Glass manufacturing – Processes – With measuring – sensing – inspecting – indicating – or testing
Reexamination Certificate
2001-03-08
2004-03-02
Vincent, Sean (Department: 1731)
Glass manufacturing
Processes
With measuring, sensing, inspecting, indicating, or testing
C065S076000, C065S079000, C065S158000, C065S160000, C065S229000, C065S362000
Reexamination Certificate
active
06698241
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a method and apparatus for producing a parison by means of a pressing process in a parison mold of a press-blow glass forming machine.
In the case of a known apparatus of this type (U.S. Pat. No. 4,336,050 A) the loading orifice is located at the top in a block mold which is not longitudinally divided. A longitudinally-divided parison mold middle piece is disposed between the block mold and the neck mold. The neck mold comprises a longitudinally-divided neck tool and a guide ring, which is not longitudinally-divided and is held in a radial groove of the neck tool, for the pressing plunger. The end operating position of the pressing plunger is defined by virtue of the fact that an upper annular surface of a pressing plunger holder moves into position against an annular counter surface of the guide ring. Owing to the axial play, which increases as the wear increases, between the guide ring and the closed neck tool the end operating position changes in an undesired manner. The axial outer sealing edge of the neck is obviously formed by the opposite radial end face of the guide ring. This leads to undesired sharp-edged glass seams, which are pressed into the mold gaps at the transition from the radially extending, axially outer sealing edge to the adjacent radially inner and radially outer neck contour. These glass seams also impair the sealing effect between the neck and its closure device.
With respect to the prior art, FIGS. 1 and 2 of U.S. Pat. No. 4,662,928 A disclose a forming tool of a blow-blow machine known per se for producing champagne bottles. It comprises a longitudinally-divided parison mold and a longitudinally-divided neck tool. An axially moveable plunger lies in its axial end operating position against the closed neck tool. The plunger forms a small, radially inner part of the axially outer sealing edge of the neck of the champagne bottle. The remaining part of the sealing edge is formed by the neck tool. An annular glass seam is pressed between these two sealing edge parts into the parting line between the plunger and the neck tool (FIGS.
2
and
3
A). Moreover, opposite perpendicular glass seams, which originate from the juncture plane of the neck tool, extend as far as into the sealing edge. These glass seams must be subsequently removed in a costly procedure by “fire polishing” (FIG.
3
B). In order to avoid these disadvantages U.S. Pat. No. 4,662,928A proposes to allow the entire sealing edge to be formed by a guide ring which is not divided and which is held in the neck tool (
FIGS. 4
to
6
). However, this then causes similar disadvantages to those experienced in U.S. Pat. No. 4,336,050A.
In the case of apparatus known per se (
FIG. 1
or EP 0 327 240 A1) the end operating position of the pressing plunger is determined exclusively by the deforming resistance of the molten glass when the cavity is completely filled with glass and the parison has been completely pressed. Thus, the end operating position of the pressing plunger depends upon the respective mass of the gob and/or of the respective volume of the cavity. The pressing plunger comprises on its foot a slightly conical, almost cylindrical guide section. The slight conical shape is intended to facilitate the subsequent removal of the pressing plunger from the parison. On a final part of the path of the pressing plunger as far as into its end operating position the guide section is received into a guide ring, which is not longitudinally divided, and as a result is centered in the radial direction and guided. Owing to the slight conical shape of the guide section a radial gap, whose width depends upon the respective end operating position of the pressing plunger, remains between the guide section and the guide ring. During the pressing process it is possible in certain operating situations for the glass mass to penetrate into this gap in an undesired manner. The guide ring is held radially outside in a holding groove of the neck tool. The guide ring comprises on its end facing the cavity a forming ring for forming the axially outer sealing edge of the neck of the parison.
It is known per se from U.S. Pat. No. 4,411,681 A to raise a plunger first into its end operating position in which a ring of the plunger lies against an undivided guide ring of a neck mold (
FIGS. 1
to
3
). A glass gob then falls into a filling orifice of a mold cavity of a longitudinally- and transversely-divided parison mold and onto the tip of the plunger. A blow head is introduced from the top into the filling orifice (
FIG. 2
) and blows the glass gob firmly into the parison mold and the neck mold and around the plunger, wherein a space is existing between the blow head and the glass (FIG.
3
). The plunger is subsequently lowered into a middle position (FIG.
4
). Compressed air is introduced through the neck and preliminarily blows the parison until it also contacts the blow head. Finally, the finished parison is removed from the parison mold (FIG.
5
). This combined process of settle and preliminarily blowing the parison whilst using the plunger requires an expensive construction and a comparatively long cycle. Moreover, it is disadvantageous that a sealing edge of the neck of the parison is formed by means of the guide ring.
It is known per se from U.S. Pat. No. 4,411,681 A to raise a plunger first into its end operating position in which a ring of the plunger lies against an undivided guide ring of a neck mold (
FIGS. 1
to
3
). A glass gob then falls into a filling orifice of a mold cavity of a longitudinally- and transversely-divided parison mold and onto the tip of the plunger. A blow head is introduced from the top into the filling orifice (
FIG. 2
) and blows the glass gob firmly into the parison mold and the neck mold and around the plunger, wherein a space is existing between the blow head and the glass (FIG.
3
). The plunger is subsequently lowered into a middle position (FIG.
4
). Compressed air is introduced through the neck and preliminarily blows the parison until it also contacts the blow head. Finally, the finished parison is removed from the parison mold (FIG.
5
). This combined process of settle and preliminarily blowing the parison whilst using the plunger requires an expensive construction and a comparatively long cycle. Moreover, it is disadvantageous that a sealing edge of the neck of the parison is formed by means of the guide ring.
It is known per se from DE 32 32 288 C1 to introduce the glass gob into a block mold cavity. The volume of the block mold cavity is first enlarged by an additional volume. This can occur by moving a piston downwards in a base cavity of the block mold. The additional volume is nullified again by virtue of the upwards movement of the piston until the parison has been formed.
Apparatus for adjusting the mass of the glass gob on a feeder device is known per se from GB 2 178 421 A.
SUMMARY OF THE INVENTION
The object of the invention is to improve the manner in which the neck of the parison is formed.
This object is achieved with respect to the method by virtue of a method for producing a parison in a parison mold, wherein the parison has a neck, a base and an axially outer sealing edge of the neck. The parison mold has a cavity and a neck mold, the neck mold having a through passage and a neck tool which forms the neck of the parison, and wherein the neck tool has a stop surface. The method includes the following steps: (a) introducing a gob of molten glass into the cavity of the parison mold; (b) pressing a pressing plunger into the gob through the through passage until the pressing plunger reaches an end operating position defined by the stop surface to preliminarily press the parison; and (c) simultaneously with or following step (b), exerting pressure on the base of the parison with a pressing element, which defines part of the cavity, until the cavity is completely filled with the molten glass and the parison is finished-pressed, wherein the axially outer sealing edge of the neck is completely formed by the press
Hermann Heye
Synnestvedt & Lechner LLP
Vincent Sean
LandOfFree
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