AU9716901A - Pressure forming item stacking improvement - Google Patents

Description

52320 HKS:ZS P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name of Applicant: GRAHAM MAXWELL BROWN Actual Inventor: GRAHAM MAXWELL BROWN Address for Service: COLLISON CO.,117 King William Street, Adelaide, S.A. 5000 Invention Title: PRESSURE FORMING ITEM STACKING IMPROVEMENT Details of Associated Provisional Applications: AUSTRALIAN Provisional Patent Application No. PR2028 dated 13th December 2000 The following statement is a full description of this invention, including the best method of performing it known to me: This invention relates to items manufactured from plastic material by pressure forming.

It is currently known in the manufacture of an article including a tapering shape which is intended to nest with like articles in a stacking relationship, to project a portion of the wall into a lug which is shaped and positioned so as to adequately intersect an upper edge of a further of the items.

This provides that the one item when stacking into another or nesting into another is kept separated by surfaces which are substantially transversely aligned to a stacking direction which ensures that the items or articles will easily separate rather than jammed together.

A current problem with such an arrangement however, is that in the method of forming such a lug, this has traditionally been formed so as to provide a lower engaging surface which projects directly out from the alignment of the wall providing a remainder of the side or the comer of the item.

o o 1 5 The extent to which this so called stacking lug must be outwardly located, means that, with a pressure forming method such as vacuum forming, the thickness of the sheet therefor providing this stacking supporting surface provided by the lug S. becomes very thin indeed.

The problem with this being very thin then is that if a stackable item is stacked 20 where there are a large number of such items stacked one upon the other, then there can be considerable pressure exerted on the stacking lug so that where this is at the bottom of such a stack, it is found that this then causes a collapse of this and the stackable items can then revert to inter engaging of tapering shapes so that these then jam together.

This then causes significant problems where the items are to be subsequently fed into an automatic machine and being separated by some automatic process, or even if they are to be manually separated, it becomes a lot harder to separate these and it is a significant problem in the industry.

In accordance with this invention, there is proposed a stackable item formed by pressure forming from a plastics sheet material, having, in relation to an outwardly 3 extending stacking lug, an outward deformnation of the wall of the material immediately below a stacking engaging surface of the stackable lug so that there is an outward deviation of material immediately below this stackable lug but not quite to an extent of the portion immediately above the stackable surface being the stackable lug.

The result of this modification in shape is that by having more of the sheet material closer to the most outwardly extended portion of the stackable lug, some of the thickness of the sheet is derived from stretching of the material from below as well as slightly more from above but with the result that there is a significant improvement in the overall thickness of the most outstanding portion of the stackable lug.

In preference the pressure forming is vacuum forming of a heated plastics sheet.

0. In an altemrnate preferred arrangement the invention can be said to reside in A •stackable item in which a stackablelug has an outward deformation of the wall of the S. 15 material of the item immediately below a stacking engaging surface of the stackable lug such that an extent of outward deviation of material immediately below this stackable lug is not quite to an extent of the portion immediately above the S* stackable surface being the stackable lug so as to thereby leave a narrow ledge to act as the stacking engaging surface.

20 In a further form the invention can be said to reside in two stackable items where one of the items is stacked on a second of the items where each item is as previously described where each item has an identical shape, which shape has a rectilinear shape in plan and at each of its outermost comers, an outwardly extending stackable lug with an outward deformation of the wall of the material immediately below a stacking engaging surface of the stackable lug so that there is an outward deviation of material immediately below this stackable lug but not quite to an extent of the portion immediately above the stackable surface being the stackable lug.

In a typical instance, which is a preferred instance only, a plurality of integrated containers for instance formed from a sheet of plastics material by vacuuming forming, has an overall rectangular shape in plan and at each of the outermost four comers, there is provided an outwardly extending stackable lug having a 5 degree undercut so that it projects effectively past an intersecting shape for stacking 4 purposes with respect to an identical article with which it is nested in a stacking relationship.

The wall of the comer can be aligned at 6 degrees to the vertical whereas a portion immediately below the stackable lug is aligned at 13 degrees to the vertical but so as to leave however an outermost horizontal abutting surface which is further provided by a stacking lug formed by the wall immediately above the stacking surface being a negative 5 degrees.

For a better understanding of this invention it will now be described with the assistance of drawings wherein: Figure 1 is an undemrneath perspective view of a stackable item appropriate for incorporation of the invention where it is formed from sheet plastics material formed vacuuming forming; Figure 2 is a perspective view of the same item as in Figure 1 viewed from above; 15 Figure 3 is a plan view from below of the item as shown in Figures 1 and 2; Figure 4 is a portion of two of the items as shown in Figures 1 through 3 when in a stacking position one upon the other; and Figure 5 is generally the same elements as in Figure 4 being separated portions of the item as in Figures 1 to 3 when viewed from the side inside elevation.

20 Referring in detail to these drawings, there is an item 1 being a tray which includes a wall and a floor which provide a rectangular shape in plan and which is formed from "a sheet of plastics material by being heated and then being pressure formed generally by drawing the material into a shaped mold by vacuum forming into the shape shown.

This shape includes a plurality of containers 2 which are integrally formed and each include a wall aligned so that there is provided a tapering shape where the angle of taper to the vertical when the item 1 itself is sitting on a horizontal surface, is six degrees.

In each of the outermost comers of the item in total shown typically at 3 there is formed a stacking lug 4.

This is provided by an uppermost portion at 5 being aligned to the vertical by having a negative 5 degree undercut shape resulting in a lowermost abutting surface 6.

What is distinctive here however is that immediately below this surface 6 is a further outwardly extending portion 7 which deviates from the general alignment of the wall of the container shape 2, so as to project more extensively and therefore in effect narrow the depth of the ledge or surface 6 providing thereby a narrow ledge which then acts as a stacking engaging surface. This reduces any localized stretching of the sheet material and therefore assists in a general thickness of the material providing the stacking engaging surface and surrounding supporting material.

The result of this is that the amount of stretch of plastics material needed to provide for the outward extent of projection of the abutting surface 6 is lessened by there now being more material immediately below which can contribute to the material -requirement needed.

This then results in a significantly thicker wall being formed in the immediate location 15 of the abutting surface 6 and the surrounding portions and the result is that it is then very much easier or indeed in practice very effective in providing a much stronger abutting surface.

In fact, the extent to which this then thickens the abutting surface is such that such stacking items then will reliably stay apart even under relatively substantial stacking 20 pressures.

The result of this is then that there is very much increased reliability in terms of being able to separate such stackable items and this means that they can be left in automatic separating machines with a great deal more reliability than has hitherto been available.

While the invention has been described specifically with respect to one stackable item, this is given by way of illustration only and it is not intended in any way that this should be considered as the only way in which this invention can be put into practice.

Any item formed from pressure forming which can mean typically vacuum forming can be appropriately modified by using this additional deviation concept immediately below a stacking surface so as to provide closer supply of material to 6 stretch into the extended stacking shape which normally is intended to take a stacking load.

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Claims (2)

1. A stackable item formed by pressure forming from a plastics sheet material, having, in relation to an outwardly extending stacking lug, an outward deformation of the wall of the material immediately below a stacking engaging surface of the stackable lug so that there is an outward deviation of material immediately below this stackable lug but not quite to an extent of the portion immediately above the stackable surface being the stackable lug. V"1 0 2. A stackable item as in the immediately preceding claim further characterized in that the pressure forming is vacuum forming of a heated plastics sheet. i' 3. A stackable item in which a stackable lug has an outward deformation of the S:wall of the material of the item immediately below a stacking engaging surface of the stackable lug such that an extent of outward deviation of •1 5 material immediately below this stackable lug is not quite to an extent of the S" portion immediately above the stackable surface being the stackable lug so as to thereby leave a narrow ledge to act as the stacking engaging surface. Two stackable items where one of the items is stacked on a second of the items where each item is as in any one of the preceding claims where each o 20 item has an identical shape, which shape has a rectilinear shape in plan and at each of its outermost comers, an outwardly extending stackable lug with an outward deformation of the wall of the material immediately below a stacking engaging surface of the stackable lug so that there is an outward deviation of material immediately below this stackable lug but not quite to an extent of the portion immediately above the stackable surface being the stackable lug. Two stackable items where one of the items is stacked on a second of the items where each item is as in any one of the preceding claims where each item has an identical shape, which shape has a rectilinear shape in plan and at each of its outermost comers, an outwardly extending stackable lug characterized in that there is an outward deformation of the wall of the 8 material of the item immediately below a stacking engaging surface of the stackable lug such that an extent of outward deviation of material immediately below this stackable lug is not quite to an extent of the portion immediately above the stackable surface being the stackable lug so as to thereby leave a narrow ledge to act as the stacking engaging surface.

6. A stackable item characterized by a stacking lug which is substantially as described in the specification with reference to and as illustrated by the accompanying illustrations. Dated this 12th day of December 2001 GRAHAM MAXWELL BROWN By his Patent Attorneys COLLISON CO *ee