US 3820684 A
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United States Patent 1191 Harrison June 28, 1974  PLASTIC CUP 2,988,258 6/1961 Witze 229/15 B 3  Inventor: James M. Harrison, Fort Worth, 375954 M968 Hohkmcn 220/97 Tex.
73 A C C C t C F 11 Primary Examiner-George E. Lowrance sblgnee gj mer orpora O Attorney, Agent, or Firm-Kinzer, Plyer, Dorn &
McEachran  Filed: Oct. 13, 1972  Appl. No.: 297,477
Related US. Application Data  1 ABSTRACT  Continuation of Ser. No. 107,968, Jan. 20, 1971,
abandcned- This is concerned with a so-callled foam cup of the V. type made of foam polystyrene or the like intended to  us. Cl. 206/520, 229/L5 B be used in Vending machines for either hot or cold ] ll lt. Cl 365d 21/02, B65d l/l6 ids and having a differential taper between the Sub  F'eld of Search 220/97 97 831 9 F; faces on the outside and inside of the side wall so that 229/15 B the surfaces of such cups when nested will contact only in a minute or highly restricted area, if at all, thus  References Cited UNITED STATES PATENTS 9/1957 Smucker 220/97 C rendering them suitable for use in vending machines.
2 Claims, 3 Drawing Figures PLASTIC CUP SUMMARY OF THE INVENTION This invention is concerned with a drinking cup to be used in vending machines, although it may have many other uses, and is specifically concerned witha cup made from foampolystyrene plastic beads.
A primary object is a plastic drink'cup which, when nested with similar such cups in a stack, will have clearance between the walls thereof.
Another object is a cup of the above type having a non-uniform wall section.
Another object is a cup of the above type in which the internal taper of the wall does not match the external taper.
Another object is a cup of the above type that, when nested with similar such cups, will contact only in a minute or highly restricted area.
Another object is a cup molded from expandable polystyrene that will successfully vend in automatic dispensing equipment.
Another object is a cup specifically constructed to minimize the drag or friction between the inner surface of one cup and the outer surface of another.
Another object is a cup produced from a set of molds with a different taper on the male portion of the mold from that of the female portion.
Other objects will appear fromtime to time in the ensuing specifications and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of such a cup;
FIG. 2- is a top'view of FIG. 1; and
FIG. 3 is a section along Line 3-3 of FIG. 2 with two cups nested.
DESCRIPTION OFTHE PREFERRED EMBODIMENT agent which might be methane, butane, etc. The beads are introduced into a closed mold and, when heat is applied, the expanding agent expands tending to vaporize which causes the beads, which have been softened by the heat, to expand so that they fuse with one another and completely fill the bowl resulting in a homogeneous, dimensionally-stable lightweight cup.
Cups made from foam polystyrene are commonly referred to as foam cupsfare old and well-known and have long been used. But such cups have never successfully been used in vending machines due to the fact that the surfaces or interface between one cup and another in a stack tend to adhere or cling to one another. This may be caused by a number of factors, such as static electricity, vacuum, molecular attraction, surface tension, and what have you. In any event, a stack of such cups in a vending machine will resist proper vending.
The lowest such cup in the stack will refuse to drop which will cause difficulty and improper functioning of the machine.
I In the cup shown in the drawing, the side wall 12 has an inner surface 20 and an outer surface 22. Upon close inspectionit will be noticed that the taper of these surfaces do not match. This is to say that the included angle of the inner surface 20 is slightly greater than the included angle of the outer surface 22. For example, the inner surface 20 might have an included angle of 815 and the outer surface might have an included angle of 8. The result is that the wall thickness of the cup wall will be greater at the bottom 18 of the cup than it as the lip 16. For foam polystyrene cups to be used in vending machines, a differential between the included angles of 15' has been quite satisfactory with the wall thickness at the lip 16 being approximately 0.032 inches. The precise overall. dimensions of such a cup are not critical, but representative dimensions might be a cup that is 3 /2 inches in height, 2% inches in the diameter at its free, open upper end, l /8 inches in diameter on the bottom or closed end, and on the order of 0.035 inches in wall thickness at the bottom. Such a cup might weigh on the order of 3.0 grams.
It has been found convenient 'to provide a stacking shoulder 24 in the bottom which may take the form of a-thickened portion 26, thickened inwardly and merging into the bottom wall 18 by a short tapered surface 28 which may match the taper or included angle of the inner surface 20 of the main portion of the side wall.
The diameter of the bottom, designated 30 in FIG. 3, should be no greater than the maximum diameter, designated 32, of the stacking shoulder 24. The point is that the bottom surface 18 should hit the angular surface 24 either before or at the same time that the outside tapered surface 12, at the small end in area 34, hits the inner tapered surface 20 where it merges or joins or intersects the angular shoulder 24, this area being designated 36 in FIG. 3. This has at least two advantages. First, a direct columnar load can be carried through the areas 26 from one to another to take the axial loading applied to a stack and, second, a spacing, designated 38, will exist between the side walls of adjacent cups. Note that this space increases in width upwardly.
The use, operation and function of the invention are as follows.
A lightweight foam polystyrene cup is provided which has an inner and an outer surface on its side wall out of contact with each other when the cups are nested. This is accomplished by having an internal taper inside the cups that differs but does not match the external taper. Preferably the inner taper has a greater included angle than the external taper so that the cup is thin at the lip and wider at the bottom. When two sets of cups from a similar mold are nested one inside the other, the inner surfaces will contact at the bottom in a very small or highly restricted area, if at all. The nonuniform wall thickness can be acquired by molding the cup in a mold where the taper on the male portion of the-mold is different from that of the female portion. This can be easily accomplished in molding foam polystyrene where the beads are charged in a suitable manner into a closed mold and heat is applied to expand the beads and fuse them. 7
For vending machines the cup should be extremely lightweight, very thin wall, and also sfficiently sturdy to be dropped from a stack, filled with coffee and handled.
Since the internal taper has a greater included angle than the external taper, nesting could create a problem since the exterior of one would tend to wedge in the interior of another. But this can be prevented by a stacking rim or shoulder which is dimensioned to contact the bottom of the next cup before the two tapers either contact or wedge. In a cup where the side wall at the lip is 0.035 inchesthick with an external taper of 8 and an internal taper of 815 the actual height of the shoulder should be on the order of 0.260 inches so that the bottom will not wedge in the next cup but will contact the shoulder first.
While the preferred form has been shown and described and several modifications have been suggested, it should be understood that suitable additional modifications, changes, substitutions, and alterations may be made without departing from the inventions fundamental theme.
1. An integral unitary thin wall cup made of foamed polystyrene beads having a generally tapered side wall with an integral bottom wall closing the small end and the large end being open and providing a free edge lip, the side wall having inner and outer uniform tapered surfaces with the taper of the inner surface having a slightly greater included angle than the taper of the outer surface so that the side wall is thinner, in cross section, toward the lip than it is toward the bottom wall, an offset shoulder in the inner tapered surface adjacent the bottom wall functioning as a continuous stacking annulus when a plurality of such cups are nested in a stack, the diameter of the inner tapered surface, where it intercepts the offset shoulder, being no less than the outer diameter of the bottom wall.
2. The structure of claim 1 further characterized in that the wall of the cup is approximately 0.035 inches thick, the cup is approximately 3V2 inches high, and
weighs approximately 3.0 grams.