US 3349950 A
Description (OCR text may contain errors)
Oct. 31, 1967 H. J. WANDERER 3,349,950
CONTAINER WITH SEGMENTED LID SEAT Filed Oct. 24, 1965 INVENTOR. Herbert J Wanderer His Arr' s United States Patent l 3 349 950 CONTAINER WITH SEGMENTED LID SEAT Herbert J. Wanderer, Elmhurst, Ill., assiguor to Illinois Tool Works Inc., Chicago, 11]., a corporation of Delaware Filed Oct. 24, 1965, Ser. No. 504,336 Claims. (Cl. 220-60) ABSTRACT OF THE DISCLOSURE A thin wall plastic container having a segmented or interrupted lid seat construction which provides improved lid retention characteristics while accommodating lids of varying diametrical measurement.
Container lid seats in the form of an internal groove located adjacent the open mouth of a container for receiving a complementary portion of a lid member are well known in the art. Although various modifications have been made to the conventional lid seat form including pressure equalization features permitting the venting or entry of air relative to the container body, it has been the primary function of the container lid seat to support and retain a lid member in assembled position relative to a complementary container body.
It is common knowledge that the lid retention capabilities of lid seats will be increased when the undercut formation of the internal groove is deepened; however, there are certain factors that limit the relative depth of the undercut formation. If the undercut formation is too deep, removal of the container from a complementary mold member is not possible without some damage. Where the containers are made from thermoplastic material as contemplated by the present invention, the inherent flexibility of the material will enable these containers to contract circumferentially, and thereby reduce the possibility of attendant damage upon removing containers from a mold member. To remain competitive with their paper counterpart, plastic containers have been made relatively thin-walled in nature, and this aspect, as will be apparent, limits the degree to which circumferential contraction is possible without tearing or breaking open the container body in the vicinity of the container lid seat. The present invention strikes a balance in the above mentioned and other factors in providing a new and improved container lid seat for a thin-wall thermoplastic container of seamless construction.
One object of the present invention is to provide a container lid seat in a thermoplastic container having a relatively deep undercut formation without interferring with the removal or ejection of the container from a complementary mold member.
Another object of the present invention is the provision of a novel container lid seat in a thermoplastic container requiring a minimum amount of force to remove it from its forming mold.
Still another object of the present invention is the provision of a novel container lid seat which is relatively flexible in a diametrical sense to facilitate removal from a complementary mold member and accommodate lid members of varying diametrical measurement, while being strong enough to retain a lid member in assembled relationship to a complementary container body.
Yet another object of the present invention is the provision of a novel container lid seat in a thin-wall thermoplastic container which permits the assembly and retention of lid members of either the inserted or overcap variety.
3,349,950 Patented Oct. 31, 1967 Other and further objects and advantages of the present invention will become apparent in the following description when taken in connection with the accompanying drawing:
FIG. 1 is a perspective view of a container package including a lid member and a thermoplastic container body having a container lid seat incorporating the principles of the present invention;
FIG. 2 is an enlarged, fragmentaly side elevational view partially in section, of a thermoplastic container body in the vicinity of its container lid seat;
FIG. 3 is a fragmentary vertical sectional view of a container mold member used in forming the container lid seat of the present invention on a thermoplastic container body;
FIG. 4 is an enlarged fragmentary vertical sectional view of the mold member shown in FIG. 3 illustrating the forming and ejection of a thermoplastic container body incorporating the container lid seat features of the present invention; and
FIG. 5 is a fragmentary enlarged top plan view of the thermoplastic container body shown in FIG. 1, and illustrating the degree to which the container lid seat flexes as it is removed from a complementary mold member.
Referring now more specifically to the drawing, and first to FIG. 1, there is shown a container package 10 comprising a container body 12 and a lid member 14 having a side finger tab 16 facilitating the removal of the lid member or disc 14 from the container body. The internally fitting lid member or disc 14 is preferably made from paperboard or the like while the container body, in its preferred form, is integrally molded as a seamless thermoplastic container from materials such as polystyrene, polyethylene, polyvinyl chloride and the like. Lid means of various constructions can be used with the container body 12 ranging from the flat lid member or cover disc 14 to container lids having snap-in features such as shown in US. Patent No. 3,061,139 and overcap closures,
an example of which is shown in US. Patent No. 3,178,051.
The container body 12 illustrated in FIG. 1 of the drawing is generally of the type shown in Design Patent 199,336 having a bottom wall 16, and an upwardly and outwardly diverging sidewall 18, including a plurality of axially spaced, circumferentially extending strengthening ribs 20 which afford lateral strength to the container, and serve to some degree, in preventing slippage of the container from the hand of a user. The container sidewall 18 terminates at its upper end in a rolled over rim which also increases the lateral strength of the container in the vicinity of its open mouth as well as provides a lip suitable for drinking purposes. Adjacent the bottom wall 16 of the container, a stacking area 24 is provided for stacking a plurality of similarly configured containers in non-jamming relationship. Stacking area 24 includes a stacking ring 26 having upper internal and lower external shoulders, and a series of peripherally spaced wedges or cam surfaces 28 which extend between the lower external shoulder of the stacking ring 26 and the sidewall 18 of the container. The function of the wedges 28 is to cause each container in a stack to be forced slightly inwardly in the vicinity of the wedges while containers externally thereof are forced outwardly where engaged by the wedges. The result is the creation of a resilient stack of containers which prevents container jamming and insures ready separation of adjacent containers from each other. For a detailed discussion of the function and operation of a resilient stacking means in a thin-walled thermoplastic container, reference is made to US. Patent No. 3,091,360.
Each container 12 is preferably formed in one piece from heated thermoplastic material by conventional thermoforming techniques, an example of which is disclosed by US. Patent No. 2,891,280. A brief discussion of the thermoforming principles disclosed in US. Patent No. 2,890,280 will facilitate an understanding of the present invention. Containers are formed from a heated web of thermoplastic material which is intermittently fed or moved by suitable advancing mechanisms from an extruding mechanism to a forming station having one or more molds and complementary plungers or die assemblies. After the web is clamped in place at the forming station, the plungers and molds are relatively advanced toward each other so that the plungers draw the plastic material into the mold to partially form the container. Then, the partially formed containers are sealed from the remainder of the web, and a differential fluid pressure is established to expand the partially formed container against the walls of the mold cavity to complete the formation of the container or containers. Removal of the containers from the mold cavities is then effected, and this can be accompanied by severance of the containers from the web prior to ejection if desired.
When forming containers according to this technique, consideration must be given to the depth of undercut formation embossed in the container body to preventinterference and consequent damage of the container body during the ejection or removal stage. Although thermoplastic containers made from materials such as polystyrene, polyethylene, polyvinyl chloride and the like will provide inherent flexibility during container withdrawal making it possible to strip containers with certain types of embossment from mold cavities, there is of course, a limit to the amount of flexibility that is possible, particularly in view of the thin-wall nature required of such containers to make them competitive. In the usual case, thermoplastic containers made 'by the thermoforming technique have a wall thickness in the neighborhood of .002.034 inch necessitating careful manipulation of the containers during the forming stage.
On the other hand, it is recognized that the relative depth of certain embossments determines the extent to which they are effective in carrying out their intended function. A particular example is in the area of container lid seats with which the present invention is concerned. It is recognized that the deeper the undercut formation in the container lid seat, the better it will retain a complementary interfitting portion of a lid member. Yet, restrictions are imposed by the very nature of the technique used to form thermoplastic containers as has been discussed above. In striking a balance on the above enumerated aspects, the present invention provides a segmented or interrupted container lid seat generally designated 30 in FIG. 1 of the drawing. As best seen in FIG. 2, the segmented lid seat 30 is located immediately below the rolled or curled rim 22 of the container body, and includes a lid abutment surface 32, a plurality of circumferentially spaced, inwardly extending protuberances 34 which are separated from one another by a generally vertically extending connecting wall section 36. The lid abutment surface 32 extends in a peripheral fashion around the container body and is radially outwardly directed from the uppermost extremity of the container sidewall 18. The lid abutment surface 32, therefore, provides a horizontally extending supporting surface or shelf which will support an interfitting lid member on the internal wall surface thereof, and will provide an external shoulder or abutment surface for cooperation with a locking flange or the like for an overcap closure construction.
Each internally extending protuberance 34 is in the form of a pair of converging, oppositely disposed upper and lower wall portions 38, 40 which presents a V-shaped configuration terminating in a relatively discrete apex 42. The apical portion 42 for each protuberance lies in a common plane to serve as the innermost portion of the undercut formation in the container lid seat 30. It is to be specifically noted that each protuberance 34 is axially spaced upwardly from the plane containing the lid abutment surface 32 and axially spaced downwardly from the rolled over rim 22 to obtain maximum flexibility of the protuberances 34 without any interference from the lid abutment surface 32 or rolled over rim 22 which would naturally tend to prevent radial contraction or expansion of all container areas lying in the planes containing such features.
The connecting wall sections 36 are generally vertically directed with the outer extremities of each section curving radially inwardly and merging with the extremities or ends of adjacent inwardly extending protuberances 34. The disposition of and the manner in which each connecting wall section 36 merges with adjacent protuberances 34 affords a substantial amount of lateral strength to the segmented lid seat 30 without impeding radial expansion or contraction of the same.
In forming containers 12 with a segmented lid seat 30 in accordance with the thermoforming technique, a mold cavity 50 as depicted in FIGS. 3-4 of the drawing is employed. Although only a part of the mold cavity 50 is shown in FIGS. 3-4 of the drawing, it will be understood that it includes various container mold portions for forming the stacking area 24, the reinforcing or strengthening ribs 20 as well as the segmented container lid seat 30. To highlight the features which are characteristic of the present invention, FIGS. 34 of the drawing generally illustrate only that portion of the mold cavity 50 wherein the segmented lid seat 30 is formed. The mold cavity 50 is annular in form, and may be either one piece or a plurality of interfitting mold components which form various areas of the container 12. As seen in FIGS. 3-4 of the drawing,
the mold cavity 50 includes an upper mold body portion 52 having the necessary formations to mold the segmented lid seat, and a mold insert 54 for forming the upper two reinforcing or strengthening ribs 20 in the container. More specifically, it will be seen that the upper mold body portion 52 is configured to provide an internal wall surface 56 which forms the upwardly and outwardly diverging sidewall portion immediately below the segmented lid seat 30, a horizontal mold surface 58 which forms the lid abutment surface 32, a mold surface 60 including a plurality of circumferentially spaced, inwardly extending V-shaped mold projections 62 corresponding in number, size and location to the inwardly extending abutments 34 for forming the same, and a rounded over upper end 64 which forms the initial shape of the lip at the open mouth of the container prior to folding or curling thereof as best seen in FIG. 4.
Once the container is formed, for example, in accordance with the above mentioned thermoforming technique, the withdrawal or ejection thereof from the mold cavity is easily effected. There will be no interference from the inwardly extending mold projections 62 in the container lid seat area since the segmented construction of the protuberances 34 will enable the container to radially contract taking into account the inherent flexibility of the material from which the container is made. As a result, the acute angle between the lower wall portion 40 of each abutment 34 and the lid abutment surface 32 can be made relatively small to increase the depth of the undercut formation beneath each apical portion 42, without interfering with the ejection or removal of the container. This is readily depicted by the phantom lines in FIGS. 4-5 of the drawing wherein it will be noted that the protuberances 34 and the connecting wall sections 36 will be slightly deformed radially inwardly as the container 12 is ejected from the mold cavity 50 to provide a minimum diameter measurement enabling the passage of the segmented lid seat beyond the mold projections 62 without any damage to the lid seat area of the container.
The segmented lid seat construction also provides radial expansion thereof in varying amounts depending upon the diametrical measurement of the cooperating lid portion. Variations in lid diameters, out-of-round lid formations and the like have been found to occur in many lid or cover disc products and the present invention accommodates such lids, and other lids of varying diametrical measurements to a predetermined degree.
It will now be apparent that the present invention contemplates a new and improved lid seat in a thin-wall thermoplastic container article wherein a relatively deep undercut formation may be provided without in any way hindering the removal of the container product from its mold member after forming thereof. The segmented container lid seat will not only effectively retain an associated lid or disc member, but will accommodate larger variations in lid diameters than is possible by present approaches.
It is to be understood that the specific example of the invention herein shown and described is for illustrative purposes only. Various changes in structure will no doubt occur to those skilled in the art, and will be understood as forming a part of this invention insofar as they fall within the spirit and scope of the appended claims.
What is claimed is:
1. A thin wall plastic container of integral one-piece construction having a bottom wall and a side wall diverging upwardly and outwardly therefrom to a rim portion adjacent the open upper end thereof, and a segmented lid seat formed in said cup side wall immediately below said rim portion including a circumferentially extending lid abutment surface radially outwardly directed from said side wall, and an annular series of circumferentially spaced, inwardly extending protuberances integrally joined to said lid abutment surface and extending upwardly therefrom, each inwardly extending protuberance having a lid engaging surface disposed at an acute angle to said lid abutment surface, adjacent internally extending protuberances being separated from each other by a substantially axially extending connecting wall section which is uninterrupted throughout the axial height of said protuberances and which is provided with generally radially inwardly curving extremities merging with adjacent internally extending protuberances whereby to present a relatively strong, yet flexible lid seat.
2. The container as set forth in claim 1 wherein each internally extending protuberance is in the form of a pair of converging, oppositely disposed wall portions presenting a V-shaped configuration which terminates in a relatively discrete apex internally of said cup.
3. The container as set forth in claim 1 wherein the juncture between the annular series of circumferentially spaced, inwardly extending protuberances and said lid abutment surface is radially inwardly ofiset from the rim portion of said cup.
4. The container as set forth in claim 1 wherein the innermost projection of each inwardly extending protuberance is radially outwardly offset from the juncture of said lid abutment surface of said cup sidewall.
5. The container as set forth in claim 1 wherein said annular series of inwardly extending protuberances is axially spaced from said rim portion and said lid abutment surface to afford maximum flexibility thereto.
References Cited UNITED STATES PATENTS 3,262,602 7/ 1966 McConnell et al 220 DONALD F. NORTON, Primary Examiner. THERON E. CONDON, Examiner.
G. T. HALL, Assistant Examiner.