US 3264396 A
Description (OCR text may contain errors)
1956 R. 1.. BEESLEY ETAL 3,264,396
METHOD OF INJECTION MOLDING A TOTE CASE 2 Sheets-Sheet 1 Filed Jan. 6, 1964 m mfi T r mafi ve JM mB um Wyn m 3k.
United States Patent METHOD OF INJECTIbN MOLDING A TOTE (ZASE Robert L. Beesley, Saginaw, John W. Mighton, Midland,
and Rudolph H. Matthias, Saginaw, Mich, assiguors to The Dow Chemical Company, Midland, Mich, a
corporation of Delaware Filed Jan. 6, 1964, Ser. No. 335,739
4 Claims. (Cl. 264328) This invention relates generally to tote cases and, more particularly, relates to tote cases particularly suited for handling products such as paperboard and plastic liquid containing packages, and to the method of making such cases.
Prior plastic tote cases fail to provide satisfactory stacking of a plurality of such cases as well as fail to provide a case bottom structure having adequate drainage facilities and yet being of sufiicient strength to endure harsh treatment.
Yet another object of the present invention is to provide a bottom structure for a tote case which is of such a configuration that when it is formed, uniform controlled material distribution in parts can be had even though it be of a generally square or other rectangular configuration.
Briefly then, the present invention thus resides in an improved plastic tote case having all the advantages of the prior cases plus improved stacking characteristics due to an offset shoulder and outwardly extending protuberances. Recessed internal corners are provided in the case which substantially prevent corner fitting of rectangularly shaped cartons. Also comprehended is an improved bottom construction which provides adequate drainage while retaining substantial strength. Co-extensive with the above is a method for forming the bottom construction which method provides for a uniform control of material distribution in the molding thereof.
Yet additional objects and advantages of the present invention, and its numerous cognate benefits and features are even more apparent and manifest in and by the ensuing description and specification taken in conjunction with the accompanying drawing in which, wheresoever possible, like characters of reference designate corresponding material and parts throughout the several views thereof, in which:
FIGURE 1 is a side view of a tote case constructed according to the principles of the subject invention, all sides being substantially alike;
FIGURE 2 is a top plan view thereof;
FIGURE 3 is a bottom view thereof;
FIGURE 4 is an enlarged fragmentary section of two tote cases stacked together, the bottom of an upper tote case stacked upon the top of a lower tote case; and
FIGURE 5 is a bottom plan view of a modified form of tote case having an elongated rather than a square bottom configuration.
Tote case or container is illustrated in FIGURES 1-4 as having a substantially square bottom 11 with side walls 12 extending upwardly therefrom. It is best molded from a lightweight plastic material such as high impact polystyrene or rigid polyethylene, or of other plastic materials having like characteristics. The four side walls 12 of container 10 preferably have a corrugated crosssection formed by undulations 14 to provide increased stacking rigidity, improved control of warpage, minimal moisture condensation, and faster cool-down of the container and contents. Such undulations 14 have been found especially useful in thin walled plastic cases. Corners 15, formed by adjacent side walls 12, are recessed so as to prevent a tight mated fit with corners of cartons, or the like, contained within tote case 10.
3,264,396 Patented August 2, 1966 "ice It is noted that each side wall 12 has hand opening 16 with a lip or raised flange 18 around the periphery thereof to provide a reinforced grip. Formed around the upper periphery of each side wall is a thickened portion 20 which concludes in downwardly extending corner portions 22, the latter containing holes 24 which can be engaged by hooks or the like when the cases are pulled manually or are moved by heavy equipment.
The lower end of each side wall 12 merges into bottom 28 by way of a recessed shoulder portion 26 which gives a generally flat vertical surface 30 with bumps or rounded tapered protuberances 32 located in spaced relationship therealong, as best seen in FIGS. 1 and 4. Protuberances 32 act as spacers juxtapositionable with the inner surface 34 about the top of a stacked tote case of a similar configuration. Preferably, protuberances 32 extend from the surface 30 a distance so as to snugly engage inner surface 34 to give added rigidity to the stacked cases. It can readily be seen that shoulder 26 rests upon the upper peripheral edge 36 of the case therebelow.
FIGURE 3 especially shows that the bottom 18 of tote case 10 is formed about a plurality of cut-outs 38 which provide the improved drainage capabilities of the case, both when it holds containers and when it is in a plant, such as a dairy, being cleaned. The cut-outs 38 are defined by crossed planar portion 40 which is in turn reinforced by downwardly extending ridges 42 along approximately all of its surftce. The T-shaped cross section construction formed by planar portion 40 and downwardly extending rib 42 give improved rigidity. Cut-outs 38 are generally in the form of parallelograms except about the periphery of the bottom where they are in the form of triangles approximately one-half the size of the parallelograms. The crosses formed by planar portion 4t) comprise at least linear diagonals extending generally across said bottom wall between opposite corners thereof.
In forming such a container and its bottom configuration, plastic material is injected into a mold in equal directions from the center of the bottom through a gate (not shown). The location of the gate is defined in FIG- URE 3 by central aperture 44 which is surrounded by thickened peripheral flange 46. When a case is injection molded, plastic flows from the center portion, under pressure, in a flow pattern substantially as defined by surfaces 40' and ribs 42, which pattern makes the distance from the orifice of the gate to peripheral points around the sides, such as 48, 50, 52, etc., the same. Thus, the distance through which the material must flow, i.e. from the gate to the corners or the side walls, is the same in every instance. Such uniform controlled material distribution in molded cases having square or rectangular bases eliminates the prior problems caused by warping, poor weld lines, packing stress, and all the other inherent characteristics in prior art designs.
That an elongated rectangular base for a'tote case can likewise have uniform material distribution when molded through a central gate is illustrated by FIGURE 5. For example, here the flow distance from central aperture 54 of case 56 to the corners, such as corner 58, is the same as the flow distance to any point on the sides, such as to points 6%) or 62, the distance being defined by ribs 64. Ribs 64 in this instance define cut-outs 66 in the shape of parallelograms about the center and triangles about the periphery of the bottom.
While certain representaive embodiments and details have been shown for the purpose of illustrating the invention, it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention.
Accordingly, What is claimed as new is:
1.- The method of forming a molded plastic tote case 7 having a rectangular bottom, said method comprising the step of injecting thermoplastic material from the center of said bottom along a plurality of flow lines which cross one another and are of the same length to the periphery of said bottom, whereby uniform controlled material distribution is maintainedv 2; The method of claim 1 wherein said flow lines are step of injecting thermoplastic material from at leasta point in a plurality of intersecting flow lines which is substantially equidistant from the furthermost extents said material must travel through said flow lines, said flow lines arranged to define a plurality of like parallelograms in rows.
having a rectangular bottom, said method comprising the References: Cited by. the Examiner.
UNITED STATES PATENTS 3/1940 Tegarty 1830 9/1947 Stacey 1842 1 12/1956 Knieriem 220-97 8/1958 Pollard 264-328 10/1961 Lovell; -2 23097 10/1961 Gustafson 220 10/1963' de Chelbor 220-21 4/ 1964 W0rmer 220-21 5/1964 Peters 264--328 12/1964 Herter 264-328 1/1965 Box- ,22021 FOREIGN PATENTS 8/1960 France.
1/ 1957 7 Germany.
ROBERT F. WHITE, 'Primary Examiner.
GEORGE E. LOWRANCE, Examiner.
R; B. MOFFITT; Assistant Examiner.