Plastic and nonmetallic article shaping or treating: processes – Direct application of fluid pressure differential to... – Including application of internal fluid pressure to hollow...
Reexamination Certificate
2000-04-25
2004-02-17
Davis, Robert (Department: 1722)
Plastic and nonmetallic article shaping or treating: processes
Direct application of fluid pressure differential to...
Including application of internal fluid pressure to hollow...
C264S540000, C425S532000, C425S538000, C425S541000
Reexamination Certificate
active
06692686
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a blow molding method and a blow molding apparatus which are capable of achieving blow molding efficiently with a relatively few molds, cooling blow molding products efficiently in a short period of time, performing a series of blow molding processes including takeout of products and attaching of labels to the molds efficiently, and coping with a variety of production styles ranging from a small scale production to a large scale production.
Blow molding is a popular method for forming hollow containers. In blow molding, a parison extruded from a die head is received by an opened pair of mold pieces of a split mold, the split mold is closed and air is blown into the parison and then the split mold is opened to take out a product.
Blow molding apparatuses for performing such blow molding are generally classified by a manner of moving of split molds into a rotary type blow molding apparatus in which split molds are moved in a circle and a shuttle type blow molding apparatus in which split molds are reciprocated linearly.
In the rotary type blow molding apparatus, split molds mounted on an annular rail are moved in a circle and are opened and closed continuously, whereby blow molding and delivery of a product are completed in one cycle of movement of each split mold on the annular rail.
In the shuttle type blow molding apparatus, two pairs of split molds which reciprocate linearly are provided and these split molds are alternately reciprocated for receiving parisons and for blow molding the parisons.
Accordingly, in a case where a single type of hollow container should be produced in a large scale, the rotary type blow molding apparatus may preferably be employed so that blow molding will be performed efficiently by using a relatively large number, for example 12 to 14, of split molds arranged in a circle.
The shuttle type blow molding apparatus which performs blow molding by alternate reciprocating movement of the two split molds is limited in its blow molding capacity even if the speed of reciprocating movement is increased and, for this reason, is not suitable for a large scale production but suitable for a small scale production.
In a case where a small scale production of various types of products is required for coping with requirement for various types of hollow containers, the rotary type blow molding apparatus has the disadvantage that split molds which are mounted on the apparatus in a set of 12 to 14 split molds must be changed and this takes much time and further it is costly to produce so many split molds.
The shuttle type blow molding apparatus is suitable for such small scale production of various types of products in that change of split molds does not take much time because the number of split molds used is small and the manufacturing cost of split molds is relatively small. The shuttle type blow molding apparatus, however, is limited in its blow molding capacity in a case where a large scale production is required.
There are many cases where a label must be attached to a product which has been produced by blow molding and, in such cases, a label is generally attached to a product simultaneously with performing of blow molding. For this purpose, a product is taken out of an opened split mold after blow molding by means of a product takeout robot and thereafter a label is attached to the split mold by means of a label attaching robot. Thus, two different robots are required and, since it takes a long cycle time for operating these robots, an efficient blow molding cannot be achieved.
Further, the cycle time of the operation of the robots is determined by speed of cooling in blow molding. Cooling of the inside of a parison is difficult when a label is attached so that improvement in efficiency in cooling is desired for.
Furthermore, a product taken out of a split mold generally has flash and, therefore, a step using a device for removing flash from the product becomes necessary for obtaining a final product by blow molding.
It is, therefore, an object of the invention to provide a blow molding method and a blow molding apparatus which are capable of performing blow molding efficiently with a relatively few split molds.
It is another object of the invention to provide a blow molding method and a blow molding apparatus which are capable of cooling a product efficiently in a short period of time.
It is another object of the invention to provide a blow molding method and a blow molding apparatus which are capable of efficiently performing a series of blow molding operations including taking out of a product and attaching of a label to a split mold.
It is still another object of the invention to provide a blow molding method and a blow molding apparatus which are capable of performing blow molding efficiently both in a small scale production and in a large scale production.
SUMMARY OF THE INVENTION
For achieving the above described objects of the invention, there is provided a blow molding method comprising steps of moving a split mold to a parison receiving position where a parison is supplied and receiving the parison, closing the split mold, performing blow molding at a blow molding position, and opening the split mold at a product discharging position and thereby discharging a product, said method further comprising steps of:
sequentially reciprocating each split mold in trains of split molds provided opposed to each other across the parison receiving position to and from a position opposed to the parison receiving position; and
sequentially reciprocating the split mold between the position where the split mold is opposed to the parison receiving position and the parison receiving position for performing blow molding.
According to the invention, by combination of the two reciprocating movements, namely the reciprocating movement of the trains of split molds to and from the position opposed to the parison receiving position and the reciprocating movement of the split molds between the position opposed to the parison receiving position and the parison receiving position, blow molding can be performed efficiently with a smaller number of split molds and replacement of split molds can be finished in a shorter period of time than the blow molding using the rotary type blow molding apparatus.
In one aspect of the invention, the direction of reciprocation of each split mold in the trains of the split molds to and from the position opposed to the parison receiving position crosses, at right angle, the direction of reciprocation of the split mold between the position opposed to the parison receiving position and the parison receiving position.
According to this aspect of the invention, blow molding can be performed simply and efficiently by the two reciprocating movements crossing at right angle such as x-y directions.
In one aspect of the invention, a plurality of parisons are supplied simultaneously at the parison receiving position to each split mold which are adapted to receive the plurality of parisons.
According to this aspect of the invention, the blow molding capacity is improved by the multiple supply of parisons and the multiple cavities of the split mold.
In another aspect of the invention, there is provided a blow molding method comprising steps of performing blow molding by supplying a parsion in a split mold and closing the split mold and thereafter discharging a product by opening the split mold at a product discharging position, said method further comprising steps of:
reciprocating a pair of arms capable of being opened and closed relative to each other between the product discharging position, a first delivery position and a second delivery position provided at an equal interval downstream of the product discharging position in the direction of delivering the product, said pair of arms having length corresponding to the interval between the first delivery position and the second delivery position and a label supplying section being provided in correspondence to the first delivery position; and
opening an
Gonda Toshiaki
Miura Hideo
Miyazaki Takashi
Noma Hiroshi
Davis Robert
Hedman & Costigan ,P.C.
Toyo Seikan Kaisha Ltd.
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