Elongated-member-driving apparatus – With interlock means
Reexamination Certificate
1999-09-17
2001-07-31
Smith, Scott A. (Department: 3721)
Elongated-member-driving apparatus
With interlock means
C227S119000, C227S120000, C227S136000
Reexamination Certificate
active
06267284
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to power actuated tools for driving fasteners into a substrate and particularly to such tools which operate by detonation of an explosive charge. More particularly the invention relates to power actuated tools in which the fastener such as a nail or pin is fed from a magazine into the tool. The invention also relates to a fastener such as carrier strip for use in such a tool.
2. Description of the Prior Art
Power actuated tools for driving fasteners such as nails or pins into a substrate such as a concrete or steel beam conventionally comprise a barrel from which the fastener is expelled by means of a piston driven by detonation of an explosive charge. Previously proposed tools of this type are described for example in our International patent applications Nos. PCT/AU98/00255 and PCT/AU90/00018 the disclosure of which is hereby incorporated by reference. Tools of the type described in our aforesaid applications are principally designed for use with a single fastener which is loaded manually into the front of the barrel for subsequent discharge when the forward end of the barrel is pressed against the surface to cock the tool to permit firing of the explosive charge upon actuation.
There is now an increasing demand for explosively actuated tools in which the fasteners are loaded automatically or semi-automatically from a magazine. In certain previously proposed tools with magazine feed, the magazine is carried by the body of the tool at the forward end thereof and fasteners are mounted seriatim on successive segments of a carrier strip housed within the magazine. The endmost fastener on the carrier strip is located within an axially displaceable fastener guide which forms an extension of the barrel of the tool, with the tool being cocked for subsequent firing when the forward end of the fastener guide is pressed against the substrate and displaced rearwardly relative to the body of the tool. A practical difficulty with a magazine fed tool is that an operator might not always be aware the supply of fasteners from the magazine has been used and accordingly may be unaware that there is no fastener loaded within the fastener guide. If the tool is fired under these circumstances, the driving piston will be under full power when it strikes an appropriate stop at the forward end of the barrel and which is likely to result in damage to the piston, the barrel, and possibly associated components.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, there is provided a power actuated tool for driving a fastener such as a pin or nail into a substrate, said tool comprising a body, a fastener guide mounted at the forward end of the body, said fastener guide being displaceable axially inwardly relative to the body when the forward end of the tool is pressed against a substrate whereby to permit firing of the tool, a magazine carried by the tool for containing a plurality of fasteners mounted seriatim on segments of a carrier strip, said magazine including means for advancing the leading end of the carrier strip and the fastener carried thereby into the fastener guide, and releasable locking means for impeding firing of the tool, said locking means being releasable in response to the presence of a fastener and associated segment of the carrier strip within the fastener guide whereby to permit firing of the tool only when a fastener is present within the fastener guide.
In a preferred embodiment of the invention, the locking means is operative to restrain the fastener guide against axial inwards movement relative to the body at least to an extent sufficient to permit firing of the tool.
Preferably the locking means is released by force exerted on the locking means by the force exerted on the carrier strip by the advancing means.
Advantageously, the locking means is released by force applied to the locking means via the carrier strip segment within the fastener guide.
In a preferred embodiment, the locking means comprises a locking member which is displaceable by engagement with the carrier strip segment within the fastener guide so as to permit inwards axial displacement of the fastener guide. Preferably, the locking member includes a cam which projects into the interior of the fastener guide so as to be engageable by the carrier strip segment within the guide to permit release of the locking member by an extent sufficient to enable some axial inwards movement of the fastener guide, the tool including means operative upon axial movement of the fastener guide with the locking means in its released position to effect further movement of the locking member sufficient to ensure that the cam is clear of the inner surface of the fastener guide so as to prevent contact with the head of the fastener and/or driving piston of the tool when the tool is fired.
A difficulty which may arise with a magazine-fed tool as described above concerns the proper location of the final fastener of the carrier strip within the fastener guide.
With the exception of the final fastener, each successive fastener fed into the fastener guide by the carrier strip will automatically be located in the correct position and orientation within the fastener guide due to the support provided by the following segments of the carrier strip still located within the magazine. However no such guidance will be provided for the final fastener and its associated segment of the carrier strip which will be completely removed from the magazine and within the fastener guide.
Therefore, according to another aspect of the invention, there is provided a carrier strip for use with a tool as defined above, said carrier strip comprising a plurality of carrier segments arranged seriatim, each carrier segment having means operable to retain a fastener so that the fasteners are retained within the carrier strip in parallel arrangement and each carrier segment including means arranged to co-operate with the locking means when that carrier segment is present within the fastener guide so as to cause release of the locking means, and the final carrier segment at the trailing end of the carrier strip including locating means for ensuring that the final segment when within the fastener guide is maintained in correct condition for co-operation with the locking means.
Preferably, the final carrier segment includes locating means co-operable with the advancing means of the magazine to locate the segment in a suitable position for correct co-operation with the locking means.
Preferably, the locating means is operative to maintain the final segment in a predetermined rotational position relative to the locking means and in a predetermined axial position relative to the locking means.
The present invention also provides a carrier strip as defined above carrying fasteners for use in the tool.
According to yet another aspect of the invention, there is provided a power actuated tool for driving a fastener such as a pin or nail into a substrate, said tool comprising a body, a fastener guide mounted at the forward end of the body, said fastener guide being displaceable axially inwardly relative to the body when the forward end of the tool is pressed against the substrate whereby to permit firing of the tool, a magazine carried by the tool for containing a plurality of fasteners mounted seriatim on segments of a carrier strip, said magazine including means for advancing the leading end of the carrier strip and the fastener carried thereby into the fastener guide, a cover movable from a closed to an open condition to permit loading of a fresh carrier strip with fasteners into the magazine, and means for providing an indication of the number of fasteners remaining in the tool, said indication being observable by an operator when the cover is in its closed condition.
In a preferred embodiment indication of the number of fasteners remaining is effected by viewing from outside of the tool with the cover closed, the position of the advancing means and/or the carrier strip
Knobbe Martens Olson & Bear LLP
Ramset Fasteners (Aust.) Pty. Limited
Smith Scott A.
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