Forming equipment and forming process for thin-wall plastic box

Abstract

The invention relates to forming equipment and a forming process of a thin-wall plastic box, and relates to the technical field of injection molding device.The forming equipment comprises a base, an injection molding machine, a fixed seat, a fixed mold and a movable mold, a pressing rod is fixed to the side, facing the movable mold, of the fixed seat, the movable mold is provided with an air cavity for sliding connection of the pressing rod, and the inner wall of the cavity is provided with a movable hole communicating with the air cavity; a valve block is arranged in the movable hole, the valve block is in threaded connection with the internal thread section, the valve block is connected with a control block, a spiral sliding groove is formed in the side wall of the control block, and the sliding groove is used for being in sliding fit with the sliding block. Air injection is started only after the valve block is recessed in the cavity, and the problem that the thin-wall plastic box is damaged due to the fact that the air valve piece is ejected out of the surface of the cavity is solved; the valve block moves inwards in a concave mode while rotating, the end face of the valve block can be rapidly separated from a plastic product, and the problems of deformation or wire drawing and the like caused by plastic pulling are avoided. The mechanism can press air to blow and demould, and the blowing operation can be automatically carried out without depending on electric control or externally connecting compressed air.

Description

Technical Field

[0001] The present application relates to the technical field of injection molding equipment, and in particular to a molding equipment and molding process for a thin-walled plastic box. Background Art

[0002] Thin-walled plastic boxes are common disposable containers in life and are widely used in the food packaging industry. They can be used to hold biscuits, snacks and other foods. Thin-walled plastic boxes are produced using injection molding equipment, which includes injection machines, molds, etc. In order to reduce the damage of the ejector to the thin-walled plastic boxes during the demoulding process, there are structures on the market that use compressed air to assist demoulding.

[0003] The invention patent application with the publication number CN103817883A discloses a compressed air demoulding device for thin-walled deep-cavity molds, including an air source, an air channel, an air tip, an air port, an air nozzle, a quick connector, a static mold, and a dynamic mold. The air channel is a multi-channel and independent air path system arranged inside the static mold and the dynamic mold; its plug is opened by pneumatic operation, and the compressed air outlet component that automatically resets the seal when there is no air pressure; the air nozzle is an air jet hole that is connected to the independent air channel and is arranged on the parting surface of the dynamic mold. After the mold is opened, the electromagnetic valve of the dynamic mold air tip is opened, and the compressed air blows against the plug of the air tip opened on the top of the dynamic mold to push the plastic product forward to separate. At the same time, the compressed air enters between the side wall of the core and the plastic product through the air port, and forms an air cushion layer to produce a lubricating effect to assist the plastic product to separate from the core. After a delay of several seconds, the electromagnetic valve of the dynamic mold air nozzle is opened, and the compressed air blows forward through the air nozzle arranged on the parting surface of the dynamic mold, and the strong airflow pushes the plastic product to fall off.

[0004] With respect to the above-mentioned related technologies, the inventor believes that when the air tip at the cavity is opened, it must be ejected from the inner wall of the cavity. This process occurs before blowing. However, the thin-walled plastic box that has just been molded has not yet cooled, has a low hardness, and has a thin wall thickness. The quickly ejected air tip can easily damage the thin-walled plastic box. Summary of the invention

[0005] The present application provides a molding device and a molding process for a thin-walled plastic box, in which the opening of an air valve component at a mold cavity will not push out of the mold cavity surface, thereby avoiding damage to the thin-walled plastic box.

[0006] The present application provides a thin-wall plastic box forming device, which adopts the following technical solution: A molding device for a thin-walled plastic box comprises a base, an injection machine, a fixed seat, a fixed mold and a movable mold, wherein the fixed mold is fixedly connected to the output end of the injection machine, the movable mold is slidably arranged on the base, a cavity is arranged on the side of the movable mold and the fixed mold facing each other, a pressure rod is fixed on the fixed seat facing the movable mold, an air cavity for the pressure rod to slide and connect is provided on the movable mold, a sealing ring is provided between the pressure rod and the inner wall of the air cavity, an active hole communicating with the air cavity is provided on the inner wall of the cavity, a valve block is provided in the active hole, an internal thread section is provided on the inner wall of the active hole close to the cavity, the outer wall of the valve block is threadedly connected to the internal thread section, the valve block is connected to a control block, the side wall of the control block is provided with a spiral slide groove, a connecting rod is fixed to the end of the pressure rod, a slider is fixed to the end of the connecting rod, and the slide groove is used for the sliding cooperation of the slider.

[0007] By adopting the above technical solution, when the pressure rod moves toward the control block, the air in the air cavity is compressed; the slider enters the slide groove, and then the slider slides along the spiral slide groove. Since the pressure rod cannot rotate, the control block rotates counterclockwise, thereby driving the valve block to rotate counterclockwise, thereby twisting the valve block away from the cavity, causing the valve block to rotate and concave in the cavity. The valve block starts to spray air after it is concave in the cavity, avoiding the problem of the air valve component pushing out of the cavity surface and damaging the thin-walled plastic box.

[0008] Optionally, the pressure rod is arranged to pass through the fixing seat, the interior of the pressure rod is hollow and both ends are connected, and a one-way valve is fixed to one end of the pressure rod away from the connecting rod.

[0009] By adopting the above technical solution, the one-way conduction direction of the one-way valve is from the outer side of the pressure rod end toward the inside of the pressure rod, so that the outside air can enter the channel in the pressure rod through the one-way valve and then enter the air cavity, while the air in the air cavity cannot flow reversely through the one-way valve.

[0010] Optionally, an inner wall of the movable hole is provided with an inclined groove, one end of the inclined groove is arranged close to the cavity, and the other end of the inclined groove is connected to the internal thread section. The valve block is penetrated by a vent hole 1, and the vent hole 1 is used to connect to the inclined groove. When the valve block is tightened on the internal thread section, the vent hole 1 is staggered from the inclined groove.

[0011] By adopting the above technical solution, when the valve block is tightened on the internal thread section, the vent hole 1 and the inclined groove are staggered to prevent the air in the air cavity from entering the movable hole. When the valve block is loosened outside the internal thread section, the vent hole 1 and the inclined groove are gradually connected to each other as the valve block rotates, and the valve block moves away from the cavity, and the inclined groove connects the vent hole 1 with the cavity, thereby starting the air injection.

[0012] Optionally, a plurality of guide rods are fixed on the end face of the valve block facing the control block, a limit plate is fixed on the guide rods, the guide rods are slidably connected to the control block, a limit groove for the limit plate to slide is provided in the control block, and springs are provided on both sides of the limit plate.

[0013] By adopting the above technical solution, during the process of the control block driving the valve block to rotate, the valve block generates axial displacement, so the distance between the control block and the valve block will change. The valve block is slidably connected to the control block through the guide rod, so that the mechanism can operate normally. During the relative sliding process of the control block and the valve block, the spring adaptively expands and contracts.

[0014] Optionally, the control block is provided with a second vent hole, and the end of the second vent hole is opposite to the first vent hole.

[0015] By adopting the above technical solution, the second vent hole is connected between the air cavity and the vent hole, so that the gas flows smoothly.

[0016] Optionally, a sealing gasket is fixed on the end surface of the internal thread section close to the movable hole, the sealing gasket is annular, and an avoidance opening is opened on the inner ring wall of the sealing gasket, and the position of the avoidance opening corresponds to the inclined groove.

[0017] By adopting the above technical solution, when the valve block is tightened on the internal thread section, the port of the vent hole 1 is pressed against the surface of the sealing gasket, thereby improving the sealing effect and avoiding air leakage.

[0018] Optionally, at least two inclined grooves are provided along the circumference of the movable hole.

[0019] By adopting the above technical solution, the ventilation volume and the uniformity of the jet are improved.

[0020] Optionally, at least two connecting rods are provided along the circumference of the pressure rod, and at least two sliding grooves are provided along the circumference of the control block.

[0021] By adopting the above technical solution, the force is evenly distributed and the reliability of the slider drive control block is improved.

[0022] Optionally, an oil cylinder is fixed on the fixed seat, and an output end of the oil cylinder is fixed to the movable mold.

[0023] By adopting the above technical solution, the movable mold is driven to move by the extension and retraction of the oil cylinder, thereby realizing the opening and closing of the mold.

[0024] In a second aspect, the present application provides a molding process for a thin-walled plastic box, which adopts the following technical solution: A thin-walled plastic box forming process, using the above-mentioned thin-walled plastic box forming device, comprises the following steps: Step S1: mold closing, as the movable mold approaches the fixed mold, the pressure rod gradually moves away from the air cavity, so that the air pressure in the air cavity decreases, and air is introduced into the air cavity through the one-way valve; Step S2: After the mold is closed, the injection machine injects liquid plastic into the cavity; Step S3: After the plastic solidifies, the mold is opened, and as the movable mold moves away from the fixed mold, the pressure rod moves deep into the air cavity, increasing the air pressure in the air cavity; Step S4: When the slider slides into the slide groove, the control block rotates through the spiral slide groove, which in turn drives the valve block to rotate. The valve block moves away from the cavity through the threaded connection with the internal thread section, thereby opening the movable hole, and the compressed gas in the air cavity is ejected from the movable hole to demold the product.

[0025] By adopting the above technical solution, the problem of the air valve component ejecting from the cavity and damaging the thin-walled plastic box is avoided, and the mechanism itself can compress the air for blowing and demoulding. The blowing operation can be automatic, independent of electronic control, and does not require external compressed air.

[0026] In summary, the present application includes at least one of the following beneficial technical effects: 1. The air jet starts after the valve block is recessed into the cavity, which avoids the problem of the air valve component pushing out of the cavity surface and damaging the thin-walled plastic box; 2. The valve block rotates and moves inwards, and the end face of the valve block can be quickly separated from the plastic product to avoid deformation or drawing caused by pulling the plastic; 3. The mechanism itself can compress the air for blowing and demoulding. The blowing operation can be automatic, independent of electronic control and without external compressed air. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a three-dimensional diagram of a thin-wall plastic box forming device of an embodiment; Figure 2 is a cross-sectional view of a movable mold of an embodiment; Figure 3 yes Figure 2 A magnified image of point A; Figure 4 The three-dimensional structure of the pressure rod, control block and valve block of the embodiment Figure 1 ; Figure 5 The three-dimensional structure of the pressure rod, control block and valve block of the embodiment Figure 2 ; Figure 6 is a schematic diagram of an embodiment.

[0028] Explanation of the reference numerals in the accompanying drawings: 1. base; 11. injection molding machine; 12. fixed seat; 13. fixed mold; 2. movable mold; 14. oil cylinder; 21. cavity; 3. pressure rod; 22. air cavity; 31. sealing ring; 32. one-way valve; 23. movable hole; 4. valve block; 24. internal thread section; 41. control block; 42. slide groove; 33. connecting rod; 34. slider; 43. guide rod; 44. limit plate; 45. limit groove; 46. spring; 25. inclined groove; 47. vent hole 1; 48. vent hole 2; 5. sealing gasket. DETAILED DESCRIPTION

[0029] The present application is further described in detail below in conjunction with the accompanying drawings.

[0030] Example

[0031] Reference Figure 1 This embodiment discloses a thin-wall plastic box molding device, including a base 1, an injection machine 11, a fixed seat 12, a fixed mold 13 and a movable mold 2. The injection machine 11 and the fixed seat 12 are respectively fixed at two ends of the base 1. The fixed mold 13 is fixedly connected to the output end of the injection machine 11, and liquid plastic is injected between the fixed mold 13 and the movable mold 2 through the injection machine 11. The movable mold 2 is slidably arranged on the base 1, and the movable mold 2 is in sliding contact with the fixed seat 12. The fixed seat 12 is fixed with a cylinder 14, and the number of the cylinders 14 can be several. The output end of the cylinder 14 is fixed to the movable mold 2, and the movable mold 2 is driven to move by the extension and contraction of the cylinder 14, thereby realizing the opening and closing of the mold.

[0032] Reference Figure 2 The movable mold 2 and the fixed mold 13 are provided with a cavity 21 on the side facing each other, and a pressure rod 3 is fixed on the fixed seat 12 facing the movable mold 2. The movable mold 2 is provided with an air cavity 22 for the pressure rod 3 to slide and connect. A sealing ring 31 is provided between the pressure rod 3 and the inner wall of the air cavity 22. The sealing ring 31 is used to establish a sliding seal between the pressure rod 3 and the air cavity 22 to prevent air leakage. The pressure rod 3 is arranged through the fixed seat 12. The interior of the pressure rod 3 is hollow and both ends are connected. A one-way valve 32 is fixed on the end of the pressure rod 3 away from the connecting rod 33. The one-way conduction direction of the one-way valve 32 is from the outer side of the end of the pressure rod 3 to the inside of the pressure rod 3, so that the outside air can enter the channel in the pressure rod 3 through the one-way valve 32, and then enter the air cavity 22, while the air in the air cavity 22 cannot flow in the reverse direction through the one-way valve 32.

[0033] Reference Figure 3 and Figure 4The inner wall of the cavity 21 is provided with a movable hole 23 connected to the air cavity 22, and a valve block 4 is arranged in the movable hole 23. An internal thread section 24 is provided on the inner wall of the movable hole 23 close to the cavity 21. The outer wall of the valve block 4 is threadedly connected to the internal thread section 24. The valve block 4 is connected to a control block 41. The control block 41 is located on the side of the valve block 4 facing the pressure rod 3. A spiral groove 42 is provided on the side wall of the control block 41. A connecting rod 33 is fixed to the end of the pressure rod 3 facing the control block 41. A slider 34 is fixed to the end of the connecting rod 33. The slide groove 42 is used for sliding cooperation with the slider 34.

[0034] Reference Figures 3 to 5 The shape of the slider 34 is hemispherical, which improves the reliability of the slider 34 entering the end of the slide groove 42 and improves the smoothness of the slider 34 sliding with the slide groove 42. The connecting rod 33 is provided with at least two along the circumference of the pressure rod 3, and the slide groove 42 is provided with at least two along the circumference of the control block 41, so that the force is evenly applied and the reliability of the slider 34 driving the control block 41 is improved. In this embodiment, the spiral direction of the internal thread section 24 and the slide groove 42 are both clockwise. When the pressure rod 3 moves toward the control block 41, the slider 34 enters the slide groove 42, and then the slider 34 slides along the spiral slide groove 42. Since the pressure rod 3 cannot rotate an angle, the control block 41 rotates counterclockwise, thereby driving the valve block 4 to rotate counterclockwise, thereby twisting the valve block 4 in the direction away from the cavity 21, so that the valve block 4 produces a rotational concave movement in the cavity 21.

[0035] Reference Figure 3 , multiple guide rods 43 are fixed on the end surface of the valve block 4 facing the control block 41, and a limit plate 44 is fixed on the guide rod 43. The guide rod 43 is slidably connected with the control block 41. A limit groove 45 for the limit plate 44 to slide is provided in the control block 41. Springs 46 are provided on both sides of the limit plate 44, and the other end of the spring 46 contacts the end groove wall of the limit groove 45. Through the multiple guide rods 43, the valve block 4 and the control block 41 cannot rotate relative to each other, but can slide relative to each other; through the cooperation between the limit plate 44 and the limit groove 45, the valve block 4 and the control block 41 are prevented from separating, and the elastic force of the spring 46 drives the limit plate 44 to be located in the middle of the limit groove 45.

[0036] During the process of the control block 41 driving the valve block 4 to rotate, the distance between the control block 41 and the valve block 4 will change due to the axial displacement of the valve block 4. The valve block 4 is slidably connected to the control block 41 through the guide rod 43, so that the mechanism can operate normally. During the relative sliding process between the control block 41 and the valve block 4, the spring 46 adaptively expands and contracts.

[0037] The inner diameter of the port of the movable hole 23 located at the cavity 21 is the same as the outer diameter of the end of the valve block 4. When the end face of the valve block 4 is flush with the surface of the cavity 21, the valve block 4 blocks the movable hole 23, and the liquid plastic in the cavity 21 will not enter the movable hole 23 during injection molding.

[0038] The inner wall of the movable hole 23 is provided with an inclined groove 25, one end of which is arranged close to the mold cavity 21, and the other end of the inclined groove 25 is connected with the internal thread section 24. The valve block 4 is provided with a vent hole 1 47, which is used to connect with the inclined groove 25. When the valve block 4 is tightened on the internal thread section 24, the vent hole 1 47 and the inclined groove 25 are staggered. At least two inclined grooves 25 are provided along the circumference of the movable hole 23 to improve the ventilation volume and the uniformity of the jet. The control block 41 is provided with a vent hole 2 48, and the end of the vent hole 2 48 is directly opposite to the vent hole 1 47. The vent hole 2 48 is connected between the air cavity 22 and the vent hole 1 47 to make the gas flow smoothly.

[0039] Reference Figure 3 and Figure 6 A sealing gasket 5 is fixed on the end surface of the internal thread section 24 near the movable hole 23. The sealing gasket 5 is annular, and an escape opening is provided on the inner ring wall of the sealing gasket 5. The position of the escape opening corresponds to the inclined groove 25. When the valve block 4 is tightened on the internal thread section 24, the port of the vent hole 47 is pressed against the surface of the sealing gasket 5. At the same time, the vent hole 47 is staggered with the inclined groove 25 to prevent the air in the air cavity 22 from entering the movable hole 23. When the valve block 4 is loosened outside the internal thread section 24, the vent hole 47 and the inclined groove 25 are gradually connected to each other as the valve block 4 rotates. The valve block 4 moves away from the cavity 21, and the inclined groove 25 connects the vent hole 47 with the cavity 21, thereby starting the jet.

[0040] It should be noted that the above-mentioned structures such as the pressure rod 3 and the air cavity 22 can be provided in multiple sets as required, so as to perform air blowing and demoulding on multiple parts of the product to adapt to large-sized plastic products.

[0041] Example

[0042] A thin-walled plastic box forming process, using a thin-walled plastic box forming device of embodiment 1, comprises the following steps: Step S1: mold closing. As the movable mold 2 approaches the fixed mold 13 , the pressure rod 3 gradually moves away from the air cavity 22 , so that the air pressure in the air cavity 22 decreases, and air is introduced into the air cavity 22 through the one-way valve 32 .

[0043] Step S2: After the mold is closed, the injection machine 11 injects liquid plastic into the mold cavity 21 .

[0044] Step S3: After the plastic solidifies, the mold is opened, and as the movable mold 2 moves away from the fixed mold 13, the pressure rod 3 moves deep into the air cavity 22, so that the air pressure in the air cavity 22 increases.

[0045] Step S4: When the slider 34 slides into the slide groove 42, the control block 41 rotates through the spiral slide groove 42, and then drives the valve block 4 to rotate. The valve block 4 moves away from the cavity 21 through the threaded connection with the internal thread section 24. Figure 6The inclined groove 25 connects the vent hole 47 with the mold cavity 21 to open the movable hole 23, and the compressed gas in the air cavity 22 is ejected from the movable hole 23 to demould the product.

[0046] During the reset process, the above actions are performed in reverse, so they will not be described in detail here.

[0047] In summary, through the molding equipment and molding process of the thin-walled plastic box, the valve block 4 starts to spray after it is recessed into the cavity 21, avoiding the problem of the air valve component pushing out of the cavity 21 and damaging the surface of the thin-walled plastic box, and the valve block 4 rotates while moving inward, and the end face of the valve block 4 can be quickly separated from the plastic product, avoiding problems such as deformation or wire drawing caused by pulling the plastic; and the molding equipment and molding process themselves can compress the air for blowing and demolding, and the blowing operation can be automatic, does not rely on electronic control, and does not require external compressed air.

[0048] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A molding device for a thin-walled plastic box, comprising a base (1), an injection molding machine (11), a fixed seat (12), a fixed mold (13) and a movable mold (2), wherein the fixed mold (13) is fixedly connected to an output end of the injection molding machine (11), the movable mold (2) is slidably arranged on the base (1), and a cavity (21) is arranged on one side of the movable mold (2) and the fixed mold (13) facing each other, characterized in that: A pressure rod (3) is fixed on the fixed seat (12) toward the movable mold (2) side, the movable mold (2) is provided with an air cavity (22) for the pressure rod (3) to be slidably connected, a sealing ring (31) is provided between the pressure rod (3) and the inner wall of the air cavity (22), the inner wall of the cavity (21) is provided with a movable hole (23) communicating with the air cavity (22), a valve block (4) is arranged in the movable hole (23), an internal thread section (24) is provided in the movable hole (23) near the inner wall of the cavity (21), the outer wall of the valve block (4) is threadedly connected to the internal thread section (24), the valve block (4) is connected to a control block (41), the side wall of the control block (41) is provided with a spiral slide groove (42), a connecting rod (33) is fixed at the end of the pressure rod (3), a sliding block (34) is fixed at the end of the connecting rod (33), and the sliding groove (42) is used for sliding cooperation with the sliding block (34).

2. A thin-walled plastic box forming device according to claim 1, characterized in that: The pressure rod (3) is arranged to penetrate the fixing seat (12); the interior of the pressure rod (3) is hollow and both ends are connected; and a one-way valve (32) is fixed to one end of the pressure rod (3) away from the connecting rod (33).

3. The thin-walled plastic box forming device according to claim 1, characterized in that: The inner wall of the movable hole (23) is provided with an inclined groove (25), one end of the inclined groove (25) is arranged close to the mold cavity (21), and the other end of the inclined groove (25) is communicated with the internal thread section (24). The valve block (4) is provided with a vent hole (47) running through it, and the vent hole (47) is used to communicate with the inclined groove (25). When the valve block (4) is tightened on the internal thread section (24), the vent hole (47) and the inclined groove (25) are staggered.

4. A thin-wall plastic box forming device according to claim 1, characterized in that: A plurality of guide rods (43) are fixed on the end surface of the valve block (4) facing the control block (41), a limit plate (44) is fixed on the guide rods (43), the guide rods (43) are slidably connected to the control block (41), a limit groove (45) for the limit plate (44) to slide is provided in the control block (41), and springs (46) are provided on both sides of the limit plate (44).

5. The thin-walled plastic box forming device according to claim 3, characterized in that: The control block (41) is provided with a second vent hole (48) extending therethrough, and the end of the second vent hole (48) is directly opposite to the first vent hole (47).

6. The thin-walled plastic box forming device according to claim 3, characterized in that: A sealing gasket (5) is fixed on the end surface of the internal thread section (24) close to the movable hole (23). The sealing gasket (5) is annular and an escape opening is provided on the inner ring wall of the sealing gasket (5). The position of the escape opening corresponds to the inclined groove (25).

7. The thin-wall plastic box forming device according to claim 3, characterized in that: At least two inclined grooves (25) are provided along the circumference of the movable hole (23).

8. The thin-walled plastic box forming device according to claim 1, characterized in that: At least two connecting rods (33) are provided along the circumference of the pressure rod (3), and at least two sliding grooves (42) are provided along the circumference of the control block (41).

9. The thin-wall plastic box forming device according to claim 1, characterized in that: An oil cylinder (14) is fixed on the fixed seat (12), and an output end of the oil cylinder (14) is fixed to the movable mold (2).

10. A molding process for a thin-walled plastic box, characterized in that: A thin-walled plastic box forming device according to any one of claims 1 to 9 comprises the following steps: Step S1: closing the mold, as the movable mold (2) approaches the fixed mold (13), the pressure rod (3) gradually moves away from the air cavity (22), so that the air pressure in the air cavity (22) decreases, and air is introduced into the air cavity (22) through the one-way valve (32); Step S2: After the mold is closed, the injection machine (11) injects liquid plastic into the mold cavity (21); Step S3: After the plastic solidifies, the mold is opened, and as the movable mold (2) moves away from the fixed mold (13), the pressure rod (3) moves deep into the air cavity (22), thereby increasing the air pressure in the air cavity (22); Step S4: When the slider (34) slides into the slide groove (42), the control block (41) is rotated through the spiral slide groove (42), thereby driving the valve block (4) to rotate. The valve block (4) moves away from the cavity (21) through the threaded connection with the internal thread section (24), thereby opening the movable hole (23), and the compressed gas in the air cavity (22) is ejected from the movable hole (23) to demould the product.

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