Injection mold and method for manufacturing a part

Abstract

The invention relates to an injection mould for producing a part, comprising: a cavity (7) into which a material is injected by a casting (2); a separating member (3) for opening or closing the communication between the cavity (7) and the casting (2), separating the part (1) from the casting (2) in its closed position; and a compartment (4) which is closed when the separator (3) opens the communication between the cavity (7) and the casting (2) and which is open when the separator (3) closes the communication between the cavity (7) and the casting (2), the movement of the separator (3) and the opening and closing of the compartment (4) being synchronized. The invention also relates to a method for manufacturing a part, comprising closing the communication between the cavity (7) and the casting (2), separating the part (1) from the casting (2), and opening the compartment (4) for material while closing the communication between the cavity (7) and the casting (2).

Description

Technical Field

[0001] This invention relates to injection molds and methods for manufacturing parts. Background Technology

[0002] All thermoplastic injection molded parts have a production process in which an injection mold including a cavity plate and a punch plate is formed after appropriate machining to form a mold cavity so that casting or injection can be performed between the machining space of the part to be injected.

[0003] These plates are guided by pillars housed in the cavity plate and bushings in the punch plate, ensuring that the two plates are perfectly aligned each time the mold opens and closes, so as to reproduce new parts with the same size and shape details in each injection cycle.

[0004] In addition, the mold also includes a so-called ejector bridge that is properly aligned with the aforementioned plate, which is properly anchored in the mold and serves as a mechanism for ejecting the injected product.

[0005] All thermoplastic injection molded parts require a material that is melted and prepared, which is provided in a standardized form as small cylinders.

[0006] The manufacturing process involves mounting a mold in an injection molding machine. These machines include a fixed pressure plate on the injection side and a movable pressure plate for ejecting the part. The cavity portion of the mold is mounted on the fixed pressure plate of the machine, while the punch portion is mounted on the movable pressure plate of the machine.

[0007] When the machine is closed, the punch platen connects to the mold cavity platen, thereby ensuring a perfect match in positioning between the two halves of the mold guide and a perfectly uniform match in the machining operations performed in the cavity and the punch, thus forming the shell required to completely fill the cavity with the material to be injected.

[0008] The machine has an injection system suitable for each model, in which the material is deposited in granular form in a hopper that serves as an injection material reservoir, and melted by a properly heated screw conveyor, so that it can be injected into the mold cavity with appropriate melting point and pressure control.

[0009] The cooling circuit circulates through holes machined in the cavity plate and holes machined in the punch plate to accelerate the solidification of the material and ensure its correct consistency when the mold is opened and the produced parts are ejected.

[0010] All injection-molded parts have an opening called a material inlet, which is part of the molding process. Material injected by the machine enters through this opening under pressure. This material inlet must always be cut and manipulated to conceal the mark (which is always part of the product), and in many cases, due to the complexity of the part or its purpose, this mark cannot be visible.

[0011] Therefore, cutting and processing techniques must be performed to reduce or eliminate traces caused by the material entering the mold, which increases the cost of the produced parts. Summary of the Invention

[0012] Therefore, the object of the present invention is to provide an injection mold and method for manufacturing parts, which enables the manufactured parts to have better surface finish at a lower cost than conventional cutting and processing processes.

[0013] The injection mold and method of the present invention overcome the above-mentioned disadvantages and have other advantages that will be described below.

[0014] The injection mold and method according to the invention are described in the respective independent claims, and the dependent claims include optional additional features.

[0015] The injection mold according to the invention includes a cavity into which material is injected by casting, and the material forms a part upon curing.

[0016] In addition, it includes a separator and a compartment, the separator being movable to open or close the communication between the cavity and the casting, separating the part from the casting in its closed position, the compartment closing when the separator opens the communication between the cavity and the casting, and opening when the separator closes the communication between the cavity and the casting, the movement of the separator being synchronized with the opening and closing of the compartment.

[0017] Therefore, cutting or separating the part from the casting while the material is still uncured is done during the manufacturing process itself, eliminating the need for further cutting or cold treatment of the part after it has been cast.

[0018] This disconnection or separation via the separator can be performed throughout the injection cycle, proportional to the filling cycle of the product to be injected, or simply close the material channel as soon as the cavity of the part is filled, as if the separator were a stopcock.

[0019] Since the parts will solidify when the temperature drops, it is important to separate them as quickly as possible.

[0020] The separator remains in the position separating the part from the casting until the required cooling time for the part has elapsed. The part is then ejected in this manner, completely separated from the casting.

[0021] When the machine is shut down again for the next injection cycle, the separator returns to its injection position.

[0022] Therefore, it performs separation or cutting during the injection cycle, relying on actuators to perform separation or cutting in a non-destructive manner, thereby ensuring the quality of its surface finish, which is essential for parts requiring a visually pleasing final appearance. In this way, costly secondary operations on the finished product can be completely eliminated.

[0023] It should be noted that the material in a fluid state behaves similarly to any hydraulic fluid; that is, it is incompressible. Therefore, it is necessary to provide additional volume or space to allow the material deposition introduced by the movement of the separator between the casting and the injected part.

[0024] Without this extra volume, the separator cannot be displaced because the mold is closed. Therefore, the compartment is opened to provide extra volume for the material displaced by the separator.

[0025] The opening movement of the compartment can be operated by any suitable actuator, thereby providing an additional volume to accommodate the displaced material (preferably slightly larger than the volume of the material to be accommodated) to simplify its free containment as much as possible. This is achieved using the same operating principle as the actuator that moves the separator, but in reverse. Attached Figure Description

[0026] To better understand the content already explained above, some accompanying drawings are included, in which actual embodiments are illustrated schematically and by way of non-limiting example only.

[0027] Figure 1 This is a schematic diagram of the injection mold according to the invention during the injection stage; and

[0028] Figure 2 This is a schematic diagram of the injection mold according to the present invention during the separation of the part from the casting. Detailed Implementation

[0029] The purpose of this invention is to manufacture and separate part 1 using only the injection stage.

[0030] The operating principle focuses more on the physical transformation of the material itself, rather than the mechanical means of achieving it.

[0031] For injection, any thermoplastic material involves a sudden change in its own structure, as it changes from a solid to a liquid state in a short period of time, and it is at this melting point that the material must be injected to form a casting.

[0032] Currently, the second operation of casting 2-cutting is typically simplified by using the smallest possible input, even if it means extending the injection cycle. However, this also has certain drawbacks, such as increasing injection pressure and even increasing injection temperature.

[0033] In this respect, the present invention focuses particularly on the opposite: maximizing material input while reducing injection cycles and making injection quality as uniform as possible.

[0034] Thanks to this type of injection, casting 2 can be separated from part 1 because the material's own properties are utilized to fill and seal the mold cavity during the injection stage, eliminating the need for conventional sudden cutting.

[0035] Therefore, when the cavity 7 in the cavity plate 8 of the mold is filled, the separator 3 (preferably located in the convex plate 9) is inserted between the casting 2 and the part 1 like a plug, which allows the separator 3 to separate the casting 2 from the part 1.

[0036] To achieve this, it must be done while the material is in a liquid phase, such as at the precise moment the product is injected. Therefore, the coordination of the movement of different components is crucial.

[0037] These movements can be performed using any type of actuator 5, 6, such as mechanical, hydraulic, or using a suitable geared motor.

[0038] It should be noted that this article focuses on hydraulic systems, although it is obvious that any type of actuator can be used.

[0039] According to the illustrated embodiment, two hydraulic cylinders 5 and 6 are used, which are connected to each other via conduit 10 in the axial region or low-pressure region, acting as interconnected containers. The first hydraulic cylinder 5 is used to advance the separator, while the second hydraulic cylinder 6 is used to open the compartment 4 to accommodate excess material equivalent to the volume of the separator 3; that is, when one hydraulic cylinder rises, the other hydraulic cylinder lowers.

[0040] Compacted material in a fluid state behaves similarly to any hydraulic fluid, i.e., it is incompressible. Therefore, some space must be opened within the compaction chamber 7 to allow the movement of the separator 3 with a certain volume to close the connection between the chamber 7 and the casting 2, i.e., to separate the casting 2 from the part 1.

[0041] If the space is not opened, it will be impossible to insert the separator into the cavity 7 of the mold. Therefore, the aforementioned compartment 4 in the compaction cavity 7 must be opened so that the movable volume can at least accommodate the volume of the separator 3 that separates the casting 2 from the part 1.

[0042] The operation is as follows: Once the mold is closed, the injection stage is performed with the separator 3 in its inactive position and the compartment 4 closed. For this purpose, the first hydraulic cylinder 5 and the second hydraulic cylinder 6 can be coordinated with the injection process. The second hydraulic cylinder 6 operates and closes the compartment 4, while the first hydraulic cylinder 5 uses the same pressure as the second hydraulic cylinder 6 to push the separator 3, located at the end of the casting 2, back.

[0043] In this manner, the channel for injecting material is opened, allowing material from casting 2 to fill cavity 7. As cavity 7 is filled, the first hydraulic cylinder 5 is operated, and this first hydraulic cylinder 5 is the hydraulic cylinder that displaces the separator 3 to finally seal the gap between part 1 and casting 2. Due to the pressure of the first hydraulic cylinder 5, the second hydraulic cylinder 6 opens compartment 4 to accommodate the material that has been displaced by the separator 3.

[0044] Once the cycle is complete, the mold ejects two products, namely part 1 and casting 2 material.

[0045] This invention also brings additional benefits, such as improved surface treatment quality and improved production cycle.

[0046] Regarding the quality of the surface treatment, apart from the sudden cut without pressure, the entire cooling cycle (which defines the final texture) is carried out with the mold fully closed, which will not cause any subsequent damage to the visual surface of the product.

[0047] This invention allows for the use of much larger material inlets, thereby reducing filling cycles and improving cavity filling without overpressure.

[0048] The surface treatment of the product makes it easy to visually locate the injection parts, and this provides visual enhancement for each part.

[0049] Although specific embodiments of the invention have been referenced, it will be apparent to those skilled in the art that the described injection molds and methods are readily subject to many variations and modifications, and that all details mentioned may be replaced by technically equivalent details without departing from the scope of protection defined by the appended claims.

Claims

1. An injection mold for manufacturing parts, comprising: - A cavity plate (8) having a cavity (7) into which the material forming part (1) is injected by casting (2); and The injection mold is characterized in that it further includes: - A separator (3) movable to open or close the communication between the cavity (7) and the casting (2), separating the part (1) from the casting (2) in its closed position; and - The compartment (4) is closed when the separator (3) opens the communication between the cavity (7) and the casting (2), and is open when the separator (3) closes the communication between the cavity (7) and the casting (2). The movement of the separator (3) is synchronized with the opening and closing of the compartment (4).

2. The injection mold according to claim 1, wherein, The separating element (3) is movable by means of the first actuator (5).

3. The injection mold according to any one of the preceding claims, wherein, The opening and closing motion of the compartment (4) is actuated by the second actuator (6).

4. The injection mold according to claims 2 and 3, wherein, The first actuator (5) and the second actuator (6) are synchronized with each other.

5. The injection mold according to claim 4, wherein, The first actuator (5) and the second actuator (6) are hydraulic cylinders.

6. The injection mold according to claim 5, wherein, The hydraulic cylinders (5, 6) are connected to each other by a conduit (10) between two reservoirs that house the shafts of the two hydraulic cylinders (5, 6), such that when one hydraulic cylinder (5) is displaced in one direction, the other hydraulic cylinder (6) is displaced in the opposite direction by the hydraulic pressure caused by the displacement.

7. A method for manufacturing parts, characterized in that, The method includes the following steps: - The material to be formed into part (1) in a fluid state is injected into the cavity (7) of the injection mold through the casting (2); - At the end of the injection, close the connection between the cavity (7) and the casting (2) to separate the part (1) from the casting (2); - While closing the communication between the cavity (7) and the casting (2), open the compartment (4) for the material to accommodate the material that has shifted during the closing step; and - Once the material has cured, eject the manufactured part (1).

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