Sealing member in an injection molding machine

Details Sealing member in an injection molding machine Sealing member in an injection molding machine

2001-07-24

2003-05-13

Heitbrink, Tim (Department: 1722)

Plastic article or earthenware shaping or treating: apparatus

Female mold and charger to supply fluent stock under...

With coupling between charger and mold

C264S328800

Reexamination Certificate

active

06561790

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to injection molding machines and more particularly relates to a sealing member inserted in an injection molding machine for substantial reduction or elimination of leakage of a molten material.
2. Summary of the Prior Art
Hot runner assemblies are previously known and are used for molds having a plurality of mold cavities for injection molding of articles of relatively large surface dimensions. The advantage of hot runner molds is that the material is maintained in the molten state in the channels during the interval between each injection operation and the following one.
Prior art hot runner molds may be divided into two groups, i.e. hot runner manifolds that are one piece and have all the melt channels formed therein and multi-piece manifolds that are connected together with “bridge” manifolds. In the multi-piece arrangement, a “bridge” manifold connects at least two sub-manifolds. Melt channels in the bridge manifold align with melt channels in the sub-manifolds. Typically, the bridge manifold is connected to a supply of pressurized molten material.
The melt channels in the “bridge” manifold must align with the melt channels in the sub-manifolds when they are at a predetermined elevated temperature. The sub-manifolds typically communicate with at least one injection nozzle for the transfer of the molten material to a mold cavity. Due to thermal expansion during heat up of the various hot runner manifolds, relative motion between the “bridge” manifold and the sub-manifolds will occur. In accordance with the prior art, the flat surface of the sub-manifold will rub across the flat surface of the “bridge” manifold during heat up, and when the desired temperature is reached, the interface between the respective melt channels will align and seal off by virtue of compressive forces that build up during the heat up process. The reliability and repeatability of this seal off has proven to be problematic and leakage of the molten material between the “bridge” manifold and the sub-manifold is a recurrent problem.
Therefore there is a need for an improved hot runner system that increases the reliability and repeatability of the seal between separate manifold melt channels.
SUMMARY OF THE INVENTION
The primary objective of the present invention is to provide a means for reliably sealing the melt channel interface between a bridge manifold and a sub-manifold.
Another object of the present invention is to reduce the compressive forces generated in a hot runner subsystem during heat up thereby allowing the use of fewer fasteners.
Yet another object of the present invention is to reduce or eliminate the occurrence of galling and/or fretting between plates as they move during heat up.
The foregoing objects are achieved by providing a sealing member or compression disk at the interface of the melt channels between the two manifolds. The sealing member preferably has at least one non-flat surface for concentrating the sealing pressure adjacent the melt channels thereby reducing the forces required to create a reliable seal therebetween.
Further objects and advantages of the present invention will appear hereinbelow.


REFERENCES:
patent: 3533594 (1970-10-01), Segmuller
patent: 3812228 (1974-05-01), Skoroszewski
patent: 3940224 (1976-02-01), Armour
patent: 4219323 (1980-08-01), Bright et al.
patent: 5232710 (1993-08-01), Miyazawa et al.
patent: 5896640 (1999-04-01), Lazinski et al.
patent: 6062846 (2000-05-01), Kalemba
patent: 6203305 (2001-03-01), Hofstetter et al.
patent: 28 05 863 (1979-08-01), None
patent: 0 480 223 (1992-04-01), None
patent: 0 911 133 (1999-04-01), None
patent: WO 97 47458 (1997-12-01), None
Kunststoffe Magazine Article “Angussloses Spritzgiessen mit Heisskanalsystemen” (1979) Figure 14 on p. 780 with partial translation provided.
ANTEC 1987 “The Standardization and Modularization of Hot Runner Systems” by Kopinski pp 1175-1182.
Kunststoffe Magazine (1985) “Development and design of Injection Moulds” by Bangert and Leverkusen pp. 542-549 with translation attached.

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