WO2013181698A1

WO2013181698A1 - Recyclable mail tray

Info

Publication number: WO2013181698A1
Application number: PCT/AU2013/000592
Authority: WO
Inventors: Henry Erwin Spira
Original assignee: Agressor Corporation Pty Ltd
Priority date: 2012-06-05
Filing date: 2013-06-05
Publication date: 2013-12-12
Also published as: AU2013271340A1

Abstract

The present invention relates to a recyclable mail tray, used to store mail articles that are sorted into various postal areas by a postal service, which is easily recycled without the need to disassemble each tray into its various components. The present invention also relates to a mail tray that is lightweight and can provide an improved stiffness to weight ratio than previously known solutions.

Description

RECYCLABLE MAIL TRAY

BACKGROUND OF THE INVENTION

The present invention relates to trays used to store postal items, such as envelopes and parcels, during a mail sorting process. The invention particularly relates to a recyclable and light weight mail tray whereby the entire tray may be recycled without any disassembly steps to separate materials.

For a considerable number of years mail items have been sorted into various trays or boxes to enable a postal service to categorise items according to a destination postal area or zone. Mail trays, commonly known as totes, are typically a box-like article adapted to be used by conventional mechanised mail sorting systems to store mail items that correspond with the postal area a tray is labelled as travelling to. Each mail tray is expected to be able to be used for a considerable length of time before failure and accordingly is required to be substantially durable to the consistent impacts it will undergo during handling by machinery and users. Furthermore, mail trays are increasingly used during the transport of mail by airfreight, where the weight of each tray contributes towards fuel consumption and transport costs.

Totes are typically constructed from a corrugated plastic sheet, cut into a net, or blank, which comprises a base and four sidewalls, and folded into an open top box structure. A metal, typically steel, rim is fixed around the perimeter of the opening of the box to prevent the sidewalls from separating from each other and provide the necessary rigidity for the box to withstand impacts during use. Whilst this type of construction has proven an acceptable solution for many years, it suffers a number of drawbacks including being heavy and thus unpopular for use during airfreight journeys. Such mail trays are also difficult to recycle as a user must separate the two materials prior to recycling, requiring considerable effort to separate the plastic sheet from the steel rim. Furthermore, when a tote of this construction undergoes a significant impact, the metal rim is often plastically deformed, permanently damaging the structure of the box and rendering it useless. International PCT application no. WO 1999/005030, entitled "Method for butt-jointed assembly of two sheets and use of said method for making a container" offers some improvement to known mail tray concepts by using exclusively plastic materials to form a reinforced box-like container, the solution having a plastic sheet material net folded into a box and reinforcing ribs placed along each vertices and two of the top edges. However, such a solution suffers from a lack of rigidity in all three planes that an impact may be inflicted on the tray and as such, is prone to collapse during use and transportation.

Australian patent no. 2009101281, entitled "Reinforced Storage Container" offers an alternative solution to known tote containers disclosing a container which comprises a body formed from corrugated plastic sheeting and a four-sided closed loop rim made of a plastic material. Such a solution is lighter than typical metal rim mail trays and is entirely recyclable, without any need to disassemble the box. However, such a solution can lack rigidity throughout its lifespan and in situations where fuel availability is scarce, is considered too heavy.

Accordingly, it would be desirable to provide a recyclable mail tray that substantially alleviates or overcomes one or more of the known disadvantages of existing techniques or that may provide a useful alternative to them.

BRIEF SUMMARY OF THE INVENTION

According to one aspect of the invention, a recyclable mail tray is provided that comprises: a main body, having a base and a plurality of side-walls which enclose an opening, the main body being made from a recyclable material; and a rim, distally located from the base and retained around the perimeter of the opening, the rim being made from the same recyclable material as the main body; whereby the rim prevents each side-wall from moving away from each other and is formed from a substantially hollow tubular member.

According to the preferred embodiment, the main body is made from a corrugated plastic sheet material, preferably being polypropylene. In accordance with an alternative embodiment, the constituent parts of the main body are formed by folding a flat sheet of material. Preferably in such an embodiment at least a portion of each side-wall is folded to create a cavity in which the rim is located.

Preferably, the side-walls of the invention are fixed to each other or themselves by ultrasonic welding.

According to another aspect of the invention the rim is formed as a closed loop and adapted to closely follow the perimeter of the opening of the tray.

In the preferred embodiment the rim has a circular cross-sectional profile.

In this specification, unless the context clearly indicates otherwise, the term "comprising" has the non-exclusive meaning of the word, in the sense of "including at least" rather than the exclusive meaning in the sense of "consisting only of". The same applies with corresponding grammatical changes to other forms of the word such as "comprise", "comprises" and so on. BRIEF DESCRIPTION OF DRAWINGS

The invention is now discussed with reference to drawings, where:

Figure 1 is a top view of a flat blank of sheet material used to construct a mail tray;

Figure 2a is a perspective view of a rim in accordance with a first embodiment;

Figure 2b is a cross-section of the rim along the line A-A in accordance with Figure 2a; Figure 3a is a perspective view of a rim in accordance with a first embodiment;

Figure 3b is a cross-section of the rim along the line B-B in accordance with Figure 3a;

Figure 4 is a perspective view of the blank of sheet material folded into a box-like structure;

Figure 5 is a perspective view of the blank folded into a box-like structure with the rim in position;

Figure 6 is a perspective view of a complete mail tray unit;

Figures 7a to 7f and Table 1 and Table 2 show a series of photographs of a deformation/compression test of a conventional mail tray with a steel rim;

Figures 8a to 8f and Tables 3 and Table 4 show a series of photographs of a deformation/compression test of a mail tray in accordance with an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

In general, the present invention concerns a recyclable mail tray, used to store mail articles that are sorted according to destination by a postal service, which is easily recycled without the need to disassemble each tray into its components, The present invention also relates to a lightweight mail tray that includes an improved stiffness to weight ratio rim when compared to previously known solutions, offering durability advantages.

In the preferred embodiment and shown in figure 1, the invention comprises a mail tray formed from a flat net or blank of corrugated plastic material 1 that includes a base portion 2 and four sidewall portions 3. Preferably the net of material is made of polypropylene, such as Fluteboard^®, however other recyclable materials should be appreciated to be within the scope of the invention.

Turning to figure 2a, the invention also includes a reinforcing rim 4, formed into a closed loop, configured to fit around the perimeter of the tray. It can be seen in the cross-section of the rim shown in figure 2b that the rim is preferably circular in cross-section and formed by an extrusion process. However, other cross-sectional profiles and production techniques may be used according to the requirements of the mail tray. In particular, as shown in figures 3a and 3b, a triangular cross-sectional profile is a preferable alternative due to the inherent stiffness of a triangular structure.

In both embodiments, the rim is also preferably formed from polypropylene to enable the entire unit to be recycled without any disassembly process steps to separate materials. Of course, if the sheet material used is of a different material to polypropylene, it is within the scope of the invention that the material of the rim is also modified to be complimentary to the sheet material used. This is an important aspect of the invention, that the rim material and the sheet material are either the same or complimentary materials to allow for the mail tray to be recycled without the need to disassemble the tray to separate the rim from the sheet material. The rim is also hollow, having an annular shell 5 and central hollow region 6 which preferably extends throughout the length of the rim, the dimensions of which may be modified according to weight and structural requirements. The rim 4 is also preferably made from a thermoformable plastic having a plastic memory, whereby the rim returns to its original shape should a significant impact be inflicted on the rim during use.

Polypropylene is a preferred material because it is easily recycled and is both lightweight and strong. In particular, polypropylene has a "shape memory", which usefully minimises the likelihood of permanent plastic deformation, in the event of a large stress force being applied to the rim of the mail tray, which could permanently damage the structure of the box and render it useless.

Figures 7a to 7f and 8a to 8f and Tables 1 to 4 show a series of comparative deformation/compression tests between a convention mail tray with a steel rim and a mail tray of the present invention comprising a substantially hollow polypropylene rim. These tests were carried out in Sydney on 4 June 2013 by Enersol Pty Ltd, an ISO9001: 2000 rated testing laboratory accredited by NATA, compliant with the requirements of ISO/IEC 17025 (2005). As shown in the results, in the compression tests a series of deformative compression forces were applied to both the conventional mail tray and the mail tray of the present invention. The amount of compression applied to each mail tray was 0cm, 5.5cm and 12.5cm medially and 0cm, 7.5cm and 12,5cm laterally. As shown in the results in Figures 7a to 7c, following the application of this medial compression force, the conventional mail tray obtained a permanent set of Ocm, 1.0cm and 4.6cm respectively. As shown in Figures 7d to 7f, following the application of this lateral compression force, the conventional mail tray obtained a permanent set of Ocm, 1.9cm and 5.0cm respectively. On the other hand, as shown in Figures 8a to 8c, following the application of this medial compression force, the mail tray of the present invention obtained a permanent set of 0cm, 0.2cm and 0.6cm respectively. As shown in Figures 8d to 8f, following the application of this lateral compression force, the conventional mail tray obtained a permanent set of 0cm, 0.2cm and 0.4cm respectively, Figure 4 illustrates the first stage of constructing a mail tray in accordance with the preferred embodiment of the invention, wherein each side-wall 3 is folded upwards, to be substantially perpendicular to the base 2. Following this, and shown in figure 5, a rim 4 is positioned around the outside surface of each side-wall 3 and at least a portion of each side-wall 7, is folded downwards, trapping the rim within the cavity created by the folded portion of the side-wall, and joined to the outside surface of each wall. The rim 4 therefore provides a retaining ring around the perimeter of the opening, preventing each side-wall 3 from moving away from each other and increasing the rigidity of the box-like structure. As shown in figure 6, preferably the folded portions of the side-walls 7 are fixed to themselves or each other 3 by an ultrasonic welding process, however, other joining techniques, such as riveting, may be suitable dependent on the requirements of the mail tray. However, in the interest of minimising the weight of the mail tray, ultrasonic welding is most preferred. The rim 4 may also be affixed around the perimeter of the opening created by the side-walls 3 by a number of other means, for example by an adhesive or welded in place, wherein the rim is not retained within a cavity created by folding a side-wall yet still provides a retaining rim that prevents the side-walls 3 from separating form each other. The invention is generally of the same dimensions as totes commonly in use in order to be compatible with conventional mail sorting machinery and processes. However, it will be appreciated by those skilled in the art that the maii tray may be adapted to a wide range of dimensions in order to suit its purpose. Due to the rim 4 having a hollow region 6, the present invention offers a number of distinct advantages in relation to the weight and rigidity of a mail tray when compared with conventional mail trays. For example, a mail tray in accordance with the present invention that has a rim of an equivalent cross-sectional diameter to known metal or plastic rim prior art solutions requires less material in its construction and consequently weighs less.

In other instances where rim cross-sectional diameter is limited within tolerances imposed by mail tray handling machinery requirements, where a small increase in diameter is permissible, for example by l-2mm, the rim is noticeably stiffer than solid cross-section plastic rim alternatives and provides a rigidity that is closer to metal rim solutions, whilst being substantially lighter. A further advantage of a substantially hollow rim, and particularly one made from polyethylene, is that it will retain its shape more readily than a metal rim when a compressive stress force is applied. Furthermore, in instances where the rim cross-sectional diameter is able to be more substantially increased, when compared with a solid cross-section rim of equal mass, of either plastic or metal material, the increase in stiffness of the rim due to the inherent properties of a hollow tubular construction is significant, and substantially increases the rigidity of the box. Accordingly, the properties of the hollow rim 4 can be modified according to the requirements of the mail tray and provide improvements to the weight and/or the durability of the tray during impacts, when compared to prior art solutions. Following this approach, it is possible to provide a mail tray that is light weight (particularly when compared with conventional metal rimmed trays), can be easily recycled, and can have a dimensionally thicker rim (which would increase the stiffness and durability of the mail tray) but retain the lightweight characteristics.

In the preferred embodiment of the invention, an entire mail tray unit is significantly lighter than those commonly used in the industry. For example, a typical steel rim mail tray weighs 720g, which includes a 4mm cross-sectional diameter rim which weighs 220g. The present invention, when constructed according to identical dimensions and using an 8mm cross-sectional diameter plastic rim, weighs only 600g. The preferred embodiment of the present invention therefore provides a mail tray which has a comparable rigidity to conventional steel rim models however, offering a weight saving of approximately 17%. This is a significant weight saving and provides substantial advantages in providing a mail tray that is readily recyclable, utilises less material for construction and provides a transportation advantage given its reduced weight.

Although the invention is described above with reference to specific embodiments, it will be appreciated by those skilled in the art that it is not limited to those embodiments and may be embodied in other forms.

Claims

CLAIMS:

1. A recyclable mail tray comprising : a main body, having a base and a plurality of side-walls which enclose an opening, the main body being made from a recyciabie material; and a rim, distally located from the base and retained around the perimeter of the opening, the rim being made from the same recyclable material as the main body; whereby the rim prevents each side-wall from moving away from each other and is formed from a substantially hollow tubular member.

2. A recyclable mail tray in accordance with claim 1 wherein the body is made from a corrugated plastic sheet material.

3. A recyclable mail tray in accordance with claim 1 wherein the body is made from polypropylene.

4. A recyclable mail tray in accordance with claim 1 wherein the constituent parts of the main body are formed by folding a flat sheet of material.

5. A recyclable mail tray in accordance with claim 4 wherein at least a portion of each side-wall is folded to create a cavity in which the rim is located.

6. A recyclable mail tray in accordance with claim 5 wherein the side- walls are fixed to each other or themselves by ultrasonic welding.

7. A recyclable mail tray in accordance with claim 1 wherein the rim is formed as a closed loop and adapted to closely follow the perimeter of the opening.

8. A recyclable mail tray in accordance with claim 1 wherein the rim has a circular cross-sectional profile.

9. A recyclable mail tray in accordance with claim 8 wherein the rim has a diameter of about 8mm and the total weight of the mail tray, including the rim, is about 600g.

10. A recyclable mail tray in accordance with claim 9 wherein the total weight of the mail tray, including the rim, is about 17% less than a mail tray having a metal rim.

11. A recyclable mail tray in accordance with claim 1 wherein the rim has a triangular cross-sectional profile.

12. A recyclable mail tray in accordance with claim 1 wherein the rim is able to substantially recover its original shape following the application of a distortional force thereon.