottles, which belongs to the field of BFS equipment plastic bottle production technology. (1) Tube blank discharge; (2) Initial sealing of the tube blank; (3) Bottle body molding and filling: After the hot melt tube blank reaches the mold clamping position, the mold is clamped: the mold includes a head mold and a main mold that can be opened and closed independently. The main mold is clamped and the bottle body is molded; the head mold is in the mold open state, and the filling tube is filled with liquid medicine; the clamp opens the mold and moves upward; (4) Bottle mouth is sealed; (5) Tube blank is sealed; (6) Product chain molding; Repeat steps (3) to (6) to form a cycle to realize the continuous production process of plastic bottles. The present invention realizes a continuous production process of plastic bottles. The filling tube is arranged in the tube embryo. The plastic bottle molding and filling are integrated and completed. The filling is always in a closed state. During the plastic bottle molding process, the tube embryo is always in a sealed state, which can maintain good sterility and avoid the risk of contamination.

[0004] The above process can only form one row of plastic bottles at a time, which is inefficient. When forming a row of bottles, a pair of head mold clamps must be formed in the product chain to clamp the waste area. In addition, because the head mold clamp spans the mold and pulls the parison downward, the wall thickness of the head mold clamp must be at least 12mm to meet production requirements. This leads to low material utilization. In the event of an equipment malfunction, the head mold clamp spanning the mold can easily cause a collision with the mold, resulting in damage to the high-value mold and poor equipment stability. Summary of the Invention

[0005] The purpose of the present invention is to solve the problems existing in the prior art and provide a multi-layer continuous molding process for plastic bottles, thereby improving production efficiency and increasing production capacity.

[0006] The present invention provides a multi-layer continuous molding process for plastic bottles, comprising the following steps:

[0007] (1) Tube blank discharge: The extruder extrude the hot melt tube blank, the filling tube is inserted into the extruder, and the filling tube extends into the hot melt tube blank;

[0008] (2) Initial sealing of the tube embryo: the main mold clamp closes the mold to seal the hot melt tube embryo, and tightens the hot melt tube embryo to move downward;

[0009] (3) Bottle body forming and filling: After the hot melt tube embryo reaches the main mold clamping position, the mold is clamped: the mold includes a head mold, a first main mold and a second main mold that can be opened and closed independently, the second main mold is clamped, and the second bottle body is formed; the first main mold and the head mold are in the open mold state, and the filling tube is filled with liquid medicine; after the second bottle body is filled, the first main mold is clamped to seal the second bottle body while the first bottle body is formed; the head mold is in the open mold state, and the filling tube is filled with liquid medicine;

[0010] (4) Sealing the first bottle: After filling is completed, the head mold is closed and the mouth of the first bottle is sealed;

[0011] (5) Tube blank sealing: the head mold clamp closes the mold and clamps the formed product chain;

[0012] (6) Product chain forming: The mold, main mold fixture and head mold fixture move down together to the mold opening position. The mold opens, and the head mold fixture opens in sequence. It moves up synchronously with the mold and resets to the mold closing position. The main mold fixture continues to clamp the product chain and moves down, stretching the parison to prevent it from shaking left and right due to the demoulding force.

[0013] (7) Positioning before mold closing: When the main mold fixture clamps the product chain and moves it down to match the mold closing position, repeat step (3), and at the same time, the main mold fixture opens and moves up to the position corresponding to the previous product chain, and the main mold fixture closes the mold;

[0014] Repeat steps (4) to (7) to form a cycle to achieve continuous production of plastic bottles.

[0015] A second bottle body cavity is set in the second main mold, and a first bottle body cavity and a second bottle mouth cavity are set in the first main mold from top to bottom, the second bottle mouth cavity corresponds to the second bottle body cavity, and a first bottle mouth cavity is set in the head mold corresponding to the first bottle body cavity. Temperature probes are set on the first main mold and the second main mold, and the temperature probes are respectively connected to the first bottle body cavity and the second bottle body cavity.

[0016] The head mold fixture can be embedded in the head mold, and the main mold fixture can be embedded in the second main mold.

[0017] During the bottle body forming, filling and bottle mouth sealing, the mold continuously pulls the hot melt tube blank downward.

[0018] The method also includes a collecting tube and a monitoring device. The collecting tube is placed in the extrusion device and passes through the extrusion device. The bottom end of the collecting tube is connected to the tube embryo, and the top end of the collecting tube is connected to the monitoring device.

[0019] When the hot melt tube blank is sealed, the main mold fixture is in a mold closing state and the head mold fixture is in a mold opening state.

[0020] The main mold fixture is provided with a contoured cooling cavity, which can perform secondary cooling on the thermoformed plastic bottles, ensuring that the product chain is thoroughly cooled and avoiding stretching and deformation due to its own weight.

[0021] A first drive device is provided for the head mold fixture, and a second drive device is provided for the main mold fixture. The first and second drive devices are independently provided. The independent drive devices for the head mold fixture and the main mold fixture better accommodate their movement and allow for adjustment of their positions to accommodate the production of bottles of varying specifications.

[0022] The master mold fixture is equipped with a compressed air channel and a water cooling channel. The compressed air channel communicates with the contour cooling cavity, while the water cooling channel is located in parallel with the compressed air channel. The compressed air channel is used to cool areas of the plastic bottle that are not fully enclosed by the contour cooling cavity. The water cooling channel cools the clean air entering the compressed air channel of the master mold fixture, thereby achieving cold air output and simultaneously cooling the master mold fixture.

[0023] The thickness of the head mold fixture is 0.5-3 mm. In the prior art, because the head mold fixture spans the mold and pulls the parison downward, the wall thickness of the head mold fixture must be at least 12 mm to meet production requirements, resulting in low material utilization. The head mold fixture in this application moves synchronously with the head mold and does not need to span the mold. Therefore, the thickness can be set to less than 3 mm, improving material utilization.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention forms the second bottle body by the second main mold, and then seals the second bottle body by the first main mold while the first bottle body is being formed, thereby improving production efficiency and capacity.

[0026] 2. The head mold fixture is placed above the head mold and can be used with the head mold; the main mold fixture is placed below the second main mold and can be used with the second main mold. The head mold fixture and the head mold move synchronously up and down, without having to cross the mold to run, avoiding collision with the mold and improving the stability of the equipment operation.

[0027] 3. A contoured cooling cavity is provided on the main mold fixture. This cavity provides secondary cooling for the thermoformed plastic bottles, ensuring thorough cooling of the product chain and preventing stretching and deformation due to its own weight. Furthermore, the contoured clamping of the product chain effectively maintains its grip, preventing deformation caused by the tensile forces of the mold release.

[0028] 4. A first drive device is provided for the head mold fixture, and a second drive device is provided for the main mold fixture. The first and second drive devices are provided independently of each other. The independent drive devices for the head mold fixture and the main mold fixture better adapt to the movement of the head mold fixture and the main mold fixture. The position of the head mold fixture and the main mold fixture can also be adjusted according to different bottle specifications to accommodate the production of different bottle shapes.

[0029] 5. The thickness of the head mold fixture is 0.5-3 mm. In the prior art, because the head mold fixture spans the mold and pulls the parison downward, the wall thickness of the head mold fixture must be at least 12 mm to meet production requirements, resulting in low material utilization. The head mold fixture in this application moves synchronously with the head mold and does not need to span the mold. Therefore, the thickness can be set to less than 3 mm, improving material utilization.

[0030] 6. The main mold fixture is equipped with a compressed air channel and a water cooling channel. The compressed air channel is connected to the contour cooling cavity, and the water cooling channel is arranged in parallel with the compressed air channel. The compressed air channel is used to cool the areas of the plastic bottle that are not fully enclosed by the contour cooling cavity. The water cooling channel cools the clean air entering the compressed air channel of the main mold fixture, achieving cold air output and simultaneously reducing the temperature of the main mold fixture. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG1 is a schematic diagram of the first stage of the process of the present invention, showing the state of the tube embryo being discharged, and the air inlet channel introducing sterile clean air into the tube embryo;

[0032] Figure 2 is a left side view of Figure 1;

[0033] FIG3 is a schematic diagram of the second stage of the present invention, showing the initial state of the main mold clamp being closed, with the main mold clamp clamping and tightening the tube blank and moving downward;

[0034] FIG4 is a schematic diagram of the third stage of the present invention, showing that the mold, head mold fixture, main mold fixture and tube embryo have all reached the mold closing position, the second main mold is closed, the first main mold and head mold are in the mold opening state, the filling tube is filled, and the main mold fixture clamps the tube embryo and moves downward;

[0035] FIG5 is a schematic diagram of the fourth stage of the present invention, showing the first main mold in the closed state, the first main mold in the closed state, the head mold in the open state, the filling tube is filled, and the main mold clamp is clamping and tightening the tube blank and moving downward;

[0036] FIG6 is a schematic diagram of the fifth stage of the present invention, showing the head mold in a closed state, the head mold is closed, and the main mold clamp is clamping and tightening the tube blank and moving downward;

[0037] FIG7 is a schematic diagram of the sixth stage of the present invention, showing the state of the head mold clamp being closed, the head mold clamp being closed, and the main mold clamp holding and tightening the tube blank and moving downward;

[0038] FIG8 is a schematic diagram of the seventh stage of the present invention, showing the state where the mold reaches the mold opening position;

[0039] FIG9 is a schematic diagram of the eighth stage of the present invention, showing that the mold, head mold fixture and tube embryo have all reached the mold clamping position, the head mold fixture is opened and moves up with the mold to the mold clamping position, and the main mold fixture clamps and tightens the tube embryo and moves downward;

[0040] FIG10 is a schematic diagram of the ninth stage of the present invention, showing the second main mold in the closed state, the second main mold in the closed state, and the main mold fixture in the open state and moved upward;

[0041] FIG11 is a schematic diagram of the tenth stage of the present invention, showing the main mold fixture in the closed state, the first main mold and the head mold in the open state, the filling tube is filled, and the main mold fixture clamps the tube blank downward;

[0042] FIG12 is a schematic diagram of the head mold fixture and the main mold fixture of the present invention being respectively embedded in the head mold and the second main mold;

[0043] Figure 13 is a schematic diagram of the water cooling channel in the main mold fixture.

[0044] In the figure: 1. Extrusion device; 2. Filling tube; 3. Clamp; 4. Mold; 5. Collection tube; 6. Cooling device; 7. Monitoring device; 8. Product chain; 101. Tube embryo; 201. Air inlet channel; 202. Liquid inlet channel; 301. Head mold clamp; 302. Main mold clamp; 303. Second positioning and molding device; 304. Compressed air channel; 305. Water cooling channel; 401. Head mold; 402. First main mold; 403. First positioning and molding device; 404. Second main mold; 405. Mold closing position; 406. Mold opening position; 407. Temperature probe; 801. First bottle body; 802. Second bottle body; In Figure 1 and Figures 3-12: Arrow A indicates the movement direction of the tube embryo. DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with the embodiments:

[0046] Example 1

[0047] As shown in Figures 1 to 11, the multi-layer continuous molding process for plastic bottles according to the present invention includes the following steps:

[0048] (1) Discharging the tube blank 101: The extrusion device 1 extrude the hot melt tube blank 101, the filling tube 2 is inserted into the extrusion device 1, and the filling tube 2 extends into the hot melt tube blank 101; multiple filling tubes 2 can be arranged side by side, as shown in Figures 1 and 2;

[0049] The filling tube 2 is provided with a liquid inlet channel 202 and an air inlet channel 201. The liquid inlet channel 202 is used to fill the plastic bottle with liquid after the plastic bottle body is formed; the air inlet channel continuously introduces clean air into the hot melt tube blank 101, thereby keeping the hot melt tube blank 101 in an inflated state, ensuring that the hot melt tube blank 101 will not collapse and produce wrinkles on the surface of the formed plastic bottle.

[0050] (2) Initial sealing of the tube blank 101: The main mold fixture 302 closes the mold to seal the hot melt tube blank 101 and pulls the hot melt tube blank 101 downward; the fixture 3 includes the main mold fixture 302 and the head mold fixture 301. When performing the initial sealing of the tube blank 101, only the main mold fixture 302 closes the mold to seal the hot melt tube blank 101, and the head mold fixture 301 does not move, as shown in Figure 3;

[0051] (3) Bottle body forming and filling: After the hot melt tube blank 101 reaches the main mold closing position, the mold 4 is closed: the mold 4 includes a head mold 401, a first main mold 402, and a second main mold 404 that can be opened and closed independently. The head mold 401, the first main mold 402, and the second main mold 404 can be installed on a common track and move up and down synchronously. The vertical distance between the head mold 401, the first main mold 402, and the second main mold 404 remains unchanged, ensuring that a complete plastic bottle can be formed after the mold is closed; the head mold 401, the first main mold 402, and the second main mold 404 are independent of each other in terms of lateral movement, that is, the opening and closing of the head mold 401, the opening and closing of the first main mold 402, and the opening and closing of the second main mold 404 are independent of each other and do not interfere with each other;

[0052] A second body cavity is defined within the second main mold 404. A first body cavity and a second finish cavity are defined within the first main mold 402, sequentially from top to bottom. The second finish cavity corresponds to the second body cavity. The first finish cavity is defined within the head mold 401, corresponding to the first body cavity. Temperature probes 407 are provided on both the first and second main molds 402 and 404, communicating with the first and second body cavities, respectively. These probes are used to monitor the wall temperature of the plastic bottles before filling, enabling online control of the bottle wall temperature before filling, thereby preventing deterioration of heat-sensitive liquids.

[0053] The second main mold 404 is closed, and the second bottle body 802 is formed; the first main mold 402 and the head mold 401 are in the open state, and the filling tube 2 is filled with liquid medicine; after the second bottle body 802 is filled, the first main mold 402 is closed to seal the second bottle body 802 while the first bottle body 801 is formed; the head mold 401 is in the open state, and the filling tube 2 is filled with liquid medicine, as shown in Figures 4, 5, 10 and 11;

[0054] (4) Sealing the first bottle body 801: After filling is completed, the head mold 401 is closed and the mouth of the first bottle body 801 is sealed; as shown in FIG6;

[0055] (5) Sealing the tube blank 101: The head mold fixture 301 closes the mold and clamps the formed product chain 8; as shown in Figure 7;

[0056] (6) Product chain 8 molding: the mold 4, the main mold fixture 302 and the head mold fixture 301 move down together to the mold opening position 406. The mold 4 opens, and the head mold fixture 301 opens in sequence and moves up synchronously with the mold 4, returning to the mold closing position 405. The main mold fixture 302 continues to clamp the product chain 8 and moves down, stretching the parison to prevent it from shaking left and right due to the demoulding force; as shown in Figures 8 and 9;

[0057] (7) Positioning before mold closing: When the main mold fixture 302 holds the product chain 8 and moves down to match the mold closing position 405, step (3) is repeated. At the same time, the main mold fixture 302 opens the mold and moves up to the position corresponding to the previous product chain 8. The main mold fixture 302 closes the mold; as shown in Figures 10 and 11;

[0058] Repeat steps (4) to (7) to form a cycle to achieve continuous production of plastic bottles.

[0059] The head mold fixture 301 can be embedded in the head mold 401, and the main mold fixture 302 can be embedded in the second main mold 404. Plastic bottles vary in size. According to customer needs, a single device is required to adapt to the production of bottles of different sizes. Therefore, different molds need to be designed according to different bottle shapes, resulting in the inability to standardize mold production. Therefore, molds of uniform height are used. However, due to the different heights of the bottles, the cavity heights will also be different. As a result, cavities will appear in the head mold and the second main mold. If the head mold fixture is placed above the head mold and the main mold fixture is placed below the second main mold, after the head mold fixtures are closed, the tube blank corresponding to the head mold cavity will become waste, resulting in a waste of resources. The head mold fixture 301 can be embedded in the head mold 401, and the main mold fixture 302 can be embedded in the second main mold 404, avoiding resource waste, as shown in Figure 12.

[0060] The tube blank 101 is an oblong tube blank 101 or an elliptical tube blank 101. A plurality of filling tubes 2 are arranged in parallel in the tube blank 101.

[0061] During the bottle body forming, filling and bottle mouth sealing, the mold 4 continuously pulls the hot melt tube blank 101 downward.

[0062] The apparatus further includes a collection tube 5 and a monitoring device 7. As shown in FIG3 , the collection tube 5 is placed within the extrusion device 1 and extends through the extrusion device 1. The bottom end of the collection tube 5 is connected to the tube blank 101, and the top end of the collection tube 5 is connected to the monitoring device 7. The collection tube 5 collects the sterile gas within the tube blank 101 in real time and transfers it to the monitoring device 7, thereby achieving online control of the sterile environment within the tube blank 101. A cooling device 6 is also provided on the collection tube 5 near the monitoring device 7 to control the temperature of the collected sterile gas, preventing overheated sterile gas from damaging the monitoring device 7 or causing inaccurate monitoring data.

[0063] The head mold fixture 301 is placed above the head mold 401 and can be matched with the head mold 401; the main mold fixture 302 is placed below the second main mold 404 and can be matched with the second main mold 404.

[0064] When the hot melt tube blank 101 is sealed, the main mold fixture 302 is in a closed state, and the head mold fixture 301 is in an open state.

[0065] The main mold fixture 302 is provided with contoured cooling cavities. These provide secondary cooling for the thermoformed plastic bottles, ensuring thorough cooling of the product chain 8 and preventing stretching and deformation due to its own weight. The contoured cooling cavities on the main mold fixture 302 are arranged in at least two rows, but may be arranged in more rows, enabling multiple cooling of the bottles and thus achieving ultra-low temperature filling requirements.

[0066] A compressed air channel 304 and a water cooling channel 305 are provided in the main mold fixture 302 . The compressed air channel 304 is connected to the contour cooling cavity, and the water cooling channel 305 is provided corresponding to the compressed air channel 304 , as shown in FIG13 .

[0067] A first drive device is provided for the head mold fixture 301, and a second drive device is provided for the main mold fixture 302. The first and second drive devices are independently provided. The independent drive devices for the head mold fixture 301 and the main mold fixture 302 better accommodate their movement and allow for adjustment of their positions to accommodate the production of bottles of varying specifications.

[0068] The first main mold 402 and the second main mold 404 are both provided with a first positioning molding device 403, and the main mold fixture 302 is provided with a second positioning molding device 303 corresponding to the first positioning molding device 403. This ensures that when the main mold fixture 302 is closed, the positions of the two formed plastic bottles match.

[0069] The thickness of the head mold fixture 301 is 0.5, 2 or 3 mm.

[0070] The description of the direction and relative position relationship of the structure in the present invention, such as the description of front, back, left, right, up and down, does not constitute a limitation of the present invention and is only for the convenience of description.

Claims

1. A multi-layer continuous molding process for plastic bottles, characterized in that: The following steps are involved: (1) Discharging of the tube embryo (101): the extrusion device (1) extrude the hot melt tube embryo (101), the filling tube (2) is inserted into the extrusion device (1), and the filling tube (2) extends into the hot melt tube embryo (101); (2) Initial sealing of the tube embryo (101): the main mold fixture (302) closes the mold to seal the hot melt tube embryo (101), and tightens the hot melt tube embryo (101) to move downward; (3) Bottle body molding and filling: After the hot melt tube blank (101) reaches the main mold clamping position, the mold (4) is clamped: the mold (4) includes a head mold (401) that can be opened and closed independently, a first main mold (402) and a second main mold (404); the second main mold (404) is clamped, and the second bottle body (802) is molded; the first main mold (402) and the head mold (401) are in the open mold state, and the filling tube (2) is filled with liquid medicine; after the second bottle body (802) is filled, the first main mold (402) is clamped, so that the second bottle body (802) is sealed while the first bottle body (801) is molded; the head mold (401) is in the open mold state, and the filling tube (2) is filled with liquid medicine; (4) Sealing the first bottle body (801): After filling is completed, the head mold (401) is closed and the mouth of the first bottle body (801) is sealed; (5) Sealing the tube blank (101): The head mold fixture (301) closes the mold and clamps the formed product chain (8); (6) Molding of the product chain (8): the mold (4), the main mold fixture (302) and the head mold fixture (301) move downward together to the mold opening position (406), the mold (4) opens, and the head mold fixture (301) opens in sequence, and moves upward synchronously with the mold (4), and resets to the mold closing position (405); the main mold fixture (302) continues to clamp the product chain (8) and continues to move downward, and stretches the parison to prevent it from shaking left and right due to the influence of the demoulding force; (7) Positioning before mold closing: When the main mold fixture (302) holds the product chain (8) and moves down to match the mold closing position (405), step (3) is repeated, and at the same time, the main mold fixture (302) opens the mold and moves up to the position corresponding to the previous product chain (8), and the main mold fixture (302) closes the mold; Repeat steps (4) to (7) to form a cycle to achieve continuous production of plastic bottles.

2. The multi-layer continuous molding process for plastic bottles according to claim 1, characterized in that: A second bottle body cavity is provided in the second main mold (404), a first bottle body cavity and a second bottle mouth cavity are provided in sequence from top to bottom in the first main mold (402), the second bottle mouth cavity corresponds to the second bottle body cavity, a first bottle mouth cavity is provided in the head mold (401) corresponding to the first bottle body cavity, and temperature probes (407) are provided on both the first main mold (402) and the second main mold (404), and the temperature probes (407) are respectively connected to the first bottle body cavity and the second bottle body cavity.

3. The multi-layer continuous molding process for plastic bottles according to claim 2, characterized in that: The head mold fixture (301) can be embedded in the head mold (401), and the main mold fixture (302) can be embedded in the second main mold (404).

4. The multi-layer continuous molding process for plastic bottles according to claim 1, characterized in that: The bottle body is formed, filled and the bottle mouth is sealed, and the mold (4) continuously pulls the hot melt tube embryo (101) downward.

5. The multi-layer continuous molding process for plastic bottles according to claim 2, characterized in that: It also includes a collection tube (5) and a monitoring device (7). The collection tube (5) is placed in the extrusion device (1) and is arranged to pass through the extrusion device (1). The bottom end of the collection tube (5) is connected to the tube embryo (101), and the top end of the collection tube (5) is connected to the monitoring device (7).

6. The multi-layer continuous molding process for plastic bottles according to claim 2, characterized in that: When the hot melt tube blank (101) is sealed, the main mold fixture (302) is in a mold closing state, and the head mold fixture (301) is in a mold opening state.

7. The multi-layer continuous molding process for plastic bottles according to claim 6, characterized in that: A first driving device is provided corresponding to the head mold fixture (301), and a second driving device is provided corresponding to the main mold fixture (302), and the first driving device and the second driving device are provided independently of each other.

8. The multi-layer continuous molding process for plastic bottles according to claim 1, characterized in that: A contoured cooling cavity is provided on the main mold fixture (302).

9. The multi-layer continuous molding process for plastic bottles according to claim 8, characterized in that: A compressed air channel (304) and a water cooling channel (305) are provided in the main mold fixture (302); the compressed air channel (304) is communicated with the contoured cooling cavity; and the water cooling channel (305) is provided corresponding to the compressed air channel (304).

10. The multi-layer continuous molding process for plastic bottles according to claim 3, characterized in that: The thickness of the head mold fixture (301) is 0.5-3 mm.

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