Patent Application
20110226834
The present invention relates to a tool for applying fasteners to a substrate to fix insulation thereto.
Insulation (thermal or acoustic) for use in building construction can be applied to an underlying substrate in a variety of ways determined by such factors as the particular usage, the type of insulation, and the type of substrate. Current practice in commercial building construction is for insulation batts or panels to be applied to a hard substrate such as a concrete wall panel or at the underside of a floor slab by means of purpose-designed fasteners using a powder actuated (p.a.) tool to drive a pin of the fastener into the hard substrate. The insulation is of various types and densities, including polystyrene (expanded and extruded), polyester, fibreglass, and mineral wool. P.a. tools use the power of an explosive charge which is sufficient to drive a fastener pin into a hard substrate such as a concrete structure or a steel beam. Current fasteners for applying insulation using a p.a. tool incorporate a fastener pin which is of a size to withstand the high forces generated by conventional p.a. tools. This compromises the overall design of the fastener and in practice it can be quite difficult to push the fastener body through batts of medium and hard density prior to firing the tool in order to drive the fastener pin into the substrate to retain the fastener thereto. Moreover, the use of the p.a. tool itself in this fastening situation gives rise to operational difficulties. P.a. tools are subject to quite substantial recoil on firing and particularly in a situation when an operator is working from below when fixing batts to the underside of a ceiling, it can be very tiring for the operator to absorb the recoil.
In practice, the body of the fastener is mounted on a fastener guide at the forward end of the tool and the tool is used to push the fastener body through the insulation until its end engages the substrate at which point the tool is fired to drive the fastener pin into the substrate. A safety mechanism built into p.a. tools requires the tool to be cocked prior to firing by pushing the forward end of the fastener guide against the component into which the fastener pin is to be fired whereby the fastener guide retracts into the body of the tool against a strong spring bias; firing cannot take place until that action has occurred. However in a situation where the tool is used to force the fastener body through the insulation using manual pressure applied by the operator, depending on the structure of the insulation itself, this may generate sufficient resistance as to cause a loading sufficient to displace the fastener guide rearwardly and thereby cock the tool ready for firing before the fastener body has been pushed fully through the insulation and into engagement with the underlying substrate.
In our co-pending application entitled “Fastener for insulation”, there is proposed an insulation fastener designed for use with tools for driving a fastening pin of smaller size, such as gas or air tools or p.a. tools modified for that purpose. Gas and air tools operate on a similar principle to p.a. tools by powering a driving piston along a barrel and fastener guide to engage a pin type fastener at the end of the guide. In a p.a. tool the piston is driven by firing of an explosive charge, whereas in a gas powered tool the piston is driven by explosive combustion of a gas, for example propane and/or butane, and in an air powered tool, the piston is driven by rapid expansion of compressed air from a compressed air source. However, gas powered and air powered tools require a cocking action similar to that described above in connection with p.a. tools, but the cocking force (the force required for displacement of the fastener guide into the tool body) is generally less. As a consequence of the reduced cocking force, there will be an increased tendency for the tool to cock prematurely under the loading which can arise as the fastener is forced through the insulation.
Although with all forms of tool of the type discussed, p.a., gas, or air, premature cocking is undesirable as it does permit the tool to be fired prematurely which means that the pin might not drive into the substrate or at least not properly drive into the substrate, a particular problem can arise with gas powered tools in which cocking the tool also initiates a timed combustion cycle for the gas; if the tool is not then fired within a predetermined time, usually about two seconds, the tool will not actuate, unburnt gas will be discharged, and the tool will need to be reset for further operation.
The present invention relates to a fastener driving tool of the type discussed (p.a., gas, or air), having means to prevent cocking of the tool during the action of forcing the fastener body through the insulation.
According to the invention, there is provided a tool for driving a fastener pin into a substrate to secure a fastener body to the substrate for fixing insulation or other cladding, the tool being of the type comprising a fastener guide and a driving piston driven along the fastener guide by gas pressure to engage and drive the pin, the fastener guide being displaceable axially inwardly relative to the body of the tool in order to cock the tool for firing of the driving piston, wherein the tool comprises means for enabling the tool to push the fastener body through insulation or other cladding into engagement with the underlying substrate without putting the tool into a condition in which firing can occur, the tool being thereafter able to be put into a condition to permit firing to take place.
In one embodiment, the means for enabling the tool to push the fastener body through the insulation or other cladding without putting the tool into a condition in which firing can occur comprises a releasable lock for preventing cocking of the tool during that action.
In another embodiment, the tool is a gas tool having control circuitry operable to initiate the gas combustion process in response to inwards displacement of the fastener guide, the circuitry being inoperative to initiate the combustion process during a first relative inwards displacement of the fastener guide occurring while pushing the fastener body into engagement with the underlying substrate, the circuitry being then operative to initiate the combustion process in response to a second relative inwards displacement of the fastener guide.
Advantageously, the tool is operable to be put into a condition in which firing can occur following engagement of the fastener body with the underlying substrate, by releasing axial load applied by an operator to the tool body to push the fastener body through the insulation or other cladding and then re-applying the axial load to the tool body whereby to cause cocking of the tool.
Further according to the present invention there is provided a tool for driving a fastener pin into a substrate to secure a fastener body to the substrate for fixing insulation or other cladding, the tool being of the type comprising a fastener guide and a driving piston driven along the fastener guide by gas pressure to engage and drive the fastener, the fastener guide being displaceable axially inwardly relative to the body of the tool in order to cock the tool for firing of the driving piston, wherein the tool comprises means for locking the fastener guide against axial displacement relative to the tool body sufficient to prevent cocking to thereby permit the tool to push the fastener body through insulation or other cladding into engagement with the underlying substrate without cocking the tool, the lock being thereafter releasable to permit cocking to take place.
In one embodiment of the invention, release of the lock against axial displacement occurs in response to release of axial load applied by an operator to the tool to push the fastener through the insulation or other cladding whereby when axial load is next applied this will have the effect of cocking the tool. Alternatively, the lock against axial displacement can be released by rotation of the tool relative to the fastener guide by the operator after insertion of the fastener through the insulation or other cladding. In further alternatives, other operator-controlled mechanisms can be used to provide the selective locking/unlocking effect.
In particularly preferred embodiments, the fastener guide is associated with a cam system which causes selective locking and release in different angular positions. Advantageously the cam system comprises a rotatable cam body carried by the fastener guide and having cam tracks which co-operate with a fixed cam member whereby the cam is successively indexed to locking and release positions for the fastener guide in response to manual force applied to the tool body by the operator.
Advantageously, the selective locking system defined above can be incorporated into certain existing designs of tool by providing an attachment in the form of a replacement fastener guide and associated locking system mounted to the forward end of the tool body in place of an existing fastener guide. Existing designs of tool can be converted for use specifically for use with insulation fasteners with this improved functioning without the need to design and build special tools for this purpose.
An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings in which:
The fastener shown in
The fastener for thermal and/or acoustic insulation bans, panels, or cladding in accordance with the preferred embodiment of the invention comprises a body 2 formed in one piece from a moulded plastics, for example polypropylene. The body comprises at its outer end (the end adapted to lie adjacent to the exposed face of the insulation) a large area disc-like head 4 having a generally planar inner face to engage the exposed face of the insulation. A tubular stem 6 extends inwardly from the inner face of the head 4 and narrows at its inner end portion to a sharp point 8. The inner end portion of the stem 6 is configured internally to receive and retain a fastener pin 10 (shown in outline in
The fastener of the preferred embodiment is of design for use with a gas powered or air powered tool which operates by powering a driving piston along a barrel and associated fastener guide to drive a fastener pin at the end of the fastener guide. In a gas powered tool, the piston is driven by explosive combustion of a gas, for example propane and/or butane, and in an air powered tool, the piston is driven by rapid expansion of compressed air from a compressed air source. The fastener pin 10 in the fastener of the preferred embodiment is of a size sufficient to withstand the driving forces either in a gas powered or air powered tool. These forces are generally less than those generated in a conventional p.a. tool and tend to be more controllable, and therefore the pin 10 can be of reduced size/strength in relation to those employed in current insulation fasteners designed for use with p.a. tools. However the fastener may also be used with a p.a. tool modified for the purpose as will be described later.
It will be seen from
The external surface of the stem 6 is formed with an array of fins 14 which commence closely adjacent to the pointed end 8 and extend longitudinally along the length of the stem. The fins 14 progressively rise from zero height adjacent the pointed end 8 and over the main body of the stem 6 their radially outer edges lie on an imaginary cylindrical surface of constant diameter throughout the major part of their length (see
The main body of the stem may be of constant outer diameter beyond its pointed tip portion, but it is preferred that the main body is slightly concave in an intermediate zone between its tip portion and outer end portion and this concavity is clearly visible in
The length of the stem 6 corresponds to the thickness of the insulation so that when the stem has fully inserted through the insulation with its pointed tip 8 in engagement with the underlying substrate, its head 4 will be in firm contact with the outer face of the insulation. It will be understood from this that, in practice, insulation fasteners in accordance with the preferred embodiment will be produced in a range of sizes, with stems of different length corresponding to different standard thicknesses of insulation.
With the insulation fastener in position in the insulation with its stem having fully penetrated the insulation into engagement with the underlying substrate, the tool (to which the fastener is still attached) can be cocked by the operator applying further forwards pressure to displace the body of the tool relative to the fastener guide. After cocking the tool can be fired so that the pin 10 drives into the substrate so as to anchor the fastener. It is to be noted that during driving of the pin 10, its head will collapse the internal tubular spigot 12 and this will act as a shock absorbing function as firing takes place.
Although the fastener has been described in relation to the fastening of thermal and/or acoustic insulation to the underlying substrate, it can also be used for fastening other cladding, particularly in the nature of a cellular or expanded foam, which requires the fastener to penetrate through its thickness before driving the fastener pin into the substrate. It is also to be understood that the underlying substrate is not necessarily of a hard nature, such as concrete; the substrate could be of a softer material, wood for example as in a wooden wall frame.
Although it is envisaged that the insulation fastener will primarily be used with gas or air tools which are designed for use with smaller fastener pins than conventional p.a. tools, it is also possible that the fastener could be used with a p.a. tool modified to incorporate a reduced diameter fastener guide and driving piston to accommodate the smaller pins, with the output power being reduced by means of a power control and/or the use of an explosive charge of reduced power.
Having described an insulation fastener with which a tool in accordance with a preferred embodiment of the invention can be used for application of the fastener, the tool itself will now be described.
The basic construction of the tool itself irrespective of whether it is a p.a. tool, a gas tool or air tool is substantially conventional and will be well understood by those skilled in the art and therefore a detailed description is not required here. The differences over conventional tools reside in the incorporation of a fastener guide modified to incorporate a locking system to prevent cocking of the tool by displacement between the fastener guide and tool body during penetration of the stem of the fastener through the insulation batt. Advantageously the modification is achieved by way of an attachment mounted to the forward end of existing tools of this type so that existing designs of tool can be modified specifically for this particular usage. Essentially, the attachment provides a replacement fastener guide and associated locking system. Although the modification is such that it is more likely to be undertaken by the manufacturer or supplier of the tool, nevertheless the attachment could be provided as an accessory for incorporation by the user. However, the modification by use of the attachment does mean that a tool manufacturer does not need to build completely different tools for this purpose.
With initial reference to
In the version shown in
In other versions, the barrel itself may be mounted for axial displacement within the tool and subject to a forward spring bias, with cocking taking place by rearwards displacement of the barrel. In that case the forward end of the barrel will co-operate with the rear end of the fastener guide to provide the forward spring bias to the fastener guide.
The detailed structure of the cylindrical cam body 44 and its co-operation with the fixed housing 40 will now be described in detail with reference to the
The cylindrical cam body 44 has upper and lower peripheral cam tracks 50, 52 and axial cam tracks 54 extending from the upper cam track 50. The housing 40 carries a series of fixed cam pins 56 evenly spaced around its axis for co-operation with the cam tracks 50, 52, 54 in a manner to be described to provide an indexed, stepwise, rotation of the cam body. The co-operation between the cam pins and the cam tracks provides for controlled locking of the cam body 44 and thus of the fastener guide 42 against axial movement and for controlled release of such locking. The use of several cam pins 56 evenly distributed around the housing 40 ensures balanced operation of the cam body 44 but as the cam pins each co-operate with the adjacent portion of the cam tracks in the same way, the interaction between just one of the cam pins and its associated portion of the cam tracks will be described in the following.
When the next fastener has been applied to the end of the fastener guide 42 as previously described and its tubular stem is inserted into the insulation batt by manual force applied by the operator to the tool, if the force required for insertion/penetration exceeds the forward spring loading on the fastener guide, the fastener guide and cam body will displace axially inwardly. This inwards displacement causes a ramped section r1 on the upper cam track 50 to engage the cam pin whereby the cam body will be indexed angularly until the cam pin seats in an arcuate crest at the upper end of that ramped portion thereby limiting further rotation at this stage. This is the condition shown in
In order now to cock the tool in preparation for firing, the operator releases the forward pressure on the tool body. As the tool body draws rearwardly, the cam pin will engage the next ramped section r2 on the lower cam track 52 and will index the cam body until the cam pin rests in the adjacent arcuate valley associated with that segment of the lower track. This is shown in
An alternative embodiment (not shown) of somewhat simpler construction involves the use of a torsionally-biased twist locking mechanism which, in a normal condition, locks the fastener guide against axial movement relative to the housing 40 thereby preventing cocking of the tool during insertion and penetration of the insulation batt. To facilitate cocking when insertion has been completed, the tool body and thereby the housing is rotated through a predetermined angle relative to the fastener guide and this has the effect of releasing the lock between the fastener guide and housing so as to then permit the tool body to be pressed forwards (relative to the fastener guide) sufficiently to permit cocking. This effect can be achieved by means of a cam pin carried by a housing (similar to the housing 40) engaging in a simple cam track formed on the fastener guide, with a torsional bias being provided between the fastener guide and housing to ensure that the fastener guide will return angularly to its locked position after firing when the forward pressure on the tool body is released. This embodiment relies on the inserted fastener having sufficient torsional anchorage within the bat to ensure that the tool body is able to rotate relative to the fastener guide which is restrained against rotation by its attachment to the fastener itself. While sufficient torsional anchorage of the fastener may occur when it is used with relatively dense batts, this may not arise with foam batts of reduced density or batts made of glass wool. Accordingly while this embodiment does have utility, its utility is restricted principally to use with foam and other batts of relatively high density. While such batts will be used in many commercial situations, nevertheless the previous embodiment is preferred as it is suitable for use with all types of batts, irrespective of their density as the angular indexing system used in that embodiment does not rely on angular retention of the fastener guide for its operation.
The embodiments thus far described basically involve the use of an attachment which provide a replacement fastener guide and associated locking system so as to prevent cocking of the tool when pushing the fastener through insulation or other cladding. While the attachments are applicable to p.a. tools, gas tools, or air tools, in the case of a gas tool the required effect can alternatively be achieved through modifications to the control circuitry of the tool rather than through a mechanical locking system as occurs in the embodiments described thus far. In particular, in a typical gas tool cocking of the tool by retraction of the fastener guide into the body of the tool as previously described actuates a limit switch which, through appropriate control circuitry, initiates injection of fuel and operation of a fan to mix the fuel with air so as to permit firing of the tool by operation of the trigger. However by modifying the control circuitry, initiation of the combustion process in the manner described can be achieved at every alternate (second) actuation of the limit switch whereby on a first actuation which occurs when pushing the fastener through the cladding, cocking of the tool by initiation of the combustion process will not take place. In order to cock the tool in preparation for firing, the operator releases the forward pressure on the tool body and then reapplies the pressure sufficiently to cause a second actuation of the limit switch which will then result in initiation of the combustion process. In this version the control circuitry can be configured to permit, selectively, cocking of the tool at alternate actuations of the limit switch just described, or cocking at each actuation when regular operation of the tool is required.
It is envisaged that in other tools modifications to directly inhibit/disable the firing process could be made to achieve the required effect instead of mechanically locking the fastener guide as in the embodiments described in detail herein.
The embodiments have been described by way of example only and modifications are possible within the scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008906096 | Nov 2008 | AU | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/IB09/55321 | 11/24/2009 | WO | 00 | 5/12/2011 |
