Molds for injection molding

Abstract

An injection molding mold configured to be installed in an injection molding device for automatically molding plastic workpieces, the injection molding mold comprising at least one main runner (9) extending between a gate runner and a runner bifurcation point, the main runner being divided into two or more branch runners leading to a mold cavity at the runner bifurcation point, and the at least one main runner (9) downstream of the gate runner comprising two runners (12), the two runners being joined to each other at a runner confluence point downstream of the gate runner, and wherein the two runners (12) extending to the runner confluence point are straight and extend parallel to each other, and are completely or partially separated by a straight partition wall (13).

Description

Background Art

[0001] The present invention relates to an injection molding mold configured to be installed in an injection molding device for automatically molding plastic workpieces, wherein the injection molding mold includes at least two independent mold parts forming a group of mold cavities, and wherein the independent mold parts include an inlet mold part and a second mold part, wherein the inlet mold part has a mold inlet for injecting liquid plastic from the injection molding device, and wherein the mold part has an abutment side facing a common mold separation plane, and wherein the abutment side forms a group of runners extending between the mold inlet and the mold cavity, and wherein the runner includes two runners, and the two runners are joined to each other at a confluence point at their downstream ends.

[0002] US Patent Application No. 2004 / 0047943 discloses an injection molding mold of the type described above, wherein spaced apart flow channels are arranged at angles intersecting one another to create cross-sectional flows that enhance mixing of materials flowing in the intersecting flow channels. Summary of the invention

[0003] Based on the above, an object of the present invention is to provide an injection molding mold with a cold runner, which allows the cold runner or injection runner to quickly deliver molten material to all mold cavities without increasing the injection pressure or the temperature of the molten material, or without spending a long cooling time to cool the material in the injection runner before demolding.

[0004] In order to achieve the object of the present invention, the present invention proposes that the two flow channels are straight and extend parallel to each other before reaching the merging point, and are completely or partially separated by a straight partition wall.

[0005] According to a preferred embodiment, the mold further comprises a closing mold part, and wherein the second mold part is arranged between the inlet mold part and the closing mold part, and wherein the closing mold part and the second mold part have a second abutment side facing a second common mold separation plane, and wherein the second abutment side forms a mold cavity.

[0006] The two flow channels may have a circular, semicircular, elliptical, semi-elliptical, polygonal or any other shaped cross section in a direction perpendicular to the flow direction in the flow channels, thereby allowing efficient conveyance of the molten material through the flow channels.

[0007] The two parallel flow channels and the optional dividing wall preferably extend from the mold inlet to the runner bifurcation point.

[0008] Furthermore, the partition wall is preferably configured so that the two flow channels are open to each other at the sides thereof closest to each other. Therefore, the demoulding liquid distributing pipe portion is more rigid and easier to demould. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 The schematic diagram shows a perspective view of a liquid distribution pipe or runner in an injection mold;

[0010] Figure 2 , Figure 3 and Figure 4 It is shown Figure 1 Cross-sectional views of different embodiments of cross sections of the main runner are shown. DETAILED DESCRIPTION

[0011] Figure 1 is a schematic diagram showing the principle structure of an injection molding mold 1 having three separate mold parts 2 , 3 , 4 including an inlet mold part 2 , a middle / second mold part 3 and a closing mold part 4 .

[0012] The inlet mold portion 2 has a gate runner 6 extending between the mold inlet 5 and a set of main runners 9, each main runner 9 extends from the gate runner 6 and is connected downstream via a runner bifurcation point 10 to a set of branch runners 11, and the branch runners 11 directly lead to multiple mold cavities (not shown) or lead to multiple mold cavities via multiple additional runner bifurcations and branch runners (not shown).

[0013] In this embodiment, the injection molding mold 1 comprises three mold parts as described above, and the entrance mold part 2 and the intermediate / second mold part 3 have abutting sides forming a mold separation plane 7, at which the runner (cold runner) is formed. The intermediate mold part 3 and the closing mold part 4 also have abutting sides forming a second mold separation plane 8, at which the mold cavity (not shown) forming the molded product is arranged. However, it is obvious to a person skilled in the art that the present invention can also be used in combination with an injection molding mold having only two independent mold parts, namely the entrance mold part 2 and the second mold part 3. In this last-mentioned embodiment, the mold cavity (not shown) is arranged in the same mold separation plane 7 as the runners 9, 11 (cold runners).

[0014] To ensure efficient distribution of molten plastic into the mold cavity, such as Figure 1 The cross section of the main runner 9 shown is larger than the cross section of the branch runner 11 .

[0015] Figure 2 , Figure 3 and Figure 4 Shown perpendicular to Figure 1Different embodiments of the main runner cross section in the flow direction of the molten plastic in the main runner 9 are shown. Each embodiment has two straight runners 12 separated by a straight partition wall 13, so that the molten plastic material flowing through the main runner 9 is generally divided into two independent streams.

[0016] exist Figure 2 , Figure 3 and Figure 4 In the illustrated embodiment, the straight partition wall 13 does not completely separate the two runners 12, so that the runner formed by the main runner 9 is more stable, making it more reliable to demold the runner from the main runner 9. However, it is obvious to those skilled in the art that the straight partition wall can also extend all the way across the cross section of the main runner 9, so that the runner 12 and the runner formed by the main runner 9 are completely separated.

Claims

1. An injection molding mold configured to be installed in an injection molding device for automatically molding a plastic workpiece, the injection molding mold comprising at least two independent mold parts forming a set of mold cavities in its closed position, and wherein the independent mold parts include an inlet mold part and a second mold part, the inlet mold part having a mold inlet and a gate runner for injecting liquid plastic from the injection molding device, and wherein the mold parts have abutment sides facing a common mold separation plane, and wherein the abutment sides form at least one main runner extending between the gate runner and a runner bifurcation point, at which the main runner is divided into two or more branch runners leading to the mold cavity, and wherein the at least one main runner downstream of the gate runner comprises two runners, which are joined to each other at a runner confluence point downstream of the gate runner, and wherein the two runners extending to the runner confluence point are straight and extend parallel to each other and are completely or partially separated by a straight partition wall.

2. The injection molding mold as described in claim 1 further includes a closed mold part, and wherein the second mold part is arranged between the inlet mold part and the closed mold part, and wherein the closed mold part and the second mold part have a second abutment side facing a second common mold separation plane, and wherein the second abutment side forms a mold cavity.

3. The injection molding die of claim 1, wherein the two flow channels both have a cross-section that is at least partially circular, semicircular, semi-elliptical, semi-elliptical or polygonal in a direction perpendicular to the flow direction in the two flow channels.

4. The injection molding die according to claim 2, wherein the two flow channels both have a cross-section that is at least partially circular, semicircular, semi-elliptical, semi-elliptical or polygonal in a direction perpendicular to the flow direction in the two flow channels. 5 . The injection molding die of claim 3 , wherein the two parallel runners extend from a gate runner, and the runner confluence point is formed by the runner divergence point. 6 . The injection molding die of claim 4 , wherein the two parallel runners extend from a gate runner, and the runner confluence point is formed by the runner divergence point. 7 . The injection molding die according to claim 3 , wherein the partition wall is configured such that the two flow channels are open to each other at a side where the two flow channels are closest to each other. 8 . The injection molding die according to claim 4 , wherein the partition wall is configured such that the two flow channels are open to each other at a side where the two flow channels are closest to each other. 9 . The injection molding die according to claim 5 , wherein the partition wall is configured such that the two flow channels are open to each other at a side where the two flow channels are closest to each other. 10 . The injection molding die according to claim 6 , wherein the partition wall is configured such that the two flow channels are open to each other at a side where the two flow channels are closest to each other.

11. An injection molding mold according to any one of the preceding claims, wherein the runner forms a cold runner.

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