Plastic article or earthenware shaping or treating: apparatus – Female mold and means to shape parison directly by internal... – Including means to prepare parison
Patent
1998-05-13
2000-04-25
Davis, Robert
Plastic article or earthenware shaping or treating: apparatus
Female mold and means to shape parison directly by internal...
Including means to prepare parison
4254514, 4254515, 425541, B29C 3108, B29C 4956
Patent
active
06053723&
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to improvements made to devices for blow molding or stretch-blow molding containers, especially bottles, from thermoplastic preforms. The device includes a bill-fold type mold having two half-shells joined to each other by a mutual pivoting pin, coinciding with respective edges of the two half-shells, and actuation means associated with the two half-shells in order to pivot the latter with respect to each other in the mold-closing direction or in the mold-opening direction, as well as to container manufacturing plants which make use of such a molding device.
Document FR-A-2,646,802 shows, in its FIG. 4, one arrangement of a bill-fold mold as mentioned above, in which the mold is closed and opened by a reciprocating rotational motion of a driving arm. The said reciprocating rotational motion is described and shown as being conferred by a driveshaft perpendicular to said arm to which it is fastened by fitting onto a square, but no information is provided with regard to the manner in which the driveshaft itself is set into motion.
The object of the present invention is essentially to provide a simple technical solution which can be used to set a mold in motion, such as the one in FIG. 4 of the aforementioned document, and also to provide, because of the simplicity of said means, a complete manufacturing plant constructed around such a single-mold molding device, the half-shells of which can pivot about a fixed pin, which has a simple and reliable design and is capable of maintaining synchronous operation of all its component parts.
Such a single-mold device and fixed pivoting pin are already known from document EP 0,456,866. However, this document does not tackle the problem of synchronizing the opening and closing of the mold with the operation of the other elements of the machine.
SUMMARY OF THE INVENTION
For these purposes, according to a first of its aspects, the invention provides a molding device as mentioned in the preamble, having a single mold and a fixed pivoting pin, which, being arranged in accordance with the invention, is essentially characterized in that the actuation means comprise a movable arm mounted so as to rotate freely about a support pin and fastened to said two half-shells, this arm furthermore supporting a cam follower, or a guide cam capable of engaging with a rotating guide cam, or alternatively a cam follower driven over a circular path, said cam being profiled in such a manner as to cause the arm to move so as to open and close the mold, and drive means for driving the rotating cam, or alternatively the cam follower, said drive means being synchronized with the feeding of the mold with preforms.
Preferably, the pin for supporting the arm is located in a region of the arm lying between its two ends; a first end of the arm is fastened to the two half-shells and a second end of the arm supports the cam follower, or alternatively the cam; in a manner known per se, the actuation means may furthermore comprise two swing links which are articulated, so as to rotate freely by one of their ends, to the abovementioned first end of the arm and are articulated, so as to rotate freely by their other end, respectively to the two half-shells on each side of the mutual pivoting pin of the latter.
In a preferred embodiment, the cam follower is borne by the arm and the rotating cam is provided in or supported by a rotating plate.
In order to construct a device which has both a reliable operation and a simple structure, provision is preferably made for the cam to be configured in order to engage with the cam follower at least from the start of mold opening until at least the end of mold closing, and auxiliary locking means, which are independent of the aforementioned actuation means, are provided in order to keep the mold locked during molding from the end of mold closing until the start of mold opening; advantageously, then, the cam extends along an open section and no longer engages with the cam follower between at least the end of mol
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Grouas Jean-Fran.cedilla.ois
Guiffant Alain
Davis Robert
Sidel
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