1 ATTACHMENT DEVICE Technical Field [0001] The present invention relates to an attachment device and particularly relates to, but is not limited to, an attachment device for attaching a tag to a package such as a cotton bale. Background of the Invention [0002] Bales of processed cotton have individual characteristics such as weight, variety and quality. A unique identifying number is allocated to each bale during the ginning operation. This is displayed on the bale using a numbered hanging tag with both human readable and machine-readable bar codes. A current method of attaching these tags to cotton bales is by using a flexible piece of wire. The wire is threaded through a hole in the tag, bent back through 180 degrees and both ends are then threaded through the weave of the fabric bag, and finally twisted back onto itself several times. [0003] The several seconds required to perform this operation have an impact on the throughput of the ginning operation. Even if the actual ginning speed isn't greatly affected, the haste in carrying out the task combined with boredom and fatigue during long shifts can lead to the tag not being attached securely and separating from the bale. The characteristic of the two ends of the wire being threaded together through a woven fabric often leads to the ends of the wire catching on the threads, and several attempts may be needed before it passes through. [0004] The present inventor has previously developed a plastic tie for securing tags to cotton bales. However the bales that have historically been made from coarse hessian have more recently been replaced by bales made from a more closely woven cotton fabric. The previously developed thick plastic ties are not able to be readily threaded through the closely woven cotton fabric bales. [0005] A problem common to both previous methods of fixing tags to bales that has been a source of frustration and productivity loss is when the hanging tag becomes turned around in storage or transit. Bold human-readable numbers together with electronically 2 readable bar codes are printed onto one side of the identification tag. The current methods of attachment have required a single hole in the tag. Therefore the tag is able to twist around if exposed to wind or being knocked in transit, leaving the identifying numbers facing inwards and therefore not visible. Object of the Invention [0006] It is the object of the present invention to overcome or substantially ameliorate at least one of the above disadvantages. Summary of the Invention [0007] The present invention provides an attachment device integrally formed from a single piece of elastically flexible wire, said attachment device comprising: a first arm having a first arm proximal end and a first arm distal end defined by a first end of said wire; a second arm having a second arm proximal end and a second arm distal end; a head extending from said second arm distal end to a second end on said wire and defining a locking recess for captively retaining said first arm, towards said first arm distal end, in a closed position; and a spring extending between said first arm proximal end and said second arm proximal end and biasing said first arm to an open position in which said first arm is inclined at an acute angle to said second arm and spaced from said head. [0008] In one form, said head comprises a first head section extending from said second arm distal end and a second head section extending from said first head section, said first head section being inclined with respect to said second head section to define an opening therebetween for passage of said first arm therethrough and into said locking recess. [0009] In one form, said locking recess is formed by said second head section and is defined by a free end portion extending to said second end of said wire and defining a side of said locking recess, a base portion extending from said end portion and forming a base of said locking recess and a further portion extending from said base portion towards said first head section and defining an opposing side of said locking recess wherein, when 3 in said closed position, said first arm is positioned with said end portion and said further portion located on opposing sides of said first arm. [0010] In one form, said end portion extends at least substantially fully across said opening to said first section, such that urging of said first arm through said opening toward said second arm elastically displaces said end portion to allow said first arm to pass beyond said end portion with subsequent release of said first arm resulting in said first arm being guided into said closed position in said locking recess by said end portion under biasing action of said spring. [0011] Typically, said first head section is in the general form of a loop. [0012] The loop may be generally rectangular in form, being composed of four substantially linear lengths of said wire with a bend in said wire between each respective pair of adjacent said lengths. [0013] In one form, said spring comprises a single reflex angle bend in said wire. [0014] In a preferred embodiment, said wire is formed of spring steel. Brief Description of the Drawings [0015] A preferred embodiment of the present invention will now be described, by way of an example only, with reference to the accompanying drawings wherein: Figure 1 is a perspective view of an attachment device in an open state; Figure 2 is a front elevation view of the attachment device of Figure 1; Figure 3 is a bottom plan view of the attachment device of Figure 1; Figure 4 is a right hand elevation view of the attachment device of Figure 1; Figure 5 is a partially cross-sectioned fragmentary view of the attachment device of Figure 1 - partially cross-sectioned at section 5-5 of Figure 2; Figure 6 is a front perspective view of the attachment device of Figure 1 in a closed state; Figure 7 is a rear perspective view of the attachment device of Figure 1 in a closed state.
4 Detailed Description of the Preferred Embodiments [0016] Referring to the accompanying drawings, an attachment device 1 is integrally formed from a single piece of elastically flexible wire, formed into the attachment device 1 through a series of bends formed in the wire. The attachment device 1 is typically formed from spring steel wire having a diameter of approximately 1.0 mm, although other elastically flexible materials and sizes are also envisaged. [0017] The attachment device has a first arm 2 having a first arm proximal end 2a and a first arm distal end 2b. The first arm distal end 2b is defined by a first end of the wire from which the attachment device 1 is formed. Further along the piece of wire is formed a second arm 3 having a second arm proximal end 3a and second arm distal end 3b. A spring 4 extends between the first arm proximal end 2a and second arm proximal end 3a, biasing the first arm 2 to an open position relative to the second arm 3 as depicted in Figures 1 through 5. In the open position, the first arm 2 is inclined at an acute angle to the second arm 3. In the particular arrangement depicted, the first arm 2 is inclined at about 350 to the second arm 3 and the first and second arms 2, 3 lie in a common plane. The spring 4 is formed by a single bend of the single piece of wire through a reflex angle, here of approximately 3250. It is envisaged, however, that the spring 4 may be in the form of a twist in the wire through more than a full revolution, for example, through 685' (i.e., two full revolutions less 350) to provide a similar configuration to that in the arrangement depicted. [0018] A head 5 extends from the second arm distal end 3b and defines a locking recess 6 for captively retaining the first arm 2 toward the first arm distal end 2b in a closed position as depicted in Figures 6 and 7. It can be seen that, when the first arm 2 is in the closed position, a closed loop is defined by the first arm 2, second arm 3, spring 4 and head 5 so as to securely attach any two bodies threaded onto the first and second arms 2, 3. The head 5 is arranged such that, when the first arm 2 is in the open position, it is spaced from the head 5. [0019] In the particular form depicted, the head 5 comprises a first head section 7 extending from the second arm distal end 3b and a second head section 8 extending from the first head section 7 to a second end of the wire from which the attachment device 1 is formed. As best seen in Figure 4, the first head section 7 is inclined with respect to the 5 second head section 8 so as to define a tapered opening 9 therebetween that converges towards the second arm 3. As can again best be seen in Figure 4, the first arm 2 lies in a plane extending through the opening 9. The opening 9 provides a passage for the first arm 2 into the locking recess 6 that is here formed by the second head section 8. [0020] Specifically, the locking recess 6 is defined by a free end portion 10 of the second head section that extends to the second end of the wire forming the attachment device 1. The free end portion 10 defines one side of the locking recess 6. A base of the locking recess 6 is defined by a base portion 11 that extends from the end portion 10. Here the end portion 10 is inclined with respect to the base portion 11 by approximately 900 with a right-angle bend 12 formed in the second head section 8 between the end portion 10 and the base portion 11. An opposing side of the locking recess 6 is defined by a further portion 13 of the second head section 8. The further portion 13 is inclined with respect to the base portion 11 by approximately 90', with a further right-angle bend 14 being defined between the base portion 11 and the further portion 13. [0021] As best seen in Figures 6 and 7, when the first arm is in the closed position retained within the locking recess 6, the end portion 10 and further portion 13 are located on opposing sides of the first arm 2. The biasing action of the spring 4 biases the first arm 2 towards the base portion 11, so as to captively retain the first arm 2 within the locking recess 6. [0022] The end portion 10 of the second head section 8 is inclined with respect to the plane in which the base portion 11 and further portion 13 lie such that it extends at least substantially fully across the opening 9, as best depicted in Figure 5. This effectively closes off free passage between the opening 9 and the locking recess 6. In operation, however, urging of the first arm 2 through the opening 9 towards the second arm 3 results in the first arm 2 engaging the end portion 10, elastically displacing the end portion 10 to allow the first arm 2 to pass beyond the end portion 10. Once the first arm 2 has been urged beyond the end portion 10, releasing the first arm 2 results in the first arm 2 being guided into the closed position in the locking recess 6 by the end portion 10, under the biasing action of the spring 4. In other words, urging the first arm 2 against the side of the end portion 10 facing the opening 9 results in the end portion 10 being urged away from the first head section 7, allowing the first arm 2 to pass between the end portion 10 and the first head section 7 towards the second arm 3. When the urging pressure applied 6 to the first arm 2, which would typically be applied manually by a user, is released the biasing force of the spring 4 urges the first arm 2 away from the second arm 3 and into contact with the opposing side of the end portion 10, guiding the first arm 2 into the locking recess 6 towards the base portion 11 of the second head section 8. In the closed position, the first arm 2 may engage the base portion 11, although frictional forces acting between the first arm 2 and both the end portion 10 and further portion 13 will typically be sufficient to balance against the biasing action of the spring 4 and restrict movement of the first arm 2 towards the base portion 11. The first arm 2 should generally be sufficiently long such that it extends beyond the head 5 even when subject to deformation in typical use. [0023] The first head portion 7 is herein the form of a loop, which may be generally rectangular in form, comprised of four substantially linear lengths 15, 16, 17, 18 of the wire with a bend 19, 20, 21 being formed in the wire between each respective pair of adjacent lengths. The linear length 17 is positioned such that it touches the tip of the free end portion 10, thereby reducing any risk of tangling of cotton on the head 5 between the linear length 17 and the free end portion 10. A short transition portion 22 extends at right-angles from the length 18 of the first head section 7 to join the further portion 13 of the second head section 8. The rectangular form of the loop may be an elongate rectangular form but also encompasses a square form. It is also envisaged that the loop may be in any other form as desired, including circular or elliptical loop form. [0024] To secure a tag to a cotton bale or any other suitable substrate, the attachment device may first be pre-attached to the tag by threading the first arm 2 through a pair of spaced punched or slotted openings formed in the tag and then further advancing the attachment device 1 through the openings in the tag such that they are both positioned along the second arm 3. This may be achieved manually or automatically by machine. The head 5 and bend 4 at opposing ends of the second arm 3 then prevent the attachment device 1 form readily falling from the tag prior to attachment to the cotton bale. To attach the tag to the cotton bale, the woven fabric forming the casing of the cotton bale is then punctured with the sharp first arm distal end 2b. The first arm 2 is then pushed along behind the fabric casing, repuncturing the fabric casing to expose the first arm distal end 2a. The first and second arms 2, 3 are then grasped by the user and the first arm 2 urged in to the opening 9, past the end portion 10 of the second head section 8 and subsequently released so as to be captively retained in the locking recess 6. The attachment device 1 7 and tag are thus securely held together in place on the cotton bale, greatly reducing the risk of contaminating the cotton fibre. Feeding the attachment device 1 through two openings provided on the tag also resists the tendency of the tag to turn around when attached to the bale, thus allowing identification data on the tag to remain visible, eliminating the need for an operator to leave a vehicle in order to turn the tag around. [0025] For cotton bale applications, the attachment device 1 may have a length between the second arm proximal end 3a and second arm distal end 3b of about 70 mm, although the size of the attachment device 1 may be varied as desired to suit the intended application.