Core rod for the injection blow-moulding of a bottle with an inclined neck

The core rod according to the invention includes a first part (A) for mounting on an injection blow-moulding machine and a second part (B) intended to be received in a mould having an inclined cylindrical stage (30), an inclined part (34) and a connecting zone (36), in order, by the injection blow-moulding technique, to produce a bottle in one piece which has a neck inclined relative to the axis of the bottle.

The invention relates to a core rod for producing a bottle with an inclined 
neck by the injection blow-moulding technique. 
One-piece plastic bottles having a neck inclined, for example, at 
20.degree. relative to the axis of the bottle are conventionally produced 
by the extrusion blow-moulding technique. 
This technique does not guarantee a very good surface state inside the 
neck, and this can lead to difficulties, for example in fitting a 
spreading adaptor inside the neck or a pouring spout. Moreover, the 
dimensional variations in the upper part of the bottle which are inherent 
in this technique limit the rate of assembly of such an adaptor. Finally, 
if the adaptor is to be protected by a cap, the latter, which must be 
positioned on the base of the neck, does not always absorb the dimensional 
differences attributable to the extrusion blow-moulding technique. 
A technique for the working of plastics, such as injection blow-moulding, 
uses cylindrical core rods which make it impossible to produce bottles of 
which the neck is inclined at more than a few degrees relative to the axis 
of the bottle. 
The machines used for injection blow-moulding are equipped with three 
stations. 
At the first station, called an injection station, a core rod having the 
form of a hollow cylinder is surrounded by a mould, the walls of which are 
parallel and only a short distance from those of the core rod. Plastic is 
injected under pressure there into the space present between the core rod 
and the mould. When this operation has been carried out, the mould is 
opened and the core rod and plastic coating it are transferred to the 
blow-moulding station. 
At the blow-moulding station, the core rod and its coating are inserted 
into a mould, the walls of which have the shape of the desired bottle and 
are set apart from the material coating the core rod. By blowing air under 
pressure by means of the conduit provided inside the core rod and of a 
valve feeding some orifices, the plastic is laid forcibly onto the walls 
of the mould. The bottle is formed in this way. The mould is subsequently 
opened, and the core rod surrounded by the bottle is transferred to the 
ejection station. 
At the ejection station, the bottle is separated from the core rod which is 
thus ready for another operation. For this purpose, the neck of the bottle 
is slid along the cylindrical core rod. Consequently, the neck can be 
inclined at only a few degrees relative to the axis of the core rod which 
corresponds to the vertical when the bottom of the bottle is placed on a 
horizontal plane. 
To overcome the disadvantages of the extrusion blow-moulding process, the 
object of the present invention is to provide a core rod making it 
possible by injection blow-moulding to produce a bottle having a neck 
inclined at approximately 20.degree. relative to the vertical. 
SUMMARY OF THE INVENTION 
To achieve this, the subject of the invention is a core rod for producing a 
plastic bottle by injection blow-moulding, this bottle have a neck 
inclined relative to the axis of the body of the bottle, the core rod 
comprising a first part for mounting on an injection blow-moulding 
machine, extended by a second part intended to be positioned inside a 
cavity of a mould and comprising a first section which, when in position, 
is in contact with a first wall part of the mould cavity, and a second 
section extending the first section and intended, when in position, to be 
surrounded with play by a second wall part, there passing through the 
first and second parts of the core rod a straight axial blowing conduit, 
of which a connecting end opens out onto an end face of the first mounting 
part and a blowing end opens out at the free end of the core rod, 
characterized in that the said first section comprises a cylindrical stage 
inclined relative to the axis of the conduit, and in that the said second 
section comprises an inclined cylindrical part coaxial relative to the 
said inclined cylindrical stage, an axial cylindrical end part coaxial 
with the conduit and a connecting zone connecting the said inclined 
cylindrical part to the said axial cylindrical part. 
The process for producing a plastic bottle having an inclined neck 
comprises the steps of 
(a) forming a parison around a core rod having a first cylindrical body 
section and a portion inclined relative to the longitudinal axis of the 
cylindrical body section and a straight axial blowing conduit which 
traverses the length of the core rod including said cylindrical body 
section and inclined portion, 
(b) positioning the parison and core rod within a blowing mold comprising 
two parts which form a wall having the desired form for the outer face of 
the bottle and which parts are separated by an inclined plane having the 
same angle of inclination as that of said inclined portion; 
(c) blowing compressed air through said blowing conduit whereby air 
infiltrates between the core rod and parison except in the area of the 
inclined portion of the core rod, thereby forcing the parison onto the 
walls of the mold to form a bottle having an inclined neck; 
(d) allowing the bottle to cool and harden; and 
(e) removing the core-rod by exerting a pull on the bottle in a direction 
parallel to the axis of the inclined cylindrical part of the core rod to 
release the neck of the bottle and exerting a second pull on the bottle in 
a direction parallel to the longitudinal axis of the core rod and sliding 
the bottle along the longitudinal axis of the core rod. 
According to other characteristics: 
the inclined cylindrical stage forms with the axis of the conduit an angle 
substantially equal to the angle of the neck of the bottle in relation to 
the axis of the bottle; 
the inclined cylindrical stage has an outside diameter substantially equal 
to the outside diameter of the neck of the bottle, and the said inclined 
cylindrical part has an outside diameter corresponding substantially to 
the inside diameter of the neck; 
the said angle of inclination is between 3.degree. and 30.degree. . 
Another subject of the invention is a process for the injection 
blow-moulding of a bottle having a neck inclined relative to the axis of 
the body of the bottle, which involves using a core rod according to the 
invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 illustrates a core rod 2 according to the invention in axial 
section. This core rod 2 has a general stepped cylindrical form extending 
between an end mounting face 4 and a free end face 6 of the core rod. 
An axial conduit 8 passes through the core rod 2, and its two ends open out 
respectively onto the faces 4 and 6. 
A first core-rod part A extends from the end mounting face 4 and, starting 
from this face 4, comprises a first cylindrical part 10, a collar 12 and a 
second cylindrical part 14. 
This first core-rod part A is intended to provide for the core rod to be 
mounted on an injection blow-moulding machine (not shown). 
The collar 12 shown in section in FIG. 2 has two bores for receiving screws 
for fastening the core rod to the machine, and two flaps 16 for ensuring 
the angular positioning of the core rod 2 in relation to the machine. 
A second core-rod part B extends the first core-rod part A axially and goes 
as far as the free endface 6. 
This second core-rod part B comprises a first section B1 extending the 
first core-rod part A and itself extended by a second section B2 going as 
far as the free end. 
The first section B1 comprises a first coaxial cylindrical portion 18 of 
the same diameter as the second cylindrical part 14 of the first core-rod 
part A, a second coaxial portion 20 of a diameter larger than that of the 
first portion, and a third coaxial portion 22 of the same diameter as the 
first portion 18. This provides two shoulders 24 and 26 intended for 
interacting with abutments provided in the moulds for positioning the core 
rod 2 axially. 
The third portion 22 has a plane end wall 28 inclined, in this example, at 
20.degree. relative to a plane perpendicular to the general axis. This 
angle corresponds to the desired angle of the neck of the bottle in 
relation to the axis of the latter. 
From this end wall 28, the first section B1 terminates in an inclined 
cylindrical stage 30 extending perpendicularly relative to the end wall 28 
and off-centre relative to this wall. The cylindrical stage 30 has a 
diameter equal to the outside diameter of the neck of the bottle. 
It should be noted that the diameter of the third portion 22 is larger than 
that of the stage 30 by such an amount that the trace of the outer wall of 
the stage 30 on the end wall 28 is contained completely within the trace 
of the outer wall of the third portion 22 on this same wall 28. 
As a result of the inclination of the wall 28, the stage 30 is inclined at 
an angle of 20.degree. relative to the axis of the core rod. 
The first portion B1 terminates in an annular shoulder 32 parallel to the 
end wall 28 of the third stage. 
The second section B2 extends from this shoulder 32 and comprises an 
inclined cylindrical part 34 which extends the inclined stage 30 and the 
outside diameter of which corresponds substantially to the inside diameter 
of the neck of the bottle and which is coaxial with the stage 30. 
This inclined cylindrical part 34 is extended by a connecting zone 36 with 
an axial cylindrical part 38 going as far as the face 6 of the free end of 
the core rod. 
The connecting zone has a variable wall thickness, of which the minimum is 
shown at 36A in FIG. 1. This minimum must be sufficient to withstand the 
pressure of the air which will be blown into the axial conduit 8. 
The axial conduit 8 is intended for receiving a blow-control device to 
allow compressed air to be blown through the face 6. It comprises a first 
cylindrical portion 40 adjacent to the connecting end, this being extended 
in the direction of the face 6 by a second cylindrical portion 42 of 
smaller diameter, thus forming a shoulder 44. 
This second portion 42 is extended by a bore 46 of a diameter smaller than 
that of the second portion 42, a chamfer 48 making the junction between 
the bore 46 and the second portion 42. 
In the vicinity of the face 6, the bore 46 is extended by a third portion 
50 of a diameter larger than that of the bore 46 and opening out onto the 
face 6. 
The blow-control device accommodated in the conduit 8 comprises a head 52 
seated in the first portion 40 of the conduit 8, the said head being 
equipped with a collar intended for coming up against the shoulder 44. 
This head 52 is extended by a cylindrical stem 54 extending in the second 
portion 42 of the conduit 8, the bore 46 and part of the third portion 50. 
Between the chamfer 48 and the head 52, a helical compression spring 56 
surrounds the stem 54 and stresses the head 52 towards the outside of the 
conduit 8. 
The end of the stem 54 located in the third portion 50 of the conduit 8 is 
equipped with a valve 58 designed to be capable of sliding in the third 
portion 50 of the conduit 8 and provided with a collar 60 bearing on the 
face 6 which thus forms the seat of the valve. 
Passages (not shown) put in communication the conduit 8 and an annular 
groove 62 located adjacent to the collar 60 in the valve 58. 
When the core rod is brought to the injection station, as shown in FIG. 3, 
it is surrounded by an injection mould 64 in two halves separated along an 
axial plane (the drawing plane in FIG. 3). Only two parts 66 and 68 of the 
mould are shown. The parts 66 and 68 are laid against one another to form 
a seal against compressed air along an inclined plane 70 perpendicular 
relative to the axis of the cylindrical stage 30 and of the inclined 
cylindrical part 34. This plane passes approximately through the middle of 
this inclined cylindrical part 34. 
When the four parts of the mould are assembled together, they define a 
cavity intended for receiving the core rod 2. 
A wall part of this cavity is in contact sealing against compressed air, 
with clamping, with the first section B1 of the second core-rod part B. 
In contrast, the wall of the cavity is at a slight distance from the walls 
of the second portion B2, the play corresponding substantially to the 
desired thickness of the bottle. 
The sealed space 72 thus delimited surrounds the second section B2 and is 
intended for receiving under pressure the plastic which will subsequently 
form the bottle. 
Moreover, in the lower part 62 of the mould there is an injection hole 74 
opening into the space 72 in the vicinity of the face 6. 
When the injection mould has been installed round the core rod, plastic is 
injected under pressure through the hole 74 and thus fills the space 72. 
The mould is subsequently opened, and the core rod coated with plastic is 
conveyed to a blowing station where it is surrounded by a blowing mould, 
as shown in FIG. 4. 
This blowing mould 80 is of a design similar to that of the injection mould 
64. However, its cavity 82 possesses a wall 84 having the form desired for 
the outer face of the bottle. 
The lower part 86, as seen in FIG. 4, is larger than the lower part of the 
mould 64. This lower part 86 possesses cooling means (not shown). 
It will also be seen, in this example, that the inclined plane of 
separation of the lower part 88 and upper part 90 of the mould is located 
at the junction between the body of the bottle and its neck. 
In this position, air is blown in by means of the control device 
illustrated in FIG. 1 and accommodated in the conduit 8 of the core rod 2. 
For this purpose, a machine device (not shown) pushes mechanically 
downwards on the head 48 counter to the spring 56. 
The collar 60 of the valve 58 moves away from the end blowing wall 6 of the 
core rod 2, thereby opening a passage for the compressed air coming from 
the machine and passing through the axial conduit 8. 
The compressed air infiltrates between the core rod and its coating of 
plastic and lays this onto the wall 84 of the mould 80. 
After the cooling and hardening of the plastic, the mould is removed and 
the core rod equipped with the bottle is conveyed to an ejection station. 
At this station, a pull is exerted on this bottle so as to release the neck 
from the core rod by sliding. 
This is possible, in a first step, by exerting this pull in a direction 
parallel to the axis of the inclined cylindrical part 34. 
In a second step, the elasticity of the wall of the neck of the bottle 
allows it, as a result of a pull parallel to the axis of the core rod, to 
slide along the connecting zone 36 and then the axial cylindrical part 38. 
A core rod making it possible to produce a bottle having a neck highly 
inclined relative to the vertical by means of an injection blow-moulding 
machine has thus been provided. The bottle produced possesses a good 
surface state inside the neck and exact dimensions in its upper part.