Container And Closure

Abstract

A thin wall plastic container having a rim-type nesting ring which also serves as a lid seat and includes protuberances spaced about the rim for centering a paper tab-type lid so that it may be snapped in place into the lid seat merely by the application of downward pressure.

Description

This invention relates to thin wall disposable plastic containers and more particularly comprises a container having a combination lid seat and nesting ring with centering means provided on the rim for orienting a paper tab-type lid.

Thin wall plastic containers having lid seats adjacent the container rim are often provided with a pilot above the lid seat to center the lid so that it can be snapped into the lid seat merely by the application of downward pressure on the lid. The pilot prevents the lid from shifting laterally to one side or the other so that proper alignment is always maintained. This is particularly true with containers designed to receive paper tab-type lids.

In the so-called combination rim-type stacking ring and lid seat arrangements, flat paper tab lids are not commonly used, particularly with automatic handling equipment because of the lack of means for dependably aligning the thin paper lids with the container so that they can be readily snapped in place. The coverall type of lids ordinarily used with such containers in automatic handling equipment possess enough axial height at their own rim to guide the lid in place so as to establish and maintain proper alignment. The paper tab lids, however, do not have the axial extent of a coverall lid because the paper tab lid lacks any skirt or vertical wall for this purposes. Rather, the paper tab lid is merely as thick as the stock from which it is made, and it provides no readily available means for centering the lid by engagement of its periphery. Therefore, paper tab lids are not commonly used with such containers when automatic handling equipment is employed.

One object of this invention is to provide a ready means for centering a paper tab lid on the rim of a container.

Another object of this invention is to provide guide means on the container rim for centering a lid and which guide means do not interfere with the container use.

To accomplish these and other objects the thin wall plastic contaainer of this invention includes a combination lid seat and rim stacking device having an upper shoulder and a lower shoulder, and protuberances are provided about the upper shoulder, which shoulder is also the container rim, for centering a paper tab lid that is to be used with it.

In the drawing:

FIG. 1 is a fragmentary cross sectional view of a container constructed in accordance with this invention and showing in broken lines the location of the lid before it is snapped in place;

FIG. 2 is a fragmentary plan view of the combination container and lid shown in FIG. 1 and suggesting at section line 1--1 the section of FIG. 1;

FIG. 3 is a fragmentary cross sectional view of the upper portion of the container taken along the section line 3--3 of FIG. 2; and

FIG. 4 is a fragmentary cross sectional view showing the manner in which two containers of this invention nest together.

In FIG. 1 a container C and lid L are shown in their closed relationship to seal the container contents. The container is made of thin sheet plastic material such as polystyrene, and the lid is made of paper. However, the container and lid may be made of other materials.

The one-piece container includes a side wall 10 and a bottom wall 12 joined at the lower corner 14. The side wall 10 adjacent its rim 16 has a combination lid seat and nesting ring 18 that includes a lower shoulder 20, an upper shoulder 22, and an intermediate wall 24 composed of a generally vertical section 26, and upwardly and inwardly inclined section 28 and a second vertical section 30. The upper shoulder 22 comprises the lower part of an upwardly and outwardly inclined wall 32 which merges into the rim 16. While the intermediate wall 24 is shown composed of two vertical sections and an upwardly and inwardly inclined intermediate section, it is to be understood that the intermediate wall 24 may take many other forms. It is only necessary that the shoulder 22 and intermediate wall 24 cooperate to form a bead which will retain the lid L on the container and that the maximum diameter of the shoulder 20 be greater than the minimum diameter of the shoulder 22 to afford adequate nesting. These characteristics are described in greater detail below in connection with FIG. 4.

The maximum diameter of the lid L is appreciably greater than the inner diameter of the shoulder 20 so that the lid will not pass below the shoulder and wedge against the side wall 10 below. The shoulder 20 is intended to form a seat for the lid. It will also be noted that the lid L has a diameter which is substantially equal to the maximum inside diameter of the shoulder 20 so that it engages the inner surface of the vertical wall 26 without excess stress.

When the lid L is to be snapped in place on the shoulder 20 in the lid seat 18, it is first placed on the upper shoulder 22 as suggested in FIG. 1, and thereafter vertical force is applied to snap the lid by the inner edge of the shoulder 22 and the vertical wall 30 to the shoulder 20. In the absence of some specific means for centering the lid L in place, it is evident that when the lid is in the position shown in broken lines in FIG. 1 it may readily shift from one side to the other so as to lose its concentricity with the lid seat 18. If the lid is not centered above the lid seat, pressure applied to the lid may cause the lid to buckle and drive one side of the lid through the lid seat and below the shoulder 20 while the other side of the lid remains on the upper shoulder 22. In accordance with this invention, means are provided to center the lid in place on the upper shoulder 22 so that it is aligned with the lid seat and will not bow and seat improperly when capping pressure is applied.

In accordance with this invention a number of spaced protuberances 34 are formed on the upper shoulder wall 32, which protuberances describe a circle at their inner edges having a diameter which exceeds the diameter of the lid L. When the lid L is centered on the shoulder 22, the outer edge 36 of the lid L is spaced from the inner edge 38 of the protuberances 34. This clearance which may typically be approximately 0.030 inch is sufficient to assure that the lid will fall in place on the shoulder 22 when released by automatic feeding equipment, and it is small enough to assure adequate centering of the lid with respect to the lid seat. The spaced protuberances 34 which extend upwardly from the wall 32 at the rim do not extend to the outer edge 40; and therefore, they do not interfere with the rolling of the rim. Thus, if for example helical screws are used as shown in U.S. Pat. No. 3,355,536 dated Nov. 28, 1967 to roll the rim, the protuberances 34 will not interfere with the rim rolling operation.

While the protuberances serve to center the lid in place so that it may be snapped into the seat 18, they do not interfere with proper nesting of the containers when identical containers are stacked as shown in FIG. 4. In FIG. 4 the lower shoulder 20' of the upper container C' rests on the upper shoulder 22 of the lower container C but within the inner edge 38 of the protuberance 34. Similarly, the protuberance 34' on container C' will not interfere with the nesting of another container on its shoulder 22' when a third container is added to the stack.

In the embodiment shown approximately 20 protuberances 34 are spaced about the upper shoulder 22 of the container. However, there is nothing critical about that number, and a lesser or greater number may be used, and the protuberances may be larger or smaller in a circumferential direction. It is only necessary that there be a sufficient number so as to serve adequately to center the lid L with respect to the lid seat.

From the foregoing it will be appreciated that a paper lid may be dropped onto the shoulder 22 and the protuberances 34 will serve to retain that lid in a centered position with respect to the lid seat 18. No need exists to continuously engage the periphery of the lid L before capping pressure is applied, and the protuberances although retaining the lid in place before capping do not interfere with nesting.

Claims

What is claimed is:

1. A thin wall container comprising

a bottom and a side wall,

a lid seat provided adjacent the top of the side wall, said lid seat being formed as an undercut which terminates at the bottom in a lower shoulder,

a flared rim provided in the side wall immediately above the lid seat and having an upwardly and outwardly directed upper shoulder which terminates at the crown of the rim, and

guide means formed on the upper shoulder spaced about the rim for centering a lid to be snapped by the upper shoulder of the lid seat,

said guide means comprising a plurality of spaced upwardly extending protuberances in the upper shoulder.

2. A thin wall, container as described in claim 1 further characterized by

said protuberances describing a circle about the flared rim, the diameter of said circle described by the inner edges of the protuberances being greater than the outer diameter of the lower shoulder.

3. A thin wall, container as described in claim 2 further characterized by

the outer diameter of the lower shoulder being substantially greater than the inner diameter of the upper shoulder and together defining a nesting facility in the container.

4. In combination with the container of claim 2,

a flat lid adapted to form a closure for the container, said lid having a diameter less than the diameter of the circle described by the inner edges of the protuberances and greater than the inner diameter of the upper shoulder whereby the lid will sit on the upper shoulder within the protuberances until snapped by the upper shoulder to the lid seat.