Glass manufacturing – Plunger
Reexamination Certificate
2000-01-28
2001-09-11
Colaianni, Michael P. (Department: 1731)
Glass manufacturing
Plunger
C065S319000, C065S226000, C065S356000, C065S308000, C425S193000, C425S468000, C425S469000
Reexamination Certificate
active
06286339
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a plunger assembly of the type used in a glass container forming machine of the individual section (I.S.) type when used to produce containers according to the narrow neck press and blow (NNPB) process.
2. Description of the Prior Art
Production of glass containers on an I.S. machine by the NNPB process is generally described in U.S. Pat. No. 5,707,414 (Leidy), which is assigned to the assignee of this application, the disclosure of which is incorporated by reference herein. In conventional NNPB glass container manufacturing, container preforms, which are often called parisons or blanks, are formed from gobs of molten glass in blank molds of an I.S. machine by pressing, by a reciprocating plunger that is powered by a pneumatic cylinder, and this process, conventionally, requires that the plunger and cylinder rod elements of the plunger assembly be separate pieces. These separate pieces conventionally are removably joined to one another by a specially designed threaded fastener that is used to join plunger and cylinder rod clips to one another. Such threaded fasteners, when new, tend to work loose, and, when old, tend to fuse to one another by rusting that occurs in the inherently high temperature environment of a glass container forming machine. Further, a typical plunger is internally air cooled by way of an air inlet pipe that extends into the plunger through the plunger cylinder rod, and this air inlet pipe is subject to breakage in use in the region of the free or distal end of the plunger because of misalignment that can occur in service between the plunger and the plunger cylinder.
The misalignment of the plunger and the air inlet tube contained therein can also lead to contact between the tip of the air inlet tube and the inside of the plunger, and this can lead to an undesirable non-uniform temperature condition on the interior of the plunger.
An alternative glass container forming machine plunger assembly is described in U.S. Pat. No. 3,314,775 (DeShetler et al.), which was assigned to a predecessor of the assignee of the present invention, the disclosure of which is also incorporated by reference herein.
SUMMARY OF THE INVENTION
The aforesaid and other problems associated with prior art pneumatically actuated glass container parison plunger assemblies is overcome by the plunger assembly according to the present invention in which the plunger to cylinder connection permits the plunger to float freely relative to the cylinder rod to which it is removably secured, a factor that reduces plunger cooling tube breakage and helps to maintain plunger surface temperature uniformity; this factor also reduces the time involved in changing a plunger in such a plunger assembly. These results are obtained by connecting the plunger to the cylinder rod by a split locking ring with an inwardly extending flange at an end that engages an outwardly extending flange of the plunger. The split ring is aligned, at its other end, but is not connected to, an endless ring which has an inwardly extending flange that engages an outwardly extending flange of an extension of the cylinder rod, and the cylinder rod extension has an internally threaded free end that is threadably received in the cylinder rod of the plunger assembly. The plunger air inlet tube floats within the plunger, but is maintained in alignment with the extension to the cylinder rod, by the engagement of the plunger by the split ring. The split ring has a series of openings passing therethrough, and these openings are aligned with corresponding openings in the fixed ring. In the normal operating positions of the plunger, the split locking ring is always surrounded by an annular sleeve to keep the locking ring segments from separating; however, to change a plunger, the plunger cylinder is advanced to move the split locking ring to a position external to the annular sleeve, to thereby permit the locking ring segments to be separated, without the need for any-special tool, and thereby remove the plunger from engagement with the cylinder rod. A cooling air seal is formed between the endless ring and the split locking ring thereabove by an O-ring contained in an annular groove of the endless ring, at a location radially inwardly of the openings in the fixed ring and in alignment with an annular surface of the split ring when the segments of the split ring are closed. At this location, the O-ring expands when heated, which increases its sealing effectiveness.
Accordingly, it is an object of the present invention to provide an improved glass container forming machine plunger assembly. More specifically, it is an object of the present invention to provide an assembly of the foregoing character in which a plunger element may be readily disconnected from the cylinder element to which it is connected in service, and without the requirement for any special tool, to facilitate replacement of a plunger.
For a further understanding of the present invention and the objects thereof, attention is directed to the drawing and the following brief description thereof; to the detailed description of the preferred embodiment and to the appended claims.
REFERENCES:
patent: 3314775 (1967-04-01), Shetler et al.
patent: 4033744 (1977-07-01), Davis
patent: 4636240 (1987-01-01), Kozora
patent: 5037465 (1991-08-01), Moore
patent: 5078769 (1992-01-01), Trier
patent: 5120341 (1992-06-01), Nozawa et al.
patent: 5290335 (1994-03-01), Stewart
patent: 5366528 (1994-11-01), Mann
patent: 5531804 (1996-07-01), Vajda
patent: 5707414 (1998-01-01), Leidy
Colaianni Michael P.
Owens-Brockway Glass Container Inc.
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