Molds for injection molding

Abstract

An injection molding tool for automatically molding plastic articles includes at least two independent mold portions arranged such that they are movable relative to each other along a tool axis between a closed position and an open position, wherein in the closed position they abut against each other along a mold parting plane and in the open position they are spaced apart from each other, and wherein the injection molding tool further includes a first independent mold core having a mounting end and a core end, and wherein each of the two independent mold portions in the closed position includes a cavity that together forms a mold cavity and a socket adapted to hold the mounting end of the first independent mold core in a fixed position between the two mold portions and adapted to release the mounting end in the open position, and wherein the core end of the first independent mold core in the closed position extends from the mounting end along the core axis and extends into the mold cavity in a transverse direction relative to the tool axis, such that the mold cavity forms a tubular space that extends axially along the core axis between the two independent mold portions and the core end of the core portion.

Description

Technical Field

[0001] This invention relates to an injection molding tool for automatically molding plastic articles, the injection molding tool comprising at least two independent mold portions arranged such that they are movable relative to each other along a tool axis between a closed position and an open position, wherein in the closed position they abut against each other along a mold parting plane, and in the open position they are moved away from each other, and wherein the injection molding tool further comprises a first independent mold core having a mounting end and a core end, and wherein each of the two independent mold portions in the closed position comprises a cavity, the cavities together forming a mold cavity and a socket, the socket being adapted to hold the mounting end of the first independent mold core in a fixed position between the two mold portions, and being adapted to release the mounting end when in the open position. Background Technology

[0002] In conventional injection molding tools, a cavity is typically located in one of two mold sections (the cavity section), and a corresponding core is located in the other mold section (the core section). During the molding cycle, as the two mold sections move to the open position of the molding tool, the molded product tends to stick to the core due to friction and shrinkage of the molded plastic material. Therefore, when the product has fully solidified or hardened, it is usually necessary to use one or more ejector pins to detach the product from the core.

[0003] However, in this relationship, it is most necessary to design both the cavity side and the core side of the mold with draft angles to reduce the force required to remove the product from the mold. However, this draft angle can also appear on the molded product and may reduce its functionality.

[0004] This is especially true when injection-molded products include tubular portions (e.g., toy building blocks) and these tubular portions can be connected to each other by frictionally engaging a tubular connecting portion with a correspondingly shaped connecting portion on another building block.

[0005] U.S. Patent No. 2,923,035 discloses an injection molding tool as described in the introduction. In this prior art, a core is arranged in the injection molding tool so that multiple products can be molded onto a set of valves arranged on the core. In a two-step molding process, the core allows the multiple products attached thereto to be easily transferred from one injection molding tool to another. Summary of the Invention

[0006] Based on this, the object of the present invention is to provide an injection molding tool that provides an injection molding scheme, particularly for products including tubular portions, which have reduced draft angles, or even allow the molded product to be removed from the mold without any draft angle. In this context, the term "tubular portion" should be understood as a tube with any cross-section covering any part of the product shape, such as having a circular, square, triangular, rectangular polygonal, elliptical, or other cross-sections, because such tubular shapes are typically molded on a mold core.

[0007] This is achieved by the invention mentioned in the introduction, wherein the core end of the first independent mold core in the closed position extends from the mounting end along the mold core axis and extends into the mold cavity in a transverse direction relative to the tool axis, thereby forming a tubular space that extends axially along the mold core axis between the two independent mold portions and the core ends of the mold core portion.

[0008] Therefore, after the molding cycle, with the injection molding tool in the open position, the first independent mold core and the product attached to the mold core end can be released from between the two mold parts. Subsequently, when the molded product has completely solidified or hardened, the molded product can be released from the first independent mold core.

[0009] In this relationship, the orientation of the core axis is defined by the direction in which the molded product moves out of the core end of the first independent core, and by aligning the core axis transverse to the tool axis, the requirement for draft angles on the core and the cavity can be significantly reduced or even eliminated.

[0010] In a preferred embodiment, the injection molding tool of the present invention further includes a second independent mold core having a mounting end and a core end, and the cavity of each of the two independent mold portions in the closed position further forms a second socket adapted to hold the mounting end of the second independent mold core in a fixed position opposite to the first independent mold core and between the two mold portions, and to release the mounting end in the open position, such that the core end of the second mold core portion in the closed position extends from the mounting end and extends into the mold cavity in a transverse direction relative to the tool axis direction.

[0011] In this relationship, the distal end of the second independent mold core in the closed position, together with the first independent mold core and the two independent mold parts, preferably forms one or more tubular spaces in the mold cavity.

[0012] In another preferred embodiment, the mold cavity also extends prior to the distal end of the core end of the first independent mold core.

[0013] The first independent mold core may also advantageously include a mold ejector pin extending along the mold core axis in the first independent mold core.

[0014] The injection molding tool may advantageously include a plurality of independent mold cavities and a corresponding number of first independent mold cores, each first independent mold core extending into a mold cavity, and wherein the first independent mold cores are interconnected by a first support element.

[0015] In this relationship, the injection molding tool may further include a second independent mold core for each mold cavity, and the second independent mold cores are interconnected by a second support element.

[0016] The first support element and the second support element can be advantageously connected to each other to form a single frame structure, thereby making it easy to remove multiple molded products from the injection molding tool simultaneously.

[0017] In this relationship, at least a portion of the frame structure may preferably extend beyond the two separate mold sections.

[0018] The injection molding tool of the present invention is particularly advantageous for molding toy building blocks, wherein the mold cavity in the closed position forms a substantially closed space, the shape of which is suitable for the injection molding of such toy building blocks including tubular connecting portions, and wherein the mold cavity portion forming the tubular connecting portions extends along the mold core axis of a first independent mold core. Attached Figure Description

[0019] Figure 1 It is shown Figure 3 The diagram shows a schematic cross-section of an embodiment of the injection molding tool of the present invention.

[0020] Figure 2 Is Figure 1 A perspective view of the product molded in the injection molding tool shown.

[0021] Figure 3 yes Figure 1 A partially exploded perspective view of the injection molding tool. Detailed Implementation

[0022] Figure 1 and Figure 3 This invention illustrates a method suitable for injection molding, such as... Figure 2 An example of toy building blocks is shown. In Figure 1 The image shows a cross-section of an injection molding tool in a closed position, wherein molten or fluid plastic material is injected through an injection nozzle 10. Figure 3 The image shows parts of the same injection molding tool in perspective and exploded view.

[0023] The injection molding tool includes two separate mold parts 1 and 2 arranged opposite to each other. The two separate mold parts 1 and 2 are arranged such that they can be used as follows: Figure 1 The closed position shown is similar to... Figure 3 The open positions shown can be moved relative to each other along the tool axis 11. In the closed position, the two independent mold parts 1 and 2 are... Figure 1 The dotted lines 12 in the diagram indicate that the mold parting planes are in contact with each other.

[0024] According to this embodiment of the invention, each of the two independent mold portions 1 and 2 has a cavity 3 forming the outer portion of the mold cavity 6 and an insertion port 7 for receiving the first independent mold core 4 and the second independent mold core 5 in a position such as Figure 1 The two independent mold parts 1 and 2 in the closed position shown are held in a fixed position and are used to release the first mold core 4 and the second mold core 5, as shown. Figure 3 As shown.

[0025] As described above, the two mold parts 1 and 2, along with the first mold core 4 and the second mold core 5, together form the mold cavity 6. In this relationship, each of the first independent mold cores 4 has a mold core end 8 forming the internal space 20 and two independent mold parts 1 and 2, whereby the mold core end 8... Figure 2 Side flanges 21 are formed on the block shown. The first independent mold core 4 and the second independent mold core form an upper side 22 and a spherical protrusion 23 on the block.

[0026] In this relationship, the side flanges 21 thus form the tubular portion of the block, and since these side flanges 21 extend around the core end 8 of the first independent core 4, the block can be removed from the core end 8 at any time after the first independent core 4 is released from between the two independent mold portions 1, 2, as... Figure 3 As shown.

[0027] Therefore, after releasing the first independent mold core 4 and the second independent mold core 5 from between the two separate mold parts 1 and 2, the molded blocks can remain between the first mold core 4 and the second mold core 5. This allows a new set of first and second independent mold cores to be arranged between the two separate mold parts 1 and 2, so that a new molding cycle can be performed even if the previously molded blocks have not yet been removed from the first independent mold core 4 and the second independent mold core 5.

[0028] Since the tubular end of the block formed by flange 21 extends parallel to the core axis 13 of the first independent core 4, it is unnecessary to provide core sections or ejection devices on the two separate mold sections 1 and 2. This provides a solution for removing the molded blocks earlier.

[0029] Furthermore, multiple first independent mold cores 4 and second independent mold cores 5 can be arranged on a common support 9 (e.g., a single frame), thereby enabling them to be moved simultaneously between two independent mold parts 1, 2. This is beneficial for holding the building blocks between the first mold core and the second mold core, for example, for subsequent decoration or two-step molding, or other processing before releasing the molded elements from the mold core 4.

Claims

1. An injection molding tool for automatically molding plastic articles, the injection molding tool comprising at least two independent mold portions arranged such that they are movable relative to each other along a tool axis between a closed position and an open position, wherein in the closed position they abut against each other along a mold parting plane, and in the open position they are spaced apart from each other, and wherein the injection molding tool further comprises a first independent mold core having a mounting end and a core end, and wherein each of the two independent mold portions in the closed position comprises a cavity, the cavities together forming a mold cavity and a socket adapted to hold the mounting end of the first independent mold core in a fixed position between the two mold portions, and in the open position of the injection molding tool, the first independent mold core, together with a product attached to the core end of the first independent mold core, can be released from between the two mold portions, and wherein the core end of the first independent mold core in the closed position extends from the mounting end along the core axis and extends into the mold cavity in a transverse direction relative to the tool axis, such that the mold cavity forms a tubular space extending axially along the core axis between the two independent mold portions and the core ends of the core portions.

2. The injection molding tool of claim 1, further comprising a second independent mold core having a mounting end and a core end, wherein the cavity of each of the two independent mold portions in the closed position further forms a second socket adapted to hold the mounting end of the second independent mold core in a fixed position opposite to the first independent mold core and between the two mold portions, and to release the mounting end in the open position such that the core end of the second mold core component in the closed position extends from the mounting end and extends into the mold cavity in a transverse direction relative to the tool axis.

3. The injection molding tool of claim 2, wherein the distal end of the second independent mold core in the closed position, together with the first independent mold core and the two independent mold portions, forms one or more tubular spaces in the mold cavity.

4. The injection molding tool as claimed in any one of claims 1 to 3, wherein the mold cavity further extends prior to the distal end of the mold core end of the first independent mold core.

5. The injection molding tool according to any one of claims 1 to 3, wherein the first independent mold core includes a mold ejector pin extending along the mold core axis in the first independent mold core.

6. The injection molding tool according to any one of claims 1 to 3, wherein the injection molding tool comprises a plurality of independent mold cavities and a corresponding number of first independent mold cores, each first independent mold core extending into a mold cavity, and wherein the first independent mold cores are interconnected by a first support element.

7. The injection molding tool of claim 6, further comprising a second independent mold core for each mold cavity, wherein the second independent mold cores are interconnected by a second support element.

8. The injection molding tool of claim 7, wherein the first support element and the second support element are interconnected to form a single frame structure.

9. The injection molding tool of claim 8, wherein at least a portion of the frame structure extends beyond the two separate mold portions.

10. The injection molding tool of any one of claims 1 to 3, wherein the mold cavity in the closed position forms a substantially closed space, the shape of which is adapted for injection molding of a toy block including a tubular connecting portion, and wherein the portion of the mold cavity forming the tubular connecting portion extends along the core axis of a first independent mold core.

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