Head tooling parison adapter plates

Plastic blow molding equipment of a type including a die housing with a tubular chamber disposed therein. The die housing includes an inner portion on the inside of the tubular chamber and an outer portion on the outside of the tubular chamber. The tubular chamber has an outlet therein. Head tooling is attached to the die housing and this head tooling has a tubular passageway therethrough of an unequal diameter throughout the length thereof. The tubular passageway in the head tooling is in communication with the outlet in the die housing. An adjusting mechanism is associated with the head tooling for forming a parison outlet of different sizes. The adjusting mechanism includes an inner section inside of the tubular passageway and an outer section on the outside of the tubular passageway. The inner section includes a plurality of inner plates each having a progressively larger outer diameter from one end of the head tooling to the other end thereof, and the outer section includes a plurality of outer plates having an inner surface with a progressively larger diameter from one end of the head tooling to the other end thereof.

TECHNICAL FIELD 
The present invention relates generally to plastic blow molding equipment 
and more particularly to an improved apparatus for quickly and easily 
changing the opening diameter of the head tooling so as to be able to 
adjust the diameter of a parison formed thereby. 
BACKGROUND ART 
In plastic blow molding equipment, the head tooling determines the diameter 
of the parison formed by such equipment. It is often necessary to change 
the head tooling to form parisons of a different diameter when it is 
desired to blow mold a product larger or smaller than the last object 
molded by such equipment. If the parison formed is too small, the walls of 
the object being blow molded are likely to be too thin, at least in 
places. 
If the parison is too large for the product being formed, plastic material 
is wasted and a build-up of excess material due to such excessively large 
parisons can cause a malfunctioning of the equipment. Consequently, the 
head tooling must be changed from time to time to obtain the optimum sized 
parison for the particular product to be formed. 
This changing of the head tooling is a time-consuming job, which is 
expensive, not only from a labor standpoint, but most importantly because 
the expensive equipment is shut down during such process. Such loss of 
productivity results in a loss of thousands of dollars of product. 
Consequently, there is a need for an apparatus which can reduce the time 
for changing head tooling to convert the parison being formed from one 
diameter to another. 
DISCLOSURE OF THE INVENTION 
The present invention relates to plastic blow molding equipment of a type 
including a die housing with a tubular chamber disposed therein. The die 
housing includes an inner portion on the inside of the tubular chamber and 
an outer portion on the outside of the tubular chamber. The tubular 
chamber has an outlet therein. Head tooling is attached to the die housing 
and this head tooling has a tubular passageway therethrough of an unequal 
diameter throughout the length thereof. The tubular passageway in the head 
tooling is in communication with the outlet in the die housing. An 
adjusting mechanism is associated with the head tooling for forming a 
parison outlet of different sizes. The adjusting mechanism includes an 
inner section inside of the tubular passageway and an outer section on the 
outside of the tubular passageway. The inner section includes a plurality 
of inner plates each having a progressively larger outer diameter from one 
end of the head tooling to the other end thereof, and the outer section 
includes a plurality of outer plates each having an inner surface with a 
progressively larger diameter from one end of the head tooling to the 
other end thereof. 
An extruding mechanism is provided for delivering a deformable material in 
a plastic condition to the tubular chamber and forcing such deformable 
material through the tubular chamber in the die housing and through the 
tubular passageway in the head tooling to form a parison attached to the 
outlet of the head tooling. 
An object of the present invention is to provide an improved head tooling 
apparatus. 
Another object is to provide an apparatus for easily and quickly adjusting 
the size of the outlet opening on head tooling. 
Other objects, advantages, and novel features of the present invention will 
become apparent from the following detailed description of the invention 
when considered in conjunction with the accompanying drawings.

BEST MODES FOR CARRYING OUT THE INVENTION 
Referring now to the drawings wherein like reference numerals designate 
identical or corresponding parts throughout the several views, FIG. 1 
shows blow molding equipment (10). The blow molding equipment (10) 
includes an extruder (11) for heating up plastic material to be used in 
forming containers or the like and delivering it to a die head (12) having 
a screw parison adjustment (13) thereon. 
Mold halves (14) and (15) are attached to platens (16) and (17) which are 
connected slideably together by support rods (18) and (19). Guide pins 
(21) on mold half (14) extend into depressions (22) in mold half (15) for 
insuring that when the mold halves (14) and (15) come together they will 
be in a proper relative relationship. 
Water lines (23) and (24) extend into the mold halves (14) and (15) for 
cooling down the mold and making the product hard so that it will hold its 
shape after it is ejected from the mold. An air line (25) is attached to 
the equipment for blowing air down to and through an air pin (26) which 
extends inside of a parison (27). 
Referring to FIG. 4, the present invention relates to the head tooling (30) 
which includes a plurality of inner plates (31), (32) and (33) and a 
plurality of outer plates (35), (36) and (37). Bolts (34) are threadably 
engaged into openings (38) in the die head (12) and into openings (39) in 
an inner portion (28) of the die head (12). A plastic material can extend 
through the tubular chamber (40) between the outer die head (12) and the 
inner die head part (28) and leads to a tubular passageway formed between 
the plates (31), (32) and (33) and the outer plates (35), (36) and (37) to 
form an outlet (41) which causes the parison (27) to be of the diameter 
shown in FIG. 4. 
The head tooling embodiment (30) shown in FIGS. 4, 5 and 6 is generally 
known as a diverging type because the diameter of the cylindrical 
passageway (43) formed between the plates (31), (32) and (33) and the 
outer plates (35), (36) and (37) generally gets larger as the material 
flows along the passageway (43). 
In operation, the blow molding equipment (10) would have plastic in 
granulated form entering the extruder (11) via a hopper (not shown). The 
plastic material becomes a molten resin around a heated screw (not shown). 
This screw will push the resin into an accumulator (not shown) and a ram 
(not shown) will push the resin into the die head (12) through chamber 
(40) and passageway (43) to form a parison (27) of a size shown in FIG. 3. 
Since the parison formed in FIG. 3 is too small for the part being formed, 
the head tooling (30) would be attached thereto in an appropriate size 
with an appropriate number of plates in order to form the diameter of the 
parison (27) desired. This parison (27) will hang between the two mold 
halves (14) and (15), as shown in FIG. 1, which are clamped onto platens 
(16) and (17). When the platens (16) and (17) close together, the parison 
(27) will be pinched off on the top and bottom, for example, as shown in 
FIG. 2. The mold halves (14) and (15) have a relief area to allow for 
excess material. The rest of the parison (27) is encapsulated in the mold 
cavity (29), although sometimes this is not possible due to configuration 
of the part and the parison is pinched off all around the edge of the 
cavity (29). 
In the case of a conventional top blow set-up, air is blown into the mold 
through the center of the die head (12) and through the head tooling (30) 
via a blow pin (26). Referring to FIG. 2, the parison (27) is then blown 
onto the cavity walls just like a balloon. The mold is then internally 
cooled so that the material sets up to form a final part. The diameter of 
the parison (27) is in direct relation to the size and shape of the mold 
cavity (29). The parison (27) as shown in FIG. 3 has to stretch a long way 
into the corners, which means that the part will get very thin at this 
location if the parison of this size is used. Consequently, using the 
prior art technology, the entire head tooling assembly would have to be 
changed to form a larger parison, which is a heavy and tedious job. By 
bolting on an appropriate number of plates, such as shown in FIG. 4, the 
size of the parison can easily be changed. If, for example, a smaller 
parison (27) is desired than that shown in FIG. 4, then the bolts (34) 
could be removed and plates (33) and (37) could be removed with the bolts 
(34), or a shortened form thereof, being reattached so that the plates 
(31), (32), (35) and (36) would still be held in place and the smaller 
parison (27) would be formed. If a still further reduction in the diameter 
of the parison (27) is desired, more pairs of inner and outer plates (31) 
or (32) and (35) and (36) could be removed. It will also be understood to 
those skilled in this art that more plates could be added beyond the three 
pairs shown in FIG. 4, in order to increase the size of the parison from 
that shown in FIG. 4. 
Referring now to FIG. 7, it is noted that an alternate embodiment (50) of 
the head tooling adjusting mechanism is shown. The head tooling adjusting 
mechanism is of a converging type wherein the passageway (43) gets smaller 
as it gets closer to the outlet opening (41), which is just opposite from 
the diverging head tooling apparatus (30) shown in FIG. 4. It will be 
readily appreciated by those skilled in this art that to make the parison 
(27) smaller than that shown in FIG. 7, one or more of sets of inner and 
outer plates can be removed. For example, if a slightly larger parison 
(27) is desired, plates (53) and (57) could be removed and the other 
plates bolted back in place. If a still larger parison diameter is 
desired, the inner and outer plates (52) and (56) could be removed, 
bolting the plates (51) and (55) back in place. If a still further 
increase in the parison size (27) is desired, then all of the plates, 
including plates (51) and (55), would be removed. 
It will be understood to those skilled in this art that if it is desired to 
form a parison of a diameter larger than the outlet (49) shown in FIG. 3, 
the diverging head tooling apparatus (30) would be utilized; and, if it is 
desired to provide a parison having a diameter smaller than the diameter 
of the outlet (49) shown in FIG. 3, the converging head tooling apparatus 
(50) of FIG. 7 would be utilized. 
Accordingly, it is believed to be clear that all of the aforementioned 
objects have been accomplished. Obviously, many modifications and 
variations of the present invention are possible in light of the above 
teachings. It is therefore to be understood that, within the scope of the 
appended claims, the invention may be practiced otherwise than as 
specifically described.