Patent Publication Number: US-2022221610-A1

Title: Metal Detector

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Australian Provisional Patent Application No. 2021900058 filed Jan. 12, 2021, the disclosure of which is hereby incorporated by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present disclosure relates to a metal detector. 
     Description of Related Art 
     Hand-held metal detectors usually require a shaft that can support one or more control modules, a handle that can support a display module on top and an adjustable armrest. Further down the shaft a twist or cam lock is often fitted that allows a second shaft member to adjust the position of a search head to keep it close to the ground depending on the user&#39;s height and preferences. 
     It is advantageous to have the lightest detector possible to help the user detect for longer time periods without fatigue or tiring. However, given that metal detecting is nearly always outdoors, in usually remote harsh environments, the detector needs to be reliable and dependable. Hence the construction needs to be robust in order to withstand many knocks, and the various connected components need to remain firmly connected to the shaft so as not to have small counter movements that can disturb the user, who is nearly always fully concentrating to hear faint audio signals from the detector. 
     Traditional screw fastening arrangements onto round shafts can slip with time since the tightness of the clamping results in a friction grip. Initial friction grip may be in the order of 9-11 Nm, and while this is sufficient for the initial life of the detector, this friction grip falls off due to plastic creep over time to the point that the connecting structures slip with each swing of the detector sufficiently enough to become noticeable by the user. Users will then retighten the fasteners to re-establish the grip, sometimes over tightening, fracturing an already weak structure. While some solutions may employ anti-slip features such as apertures in the shaft to receive the fastener, these nearly always result in some amount of clearance between the fastener and aperture, resulting in undesirable movement between the shaft and the connecting structure. Furthermore, anti-slip features can be damaged and worn away through repeated usage making their application limited. Making these features stronger and more wear resistant always results in materials that increase weight. Another method to prevent rotation between the connecting structure and the shaft is to employ square or non-circular shafts, however said shafts are less volume efficient and nearly always result in a weight increase over a circular shaft for the equivalent strength and robustness. Hence, the need to find methods to use round shafts is a priority, as these are the most mechanically efficient and economic. 
     It is against this background that the present disclosure has been developed. 
     SUMMARY OF THE INVENTION 
     According to a first aspect, there is provided a body of a hand-held metal detector, comprising an elongated body with a first and second end, and a first connecting structure moulded directly onto the elongated body at the first end through an injection moulding process, wherein the connecting structure comprises an engaging portion configured to engage at least one attachment of the hand-held metal detector, such that the at least one attachment is supported by the elongated body through the connecting structure moulded directly onto the elongated body. 
     In one form, the engaging portion of the first connecting structure comprises at least one rail adapted to allow engagement of the attachment along the length of the rail. 
     In one form, the engaging portion of the first connecting structure comprises a pair of rails adapted to allow engagement of the attachment along the length of the rails. 
     In one form, the rails further comprise teeth, grooves or holes to facilitate locking of the attachment at specific locations along the length of the rails. 
     In one form, the first connecting structure comprises a second engaging portion configured to engage another attachment of the hand-held metal detector, such that the further attachment is supported by the elongated body through the connecting structure moulded directly onto the elongated body. 
     In one form, the body further comprises a second connecting structure moulded directly onto the elongate body at a location intermediate the first and second ends, wherein the second connecting structure comprises a third engaging portion configured to engage a handle or a grip, such that the handle or grip is supported by the elongated body through the second connecting structure moulded directly onto the elongated body. 
     In one form, the elongated body is a tubular shaft. 
     In one form, the tubular shaft is made from a fibre reinforced composite. 
     In one form, the tubular shaft is made from an aluminium alloy. 
     In one form, one or all of the connecting structures are made from a thermoplastic polymer. 
     In one form, the thermoplastic polymer is reinforced with minerals and/or fibres. 
     In one form, the elongated body comprises features to engage with the one or all of the connecting structures. 
     In one form, the features are holes, slots, knurling or grooves. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Embodiments of the present invention will be discussed with reference to the accompanying drawings wherein: 
         FIG. 1  is a side view of a body of a hand-held metal detector, according to an embodiment; 
         FIG. 2  is a top view of the body of a hand-held metal detector of  FIG. 1 ; 
         FIG. 3  is a front perspective view of the body of a hand-held metal detector of  FIG. 1 ; 
         FIG. 4  is a rear perspective view of the body of a hand-held metal detector of  FIG. 1 ; 
         FIG. 5  is a cross-sectional view of the body of a hand-held metal detector of  FIG. 1 ; 
         FIG. 6  is a front perspective view of the body of a hand-held metal detector of  FIG. 1  fitted with a variety of attachments; 
         FIG. 7  is a rear perspective view of the body of a hand-held metal detector of  FIG. 1  fitted with a variety of attachments; 
         FIG. 8  is a front perspective view of a body of a hand-held metal detector, according to a second embodiment; and 
         FIG. 9  is a side view of the body of a hand-held metal detector of  FIG. 8 . 
     
    
    
     DESCRIPTION OF THE INVENTION 
     Referring now to  FIGS. 1 to 7 , where there is shown a body of a hand-held metal detector  100 , according to an embodiment, comprising an elongated body  110  with a first and second end  111 ,  112  and a connecting structure  120  moulded directly onto the elongated body  110  at the first end  111  through an injection moulding process. The connecting structure  120  comprises an engaging portion  121  configured to engage at least one attachment of the hand-held metal detector  100 , such that the at least one attachment is supported by the elongated body  110  through the connecting structure  120  moulded directly onto the elongated body  110  at the first end  111 . 
     As best shown in  FIG. 3 , the engaging portion  121  of the connecting structure  120  comprises a pair of parallel rails  122  adapted to allow engagement of the attachment along the length of the rails  122 . The engaging portion  121  also features a plurality of teeth  123  which facilitate locking of the attachment at specific locations along the length of the rails  122 . As best shown in  FIGS. 6 and 7 , where the body  100  is shown fitted with a variety of attachments, the attachment is an arm cuff  130  which is configured to be slidably retained by the rails  122  and features a locking mechanism  131  that is able to selectively engage with the teeth  123  at any point along the rails  122 . 
     While in the embodiment shown, the connecting structure  120  comprises a pair of rails  122  to which the arm cuff  130  is engaged, it will be appreciated that a single rail and alternative locking arrangements (such as grooves or holes) are also considered to fall within the scope of this disclosure. 
     As best shown in  FIG. 4 , the connecting structure  120  further comprises a second engaging portion  124  configured to engage another attachment of the hand-held metal detector  100 , such that the further attachment is also supported by the elongated body  110  through the connecting structure  120  moulded directly onto the elongated body  110 . In this instance, the second engaging portion  124  comprises a tab  125  and a pair of locating pins  126  with which the further attachment  140  (a control module and battery pack) is slidably engaged and retained (as best shown in  FIGS. 6 and 7 ). 
     Again, it will be appreciated that alternative engaging portion arrangements are also considered to fall within the scope of this disclosure. For example, in an alternate embodiment, the second engaging portion  124  may comprise features such as grooves or keyways, configured to facilitate at least a portion of the attachment being over-moulded directly on to at least a portion of the connecting structure  120 . 
     The body  100  further comprises a second connecting structure  150  moulded directly onto the elongated body  110  at a location intermediate the first and second ends  111 ,  112 . The second connecting structure  150  comprises a third engaging portion  151  configured to engage a handle or grip  160  (as shown in  FIGS. 6 and 7 ) such that the handle or grip  160  is supported by the elongated body  110  through the second connecting structure  150  moulded directly onto the elongated body  110 . 
     It can be seen that the third engaging portion  151  comprises a plurality of apertures  152  through which fasteners (not shown) are used to secure the handle or grip  160  to the second connecting structure  150 . In alternate embodiments, fewer or more fasteners  152  may be used, and may be used in combination with other securing means such as clamps or dovetails. 
     Alternative means for securing the handle or grip  160  to the second connecting structure  150  may also include a pivot and clamp arrangement that allows the handle or grip  160  to pivot with respect to the shaft  110 , for stowage and/or to suit ergonomic preferences of the user. A further embodiment may provide toothed rails similar to those provided on the first connecting structure  120 , allowing the user to position the handle or grip  160  at a location they prefer. In yet a further embodiment, the third engaging portion  151  may comprise features such as grooves or keyways, configured to facilitate the handle or grip  160  being over-moulded directly on to at least a portion of the connecting structure  150 . 
     Referring now to  FIGS. 8 and 9  where there is shown a body of a hand-held metal detector  200 , according to a second embodiment, featuring the same first connecting structure  220  but an alternate second, intermediate structure  250 , wherein an entire handle or grip has been moulded directly onto the elongated body  210  through an injection moulding process. 
     In both embodiments, the elongated body  110 ,  210  is a tubular shaft, which may be made from a lightweight material, ideally with a high specific strength such as a carbon fibre reinforced polymer. Other suitable materials may include titanium or aluminium alloys. While the tubular shaft has a circular cross-section, it will be appreciated that alternative cross-sections would also be considered to fall within the scope of this disclosure. 
     In both embodiments, the connecting structures  120 ,  150 ,  220 ,  250  are made from a thermoplastic polymer which may be reinforced with various minerals and/or fibres. In a preferred form, the connecting structures  120 ,  150 ,  220 ,  250  are made from various types of Polyamides (such as Nylon 6, 66, 12, 10, 6/12, 6/10, etc), however, it will be appreciated that alternative thermoplastic polymers, such as ABS, Polycarbonate, Polypropylene and Polyesters and reinforcing materials such as glass, minerals, talc and carbon may also be employed. 
     The general qualities of the thermoplastics employed are that they are rigid with a Shore D hardness typically above 45. It will be appreciated that the thermoplastics employed need to maintain their rigidity and resistance to creep over a wide range of temperatures typically achieved in metal detecting regions around the world. 
     The connecting structures  120 ,  150 ,  220 ,  250  are injection moulded over the tubular shaft  110 ,  210 , such that they shrink during cooling and form a tight bond with the shaft  110 ,  210 . As shown in  FIG. 5 , the tubular shaft  110  may be provided with apertures  113  through which an amount of the connecting structure  120 ,  150  polymer flows during the injection moulding process and forms projections  127 ,  153  within each aperture  113 . During the injection moulding process, a mandrel is inserted within the shaft  110  to prevent the polymer flowing into the shaft  110 , thus allowing a second shaft (not shown) to telescope within the shaft  110 . The polymer fills each aperture  113  completely, eliminating any clearances that can initiate wear or micro movement. It will be appreciated that in addition to the tight bond formed by each of the connecting structures  120 ,  150  shrinking over the shaft  110 , that the relationship between the projections  127 ,  153  and the apertures  113 , further acts to prevent, or reduce, rotation or translation of the connecting structures  120 ,  150  with respect to the shaft  110 . It will be appreciated that this resistance to rotation and translation is achieved in a different manner to traditional securing methods which rely upon a tight clamping force which can work loose over time. 
     While in the embodiment shown, the shaft  110  is provided with apertures  113 , it will be appreciated that alternative means to engage with the connecting structures,  120 ,  150  may include slots, grooves or even knurling formed in or on the shaft  110 . 
     The first connecting structure  120  also features bands  128  that wrap around the shaft  110  rather than having a solid body that completely encloses the shaft  110 . It will be appreciated that this material reduction has weight saving benefits, while still achieving a satisfactory engagement with the shaft  110 . Further material reduction is also achieved by providing slotted holes in the rails  122 . 
     It will be appreciated that the above disclosure provides a light weight, yet robust body for a hand-held metal detector, capable of withstanding environmental and physical stresses exerted on it. By virtue of the connecting structures being moulded directly onto the shaft, the connected components, such as grips, arm cuffs, control modules and batteries are firmly connected to the shaft so as not to have small counter movements that can disturb the user. Furthermore, the direct moulding provides a fastenerless solution, which is not susceptible to vibration, loosening, creep or cracking over time, and also improves the overall assembly process by requiring fewer parts, faster assembly and not requiring a jig to correctly align components. 
     By not requiring fasteners to secure the connecting structures to the shaft, wall sections of the connecting structures are able to be reduced and reinforcing fibre content is also able to be reduced (since they do not need strength for traditional fastener attachment or clamping methods). The shafts themselves can also be thin walled as they do not need to support local stresses from torqued up fasteners clamping hard on the shaft. It will also be appreciated that the connecting structures supplement the strength of the shaft locally, hence in alternate embodiments, variable wall section shafts may be employed to reduce wall section where the connecting structure is supporting the shaft. 
     It will be appreciated that direct moulding also eliminates the need for gluing processes, which require time consuming and costly clean up, fume cupboards and precision dispensing as well as surface preparation to facilitate bonding. It will also be appreciated that a wider range of thermoplastics can be employed which have traditionally been excluded from traditional methods because of their low surface energy and difficulties in bonding. 
     Throughout the specification and the claims that follow, unless the context requires otherwise, the words “comprise” and “include” and variations such as “comprising” and “including” will be understood to imply the inclusion of a stated integer or group of integers, but not the exclusion of any other integer or group of integers. 
     The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement of any form of suggestion that such prior art forms part of the common general knowledge. 
     It will be appreciated by those skilled in the art that the invention is not restricted in its use to the particular application described. Neither is the present invention restricted in its preferred embodiment with regard to the particular elements and/or features described or depicted herein. It will be appreciated that the invention is not limited to the embodiment or embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope of the invention as set forth and defined by the following claims.