Transfer device for parisons and finished products in injection blow molding devices

A transfer device for open neck plastic parisons and finished articles in injection blow molding equipment. The device includes a core or pin which is attached to a plate and can be inserted into the parison or finished article. A collet is included which is supported by the core, an extension of the core, or the plate in such a way that the collet grips the neck of the parison or finished article when in one position, and releases it when in a second position.

BACKGROUND OF THE INVENTION 
Methods and procedures are already known, or have been proposed, for the 
manufacture of organic plastic parisons and finished articles via 
injection molding, whereby the parisons and finished articles exhibit 
bi-axial orientation, produced, for example, by stretching and blowing the 
parisons. 
It is also known that the process requires transference of the parison from 
the injection core to a tempering mold, from the tempering mold to a 
stretch/blow mold, and from this to a position where the finished plastic 
hollow body, i.e., the stretched and blown parison, may be ejected. Of 
course, not all of these transfer operations may be necessary. Where they 
are required however, the present invention represents an improvement in 
conventional procedure. 
For a better understanding of the present invention, it should be noted 
that the neck of the article under production, also referred to 
synonymously as the "edge" or "finish", is of great importance in carrying 
out any of the above-mentioned transfer operations with the desired 
accuracy. It must maintain its shape without distortion during each 
operation, and in particular, it always should remain concentric with the 
body of the parison. 
The aim of the present invention is to protect the neck, and to prevent any 
distortion from occurring during the operations of transferring the 
parison from the mold in which it is first produced, for example by 
pressure molding, and accurately inserting it in any subsequent mold 
during the production sequence. 
A further aim of the invention is to provide a seal sufficiently strong to 
permit application of relatively high internal pressure to the parison 
during the blowing stage, without the neck losing its shape. 
SUMMARY OF THE INVENTION 
In accordance with the present invention the objects and advantages of the 
present invention are readily obtained. The transfer device of the present 
invention for open neck plastic parisons and finished articles in 
injection blow molding equipment comprises: a core or pin which is 
attached to a plate and is operative for insertion into said parison or 
finished article, said device including a collet movable between a first 
position and a second position supported by an element selected from the 
group consisting of said core, an extension of the core, and the plate, so 
that said collet grips the neck when in one of said positions, and 
releases it when in a second of said positions. Preferably, the collet 
slides between its supports from said first to said second position.

DETAILED DESCRIPTION 
FIG. 1 shows a parison 16, which has been transferred to a tempering mold 
22 (the first mold), by means of an injection core 15. In the next step, a 
stretch/blow core 30 (the second core) is inserted into the parison. The 
parison then is transferred to a finishing mold 23 (the second mold) by 
means of the second core. The finished article finally is transferred from 
the second mold 23 to the ejector position by means of an injector plug 
41. The details of the foregoing are not necessary to an understanding of 
the present invention and are described in more detail in U.S. Pat. No. 
4,174,934, the disclosure of which is incorporated herein by reference. 
FIG. 2 illustrates those components of the device of the present invention 
which are specifically relevant to the present invention. On the left, the 
components are shown in the open position, on the right, in the closed 
position. The parison 29 is inserted into the tempering mold 22 (FIG. 2). 
The parison neck 29a is fully formed by injection molding in the 
corresponding neck mold, with no further operations being required thereon 
when the parison neck is removed from the neck mold. 
Because the parison neck 29a is usually relatively large and bulky, it is 
slow to cool to a temperature at which it can resist external pressure 
without distortion. 
The blow core 30, shown in FIG. 1, is inserted into the parison 29 while 
the parison is in the tempering mold 22. After being subjected to 
temperature conditioning in the mold 22, the parison 29 is removed from 
mold 22 by means of the core 30. It is clear that appreciable force must 
be exerted when inserting the core 30 into the parison neck 29a, if it is 
to fit sufficiently tightly. In order to resist this pressure without 
distortion, the neck 29a must be allowed to cool to the requisite 
temperature prior to insertion of the core 30. Since a relatively lengthy 
cooling-off period would be required, the operating cycle would be 
considerably extended. However, the device in accordance with the present 
invention makes possible an alternative and advantageous procedure, 
whereby the insertion of the core 30, and the transfer of the parison from 
the mold 22 to the next operating position may be carried out without 
delay and without making allowance for the mechanical resistance of the 
parison neck 29a. 
The device shown in FIG. 2 consists of 2 plates, 31a and 31b, corresponding 
to plate 31 (FIG. 1), to which a flanged sleeve 133 is attached. The 
flanged sleeve 133 encloses an extension piece 32 of the core 30 which can 
be considered part of said core. A collet 134 is inserted in the narrow 
space between the plates 31a and 31b, and the flanged sleeve 133, in such 
a way that it is supported by the core, or the core extension or the 
plates and is capable of reciprocating motion within this space. Collet 
134 carries quills 135 which extend axially and are arranged in a 
cylindrical or circular pattern on the collet 134. The quills 135 have 
enlarged heads 136 which form an inner contour capable of gripping or 
enclosing the parison neck 29a. The quills 135 are elastic or flexible so 
that when pressed inward they form a closed surface. If no pressure is 
applied to the quills, however, they remain spaced equidistantly from one 
another, the spaces tangentially directed. The dimensions of the upper 
part of the collet 134 in particular, are such that it can slide snugly 
between the plate 31a and the sleeve 133. Collet 134 also has at least one 
indentation or recess 137, which may be engaged by means of a 
corresponding pin 138. 
During operation of the device in accordance with the invention, the core 
30 is inserted into the parison 29, and the entire assembly is lowered 
until it firmly engages with the upper rim of the mold 22, as illustrated 
in FIG. 2 on the right where the components are shown in the closed 
position. The core 30 has seal 30a, which performs the function of sealing 
the core 30 during the subsequent blowing operation. 
When the assembly is positioned in this way, the plate 31b presses the 
quills 135 inward in a radial direction so that the heads 136 lock with 
the neck 29a and prevent deformation thereof during insertion of core 30 
into parison 29. At the same time, the flange of the flanged sleeve 133 
rests on the upper surface of the collet 134. In this position, pressure 
is exerted, not on the parison neck 29a, but only on the upper surface of 
the mold 22, thus preventing damage to, or distortion of, the neck. When 
the components are in this position, the pin 138 engages with the 
identation 137 on the collet 134. Sufficient force, enough to hold the pin 
in position, but not enough to cause it to be displaced, is exerted on the 
pin by a quill, spring or something similar (not shown). In order to 
disengage the core 30 from the parison 29, the assembly described above is 
raised to the open position, as illustrated in FIG. 2 on the left, whereby 
the plate 31b is detached from the mold 22, i.e. leaves the surface of 
contact. This is done by applying sufficient force to disengage the pin 
138 from the identation 137, causing the collet 134 to be displaced 
downwards in the space between plates 31a and 31b and the sleeve 133. When 
the collet is thus displaced, pressure is no longer exerted on the quills 
135, which then spring open and release the neck 29a of the parison. 
While the operation has been illustrated here in connection with the 
tempering mold, it should be noted that the same procedure may be employed 
when transferring the parison to, and removing it from, the finishing mold 
23, by means of an ejector plug 41. 
It should also be noted that the collet 134 and especially the quills 135 
thereof must be made of a flexible material that can be bent repeatedly 
without breaking. Suitable materials include, for example, spring steel, 
alloys of beryllium and/or copper, and synthetics, particularly polyamide. 
This invention may be embodied in other forms or carried out in other ways 
without departing from the spirit or essential characteristics thereof. 
The present embodiment is therefore to be considered as in all respects 
illustrative and not restrictive, the scope of the invention being 
indicated by the appended claims, and all changes which come within the 
meaning and range of equivalency are intended to be embraced therein.