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
1998-12-28
2001-03-20
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
C425S552000
Reexamination Certificate
active
06203310
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to hot runner injection molding and more particularly to such apparatus having an elongated cooled mold core and core lock member with matching abutting parts of their surfaces having a reverse taper.
Circulating cooling fluid through elongated mold cores to reduce cycle time is well known. Molds with long mold cores for making products such as pill vials, cosmetic containers, medical beakers and beverage bottle preforms have a problem known as core shift. As seen in U.S. Pat. No. 5,061,174 to Gellert which issued Oct. 29, 1991, the rear part of the outer surface of the mold core and the abutting surface of the surrounding stripper ring are usually slightly tapered outwardly towards the rear end to facilitate assembly. When the high injection pressure impacts against a number of mold cores in a large mold, it can force the mold cores slightly rearwardly which loosens their tapered seats in the stripper rings and creates space for the mold cores to shift slightly to one side or the other. This lateral shifting of the mold cores results in uneven filling of the cavities and forms a non-concentric product which is unacceptable. This is particularly a problem for bottle preforms, as the blown bottle may sit crookedly or bulge out on one side.
Another problem with elongated cooled mold cores is that the high injection pressure can cause them to flex slightly. Thus, both the core shift and flexing problems limit injection pressure and prevent faster filling and shorter cycle times.
SUMMARY OF THE INVENTION
Accordingly, it is an objection of the present invention to at least partially overcome the disadvantages of the prior art by providing a part of the rear portion of an elongated mold core and the abutting surface of the core lock member with matching reverse tapers.
To this end, in one of its aspects, the invention provides injection molding apparatus having an elongated cavity in a mold and an elongated cooled mold core fitting through an opening having an inner surface in a core lock member attached to a core backing plate. The mold core has a front end, a rear end, an outer surface, a central cooling fluid duct and one or more outer cooling fluid conduit extending longitudinally around the central cooling fluid duct. The outer surface of the mold core has a front portion and a rear portion. The front portion of the outer surface of the mold core forms an inner side of the cavity. A part of the rear portion of the outer surface of the mold core is tapered inwardly towards the rear end of the mold core. The tapered part of the rear portion of the outer surface of the mold core abuts against a matching part of the inner surface of the opening in the core lock member which is also tapered inwardly towards the rear end of the mold core.
Further objects and advantages of the invention will appear from the following description taken together with the accompanying drawings.
REFERENCES:
patent: 2434594 (1948-01-01), Schultz
patent: 4054630 (1977-10-01), Wang
patent: 4151247 (1979-04-01), Hafele
patent: 4289817 (1981-09-01), Valyi
patent: 4332545 (1982-06-01), Cargile
patent: 4571171 (1986-02-01), Blank et al.
patent: 5061174 (1991-10-01), Gellert
patent: 5232718 (1993-08-01), Miyazawa et al.
patent: 5582851 (1996-12-01), Hofstetter et al.
patent: 5688570 (1997-11-01), Ruttinger, Sr.
patent: 5736173 (1998-04-01), Wright et al.
Foley & Lardner
Heitbrink Tim
Mold-Masters Limited
LandOfFree
Injection molding apparatus having mold cores with reverse... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Injection molding apparatus having mold cores with reverse..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Injection molding apparatus having mold cores with reverse... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2458104