Plastic article or earthenware shaping or treating: apparatus – Distinct means to feed – support or manipulate preform stock... – Female mold type means
Reexamination Certificate
2001-10-16
2004-03-02
Davis, Robert B. (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Distinct means to feed, support or manipulate preform stock...
Female mold type means
C425S125000, C425S127000, C425S129200
Reexamination Certificate
active
06699028
ABSTRACT:
INTRODUCTION TO THE INVENTION
The present invention relates generally to a molded article having an insert embedded therein, as well as an apparatus and method for making the same.
It is known to provide shoe insoles with inserts located in recesses thereof. The material of the insert generally has different characteristics from the material of the remainder of the insole to provide a specialized effect, such as a greater degree of cushioning under specific portions of the foot.
Generally, such inserts have been attached within recesses or pockets at the lower surface of a formed insole, such as by means of adhesives. However, the use of an adhesive provides various disadvantages. Specifically, it is difficult to maintain the entire insert in full contact with the insole when securing the same. This becomes even more evident as the size of the insert increases. There is thus a problem with product quality and consistency. Further, in some cases, because of the nature of materials used to form the insole, it is difficult for the adhesive to adhere to the insole. This adherence problem can also be due to the presence of mold release agent residues from the molding operation. As a result, specialized glues are required. Also, the operation requires additional labor and handling to glue the inserts, thereby increasing costs.
Several attempts have been made to mold inserts directly into insoles. Examples are described in U.S. Pat. Nos. 4,674,204 and 4,910,886. However, a problem frequently occurs with staining of the inserts from the molding material. In some cases, because of the porosity of the insert and the large pressure applied to the liquid polymer substances during the molding operation, the liquid penetrates into the insert. This results in an unsightly, non-uniform or irregular staining of the insert. The penetration of the molding polymer into the insert also changes the rigidity of the insert, that is, making it harder, and thereby changing the performance thereof.
As mentioned above, fluid polymer-forming materials sometimes tend to flow into the porous structure of the inserts due to the high pressure in the cavity. As an example, there is a chemical reaction with liquid urethanes (preferred materials for making many types of insoles), which releases a gas such as CO
2
. This chemical reaction causes the urethane components to expand from 120% to 200%-300% of the original volume of the liquid urethane. Since the mold is a closed mold and since the liquid urethane expands therein, there is a large increase in internal cavity pressure, so that a large external pressure must be applied to maintain the mold in a closed condition. Therefore, there is a pressure drop of about 15 to 20 psig (1.03 to 1.38×10
5
Newton/meter
2
) across the inserts, that is, from the upper surfaces of the inserts to the lower surfaces thereof. Also, the inserts are open to atmospheric pressure at their sides. Because of this, the liquid urethane flows into the cells of the porous structure of the inserts, which result in the inserts becoming more rigid and less resilient, while also causing the aforementioned staining.
In addition to the penetration through the insert, the liquid urethane tends to leak around to the underside of the insert during the molding operation, between the insert and the surface of the mold, causing a thin overcoat layer on the exposed surface of the insert around the edges of the insert. Any seals which are provided to prevent migration of the liquid urethane around the insert during the molding operation have not been very successful, and still permit this type of overflow to the underside. A reason for this overflow is the large pressure applied to the liquid urethane during the molding operation. As a result, this overflow layer provides an unsightly visual defect on the bottom surface of the insole. Because such overflow layers are not uniform, the insoles have an appearance of poor quality.
There is a further problem with such molded inserts. Specifically, it is difficult to maintain the position of the inserts during the molding operation as liquid polymer components are introduced into the mold, since the inserts tend to float on the liquid polymer.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a molded article having an insert embedded therein, as well as an apparatus and method for making the same, that overcomes problems with the aforementioned prior processes.
It is another object of the present invention to provide a shoe insole having a properly positioned insert embedded therein, as well as an apparatus and method for making the same, in which there is no staining or overflow layer on the inserts.
It is still another object of the present invention to provide a shoe insole having an insert embedded therein, as well as an apparatus and method for making the same, in which a retainer with an upper lip is provided around the periphery of each insert during the molding operation to provide a seal that prevents flow of the liquid urethane around the peripheral edges of the insert and also properly positions the inserts into the insert cavity of the insole.
It is yet another object of the present invention to provide a shoe insole having an insert embedded therein, as well as an apparatus and method for making the same, having an elevator mechanism that permits the inserts to be inserted into the dammed area and under the lip and thereafter clamps the peripheral edges of the inserts between the elevator mechanism and the lip to provide a seal against the flow of molding material under the insert.
It is a further object of the present invention to provide a shoe insole having an insert embedded therein, as well as an apparatus and method for making the same, in which a barrier layer may be provided on a permeable insert in order to prevent penetration of the liquid molding material into the insert during the molding operation.
It is a still further object of the present invention to provide a shoe insole having an insert embedded therein, as well as an apparatus and method for making the same, that is easy and economical to make and use.
In accordance with an aspect of the present invention, an apparatus for making a molded article containing an insert includes an upper mold half and a lower mold half for mating with the upper mold half to provide a mold cavity therein. Either mold half can include a recess, an elevator opening in a lower portion of the recess, and an inwardly directed lip at an upper portion of the elevator opening. An elevator mechanism is provided which includes a lifter for supporting an insert to be secured to the article during a molding operation, and a lifting arrangement for raising and lowering the lifter through the elevator opening such that a peripheral edge of the insert supported on the lifter is clamped between the lifter and the lip when the lifting arrangement raises the lifter.
Any lifter actuation mechanism can be used. One such lifter mechanism includes a base positioned below the lower mold half, and a cylinder mounted to the base and including a movable piston rod connected with the lifter for raising and lowering the lifter. The base includes a recess for mounting the cylinder.
In one embodiment, a retainer is removably connected to the lower mold half within the elevator opening. The retainer includes a dam flush with and removable from an inner wall defining the elevator opening, as well as the inwardly extending lip which is connected to an upper end of the darn. The retainer further includes a lower outwardly extending connector connected with a lower end of the dam and removably secured to a lower surface of the lower mold half.
In another embodiment, the lifting arrangement includes an upper slide plate having a lower inclined cam surface, the lifter being connected to the upper slide plate; a lower slide plate having an upper inclined cam surface in contact with the lower inclined cam surface; and a moving arrangement for sliding the lower slide plate relative to t
Davis John W.
Fisher Randall K.
Noble, Jr. Joseph J.
Davis Robert B.
Franks Robert A.
Schering-Plough HealthCare Products Inc.
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