Plastic and nonmetallic article shaping or treating: processes – Direct application of fluid pressure differential to... – Perforation by differential fluid pressure; or smoothing,...
Reexamination Certificate
1996-01-11
2001-04-17
Vargot, Mathieu D. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Direct application of fluid pressure differential to...
Perforation by differential fluid pressure; or smoothing,...
C264S520000, C264S526000, C264S540000
Reexamination Certificate
active
06217817
ABSTRACT:
TECHNICAL FIELD
This invention relates to a method for blow-molding a tube container and, more particularly, to a blow-molding method which enables one to shorten the time for cooling moldings immediately after being blow-molded and to effectively produce moldings having good dimensional accuracy.
PRIOR ART
In molding a tube container from a thermoplastic resin according to blow molding technique, it has been known to pierce the upper portion of a parison having been melt extruded from an extruder with a blow nozzle for introducing blow air, and blow compressed air into the parison through the nozzle, or to introduce compressed air into the parison from the upper portion or lower portion in the axial direction to thereby press the parison against the wall of a mold for shaping a closed-end cylindrical container, followed by cooling the container, taking it out of the mold, and cutting the lower portion thereof to produce a tube container.
The thus molded tube container is engaged with a cap, and the capped tube container is fed to a filling machine. Then, the tube container is filled with contents through the cut portion, and the cut end is sealed. The resulting tube containers are then brought to the market.
Japanese Examined Patent Publication No. S59-3260 discloses a blow molding method for producing hollow containers, in which nip-pressing plates located at the upper position of a split mold for holding a softened parison are not directly in contact with each other but are formed partly with a space therebetween, the nip-pressing plates co-work to nip the parison, the thus-sealed parison is pierced at its side wall with a blow nozzle, blow air is continuously fed through the blow nozzle to shape a hollow container, then the space portion of said nip-pressing plates are broken by the pressure of blow air to form a discharge outlet through which the pressing fluid filling the mold is discharged.
PROBLEMS THAT THE INVENTION IS TO SOLVE
As another conventional process for blow molding a hollow container such as a tube container, blow air introduced through a blowing inlet presses the softening-state parison against the wall of the mold to shape a tube container, then is discharged through a discharge outlet formed above the blow nozzle-pierced portion. However, since the molded tube container has a long and narrow form with a closed end, the blow air is discharged before sufficiently flowing within the tube container. Therefore, the blow air used for shaping the tube container does not flow but remains in the lower portion of the container. Thus, subsequent cooling of the wall of the tube container is mainly conducted by circulating cooling water in the mold in contact with the tube container.
However, this method requires a considerably long time for cooling the shaped tube container still kept at an elevated temperature to such a degree that the mold can be opened. Thus, there arises a problem in view of molding efficiency.
That is, in the conventional blow molding method for producing a tube container, cooling of the shaped moldings have been conducted only by cooling the mold, and nothing has been taken into consideration for enhancing cooling efficiency. In addition, although the manner of piercing the wall of a parison with a blow nozzle and shape of an air-introducing inlet have been studied, no attention has been paid to how the blow air introduced through the nozzle can most effectively shape and cool the molding (tube container).
OBJECTS OF THE INVENTION
An object of the present invention is to provide a method for blow molding a tube container, in which blow air introduced into the tube container will circulate therein even after shaping of the tube container to rapidly cool the tube container.
SUMMARY OF THE INVENTION
The present invention is proposed for attaining the abovedescribed objects and relates to a method for blow molding a tube container, which comprises forming a discharge outlet for discharging blow air simultaneously with, or immediately after, shaping of the tube container in an unnecessary lower portion of the tube container to be cut off after molding, to thereby discharge successively introduced blow air.
That is, according to one aspect of the present invention, there is provided a method for blow molding a tube container using a parison having been extruded from an extruder, which comprises introducing blow air into the parison to shape a tube container, forming an outlet in the wall of an unnecessary portion of the tube container located on the opposite side where a blow air-introducing inlet is provided, and continuing feeding of the blow air.
According to another aspect of the present invention, there is provided a blow molding method for blow molding a tube container using a parison having been extruded from an extruder, which comprises introducing blow air into the parison to shape a tube container, forming an outlet in the outer wall of a portion of the tube container to be cut off, and continuing feeding of the blow air.
As to the manner of introducing blow air, either horizontally blowing type in which the wall of a parison having been extruded from an extruder is pierced with a blow nozzle for introducing blow air or vertically blowing type in which blow air is introduced in the axial direction of the parison, i.e., in the downward or upward direction, can be used.
The discharge outlet is preferably formed in the tube container simultaneously with or after shaping of the tube container. However, it may be formed during shaping or, for the reason of mechanical timing, some time after shaping.
Alternatively, the discharge outlet may be formed by pressing the wall of a softened tube container against an opening of the passageway formed in the wall of the mold and connecting to the cavity using the blow air, or by piercing the container with a needle-like member from outside the mold.
In the case of conducting the blow molding of the present invention in a horizontally blowing manner, another similar discharge outlet may be formed in the vicinity of or above the blow nozzle-pierced portion after forming a discharge outlet in part of the lower wall of the portion of tube container to be cut off.
The thus formed discharge outlet serves to effectively cool the portion in the vicinity of the blow nozzle-pierced portion.
REFERENCES:
patent: 3114931 (1963-12-01), Pelikan
patent: 3197532 (1965-07-01), Maass
patent: 3337911 (1967-08-01), Settembrini
patent: 3338998 (1967-08-01), Di Settembrini
patent: 3450805 (1969-06-01), Chesser
patent: 3492106 (1970-01-01), Peters et al.
patent: 3505442 (1970-04-01), Culpepper
patent: 3592886 (1971-07-01), Havely
patent: 3661483 (1972-05-01), Bose
patent: 4092389 (1978-05-01), Sakurai
patent: 1220563 (1960-03-01), None
patent: 74.14738 (1974-11-01), None
patent: 38-11831 (1938-07-01), None
Takakusaki Nobuyuki
Takeda Isamu
Terajima Yoshimi
Armstrong Westerman Hattori McLeland & Naughton LLP
McDowell Suzanne E.
Toyo Seikan Kaisya, Ltd.
Vargot Mathieu D.
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