1 STACKABLE NETAL BASKET This invention relates to a sLackable metal basket. The invention has particular application to a stackable metal basket which can be autoclaved 2nd/or chemically sterilised 5 such as, for example, by eLhylene oxide, substantially without loss of mechanical integrity. The stackable metal basket of the present invention is also intended for use with existing racking systems by way of which baskets may be supported by a lip on their upper rear edges. However, the stackable metal 10 basket of the present invention may be used in applications which do not require sterilisation and are not confined to baskets which can be supported on existing racking systems. Stackable, rackable baskets of plastics material have been provided and are sometimes very convenient for storage of 15 goods or materials which require ease of access thereto. However, the application of such systems has been limited due to the limitations of the plastics material from which the baskets are formed, thereby precluding such systems for use in applications in which the contents of the baskets require 20 sterilisation, such as by autoclaving or exposure to sterilising chemicals such as ethylene oxide and such like. The limitations of baskets according to the prior art also include hot objects and/or objects whose material of construction is chemically incompatible with the plastics 25 material of the baskets. In this specification, for convenience, terms such as upper, lower, vertical, top and bottom may be used to refer to the stackable metal baskets of the present invention in its normal orientation and are not to be taken to limit Lhe 30 baskets of the invention to any particular orientation. The present invention aims to provide a stackable metal basket which alleviates one or more of the aforementioned 2 problems. Other aims and advantages of the invention may become apparent from the following description. With the foregoing in view, in one aspect the present invention resides broadly in a stackable metal basket 5 including: a base and sidewalls extending upwardly from the base to define an open top, and wherein: said base and said sidewalls are formed from perforated metal sheeting without a perimeter frame; and L. said sidewalls include top edge portions coincident with a plane substantially parallel to said base, said top edge portions including opposed portions having a smaller separation than the edges of the base from which said sidewalls extend. 15 Preferably, the base is square or rectangular and the sidewalls are also square or rectangular, the sidewalls including the opposed sidewalis, a front wall and rear wall. It is preferred that the opposed side walls extend substantially at right angles from the base and the base is 20 slightly wider than the spacing between the upper edges of the opposed sidewalls. The opposed sidewalls are preferably substantially planar and slope slightly inward to provide the closer spacing of the edges as hereinbefore described. The rear and side edges of the base may also include formations 25 which enable the stacking of one basket upon the other without the upper basket slipping sideways into the one below. Preferably, the base is recessed upwards to form a lip or skirt which fits over the top edge of the basket below when the baskets are stacked one atop the other. Preferably, the 30 skirt does not extend across the bottom of the front wall. Preferably, the rear wall extends substantially at right angles to the base, but the front wall extends at an obtuse angle from the base and has its upper edge terminating lower than the upper edges of the opposed sidewalls to provide a 3 front opening between stacked baskets when stacked one upon the other. It is also preferred that the upper edge of the rear wall be at least the same height as the opposed sidewalls or include a projection which prevents an uppcr basket of a 5 stack being slid backwards with respect to the basket upon which it is stacked. In a preferred form, the upper edge of the roar wall includes a formation, such as a lip, formed to engage with a racking system, such as, for example, louvre racking systems 10 according to the prior art. In such form, it is preferred that the stackable, rackable baskets according to the present invention be provided in a range of modular sizes comnensurate with the sizes of the baskets of racking systems of the prior art. 15 Preferably, the base and sidewalls are formed from metallic mesh material. For applications which arc not critical for sterile environments, wire mesh may be used. However, it is preferred that the base and sidewalls are formed from perforated metal sheeting, the term perforated as 20 used herein incorporating wire mesh sheeting as used herein unless the context indicates otherwise. In such form, the base and sidewalls are folded from a pattern, the perforated metal sheeting being of a gauge sufficient for the basket to be self-supporting without a perimeter frame, that is, a frame 25 formed from wire or such like. Preferably, the perforations are cut on a pattern at regularly spaced intervals, leaving regions of non-perforated material in the vicinity of the folds, seams and edges of the basket. Preferably, the perforations are cut on a 30 substantially square pattern. Although the base is not necessarily perforated, it is preferred that perforations be included in the base to provide drainage of water which may otherwise accumulate in the autoclaving process.
4 In order that the invention may be more readily understood and put into practical effect, an exemplary embodiment of the present invention will now be described with reference to the following drawings, and wherein: 5 Fig. I is a photographic view of a small stackable, rackable basket according to the invention; Fig. 2 is a photographic view of an intermediate stackable, rackable basket according to the invention being larger than the basket illustrated in Fig. 1; 10 Fig. 3 is a photographic view of a large stackable, rackable basket according to the invention being larger than the baskets illustrated in Figs. 1 and 2; Fig. 4 is a photographic view of two large stackable, rackable baskets of Fig. 3 in a stacked configuration 15 with respect to one another; Fig. 5 is a photographic view of the large stackable, rackable baskeL of Fig. 3 with two dividers mounted therein; Fog. 6 is a photographic view of two intermediate 20 stackable, rackable baskets of Fig. 2 in stacked configuration, and having a divider mounted in the upper basket; Fig. 7 is a photographic view of eight stackable, rackable baskets of varying size mounted to a louvre 25 racking panel; and Fig. 8 is a photographic view from above of a wire mesh stackable, rackable basket according to the invention. In Figs. 1 to 7, the same reference numerals are used to indicate like elements irrespective of the size of the basket 30 being illustrated and described. The stackable, rackable baskets 10 illustrated in Figs. 1 to 7 each include a base 11, 5 two opposed sidewalls being a left sidewall 12 and a right sidewall 13, a rear wall 14 and a front wall 15. The left and right sidewalks progressively larger from the small, through the intermediate to the large baskets, and the front and rear 5 walls are correspondingly larger as well. The left sidewall extends upward from a left bottom edge 16 along the left edge of the base to a left top edge 17. Tn a corresponding fashion, the right sidewall extends upward from a right bottom edge 18 along the left edge of the base to a 10 right top edge 19. The width of the base between the left and right bottom edges is from 3 to 5 mm wider than the spacing between the left and right top edges. Additionally, the left and right bottom edges are longer than the left and right top edges. 15 The front wall slopes outward from the base and Lerminates with a front lip 20 along the front upper edge 21, the front upper edge being lower than the left and right upper edges so that the front wall in shorted in height from the base. A front side edge 22 extends substantially straight, but 20 at a backward sloping angle, from each end of the front upper edge to provide a pentalateral shape of the opposed sidewalls. The rear wall has an upper rear edge 23 with a lip or loop (not shown) by which the basket or baskets may be removable mounted to a louvre panelled rack 24 illustrated in Fig. 7. 25 The baskets illustrated in Figs. 5 and 6 include vertical dividers 25, two in the large baskets of Fig. 5 and one in the intermediate basket of Fig. 6. The wire mesh basket 30 illustrated in Fig. 8 is similar in configuration to the baskets of Figs 1 to 7, particularly 30 the intermediate basket of Fig. 2. It can be seen that the base and sidewalls are formed from panels of woven wire mesh, each panel being surrounded by a peripheral wire frame shown typically at 31 . A wire loop 32 extends along the top edge of the rear wall of the basket, predominantly substantially 6 parallel thereto to provide a slot 33 into which the tongue of a louvre may be inserted for supporting the basket on a louvre panelled rack of the same form as that illustraLed in Fig. 7. The perforated sheet baskets of the present invention may 5 be formed from two pieces of metal, preferably medical grade stainless steel, sheeting. One piece is folded to form the rear and opposed side walls and the other folded to form the base and front wall. The perforations are formed into the sheeting, preferably by use of a turret punch, the method of 10 perforation being selected to minimise sharp cdges about the periphery of the perforations. Preferably, the punching is provided according to a predetermined program for each size of basket. The folding method also provides the stacking ability, the back and sides being folded such that the base is 3 to 5 15 mm wider than the top. The absence of the wire frame in the perforated sheet version conforms with the requirements necessary for sterilisation by autoclave, there being no crevasses, creases or cracks in the design in which potentially pyretic, it not 20 infectious, material may be lodged. The size of the grid pattern for the perforations is selected to be small enough to avoid small objects becoming trapped, thereby avoiding the possibility of sterile packaging being damaged when being removed from the basket, but large enough to minimise the 25 surface area. It is believed that the perforated sheeting form of the present invention satisfies infection control standards. Additionally, the baskets of the present invention may be stacked without clips or intervening stacking fasteners. 30 One or more baskets of the present invention may filled or partly filled with goods or materials to be autoclaved. The wire mesh form of the baskets may be autoclaved, but not necessarily in applications requiring sterility. The baskets of perforated metal sheeting may be sterilised by autoclaving, 7 the one-piece design having no crevasses in compliance with infection control and/or hygiene or GMP standards for sterile goods manufacturing. In hospital use, in particular, the sterilised goods may then be drawn directly from the basket, 5 thereby providing medical surgical operations with sterilized or resterilised implements or such like. Although the invention has been described with reference to a specific example, it will be appreciated by persons skilled in the art that the invention may be embodied in other 10 forms within the broad scope and ambit of the invention as herein set forth and defined by the following claim.