US3426939A - Preferentially deformable containers - Google Patents

Description

Feb. 11, 1969 w. E. YOUNG 3, 2

- PREFERENTIALLY DEFORMABLE CONTAINERS Filed Dec. '7, 1965 Sheet of 3 INVENTOR. WILLIAM E. YOUNG aka/E72 AGENT Feb. 11, 1969 w. E. YOUNG 3,426,939

PREFERENTIALLY DEFORMABLE CONTAINERS Filed Dec. 7, 1966 heet 2 of s I I I I I I I I l I I I I l l I I I I I I I I I INVENTOR. WILLIAM E. YOUNG AGENT Feb. 11, I969 w. E. YOUNG 3,426,939

I PREFERENTIALLY DEFORMABLE CONTAINERS Filed Dec. '7. 1966 Sheet .7 of 5 12 ER r! 9. Q i

1 Eh I f mi 1 LA 1 1 9; I I A} l L a g JNVENTOR. WILLIAM E. YOUNG AGENT United States Patent Oflice 3,426,939 Patented Feb. 11, 1969 6 Claims ABSTRACT OF THE DISCLOSURE A tray or container of rigid though deformable material which may be plastic such as polyethylene, polypropylene, etc., is formed with at least one preferentially deformable portion similar to a blister. This deformable portion of the tray is in either the side or bottom or both. In the method of packaging a product the deformable portion is moved outwardly to provide a maximum volume for and during filling and is movable inwardly to provide a minimum volume for storage of the product. Inward movement provides a positive evacuation of a determined unfilled space in the tray after which a cover is customarily attached to the tray to retain the contents therein.

Background of the invention Field of the invention.The field of this invention includes containers which are usually in the form of shallow trays. The material of the tray is classified as rigid though the material may be deformed up to its elastic limit and after release return to its formed shape. Automatic packaging in high volume and at high speed requires a package that is simply and completely filled. This container and the easy method of filling for a final full Volume is classified in the art of package making and in particular to methods including those adapted for contents treating. This package is contemplated as most often being heat sealed although a sheet metal tray with a suitably attachable sealing cover would also be within the scope of the field of the invention.

The movement of the trays preferentially deformable portion to one of two extremes is by application of a directed force which after the movement of the portion is completed the force is removed. The movement to the other extreme is by an oppositely moving positive force. The deformable portion is sized and shaped so as to tend to stay in one extreme of movement until acted upon by a force to move the deformable portion to the other extreme. This action is not the action of a collapsible tube nor of a resilient walled container which may be stretched to a larger size and then released to form a preselected smaller size. The field of invention contemplates both the tray or container and the method of filling the container, each tray having a preferentially deformable portion in the nature of or similar to a blister, the deformable portion movable to an outwardly extending position to provide a gross maximum volume and movable inwardly to a net minimum volume.

Problems of the prior art.Automatic packaging of articles and particularly of foods is a highly particular and to a degree a complex art. To properly protect many foods such as those which are semi-cooked, semi-liquid and the like, it is desirable that the amount of air or unoccupied space in the tray or container be very minimal if not completely eliminated. In certain other instances where spoilage is not a factor, the ease of precisely filling a tray or container without spillage during the intermittent motion of an automatic packaging operation is a prime or highly significant factor.

In particular many foods are cooked, placed in clear containers, and then are sealed and shipped for purchase and use by the customer. When these containers have contents such as jams, jellies, and the like, and are incompletely filled, the shipping and handling of the tray or container often splash the contents which by its very composition tend to stick to the sides or top of the tray and the resulting package is unappealing to the prospective purchaser. In many instances a safe packaging for storage of many foods, chemicals, etc., require the unoccupied portions of the sealed container to be filled with a gas such as carbon dioxide or often with some degree of vacuum. The precise filling and sealing of the carbon dioxide or other means of occupying the unfilled portion of the tray is often difficult and on occasion is incomplete. For these reasons a less than completely filled tray or container is often unsatisfactory.

Other factors include the psychological factor in which the purchaser is afraid he is receiving less than he is paying for, which factor is a great concern of the producer if the product is customarily shipped in an incompletely filled tray or container. Where one or both members of the package is transparent or nearly so a void in the package raises a doubt in the purchasers mind as to whether he is receiving full quantity. In fact, all containers which to the prospective consumer appear less than completely filled are always suspect and although the label of the container may have the exact amount of contents and/or weight stated thereon and comply perfectly with all labeling requirements, the opposition of the customer to an apparent shortage of the contents imposes upon the merchandiser an objection to the use of this particular container. In addition, much research and endeavors have been and are being directed towards the providing of a container which is generally of plastic and which is, of course, cheap or inexpensive to manufacture so as to be disposable in the manner of cans and the like. The desired container is often preferably transparent and is scalable with no voids therein.

As far as is known, prior to this invention, no container made of rigid material has been adapted for intermittent feeding to a loading station where is placed in the container a determined volume of less than the total volume of the container and subsequent to the loading operation the container is covered and brought to a full condition. To reduce the unfilled volume of the container after loading and at a later point of the packaging cycle is an intent of this invention.

Prior art and field of search.Commonly known is the high speed filling of collapsible tubes such as toothpaste and the like in which a determined amount is fed into the tube and the open end of the tube is then closed to a determined volume. Also flexible containers having a resilient or stretchable portion of walls are known to provide containers for filling to less than full volume. Such a patent is shown in U.S. Patent 3,104,506 to H. A. Rohdin of Sept. 24, 1963. Rigid trays or containers with preferentially deformable portion or portions as far as is known are not and have not been used for high speed or automatic packaging in which a determined volume of the tray is provided at the time of filling and a determined lesser volume is provided by moving or causing to be moved the preferentially deformable portion.

Summary of the invention:

This invention relates to a tray or container having a preferentially deformable portion providing through its deformable limits a container of two determined volumes.

Particularly this invention relates to a tray or container having a preferentially deformable portion in its bottom or side, said tray as used for the packaging of foodstuffs and the like providing a method for packaging a product in which during filling the tray is deformed to its maximum volume and after filling is deformed to its minimum volume to evacuate a determined unfilled space.

More particularly this invention relates to a tray or continer having a bottom or side with at least a portion thereof preferentially deformable whereby the deformable portion is movable to one limit providing a maximum volume for loading the tray and at or about the time the tray is covered and/or sealed the deformable portion is moved to the other limit to provide a minimum volume substantially equal to the volume of the filling material.

Even more particularly this invention relates to a tray or container of rigid although deformable material and preferably of rigid plastic such as polyethylene, polyvinyl-chloride, and the like, the tray having a preferentially deformable bottom or side portion adapted for a method of filling wherein the deformable portion of the tray is moved outwardly of the interior of the tray during the loading operation whereupon the tray is filled to a predetermined level, whereafter the container is closed with a heat sealable cover or the like and at about the time of or just prior to sealing, the deformable bottom is caused to be moved inwardly to move the contents of the tray to the now substantially if not final total volume of the container.

Even still more particularly this invention relates to a method of filling a tray or container, said container being of a substantially rigid although deformable material, preferably plastic such as polyethylene and having at least one preferentially deformable portion provided in the bottom and/ or a side or sides. The manipulation of the preferentially deformable portion includes the initial step of determining that the deformable portion of the tray is in or is moved to its outer maximum limit of volume for at least the filling sequence in which the tray is provided with a determined quantity of product. After filling and at or prior to the time of covering and sealing of the tray, the deformable portion of the tray is moved to its other or inward limit to provide a positive evacuation of a determined unfilled space of the tray whereupon the sealing of the tray with a cover thereon as by heat sealing finds the tray substantially if not precisely completely filled.

Brief description of the drawings The accompanying drawings, referred to herein and constituting a part hereof, illustrate a preferred embodiment and several alternate equivalents thereof of the invention and together with the description, serve to explain the principles of the invention. In the drawings:

FIG. 1 represents an isometric view partly in section showing one half of a typical tray of rectangular or square construction and having a bottom with a partially conically shaped preferentially deformable portion formed therein;

FIG. 2 represents a plan view of a tray of a round configuration and having a preferentially deformable bottom and with a small flange extending outwardly from the upper edge of the side;

FIG. 3 represents a sectional view of the round container of FIG. 2 and taken on the line 3-3 of FIG. 2;

FIG. 4 represents a plan view of an elliptically shaped container having a bottom with a preferentially deformable portion which is shown as a partially conically shaped portion;

FIG. 5 represents a sectional view of the elliptically shaped container of FIG. 4 and taken on line 55 of FIG. 4;

FIG. 6 represents an isometric view showing one half of a container having sides arranged in a rectangular form and in which the preferentially deformable bottom portion formed therein is ellipsoidally shaped;

FIG. 7 represents a somewhat diagramatic stepby-step pictorial representation of a process in which a preferentially deformable portion of the tray is moved outwardly, filled, sealed, and then by deforming the tray inwardly evacuating the unfilled portion of the tray of this invention;

FIG. 8 represents a fragmentary enlarged view of a lateral edge section of the processing step of FIG. 7 step F;

FIG. 9 represents a somewhat diagrammatic step-bystep pictorial representation repeat of the first five steps of the process of FIG. 7;

FIG. 10 represents a somewhat diagrammatic step-bystep pictorial representaiton of four subsequent steps of an alternate sealing method;

FIG. 11 represents a somewhat diagrammatic step-by- Step pictorial representation of four subsequent steps of yet another alternate sealing method; and

FIG. 12 represents a sectional view of a portion of the resultant product of this invention in which the tray is filled and covered and with the preferentially deformable bottom portion moved to its inward position.

Description of the preferred embodiments Referring now to the drawings in detail in which like numbers designate like members throughout the several figures it is to be noted that in FIG. 1 there is shown a plastic tray or container 10 which includes a side wall 11 extending around the container and having one edge terminating in a top flange 12, which flange is of determined width and is intended to provide a means for attaching of a cover in a manner to be hereinafter described. The bottom 14 of this container, of course, extends inwardly from all of the sides and is usually joined to the side in a continuous small radius or fillet so as to reduce undue strain, this radius is a matter of selection to suit the particular condition of the container as to its pressures and use. The interior portion of this bottom is formed with a preferentially deformable portion which as illustrated consists of a concaved cone 16 having a side sloped wall portion 17 terminating in a top flat circular portion 18. This preferentially deformable portion of the bottom is movable downwardly from the interior of the container as shown in solid outline to the exterior position shown in dashed outline and is moved into this position by the application of a suction cup to portion 18 and the drawing of portion 18 downwardly or by pushing on the preferentially deformable portion in a manner to be hereinafter described.

It is to be noted that the tray or container bodies are formed of a rigid material in that, although deformable, they are not supple. The materials for these trays or containers are preferably polyethylene, polypropylene, P.V.C. (poly-vinylchloride) and similar thermoplastics. The bottom of the tray being the easiest to manipulate is usually but not necessarily selected for the location of the preferentially deformable portion of the tray. When the deformable portion is in the bottom, the sides are made sufficiently rigid to retain the deformable portion in the position to which it is moved. When the deformable portion is in one or more of the side panels the bottom and flange are made sufliciently rigid to retain the deformable portions in the position to which they are moved.

Referring next to FIGS. 2 and 3 there is shown a tray or container 20 of circular construction formed with a circular or arcuate side band wall 22 and an outwardly extending flange 23 attached to the upper edge of the side band wall 22. Extending inwardly from the side wall of this container is a bottom 24 which, in this particular instance, is made with a preferentially deformable portion extending substantially from wall to wall. This deformable portion is conically formed as a truncated cone in which the sloped portion 26 adjoins the outer walls and terminates in a disk top 27. In FIG. 3 it is seen that the bottom member of the tray 20 is also movable outwardly to a position in which the preferentially deformable bottom portion is shown in dashed outline wherein the sloped portion 26 extends inwardly and downwardly to terminate in the disk portion 27.

Referring next to FIGS. 4 and 5 there is shown an elliptically shaped container which includes a side wall 30 having an outwardly extending upper flange 32, said side wall being joined at its lower edge by a bottom member 34 having a preferentially deformable portion formed therein and positioned intermediate the side wall 30. The deformable portion, in the present instance, is a circular portion in the form of a truncated cone having a sloped wall 36 terminating in a disk portion 37. As illustrated, the inward extent of the preferentially deformable portion of this bottom is shown in dashed outline in which the sloped portion 36 extends inwardly and upwardly terminating with a disk portion 37.

Referring next to FIG. 6 there is shown an alternate embodiment of a rectangular tray or container 40 having side walls 42 terminating on their upper edges with an outwardly formed flange 44 and having a bottom 46 extending from wall to wall. This bottom has a preferentially deformable portion formed intermediate the side walls and formed as a truncated ellipsoid in which the sloped portion 48 begins near the side walls and less near the end walls and extends downwardly and inwardly and terminates in an elliptical disk portion 49. Shown in dashed outline is the bottom portion after it has been preferentially deformed and moved to its inner position and with the sloped walls 48 extending upwardly and inwardly and terminating with the disk portion 49.

Referring next to FIG. 7 there is shown a diagrammatic representation of a series of steps used in the filling and sealing of a tray such as above described in conjunction with FIGS. 1 through 6. The preferred method includes a belt 50 having equally spaced and like sized pockets provided therein, the belt being advanced in an intermittent manner. However, it is to be noted that cooperating members of a continuously moving belt can be arranged to reciprocate so that they can engage successive trays to provide the desired motions for the filling and closing of the tray. Removably mounted in each pocket in the belt 50 and by conventional means not shown is a tray such as shown in FIG. 1. As molded, the tray 10 has its preferentially deformable portion 16 in the upward position so that any inherent strains developed in the process of molding cause the preferentially deformable bottom portion to tend to remain in the upward position seen in position A. At position B the belt has transported the container 10 to a location in which the deformable portion is in the way of a vacuum sucking device or a vacuum application device 52 which is now in its upward position and in engagement with the disk portion 18 of the bottom. With the application of vacuum on device 52 and in vacuum sealing position with the disk shaped portion 18, the vacuum device 52 is next moved downwardly carrying the deformable bottom portion to a downward or outer condition to provide a gross volume of the tray.

In position C of FIG. 7 the container is shown with its preferentially deformable portion moved to its maximum content condition whereupon the vacuum in device 52 is cut off disengaging the device from the tray bottom whereupon the device is moved further downwardly, permitting the belt to be advanced or moved. Although the stations B and C are shown with a preferred vacuum device 52 it is to be noted that the preferentially deformable portion may be moved to the outward position by means of a pusher moved downwardly from above the tray. This pushing method of moving the deformable portion outwardly is avoided where the inner surfaces of the container are sterilized for the storage of foodstuffs and the like. When the tray is to be used for a product requiring no sterilization the pusher method is usable to avoid the expense involved in the use of vacuum.

After the step of moving the preferentially deformable portion to its bottom or gross volume condition, the tray 10 is advanced to a position for filling as seen in station D. The tray is brought under a filling spout 54 or the spout 54 is brought in way of the open top of the container and the product 55 in a determined amount is dispensed into the tray filling it to a selected height. This height is a determined distance below the upper edge of the flange 12 of the container. After filling the tray is advanced further down the line as indicated in station E and passes into a sealing chamber as indicated at station F.

F, G and H represent the same station in that in the preferred embodiment shown the belt 50 is not advanced in these operations, however, the cover and sealing operation is shown in three stop motion operating sequences. The sequence indicated at station F of FIG. 7 illustrates an early step in the operation in which tray 10 is surrounded by a bottom member 56 which supports the side wall. Member 56 is at its upwardly moved position wherein it engages and supports belt 50 and the flange 12 of the tray. As a part of and leading from the chamber portion of member 56 is a conduit 58 which is operatively connected to a vacuum, gas and/ or like source not shown but which is used in the particular over-all processing of the product at the time of covering and/or sealing. In the bottom of member 56 there is provided a pusher 60 to be hereinafter described as to its use.

Above the belt 50 there is apparatus adapted to feed a top sealing member or cover 62 which is usually a continuous strip of sheet material having a heat sealable plastic lower portion and is positioned on the lip 12 of the tray. Immediately above the belt and aligned with bottom member 56 is an upper member 64 movable downwardly and providing thereby a clamping action of the strip '62 against the flange 12. In member 64 there is a conduit 66 which is operatively connected to a vacuum, gas and/or like source to provide a desired condition to the filled tray at the time of covering and/ or sealing. Movable downwardly inside the upper member 64 is a heat sealing platen 68 having downwardly extending outer edges sized and positioned so as to engage the plastic cover 62 and by means of heat and pressure applied at its edge portion '69 form a heat seal between said cover and the plastic lip 12 of the plastic container. In the stage hereby shown it is anticipated that vacuum, gas or the like is applied to both chambers 56 and 64 so that the closed chamber formed by the upper member 64 and the lower member 56 is under diminished pressure, gas or the like as is the unfilled portion of the tray above the product 55 deposited at stage D.

Referring next to FIG. 8 it is noted that at the time of application through conduit 66 and to the inside of upper member 64 of vacuum, gas, and/or the like the interior of the filled tray is in communication with the top chamber portion. The cover '62 is not brought into contact for sealing to the lip of the tray until the chamber and the unfilled tray portion has been conditioned or treated in accordance to the product to be packaged. The path of the arrows is representative of the flow across the product 55 and from the interior of the package.

Referring next to stage G (FIG. 7) it is to be noted that the sealing platen 68 has been moved into engagement with the cover and with the covered tray having a vacuum, gas or the like within its unfilled portion. The tray is now heat sealed substantially or completely around the cover and the lip 12. Referring next to station H it is seen that the heat seal member 68 has been moved upwardly from the cover while the lower chamber still engages the tray and the belt. Prior to movement of heat seal member 68 upwardly the preferentially deformable bottom portion has been moved upwardly to its inner position by a pusher -60 to move the product 55 Within the tray upwardly to fill the displaced unfilled portion of the covered tray and bring the product in the way of the cover of the container. The pusher 60 moves the preferentially deformable bottom 16 upwardly at or before the complete final seal of the cover 62 to the lip 12. This is merely a matter of timing and selection as determined by the product and its method of storage before consumption. This is hereinafter more fully described in the use and operation of the tray and method.

Referring next to FIG. 9 the steps A, B, C, D and E are represented as and are the same steps as the steps A, B, C, D and E of FIG. 7 described above. The filled tray with the preferentially deformed bottom in the outer position may then be presented to an alternate sealing sequence shown in diagrammatic outline in FIG. 10 and in stations F, G, H and I.

In station 10-F the filled tray has a cover 162 which may be or is similar to the continuous strip material 62 of FIG. 7. The cover is then heat sealed on all but a portion of the common meeting line of the flange of the tray and the cover. The heat sealing platen portion at station G effecting the initial seal is indicated as 168. Although represented as a three side initial seal, said initial seal can be any portion less than a complete seal just so the unsealed portion permits ready expulsion of the gas or air occupying the unfilled space in the container. The cover is retained on the tray and the tray is retained in the conveyor by the sealing platen which is still in the lower position as the preferentially deformable bottom is moved upwardly as in station H. This upward movement of the deformable portion expells the gas or air in the unfilled portion of the container and at station I the remaining cover portion is sealed to the flange with the downward movement of a sealing bar 170. After the sealing the container is moved to a position (not shown) for the removal of the finished package from the conveyor 50. Sequences F, G, H, and I are contemplated to be diagrammatic representations of actions performed in one location in space, however, they may be sequentially made in one or more separate positions and particularly with the final seal in a subsequent position to the initial seal.

Referring next to FIG. 11, from steps A, B, C, D and E of FIG. 9 the filled tray is provided with a cover 262 which in position 11F is brought in the way of the flange of the tray and is positioned adjacent a sealing platen 268. Cover 262 is preferably similar to cover 62 above and in position 11G is heat sealed to the flange of the tray. After heat sealing the tray is moved to a further position represented by 11H wherein the preferentially deformable bottom is moved upwardly an amount sufficient to cause the bottom to be urged inwardly. The cover 262 as a result of the movement of the deformable bottom is stretched or bowed outwardly and remains so until the gas or steam occupying the unfilled portion of the package is absorbed in the product, condenses, or is passed through a permeable cover or tray until the resulting package has the form shown in station 11I. Such adsorption, condensation or permeation may be allowed to occur in a later storage of the product rather than when the tray is in belt 50.

Referring finally to FIG. 12 the final packaged product as seen in a partial and sectional isometric view shows the product or contents 55 within covered tray 10 and with the preferentially deformable bottom now in its inward position. The movement of the deformable bottom portion has displaced the contents upwardly to occupy the displaced void so that the product is adjacent or in contact with the cover 62 now heat sealed to lip 12 during the sequence of sealing described above.

Use and operation The unique package and method of forming and filling as exemplified in this invention is best seen in the sequences of FIGS. 7, 9, 10 and 11 above-described. Of particular note in the packaging process above-described is that the trays, when practical, have their preferentially deformed bottom portions molded in the upward position. The container as it is intermittently advanced by the conveying belt 50 has its bottom moved downwardly at one stage of advancement. The bottom, now outwardly deformed is moved to the filling sequence at which stage the volume of the container is at its maximum. After the product 55 is poured into the container in a determined volume or quantity the preferentially deformable bottom portion is moved upwardly to the inner position whereupon the void or the unoccupied portion or portion thereof of the tray is exactly displaced by the precise change in volume caused by the preferentially completed deformation.

The three methods of filling and sealing shown in FIGS. 7, 9, 10 and 11 contemplate that the container will be presented to the sealing step with the preferentially deformable portion in the outward condition and with a volume of product in the tray substantially equal to the tray volume with the preferentially deformable tray portion in an inward position. In addition to the vacuum or a partial vacuum in the chamber of FIG. 7-F, gas or other desired media could be used. If the gas were carbon dioxide or steam the gas would be administered to the void of the tray at approximately atmospheric pressure through spout at positions 10-F and 11F prior to bringing the cover to the tray for the subsequent sealing procedure. Where carbon dioxide is used as in FIG. 11 the cover 262 as well as the tray may be permeable so the packaged tray eventually assumes the configuration of FIG. ll-I. Carbon dioxide may also dissolve into the product to eliminate the carbon dioxide as the gaseous void.

The above method of filling is also applicable in those cases where a gas flush is applied to the filled tray prior to the covering and sealing so that a small amount of carbon dioxide is left in the open tray before the application of the heat seal to the tray and cover and the inward movement of the preferentially deformable bottom portion. Live steam, as a condensable gas to displace the air, may also be applied to the unsealed tray as a flush to fill the void. After sealing, the steam condenses or is caused to condense to eliminate it as the gaseous media of the filled tray and with the condensate of the steam laying on or mixing with the product. The condensation of the steam provides a reduced pressure within the sealed tray which under certain conditions is sufficient to induce and/or complete the inward motion of the preferentially deformable portion of the tray. It is also to be noted that in certain operations a vacuum may be applied to the chamber within the closed member 56-64 in order to remove the air after which a small cut back may be made with a gas such as carbon dioxide which is dependent upon the operation and the material to be stored.

The methods of filling the trays above-described and contemplated requires only that the tray have a preferentially deformed portion in either the bottom and/or sides and be in an outwardly expanded or extended condition during the filling and at or after closing and sealing the preferentially deformable portion be moved or have been moved to an inner condition. The preferential deformation provides on the inward movement a minimum closed space in the container which space is occupied by a vacuum, gas, steam or the like. The conveyor 50, as above-described, may also be moved in a continuous manner with many of the operations being performed with reciprocable apparatus adapted to cooperatively move with the tray as it is advanced and in other steps of operation, as for example filling, providing the step as the tray is passed in the way of the apparatus.

It is to be noted that in the sequence of FIG. 7, the pusher 60 may be eliminated if the sequence, after sealing, permits air to enter conduit 58 while vacuum is maintained above the cover. The atmospheric pressure in this instance would replace the pusher and pneumatically move the preferentially deformable portion inwardly to FIG. 7-H.

It is also noted that cover 62, 162 and 262 although shown and described as strip material may, of course, be individual covers which are blanked, molded or otherwise shaped to the desired size. The trimming of these or strip covers from the package is a matter of selective application and is considered conventional.

In the packaging trade the trays above-described are usually of plastic which when formed are termed semirigid. In the thaicknesses usually provided for trays the sheet plastic is rather easily bent but not fractured. The material after bending readily returns to its as-forrned condition. The contemplated plastics for the trays such as polypropylene may not have tensile strength but rather a tensile yield at which point it reduces in area. The preferentially deformable portion of the tray as it is moved from one limit to the other limit does not exceed such a yield.

The trays and covers above-described are discussed as heat sealable plastic, however, a tray of sheet metal or other rigid material not normally considered heat sealable as to this application may be formed and used. The cover for the container may be attached as by clamping, cementing or providing a sealing shoulder in the manner of paint cans and the like. It is only intended that the concept of the preferentially deformable portion be considered in the advancement of the art of packaging.

The terms up, down, in and out and similar terms are applicable to the tray and process as described in conunction with the accompanying drawings and it is to be noted that such terms are merely for the purpose of description and do not necessarily apply to a position in which the tray or method may be constructed or used.

The invention in its broader aspects is not limited to the specific embodiments shown and described but departures may be made therefrom within the scope of the accompanying claims, without departing from the principles of the invention and without sacrificing its chief advantages.

What is claimed is:

1. An open top tray of unitary construction and having substantially rigid sidewalls and bottom, said tray having means for attaching a cover to the open top, said bottom comprising a planar collar portion having its outer periphery connected to the sidewalls; a preferentially deformable frusto-conical portion having its larger end integral with the inner periphery of said collar portion and a closure disc integrally connected to the smaller end of the frusto-conical portion and lying in a plane generally parallel to the plane of the collar, said closure disc through the fiexure of said frusto-conical portion being adapted to be moved to one of two positions and in each position to be generally parallel to the collar portion, said preferentially deformable frusto-conical portion after it is moved to each of the positions of movement is disposed to remain in said position and in the absence of a cover on the tray, the outer limit position providing a gross volume to the tray whereat the tray may be filled with a determined volume of product and after filling, the preferentially deformable frusto-conical portion is movable to an inner limit position providing a positive evacuation of a determined portion of the tray.

2. A tray as in claim 1 in which the outer periphery of the collar is rectangular and the sidewalls are disposed in a rectangular manner at the outer periphery of said collar.

3. A tray as in claim 1 in which the outer periphery of the collar is circular and the sidewall is disposed in an arcuate manner at the outer periphery of said collar.

4. A tray as in claim 1 in which the outer periphery of the collar is elliptical and the sidewall is disposed in an elliptical manner at the outer periphery of said collar.

5. A tray as in claim 1 in which the outer periphery of the collar is polygonal and the sidewalls are disposed in a polygonal arrangement about the outer periphery of said collar and the preferentially deformable portion formed in the bottom is in the shape of a truncated cone having a normal base of elliptical shape.

6. A container as in claim 1 in which the unitary construction is a molded tray of a thermoplastic material such as polyethylene, polypropylene and the like.

References Cited UNITED STATES PATENTS 1,913,652 6/1933 Alexander 220-66 2,012,213 8/1935 Young 220-66 2,971,671 2/1961 Shakman 220-66 3,103,089 9/1963 Allen 53-30 X 3,104,506 9/1963 Rohdin 53-22 3,325,031 6/1967 Singier 150-.5 X 3,342,009 9/1967 Anderson 53-22 FOREIGN PATENTS 532,675 11/ 1954 Belgium.

JOSEPH R. LECLAIR, Primary Examiner.

JAMES R. GARRETT, Assistant Examiner.

U.S. Cl. X.R. 220-

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