Plastic article or earthenware shaping or treating: apparatus – With apparatus assembly or dismantling means or with idle part – For extrusion or injection type shaping means
Reexamination Certificate
1993-11-01
2001-01-09
Mackey, James P. (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
With apparatus assembly or dismantling means or with idle part
For extrusion or injection type shaping means
C425S338000, C425S588000, C425S589000, C425S451300
Reexamination Certificate
active
06171094
ABSTRACT:
BACKGROUND OF THE INVENTION
Injection molds for containers, lids, and the like are typically of a fairly complex construction, comprising mold plates, leader pins, bushings, a hot runner system, an ejection system, a water and/or air cooling system, an opening and closing mechanism, and often a mold outrigger support system. Furthermore, such molds generally must be specifically manufactured to fit the desired molding press. Molding machines or presses come in various sizes and capacities, ranging typically from 200 tons to 700 tons.
Conventional molds may have a runner plate, which is a plate that typically holds a mold cavity on one side thereof, or a pair of mold cavities on opposed sides, and which has conduits that supply molten molding compound to the respective sprues of the mold cavities. Runner plates may be supported by outriggers, extending from corners of a rectangular runner plate in prior art designs in a direction parallel to a rectangular side thereof and integrally attached thereto. These outriggers are proportioned to rest upon tie bars of a particular molding press. In the prior art, the outriggers must be of a particular design to engage the particular tie bars of the desired molding press, since various molding presses of differing capacities and manufacture have tie bars of different spacing and size.
Thus, it is typically impractical to switch a mold from operation in one molding press to another molding press of different design, for example a molding press of larger capacity. In the prior art, the outriggers of the runner plate are likely to fail to engage the differently spaced tie bars of another design or size of molding press.
Furthermore, in the prior art molds where the runner plate carries a pair of mold cavities in back-to-back relation, it is conventional for leader pins to be present for lateral bracing of the mold as it opens and closes. Typically, one set of leader pins extends from one of the mold cores, secured in stationary manner on a mold core plate, which, in turn, is secured to a platen of the mold press. The leader pins from this first mold core plate extend outwardly through a peripheral aperture in the runner plate, being long enough to continue engaging the runner plate in the mold-open position, but not significantly longer than that. Then, the other mold core, on the other side of the runner plate and which engages the corresponding mold cavity on the other side of the runner plate, carries another set of leader pins through its mold core plate which are long enough to extend through apertures in the periphery of the runner plate as the entire structure is moved between open and closed positions, but likewise not significantly longer.
Thus, when such a prior art mold is in its open position, the leader pins are near their maximum position of extension, where only essentially the tips of the leader pins occupy the apertures in the runner plate. They would disengage from the runner plate if the mold were open much further, but the mold is designed not to open further. However, there is a weakness of lateral stability created by this structure, that has in the prior art been dealt with by the use of the outriggers described above for added lateral stability.
In accordance with this invention, a mold is provided having improved lateral stability, with the mold also exhibiting a universal characteristic of use, in that the very same mold may be run in a variety of molding presses. For example, preferred molds may be run in a variety of molding presses which range in capacity from 150 tons to 700 tons. This provides a significant and novel advantage, in that, in the prior art, it has typically been necessary to rebuild a mold with redesigned outriggers in order to switch its use from one press of one capacity or design to another press of a different capacity or design.
Further in accordance with this invention, one embodiment permits the elimination of the outrigger supports altogether, if that is desired.
Thus, a great improvement is provided with the mold of this invention.
DESCRIPTION OF THE INVENTION
In this invention, an injection mold is provided having a runner plate which comprises: a plate having a plurality of corners, apertures extending through the runner plate for receiving leader pins of the molding system for support of the plate. At least a pair of outrigger supports are provided, the outrigger supports being carried by the plate, each at a different edge portion of the plate and extending diagonally outwardly relative to adjacent plate edges. Because of the diagonal extension of the outrigger supports, they are capable of engagement with a variety of tie bars of differently sized mold presses, to facilitate the mounting of a mold having a runner plate in accordance with this invention in mold presses of different size or design.
Preferably, each outrigger support carries a roller which is positioned to engage the tie bars of the mold press in rolling contact therewith for support of the mold. Thus, sliding friction is greatly reduced in the mold operation.
Furthermore, the outrigger supports are adjustably positionable, as well as removable from, the runner plate, typically so that the same outrigger supports may be applied to the runner plate in a different position. For example, this permits the runner plate to be placed on the tie bars of a mold press with the long, transverse dimension of the runner plate being vertical, or, alternatively, with the long, transverse dimension of the runner plate being horizontal. This is typically accomplished by removing and replacing the outrigger supports at respective corners of the runner plate to permit this.
Specifically, each outrigger support carries a sliding projection, for example of T-shape, while at least three corners of the runner plate defines slots proportioned to receive and retain sliding projections of the outrigger supports. Thus, the pair of outrigger supports may be changed in their position on the runner plate between the respective corners, to permit changing of the runner plate position relative to the molding system between vertical and horizontal, for example. Also, the sliding projections may have a range of different positions in the runner plate slots so that the outrigger supports may be adjusted to engage differently-positioned tie bars of different mold presses. Means such as set screws may be used to hold the outrigger supports in their desired positions in the runner plate slots.
The runner plates may be broadly rectangular in shape, but typically carrying a pair of opposed side projections which define apertures carried adjacent the longest edges of the plate. The apertures of the side projections may receive the leader pins, which slide relative to the runner plate as the mold opens and closes. The side projections may typically be 18 to 30 inches in length along the longest edges, but less than the length of the longest edges of the runner plate. Specifically, a runner plate in accordance with this invention may have a length of 28 to 40 inches and a width of 14 to 28 inches, which dimensions accommodate a substantial variety of mold presses. A mold made in accordance with this invention may be interchangeably used in many of such presses.
Also, the molding system of this invention may comprise a pair of mold cavities carried on opposite sides of the runner plate, plus a pair of mold cores, each being positioned to engage one of the mold cavities in molding relation. Means are provided for moving the molding system between a mold-closed position of engaging mold cores and cavities, and a mold-open position, to permit removal of molded articles from the mold.
In accordance with this invention, the leader pins, which are carried by at least a first of the mold cores, extend through apertures in both of the mold cavities and/or the runner plate. By this invention, the leader pins are long enough to extend the entire mold length, through the other mold core on the opposite side of the mold, in the mold-open position, contrary to the molds of t
Banner & Wticoff, Ltd.
Mackey James P.
Von Holdt John W.
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