AU662390B2 - Apparatus and composition for propelling an object - Google Patents

Description

f 662 AUSTRALIA 6 2 PATENTS ACT 1990 COMPLETE SPECIRCATION FOR A STANDARD PATENT F Ref: 233381 390

ORIGINAL

Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: Sencorp One Riverfront Place Newport Kentucky 41071 UNITED STATES OF AMERICA Brian K. Hamilton Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Apparatus and Composition for Propelling an Object

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The following statement is a full description best method of performing it known to me/us:of this invention, including the 5845/5 U 1 I -u -rnru

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APPARATUS AND COMPOSITION FOR PROPELLING AN OBJECT Technical Field of the Invention The present invention generally relates to propelling fastening elements and, more particularly, to propelling such fastening elements with a propellant charge, contained within a substantially non-rigid and preferably sealable carrier strip, which is ignited with a sensitizer whicl is also contained within the carrier strip.

Background of the Invention A wide variety of devices are available for driving fastening elements into a given surface in high production applications staple driving devices, nail driving devices) (hereinafter "nail driving devices"). Many of these nail driving devices are pneumatically operated and therefore typically require that the nail driving device be connected to an air compressor by a hose or other similar conduit. Although these pneumatically operated nail driving devices effectively perform the required function of propelling a fastening element, the hose connection limits and/or impairs the operaor's mobility. In order to eliminate these mobility problems, charge-operated nail driving devices have been developed which do not require any type of a separate external pow', source for providing the required propelling forces.

One type of charge-operated nail driving device utilizes caseless charges which are positioned within a magazine, either individually or in combination with spacers. In one configuration, the charges are directly 'i ignited in place as they are advanced in the magazine. As can be appreciated, this ignition method significantly increases the wear cf the magazine and as a result, often the magazine must be periodically replaced. In addressing.

this problem, subsequent designs incorporate mechanisms to transfer the charge from the magazine to a firing chamber for ignition. U.S. Patent Nos. 4,066,198 and 4,066,199 to Jochum et al., issued January 3, 1978, are generally representative of this type of charge-operated nail driving I0 device. In this type of configuration, the caseless charges are individually advanced into the required position from the magazine and are then directly ignited via the impact of a firing pin or another appropriate ignition mechanism to generate the force used to drive the fastening element from the nail driving device via combustion gases). This configuration therefore requires additional parts to move the charges into position near the i firing pin and to possibly extract the charges from this position after the charges have been ignited. As a result of these additional and sometimes complex mechanisms, manufacturing costs are increased.

U.S. Patent Nos. 4,063,672 to Jochum, issued December S 20, 1977; 4,138,788 to Jochum, issued February 13, 1979; S4,368,588 to Jochum et al., issued January 18, 1983; 4,406,079 to Buechel et al., issued September 27, 1983; 4,611,738 to Jochum, issued September 16, 1986; and 4,410,124 to Buechel, issued October 18, 1983, are generally representative of another type of charge-operated -2nail driving device which generally utilizes the positioning of caseless charges within a carrier strip. In operation, the carrier strip is advanced and an individual charge is positioned within or adjacent to a firing chamber.

where it is directly struck by a firing pin or another appropriate ignition mechanism to initiate ignition. When the charge is ignited, the forces generated by the ignition and subsequent burning of the charge are directed upon the fastening element, either directly or indirectly, to propel the fastening element from the nail driving device.

A number of alternative structures and/or compositions have been employed for "caseless" charges of the abovedescribed type. For instance, U.S. Patent No. 3,372,643 to Kvavle, issued March 12, 1968, discloses a primerless charge. Generally, a nitrocellulose charge having a nitrogen content nitration level) of 12 to 15% by weight is utilized. Moreover, the charge is configured such that there is a localized initial ignition area.

Consequently, the charge may be ignited by the frictional engagement of an impacting firing pin. However, it is believed that igniting a charge in this manner requires a substantial high energy impact by the firing pin.

Caseless charges have also incorporated a structure which utilizes a propellant charge and a primer, U.S.

Patent Nos. 3,911,825 to Gawlick et al., issued October 14, 1975, and 4,056,062 to Walser et al., issued November 1, 1977, being generally representative of this type of caseless charge. In these types of configurations, the

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:i i -LI~ primer is typically ignited by the impacting of a firing -pin thereon. More particularly, the reaction which initiates ignition occurs within the primer itself. The ignition of the primer is then used to ignite the.

propellant charge.

An alternative to the above-described "caseless" charges are those which use a substantially rigid cartridge to contain the charge as generally and representatively disclosed in U.S. Patent Nos. 3,625,153 to Gawlick, issued December 7, 1971; 3,923,226 to Maier, issued December 2, 1975; 4,560,061 to Haytayan, issued December 24, 1985; and 4,819,562 to Bo wman, issued April 11, 1989. The cartridges typically utilize a primer and a propellant, such as gun powder. Since these cartridges are typically formed from 15 metals, however, nail driving devices utilizing such cartr-idges become rather expensive to operate in the high production applications for which they were designed due to the high material costs for the cartridges. Moreover, the gun powders which are used in many of these types of devices generate toxic byproducts which is undesirable when the nail driving device is used in closed or restricted ventilation conditions.

U.S. Patent No. 3,529,548 to Gawlick, issued September 22, 1970, discloses a somewhat flexible cartridge structure. In one embodiment, the cartridge utilizes an annular propellant receiving chamber, which contains a propellant powder charge, and a central primer receiving chamber, which contins the primer charge. The top of the -I fi cartridge incorporates a firing pin such that when the cartridge is compressed, the firing pin engages and ignites the primer charge which in turn ignites the propellant powder charge. In order to reduce the potential for pre-ignition of the primer charge, the firing pin is maintained a certain distance from the primer charge by a tubular extension positioned on the bottom of the cartridge.

U.S. Patent No. 3,828,676 to Junker, issued August 13, 1974, discloses another type of compressible cartridge structure. Generally, the cartridge utilizes an outer jacket and an inner shell, the propellant being positioned between the outer jacket and the inner shell and the primer being contained within the inner shell. When the cartridge is lo0 sufficiently compressed, the primer detonates which in turn ignites the propellant.

Summary of the Invention According to a broad form of the invention there is provided an article for moving a member, comprising: a friction-stnsitive ignitable first composition means, comprising a porous and fibrous material, for propelling said member by combustion of said first composition means; and second composition means, physically distinct from said first composition means, for igniting said first composition means when movement of said member is desired, wherein an impacting of said second composition means causes said second composition means to frictionally engage said first composition means and ignite said first composition means; and external casing means for containing said first and second composition means within said casing means. The present invention generally includes a plurality of propellant charges, each having a separate sensitizer associated therewith, which are contained within a substantially non-rigid carrier strip for use in a fastening element driving apparatus. The carrier strip is advanceable so as to appropriately align a propellant charge and its associated sensitizer with the ignition assembly a firing pin). When activated by the operator the firing pin impacts the sensitizer which in turn, impacts the propellant charge.

S 30 The friction created by this frictional engagement between the 0* i [N:\libff]00226:LMM U

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[1 sensitizer and the propellant charge ignites the propellant charge to generate the gases used to drive the fastening element from the device. Since a multiplicity of the pairs of propellant charges and sensitizers may be positioned within the carrier strip, the fastening element driving apparatus may be used in high production applications.

The combustion of the propellant charge generates the gases which are used to propel the fastening element. In certain applications, such as when the fastening element driving apparatus is being used in locations having little or no ventilation, it is desirable for the combustion of the propellant charge to avoid introducing significant quantities of toxic byproducts which could be harmful to the operator. Consequently, in one embodiment of the present invention a composition of potassium chlorate (or effective chemical equivalents thereof alkali metals), as long as there is chlorate on the surface of such composition to react with the sensitizer described beliow) and fibrous nitrocellulose is used for the propellant charge since it reduces this toxicity problem.

This composition is also advantageous in that it is water resistant, as well as friction-sensitive such that a sensitizer and firing pin may be used for ignition of the propellant charge. Furthermore, the composition does not detonate it burns at a subsonic rate), which enhances operator safety. As can be appreciated, additional oxidizers may also be utilized in the composition, such as potassium perchlorate and potassium -6- L ~.11 li- i 1~ 1 I nitrate. In another embodiment, 1-nitroguanadine is added to the above composition to provide a propellant charge which offers increased force-generating capabilities and a reduction of combustion residue.

The sensitizer is mechanically activatable and thus may be impacted by a firing pin to ultimately ignite the propellant charge. More particularly, it is desirable for the interaction of the sensitizer and propellant charge to be friction sensitive as noted above, and thus in one embodiment the composition of the sensitizer includes red phosphorous and nitrocellulose. This composition also provides a safety feature in that it is non-detonatable.

As can be appreciated, varying quantities of red phosphorous and nitrocellulose may be utilized, including utilizing possibly no nitrocellulose. Moreover, it may be desirable to incorporate abrasives into the composition of the sensitizer.

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An assembly including a single propellant charge and sensitizer are contained and iolated within the substantially non-rigid carrjir strip. In one embodiment, the carrier strip includes cap strip having a cavity for Sreceiving the propellant charge. The propellant charge is sealed within this cavity by a seal strip which has the sensitizer attached thereto. The cap strip and seal strip are then joined by conventional methods to effectively isolate the propellant charge and the sensitizer. In order to reduce the potential for preignition of the propellant charge, in one embodiment the propellant charge and the -7i- sensitizer are maintained in a separated position by a standoff a circumferential rib), which is positioned t on the seal strip. The sensitizer may therefore be positioned within the interior of the circumferential ribof the standoff and be attached to the seal strip to maintain this desired separated orientation.

I In operation, the present invention is positioned within a fastening element driving apparatus having an appropriate mechanism for feeding the carrier strip, and preferably an appropriate mechanism for positioning the fastening elements to be propelled by the present invention. The carrier strip is advanced such that an individual propellant charge/sensitizer assembly is positioned in the area in which the propellant gases are to be directed. When activated by the operator, a firing pin or another appropriate mechanism impacts the sensitizer, which then drives the sensitizer into engagement with the propellant charge in a manner which generates sufficient friction to ignite the propellant charge. Combustion of the propellant charge thereafter generates the gases necessary to propel the fastening element in the desired manner. In order to increase the efficiency of the gases Sdirected toward the fastening element, in one ebdmn the carrier strip may be formed from a material which may be sealingly engaged by a portion of the fastening element apparatus.

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Brief Description of the Drawins Other features and advantages of the present invention will become apparent in view of the following description taken in connection with the attached drawings, wherein: Figure 1 illustrates a carrier strip containing a plurality of charge assemblies for propelling an object in accordance with one embodiment of the present invention; Figure 2 is a cross-sectional view of one of the charge assemblies of Figure i taken along line 2-2; and Figure 3 generally illustrates the carrier strip and charge assemblies of Figure 1 as they may be utilized by a fastening element driving apparatus.

Detailed Description The present invention will be described with reference to the attached drawings which illustrate the pertinent features thereof. Generally, the present invention is a charge assembly which is used to provide the forces required to propel fastening elements from a fastening element driving apparatus. Based in part upon the construction of the charge assembly, namely a first composition and a second composition which are substantially contained within a substantially nc>-rigid material, the present invention provides a number of advantages over existing devices.

One embodiment of the present invention is illustrated in Figures 1-2. A substantially non-rigid carrier strip contains a plurality of charge assemblies 38 which are used

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to propel an object such as a fastening element nail, staple, bolt) from a fastening element driving apparatus (not shown). Each charge assembly 38 includes a propellant charge 42 and a sensitizer 46. The primary function of the propellant charge 42 is to generate sufficient gases via combustion such that a fastening element may be propelled with sufficient force, whereas the sensitizer 46 is used to frictionally react with the propellant charge 42 to cause the ignition thereof.

Therefore, the carrier strip 10 may be advanced within the fastening element driving apparatus (not shown) so as to align a charge assembly 38 with, for instance, a firing chamber and an ignition mechanism, such as a firing pin, so as to direct the required forces on the fastening element at the required time.

The combustion of the propellant charge 42 is used to generate the propelling forces required for operation of a fastening element driving apparatus (not shown). Since these fastening element driving apparatuses are sometimes used in areas where there is little or no ventilation, there have been problems with previous charge-operated apparatus in that the combustion of the charge has produced toxic byproducts which is not only potentially harmful to the operator, but possibly results in non-compliance with OSHA standards. Consequently, one embodiment of the present invention utilizes a composition for the propellant charge 42 which reduces this toxicity problem, the primary components of which are potassium chlorate and U- nitrocellulose. As can be appreciated, oxidizers such as -potassium perchlorate and potassium nitrate may be also utilized in the composition. Moreover, effective chemical Sequivalents of potassium chlorate alkali metal.

chlorates), such as sodium chlorate, may be utilized as long as there is chlorate on the surface of the propellant charge 42 to react with the sensitizer 46 in a manner discussed below.

In the above-described composition of the propellant charge 42, approximately 40% to about 70% is potassium chlorate by weight and approximately 30% to 60% is nitrocellulose by weight, the preferred composition being about 55% potassium chlorate by weight and about fibrous nitrocellulose by weight. This composition offers a number of advantages. Initially and as discussed above, the combustion of this composition reduces the amount of toxic byproducts, primarily due to the oxygen balance i provided by this composition. This composition is also substantially non-toxic in its pre-ignition state as well.

Moreover, the nitrocellulose enhances the water resistance 'of the composition, whereas the chlorate enhances the frict on-sensitivity of the composition to thereby allow the propellant charge 42 to be ignited by the interaction with the sensitizer 46. FurtXlrmore, this composition is 25 non-detonatable the combustion rate is subsonic) which enhances operator safety. In this regard, preferably commercial 12% nitrogen grade nitrocellulose is utilized -11-

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since it enhances the desired non-detonatable quality of -the composition of the present invention.

In another embodiment, the propellant charge 42 includes a composition of nitrocellulose, potassiumchlorate, and l-nitroguanadine. The addition of the 1nitroguanadine to the above-described composition increases the force-generating capabilities of the combustion of the propellant charge 42 and it also reduces the amount of residue generated during combustion of the propellant charge 42. However, the l-nitroguanadine also results in a less fibrous propellant charge 42 which affects the manufacturing process discussed below. Although the particular composition of this embodiment may vary depending upon the desired qualities of the propellant charge 42, a composition of 55% l-nitroguanadine by weight and 45% potassium chlorate by weight, mixed with a composition of 55% potassium chlorate by weight and KI nitrocellulose by weight, in varying proportions, may be utilized.

Although the propellant charges 42 can be produced by Sa variety of ways from the described compositions, one method has proven to be particularly advantageous. In one S embodiment in which the propellant charge 42 is to be produced from the above-described quantities of potassium chlorate and nitrocellulose, the nitrocellulose fibers are placed into a solution of water and possibly a binder and/or acetone. The binder assists in the formation of the composition and the acetone is used to "soften" the fibrous -12-

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nature of the composition, namely the nitrocellulose. The components are then mixed into the form of a slurry which is rolled out onto a sheet and dried. Propellant charges 42 of the desired shape may then be cut out from the sheet.

In utilizing this process, a predictably porous structure for the propellant charge 42 is achieved which enhances the burn rate of the charge 42. Moreover, the process is reprodicible so that propellant charges 42 of similar quality can be produced on a relatively consistent basis.

As can be appreciated, the process is effectively analogous to paper-making technology.

The sensitizer 46 is used to ignite the propellant charge 42 by frictional engagement therewith. Since the present invention may be used with a fastening element driving apparatus which utilizes a mechanical firing mechanism such as a firing pin, it is desirable for the interaction of the sensitizer 46 and the propellant charge 42 to be friction-sensitive. Although the preferred composition of the sensitizer 46 utilizes about nitrocellulose by weight and about 95% red phosphorous by weight, it is possible that the nitrocellulose may comprise from 0%-90% of the composition of the sensitizer 46 and still provide a sufficient ignition of the propellant charge 42 by the described frictional engagement utilizing 100% red phosphorous and no nicrocellulose).

Moreover, it may be desirable to incorporate abrasives into the composition of the sensitizer 46.

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Based upon the foregoing, it can be appreciated that -a charge assembly 38 and its separate sensitizer 46 and propellant charge 42 ignites in a manner which is different than, for instance, a cartridge which utilizes a primer anda propellant. A primer is generally a primary explosive which itself detonates or ignites when impacted by a firing pin. More particularly, the initial reaction which results in ignition of the primer occurs within the primer itself.

In contrast, the frictional interaction between the sensitizer 46 and propellant 42 effectively results in the simultaneous ignition thereof. More particularly, the initiating reaction occurs at the interface between the sensitizer 46 and the propellant charge 42 as a result of the frictional engagement therebetween. Consequently, 15 ignition of the charge assembly 38 is due to the interaction between the two materials.

The combination of the propellant charge 42 and the sensitizer 46 which forms each charge assembly 38 is contained within the substantially non-rigid carrier strip 10. In one embodiment, the carrier strip 10 includes a cap strip 14 and a'seal strip 22, both of which are formed from a substantially non-rigid material. These materials are preferably flexible, sealable so that they may in effect function as a gasket as discussed below) and capable of effechively isolating individual charge assemblies 38.

Materials such as treated paper, polycarbonate, and cellulose acetate are therefore suitable for both the cap strip 14 and the seal strip 22.

-14- I A plurality of charge assemblies 38 may be positioned within the carrier strip 10, each charge assembly 38 being substantially isolated. Moreover, the carrier strip based upon the above-described qualities of the materials used to form the carrier strip 10, may be conveniently rolled up or flaked folded). Therefore, the carrier strip 10 and the plurality of charge assemblies 38 therein are a suitable driving force for a fastening element driving apparatus in high production applications.

The cap strip 14 and the seal strip 22 are joined by conventional methods such as heat sealing, using secondary adhesives, or dielectrical or ultrasonic welding to in effect isolate each charge assembly 38. In order to enhance the safety accorded to the operator using the present invention, the cap strip 14 and seal strip 22 may assume a particular configuration to reduce the potential for preignition of the propellant charge 42. In this regard, the cap strip 14 may have a cavity 18 formed therein for recaiving the propellant charge 42. Moreover, the seal strip 22 may have a standoff 26 formed thereon, the standoff 26 including a circumferential rib 30 to form a cavity 34 therebetween as best illustrated in Figure 2.

Consequently, the sensitizer 46 may be effectively "painted" on the seal strip 22 in this particular area.

Nonetheless, the circumferential rib 30 of the standoff 26 may engage the propellant charge 42 so as to separate such from the sensitizer 46 to reduce the potential for preignition.

.9 Figure 3 generally illustrates one embodiment of the present invention as it may be utilized in a fastening element driving apparatus. In this regard, the carrier strip 10 is appropriately positioned within a fastening° element driving apparatus (only portions generally shown) which will accommodate the use of the carrier strip Once again, due to the flexibility of the carrier strip it may be rolled up or flaked so as to not require a significant amount of additional space within the driving apparatus. The advance mechanism (not shown) then positions an unfired propellant charge 42 and sensitizer 46 in proximity to a firing chamber 50 by, for instance, pulling the carrier strip 10 up in the direction indicated by arrow A. A fastening element 58 and drive piston 60 are also generally illustrated as being within the firing chamber 50, the drive piston 60 being positioned between the charge assembly 38 and the fastening element 58.

Although a particular construction has been described for the fastening element driving apparatus, it can be appreciated that the propellant gases need only exert a force, directly or indirectly, on the fastening element 58.

Consequently, the fastening element 58 may assume a variety of positions, such as within a separate chamber which is in communication with the firing chamber 50, and a drive S 25 piston 60 need not necessarily be used. Therefore, the present invention may be used in fastening element driven apparatus of various constructions.

-16i One problem encountered with some existing caseless charge-operated fastening element driving apparatus is that it has been difficult to :hieve an effective seal of the caseless charge within the given firing chamber, therebyresulting in an inefficient use of the combustion gases.

One embodiment of the present invention provides features which reduces this problem. As previously discussed, the carrier strip 10 is formed from a substantially non-rigid material. Therefore, in the event the fastening element driving device has components which may seal against the carrier strip 10, the gases from the combustion of the propellant charge 42 can be more efficiently used. For instance, the driving apparatus may utilize a member 62 which may move both toward and away, in the direction indicated by arrow B, from an engaging surface 54 which is located in proximity to the firing chamber 50. Therefore, the member 62 may be initially positioned so as to allow the carrier strip 10 to be advanced between the member 62 and the engaging surface 54. When a charge assembly 38 is properly positioned near the firing chamber 50, the member 62 will advance toward the engaging surface 54 and fix the carrier strip 10 therebetween, the carrier strip 10 then being moved into engagement with the surface 54 in the direction indicated by arrow C. The compressed carrier strip 10 thereby effectively acts as a gasket to seal the firinq chamber 50. When the firing pin or other ignition mechanism passes through the hole 64 in the member 62 to impact the sensitizer 46, the gases generated by combustion -17-

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p.~ ii d ii .1 r of the propellant charge 42, again due to the frictional engagement between the sensitizer 46 and the propellant charge 42 as the sensitizer 46 impacts the propellant charge 42 ignition as a result of the interaction between the propellant charge 42 and the sensitizer 46), are appropriately directed toward the drive piston 60 which then propels the fastening element 58. After the propellant charge 42 has effectively propelled the fastening element 58, the member 62 retracts such that the carrier strip 10 may be advanced to position the next charge assembly 38 near the firing chamber 50 and the described firing process can therefore be repeated.

The foregoing description of the present invention has been presented for purposes of illustration and description. Further, the description is not intended to limit the present invention to the form disclosed herein.

Consequently, variations and modifications commensurate with the above teachings, in the skill or knowledge of the relevant art, are within the scope of the present invention. The embodiments described hereinabove are further intended to explain best modes known of practicing the invention to enable others skilled in the art to utilize the invention in such, or other, embodiments and with the various modifications required by their particular applications or uses of the present invention. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art.

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Claims (19)

1. An article for moving a member, comprising: a friction-sensitive ignitable first composition means, comprising a porous fibrous material, for propelling said member by combustion of said first composition means; and second composition means, physically distinct from said first composition means, for igniting said first composition means when movement of said member is desired, wherein an impacting of said second composition means causes said second composition means to frictionally engage said first composition means and ignite said first lo composition means; and external casing means for containing said first and second composition means within said casing means.

2. An article, as claimed in claim 1, wherein said first composition means comprises potassium chlorate and nitrocellulose.

3. An article, as claimed in claim 2, wherein said first composition means comprises from about 40% to about 70% potassium chlorate by weight and from about to about 60% nitrocellulose by weight.

4. An article, as claimed in claim 1, wherein said first composition means comprises about 55% potassium chlorate by weight and about 45% nitrocellulose by weight.

An article, as claimed in claim 1, wherein said first composition means J ;comprises potassium chlorate, nitrocellulose, and 1-nitroguanadine.

6. An article, as claimed in any one of claims 1 to 5, wherein said first composition means is substantially water resistant.

7. An article, as claimed in any one of claims 1 to 6, wherein said first composition means is suostantially non-toxic both prior to and after ignition.

8. An article, as claimed in any one of claims 1 to 7, wherein said first composition means is non-detonatable.

9. An article, as claimed in any one of claims 1 to 8, wherein said second l 30 composition means comprises phosphorous and nitrocellulose.

An article, as claimed in claim 9, wherein said second composition means comprises from about 92% to about 98% red phosphorous by weight and from about 2% to about 8% nitrocellulose by weight.

11. An article, as claimed in claim 1, wherein said second composition means comprises about 95 red phosphorous by weight and about 5 nitrocellulose by weight.

12. An article, as claimed in any one of claims 1 to 11, wherein said casing means further comprises an upper sealing material and a lower sealing material.

13. An article, as claimed in claim 12, wherein said upper sealing material has a cavity means for receiving said first composition means. [N:\libff]00226:LMM i: i

14. An article, as claimed in claim 12 or claim 13, wherein said second composition means is attached to said lower sealing material.

An article, as claimed in any one of claims 12 to 14, wherein said lower sealing material has standoff means for separating said first composition means from said second composition means.

16. An article, as claimed in any one of claims 1 to 15, comprising a plurality of said articles which are substantially linearly positioned, adjacent said articles being interconnected.

17. An article, as claimed in claim 1, wherein said first composition means comprises an alkali metal chlorate and nitrocellulose.

18. An article, as claimed in claim 17, wherein said alkali metal is selected from the group consisting of potassium or sodium.

19. An article for moving a member comprising a friction-sensitive ignitable first composition means; a second composition means, physically distinct from said first composition means for igniting said first composition means when movement of the member is desired, and external casing for containing said first and second composition means within said casing means, which article is substantially as herein described with reference to Figure 1, Figure 1 and Figure 2, or Figure 3. Dated 28 June, 1995 Sencorp Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON I •I -r ''Si [N:\libff]00226:LMM x i- i r Apparatus and Composition for Propelling an Object Abstract of the Disclosure A charge assembly apparatus for propelling an object such as a fastening element. One embodiment generally includes a propellant charge (42) and a separate sensitizer (46) which are substantially totally encased within a substantially non-rigid carrier strip A plurality of these charge assemblies may be sequentially positioned within the carrier strip (10) such that the present invention may be used with a fastening element driving apparatus in high production applications. Nhen used in this application, the sensitizer (46) is mechanically impacted by for instance, a firing pin. The sensitizer (46) is then driven into engagement with the propellant charge (42) such that sufficient friction is created to ignite the propellant charge. The gases produced by combustion of the propellant charge therefore generate sufficient forces to propel the fastening element from the fastening element driving apparatus in the desired manner. Figure 3. i i i1 1368W/GMM i