An injection mold with no ejection and easy demoulding and an injection molding method thereof

Abstract

The present invention discloses an injection mold with no ejection and easy demoulding and an injection molding method thereof, wherein the injection mold comprises a fixed mold and a movable mold, a cavity is formed on the fixed mold, a core is formed on the movable mold, an injection film covering the cavity is arranged on the fixed mold, a suction and discharge pipe is arranged on the fixed mold, and the suction and discharge pipe is connected to an external gas generating device with suction and inflation functions; the injection molding method comprises the following steps: mold closing, a gas generating device blows gas into the cavity, and the injection film is completely wrapped outside the core; the gas in the cavity is sucked away, a vacuum area is formed between the injection film and the core, and the injection film is seamlessly attached to the inner wall of the cavity; injection molding; mold opening; demoulding, cold air is blown between the inner wall of the cavity and the injection film, the injection film is separated from the inner wall of the cavity, and the injection film lifts the product; the product is taken out and unloaded. The present invention provides an injection mold with no ejection and easy demoulding and an injection molding method thereof, which overcomes the technical defects of ejector demoulding and improves the demoulding effect of the product after injection molding.

Description

Technical Field

[0001] The invention belongs to the field of injection molds, and in particular relates to an injection mold with no ejection and easy demoulding, and an injection molding method thereof. Background Art

[0002] Injection molds are common plastic parts molding equipment. The working principle of the injection mold is to set a fixed mold on the workbench, with a molding cavity on the upper side of the fixed mold, a support frame on the upper side of the workbench, a hydraulic cylinder on the upper side of the support frame, and the output shaft of the hydraulic cylinder passes through the support frame and is provided with a movable mold matching the fixed mold. When the hydraulic cylinder is working, the movable mold is buckled with the fixed mold, and the molding part on the lower side of the fixed mold is combined with the molding cavity to form a mold cavity for the plastic part. Then, liquefied plastic is injected into the molding cavity through the injection tube. After the liquefied plastic is cooled, a plastic part is formed. At this time, the movable mold can be separated from the fixed mold to take out the plastic part.

[0003] The existing demoulding method of injection molds generally adopts the ejector pin method. The defects of ejector pin demoulding are: it is necessary to reasonably design the position of the ejector pin on the product according to the characteristics of the product. When the product volume is relatively small or the shape is relatively special, it will be difficult to design the ejector pin demoulding. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an injection mold and an injection molding method thereof which are easy to demold without ejection and the status quo of the prior art, abandon the traditional ejector demolding method, overcome the technical defects of ejector demolding, and at the same time, simplify the demolding design of the injection mold and improve the demolding effect of the product after injection molding.

[0005] The technical solution adopted by the present invention to solve the above technical problems is: an injection mold with no ejection and easy demolding, including a fixed mold and a movable mold, a cavity is formed on the fixed mold, and a core is formed on the movable mold, characterized in that: an injection film covering the cavity is arranged on the fixed mold, a suction and exhaust pipe is arranged on the fixed mold, the suction and exhaust pipe is connected to an external gas generating device with suction and inflation functions, a sealing part is rotatably arranged on the suction and exhaust pipe close to the inner wall of the cavity, and a connecting hole for connecting with the suction and exhaust pipe is opened on the sealing part.

[0006] As an improvement, a sealing ring is formed on the movable mold outside the core, and a sealing groove matched with the sealing ring is formed on the fixed mold outside the cavity.

[0007] Further improvement, the injection film is elastic and has a planar structure. At least two adjustment mechanisms are radially arranged on the top surface of the fixed mold. The adjustment mechanism includes a slider, a connecting rod connected to the slider, and a fixing piece. A slide groove compatible with the slider is radially arranged on the fixed mold, the slider is limited in the slide groove, the injection film is connected to the connecting rod, and the fixing piece is arranged on the connecting rod for fixing and pressing the injection film. The movable mold is provided with an avoidance groove to avoid interference with the adjustment mechanism.

[0008] As a further improvement, an adapting portion is formed in the middle of the injection film which adapts to the inner wall of the cavity in a natural state, a mold top which adapts to the top of the fixed mold is formed on the periphery of the adapting portion on the injection film, a mold outer portion bent at the outer peripheral wall of the fixed mold is formed on the periphery of the mold top, and a connecting piece for fixing the injection film to the side wall of the fixed mold is provided between the mold outer portion and the side wall of the fixed mold.

[0009] As a further improvement, the movable mold is provided with a blowing pipe radially outside the core, an arc groove matched with the outer wall of the blowing pipe is formed on the top surface of the movable mold, and the blowing pipe is connected to the gas generating device.

[0010] As a further improvement, the injection film extends to the pouring channel and comes out from the gate of the injection mold, and a push plate is slidably arranged at the pouring channel on the fixed mold, and the top surface shape of the push plate is adapted to the pouring channel.

[0011] In addition, the present invention also discloses an injection molding method using the injection mold without ejection and easy demoulding, which is characterized by comprising the following steps:

[0012] Step S1, the movable mold moves downward for a certain distance, the injection film contacts the core, and the gas generating device blows gas into the cavity, so that the injection film is completely wrapped around the core;

[0013] Step S2, the movable mold continues to move downward for a short distance, the movable mold and the fixed mold are completely closed, and the periphery of the injection film is pressed tightly between the movable mold and the fixed mold;

[0014] Step S3, the sealing member rotates, the connecting hole of the sealing member is connected to the suction and discharge pipe, the gas generating device sucks air, and under the action of the gas generating device, the injection film moves toward the inner wall of the cavity, sucks away the gas in the cavity, and forms a vacuum area between the injection film and the core, and the injection film is seamlessly attached to the inner wall of the cavity;

[0015] Step S4, injection molding, the sealing member is reset, the sealing member blocks the connecting hole and the suction and discharge pipe, the molten plastic is injected into the area between the injection molding film and the core, the pressure is maintained and the injection molding film and the inner wall of the cavity are seamlessly attached;

[0016] Step S5, opening the mold, the movable mold moves upward, and the movable mold core and the product are separated;

[0017] Step S6, demoulding, the sealing part rotates again, and the gas generating device blows cold air between the inner wall of the cavity and the injection film, so that the injection film and the inner wall of the cavity are separated, and as the amount of gas blown increases, the space between the injection film and the cavity becomes larger, and the pressure also increases, so that the injection film lifts the product;

[0018] Step S7, taking out the product and unloading.

[0019] As an improvement, in step S5, while the movable mold is moving upward, the gas generating device blows cold air into the blowing pipe, and the cold air enters the gap between the product and the injection molding film.

[0020] As a further improvement, in step S4, the push plate moves upward by a certain distance, so that the pouring channel becomes narrower.

[0021] Compared with the prior art, the advantages of the present invention are: abandoning the traditional demolding method of ejector pins, by arranging an injection molding film on the fixed mold cavity, not only can a negative pressure be formed between the core and the injection molding film during the plastic pouring process, which is convenient for injecting molten plastic into the cavity, but also under the action of high pressure holding, the injection molding film and the inner wall of the cavity are completely fitted, and the injection molding film and the inner wall of the cavity form the same shape, which does not affect the injection shape of the product; and, in the demolding process, by injecting high-pressure cold air between the inner wall of the cavity and the injection molding film, the product and the cavity can be lifted up to realize the demolding of the product. The present invention only needs to add an injection molding film to the fixed mold, eliminating the design of the demolding mechanism of the traditional injection mold, overcoming the technical defects of ejector pin demolding, and improving the demolding effect of the product after injection molding. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the structure of an injection mold without ejection and easy demoulding in an embodiment of the present invention;

[0023] Figure 2 The figure is a schematic diagram of the arrangement structure of the blowing pipe in the injection mold with no ejection and easy demoulding in the embodiment of the present invention. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below with reference to the accompanying drawings.

[0025] like Figure 1 and 2 As shown, the injection mold with no ejection and easy demoulding in this embodiment includes a fixed mold 1, a movable mold 2, an injection film 3, a suction and discharge pipe 4, a gas generating device, a sealing part 5, a blowing pipe 7 and an adjusting mechanism.

[0026] Among them, a cavity 11 is formed on the fixed mold 1, a core 21 is formed on the movable mold 2, an injection film 3 covering the cavity 11 is provided on the fixed mold 1, a suction and discharge pipe 4 is provided on the fixed mold 1, the suction and discharge pipe 4 is connected to an external gas generating device with suction and inflation functions, a sealing member 5 is rotatably provided on the suction and discharge pipe 4 near the inner wall of the cavity, and a connecting hole 51 for connecting with the suction and discharge pipe 4 is opened on the sealing member 5. The sealing member 5 can adopt a spherical or columnar structure.

[0027] Furthermore, in order to improve the sealing effect of the injection film 3 during the closing process of the movable mold and the fixed mold, a sealing ring 22 is formed on the movable mold 2 outside the core 21, and a sealing groove 12 adapted to the sealing ring 22 is formed on the fixed mold 1 outside the cavity 11. When the movable mold 2 and the fixed mold 1 are closed, the sealing ring 22 is inserted into the sealing groove 12, so that the local injection film 3 is also stuck in the sealing groove 12, thereby avoiding air leakage during the suction or exhaust process of the suction and exhaust pipe 4.

[0028] In addition, in the embodiment of the present invention, the injection film 3 can be a planar structure or a special-shaped structure. For the case where the cavity depth is shallow, the injection film 3 with a planar structure can be used, and the injection film 3 is required to be elastic. At the same time, in order to adjust the deformation amount of the injection film 3 entering the cavity 11, at least two adjustment mechanisms are radially arranged on the top surface of the fixed mold 1, and the adjustment mechanism includes a slider 61, a connecting rod 62 connected to the slider 61, and a fixing member 63. A slide groove 13 adapted to the slider 61 is radially arranged on the fixed mold 1, and the slider 61 is limited in the slide groove 13. The injection film 3 is connected to the connecting rod 62, and the fixing member 63 is arranged on the connecting rod 62 for fixing and pressing the injection film 3. The movable mold 2 is provided with an avoidance groove 23 to avoid interference with the adjustment mechanism. When the sliders 61 slide toward the inner direction of the cavity 11, the elastic deformation of the injection film 3 can be reduced during the injection molding process; otherwise, the opposite is true.

[0029] In addition, for those cavities 11 with a relatively deep depth, the elastic deformation capacity of the injection film 3 can be reduced, and the injection film 3 can adopt a special-shaped structure. Specifically, the middle part of the injection film 3 is formed with an adapting part that matches the inner wall of the cavity 11 in a natural state, and the injection film 3 is located on the periphery of the adapting part. A mold top that matches the top of the fixed mold 1 is formed, and the outer periphery of the mold top is formed with a mold outside that is bent on the outer peripheral wall of the fixed mold 1. A connector for fixing the injection film 3 to the side wall of the fixed mold 1 is provided between the mold outside and the side wall of the fixed mold 1. When the injection film 3 is formed, it is necessary to use the cavity structure on the fixed mold 1, and use the cavity structure of the fixed mold 1 to make the structure of the injection film 3.

[0030] Furthermore, in order to reduce the adhesion between the injection film 3 and the product during demoulding, a blow pipe 7 is radially arranged on the outside of the core on the movable mold 2, and an arc groove matching the outer wall of the blow pipe 7 is formed on the top surface of the movable mold 2. The blow pipe 7 is connected to the gas generating device. When the movable mold 2 and the fixed mold 1 are molded together, the blow pipe 7 is mounted on the arc groove.

[0031] Furthermore, the injection film 3 extends to the pouring channel and comes out from the gate of the injection mold. A push plate is slidably provided at the pouring channel on the fixed mold 1, and the top surface shape of the push plate is adapted to the pouring channel. When the injection mold is injection-molded and pressure-maintained, the push plate rises a certain distance, so that the pouring channel becomes narrower. On the one hand, the amount of waste on the product is reduced; on the other hand, the pressure-maintaining pressure is increased during the pressure-maintaining process. Preferably, the top surface of the push plate is inclined downward from the gate to the cavity, so that after the push plate rises, the cross-sectional area of ​​the pouring channel gradually increases from the gate to the cavity.

[0032] Finally, the present invention also discloses an injection molding method using the injection mold with no ejection and easy demoulding, comprising the following steps:

[0033] Step S1, the movable mold 2 moves downward for a certain distance, the injection film 3 contacts the core 21, and the gas generating device blows gas into the cavity 11, so that the injection film 3 is completely wrapped around the core 21;

[0034] Step S2, the movable mold 2 continues to move downward for a short distance, the movable mold 2 and the fixed mold 1 are completely molded together, and the outer periphery of the injection film 3 is pressed tightly between the movable mold 2 and the fixed mold 1;

[0035] Step S3, the sealing member 5 rotates, the connecting hole 51 of the sealing member 5 is connected to the suction and discharge pipe 4, the gas generating device sucks air, and under the action of the gas generating device, the injection film 3 moves toward the inner wall of the cavity 11, sucking away the gas in the cavity 11, forming a vacuum area between the injection film 3 and the core 21, and the injection film 3 is seamlessly attached to the inner wall of the cavity 11;

[0036] Step S4, injection molding, the sealing member 5 is reset, the sealing member 5 blocks the connecting hole 51 and the suction and discharge pipe 4, the molten plastic is injected into the area between the injection molding film 3 and the core 21, and the pressure is maintained for molding, and the injection molding film and the inner wall of the cavity are seamlessly attached;

[0037] Step S5, opening the mold, the movable mold 2 moves upward, and the core 21 of the movable mold 2 is separated from the product;

[0038] Step S6, demoulding, the sealing member 5 rotates again, the gas generating device blows cold air between the inner wall of the cavity 11 and the injection film 3, the injection film 3 and the inner wall of the cavity 11 are separated, and as the amount of gas blown increases, the space between the injection film 3 and the cavity 11 becomes larger, and the pressure also increases, and the injection film 3 lifts the product;

[0039] Step S7, taking out the product and unloading.

[0040] Furthermore, in step S5 or S6 , while the movable mold 2 moves upward, the gas generating device blows cold air into the blowing pipe 7 , and the cold air enters into the gap between the product and the injection molding film 3 .

[0041] Furthermore, in step S4, the push plate moves upward a certain distance to narrow the pouring channel. On the one hand, the amount of waste on the product is reduced; on the other hand, the pressure holding pressure is increased during the pressure holding process. Preferably, the top surface of the push plate is inclined downward from the gate to the cavity, so that after the push plate rises, the cross-sectional area of ​​the pouring channel gradually increases from the gate to the cavity.

[0042] In summary, the traditional demolding method of ejector pin is abandoned, and an injection film 3 is arranged on the cavity 11 of the fixed mold 1, which can not only form a negative pressure between the core 21 and the injection film 3 during the plastic pouring process, and facilitate the injection of molten plastic into the cavity 11, but also, under the action of high pressure holding, the injection film 3 and the inner wall of the cavity 11 are completely fitted, and the injection film 3 and the inner wall of the cavity 11 form the same shape, which does not affect the injection shape of the product; moreover, in the demolding process, by injecting high-pressure cold air between the inner wall of the cavity 11 and the injection film 3, the product and the cavity 11 can be lifted up to realize the demolding of the product. The present invention only needs to add an injection film 3 to the fixed mold 1, which eliminates the design of the demolding mechanism of the traditional injection mold, overcomes the technical defects of ejector pin demolding, and improves the demolding effect of the product after injection molding.

Claims

1. An injection molding method for an injection mold with no ejection and easy demoulding, wherein: The non-ejection easy-to-demold injection mold comprises a fixed mold (1) and a movable mold (2), wherein a cavity (11) is formed on the fixed mold (1), and a core (21) is formed on the movable mold (2), and is characterized in that: an injection film (3) covering the cavity (11) is arranged on the fixed mold (1), a suction and discharge pipe (4) is arranged on the fixed mold (1), the suction and discharge pipe (4) is connected to an external gas generating device with suction and inflation functions, a sealing member (5) is rotatably arranged on the suction and discharge pipe (4) near the inner wall of the cavity (11), and a connecting hole (51) for connecting with the suction and discharge pipe (4) is opened on the sealing member (5); The injection molding film (3) is elastic and has a planar structure. At least two adjustment mechanisms are radially arranged on the top surface of the fixed mold (1). The adjustment mechanism comprises a slider (61), a connecting rod (62) connected to the slider (61), and a fixing member (63). A slide groove (13) adapted to the slider (61) is radially arranged on the fixed mold (1). The slider (61) is limited in the slide groove (13). The injection molding film (3) is connected to the connecting rod (62). The fixing member (63) is arranged on the connecting rod (62) to fix and press the injection molding film (3). The movable mold (2) is provided with an avoidance groove (23) to avoid interference with the adjustment mechanism. The injection film (3) extends to the pouring channel and comes out from the gate of the injection mold. A push plate is slidably arranged at the pouring channel on the fixed mold (1), and the top surface shape of the push plate is adapted to the pouring channel. The injection molding method comprises the following steps: Step S1, the movable mold (2) moves downward a certain distance, the injection molding film (3) contacts the core (21), and the gas generating device blows gas into the cavity (11), so that the injection molding film (3) is completely wrapped around the core (21); Step S2, the movable mold (2) continues to move downward for a short distance, the movable mold and the fixed mold (1) are completely closed, and the periphery of the injection molding film (3) is pressed tightly between the movable mold (2) and the fixed mold (1); Step S3, the sealing member (5) rotates, the connecting hole (51) of the sealing member (5) is connected to the suction and discharge pipe (4), the gas generating device sucks air, and under the action of the gas generating device, the injection molding film (3) moves toward the inner wall of the cavity (11), sucks away the gas in the cavity (11), and forms a vacuum area between the injection molding film (3) and the core, and the injection molding film (3) is seamlessly attached to the inner wall of the cavity (11); Step S4, injection molding, the sealing member (5) is reset, the sealing member (5) blocks the connecting hole (51) and the suction and discharge pipe (4), the molten plastic is injected into the area between the injection molding film (3) and the core (21), and the pressure is maintained to form the injection molding film 3 and the inner wall of the cavity 11 are seamlessly attached; Step S5, opening the mold, the movable mold (2) moves upward, and the core (21) of the movable mold (2) and the product are separated; Step S6, demoulding, the sealing member (5) rotates again, and the gas generating device blows cold air into the space between the inner wall of the cavity (11) and the injection film (3), so that the injection film (3) and the inner wall of the cavity (11) are separated, and as the amount of gas blown in increases, the space between the injection film (3) and the cavity (11) becomes larger, and the pressure also increases, so that the injection film (3) lifts up the product; Step S7, taking out the product and unloading; In step S4, the push plate moves upward a certain distance to narrow the pouring channel.

2. The method for molding an injection mold without ejection and easy demoulding according to claim 1, characterized in that: A sealing ring (22) is formed on the movable mold (2) outside the core (21), and a sealing groove (12) adapted to the sealing ring (22) is formed on the fixed mold (1) outside the cavity (21).

3. The method for molding an injection mold without ejection and easy demoulding according to claim 2, characterized in that: The movable mold (2) is radially provided with a blowing pipe (7) outside the core (21), and an arc-shaped groove matching the outer wall of the blowing pipe (7) is formed on the top surface of the movable mold (2), and the blowing pipe (7) is connected to a gas generating device.

4. The method for molding an injection mold without ejection and easy demoulding according to claim 3, characterized in that: In the step S5, while the movable mold (2) is moving upward, the gas generating device blows cold air into the blowing pipe (7), and the cold air enters the gap between the product and the injection molding film (3).

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