Static molds – Mold including core and means to remove core
Reexamination Certificate
2000-03-22
2003-11-25
Mackey, James P. (Department: 1722)
Static molds
Mold including core and means to remove core
C249S096000, C249S142000, C249S177000
Reexamination Certificate
active
06651949
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to method and apparatus for casting a gasket into a cast member and more particularly, to a gasket and a positioning ring upon which the gasket is force fittingly mounted and method and apparatus for casting same.
BACKGROUND OF THE INVENTION
It is conventional in septic tanks, as well as other cast members, such as concrete structures, to provide openings, within the cast member to accommodate the insertion of a pipe therethrough.
Septic tanks, as well as other similar structures, are cast in a mold assembly, typically comprised of inner and outer mold members which respectively define the interior and exterior walls thereof.
In one conventional casting operation, the outer walls or jackets defining the outer periphery of the cast member are swingably mounted near their lower ends. Preparatory to casting, the pivotally mounted outer jackets are swung to an upright, vertical (i.e., “closed” ) position in readiness for receiving the cast material.
Cast members, such as septic tanks are typically four-sided, rectangular-shaped members having at least one opening provided one or more of its side walls.
One technique presently being utilized to define the opening in a side wall of the cast member is to fixedly secure a metal or plastic mandrel to the inner wall of an outside jacket A one-piece pipe seal is releaseably mounted upon the mandrel, whereupon the outer jacket is swung to the upright vertical position in readiness for pouring of the cast material. The pipe seal has an outer peripheral flange, which is anchored within the cast material.
After the cast material has set, the outer jackets are opened to remove the cast member. The mandrel pulls away from the pipe seal, which is retained within the sidewall of the cast member.
The pipe seal typically has an integral central portion which seals the side wall in the event that no pipe is to be inserted through that side wall and further is provided with circular sections which may be easily torn away to form an opening for accommodating two, three or four inch pipes, for example.
A pipe of the suitable diameter is inserted into the opening of the pipe seal. The pipe seal is formed of a substantially non-resilient plastic material and, at best, forms what is referred to as a “dirt seal” with the pipe, enabling undesirable materials to leach into the cast member, as well as, allowing undesirable materials within the cast member to seep out.
In addition, the pipe quite frequently is utilized to support internal components, such as baffles and filter systems which, due to their significant weight, as well as the weight of the pipe itself, cause the “dirt seal” to further weaken and deteriorate, enabling even greater seepage of undesirable materials through the “dirt seal”.
BRIEF DESCRIPTION OF THE INVENTION
The present, invention is characterized by comprising method and apparatus for providing a water-tight seal for cast members, such as septic tanks and the like, wherein the water-tight seal is obtained through the use of an inexpensive and yet rugged gasket which is highly, effective in providing an excellent water-tight seal between the opening and a pipe inserted through the gasket and which further assures highly accurate positioning of the gasket within the cast member.
The present invention comprises a resilient, compressible rubber or rubber-like gasket of annular shape having a main body portion with anchoring means extending radially outwardly therefrom and joined to the main body portion by a flexing portion which is adapted to bend upon insertion of a pipe enabling one side surface of the main body portion to make surface contact with the pipe over a significant area to provide a good water-tight seal.
In addition thereto, water-energizing pockets are provided as is described in detail in U.S. Pat. No. Re 34,787 and pending application Ser. No. 08/947,755, filed Oct. 9, 1997, now U.S. Pat. No. 5,997,006 issued Dec. 7, 1999, which patents are assigned to the assignee of the present application, the teachings thereof being incorporated herein by reference thereto. The water energizing pockets further enhance the water-tight seal, as is described in detail in the aforementioned U.S. Patent and co-pending application.
An annular-shaped plastic mandrel has a radially, inwardly directed annular flange or “hook” portion which snaps over the gasket and locks the gasket in place on the mandrel. The plastic mandrel serves as a means for defining the opening within the cast member along the interior side of the member.
The gasket assembly which is now comprised of the interlocked gasket and plastic mandrel are placed onto the metal or plastic outer, mandrel, which is typically welded or bolted to the interior surface of the swingably mounted, outside jacket. The jacket is then moved to the upright (“closed”) position preparatory to the casting operation, whereupon the cast material is poured into the mold. The side of the plastic mandrel opposite the hook portion joined to the gasket engages the interior wall of the inside jacket and thereby cooperates with the metal or plastic outer mandrel to properly position and space the gasket between the interior walls of the inner and outer mold members.
When the cast material (i.e., concrete) is cured, the outside jacket is swung away from the vertical position whereupon the outside jacket and outer mandrel are stripped away from the gasket assembly, leaving the gasket and plastic mandrel anchored within the cast member. The, plastic mandrel is provided with a left-hand portion of reduced diameter relative to the portion adjacent. thereto, forming a shoulder which locks the plastic mandrel within the cast member due to the cast material filling in the portion of reduced diameter and resting against the shoulder to prevent the plastic mandrel from being dislodged from the cast member. Although the hook portion of the plastic mandrel is maintained within one of the water energizing pockets, the water energizing pocket, which is effective upon insertion of the pipe, is on the opposite side of the plastic mandrel so that the plastic mandrel does not in any way reduce the effectiveness of active water energizing pocket.
In one preferred embodiment, the plastic mandrel may be fitted with a hollow, annular-shaped pipe stop which is snap fitted to the end of the plastic mandrel remote from the gasket. The pipe stop extends radially inward by a distance sufficient so as to be engaged by the end of a pipe inserted into the gasket causing the pipe to rest against the stop and thereby control the depth to which the pipe is inserted into the opening in the cast member. As is described in detail in the aforementioned U.S. Pat. Nos. Re 34,787 and 5,997,006, the gasket, together with its water energizing pocket provides an excellent water-tight seal.
As another preferred embodiment of the present, a cover plate may be snap-fitted over the end of the plastic mandrel opposite the hook shaped end, providing a water-tight closure for the cast member. The cover plate is formed of a suitable plastic material which may be cut away at some future time to provide for insertion of a pipe.
Although the outer jacket swings away from the cast member after it has been cured, moving along an arcuate path, the gasket is sufficiently yieldable to enable the outer jacket and outer mandrel to be readily and easily stripped from the gasket without any undesirable displacement, due to the resiliency and compressibility of the gasket. The plastic mandrel further provides the function of assuring proper placement and positioning of the gasket between,the inner and outer mold members, the need for providing a mandrel which extends all the way to and engages the inner mold member, is thus eliminated.
In still another preferred embodiment of the present invention, a reusable mandrel is secured to the swingable jacket of a mold assembly. The mandrel is comprised of a slightly tapered inside portion and a more severely tapered outside portion separated by a gap which forms a rec
Kelly James A.
Westhoff James A.
Heckenberg Donald
Mackey James P.
Poly-Tec Products, Inc.
LandOfFree
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