Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – To produce composite – plural part or multilayered article
Reexamination Certificate
1999-06-02
2002-04-16
Ortiz, Angela (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
To produce composite, plural part or multilayered article
C264S261000, C264S297200, C264S297800, C425S123000, C425S129100, C425S572000, C425S574000
Reexamination Certificate
active
06372170
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and an apparatus for manufacturing a synthetic resin hollow member by bringing a pair of synthetic resin molding half bodies into abutment each other and joining the resin-made half bodies together at their abutting portions, also relates to a method and an apparatus for manufacturing a synthetic resin hollow member with a filter (filtering material) or other intermediate element incorporated therein.
2. Description of Related Art
Conventionally, as a method for manufacturing a synthetic resin hollow member, as disclosed in, for example, Japanese Patent Application Laid-Open Publication (Kokai) No.7-217755, there is a known method utilizing the so-called “die slide injection (DSI) method” wherein a die assembly including a pair of dies is used such that one of the dies has a male molding portion and a female molding portion for molding one separate half body and the other die has a female molding portion and a male molding portion provided in opposed relation to the molding portions of the one die, and wherein after separate half bodies are simultaneously molded by using the die assembly (first injection), one of the dies is caused to slide relative to the other die so that separate half bodies left in the respective female molding portions are brought into abutment with each other before die clamping, with a molten resin being injected onto peripheral edges of the abutting portions (second injection) to join the two half bodies together.
According to this DSI method, productivity can be considerably enhanced over the conventional method in which molding of separate half bodies and abutting/joining of the half bodies are performed in completely separate processes. Also, the DSI method more reliably assures bond strength and a positive seal at the joint when compared with conventional methods of bonding the half bodies with adhesive or by heat fusion.
The DSI method can also be used to efficiently manufacture a synthetic resin hollow member with a filter (filtering material) or other intermediate element inside the finished product. In this case, after the synthetic resin hollow member is molded by the first injection as described in the above prior art, die opening is carried out once for insertion of a separately made intermediate element into one of the half bodies, after which the sliding and clamping of the dies are performed, the second injection is carried out.
In the DSI method, generally, a pair of male molding portion and female molding portion is provided in relative sliding direction on each die, and a single hollow member is obtained with every two die sliding operations. However, as a method for further improvement of the productivity in the DSI method, for example, in Japanese Patent Application Laid-Open Publication (Kokai) No.4-331117 or No.4-331123, there is disclosed the so-called “double DSI method” wherein a set of male molding portion and female molding portions is provided in parallel (that is, plural rows are placed perpendicular to the die sliding direction) in each die.
According to this plural rows type (double) DSI method, one hollow member is obtained with each die sliding operation, and thus further improvement of productivity is achieved.
A problem with this conventional double DSI method is that the width of the die (that is, the dimension perpendicular to the die sliding direction) is unavoidably increased by disposing plural rows of molding portion pairs in each die, and more space is therefore required in this direction. Furthermore, this problem is even greater when the product being manufactured is long in this lateral direction.
Molding machine size is also related to the die width, and an increase in die width tends to increase production equipment cost and the cost of production. It is therefore necessary and desirable to keep the dies as small as possible so that the smallest possible molding machines can be used for production.
Also, when a synthetic resin hollow member with an intermediate element incorporated therein is manufactured using this DSI process, as described above, the intermediate element manufactured in a separate process is placed in one of the half bodies, after the first injection step and before the second injection step. This obviously means that a manufacturing process completely separate from that in which the hollow member half bodies are molded, mated, and bonded is required to manufacture the intermediate element incorporated into the hollow member. The separately manufactured intermediate elements must also be separately inventoried and managed, thus further complicating cost reduction efforts. Differences between half bodies molded in the first injection step and the intermediate element manufactured by the separate process, in molding conditions, temperature when the intermediate element is inserted into one of the half bodies, and other conditions also make it difficult to improve assembly characteristics and precision of the intermediate element assembled into the half bodies.
Another problem occurs when manufacturing two similar synthetic resin hollow bodies that have the same function and basic size and differ only partly in shape or orientation, such as right and left handed components. Conventional methods require dies that differ only in part, and the components are also manufactured in different production lots.
It will be obvious that die costs could be held down and production control significantly simplified if such nominally different products could be manufactured using the same dies as part of the same production lot.
It is therefore an object of the present invention to provide a method and an apparatus for manufacturing a synthetic resin hollow member whereby: an increase in die width is not incurred; one hollow member can be obtained with each die sliding operation; intermediate elements can be molded as part of the process for molding, mating, and bonding hollow member half bodies; or two different hollow bodies can be obtained using the same dies.
SUMMARY OF THE INVENTION
To achieve the above object, a method according to a first aspect of the present invention for manufacturing a synthetic resin hollow member bringing a pair of synthetic resin-made half bodies into abutment each other and joining these half bodies together at their abutting portions uses a molding apparatus for a die slide injection molding and comprises steps as described below. This molding apparatus more specifically comprises a first die having formed lengthwise thereto a series of molding portions in male-female-female-male sequence with a specific spacing therebetween, and a second die having formed lengthwise thereto a series of molding portions in female-male-female sequence with a specific spacing therebetween. The dies can be mutually opened/closed, and can be slid lengthwise a specific pitch relative to each other.
The steps of this manufacturing method include a die clamping step for closing and clamping the first and second dies. An injection step following the die clamping step forms first and second molding half bodies for a present cycle in a combination of male and female molding portions by injecting molten resin to a cavity formed between the dies, and joins first and second molding half bodies from a preceding cycle in a combination of female molding portions by injecting molten resin to their abutting portions. A removal step following the injection step opens the first and second dies and removes a hollow member formed by bonding half bodies from the previous cycle. A die sliding step following the injection step slides the first and second dies lengthwise a specific distance relative. to each other in a direction opposite that in which the dies were slid in the previous cycle. These steps are then repeated to manufacture one hollow member of bonded first and second half bodies each time the dies are slid relative to each other.
A molding apparatus used in this method for manufacturing a synthetic resin ho
Nishida Michinori
Nishida Shoso
G P Daikyo Corporation
Ortiz Angela
LandOfFree
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