Inverted Mold and Injection Molding Method

Abstract

The present invention provides an inverted mold and an injection molding method, which can solve the problems in the prior art that the end of the moving mold of the inverted mold sinks due to the action of gravity, resulting in poor mold clamping and wear of the mating surfaces of the moving mold and the stationary mold. The inverted mold includes a moving mold and a stationary mold. The moving mold includes a core and a moving template, and the stationary mold includes a cavity and a stationary mold base plate. The core and the cavity cooperate to form a molding space; the core is an aluminum core, and a support device is provided in the moving mold. The support device can expand and contract along the mold opening and closing direction. Before the rubber material fills the molding space at the initial stage of mold clamping, the support device is in the extended state and the telescopic end abuts against the inner wall of the cavity. The moving mold core being an aluminum core reduces the overall weight of the moving mold, effectively alleviates the problem of the sinking and deformation of the moving mold part of the mold due to the action of gravity, and reduces the wear of the mating surfaces of the moving mold and the stationary mold; by providing a support device in the moving mold, the main mold clamping force is borne during mold clamping, compensating for the defect that the pressure resistance of the aluminum core is lower than that of the steel core.

Description

Technical Field

[0001] The present invention belongs to the technical field of injection molds, and particularly relates to a structural improvement of an inverted mold and an injection molding method using the inverted mold for injection molding. Background Art

[0002] As a tool for producing plastic products, an injection mold can endow plastic products with a complete structure and precise dimensions. An injection mold generally consists of a moving mold and a fixed mold. The moving mold is installed on the moving template of an injection molding machine, and the fixed mold is installed on the fixed template of the injection molding machine. Due to the special structure of the finished product or the appearance requirements of the finished product, the gate and ejection are on the same side of the finished product. Such a mold structure is called an inverted mold.

[0003] For example, in order to improve the appearance quality of the housing products of a television or a display device, the mold for manufacturing the housing of the television and the display device generally needs to use an inverted mold, that is, the hot runner is installed on one side of the core of the moving mold of the injection mold. Since the structure of the moving mold is inherently more complex and heavier than that of the stationary mold, after inversion, that is, after installing the hot runner-related structure on the moving mold, the structure of the moving mold is more complex than that of the stationary mold, and the weight is further increased. The suspended range of the moving mold is large. According to the cantilever beam principle of material mechanics, the moving mold part will sink at the end due to the action of gravity, resulting in poor mold closing effect. For example, the phenomenon of mold closing misalignment leads to a high defective rate of products, and after multiple injections, the mating surface between the moving mold and the stationary mold will be severely worn, seriously affecting the service life of the mold.

[0004] Since the stiffness of the injection molding machine itself is certain, the weight of the core part at the end of the moving mold of the injection mold is the main factor affecting the sinking of the moving mold of the injection mold. Therefore, how to reduce the weight of the moving mold of the inverted mold as much as possible on the basis of ensuring the injection molding quality, so as to solve the problems of poor mold closing caused by the sinking of the end of the moving mold and serious wear of the mating surface between the moving mold and the stationary mold as much as possible. Summary of the Invention

[0005] The present invention provides an inverted mold and an injection molding method, which can solve the problems of poor mold closing caused by the sinking of the end of the moving mold of the inverted mold under the action of gravity and serious wear of the mating surface between the moving mold and the stationary mold in the prior art.

[0006] In some embodiments of the present application, an inverted mold is proposed, which includes a moving mold and a fixed mold. The moving mold includes a core and a moving template fixedly connected to the core as a whole. The fixed mold includes a steel cavity and a fixed mold base plate fixedly connected to the cavity as a whole. The core and the cavity cooperate to form a molding space. The core is an aluminum core, and a supporting device is provided in the moving mold. The supporting device can stretch along the mold opening and closing direction so that its telescopic end can extend into the molding space or retract out of the molding space. Before the rubber material fills the molding space after mold closing, the supporting device is in an extended state and the telescopic end abuts against the inner wall of the cavity.

[0007] In some embodiments of the present application, the number of the supporting devices is multiple, and the multiple supporting devices are evenly distributed along the circumferential edge of the molding space.

[0008] In some embodiments of the present application, a through avoidance portion for avoiding the supporting device is formed on the core. The supporting device is fixedly arranged at the moving template, and the telescopic end extends into the molding space or retracts out of the molding space through the through avoidance portion.

[0009] In some embodiments of the present application, when the supporting device retracts out of the molding space, the end face of the telescopic end is flush with the surface of the core, and the circumferential side face of the telescopic end is in sealing cooperation with the through avoidance portion.

[0010] In some embodiments of the present application, the supporting device includes an oil cylinder and a telescopic component. The oil cylinder is fixedly arranged inside the moving mold, the telescopic component is fixedly connected to the piston rod of the oil cylinder, and the oil cylinder can drive the telescopic component to stretch along the mold opening and closing direction.

[0011] In some embodiments of the present application, the moving template is an aluminum plate, and wear-resistant and pressure-resistant inserts located outside the molding space and surrounding the molding space for at least one week are provided on the moving mold parting surface of the moving template.

[0012] In some embodiments of the present application, the wear-resistant and pressure-resistant inserts are flush with the moving mold parting surface.

[0013] In some embodiments of the present application, the core is a high-strength aluminum core, and the moving template is a high-strength aluminum plate.

[0014] In some embodiments of the present application, an elastic buffer component is covered on the telescopic end.

[0015] In some embodiments of the present application, an injection molding method for an inverted mold is also proposed, including the following steps:

[0016] (1) The supporting device extends before or at the same time as the mold is closed.

[0017] (2) Before the rubber compound is filled into the molding space after the mold is closed, the support device remains extended and its telescopic end abuts against the inner wall of the cavity.

[0018] (3) The rubber compound continues to be filled and reaches the molding space, and the support device retracts out of the molding space until the end face of its telescopic end is flush with the surface of the core.

[0019] (4) The rubber compound continues to be filled until the entire molding space is filled, and the filling ends.

[0020] (5) Hold pressure, cool, open the mold, and demold.

[0021] Compared with the prior art, the present invention has the following advantages and positive effects:

[0022] 1. The moving mold core is an aluminum core, which reduces the overall weight of the moving mold, decreases the torque, effectively alleviates the problem of the sinking and deformation of the moving mold part of the mold due to the action of gravity, improves the mold closing effect, reduces the wear of the mating surfaces of the moving mold and the stationary mold, and thus ensures the stability of the mold.

[0023] 2. During the mold closing and injection molding process, due to the large mold closing force, by arranging a support device in the moving mold, the support device can expand and contract along the mold opening and closing direction. Before the rubber compound is filled into the molding space at the initial stage of mold closing, the support device is in the extended state and its telescopic end abuts against the inner wall of the cavity, so as to bear the main mold closing force during mold closing.

[0024] 3. During the mold closing and rubber compound filling stage, the support device can retract out of the molding space, transfer the mold closing force to be jointly borne by the mold parting surface and the plastic melt, and correspondingly reduce the mold closing force borne by the aluminum core. Then, by arranging the support device, the aluminum core can also meet the pressure resistance requirements during the injection molding process, making up for the defect that the pressure resistance of the aluminum core is lower than that of the steel core, and improving the service life of the aluminum core. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] Figure 1 It is a schematic structural diagram of the inverted mold of the present invention;

[0027] Figure 2 It is a schematic structural diagram of the moving mold of the inverted mold of the present invention;

[0028] Figure 3Schematic structural diagram of the wear-resistant and pressure-resistant insert on the moving template of the flip-chip mold of the present invention;

[0029] Figure 4 is Figure 3 A-A cross-sectional view.

[0030] Reference numerals: 10 - moving die; 11 - core; 12 - moving template; 13 - hot runner plate; 14 - moving die base plate; 15 - leg; 16 - through avoidance part; 17 - wear-resistant and pressure-resistant insert; 18 - moving die parting surface; 19 - annular groove; 20 - fixed die; 21 - cavity; 22 - fixed die base plate; 30 - molding space; 40 - support device; 41 - telescopic end; 42 - oil cylinder; 43 - telescopic member. Specific embodiments

[0031] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the accompanying drawings. In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "horizontal", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0032] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0033] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0034] Figure 1 is the structural schematic diagram of the flip-chip mold in this embodiment, Figure 2 is the structural schematic diagram of the moving die of the flip-chip mold in this embodiment. Refer to Figure 1 and Figure 2The flip mold of this embodiment includes a movable mold 10 and a fixed mold 20. The movable mold 10 includes a core 11 and a movable mold plate 12 fixedly connected to the core 11 as a whole, and of course also includes a hot runner plate 13, a movable mold base plate 14 and a plurality of legs 15. The fixed mold 20 includes a steel cavity 21 and a fixed mold base plate 22 fixedly connected to the cavity 21 as a whole. The fixed mold base plate 22 is also a steel plate. The core 11 and the cavity 21 cooperate to form a molding space 30.

[0035] Different from the prior art, the core 11 in this embodiment is an aluminum core, that is, the material is aluminum, and a supporting device 40 is provided in the movable mold 10, which can be moved along the mold opening and closing direction (such as Figure 1 The supporting device 40 is retractable (in the direction of the arrow shown) so that its retractable end 41 can extend into the molding space 30 or retract out of the molding space 30. In the initial stage of mold closing during the injection molding process, before the rubber material reaches the molding space 30, that is, at this stage, the mold has been closed but the rubber material has not reached the molding space 30, the supporting device 40 is in an extended state and its retractable end 41 abuts against the inner wall of the cavity 21.

[0036] In this embodiment, the core 11 on the movable mold 10 is made of aluminum, which reduces the overall weight of the movable mold 10. This is particularly true because the core 11 is located at the end of the movable mold 10. The lightweight aluminum core also reduces the torque of the movable mold 10, effectively alleviating the problem of the movable mold portion sinking and deforming due to gravity. This improves the mold closing effect and reduces wear on the mating surfaces of the movable mold 10 and the static mold 20, thereby ensuring mold stability. Furthermore, the aluminum core 11 improves mold cooling and processing efficiency, shortens molding time, and reduces energy consumption.

[0037] In addition, during the mold closing and injection molding process, since the mold closing force is very large, and the pressure resistance (i.e., strength) of aluminum is seriously lower than that of steel, in order to compensate for the defect that the pressure resistance of the aluminum core 11 in this embodiment is lower than that of the original steel core, this embodiment sets the above-mentioned support device 40 in the movable mold 10. The support device 40 can be extended along the mold opening and closing direction. In the initial stage of mold closing, before the rubber material is filled and reaches the molding space, the support device 40 is in an extended state and its extended end is against the inner wall of the cavity 21, thereby supporting the surface of the cavity 21 during mold closing and bearing most of the mold closing force, which correspondingly reduces the pressure of the aluminum core. 11 is subjected to the clamping pressure; in the clamping injection molding compound filling stage, the support device 40 can be retracted and separated from the molding space 30, and the clamping force is transferred to the mold parting surface and the plastic melt to share, which also correspondingly reduces the clamping force borne by the aluminum core 11. By setting the support device 40, the aluminum core 11 can also meet the pressure resistance requirements of the injection molding process, making up for the defect that the pressure resistance of the aluminum core 11 is lower than that of the steel core, and improving the service life of the aluminum core, thereby making up for the defect that the pressure resistance of the aluminum core is lower than that of the steel core, and improving the service life of the aluminum core.

[0038] Specifically, the support device 40 is made of mold steel material, and when it is configured to be in an extended state, its telescopic end 41 is mainly supported against a molding surface that has no appearance requirements.

[0039] In order to reliably support the aluminum core 11, especially to increase the supporting force of the core 11 when the volume of the molded product is large, in some embodiments of the present application, the number of supporting devices 40 can be multiple, and the multiple supporting devices 40 can be evenly distributed along the circumferential edge of the molding space 30, that is, evenly supported at the circumferential edge of the product to avoid indentation on the main appearance surface of the product as much as possible.

[0040] In order to further prevent the support device 40 from causing indentations on the product's exterior surface, an elastic buffer component, such as a rubber pad, may be coated on the telescopic end 41 thereof.

[0041] In some embodiments of the present application, Figure 2 As shown, a through avoidance portion 16 for avoiding the support device 40 is formed on the core 11, specifically a through hole. The support device 40 is fixed to the movable mold plate 12, and its telescopic end 41 extends into the molding space 30 or retracts out of the molding space 30 through the through avoidance portion 16, so that the telescopic stroke of the support device 40 can be minimized as much as possible, and the volume and weight of the support device 40 can be reduced as much as possible, thereby minimizing the adverse effect on the weight of the movable mold 10.

[0042] Since the through avoidance portion 16 is provided, there is a risk of overflow through the through avoidance portion 16 during the rubber filling and injection molding process. To solve this problem, in this embodiment, when the support device 40 is retracted and separated from the molding space 30, the support device 40 is retracted to Figure 2 In the position shown, the end surface of the telescopic end 41 is flush with the surface of the core 11, and the circumferential side surface of the telescopic end 41 seals against the through-passage 16. Therefore, when the support device 40 retracts and leaves the molding space 30, the telescopic end 41 precisely blocks the through-passage 16, thereby preventing the rubber from overflowing through the through-passage 16. Furthermore, the end surface of the telescopic end 41 is flush with the surface of the core 11, thereby ensuring the integrity of the molding space 30 and thus the molding quality of the product.

[0043] In this embodiment, the supporting device 40 includes a cylinder 42 and a retractable component 43. The cylinder 42 is fixed inside the movable mold 10, and the retractable component 43 is fixed to the piston rod of the cylinder 42. The cylinder 42 can drive the retractable component 43 to retract along the mold opening and closing direction.

[0044] Specifically, the oil cylinder 42 can be arranged on the moving template 12 or the hot runner plate 13, depending on the actual working conditions. For the case where the volume of the molded product is large, i.e., the volume of the molding space 30 is large, multiple supporting devices 40 can be arranged, or multiple telescopic components 43 can be simultaneously driven by the same oil cylinder 42, and the multiple telescopic components 43 are dispersedly arranged to improve the supporting force for the core 11.

[0045] In some embodiments of the present application, the supporting device 40 can also be selected as a gas spring, such as a nitrogen spring.

[0046] Figure 3 Schematic diagram of the structure of the wear-resistant and pressure-resistant insert on the moving template of the inverted mold in this embodiment, Figure 4 For Figure 3 the A-A sectional view. To further reduce the weight of the moving mold 10, in some embodiments of the present application, the moving template 12 is also selected as an aluminum plate. At this time, referring to Figure 3 and Figure 4 , a wear-resistant and pressure-resistant insert 17 located outside the molding space 30 and surrounding the molding space 30 for at least one week is provided on the moving mold parting surface 18 of the moving template 12.

[0047] The wear-resistant and pressure-resistant insert 17 can specifically be made of steel or other wear-resistant and pressure-resistant materials, sharing the clamping force during injection molding and closing, improving the pressure-bearing and wear-resistant properties of the material in this area, making up for the defect of low pressure resistance of the aluminum moving template 12, and improving the service life of the overall aluminum moving mold 10.

[0048] In this embodiment, the core 11 is specifically a high-strength aluminum core, and the moving template 12 is a high-strength aluminum plate, with low density and higher strength than ordinary aluminum materials, and is not easily deformed when bearing the clamping force.

[0049] Specifically, as Figure 4 shown, an annular groove 19 adapted to the wear-resistant and pressure-resistant insert 17 is formed on the moving mold parting surface 18, and the wear-resistant and pressure-resistant insert 17 is embedded in the annular groove 19 and is flush with the moving mold parting surface 18 to improve the closing effect and ensure the closing pressure.

[0050] Referring to Figures 1 to 4 , the injection molding method of the above-mentioned inverted mold in this embodiment includes the following steps:

[0051] (1) Before the mold is closed, the supporting device 40 extends, or the supporting device 40 extends while the mold is being closed;

[0052] (2) Before the rubber material fills the molding space 30 through the hot runner system in the initial stage after the mold is closed, the supporting device 40 remains extended and its telescopic end 41 abuts against the inner wall of the cavity 21;

[0053] (3) The rubber material continues to fill. When it reaches the molding space 30, the support device 40 retracts and leaves the molding space 30 until the end surface of the telescopic end 41 of the support device 40 is flush with the surface of the core 11. That is, the support device 40 avoids the entire molding space 30.

[0054] (4) The rubber material continues to fill the entire molding space 30, and the filling is completed;

[0055] (5) Then, the pressure is maintained in the mold closing state, the product is cooled after pressure maintenance, the mold is opened, and the product is demoulded until the product is taken out.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An inverted mold, comprising a moving mold and a fixed mold. The moving mold includes a core and a moving template fixedly connected to the core as a whole. The fixed mold includes a cavity made of steel and a fixed mold base plate fixedly connected to the cavity as a whole. The core and the cavity cooperate to form a molding space. It is characterized in that: The core is an aluminum core, and a supporting device is arranged in the moving mold. The supporting device can expand and contract along the mold opening and closing direction so that its telescopic end can extend into the molding space or retract out of the molding space. When injection molding is carried out using the inverted mold, the following steps are included: (1) The supporting device extends before or at the same time as the mold is closed. (2) Before the rubber material is filled into the molding space after the mold is closed, the supporting device remains extended and its telescopic end abuts against the inner wall of the cavity. (3) The rubber material continues to be filled and reaches the molding space, and the supporting device retracts out of the molding space until the end face of its telescopic end is flush with the surface of the core. (4) The rubber material continues to be filled until the entire molding space is filled, and the filling ends. (5) Hold pressure, cool, open the mold, and demold.

2. The inverted mold according to claim 1, characterized in that: The number of the supporting devices is multiple, and the multiple supporting devices are evenly distributed along the circumferential edge of the molding space.

3. The inverted mold according to claim 1, characterized in that: A through avoidance portion for avoiding the supporting device is formed on the core. The supporting device is fixedly arranged at the moving template, and the telescopic end extends into the molding space or retracts out of the molding space through the through avoidance portion.

4. The inverted mold according to claim 3, characterized in that: When the supporting device retracts out of the molding space, the end face of the telescopic end is flush with the surface of the core and the circumferential side surface of the telescopic end is in sealing fit with the through avoidance portion.

5. The inverted mold according to claim 1, characterized in that: The supporting device includes an oil cylinder and a telescopic component. The oil cylinder is fixedly arranged inside the moving mold, and the telescopic component is fixedly connected to the piston rod of the oil cylinder. The oil cylinder can drive the telescopic component to expand and contract along the mold opening and closing direction.

6. The inverted mold according to claim 1, characterized in that: The moving template is an aluminum plate, and wear-resistant and pressure-resistant inserts are arranged on the moving mold parting surface outside the molding space and surrounding the molding space for at least one week.

7. The inverted mold according to claim 6, characterized in that: The wear-resistant and pressure-resistant inserts are flush with the moving mold parting surface.

8. The inverted mold according to claim 7, characterized in that: The core is a high-strength aluminum core, and the moving template is a high-strength aluminum plate.

9. The inverted mold according to claim 1, characterized in that: An elastic buffer component is covered on the telescopic end.

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