US3473718A - Explosive-actuated tools - Google Patents

Description

Oct. 21, 1969 R. D. WACKROW 3,473,718

EXPLOSIVE-ACTUATED TOOLS Filed Nov. 21, 1966 2 Sheets-Sheet 1 IN VE/V 7'0R ROGER DA V/D WAC/(ROW ATTORNEYS Oct. 21, 1969 R. D. WACKROW 3,473,718

EXPLOSIVE-ACTUATED TOOLS Filed Nov. 21, 1966 2 Sheets-Sheet 2 IN VE/V 70R ROGER DA V/D WAC/(ROW ATTOR/VEKS United States Patent US. Cl. 227 4 Claims ABSTRACT OF THE DISCLOSURE An explosive-actuated tool for driving anchoring members into hard materials comprising a body having a piston movably mounted therein and a chamber formed at one end of the body, the head of the piston being movable into the chamber which has a stop means at the end thereof to limit piston movement. A locking cap is releasably secured on the end of the body and axially movable relative thereto. The cap supports a cartridge adjacent the body chamber and includes resilient means which normally restrains axial movement of the cap relative to the body and thereby holds the cartridge away from the chamber stop means and the piston head abutting thereagainst. The cartridge will only be fired when the piston abuts the stop means and when an end force is applied against the cap to overcome the restraining force of the resilient means.

This invention relates to explosive actuated tools for driving nails, studs, pins, bolts and other members, hereinafter referred to as anchoring members, into hard materials.

Such tools normally comprise a cartridge supporting member and a cartridge striking member which are relatively moveable into and out of contact so that sudden contact between the two members caused by a blow delivered to one of the members causes a cartridge located in the cartridge supporting member to be fired. The expanding gases of the fired cartridge then normally drive a piston along a tube, this action driving an anchoring member out of the tube and into a wall or the like. The cartridge striking member is normally part of the piston, usually in the form of a firing pin secured to one face of the piston or in the form of a suitably shaped piston face. The cartridge supporting member may be a further piston or may form part of an end cap releasably secured to the body of the tool.

It has been found desirable to provide explosiveactuated tools with safety devices to prevent accidental or inadvertent firing of the tool during normal working and handling operations, and it is an object of the present invention to provide means for preventing the inad vertent firing of an explosiveactuated tool on occas sions such for example as when the tool is knocked, dropped from a reasonable working height or when an attempt is made to load an excessively large anchoring member into the tool.

According to the present invention an explosiveactuated tool for driving anchoring members into hard materials has a body in which are moveably mounted two members, one member being adapted to support a cartridge and the other member to strike the cartridge, there being provided in the body stop means for preventing the first member from moving into contact with the second member, and resilient means for preventing the second member from moving into contact with the first member until such resilient means is compressed, deformed or otherwise overcome.

Preferably the member adapted to support the cartridge comprises an end cap which is releasably secured to the end of the body and is normally held a short distance clear of the end of the body by a spring mounted between the end cap and the end of the body.

A plunger may also be used in conjunction with the spring, and the plunger may additionally serve to pro- ;ide resistance to rotation of the end cap relative to the ody.

The member which is adapted to strike the cartridge preferably comprises the head of a piston which is adapted to drive an anchoring member into a wall or the like when the cartridge is fired.

The piston is preferably prevented from moving into contact with the end cap by means of a suitable stop formed on the end of the body.

The tool can only be fired when the piston and the end cap contact each other, and this may only occur when the piston is held firmly against the stop at the end of the body and the end cap is struck hard enough to overcome the spring. An impact on the piston alone will not fire the tool (provided the end cap spring is not depressed) as the piston will merely hit the stop at the end of the body, and similarly an impact on the end cap alone hard enough to overcome the spring will not fire the tool if the piston is not held firmly against its stop at the same instant. The tool is thus provided with an effective safely device.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which:

FIG. 1 is an external view of the complete tool,

FIG. 2 is a sectional view of the tool, and

FIG. 3 is a sectional view of the tool locking cap on an enlarged scale.

The explosive-actuated tool comprises a body part 1 having a forwardly extending portion in the form of a barrel 2 supported for movement co-axial with the body part by means of a screwed nut 3 engaging an enlarged end portion of the barrel also serving as an abutment for one end of a spring 4a located within the body part 1 and engaging a washer 4.

A piston 5 in the form of an elongated rod or shank enters a bore 6 in the barrel 2 and engages with the head of the stud or nail 10 to be fired, the nail being inserted in a guide member constituting a cap 9 secured to the end of the barrel 2, a recess in the cap receiving a guide washer normally mounted on the nail. A short head portion 7 of the piston 5 is adapted to enter a chamber in the body on a force being applied to the point of the nail 10, the rearward axial movement of piston head 7 in chamber 7a being limited by engagement with the stop shoulder 7b formed at the end of chamber 7a. When the rim of a cartridge located in a locking cap 11 is struck on impact with the piston head 7, the cartridge is fired and gases are passed into the chamber 7a behind the piston.

The body part 1 of the tool is surrounded by a hand grip 8, and terminates in the aforesaid locking cap 11 which is releasably secured to the body by means of alternate shoulders 12 and recesses 12:: on both the body and the cap, a clearance between the shoulders and recesses providing for an axial movement of the cap relative to the body when the cap is struck by a hammer to cause the piston head 7 to detonate a cartridge. As seen in FIG. 3, complete rotation of the cap relative to the body for locking and unlocking is prevented by means of a stop pin in the form of a split sleeve 13 mounted in a bore formed in the cap, means for normally holding the cap clear of the end of the body comprising a plunger 15 loaded by a spring 16 both mounted in a further bore 14 in the locking cap and retained therein by a grub screw 17. By reason of the contact of the nose of the spring-loaded plunger 15 with the end of the body in conjunction with the resistance to rotation provided by the stop pin, an impact on the locking cap will not fire the tool as aforesaid unless it has been adequate to overcome the plunger spring by a deliberate hammer [blow on the cap sufiicient to bring the cartridge into contact with the piston after the tool has been brought to the firing position by pressing it against a wall or other object into which the nail or stud is to be driven.

In operation, the locking cap 11 is released from the body part 1 of the tool by a part rotation to align the alternate shoulders 12 and recesses 12a, a cartridge is inserted, and the cap reconnected to the body by a part rotation to engage the aforesaid shoulders and recesses, such rotation of the cap 11 into the locking and unlocking positions being controlled by the pin 13.

A nail 10 is then inserted into the guide member 9 on the end of the barrel 2, and the tool is pressed against the surface into which the nail is to be driven until the member 9 contacts the surface and the head of the nail contacts the end of the piston 5. This movement effected through the hand grip 8 causes the body part 1 to move relative to the barrel 2 against the spring 18, whereby the chamber 7a is moved over the head portion 7 of the piston, movement of the body part 1 being stopped when the piston head 7 contacts with the rear face 7b of the chamber 7a. The tool is now fired by striking the cap 11 with a hammer, which causes the cap to move axially for a short distance against the spring 16 of the plunger 15 until the cartridge is fired on contact with the piston head 7.

What I claim is:

1. An explosive-actuated tool for driving anchoring members into hard materials comprising a body, piston means axially movably mounted in said body, a chamber formed in one end of said body adapted to be entered by said piston means, said chamber means having stop means limiting the movement therein by said piston means, a locking cap releasably secured to said one end of said body and axially movable relative thereto when mounted thereon, said cap having means for supporting a cartridge adjacent said chamber, resilient means restraining axial movement of said locking cap for normally holding said cartridge support means axially spaced from said stop means, whereby said cartridge will not be fired by striking said piston means until said piston means engages said stop means and said end cap is displaced to overcome the restraining force of said resilient means.

2. An explosive-actuated tool according to claim 1, said cap ibeing releasably secured to said body by interengaging shoulders and recesses having axial clearance therebetween to permit axial movement of said cap relative to said body.

3. An explosive-actuated tool according to claim 1, wherein the resilient means comprises a spring loaded plunger located in said locking cap.

4. In an explosive-actuated tool according to claim 1, a stop pin located in said locking cap for preventing complete rotation of said cap relative to said body.

References Cited UNITED STATES PATENTS 2,768,375 10/ 1956 Caflin 227- 11 2,984,836 5/ 1961 Schenkel 227-9 3,055,008 9/ 1962 Bell et al. 227-10 TRAVIS S. McGEHEE, Primary Examiner

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