Molding tool for injection molding

Abstract

An injection molding tool comprising at least two separate mold parts arranged such that they are movable along a central tool axis A between a closed position and an open position. At least one of the mold parts includes an alignment compensator having a first compensator part and a second compensator part. The first compensator part has a slot adapted to receive the second compensator part such that the second compensator part is slidable in the slot along the central tool axis and is allowed to tilt in the slot. A seal is arranged such that the seal and the first and second compensator parts enclose a space in the slot containing an elastic and / or fluid material, and the seal includes a lid made of plastic material arranged between the second compensator part and the liquid-filled space in the slot.

Description

Technical Field

[0001] The present invention relates to an injection molding tool for automatically molding plastic articles, the injection molding tool comprising at least two separate mold parts, the mold parts being arranged such that they are movable along a central tool axis between a closed position in which they are adjacent to each other and an open position in which they are remote from each other, and wherein at least one of the mold parts comprises at least one alignment compensator, each alignment compensator comprising a first compensator part and at least one second compensator part, the first compensator part having one or more slots, each slot being adapted to receive each second compensator part such that it can slide in the slot along the central tool axis and allowing the second compensator part to tilt in the slot, and wherein a seal is arranged such that the seal and the first compensator part and the second compensator part enclose a space in the slot containing an elastic or fluid-like material. Background Art

[0002] Various embodiments of molding tools have been disclosed in the prior art, the purpose of which is to compensate for misalignment of tool parts, which misalignment may, for example, lead to mold wear or even molded product wear.

[0003] An example of such a molding tool is disclosed in U.S. Patent No. 4,372,740, which discloses a tool for injection molding, the tool comprising a core, wherein two or more cores are each arranged in a slot so as to enclose a space behind each core. Each space is filled with a fluid substance and is provided with one or more flow channels for the fluid substance to allow fluid to flow from one space to another, thereby compensating for, for example, cores having different heights. In addition, the cores of this prior art can tilt in the slot, thereby enabling angular alignment of the cores. Summary of the Invention

[0004] On this basis, the object of the present invention is to provide an injection molding tool of the type described in the introduction, in which alignment of the mold parts is achieved in a simple manner.

[0005] This is achieved by the present invention as mentioned in the introduction, wherein the seal comprises a cover made of plastic material and is arranged between the second compensator part and the space in the slot filled with an elastic or fluid material.

[0006] Thereby, regardless of how the second compensator part tilts relative to the first compensator part, the seal, being a single and easily producible part, provides an efficient barrier against leakage of the material in the space within the slot.

[0007] According to a preferred embodiment, the seal is formed as a plate with an outer perimeter such that it fits snugly or by press fit into the slot and forms a tight seal along its entire perimeter.

[0008] The seal is preferably made of polytetrafluoroethylene (PTFE).

[0009] Each space may preferably be completely enclosed within the slot, but in an alternative embodiment, two or more slots may be connected by at least one channel to allow some fluid or elastic material to flow through the channel from one slot to another.

[0010] The elastic or fluid material in the space may be selected from any material capable of flowing under pressure and providing substantial hydrostatic pressure within the space of the slot. Examples of such materials may be viscoelastic materials (such as putty) or materials with high viscosity (such as asphalt). However, the material preferably may include semi - liquid or semi - solid materials that can harden or not harden, and, in a preferred embodiment, the elastic material is a highly incompressible silicone - based material.

[0011] The injection molding tool may include at least two independent alignment compensators, where one alignment compensator includes a first compensator part and a second compensator part, and the other alignment compensator includes two or more second compensator parts that are arranged in a plane perpendicular to the central tool axis and in a pattern around the central tool axis. For example, this embodiment allows the alignment compensators to cooperate to compensate for angular misalignment and height variations of the core arranged within the injection molding tool.

[0012] In this relationship, each of the two or more second compensator parts preferably may form a mold core, each mold core having a part of the mold cavity arranged on the side facing away from the slot. Description of the Drawings

[0013] In the drawings:

[0014] Figure 1 is a schematic view showing a part of the injection molding tool of the present invention in a first position before assembly.

[0015] Figure 2 is a schematic view showing the Figure 1 injection molding tool in a second assembled working position. Detailed Description

[0016] Figure 1 and 2It is a schematic diagram showing cross-sections of a part of the same embodiment of the injection molding tool of the present invention at two different positions, which will be explained in more detail below.

[0017] The injection molding tool is very complex, and since it is readily apparent to those skilled in the art that the present invention can be applied to many different embodiments of injection molding tools, the schematic diagram only shows the main parts of the injection molding tool. In addition, only the details of the injection molding tool necessary to illustrate the principles of the present invention are shown.

[0018] This embodiment of the injection molding tool has a movable substrate 1, which is adapted (not shown) to be attached to the sliding support structure of an injection molding machine (not shown) for opening and closing the mold. A fixed substrate 10 is attached to the fixed part of the support structure of the injection molding machine and has a sprue 11 and a runner 12, which are arranged to receive, for example, molten plastic material from a plasticizing screw and guide the molten plastic material to a set of mold cavities, each of which is arranged at a core 14, and the core 14 is firmly mounted on the fixed substrate 10 on the side facing away from the fixed substrate.

[0019] A first alignment compensator is fastened to the movable substrate 1, which is fixed to the movable part (not shown) of the injection molding machine along the central tool axis A.

[0020] The first alignment compensator includes a first compensator member 2, which has a slot 3 provided on the side facing away from the substrate. The slot 3 has an opening in the direction away from the substrate 1, and a second compensator member 4 is slidably and tiltably arranged in the open end of the slot 3. At the closed bottom of the slot 3, fluid is enclosed in a space 5, and a plate separating the second compensator member 4 from the space 5 filled with fluid is arranged. The plate forms a seal 6 and is tightly or press-fitted into the side wall of the slot 3 along its entire periphery, so that the fluid is completely enclosed in the space 5.

[0021] Another alignment compensator is arranged in a separate part of the injection molding tool. The alignment compensator includes a first compensator member and two second compensator members 4' and 4". The first compensator member has two slots 3' and 3" arranged on the same side of the first compensator member. Both the slots 3' and 3" have openings, and the second compensator members 4' and 4" are slidably and tiltably arranged in the open ends of each of the slots 3' and 3".

[0022] At the closed bottom of each of the slots 3' and 3", fluid is enclosed in spaces 5' and 5", and plates are arranged for separating each of the second compensator members 4' and 4" from the spaces 5' and 5" filled with fluid. Each plate forms seals 5' and 5", and fits tightly or by press fit along their entire perimeter into the side walls of the slots 3' and 3", so that the fluid is completely enclosed in the spaces 5' and 5".

[0023] In this embodiment, the two second compensator members 4' and 4" both constitute cores, each core having a part of a cavity arranged on the side facing away from the slots 3' and 3", so that together with the core 14 mounted on the fixed substrate 10 they form a complete cavity.

[0024] However, those skilled in the art should be clear that the second compensator members may constitute other components of the injection mold.

[0025] In a preferred embodiment, the fluid enclosed in the spaces 5, 5' and 5" may be a silicon-based material that can harden or cannot harden and has very low compressibility, and the seals 6, 6' and 6" are preferably made of plastic material plates, such as PTFE plates.

[0026] Thus, the injection molding tool includes a movable part, a movable substrate 1 is fixed to the movable support structure of an injection molding machine (not shown), and a first alignment compensator is fixed to the movable substrate. In this embodiment, another alignment compensator including the cores 4', 4" is an interchangeable unit, which can be releasably attached to the first alignment compensator, so that the cavity can be easily replaced without removing the first alignment compensator from the movable substrate 1.

[0027] Therefore, Figure 1 shows the injection molding tool in a position before assembly, while Figure 2 shows the same injection molding tool in a fully assembled position after at least one production cycle.

[0028] In Figure 1 all components are symmetrically arranged about the central axis A of the injection molding tool.

[0029] When the two separate mold parts are moved together to close and open the mold to Figure 2When in the position shown, due to the compressive forces exerted by the second compensator members 4, 4' and 4", the fluid enclosed in the spaces 5, 5' and 5" is redistributed. The seals 6, 6' and 6" and the second compensator members 4, 4' and 4" tilt until a hydrostatic pressure is generated in the fluid in the spaces 5, 5' and 5", such that the two alignment compensators can compensate for the angular misalignment and varying height of the tool members.

[0030] In this open position of the injection molding tool, the mold members are held in alignment by the frictional forces between the seals 6, 6' and 6", which fit tightly or are press-fitted into the slots 3, 3' and 3", or the fluid enclosed in the slots 3, 3' and 3" can be a viscoelastic fluid or even be hardened to maintain the relative positions of the components of the injection molding tool.

Claims

1. An injection molding tool configured to automatically mold plastic articles, the injection molding tool comprising at least two separate mold parts, the mold parts being arranged such that they are movable along a central tool axis between a closed position in which they are adjacent to each other and an open position in which they are spaced apart from each other, and wherein at least one of the mold parts comprises at least two separate alignment compensators, one of the alignment compensators comprising a first compensator part and at least one second compensator part, the first compensator part having one or more slots, each slot being adapted to receive each second compensator part such that it can slide in the slot along the central tool axis and allowing the second compensator part to tilt in the slot, and wherein a seal is arranged such that the seal and the first compensator part and the second compensator part enclose a space in the slot containing an elastic and / or fluid material, and wherein the seal comprises a cap made of plastic material and is arranged between the second compensator part and the space in the slot; Wherein, the other alignment compensator comprises two or more second compensator parts, each of the two or more second compensator parts being a core, each core having a part of a mold cavity arranged on a side facing away from the slot.

2. The injection molding tool according to claim 1, wherein the seal is a plate having an outer perimeter such that it fits tightly or by press fit into the slot and forms a tight seal.

3. The injection molding tool according to claim 1, wherein the seal is made of polytetrafluoroethylene (PTFE).

4. The injection molding tool according to claim 1, 2 or 3, wherein the space is completely enclosed in the slot.

5. The injection molding tool according to claim 1, 2 or 3, wherein the elastic or fluid material in the space is a semi - liquid or semi - solid material.

6. The injection molding tool according to claim 1, 2 or 3, wherein the elastic material is a viscoelastic material.

7. The injection molding tool according to claim 6, wherein the elastic material is putty or asphalt.

8. The injection molding tool according to claim 5, wherein the elastic material is a silicone resin material.

9. The injection molding tool according to claim 6, wherein the elastic material is a silicone resin material.

10. The injection molding tool according to claim 7, wherein the elastic material is a silicone resin material.

11. The injection molding tool according to claim 1, 2 or 3, the second compensator parts being arranged in a plane perpendicular to the central tool axis and in a pattern around the central tool axis.

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