CA1070901A

CA1070901A - Firing power control for explosively actuated fastener driving power tool

Info

Publication number: CA1070901A
Application number: CA256,038A
Authority: CA
Inventors: Marc Combette; Jean Olliver
Original assignee: Societe de Prospection et dInventions Techniques SPIT SAS
Current assignee: Societe de Prospection et dInventions Techniques SPIT SAS
Priority date: 1975-07-02
Filing date: 1976-06-30
Publication date: 1980-02-05
Also published as: AU1545876A; FR2316050A1; FR2316050B1; ZA763726B; JPS5238683A; JPS5848312B2; SE7607535L; MX143926A; IT1061873B; BR7604348A; BE842761A; AU500246B2; AR208801A1; DE2628814A1; NZ181275A; ES449396A1; GB1540247A

Abstract

Abstract of the Disclosure The invention relates to a power actuated tool comprising an expansion chamber for the combustion gases of a piece of ammunition placed in a combustion chamber. In the tool, at least one substantially radial through hole is provided in the wall of the said expansion chamber or of the said combustion chamber and a bush which moves relative to the said chamber is provided so as to be able to more or less completely expose the said hole.

Description

1~09~1 .

The present invention relates to improvements to power actuated tools used for fixing a fastener in a hard wall, utilising the combustion of a propulsive charge.
Tools of this type can be fired directly, i.e. th~
combustion gases act directly on the back surface of the fastener in order to propel the same. Indirect firing tools also exist in which a cap is placed between the charge and the fastener.
In both cases the propulsive charge can comprise ammunition having a case whose combustion gases expand in an expansion chamber provided between the ammunition and the rear of the fastener or the cap. It has also been proposed to use caseless agglomerated charges placed in a high pressure chamber where the ammunition burns, whereby the said high pressure chamber is connected with a low pressure chamber provided between the ammunition recess and the rear face of the fastener or the cap.
In the case of all these different types of tools and ammunition it is desirable to be able to vary the firing power, particularly as a function of the hardness of the wall in which the fastener is to be introduced. It is obviously possible to use different ammunition types, but the power variations obtained are not flexible and the operator must permanently have avail-able ammunition with different power ratings. ~;
It is also possible for the purpose of varying thepower to modify the volume of the chamber in which the combustion gases expand, i.e. the expansion chamber in the case of a tool with cased ammunition and the low pr~essure chamber in the case ~;
of a tool with caseless ammunition. This latter solution is highly effective but leads to a considerable complication in the construction of the tool. ;

The present invention aims at permitting the easy .
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variation within significant limits of the firing power of the tool using simple and more reliable means than those used hitherto.
The construction in accordance with the present invention includes a power actuated tool comprising a breech, a barrel mounted on the breech and a combustion chamber adapted for the production of combustion gases from a piece of ammuni- ~
tion carried therein. A percussion mechanism lS operatively ~ -disposed to fire the ammunition and an expansio~ chamber communicates between the bore of the barrel and the combustion chamber, while means for varying the effective volume of the ~--expansion chamber to adjust the operating force of the tool is also provided. The percussion mechanism is attached to the breech and both the chambers are carried by the barrel. The means comprising a vent in one of the chambers provides passage for a portion of the gases to the atmosphere and a bush is moveably carried out the chamber having the vent. The bush includes at least one through opening adjustably alignable with the vent, whereby flow of the gases therethrough may be ~ `~
controlled.
The device acaording to the invention makes it possible to obtain a more or less qignificant escape of combustion gases permitting the variation of the firing power from a minimum value to a maximum value.
According to one embodiment of the invention the said bush is screwed to the barrel.
According to a variant the said bush is fi~ed in translation relative to the said barrel and rotates about the -~
barrel axis. - -~
According to another variant an independent ammunition holder can be provided which is supported on the free end of the `~
said bush, preferably the hole or holes are provided in a rear

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smaller diameter portion of the barrel, whereby the said bush is screwed to a larger diameter portion of the ~arrel and has an internal shoulder arranged so that it can co-operate with the shoulder provided on the barrel between the said smaller diameter portion and the said larger diameter portion.
In the case of an exclusively rotary bush, it is advantageous for the said bush to have an inde~ing means, for example, a ball returned by a sprin~ and co-operating with recesses in a fixed portion adjacent to the -tool.
According to one embodiment the hole or holes in the bush are flared whilst diverging from the axis.
According to a variant the bush has a plurality of holes in the same radial plane and having different diameters.
It is also preferable for the bush periphery to be at least partly vented.
The invention will be better understood from reading the following description with reference to the attached draw-ings wherein~
FIGURES 1 to 3 show, in longitudinal section for various position of use, a first variant of a tool according to the invention~
FIGURES 4 to 6 show a second variant of the tool according to the invention;
FIGURES 7 to 9 show a third variant, FIGURE 10 shows a further variant; ~;
FIGURES 11 A, B, C show sec-tional views along the line XI - XI of Figure 10 for three different settings' FIGURES 12 and 13 show two variants of the tool of Figure 10;
FIGURES 14 A, B, C are respectively similar to Figures 11 A, B, C, but for the tool of ~ ;

Figure 13.;

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FIGURE 15 is a fragmented lonyitudinal sectional view of a direct firing tool using cased ammuni- : :?
tion and having a rotary bush similar to that shown in Figure 10 FIGURE 16 is a fragmented longitudinal sectional view .
similar to Figure 13, bul; showing ths ~:
invention used in connection with direct firing tool; ;;~
FIGURE 17 is a fragmented longitudinal sectional view -of a direct flring tool embodying a variation ~-of the invention including a rotation , indicator of the ball detent type, ~FIGURE 18 iS a fragmented longitudinal sectional view :
of a direct firing tool similar to that shown in Figure 15, but modified to permit ;
- insertion of the fastener into the barrel ~
through the breech end thereof, ; - .
FIGURE 19 iS a fragmented longitudinal sectional view :, of a modified tool made in accordance with the invention wherein the power setting ~.- , -mechanism is combined with an exhaust chamber to provide for controlled escape ~ :~
of combus~n gases, : .
FIGURE 20 is a fragmented longitudinal sectional view of a modified tool made in accordance with the invention wherein the power setting ~ ~ .
adjustment may be made from the rear of the tool while the breech thereof is closed, .
FIGURE 21 i5 a fragmented longitudinal sectional view of a modified tool made in accordance with .
the invention wherein the power adjustment .

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is made b~ acting on the low pressure chamber, the power setting being shown at its lowest value, and FIGURE 22 is a view similar to Figure 21 showing ~ :
the power setting of the tool at its hig~est power setting. ;
Reference should first be made to Figures 1 to 3 which show a direct firing tool using cased ammunition. The ~.
tool comprises a breech 1 having a percussion system 2 with a percussion striker 3r A barrel 4 is slidingly moun-ted and pivots relative to breech 1. This permits the loading from the rear of a sealing fastener 5 into the channel 6 of the barrel, whereby the said channel has a larger diameter rear .
end 7. The tool also comprises an independent combustion i, .
chamber 8a with an axially aligned through bore in the ammu- :~
nition holder 8 which alsois intended to receive a piece of cased ammunition 9. A not shown pusher rod can be provided for extracting the case after combustion of the charge. The ammuni-tion holder 8 has an end 8~ whlch penetrates the portion 7 of .
20 channel 6. .
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A radial duct 10 opens into portion 7 of channel 6 ~
and a bush 11, equipped with a radial hole 12 is screwed to ~:
the rear threaded end of barrel 4. Depending on the degree to which bush 11 is screwed to barrel 4 extension 8' of ammunition holder 8 penetrates to a greater or lesser extent into portion .7 of channel 6. .
When bush 11 is screwed right down onto barrel 4 ..
(Figure 2) the front end of extension 8' abuts directly against . ;
the bzse of portion 7 of channel 6, and the rear of fastener 5 is substantiàlly in contact with the front end of extension 8',~ `~

so that the expansion volume of the combustion gases is minimal (substantially zero) and the firing power is maximum.

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As soon as the bush is slightly unscrewed a volume 13 -~
(Figure 3) is provided between the rear end of fastener 5 and the front end of extension 8' so that the firing power decreases.
After a predetermined unscrewing of bush 11 the volume of duct ~;
10 is added to volume 13 which further decreases the firing power.
Furthermore, by angularly displacing bush 11 relative -:, .
to barrel 4, hole 12 in the said bush is made to correspond to ~ f a greater or lesser extent with duct 10. Hole 12 substantially issues into the open air so that the expansion volume increases ~;
until a maximum volume is reached corresponding to the position of Figure 3, wherein the firing power is minimal.
Reference should now be made to Figures 4 to 6 which , . ...
show an indirect firing tool using cased ammunition. The same reference numerals designate the same components as hereinbefore.
In this embodiment barrel 4 has an axial bore 14 in which slides ;~, a cap 15 terminated at the rear by a portion 16 which slides in a rear extension 17 of bore 14 but whose diameter is smaller - .. .
than the said bore. Cartridge 9 is located in combustion chamber ~ -8a in extension 17 and its case is extracted after combustion and opening the tool, by the return of the cap. Portion 16 can be eliminated and the case is then extracted by means of an extractor.
A bush 11 provided with a radial hole 12 is screwed onto the rear of barrel 4 and has an inner shoulder 18 striking ; ~
against an outer shoulder 19 of barrel 4. When shoulders 18 ;`
and 19 abut against one another (Figure 4) the expansion volume -~
of the gases, comprising the volume of duct 10, is minimal and the firing power maximum. When bush 11 is sllghtly unscrewed the annular volume 20 provided between shoulders 18 and 19, with which communicates duct 10, is added to the expansion volume and the firing power decreases (Figure 5). After a predetermined - 6 ~

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unscrewing of bush 11 hole 12 projects more or less completely beyond shoulder 19 and the expansion volume is vented to correspondingly varying degrees. In the position of Figure 6 the firing power is minimal. ~;~
It should be noted that in this embodiment the venting of the expansion volume takes place into annular volume 20. In the embodiment of Figures 1 to 3 however, the venting can only take place in one angular position of the bush, making it necessary to provide a visual indicating system, not shown, such that marks on barrel 4 and on bush 11 indicate the co-incidence of the axes of duct 10 and hole 12.
The embodiment of Figures 7 to 9 is similar to that of Figures 4 to 6, except that the tool has a direct firing action so that it has no cap. The same reference numerals designate the same components as in Figures 4 to 6. Figure 7 shows the minimum power position with a maximum expansion volume and venting. Figure 8 shows a medium power position without venting, whilst Figure 9 shows a maximum power posi-tion with a minimum expansion volume without venting. The -ammunition case is extracted by an extractor after combustion.
Figures 10 and llA, B and C show a variant of the -~
tool according to the invention, for a direct firing system with cased ammunition. In this variant bush 11 is no longer screwed to barrel 4 but solely rotates with no possibility of ; ; -axial displacement. To this end, bush 11 is maintained agalnst longitudinal movement with respect to the barrel 4 by a ring 21 secured to the barrel 4. Bush 11 has three radial holes 12, 12' and 12", located in a same radial plane and having different diameters. The angular position of bush 11 relative to barrel 4 is marked by a ball 22 biased by a spring 23 and co-operating with slots provided in the tool.

In the angular position of Figure llA, none of the ~

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holes 12, 12' and 12" faces duct 10 and the firing power is ;
maximum. In the position o~` Figure llB the smallest di meter hole 12" faces duct 10 and the firing power is medium. For another position, not shown, where the medium diameter 12 faces duct 10 the power is lower than in the previous case. Finally ~
in the position of Figure llC the largest diameter hole 12' ;
faces duct 10 and the firing power is minimal.
The embodiment of Figure 12 is identical to that of Figures 10 and llA, B and C, except that cap 15 has a conical rear end 16, as in the case of Figures 4 to 6.
Reference should now be made to Figures 13 and 14A, B
and C which show an indirect firing tool using caseless ammuni~
tion. The caseless ammunition 23 i5 placed in a recess or combustion chamber 24 which opens through the p~riphery of ;~
barrel 4, and into which opens at the rear a passage 25 for the percussion striker 3 and at the front a passage 26 opening onto the rear face of the cap. Bush 11 a~so rotates exclusively relative to barrel 4. To this end, it is located between a shoulder 27 of the barrel and a shoulder 28 of the percussion system 2. Furthermore, a stud 29 integral with bush 11 co- -operates with a peripheral groove 30 of the percussion system ;
2. A ball 31 returned by a s~ing 32 co-operates with slots in bush 11 to assure its marking in the angular position.
The bush 11 can have a plurality of holes as in the case of Figures~10, 11 and 12 but it need only have a single slot 12 preferably widened towards the outside, as shown in Figure 14A, B and C~ In the angular position of Figure 14A, slot 12 does not face the opening of chamber 24. The firing power is then maximum because the high pressure chamber 24 is not vented to the atmosphere. In the angular position of Figure 14B, slot 12 only partly communicates with chamber 24 and therefore the firing power is medium. In the position of .: - , . .

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Figure 14C, slot 12 completely faces chamber 24 and the firing power is minimal. There can obviously be more than three marking positions for bush 11. This embodiment can also be ;
used with the tools of Figures 10 and 12.
The embodiment of Figure 15 relates to a direct ~iring tool using cased ammunition having a rotary bush 11 of the same type as Fig~lre 10. The initial volume of chamber 33 is constant and not zero.
Figure 16 shows a tool which is identical to that of Figure 13, except that it is of the direct firing type.
In the tool of Figure 17 the high pressure chamber 24 is provided in percussion system 2. The marking system of rotary bush 11, which comprises ball 31 and its spri~g 32, co- ~ -operates with slots provided in barrel 4. ;
The tool of Figure 18 is identical to that of Figure ~ ;
15, except that the channel 14 is extended without narrowing up `
to the rear of the barrel, thereby permitting the introduction ... ~ .
from the rear of the fastener.
- In all cases the power setting marks can be used, particularly when a rotary b~1sh is usedl such as that of Figure `
14, so that the operator can see everything whilst using the tool.
It is also possible, with the system according to the invention, to combine the power setting with a controlled escape of the combustion gases.
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i~ For example, Figure 19 shows a tool according to the ~ -,.
invention after firing. In ~his embodiment the bush 11 has a peripheral groove 34 into which opens the radial hole 12. Groove 34 is permanently connected via a duct 35 provided in the butt `~
with an exhaust chamber 36 e~uipped with baffles 37. When the hole 12 faces chamber 24 part of the combustion gases is diverted towards the exhaust chamber 36.

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Figure 20 shows an embodiment of a tool with a pivot- :
ing bush 11 according to the invention, in which the rotation of bush 11 is controlled from the rear of the device, permitting ~ .
the user positioned behind the gun at the moment of firing, to : .
set the power at the desired value whilst remaining in the ~ ;
working position. ~ ~ .
To this end, bush 11 is rearwardly terminated by an arm 38 co-operating with a slot provided in a pivoting member " ~`~
39. Member 39 is rearwardly extended by a tubular portion 40 . ~:
serving as a guide to the percussion striker 3 and having two transverse slots 41. A cover 42 covers the rear of the tool . ~:
and is maintained in place by a washer 43 having a gap whose radius permits co-operation with slots 41 of member 39. I'he ~.
rotation of washer 43 produces the rotation of bush 11 via ~`
member 39, 40. ~ :
When caseless ammunition is used the power can be adjusted by acting on the low pressure chamber. E'igures 21 and 22 show an indirect firing tool using caseless ammunition. `~
Duct 10 faces low pressure chamber 45 and the holes or slot .
12 of bush 11 correspond. Figure 21 corresponds to the minimum . .
power position and Figure 22 to the maximum power position. ~: ~

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. A power actuated tool comprising a breech, a barrel mounted on said breech, a combustion chamber adapted for the production of combustion gases from a piece of ammunition carried therein, a percussion mechanism operatively disposed to fire said ammunition, an expansion chamber communicating between the bore of said barrel and said combustion chamber, and means for varying the effective volume of said expansion chamber to adjust the operating force of the tool, said per-cussion mechanism being attached to said breech, both said chambers being carried by said barrel, said means comprising a vent in one of said chambers providing passage for a portion of said gases to the atmosphere and a bush moveably carried about the said chamber having the said vent, said bush including at least one through opening adjustably alignable with said vent, whereby flow of said gases therethrough may be controlled.

2. In a power actuated tool of the type including a barrel, a combustion chamber adapted for the production of combustion gases from a piece of ammunition carried therein, and a passage for conducting said gases from said chamber to the bore of said barrel; the improvement comprising: means for controllably varying the operating force of the tool, said means comprising a vent in said passage communicating to the atmosphere and a bush moveably carried about said passage, said bush in-cluding at least one through opening adjustably alignable with said vent, whereby flow of said gases therethrough may be controlled.

3. The tool of claim 2, wherein said combustion chamber is moveable relative to said barrel and said bush engages said chamber and said barrel such that displacement of said bush displaces said chamber relative to said barrel, whereby the volume of said passage may be varied.

4. A tool according to claim 1, wherein the said bush is fixed in translation relative to the said barrel and rotates about the said barrel axis.

5. A tool according to claim 1, wherein an independent ammunition holder is provided, supported on said barrel and abutting a free end of said bush, said combustion chamber being formed in said ammunition holder.

6. A tool according to claim 1 or 5, wherein said vent is provided in a smaller diameter rear portion of said barrel, and said bush is screwed to a larger diameter portion of said barrel and has an inner shoulder positioned so as to be able to co-operate with a shoulder provided on said barrel between said smaller diameter portion and said larger diameter portion to limit the displacement of said bush relative to said barrel.

7. A tool according to claim 4, wherein said bush has at least one ball biased by a spring and co-operating with recesses in said breech.

8. A tool according to claim 1, wherein said bush is operatively connected to a rotatable control member located on said breech, whereby said bush may be displaced by rotation of said control member.