Integrated forming device for roto-molding box

Abstract

This invention provides an integrated rotational molding device for boxes, belonging to the field of plastic mold production technology. The device includes an upper mold and a lower mold, with a mold cavity between them. A movable insert is slidably mounted on the upper mold, extending deep into the mold cavity and abutting against the inner wall of the lower mold. When the movable insert slides, it can also retract into the upper mold. A filling cavity is provided in the lower mold. Through the movable insert, molten material can be covered onto it. Before the material covering the insert has completely cooled and solidified, the movable insert is retracted, separating from the material covering it. At this point, the center of the material is hollow. Molten material is then added to the hollow portion through the filling structure. After complete cooling, a stable reinforcing column is formed, improving the stability of the box and preventing dents.

Description

Technical Field

[0001] This invention belongs to the field of plastic mold production technology, and specifically relates to an integrated rotational molding device for boxes. Background Technology

[0002] Rotational molding boxes are high-strength plastic containers manufactured using rotational molding technology. They have significant advantages such as robust structure, good sealing, corrosion resistance, and customizability. They are widely used in many fields such as aviation logistics, medical equipment, and fire rescue. The rotational molding process involves evenly distributing plastic powder on the surface of a heated mold. Through the rotation and heating of the mold, the plastic melts and adheres tightly to the mold cavity. Finally, it cools and solidifies to obtain a hollow product.

[0003] Chinese patent CN119682093B discloses a rotational molding apparatus for producing parts for children's playground slides. The apparatus includes a mold placement mechanism and heat dissipation mechanisms located on the left and right sides of the mold placement mechanism. The mold placement mechanism includes a swing arm, a mold mounting frame that rotates with the swing arm, and a first drive motor that drives the swing arm to rotate. In this rotational molding apparatus and method for producing parts for children's playground slides, when the second drive motor is started, the reciprocating screw rotates, causing the moving part to reciprocate within the swing frame. Simultaneously, through the transmission part, the angle of the entire swing frame changes, thereby increasing the coverage area of ​​the heat dissipation fan inside the moving part, thus optimizing airflow distribution and improving the uniformity of mold heat dissipation.

[0004] When producing components with large flat surfaces, such as housings, the large flat surfaces shrink after cooling, creating a negative pressure inside the housing. The external atmospheric pressure then flattens the flat surfaces, causing them to cave inward. Summary of the Invention

[0005] The purpose of this invention is to provide an integrated molding device for rotational molding boxes, which aims to solve the problem that dents are easily caused when parts with large flat surfaces are produced by rotational molding in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an integrated rotational molding device for a box, comprising: an upper mold and a lower mold, with a mold cavity between the upper mold and the lower mold, a movable insert slidably disposed on the upper mold, the movable insert being able to penetrate deep into the interior of the mold cavity and abut against the inner wall of the lower mold, and being able to retract into the interior of the upper mold when the movable insert slides, a filling cavity being disposed in the lower mold, a piston being slidably disposed in the filling cavity, an injection port being disposed at one end of the filling cavity near the mold cavity, and a first elastic element being disposed at the end of the piston away from the injection port, when the movable insert is located inside the mold cavity, the movable insert pushes the piston to move away from the injection port and compresses and stores energy in the first elastic element, and when the first elastic element releases energy, it can push the molten material inside the filling cavity downwards towards the movable insert.

[0007] A further technical solution of the present invention is that the movable insert includes a sliding column, which is slidably disposed on the upper mold and extends into the interior of the mold cavity. A push column is slidably disposed inside the sliding column along its axis. One end of the push column extends into the interior of the plasticizing cavity and can abut against the piston. A second sliding cavity is also provided inside the sliding column. A second limiting ring is fixed on the push column and slides inside the second sliding cavity. A second elastic element is provided inside the second sliding cavity to push the second limiting ring to move toward the injection port.

[0008] A further technical solution of the present invention is that a protrusion is provided at one end of the piston near the injection port. When the piston moves to the top, the protrusion can seal the injection port and make the protrusion flush with the inner wall of the lower mold.

[0009] A further technical solution of the present invention is that the upper mold has a first sliding cavity, and a first limiting ring is provided on the sliding column to slide inside the first sliding cavity. When the sliding column slides away from the injection port, the first limiting ring can abut against one end of the first sliding cavity. At this time, the end face of the sliding column near the injection port is on the same plane as the lower plane of the upper mold.

[0010] A further technical solution of the present invention is that a groove is provided in the upper mold, and a lifting frame is provided in the groove. The push columns located at the bottom of the lower mold are detachably connected to the bottom of the lifting frame, so that the lifting frame can directly drive the push columns to move up and down. A sliding groove is provided on the side of the lifting frame. The sliding groove has a vertical section and an inclined section. A slider is provided on the push column located on the side wall of the lower mold. The slider can slide inside the sliding groove. When the lifting frame moves upward, the inclined section can cause multiple sliders to drive the push columns to move away from the injection port. An upwardly extending lead screw is provided on the lifting frame. A crossbeam is provided at the opening of the groove in the upper mold. The lead screw passes through the crossbeam and is fixed to the crossbeam by screws.

[0011] A further technical solution of the present invention is that the lower mold is provided with a first channel and a second channel. The first channel connects the plasticizing structures located at the bottom of the lower mold in series, so that the plasticizing cavities located at the bottom of the lower mold are interconnected through the first channel. The second channel can connect multiple plasticizing structures located on the side wall of the lower mold in series, so that the plasticizing cavities located on the side wall of the lower mold are interconnected through the second channel. A perforation is provided between the first channel and the second channel, so that the first channel and the second channel are interconnected. The lower mold is also provided with a feed hole and a vent hole. The feed hole is used to inject molten raw material into the plasticizing cavity through the first channel and the second channel. The vent hole is used to discharge the gas in the plasticizing cavity. A valve is provided at the vent hole.

[0012] A further technical solution of the present invention is that the lower mold is provided with an insulation sleeve for keeping the plastic filling cavity warm.

[0013] A further technical solution of the present invention is that an exhaust port is provided at the end of the plasticizing cavity away from the injection port.

[0014] A further technical solution of the present invention is that the diameter of the injection port is smaller than the diameter of the sliding column.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] 1. By setting up movable inserts, molten raw materials can be covered on the movable inserts. The raw materials covering the movable inserts have not yet completely cooled and solidified. At this time, the movable inserts are retracted and separated from the raw materials covering them. At this time, the middle of the raw materials is in a hollow state. Molten raw materials are filled into the hollow part through the plastic filling structure. After it is completely cooled, a stable reinforcing column can be formed, which improves the stability of the box and avoids the problem of the box sinking.

[0017] 2. The lifting frame allows for simultaneous and synchronous control of the movement of multiple movable inserts, which can increase the number of reinforcing columns inside the enclosure, thereby increasing the strength of the enclosure. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0019] Figure 1 This is a schematic diagram of a specific embodiment of the present invention;

[0020] Figure 2 This is an isometric sectional view of a specific embodiment of the present invention;

[0021] Figure 3 for Figure 2 Enlarged structural diagram at point A;

[0022] Figure 4 This is a schematic diagram of the lifting frame in a specific embodiment of the present invention;

[0023] Figure 5 for Figure 4 Enlarged structural diagram at point B;

[0024] Figure 6 This is a schematic diagram of the structure of the first channel in a specific embodiment of the present invention;

[0025] Figure 7 This is a schematic diagram of the structure of the second channel in a specific embodiment of the present invention.

[0026] In the diagram: 1. Upper mold; 11. First sliding cavity; 12. Groove; 13. Crossbeam; 2. Lower mold; 21. First channel; 22. Second channel; 23. Through hole; 24. Feed hole; 25. Vent hole; 3. Movable insert; 31. Sliding column; 311. First limiting ring; 312. Second sliding cavity; 4. Plastic repair structure; 41. Plastic repair cavity; 42. Piston; 421. Protrusion; 43. Injection port; 44. First elastic element; 45. Vent hole; 46. Push column; 461. Second limiting ring; 462. Slider; 47. Second elastic element; 5. Lifting frame; 51. Slide groove; 511. Vertical section; 512. Inclined section; 52. Lead screw; 6. Insulation sleeve. Detailed Implementation

[0027] 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.

[0028] Please see Figures 1-7 The present invention provides the following technical solution: an integrated molding device for rotational molding boxes, including a mold body, the mold body including an upper mold 1 and a lower mold 2, and a movable insert 3 and a plastic repair structure 4 are also installed on the mold body.

[0029] The mold body is mounted on the swing arm of the rotational molding machine (not shown in the figure), so that the rotational molding machine can drive the mold body to revolve and rotate. The upper mold 1 and the lower mold 2 are connected by bolts or clips, forming a mold cavity between them. Raw material is added into the mold cavity, and the mold body is sent into the heating furnace. The rotational molding machine drives the mold body to revolve and rotate, so that the molten raw material covers the inside of the mold cavity to form a box.

[0030] The movable insert 3 is installed on the upper mold 1, extending deep into the mold cavity and abutting against the cavity wall of the lower mold 2. The plasticizing structure 4 is installed on the lower mold 2 and corresponds to the movable insert 3. When the mold body is cooled, the raw material covering the movable insert 3 has not yet completely cooled and solidified. At this time, the movable insert 3 is retracted and separated from the raw material covering it. At this time, the middle of the raw material is hollow. Molten raw material is added to the hollow part through the plasticizing structure 4. After it is completely cooled, a stable reinforcing column can be formed to improve the stability of the box and avoid the problem of the box sinking.

[0031] Please see Figure 2The lower mold 2 has a concave cross section, and the upper mold 1 has a protrusion located in the concave part of the lower mold 2. There is a gap between the concave part of the lower mold 2 and the protrusion of the upper mold 1 for forming the box body. Both the upper mold 1 and the lower mold 2 are provided with flanges, which can be used to fix the two with bolts or clips.

[0032] Please see Figure 3 The movable insert 3 includes a sliding column 31, which is slidably disposed on the upper mold 1 and extends into the interior of the mold cavity. One end of the sliding column 31 located inside the mold cavity abuts against the inner wall of the lower mold 2, so that the sliding column 31 forms a column inside the mold cavity. When the mold body rotates, the molten material will cover the outer surface of the sliding column 31, forming a hollow column.

[0033] Please see Figure 3 The molding structure 4 can replenish the material in the empty space left after the slide column 31 moves out. The molding structure 4 includes a molding cavity 41 located in the lower mold 2. Molten material is inside the molding cavity 41. A piston 42 is installed inside the molding cavity 41 and slides along its length. The piston 42 is sealed to the molding cavity 41. An injection port 43 is provided at one end of the molding cavity 41 near the mold cavity. The diameter of the injection port 43 is smaller than the diameter of the slide column 31, so that the molten material can be accurately squeezed into the hollow column that is about to solidify. At the same time, the slide column 31 can inject the material. The injection port 43 is sealed. A first elastic element 44 is provided at the end of the piston 42 away from the injection port 43. The first elastic element 44 can push the piston 42 to move towards the injection port 43. In use, after adding molten material to the end of the molding cavity 41 located near the injection port 43 of the piston 42, when the sliding column 31 is pulled out from the hollow column that is about to solidify, the piston 42 is pushed towards the injection port 43 under the action of the first elastic element 44, so that the molten material inside the molding cavity 41 can be squeezed into the hollow column that is about to solidify through the injection port 43.

[0034] The end of the molding cavity 41 away from the injection port is provided with an exhaust port 45. The exhaust port 45 can prevent the movement of the piston 42 from causing negative or positive pressure inside the molding cavity 41, thus avoiding the situation where the piston 42 has difficulty sliding inside the molding cavity 41. The end of the piston 42 near the injection port 43 is provided with a protrusion 421. The diameter of the protrusion 421 is the same as the diameter of the injection port 43, and the height of the protrusion 421 is the same as the depth of the injection port 43. When the piston 42 moves to the top, the protrusion 421 can seal the injection port 43. The protrusion 421 is flush with the inner wall of the lower mold 2, thus making the surface of the box smoother.

[0035] The upper mold 1 has a first sliding cavity 11 inside. The sliding column 31 is provided with a first limiting ring 311 that slides inside the first sliding cavity 11. When the sliding column 31 slides away from the injection port 43, the first limiting ring 311 can abut against the top of the first sliding cavity 11. At this time, the end face of the sliding column 31 near the injection port 43 is on the same plane as the lower plane of the upper mold 1, which makes the overall surface of the box smoother and reduces the additional processing steps of the box in the later stage.

[0036] A pusher 46 is slidably disposed inside the slide column 31 along its axis. The pusher 46 is coaxially disposed with the slide column 31 and passes through both ends of the slide column 31. One end of the pusher 46 extends into the interior of the molding cavity 41 and abuts against the protrusion 421. A second sliding cavity 312 is also disposed inside the slide column 31. A second limiting ring 461 that slides inside the second sliding cavity 312 is fixed on the pusher 46. A second elastic element 47, which is a compression spring, is disposed inside the second sliding cavity 312 to push the second limiting ring 461 toward the injection port 43. One end of the second elastic element 47 is fixed to the inner wall of the second sliding cavity 312, and the other end abuts against the second limiting ring 461. When the pusher 46 moves away from the injection port 43, the slide column 31 and the piston 42 move synchronously under the action of the first elastic element 44 and the second elastic element 47. The sliding column 31 moves away from the injection port 43, causing it to detach from the hollow cylinder that is about to solidify. The piston 42 moves towards the injection port 43, squeezing the molten material inside the molding cavity 41 into the hollow cylinder that is about to solidify. When the sliding column 31 is completely detached from the hollow cylinder and the molten material inside the molding cavity 41 is completely squeezed into the hollow cylinder that is about to solidify, the sliding column 31 is stopped by the first limiting ring 311, while the push column 46 continues to move and compresses the second elastic element 47 with the second limiting ring 461, causing the push column 46 to completely retract into the interior of the sliding column 31. The push column 46 is flush with the first end of the sliding column 31 near the injection port 43, thus preventing the solidified reinforcing column from being hollow, which would prevent the box from being unable to be sealed.

[0037] Please see Figure 2 , Figure 4 and Figure 5Since the four sides of the box body may be recessed, movable inserts 3 and plastic repair structures 4 are provided on the four side walls of the mold cavity. A groove 12 is provided in the upper mold 1, with the opening of the groove 12 facing upward. A lifting frame 5 is provided inside the groove 12. The bottom of the lifting frame 5 can be connected to the push column 46 installed on the horizontal surface of the mold cavity. The push column 46 and the lifting frame 5 are detachably connected by threads, so that when the lifting frame 5 moves upward, it can simultaneously drive the push column 46 to move upward. A sliding groove 51 is provided on the side of the lifting frame 5. The sliding groove 51 has a vertical section 511 and an inclined section 512. The vertical section 511 is located above the inclined section 512, and the inclined section 512 gradually moves away from the top to the bottom. A slider 462 is provided at one end of the pusher 46 near the lifting frame 5, which slides inside the slide groove 51. When the lifting frame 5 moves upward, the slider 462 slides inside the slide groove 51. Through the setting of the inclined section 512, the inclined surface of the inclined section 512 synchronously pushes multiple sliders 462 to move away from the injection port 43, and drives multiple synchronous pushers 46 to move. The multiple pushers 46 synchronously drive the slider 31 to move, retracting the part of the slider 31 located inside the mold cavity into the upper mold 1. This allows multiple pistons 42 to synchronously squeeze the molten material into the solidified hollow column, achieving the consistency of movement of multiple movable inserts 3 and the plasticizing structure 4. An upwardly extending lead screw 52 is provided on the lifting frame 5. A crossbeam 13 is provided at the opening of the groove 12 in the upper mold 1. The lead screw 52 passes through the crossbeam 13 and is fixed to the crossbeam 13 by screws to fix the position of the lifting frame 5.

[0038] Please see Figure 6 and Figure 7 The lower mold 2 has a first channel 21 and a second channel 22. The first channel 21 connects the plasticizing structures 4 located at the bottom of the lower mold 2 in series, making the interiors of multiple plasticizing cavities 41 interconnected. The second channel 22 connects the multiple plasticizing structures 4 located on the side wall of the lower mold 2 in series, making the interiors of multiple plasticizing cavities 41 interconnected. A through hole 23 is provided between the first channel 21 and the second channel 22, allowing the first channel 21 and the second channel 22 to communicate with each other. The lower mold 2 has a feed hole 24 and a discharge hole. The vent 25 and feed port 24 are connected to an external pressure device to feed molten raw materials into the molding cavity 41 through the first channel 21 and the second channel 22. A valve (not shown in the figure) is provided at the vent 25. When injecting molten raw materials into the molding cavity 41, the valve is opened to release the gas in the molding cavity 41, so as to avoid positive pressure in the molding cavity 41, which would make it difficult for the molten raw materials to enter the interior of the molding cavity 41. When the molding cavity 41 is filled with molten raw materials, the valve is closed to prevent the molten raw materials from being discharged from the vent 25.

[0039] The lower mold 2 is provided with a heat insulation sleeve 6 at the plasticizing structure 4. The heat insulation sleeve 6 is inserted into the interior of the lower mold 2 and covered on the outside of the plasticizing structure 4. It is used to keep the material in the plasticizing cavity 41 warm, without affecting the cooling of the material inside the mold cavity.

[0040] In use, the upper mold 1 and lower mold 2 are closed, and the slide column 31 is inserted into the mold cavity. Then, the rotational molding machine drives the mold body to rotate and revolve, adhering the molten material to the inner wall of the mold cavity and the slide column 31. After that, the mold body is removed from the heating furnace. At this time, molten material is added into the plasticizing cavity 41 through the first channel 21 and the second channel 22. The mold body is then cooled. At this time, due to the setting of the heat insulation sleeve 6, the material in the plasticizing cavity 41 can slow down the cooling rate of the material in the plasticizing cavity 41, ensuring the fluidity of the molten material in the plasticizing cavity 41. After a certain cooling time, the material adhering to the slide column 31 is not completely cooled. At this time, multiple slide columns 31 are pulled out from the material, and the plasticizing structure 4 replenishes the part of the slide column 31 that has been removed with molten material. Finally, wait for the box to cool completely before demolding.

Claims

1. A rotational molding device for an integrated box, comprising: The upper mold (1) and the lower mold (2) have a mold cavity between them. The upper mold (1) is characterized by a movable insert (3) slidably disposed on it. The movable insert (3) can penetrate deep into the mold cavity and abut against the inner wall of the lower mold (2). When the movable insert (3) slides, it can also retract into the upper mold (1). A molding cavity (41) is provided inside the lower mold (2). A piston (42) is slidably disposed inside the molding cavity (41). The molding cavity (41) is close to... An injection port (43) is provided at one end of the mold cavity, and a first elastic element (44) is provided at the end of the piston (42) away from the injection port (43). When the movable insert (3) is located inside the mold cavity, the movable insert (3) pushes the piston (42) to move away from the injection port (43) and compresses and stores energy in the first elastic element (44). When the first elastic element (44) releases energy, it can push the molten material inside the plasticizing cavity (41) to the bottom of the movable insert (3). The movable insert (3) includes a slide column (31), which is slidably disposed on the upper mold (1) and extends into the interior of the mold cavity. A push column (46) is slidably disposed inside the slide column (31) along its axis. One end of the push column (46) extends into the interior of the plasticizing cavity (41) and can abut against the piston (42). A second sliding cavity (312) is also disposed inside the slide column (31). A second limiting ring (461) is fixed on the push column (46) and slides inside the second sliding cavity (312). A second elastic element (47) is disposed inside the second sliding cavity (312) to push the second limiting ring (461) to move toward the injection port (43).

2. The rotational molding box integrated molding device according to claim 1, characterized in that: The piston (42) has a protrusion (421) at one end near the injection port (43). When the piston (42) moves to the top, the protrusion (421) can seal the injection port (43) and make the protrusion (421) flush with the inner wall of the lower mold (2).

3. The rotational molding box integrated molding device according to claim 1, characterized in that: The upper mold (1) has a first sliding cavity (11) inside. The sliding column (31) is provided with a first limiting ring (311) that slides inside the first sliding cavity (11). When the sliding column (31) slides away from the injection port (43), the first limiting ring (311) can abut against one end of the first sliding cavity (11). At this time, the end face of the sliding column (31) near the injection port (43) is on the same plane as the lower plane of the upper mold (1).

4. The rotational molding box integrated molding device according to claim 1, characterized in that: The upper mold (1) has a groove (12) inside, and a lifting frame (5) is installed in the groove (12). The push column (46) located at the bottom of the lower mold (2) is detachably connected to the bottom of the lifting frame (5), so that the lifting frame (5) can directly drive the push column (46) to move up and down. A sliding groove (51) is provided on the side of the lifting frame (5). The sliding groove (51) has a vertical section (511) and an inclined section (512). A slider (462) is provided on the push column (46) located on the side wall of the lower mold (2). The block (462) can slide inside the groove (51). When the lifting frame (5) moves upward, the inclined section (512) enables multiple sliders (462) to drive the push column (46) to move away from the injection port (43). The lifting frame (5) is provided with an upwardly extending lead screw (52). The upper mold (1) is provided with a crossbeam (13) at the opening of the groove (12). The lead screw (52) passes through the crossbeam (13) and is fixed to the crossbeam (13) by screws.

5. The rotational molding box integrated molding device according to claim 1, characterized in that: The lower mold (2) is provided with a first channel (21) and a second channel (22). The first channel (21) connects the plasticizing structures (4) located at the bottom of the lower mold (2) in series, so that the plasticizing cavities (41) located at the bottom of the lower mold (2) are interconnected through the first channel (21). The second channel (22) can connect multiple plasticizing structures (4) located on the side wall of the lower mold (2) in series, so that the plasticizing cavities (41) located on the side wall of the lower mold (2) are interconnected through the second channel (22). A perforation (23) is provided between the first channel (21) and the second channel (22) so that the first channel (21) and the second channel (22) are connected to each other. The lower mold (2) is also provided with a feed hole (24) and an exhaust hole (25). The feed hole (24) is used to inject molten raw material into the plasticizing cavity (41) through the first channel (21) and the second channel (22). The exhaust hole (25) is used to discharge the gas in the plasticizing cavity (41). A valve is provided at the exhaust hole (25).

6. The rotational molding box integrated molding device according to claim 5, characterized in that: The lower mold (2) is provided with an insulation sleeve (6) to keep the plastic filling cavity (41) warm.

7. The rotational molding box integrated molding device according to claim 1, characterized in that: The end of the plasticizing cavity (41) away from the injection port (43) is provided with an exhaust port (45).

8. The rotational molding box integrated molding device according to claim 1, characterized in that: The diameter of the injection port (43) is smaller than the diameter of the slide (31).

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