This application claims priority to Great Britain Patent Application No. 0807390.0,filed 23 Apr. 2008, the entire content of which is hereby incorporated by reference.
The present invention relates to a method of joining together a first and second workpieces. In particular, the method comprises drilling a first hole at least partially through the first workpiece with a drill bit oriented in a first direction; drilling a second hole at least partially through the first workpiece with a drill bit oriented in a second direction which is not parallel with the first direction, the drill bit passing through the first workpiece into a side of the first hole; inserting a fastener through the second workpiece and into the first hole; inserting an anchor into the first hole via the second hole; and securing the fastener within the first hole with the anchor. The invention also relates to a drill guide for use in such a method.
A problem with such a method is how to align the drill bit correctly so that the drill bit enters the first hole at the correct position as it drills the second hole. One solution to this problem would be to provide a drill guide which is inserted into the first hole. However this may not be possible with the second workpiece in place.
A first aspect of the invention provides a method of aligning the drill bit during the drilling of the second hole. The method comprises placing a target magnet in the first hole without completely filling it; placing a drill guide with a guide magnet or magnetic field sensor next to the first workpiece; adjusting the position of the drill guide until the guide magnet or magnetic field sensor indicates that the drill guide is aligned with the target magnet; and drilling the second hole by passing the drill bit through the drill guide and at least partially through the first workpiece, the drill bit entering the side of the first hole at a location where the first hole is not filled by the target magnet.
The drill guide may comprise a guide magnet or a magnetic field sensor such as a Hall-effect sensor. Where a magnetic field sensor is used, then the sensor gives an output reading which indicates the strength of the magnetic field and hence reaches a maximum when the drill guide is aligned as required. Where a guide magnet is used, then the magnet will experience an attractive force which reaches a maximum when the drill guide is aligned, and thus provides an indication that the drill guide is aligned. In this case the drill guide may be “self-aligning” in the sense that the attractive force tends to move the drill guide towards the aligned position. Alternatively, if frictional forces between the drill guide and the first workpiece prevent such “self-aligning” operation then the drill guide may be adjusted into position manually, with the attractive force giving a tactile indication to an operator when the drill guide is aligned.
In the case where a guide magnet is used, then this may comprise a permanently magnetised magnetic material such as Neodynium Iron Boron, or an electromagnet. An electromagnet may be used where a high field strength is required, but is generally less preferred due to the requirement of wires to power the magnet.
Similarly, the target magnet may comprise an electromagnet but more preferably it comprises a permanently magnetised magnetic material such as Neodynium Iron Boron.
Typically the target magnet and/or the guide magnet is oriented with its north-south axis substantially parallel with the first direction.
The coupling between the anchor and the fastener may take a number of different forms. For instance the anchor may have a threaded hole into which the fastener is screwed to secure the fastener in place. Alternatively the fastener may comprise an anchor hole and the fastener is secured by inserting the anchor into the anchor hole.
The first hole and/or the second hole may be open at both ends, or may be blind holes open at one end only.
A second aspect of the invention provides a drill guide comprising a guide magnet with a north-south axis oriented in a first direction; and a guide hole oriented in a second direction which is not parallel with the first direction. Such a drill guide is particularly suited for use in the method of the first aspect of the invention.
Embodiments of the invention will now be described with reference to the accompanying drawings, in which:
First, a drill bit 16 shown in
In the next step shown in
The target magnet 10 comprises a Neodynium Iron Boron magnet which is permanently magnetised and glued onto the shaft of the target pin with its north-south axis pointing vertically down as shown, or in the opposite direction.
Next, as shown in
Next, a horizontal hole 17 shown in
Next, as shown in
Next, as shown in
Finally, as shown in
The use of the drill guide 11 and target magnet 10 enables the hole 17 to be correctly aligned and drilled without having to remove the skin 7 from the position shown in
Although the invention has been described above with reference to one or more preferred embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.
Number | Date | Country | Kind |
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0807390.0 | Apr 2008 | GB | national |
Number | Name | Date | Kind |
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5415502 | Dahlin | May 1995 | A |
5707375 | Durham et al. | Jan 1998 | A |
7003860 | Bloch et al. | Feb 2006 | B2 |
Number | Date | Country |
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672036 | May 1952 | GB |
1-121113 | May 1989 | JP |
Number | Date | Country | |
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20090269132 A1 | Oct 2009 | US |