US3805516A

US3805516A - Cartridge actuated tools

Info

Publication number: US3805516A
Application number: US00219678A
Authority: US
Inventors: G Eastham; T Smith
Original assignee: UK Secretary of State for Defence
Current assignee: UK Secretary of State for Defence
Priority date: 1971-01-21
Filing date: 1972-01-21
Publication date: 1974-04-23
Anticipated expiration: 1991-04-23
Also published as: GB1352065A

Abstract

A cartridge actuated tool, in which a tool-head is operated by movement of a piston within a gas-tight pressure chamber under the action of gas pressure produced by the firing of a cartridge, incorporates valve means inoperable before release of the trigger by which the gas can be retained within the pressure chamber until cooling reduces the pressure sufficiently to permit comparatively noiseless exhaust of gas from the pressure chamber.

Description

D United States Patent 1191 1111 3,805,516 Eastham et al. Apr. 23, 1974 [5 CARTRIDGE ACTUATED TOOLS 2,204,308 6/1940 l-lerzmark 60/261 x 4 [75] Inventors: Gerard Eastham, Chorley; Thomas v 23:22a H Gordon smith Allbwme, both of 3,540,141 11/1970 Butler 1' x England 7 3,686,858 8/1972 Termet 60/26 1 X [73] Assignee: The Secretary of State for Defense in Her Britannic Majesty? Primary Examiner-Wendell E. Burns Government of the Umted Kmgdom Attorney, Agent, or Firm-Stevens, Davis, Miller & of Great Britain and Northern Mosher Ireland, London, England 22 Filed: Jan. 21, 1972 12 1 App1- 19 78 57 ABSTRACT A cartridge actuated tool, in which a tool-head is op- [301 Forelgn Apphcation' Priority Data erated by movement of a piston within a gas-tight Jan. 21, I971 Great Britain 2900/71 pressure chamber under the action of gas pressure produced by the firing of a cartridge, incorporates 52 valvermeans ill-operable before release of the trigger Int. Cl. the g can be retained within the pressure of Search chamber until cooling reduces the pressure sufficiently to ermit com arativel noiseless exhaust of gas from [56] References Cned. the pressure clfamber. y

UNITED STATES PATENTS 1,915,435 6/1933 Miller 60/26.l x V 10 Claims, 3 Drawing Figures 7 3 4 2 9 3 IO 6 l4 /I am \L/ 1 1 1 1 1 34 I 1 11 as 1 I 1 3a 111,

2, 1 \g L, w I 23 .1 s V 2O s I 40 PATENTEDAPR 23 mm 38055165 SHEET 2 BF 3 FIG.2.

PATENTEDAPR 23 1974 SHEET3UF 3 3805516 FIG. 3.

1 CARTRIDGE ACTUATED TOOLS This invention relates to cartridge actuated tools, and in particular to tools which are capable of producing a high pressure sustained for a sufficiently long period of time to permit the associated use of a crimping or like tool.

The invention comprises a cartridge actuated tool wherein gas produced by the cartridge when fired is confined within a substantially gas-tight chamber, and which gas generates pressure required to operate a tool head attached to or forming part of the tool; and means for releasing said gas pressure after a suitable delay.

By this latter means the gas can be retained within the chamber until the gas, initially at a very high temperature following the firing of the cartridge, has cooled sufficiently to cause the pressure to fall to such an extent. that the exhaust gas escapes at a sub-sonic velocity, and the resultant absence of a-shock wave en'- sures that the tool is relatively silent in operation. In practice, it has been found that the time needed for the gas to remain in the chamber is shorter than the time of an operators action in actuating and releasing a firing mechanism, so that the speed of operation of the tool need not be significantly reduced.

The type of cartridge employed will depend on the size of tool, and the use to which the tool is being put, but when used in conjunction with a crimping t'ool head it has been found preferable to employ a relatively slow burning cartridge, so that the pressure imparted by the tool head increases steadily for a time perhaps of the order of a tenth of a secondsufficient to allow plastic flow to take place in the material being worked upon. When used to join aluminium electric power conductors, a greatly improved electrical contact has resulted when plastic flow has taken place within the conductors.

The invention can take many forms, one of which is a breech and stock similar in appearance to, a pistol, in which the cartridge, in a' sealed chamber as hereinbefore described, is fired as a result of a trigger being pressed: the gas maythenbe released, for example, as a result of the release of the trigger. In this way, the tool is completely independent of an external power source, although an arrangement whereby the cartridge is'activated by an electrically fired cap or other means may be used, as in any other form of the invention.

By way of example, particular embodiments of the invention will now be described with reference to the accompanying drawings, where:

FIG. 1 is a view of the underside of a tool,

FIG. 2 is a section on the line II II of FIG. I, and

FIG. 3 is a section similar to that of FIG. 2 of a'modified tool incorporating alternative exhaust and firing arrangements. 7

Each embodiment described takes the form of a breech, stock and trigger mechanism similar in appearance to a pistol, adapted to be used for crimping cable terminations and jointing sleeves to aluminium conductors, and is shown fitted for this purpose at its forward end to a typical G-type crimping head 1 into whicha die is fitted. I

Referringto FIGS. 1 and 2, the breech body 2 comprises a pressure chamber 3, within which is locateda piston 4, and a cartridge holder 5, in which a cartridge 6 may be inserted. The piston 4 is normally retained in 2 its rearrnost position by means of a compression spring 7 and retaining collar 8, which allows the desired forward movement of the piston.

One or more piston rings 9 fitted to the piston may be made of any suitable material such as a PTFE- Bronze combination or synthetic rubber, according to the application.

The cartridge holder 5 is fitted with a grid 10 which prevents the main propellant charge from leaving the cartridge case when the end closure disc of the cartridge becomes consumed, and ensures the required burning rate of the propellant and generation of gas pressure.

It is necessary to make provision for the loading and unloading of a cartridge and for removing the cartridge holder for cleaning. For this purpose, the breech body 2 is adjoined to the stock 11 by a pivot screw 12, which allows the stock 11 to be pivoted away from the breech body 2 thus exposing the cartridge holder 5. Means are provided for holding the breech body 2 and stock 11' together in position while firing, said means comprising a locking latch 13, held in the locked position by a compression spring I4, housed in the upper section of the breech body 2 and engaging in a hole 15 in the upper part of the stock 11.

Gas venting mechanism is provided in the breech body 2, whereby gas is released to atmosphere from the pressure chamber 3, first through a vent hole 16 positioned at the rear of the pressure chamber and thence via a small valve orifice 17 which is opened and closed by movement of a plunger 18, located in a small bore 19 beneath the pressure chamber 3, its closure being induced, against the action of a valve spring 20, by the firing movement of the trigger 21. Provision may be made whereby the gas can be piped away from the operator upon emerging from the valve orifice 17 at' the side of the breech body 2.

A flat 22in the side of the plunger 18 locates against one endof the trigger 21 so that, as the trigger is pulled to fire the cartridge 6, the plunger 18 moves forward against the action of the valve spring 20 and blanks off the valve orifice 17, thus sealing the pressure chamber 31 When the trigger is released after the cartridge'has fired, the plunger 18" moves back and releases the gas. Arr operators normal action produces a sufficient delay to enable the operation to be completed without the production of explosive noise, although the operator can continue to press the trigger if he so desires, to ensure a much lower residual pressure in the system at the instant of release.

In the event of the plunger 18 sticking in the closed position, due, for example, to a build-up of deposits, means are provided whereby the plunger 18 can be released, said means comprising a small cam plate 23and an operating'handle 24. By rotation through l from the normal operating position, the cam plate 23'may be used to move the plunger 18 to or maintain it inthe valve-open position and can therefore also be employed to prevent any movement of the trigger 21 and thus to act as asafety catch.

In the released position, the trigger 21, mounted in the stock 11 of the tool and protected by a trigger guard 25, rests against a stop 26 also mounted in the stock 11. As the trigger is pulled back, it pushes a firing plunger 27 through a small free movement to contact a hammer release rod 28 which on further movement of the trigger 21 actuates a hammer 29 via a sear 30.

The purpose of the said small free movement is to ensure that the valve orifice 17 is closed before the cartridge is fired. When the trigger is in the released position, the firing plunger 27 is held against the trigger and clear of the hammer release rod 28 by a return spring 31.

The cartridge 6 is ignited by a percussion cap, which is itself ignited when hit by a striker 32, mounted in the stock 1 1 directly behind the cartridge case and retained in its bore by a retaining pin 33. The striker 32 is normally held back from the cartridge cap by a small striker return spring 34 and only strikes the cap when hit by the hammer 29.

The hammer 29 is mounted alongside a hammer plate 35 on the same pivot pin 36, and the hammer and hammer plate are interconnected by a hammer pin 37 set in the hammer 29 and protruding into a hole 38 of larger diameter than itself in the hammer plate 35, this arrangement permitting a small rotary movement of the hammer relative to the hammer plate. When free, the hammer plate 35 is held in an upright rest position against the stock by a torsion spring 39, whilst at the same time the hammer 29 is held in contact with the striker 32 without forcing the striker forward.

However, when the hammer 29 and hammer plate 35 are pulled back and suddently released momentum carries the hammer 29 additionally forward beyond the aforesaid rest position through the small movement permitted relative to the hammer plate 35 and forces the striker 32 on to the percussion cap to ignite the cartridge 6. When the hammer plate 35 and hammer 29 are pulled back to their extreme position, the hammer plate engages with the sear 30, which is mounted on a sear pivot pin 40 and held in engagement with a detent 41 on the hammer plate 35 by a torsion spring 42.

The sear 30 is also pivotally connected to the hammer release rod 28, so that when the trigger 21 is pressed to move back the hammer release rod 28, the sear 30 is rotated about the sear pivot pin 40 and moved out of engagement with the detent 41 resulting in firing of the cartridge.

Reference is now made to FIG. 3 which shows a modified arrangement.

To reduce the stress on the pivotal connection 46 between the stock 11a and the breech body 2a, the cartridge holder a is screwed into the breech body, so that when a cartridge 6a is fired the consequent reaction is restricted to the area of the cartridge. To provide additional support, the stock 11a has a portion 47 which engages with a recess 48 in the breech body 211.

To facilitate the removal of a spent cartridge from the cartridge holder 5a, the pivotal connection 46 between the stock and breech body is positioned away from the centre axis of the tool, we that on being pivoted the stock moves initially away from the breech body. A ring-shaped extractor 49 surrounding the exposed end of the cartridge can be withdrawn by hand to extract the cartridge from the cartridge holder.

The gases resulting from the firing of the cartridge 6a exhaust to atmosphere through a vent-hole 16a and an axially symmetrical exhaust chamber 50 having a small orifice 51 in its wall. A sealing plug 52 is contained in the exhaust chamber, held in place by being screwed in a boss 53. The sealing plug 52 incorporates at one end a circular seal 54 and at the other end a handle 55, rotation of which causes the sealing plug 52 to move axially within the chamber 50. When the sealing plug 52 is at one end of its axial movement the circular seal 54 abuts against an end of the exhaust chamber preventing passage of gas through the vent-hole 16a, in which position a recess 56 in the sealing plug 52 is aligned with a bore 5a in the breech body, in which a safety rod 58 is slidably mounted. The safety rod 58 is spring-loaded to abut against a projection 59 of the trigger 21a, and the trigger can only be pressed if the rod can move into the recess 56 in the sealing plug 52, ie if the sealing plug 52 is in the position preventing the exhaust gases from escaping. After firing, the exhaust gases are released, subsequent to release of the trigger, by manual rotation of the handle 55, causing the sealing plug 52 to move axially and permit the exhaust gases to pass through the orifice 51.

The firing mechanism operates as follows: a sear 60, retained by a sear pin 61 locating in a recess 62 in the sear, is pivotally connected to the trigger 21a and urges by a spring 63 against a hammer 64. As the trigger 21a is pulled, the sear 60 moves upwards, pushing the hammer 64 back against the action of a hammer spring 65 until a projection 66 on the sear 60 abuts a striker 32a. At this position, the sear 60 and hammer 64 come out of engagement permitting the hammer 64 to come forward under the action of the hammer spring 65 and strike the sear projection 66, forcing the-striker 32a on to the percussion cap to ignite the cartridge 6a.

It will be seen that thetwo embodiments described differ in certain other minor features, which do not however alter the mode of operation, and it will be clear that the different piston, exhaust and firing arrangements are independent of one another, so that, for example, the exhaust arrangement of one embodiment may be used with the firing arrangement of the other whilst remaining within the scope of the invention.

We claim:

1. A cartridge actuated tool incorporating a toolhead, a substantially gas-tight pressure chamber, an actuating piston slidable within the pressure chamber for operating the tool-head and actuated by gas pressure produced by firing of a cartridge, firing means for firing the cartridge, a trigger for operating the firing means, a valve through which the gas can be exhausted, closure means for the valve and means cooperating with the trigger for preventing the valve from opening until the trigger is released.

2. A cartridge actuated tool as claimed in claim 1 in which the means cooperating with the trigger comprises a rod movable by the trigger against the action of a return spring, which rod maintains the closure means in the valve closed position while the trigger is held in the pulled position.

3. A cartridge actuated tool as claimed in claim 2 in which the valve closure means comprises a valve piston attached to and movable with the rod which valve piston closes a vent-hole in the pressure chamber when the trigger is in the pulled position.

4. A cartridge actuated tool as claimed in claim 3 in which the valve comprises a cylinder within which the valve piston is slidable and with which the vent-hole communicates and in whose wall is an orifice open to atmosphere, the valve piston being movable from a position in which exhaust gas can pass from the vent-hole to the orifice to a position preventing the said passage of exhaust gas.

5. A cartridge actuated tool as claimed in claim 2 incorporating a stop device by which the rod can be engaged to retain the tool in the valve-open position.

6. A cartridge actuated tool as claimed in claim 5 in which the stop device incorporates a cam which is arranged to engage the rod and return it to the valveopen position in the event of the return spring failing to operate.

7. A cartridge actuated tool as claimed in claim 2 in which the valve incorporates a chamber and sealing means movable within the chamber and operable manually to open and close the valve.

8. A cartridge actuated tool as claimed in claim 7 in which the sealing means has a recess which is aligned with the rod when the valve is in the closed position, whereby the rod engages in the recess when the trigger is pulled to prevent opening of the valve before release of the trigger.

9. A cartridge actuated tool as claimed in claim 1 in which the firing means incorporates a striker and a spring-loaded hammer operable on pulling the trigger for actuating the striker.

\ 10. A cartridge actuated tool as claimed in claim 9 incorporating a sear pivoted to and movable by the trigger to engage and raise the hammer, which is released by disengagement of the sear and which is spaced from the striker, the sear being movable during operation of the hammer into the space between the hammer and the striker, whereby on disengagement of the sear from the hammer the hammer strikes the sear to actuate the striker.

Claims

1. A cartridge actuated tool incorporating a tool-head, a substantially gas-tight pressure chamber, an actuating piston slidable within the pressure chamber for operating the tool-head and actuated by gas pressure produced by firing of a cartridge, firing means for firing the cartridge, a trigger for operating the firing means, a valve through which the gas can be exhausted, closure means for the valve and means cooperating with the trigger for preventing the valve from opening until the trigger is released.

6. A cartridge actuated tool as claimed in claim 5 in which the stop device incorporates a cam which is arranged to engage the rod and return it to the valve-open position in the event of the return spring failing to operate.

10. A cartridge actuated tool as claimed in claim 9 incorporating a sear pivoted to and movable by the trigger to engage and raise the hammer, which is released by disengagement of the sear and which is spaced from the striker, the sear being movable during operation of the hammer into the space between the hammer and the striker, whereby on disengagement of the sear from the hammer the hammer strikes the sear to actuate the striker.