Plastic article or earthenware shaping or treating: apparatus – Female mold and charger to supply fluent stock under... – With means to heat or cool
Reexamination Certificate
1999-02-24
2001-10-16
Heitbrink, Tim (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Female mold and charger to supply fluent stock under...
With means to heat or cool
C425S562000, C425S564000
Reexamination Certificate
active
06302680
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to hot runner injection molding and more particularly to injection molding apparatus having a removable nozzle seal which screws onto the outside of the front end of the heated nozzle.
Nozzle seals bridging the insulative air space between the heated nozzle and the surrounding cooled mold are well known. U.S. Pat. No. 4,793,795 to Schmidt et al. which issued Dec. 27, 1988 shows a gate insert which screws into place and U.S. Pat. No. 5,028,227 to Gellert et al. which issued Jul. 2, 1991 shows a gate insert which slides into place. U.S. Pat. No. 5,299,928 to Gellert which issued Apr. 5, 1994 shows a two-piece nozzle seal which screws into place. U.S. Pat. No. 5,849,343 to Gellert et al. which issued Dec. 15, 1998 shows another type of gate insert which screws into place. While these previous nozzle seals and gate inserts are suitable for many applications, they all have the disadvantage that they are seated in an opening on the inside of the nozzle. This limits the size of any insert or liner seated in the front end of the nozzle which, in turn, restricts the strength and thermal conductivity from the heating element to the gate. The ones that screw in have the further disadvantage that location of the front end of the nozzle is not accurate enough for some applications.
It is also known to provide a sealing ring extending around the outside of the nozzle. For instance, U.S. Pat. No. 5,795,599 to Gellert which issued Aug. 18, 1998 shows a nozzle guide and sealing ring mounted around the outside of the front end of the nozzle.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to at least partially overcome the disadvantages of the prior art by providing a removable nozzle seal which screws onto the outside of the front end of a heated nozzle.
To this end, in one of its aspects, the invention provides an injection molding apparatus having one or more heated nozzles extending forwardly into a well in a cooled mold in alignment with a gate leading to a cavity. There is an insulative air space extending between the heated nozzle and the surrounding cooled mold. The heated nozzle has a rear end, a front end, and a portion adjacent the front end with a generally cylindrical outer surface. It has a melt bore extending forwardly therethrough from the rear end and an insert extending forwardly from a recessed seat in the front end of the at least one heated nozzle. The insert has a rear end and a melt bore extending forwardly therethrough from an inlet at the rear end aligned with the melt bore through the nozzle. A mounting sleeve is integrally mounted around the cylindrical outer surface of the portion adjacent the front end of the heated nozzle and the mounting sleeve has a threaded outer surface. A hollow removable nozzle seal has a central portion, a retaining portion extending rearwardly from the central portion, and a sealing and alignment flange portion extending forwardly from the central portion. The retaining rear portion has a threaded inner surface to removably screw onto the threaded outer surface of the mounting sleeve. The forwardly extending sealing and alignment flange portion fits into a cylindrical portion of the well in the mold extending adjacent the gate to align the front end of the heated nozzle with the gate and prevent leakage of melt into the insulative air space between the heated nozzle and the surrounding cooled mold.
In another of its aspects, the invention provides injection molding apparatus having one or more heated nozzles extending forwardly into an opening in a cooled mold extending to a cavity. There is an insulative air space extending between the heated nozzle and the surrounding cooled mold. The heated nozzle has a rear end, a front end, a portion adjacent the front end with a generally cylindrical outer surface. It has a melt bore extending forwardly therethrough from the rear end. A mounting sleeve is integrally mounted around the cylindrical outer surface of the portion adjacent the front end of the heated nozzle. The mounting sleeve has a threaded outer surface. A removable nozzle seal has a front end, a central portion, a hollow retaining portion, extending rearwardly from the central portion, and a sealing and locating portion extending forwardly from the central portion. The central portion and the forwardly extending sealing and locating portion has a melt bore extending therethrough in alignment with the melt bore in the heated nozzle and leading to a gate at the front end of the nozzle seal. The retaining rear portion has a threaded inner surface to removably screw onto the threaded outer surface of the mounting sleeve. The forwardly extending sealing and locating portion fits into a cylindrical portion of the opening in the mold extending to the cavity to locate the front end of the heated nozzle and prevent leakage of melt into the insulative air space between the heated nozzle and the surrounding cooled mold.
Further objects and advantages of the invention will appear from the following description taken together with the accompanying drawings.
REFERENCES:
patent: 3935972 (1976-02-01), Tsunemoto et al.
patent: 4010903 (1977-03-01), Sakuri et al.
patent: 4266723 (1981-05-01), Osuna-Diaz
patent: 4793795 (1988-12-01), Schmidt et al.
patent: 5028227 (1991-07-01), Gellert et al.
patent: 5208052 (1993-05-01), Schmidt et al.
patent: 5299928 (1994-04-01), Gellert
patent: 5795599 (1998-08-01), Gellert
patent: 5849343 (1998-12-01), Gellert et al.
patent: 5871786 (1999-02-01), Hume et al.
patent: 5879727 (1999-03-01), Puri
patent: 5895669 (1999-04-01), Seres, Jr. et al.
patent: 6009616 (2000-01-01), Gellert
patent: 0 854 027 (1998-07-01), None
patent: 8 004 819 (1982-04-01), None
Gellert Jobst Ulrich
Nakanishi Itsuto
Foley & Lardner
Heitbrink Tim
Mold-Masters Limited
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