Conveyors – chutes – skids – guides – and ways – Chutes
Reexamination Certificate
1998-03-27
2001-03-06
Ellis, Christopher P. (Department: 3615)
Conveyors, chutes, skids, guides, and ways
Chutes
C193S022000, C193S037000
Reexamination Certificate
active
06196370
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to an apparatus used to transport, convey, or move various objects, such as packages, from one location to another; and, more particularly, to coatings or liners for the surfaces on which the objects are transported, conveyed or moved; and a method of applying such coating or liner to such surface.
2. Description of the Prior Art
In the package shipping industry, the package is processed for trans-shipment using a stationary chute where the package is caused to be moved along by an external force, such as gravity. The chute may come in various sizes and shapes, such as an inclined slide with a stopper wall or horizontal plane at the bottom thereof, a spiral channel going from one floor to another, a circular angled flat surface, etc. The term “chute” is defined elsewhere herein. Almost every package shipping and processing station has one or more chutes which are used in the processing of the packages.
The most troublesome problem in the package shipping industry has been the continual pile-up or build-up of the packages in the chutes. The packages inevitably tend to stick and/or bridge, and cause a back-up of the packages and a shut down of the conveying line. This problem may be caused most often by defective design of the chutes as well as by such factors as humidity (e.g. the packages are wet) and the condition and/or composition of the packages (e.g. “shrink wrapped” plastic coating). There is poor compatibility between the chute surface and the packages. But, due to cost and other considerations, there has been very little change in the structural design of the chutes. Thus, in the prior art, the problem of package build-up, bridging, sticking, back-up, and the like, has been approached in an ad hoc manner as to solutions for such problem. Some of these approaches are as follows, none of which are satisfactory.
The most obvious solution and which has been the most expensive has been for the operator to stop the transporting line, and then go to the chute location where there is bridging, etc, and using a pole or other ad hoc tool, knock the packages around until the back-up problem is solved. Unfortunately, many of the problems occur in hard to reach places. Thus, the human operator is often injured while trying to solve the problem. This increases considerably the Workman's Compensation rate, injury to the worker, and conveying line down time. Also, recent tightening of OSHA rules makes this solution outdated. In other words, this ad hoc solution is no longer feasible.
Also, when the packages are “wet” or “shrink wrapped”, the transport surface of the chute was sprayed or painted with graphite paint or paraffin wax partially diluted with water. However, this solution was not satisfactory because of the costs involved and because of the contamination caused to other packages and other parts of the conveying system, such as to moving conveyor belts which would become coated with the wax and/or graphite and require frequent and costly replacement. Also, this solution is really no solution since the wax and/or graphite would be effective at most for only a day or so because most of the coating would tend to stick to the package and be taken away thereby. In this type of solution, we can also include use of oils and other similar material, which also have the same problem.
Another solution attempted in the prior art was covering the transporting surface with a sheet of UHMW (ultra high molecular weight) polyethylene. Although the polyethylene layer appears to be “slick”, in point of fact, it is inherently non-stack in effect. The material tends to abrade in a manner similar to a sheet of plywood which may sliver and itself thereby cause the packages to bridge and stick. Once abraded, the UHMW polyethylene layer's coefficient of friction and surface energy will begin to have an adverse effect on movement of the package placed on its surface. Also, disadvantageously, the process of applying this UHMW layer is time consuming because it must be cut, bevelled, drilled, and countersunk with screws. The cost of installation is thus almost prohibitive. Accordingly, this solution is not satisfactory.
A further solution was recently suggested, but was found to have too many disadvantages to be economically feasible. This was to make the chutes of molded fiber glass with a high build epoxy coating on the conveying surfaces. It was discovered that such chutes factured easily, were difficult to repair, were of brittle material, and had inadequate release properties. Thus, rather than solve the problem of build up, this type of chute caused almost the same problem of build-up and accordingly, the problem was not solved satisfactorily.
Thus, the prior art had not yet satisfactorily resolved the problem of package buildup, bridging, sticking, etc., in chutes.
SUMMARY OF THE INVENTION
Accordingly, an object of the invention is to overcome the aforementioned and other problems, deficiencies, and disadvantages of the prior art.
Another object is to provide a chute for transmission, transport, conveying or moving objects, such as packages, wherein the transport surface (which may otherwise be called “substrate” before installation of the coating or liner) of the chute has been coated or attached thereto a liner comprising a skived PTFE film or layer (“PTFE” is otherwise known as polytetrafluoroethylene, and to the layman, such composition may also be known as TEFLON in various forms). The term “PTFE film or layer” includes polymerized and/or copolymerized tetrafluoroethylene. Also, the transport surface or substrate may be flat or textured.
Another object is to provide such a chute wherein both the horizontal and non-horizontal surfaces are coated with or has attached thereto a liner comprising a skived PTFE film or layer.
A further object is to attach the skived PTFE film or layer to the transport substrate by use of a pressure sensitive acrylic adhesive which substantially intimately bonds the film to the substrate, so that the substrate and film act as a unitary structure in holding and moving packages in a non-stick manner.
Another object is to provide a chute wherein the surface contaminants are first mechanically removed, then cleaned with use of a non-soap, non-surfactant cleaner, then, rinsed, dried and then, the skived PTFE film is bonded to the chute surface with use of an adhesive, most preferably an acrylic adhesive, wherein the adhesive is applied by use of pressure on the PTFE film.
A further object is to provide a chute wherein “high spots” in the transport substrate or surface are smoothed and the PTFE film is attached to the surface or substrate surrounding the “high spots”.
Another object is to provide a method of applying a liner comprising a skived PTFE film or layer onto a transport surface of a chute used to convey packages, wherein the surface is first prepared to smooth and clean the surface, and then cleaned with a non-soap, non-surfactant cleaner, then, rinsed, and then dried, and then, a pre-cut strip of skived PTFE film having a pressure sensitive adhesive layer bonded thereto is attached to the surface of the chute with the adhesive layer wherein the strip has its longitudinal direction disposed to be parallel to the direction of travel of the packages.
A further object is to provide a diamond shaped piece of PTFE film or layer in repairing damaged areas of priorly installed PTFE film on transport surface.
A still further object is to burnish edges of adjacent strips of PTFE films having a gap therebetween to thereby reduce the gap distance.
Another object is to sandpaper edges of the PTFE film to create gradual surfaces thereof and prevent “catching” of the edges by the packages traveling on the PTFE film surface.
A still further object is to provide a method of applying a skived PTFE film or layer to a chute surface or substrate, wherein the skived film or layer of PTFE having a reverse surface thereof coated with an acrylic or other adhesive is exposed gradually along its width di
Beale Scott Andrew
Ritter James Michael
Crawford Gene O.
Ellis Christopher P.
Heslin & Rothenberg, P.C.
Tonoga Limited
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