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
2000-10-31
2003-09-02
Mackey, James P. (Department: 1722)
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
C264S297200, C264S328800, C425S112000, C425S190000, C425S576000, C425S594000
Reexamination Certificate
active
06613262
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to molding machines, wherein mold parts and their platens are pressed and retained together during a molding process. Tie rods extend between and secure the mold part platens together during the molding process, and are separated to release the molding product. The present invention is especially applicable to large, high tonnage injection molding machines.
Injection molding devices or apparatuses typically include separable mold parts which are movable between open and closed positions. When the mold parts are closed together, a mold cavity is defined therebetween for receiving injected material, which is introduced therein in a fluid state under high pressure. After the injected material has hardened, the mold parts are opened or separated and the formed product is removed from one of the mold parts.
After a product is molded between the mold parts of a conventional molding machine, there is a down time or delay while the molded product is removed from the molding machine. The molding machine cannot mold a second product until the first molded product has been completely removed from the mold parts and the system is reset or realigned to mold the second product.
Also, because many molding machines remain aligned when the parts are separated, the operator may have to reach between the mold parts to remove the molded product and to prepare the mold parts for the next product. Therefore, it may be dangerous to remove the molded products from the mold parts of conventional molding machines, since an operator must reach or stand between the mold parts to access the molded product. U.S. Pat. No. 4,708,625 discloses a reaction injection molding (RIM) machine which books the platens and mold parts to provide safe access to the mold parts between molding processes.
Because the fluid material is injected into the mold part cavity under high pressure, the mold parts tend to separate during the molding process. As the size of the systems increase, the forces tending to separate the mold parts are correspondingly increased. Typically, the injection molding apparatus includes a platen at each of the mold parts. The tie rods extend between the platens and secure the platens relative to one another such that the mold parts are joined together, in order to resist the forces tending to separate the mold parts and platens during the molding process.
The tie rods extend a predetermined length from one of the mold parts and typically require a mold height adjustment in order to accommodate mold parts of different depths or heights. The tie rods are adjusted to extend an appropriate amount from one of the platens, such that when the two platens are moved to their engaged position, the tie rods extend a sufficient length for engaging and securing to the other platen. Typically, the mold height adjustment is accomplished via a mechanical adjustment of the tie rod. The tie rods are then extended the appropriate amount from the platen in which they are mounted.
Typically, the tie rods are positioned at various locations around the platens and may surround the mold parts. Because the tie rods typically are not movable with respect to one of the platens, the tie rods may interfere with access to the mold parts and the mold part cavity. This concern is even greater with larger injection molding apparatuses where a greater number of tie rods may be required to resist the forces tending to separate the mold parts. The position of the tie rods thus may result in limiting the size of a part which can be molded by a particular molding apparatus, and may further result in the removal of the molded part becoming a difficult and even dangerous process.
One proposed system is disclosed in U.S. Pat. No. 5,417,913, which provides tie rods which are movable relative to the platens, such that the tie rods may be spaced from the gap between the platens when the platens are separated. This allows for easier access to the mold parts when the platens and mold parts are separated.
When multiple colored or multiple layered items or products are molded by an injection molding machine, a single color or portion of the product or item is molded at one time. In such applications, multiple mold parts are typically spaced on one of the platens, whereby a color or portion of the product is shot or molded separately at each of the mold parts. The mold parts are then indexed so the next mold device can mold the second color or portion of the product. Because multiple mold parts for the different portions of the product are spaced on the platens of the molding apparatus, the size of the product must be small enough to utilize only a portion of the platen, in order to provide room for the other mold parts for other portions of the product about the platen. Furthermore, because the size of the mold part that is available for molding a product is determined by the size of the platens and by the position of the tie rods about the mold parts, a larger machine may be needed to mold multi-colored products or a given machine may be limited to molding smaller products. Accordingly, the process for molding multiple colors or layers of products may require removal of the partial product to place the partially molded product in a second mold cavity for subsequent molding of a second or third portion of the product.
Therefore, there is a need in the art for a molding apparatus which provides movable tie rods which are easily adjustable and movable to also provide clearance and access to the mold part platens when the platens are separated. The tie rods should also be adjustable to account for mold height variation for different mold parts. Also, there is a need for a molding apparatus which provides safe and easy access to the mold parts between molding processes. There is a further need in the art for a molding apparatus which is capable of molding multicolored parts in an efficient and effective manner.
SUMMARY OF THE INVENTION
The present invention is intended to provide a molding apparatus which provides movable tie rods which are retractable such that the tie rods are removed from the gap between the mold platens when the mold platens are separated, thereby easing access to the mold parts. The present invention is also intended to provide a molding machine which enhances access to the molded product via booking of a fixed platen for access to the molded product. The present invention may also provide simultaneous molding of a second product while the first product is booked for removal, thereby increasing the efficiency of the system.
According to an aspect of the present invention, a mold assembly for molding products between a pair of mold parts comprises a support base, a fixed platen support positioned at a first end of the support base, and at least one movable mold module which is movably supported along the support base toward and away from the fixed platen support. The fixed platen support includes at least one fixed platen which supports one of the pair of mold parts. The movable mold module includes a movable platen carriage, which supports a movable platen, which further supports the other of the pair of mold parts. The movable platen carriage is movable along the support base toward and away from the fixed platen support. The movable platen is movable between an engaged position, where the mold parts are engaged together for molding, and a separated position, where the mold parts and platens are separated. The movable mold module further includes at least one tie rod assembly movably mounted at the movable platen carriage. The tie rod assembly is movable with respect to the movable and fixed platens. The tie rod assembly is initially removed from proximity of the mold parts when the mold parts and platens are separated and is movable along the movable platen carriage to extend from the movable platen carriage and engage the fixed platen support to maintain engagement of the platens and the mold parts during the molding process.
Preferably, the tie rod assembli
Mackey James P.
Van Dyke Gardner, Linn & Burkhart, LLP
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