2. The Relevant Technology Articles having a starch-bound matrix, whether foamed or nonfoamed, are gaining increasing attention in the marketplace as a useful alternative to substantially non- renewable or long-term renewable resources such as polystyrene or paper. Such starch- based materials can be typically formed by molding, extruding, rolling, and other well- known shaping processes. Die press molding is a particularly useful method for manufacturing 3-dimensional articles from starch-based materials.

Die press molding generally involves placing an appropriate composition between a pair of molds, usually paired male and female molds, and then closing the molds in order form a die cavity within the mold pair corresponding to the shape of the desired molded article of manufacture. In the case of aqueous starch-based compositions, it will usually be necessary to provide vent holes or some other vent means for releasing pent up water vapor that forms as a result of heating the aqueous starch-based compositions.

The formation of internal water vapor is beneficial in that it causes the mold material to expand and fill the mold cavity. Further heating causes the expanded mold material to become dry and substantially solidified.

In general, it will typically be necessary to employ an excess of mold material in order to ensure complete formation of the molded article. Under-filling of the molds may result in discontinuities or other defects within the molded articles. Inadequate pressure buildup due to under-filling may also result in the collapse of the cellular structural matrix before being solidified into the desired 3-dimensional shape. Depending on the location of the vent holes, the uniformity or lack thereof of heat applied by the molds, as well as the rate of expansion and the flow properties of the mold material, different sections of the mold cavity may preferentially fill before other sections, thus necessitating

an initial excess of mold material within the mold cavity.

Whereas the use of excess mold material increases the likelihood that the molded articles will be properly formed, such an excess of mold material will either have to be expelled from the molds through the vent holes or other venting means or else heavier, more dense articles will result. In order to yield articles having substantially uniform weight and density it will usually be desirable for the excess mold material to be allowed to escape from the molds.

Upon being expelled from the molds, the excess mold material will typically harden and remain attached to the molded articles, thereby forming unwanted irregularities which are sometimes referred to in the art as"flashing". Flashing can be quite conspicuous and substantial and will generally need to be removed in order to prevent clogging of the downstream handling equipment and in order to yield an aesthetically pleasing article. The flashing must usually be removed before further processing can take place, which is just after demolding. However, newly molded articles are usually in their most fragile and brittle condition in the moments just after demolding, since strength and flexibility are usually imparted to the starch-bound cellular matrix by means of coating and/or absorption of moisture.

One method that has been used involves the use of a scraper to mechanically remove the flashing from the molded articles. The scraper generally works by being dragged across the tops of the molds after separation of the mold halves and just prior to demolding of the articles in order break off and remove the flashing. One downside of using a scraper is that it works by crudely breaking off the attachments that connect the flashing to the article wall, which can leave divots, protrusions, cracks and other irregularities. Another problem is that more strongly attached flashing can actually resist breakage at the desired point, which may result in fracture of the article sidewall instead, thus resulting in an article that must be removed from further processing and discarded.

In view of the foregoing, what is needed are apparatus and systems for removing flashing and other irregularities from molded starch-bound articles which did not result in the substantial formation of divots or other depressions which could be mechanically and/or aesthetically undesirable.

In addition, it would be an advancement in the art to provide apparatus and systems for removing flashing and other irregularities from molded starch-bound articles which did not leave substantial quantities of burrs or other raised portions which could be mechanically and/or aesthetically undesirable.

It would be a further advancement in the art to provide apparatus and systems for

removing flashing and other irregularities from molded starch-bound articles which did not cause substantial fracture or other types of mechanical failure of the molded articles upon removing the flashing or other irregularities.

It would yet be an advancement in the art if such apparatus and systems for removing flashing and other irregularities from molded starch-bound articles provided for the recycling of such materials back into the molding compositions used to manufacture additional articles of manufacture.

Such apparatus and systems for more efficaciously removing flashing and other irregularities from newly molded articles of manufacture, particularly articles having a starch-bound cellular matrix, are disclosed and claimed herein.

SUMMARY The present invention relates to apparatus and systems for removing irregularities from molded starch-bound containers and other articles. Such apparatus and systems are designed to remove virtually all such irregularities while substantially preventing or eliminating divots or other depressions and burrs or other raised irregularities in the finished articles. Such apparatus and systems also result in far less breakage of the molded articles compared to previous methods for removing flashing, such as scraper blades. The result is a higher percentage of finished articles having virtually no irregularities while keeping inadvertent damage to a minimum.

The processes for molding foamed starch-bound articles from aqueous starch- based compositions typically yield flashing having one or more globular structures which remain attached to an upper edge of the molded articles by one or more narrow stems or strands. The attachment strands typically have a diameter that is similar, or at least proportional, to the diameter of mold vent holes used to vent water vapor and excess mold material from the heated molds. The mold vent holes have a diameter typically in the order of 0.040-0.060". Thus, the attachment strands will typically be quite narrow and, thus, fragile, which makes them easy to snap off by bending, which is the concept typically employed by scraper blades. However, such strands or stems will typically break off at their weakest point, which is not always where the strands emerge from the article wall, thus resulting in some residual portion of the strand. In the case of particularly well-formed strands of atypically high strength, the strands my not break off at all but detach deeper down in the article wall, thereby resulting in the formation of an unwanted divot or cavity.

On the other hand, the globular structures may vary greatly in size and but will generally have a total combined size that is proportional to the amount of overfill in the

mold apparatus. Sometimes the globular structures will form discrete balls at the ends of the attachment stems or strands. Other times the globules may themselves merge together to form interconnected globular structures of substantially greater size attached to the molded article by a plurality of attachment strands. In most cases, the globular structures will comprise the vast majority of the flashing mass while the attachment strands will only comprise a minor portion.

In view of the tendency for the majority of the flashing mass to comprise relatively large globules attached to the molded articles by one or more narrow diameter strands, a preferred system for removing flashing involves a two-stage removal process: (1) a first rough flashing removal step for removing the globules and a substantial portion of the attachment strands and (2) a second fine flashing removal step for carefully removing the remaining portions of the attachment strands. Nevertheless, it is within the scope of the invention to employ only one of the foregoing removal steps or to employ other finishing processes in addition to one or both of the foregoing steps.

In a preferred embodiment, the rough flashing removal step is preferably carried out by a mechanical cutting process that results in cutting, rather than mere breakage, of the attachment stems. A preferred cutting apparatus for carrying out the first step is configured so as to have a cutting motion transverse to the attachment strands in order for the cutting process to actually cut or slice, rather than bend or break, the flashing.

Preferably, the cutter will comprise a saw blade or sharp knife blade that is oriented substantially perpendicular to the attachment strand axes and which moves in a transverse direction in order to slice off the strand at the point where the strand meets the blade or knife edge. The blade or knife may move from side-to-side, around in a circular motion, or in any other appropriate manner in order to facilitate cutting or slicing of the attachment strands. The blade or knife is preferably located a safe distance from the article proper so as to avoid unwanted cutting or other damage to the article wall itself.

The foregoing apparatus comprise a preferred rough finishing subsystem.

After the rough finishing station cuts off the attachment strands at a desired location or height above the article wall, a residual nub or"whisker"attached to the article is often left behind depending on the margin of safety represented by the distance between the cutting blade and article wall. The residual nub height represents a margin of safety which prevents the rough finishing blade or knife from cutting or otherwise damaging the molded article itself. Due to possible variations in the conveyor equipment, as well as possible variations in the dimensions of the molded articles themselves, the actual height of the nubs may vary. The optimum average nub height will be selected in

order to ensure substantially complete removal of the flashing globules while preventing damage to the article wall.

The fine flashing removal step is preferably carried out by a sanding or abrading process that is able to remove the remaining nubs or residual attachment strands while minimizing damage to the article proper. This is preferably carried out by means of a substantially planar sanding sheet or block that is oriented substantially parallel and coplanar to a plane defined by the upper edge of the molded article. By rapid side-to-side or unidirectional motion the sanding sheet or other abrading surface is able to sand or abrade away the residual attachment strand nubs down to the surface of the article wall without significantly damaging the article wall. Of course, some minor abrading of the article wall may actually polish and improve the surface of the article wall in some cases and can be tolerated or even preferred so long as the articles are not significantly damaged. In a most preferred embodiment, the sanding process is carried out by a belt sander that travels around in a loop to provide precision sanding in a desired plane. The foregoing apparatus comprise a preferred fine finishing subsystem.

In a most preferred embodiment, it is preferable to urge or bias the articles towards the sanding sheet or other abrasion means in order for the sanding sheet or other abrasion means to exert a desired amount of friction and abrasive action against the articles. This may be accomplished, for example, be means of flexible bristles attached to a plenum surface, which is able to intermittently raise or lower as needed to bias a group of articles against the sanding sheet. In many embodiments, the conveyor will intermittently move and then stop in order to provide a desired residence time during which the sanding sheet and articles are engaged and abrading of the residual nubs occurs. Raising up of the plenum surface and the associated bristles for a desired period of time and at a desired force results in a desired abrading force for a desired period of time in order to remove a desired amount of material from the article wall surface.

Thereafter, the plenum is lowered and the conveyor is activated to carry the finished articles away and to provide a new batch of rough finished articles to undergo sanding.

In order to complete the apparatus necessary to provide for continuous removal of flashing of newly molded articles, a conveyor will preferably be employed to continuously transport newly molded articles from the molding apparatus to the rough finishing station and from the rough finishing station to the fine finishing station. In a preferred embodiment, the conveyor will include regularly spaced apart cavities or depressions corresponding to the size and shape of the molded articles. In this way, the conveyor provides"nesting"holes or depressions for reliably maintaining the articles in

a desired location along the conveyor. As the articles are treated by the flashing-removal apparatus discussed above, the nesting holes or depressions keep the articles in place so as to ensure proper cutting and sanding without damage to, and unwanted movement by, the treated articles.

In a preferred embodiment, it will be desirable to recycle the flashing removed by the rough and fine finishing subsystems. The removed flashing fragments and dust may be evacuated from the flashing removal system by means of a suction hood or other vacuum system. The flashing fragments and dust can be recycled back into the mixer and reformed into new articles as desired. In addition, a quality control apparatus can be used to cull out and remove broken or poorly formed articles or articles of otherwise substandard quality. These culls can also be recycled together with the removed flashing.

Although the foregoing flashing removal system may be employed for a wide variety of compositions and molding systems, it is particularly well suited when used in conjunction with die mold processes involving starch-based compositions. In general, such compositions will initially include water, ungelatinized starch granules, inorganic fillers, fibers, and a gelatinized starch portion that is included to increase the viscosity and yield stress of the fluid fraction in order to ensure good fiber dispersion. Because the molding process generally results in the substantial gelatinization of the initially ungelatinized starch portion of the starting mixture, flashing fragments and containers provide an excellent source of pregelatinized starch as well as fibers and inorganic filler.

Because pregelatinized starch is generally far more expensive than ungelatinized starch granules, recycling flashing fragments and optionally molded containers themselves represents a substantial cost savings. In addition, recycling cuts down on the fiber and filler requirements.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the manner in which the above-recited and other advantages and objects of the invention are obtained, a more particular description of the invention briefly described above will be rendered by reference to a specific embodiment thereof which is illustrated in the appended drawings. Understanding that these drawing depict only a typical embodiment of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: Figure 1 is a perspective view of a newly molded"claim-shell"sandwich container that includes a substantial quantity of extraneous mechanical structures attached thereto called"flashing",

Figure 2 is a box diagram of the various components within a preferred flashing removal system equipped with means for recycling removed flashing and culled articles ; Figure 3 is a perspective view of a preferred cutting system for slicing and removing flashing structures, globules and other extraneous materials from newly molded articles ; Figure 3A is a perspective view taken along section line 3A-3A depicting the generally smooth-edged blade within the cutting system of Figure 3 ; Figure 3B is a perspective view depicting a serrated blade, which is an alternative blade configuration for use within the cutting system of Figure 3 ; Figure 4 is a side view of the cutting system of Figure 3, more particularly depicting how the severed flashing globules, stems or other extraneous features are severed by a cutting blade and carried away by means of a vacuum ; and Figure 5 is a side view of a preferred abrading system for removing any remaining nubs or other irregularities in order to yield a substantially smooth outer article surface or edge.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to novel methods and systems for finishing molded starch-bound articles, particularly the removal of flashing from newly molded containers or other articles. Starch-bound articles are typically molded from aqueous starch-based compositions using heated molds. The aqueous starch-based compositions are heated to above the boiling point of water in order to cause such compositions to expand and fill the mold cavity. Water in the form of water vapor or steam is allowed to escape from the mold by means of vent holes or other vent passages or gaps. The tremendous pressure build up within the mold also causes a quantity of the molding composition to also exit through the vent holes or vent gap, thereby yielding irregularities attached to the molded articles known as"flashing". The present invention provides methods and systems for removing such flashing.

Examples of compositions, methods and systems used to mold starch-bound articles of manufacture from aqueous starch-based compositions are set forth more fully in U. S. Patent No. 5,660,900, U. S. Patent No. 5,662,731, U. S. Patent No. 5,679,145, U. S.

Patent No. 5,683,772, U. S. Patent No. 5,705,203, U. S. Patent No. 5,709,827, U. S. Patent No. 5,776,388, U. S. Patent No. 5,783,126, U. S. Patent No. 5,843,544 and U. S. Patent No.

5,868,824. The foregoing patents are presently assigned to E. Khashoggi Industries, LLC, located in Santa Barbara, California. For purposes of disclosure, the foregoing patents are incorporated herein by specific reference.

Figure 1 depicts a newly molded"clam-shell"container having a number of unwanted irregularities in the form of flashing attached thereto. In particular, container 10 includes a top half 12 connected to a bottom half 14 by means of a hinge structure 16.

Protruding outwardly from an upper edge or rim 18 are a plurality of flashing structures 20. In most cases, the flashing structures 20 will include an enlarged globule portion 22 that is attached to the rim 18 by means of a flashing stem 24. In many cases, the globules 22 may merge together so as to form a complex globule structure 26 attached by two or more stems 24.

Whereas it may be possible to remove the flashing by merely breaking off stems 24 from the container rim 18, in many cases the stems 24 will not all break at the desired location. For this reason the present invention provides apparatus for carefully removing substantially all of the flashing, globule and stem alike, without substantially damaging the container wall or rim 18. As will be discussed more fully below, the flashing removal system preferably includes rough and fine flashing removal subsystems. The rough flashing removal subsystem preferably severs the larger globule portion from the molded article, leaving behind residual nubs or stems. Thereafter, a fine finishing subsystem is preferably used to carefully remove the remaining nubs or stems.

Figure 2 is a box diagram illustrating a preferred manufacturing system 30 according to the present invention. In particular, new materials inputs 32 such as water, ungelatinized starch granules, pregelatinized starch, fibers and an inorganic filler are provided to a mixer 34. The mixer 34 yields a desired aqueous starch-based composition which is then delivered to and fed into one or more molds 36, such as paired male and female molds. The molds define a cavity (not shown) corresponding to a desired shape of a container or other article. The molds are preferably equipped with one or more vent holes and/or vent gaps (not shown) which allow water vapor to escape and be driven from the composition in order to yield a solidified molded article. Excess mold material is typically expelled from the vent holes or gaps and thereby form flashing, which is an extraneous mass of mold material attached to the molded article (Figure 1).

In a preferred embodiment, the molded articles are conveyed to a first rough flashing removal subsystem or station responsible for removing the majority of flashing, to be discussed hereinbelow. Thereafter, the articles are sent to a second fine flashing removal subsystem or station where substantially all of the remaining nubs or flashing is removed. After that, the articles are examined by quality control means in order to remove broken or damaged articles as culls prior to further processing. Flashing fragments and dust are removed and sent to a waste materials collection subsystem.

Optionally, culled articles can also be sent to the waste materials collection subsystem.

The waste materials derived from the removed flashing and/or culled articles can be recycled back into the mixture as a source of gelatinized starch and other feed materials, such as fibers, inorganic fillers, mold release agent and other desirable admixtures. In order to maintain the proper ratio of the various materials within the mixture, one of ordinary skill in the art will be able to adjust the relative feed rates of the waste materials and new materials, respectively, in order to yield an appropriate and desired aqueous starch-based mixture.

Reference is now made to Figure 3, which is an elevational perspective view of a preferred cutting system 50. The cutting system 50 is designed to remove the majority of flashing, particularly the enlarged globule 22 and at least a portion of the flashing stem 24 (Figure 1). A conveyor 52 having individual recesses or nests 54 is preferably used to transport the molded containers from the mold apparatus to the cutting system 50. The purpose of the nests 54 is to retain a molded container 10 in a desired position during removal of the flashing. In this way, substantial mechanical forces can be applied to the molded articles during flashing removal without dislodging the articles from off the conveyor.

It should be appreciated, however, that adhesion or retention of the molded container 10 by the conveyor or other conveying means may be carried out by any container retention means known in the art. Such article retention means includes, but is not limited to, suction, electrostatic attraction, mechanical restraint, and the like.

The embodiment depicted in Figure 3 further includes a rotating band blade 56 that rotates about two or more wheels 58. The band blade 56 is preferably oriented so as to shave or slice off the flashing globules 22 and a portion of the stem 24 without damaging the upper rim 18 of the molded article 10. The depiction of a relatively smooth, toothless cutting blade on the forward edge of band blade 56 is illustrative rather than limiting. The cutting blade may have any desired and appropriate cutting edge, such as a serrated edge. A vacuum hood 60 draws the flashing fragments removed from the molded container 10 by means of the rotating band blade 56 and sends them through vacuum port 62.

It should be appreciated that the band blade 56 may be configured to have any number of cutting edges, such as a smooth but sharp edge, as illustrated in Figure 3A, or a serrated cutting edge, as illustrated in Figure 3B. The sharpness and/or depth of the serrations, if any, may be selected in order to provide optimal cutting of the particular mold material being employed. The optimal cutting surface will depend on the materials

and properties of the molded container. One of ordinary skill in the art will be able to select an appropriate cutting edge for a particular application. In most cases, a smooth but sharp cutting edge is preferred so as to effect cutting with a minimum of snagging or gouging.

Figure 4 more particularly depicts how the flashing or other irregularities are severed from the container edge or rim by means of the rotating band blade 56, as well as how the severed fragments or particles are drawn away from the molded article 10 by means of the vacuum hood 60 and out through the vacuum port 62.

The band blade 56 may be configured so as to provide a cutting edge wide enough to cut a single molded container or an entire array of molded containers. For example, the band blade 56 may be configured so as to be broad enough to cut up to eight containers or more that are arrayed side by side. Moreover, the band blade 56 is preferably adjustable so as to alter the angle and height of the cutting edge in order to fine tune the removal of flashing from a particular type of molded container or article.

Because it will generally not be desirable for the band blade to actually make contact with the edge or rim of a molded container, so as to not dislodge the container from the conveying system, the band blade 56 will preferably be adjusted so as to leave a tiny flashing stem or nub attached to the container, which is removed by a fine flashing removal substation, to be discussed hereafter. In general, it is preferable to remove as much of the flashing stem as possible without damaging the container, in this way further flashing removal is minimized.

Of course, it should be appreciated that it is certainly within the scope of the invention to provide a flashing removal system consisting solely of a cutting blade. Such a cutting blade may be oriented to slice off all or substantially all of the flashing as desired with no additional finishing or final removal step. Although it may be possible to sever all of the flashing in a single cutting or slicing step, such a process would require very close tolerances and could potentially result in an increase in the number of articles that are damaged thereby. Nevertheless, such a system, though less preferred, is certainly within the scope of the invention.

Reference is now made to Figure 5, which depicts an abrading system 70 for removing the remaining flashing nubs or stems 72 remaining on the molded container 10 after the rough cutting or slicing process. In a preferred embodiment, the fine flashing removal subsystem 70 includes a belt sander 74 which includes a sanding belt 76 that rotates about two or more wheels or cylinders 78.

The embodiment depicted in Figure 5 further includes a plenum 80 to which a

plurality of soft, flexible bristles 82 are attached. The plenum 80 is moveable so as to be capable of being selectively raised and lowered as desired in order to intermittently urge the molded containers 10 or other articles against the sanding surface of the belt sander 74. The plenum 80 may be caused to move up and down by means of a pneumatically or hydraulically driven shaft 84 or any other appropriate means known in the art. The molded containers 10 are able to rise slightly out of the nests 54 in order to provide biasing contact with the sanding surface of the belt sander 74. Upon lowering the plenum 80, the containers or other articles are able to drop back down into nests 54 in order to transport the containers 10 downstream for further processing.

The purpose of the flexible bristles 82 is to provide a gentle biasing effect of the containers against the belt sander 74 in order to provide sufficient, but not too much, force in order to create the desired amount of friction and mechanical interaction between the containers or other articles and the belt sander 74. Without the soft flexible bristles 82 it would be necessary to provide a much more exact movement of plenum 80 in order to provide adequate sanding friction but not so much that damage to the container would result. Instead of soft flexible bristles 82, any gentle biasing means known in the art may be employed, such as springs, air, vibrations, and the like.

The abrading system 70 further includes means for withdrawing or evacuating the abraded flashing dust therefrom and away from the conveyor apparatus. A vacuum hood 86 in communication with a vacuum conduit 88 is depicted in Figure 5. By providing a continuous vacuum or suction in the vicinity of the belt sander 74 the vacuum hood 86 is able to effectively scavenge and remove substantially all of flashing dust produced by the sanding action. As discussed above, the sanded flashing dust may be recycled into new containers as desired.

Where the fine flashing removal station is the only flashing removal station, as an alternative embodiment, the belt sander or other abrasion device may be set at an angled pitch (not shown) to facilitate incremental removal of the flashing. For example, as the molded container contacts belt sander, the first portion of belt sander to contact the flashing may be set at a distance that is higher than the last portion of the belt sander to contact the container. Thus, the flashing would be incrementally abraded or sanded off in stages using this approach. In other words, the height-to-width aspect ratio of the flashing would be progressively diminished between the leading edge of belt sander and the trailing edge thereof, as it encounters the molded container, until the flashing is substantially removed down to the rim. Accordingly, a belt sander that is configured to remove the flashing without the assistance of the first flashing removal station may be

understood to be an example of a combination of both the first means for removing a major portion of the flashing and the second means for removing a minor portion of the flashing not removed by the first means.

In an alternative embodiment of the present invention, a cutting blade and a belt sander may be situated under a single suction hood (not shown).

In summary, the present invention provides apparatus and systems for removing flashing and other irregularities from molded starch-bound articles which do not result in the substantial formation of divots or other depressions which can be mechanically and/or aesthetically undesirable.

The present invention also provides apparatus and systems for removing flashing and other irregularities from molded starch-bound articles which do not leave substantial quantities of burs or other raised portions which can be mechanically and/or aesthetically undesirable.

The invention further provides apparatus and systems for removing flashing and other irregularities from molded starch-bound articles which do not cause substantial fracture or other types of mechanical failure of the molded articles upon removing the flashing or other irregularities.

The invention yet provides apparatus and systems for removing flashing and other irregularities from molded starch-bound articles which provide for the recycling of such materials back into the molding compositions used to manufacture additional articles of manufacture.

The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrated and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

What is claimed is: