US3268144A - Thermoplastic container with side wall and rim strengthening characteristics - Google Patents

Description

g- 1956 T. N. GAUNT 3,268,144

THERMOPLASTIC CONTAINER WITH SIDE WALL AND RIM STRENGTHENING CHARACTERISTICS Filed March 23, 1964 INVE NTOR: Thomas Norman Gaunt United States Patent 3,268,144 THERMOPLASTIC CONTAINER WITH SIDE WALL AND RIM STRENGTHENING CHARACTERISTICS Thomas Norman Gaunt, Leeds, England, assignor to Illinois Tool Works Inc., Chicago, Ill. Filed Mar. 23, 1964, Ser. No. 354,170 Claims priority, application Great Britain, Mar. 25, 1963, 11,641/63; Nov. 16, 1963, 45,342/63 1 Claim. (Cl. 229--2.5)

The present invention relates to trays or containers formed from thermoplastic material having strengthening and rigidifying characteristics.

One of the inherent difficulties of trays or containers formed from thermoplastic sheet material is their lack of rigidity which tends to make such trays or containers difficult to handle during filling, sealing or normal use, and therefore, it is a principal object of the present invention to provide a new and improved form which will overcome or at least improve the lack of rigidity inherent in such containers.

According to the invention trays or containers of suitable thermo-plastic material are characterised by being of dished form whose side walls taper outwardly and are radially inwardly bowed from the base towards the upper portions. The side walls terminate in a rim area which is first outwardly extended to form a short ledge, then substantially upwardly to form a vertical portion and then substantially horizontally, finally being displaced downwards to terminate in a further substantially vertical portion. Alternatively, the downwardly disposed portions terminate in any suitable or desired shape or configuration.

In order that the invention may be fully and clearly comprehended, the same will now be described with reference to the accompanying drawings wherein there is illustrated in FIGS. l cross-sectional views of trays or containers according to various different embodiments of the present invention.

The trays or containers are manufactured from suitable thermo-plastic sheet material such as polystyrene, P.V.C., polythene, polypropylene and analogous plastics substances. The manufacturing technique employed may include any suitable well known pneumatic or mechanical forming process or combination of the same for producing a tray or container of the type now to be described.

Referring now to the drawings, it will be observed that the side walls 1 of each tray or container of the present invention are radially inwardly bowed as they proceed upwardly from the base or bottom 2 towards the upper portion or extremity of the side walls. The side walls terminate at the upper end thereof in a rim area which is first outwardly extended relative to the upper portion of the side walls to form a short ledge 3 which is displaced through an angle of at least eighty degrees, and preferably more than ninety degrees relative to the side walls 1.

The remaining extended portion is further distorted or bent upwardly approximately through an angle of 90 to form a substantially vertical part 4 and thereafter outwardly in a horizontal manner to form a ledge 5 whose ultimate extremity is displaced downwardly to form a skirt portion at 6.

The above described construction of the rim area in the container of the present invention is clearly illustrated in FIGS. 1-5 of the drawings. Each container shown is provided with portions 3, 4, 5 and 6 which is peculiar to all examples of the present invention by which trays or containers with a parametrical strengthening or stabilizing bead of inverted channel-shaped cross-section may be provided. This can be readily depicted in FIGS. 1-2 of the drawings wherein each of the containers are provided with portions 3-6, the difference between these two embodiments being that in the FIG. 2 embodiment, the corners of the tray or container are radiused to a greater degree than in the FIG. 1 embodiment. In some cases, it may be desirable to extend portion 6 of the rim area, and this may be effected in various ways. For example, the extremity of the portion 6 may be flared outwardly and downwardly as shown in FIG. 4 or it may include a horizontally extending shelf portion 7 as illustrated in FIG. 3, or may terminate in an upwardly curved portion 8 such as shown in FIG. 5. Other variations are, of course, possible within the scope of the present invention.

In every instance, the walls of the container are radially inwardly bowed from the area of juncture 9 with the bottom or base 2 to the rim area of the container. This will not only impart rigidity to the side walls of the container to aid, for example, in preventing or at least hindering side wall bulging due to product overloading, but will also cooperate with the rim area in imparting increased strength thereto. In this latter regard, it is important that the channel-shape rim area of the container is provided with a dimensional extent such that the rim area is capable of deriving both lateral and longitudinal support from the radially inwardly bowed side walls 1 so that increased strength is imparted to the rim area as well as the side walls of the container. The area of juncture 9 of the side wall with the bottom or base 2 of the container is radially outwardly bowed to also aid in imparting rigidity to the side walls. Additionally, this radially outwardly bowed portion 9 has an outer peripheral dimension greater than a predetermined area of a portion of the radially inwardly bowed side walls immediately thereabove to provide interference between such portions on similarly configured containers when stacked in telescopic relationship, the stacking depicted by the partial phantom and full line container in FIG. 4. The relative dimensional relationship between the radially outwardly bowed portion and the radially inwardly bowed side wall portion immediately thereabove also afiords centralization between adjacent containers as they are stacked and prevents contact between the radially inwardly bowed portions of adjacent containers. This latter feature is particularly important in those instances where the exterior side wall surfaces of the containers are printed since it acts in the manner of an anti-rub feature to protect printed indicia on the side walls of the container.

Either the base or the walls or both base and walls may be shaped or patterned in any manner desired, such, for instance, as is set forth in our co-pending patent application No. 11,640 of 1963, or the said portions may have plain or unbroken surfaces.

Although specific embodiments have been shown and described, it is with full awareness that many modifications thereof are possible. The invention, therefore, is not to be limited except by the prior art and by the spirit of the appended claim.

I claim:

A thin-walled one-piece seamless container formed from thermoplastic sheet stock material, comprising peripherally continuous side wall means of substantially uniform cross-section extending upwardly and outwardly from a bottom wall and terminating in a rim area adjacent the open upper end thereof, said side wall means in the area of juncture with said bottom wall being first radially outwardly bowed and then radially inwardly bowed as it proceeds upwardly therefrom until it terminates in said rim area, said radially outwardly bowed portion having an outer peripheral dimension greater than a predetermined area of said radially inwardly bowed portion immediately thereabove to provide interference between such portions on similarly configured containers when stacked in telescopic relationship, said radially outwardly bowed portion serving as a pilot means in mm tralizing containers as they are stacked and aiding in preventing contact between the radially inwardly bowed portions of adjacent containers, said rim area including a shelf portion. radially outwardly directed from said side wall and being disposed therefrom by an included angle of at least eighty degrees, said rim area further including a substantially vertically extending portion integrally joined to said shelf portion at its lower end and to a substantially horizontally extending portion at its upper end, said rim area terminating in a skirt portion depending from said horizontally extending portion, at least the major portion of which is generally parallel to said vertically extending portion whereby to provide a parametrical strengthening bead of inverted generally channel-shaped cross-section,

each portion of said channel-shaped rim area having a dimensional extent such that said rim area is capable of deriving both lateral and longitudinal support from said radially inwardly bowed side wall in imparting increased strength to said rim area.

References Cited by the Examiner UNITED STATES PATENTS 7/ 1877 Hamilton 220-74 7/1932 Hart et a1 2292.5 1/ 1934 Shermann 2292.5 3/1955 Cook 2292.5 X 11/ 1957 Emery 2292.5 9/ 1958 Dingeldein 22097 X 2/ 1959 Gunn. 1/ 1961 Canfield et al 229--3.5 X 2/1964 Fotos 220--97 X 5/ 1964 Whiteford 2292.5

FOREIGN PATENTS 8/1959 France.

JOSEPH R. LECLAIR, Primary Examiner.

FRANKLIN T. GARRETT, Examiner.

D. T. MOORHEAD, Assistant Examiner.

Images