Stackable plastic trays
a technology of plastic trays and stackable parts, applied in the field of plastic products with improved stackability, can solve the problems of damage to the trays, the failure of previous techniques and methods to prevent this undesired phenomenon, and the effective destruction of the trays, etc., and achieve the effect of improving the stackability
Inactive Publication Date: 2011-09-22
BAKER JAY
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Benefits of technology
[0021]In general, embodiments of the present invention provide plastic products with improved stackability.
[0025]In another aspect of the invention, a plurality of stacked trays for use in storing medical devices is provided. The stack of medical trays includes first tray comprising a substantially planar flange portion extending around the perimeter of the first tray and configured to provide an engagement surface for a lid to seal, a first contour defining a first plurality of walls that at least partially define a pocket to receive a medical device, and a first plurality of separation features formed in at least some of the plurality of walls. The stack of medical trays also includes a second tray comprising: a substantially planar flange portion extending around the perimeter of the first tray and configured to provide an engagement surface for a lid to seal, and a second contour defining a second plurality of walls. The second plurality of walls have the same relative size and position within the second contour as the first plurality of walls defined by the first contour, and the second contour further defines a second plurality of separation features formed in at least some of the plurality of walls of the second tray at different relative locations from the first plurality of separation features defined in the first tray. The first tray is disposed on top of and partially nested within the second tray and each one of the plurality of first separation features engages a portion of the plurality of walls defined by the second contour at a location spaced apart from the second plurality of separation features. Additionally, the engagement of the first separation features of the second contour spaces apart other bottom surfaces of the first contour from the top surfaces of the second contour thereby discouraging adhesion between the first and second trays in the stack of trays.
Problems solved by technology
For some materials with especially high levels of surface cohesiveness such as Polyethylene Terephthalate Glycol copolymer (PETG) and Amorphous Polyethylene Terephthalate (APET), the trays will adhere to one another with such force that the effort required to separate them can result in damage to the trays and in some cases the effective destruction of the tray.
Previous techniques and methods employed to prevent this undesired phenomena have had limited success and introduce other problems.
A common problem with conventional de-nesting lugs is reduced manufacturing efficiency because the de-nesting lugs have a “negative draft angle.” Typically, for a formed tray to be successfully extracted from a mold, a significant percentage of the geometry of the tray and likewise the mold upon which it was formed, must exhibit what is conventionally known as “positive draft angle.” A positive draft angle is the geometry of the finished plastic tray where the tangential relationship of vertical features of the tray to a horizontal plane across a common base of the tray is greater than 90°.
In some cases, this geometry of the de-nesting lug may be destroyed in the de-molding process if the profile is overly aggressive in its degree of negative angle and / or relative size.
In addition, if too many de-nesting lugs have been formed into the finished tray, the tray may be destroyed due to the sheer force required to extract the tray from the mold even if any given de-nesting lug by itself would not have resulted in damage.
Actuated mold geometry for plastic trays manufactured for disposable end-use applications, such as medical trays, deli trays, etc., is extremely rare due to the added cost, complexity and maintenance requirements of such mold tooling.
But even in circumstances where the negative economic impact of such complex tooling could be justified, frequently the required finished geometry of the plastic tray itself makes such an approach incompatible with the functionality of the finished product.
Another disadvantage to the use of “negative degree” de-nesting lugs is the unintended locking effect that can occur on a stack of plastic trays when a downward force has been exerted on the stack of trays.
This variability can create negative results in the finished tray.
Even if the topical application of the silicone is consistently applied, the effects of gravitational pull can cause the silicone to gravitate downward on the surface of the coiled plastic rolls such that over time there can be a noticeable accumulation of silicone on the lower portion of the plastic roll.
These internal release agents propagate to the surface of the sheet; however, the efficiency of this solution has not been proven and the negative impact of release agents on the surface of the finished tray still exist.
The lid is typically gas permeable, but its structure is such that while gases may pass through, bacteria and viruses cannot.
The presence of a topical release agent on the surface of the tray can negatively affect the integrity of the seal.
Due to the previously discussed variability inherent to the application of these topical release agents, the medical device manufacturer can experience unpredictable variations in the quality of their sealing process.
As a result, the manufacturer may experience higher inspection costs requiring destructive testing of sealed trays and an increased risk of field failures and product recalls.
Method used
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[0034]The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the inventions are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.
[0035]In various embodiments of the present invention, trays with mechanical separation features are provided that reduce the adhesion between adjacent trays in a stack of at least partially nested trays or other plastic products. The separation features formed in the trays are strategically located to reduce contact between one tray's bottom surface from the top surface of the tray beneath it. In various embodiments, this is accomplished by employing a plurality of different tray designs, e.g., “A design” and ...
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In various embodiments of the present invention, trays with mechanical separation features are provided that reduce the adhesion between adjacent trays in a stack of at least partially nested trays or other plastic products. The separation features formed in the trays are strategically located to reduce contact between one tray's bottom surface from the top surface of the tray beneath it. In various embodiments, this is accomplished by employing a plurality of different tray designs, e.g., “A design” and “B design.” The different tray designs have substantially the same size and contour except for the location of the separation features. To prevent adhesion between the trays when stacked, the different tray designs are alternated when stacked (e.g., A design, B design, A design, B design) and the separation features reduce the nesting depth of adjacent trays.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of U.S. Provisional Application No. 61 / 314,359, filed Mar. 16, 2010, which is incorporated herein by reference in its entirety.FIELD OF THE INVENTION[0002]Various embodiments of the present invention relate to plastic products with improved stackability.BACKGROUND OF THE INVENTION[0003]Certain thermoplastic materials exhibit high degrees of surface cohesiveness. When these thermoplastics are fabricated into various finished products such as medical trays for disposable instruments, the products produced from these thermoplastics may adhere to each other as the products are nested together at the end of the fabrication process. As used herein, the terms “products” and “trays” may be used interchangeably.[0004]The high degree of surface cohesiveness exhibited by many thermoplastics results in formed trays, which have been “nested” together to reduce the total volume of space required for storage and shipm...
Claims
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CPCA61B19/0271A61B2019/0275B65D21/0233B65D1/36A61B2019/0277A61B2050/3006A61B2050/3007A61B50/33
InventorBAKER, JAY
OwnerBAKER JAY