Elongated-member-driving apparatus – Explosive-type driving means – With plunger
Patent
1990-01-10
1991-09-17
Yost, Frank T.
Elongated-member-driving apparatus
Explosive-type driving means
With plunger
B25C 114
Patent
active
050487400
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to explosively actuated tools for setting fasteners such as nails or pins into a substrate composed of a relatively hard material such as concrete, masonry, or steel.
FIGS. 1 to 4 show an explosively actuated setting tool of the type disclosed in U.S. Pat. No. 3,066,302. In these figures, FIGS. 1 and 2 show respectively, a receiver assembly and a barrel assembly, and FIG. 3 shows the barrel assembly mounted in the receiver assembly, with the tool ready to fire. FIG. 4 shows the barrel assembly pulled into a forward position to open a breach of the tool for re-setting a firing piston and for loading a fresh charge.
The barrel assembly comprises a barrel 2 containing a firing piston 4. A charge chamber 6 at the rear of the barrel 2 receives an explosive charge 8 which is fired by a firing pin 10 in the receiver assembly (FIG. 1) to propel the piston 4 forwardly to drive a fastener 12 positioned in the forward end of the barrel into a substrate. A slot 14 formed in the underside of the barrel 2 is adapted to receive a spring-loaded stop pawl 16 for re-setting the piston 4 after firing, the pawl 16 being carried at the front end of the receiver assembly. At the forward end of the slot 14, a cam surface 18 acts to displace the pawl 16 out of the path of the piston 4 when the barrel 2 is in its rearward, ready-to-fire position as shown in FIG. 3. When the tool has been fired, the piston 4 normally stops with its head 4a positioned just behind the pawl 16, this stop position being obtained when the forward end of the piston 4 is at the forward end of the barrel 2, with the fastener having been driven fully home into the substrate so that its head flush with the surface of the substrate. The cam 18 displaces the pawl 16 out of the possible path of the piston head 4a in case the piston 4 over-drives the fastener into the substrate should the substrate be unusually soft.
In order to reset the tool after firing, the barrel assembly is moved forwardly into the position shown in FIG. 4. At the start of this movement, the cam 18 moves with the barrel 2 forwardly away from the pawl 16 thus allowing the pawl 16 to move upwardly through the slot 14 to engage the front face of the piston head 4a and prevent the piston 4 moving forwardly with the barrel 2. When the barrel is in its forward position (FIG. 4), the piston head 4a is at the back end of the barrel 2 and has thus been reset relative to the barrel 2 in preparation for the next firing. In the forward position of the barrel 2 the breach 20 is opened behind the barrel 2 to permit extraction of the previous charge 8 and loading of the fresh charge.
In this previously proposed tool, the pawl 16 always lies within the slot 14 in the barrel 2, but in the rearmost position of the barrel 2 (the ready-to-fire configuration of the tool), the pawl 16 is held by the cam 18 out of the possible path of the piston head 4a. The length of the slot 14, and thus the degree of opening of the barrel is determined by the maximum length of fastener which can be driven by the tool. Tools designed for relatively short fasteners accordingly have only a limited degree of opening, and hence only a restricted access which may cause difficulties in removal of the fired charge and loading of the fresh change. These difficulties become apparent for operatives who wear protective gloves and/or work in cold conditions.
According to the present invention, there is provided an explosively-actuated tool for setting a fastener into a substrate, comprising a body, a barrel containing a firing piston operative upon detonation of an explosive charge to drive a fastener in the forward end of the barrel, said barrel being movable in the body from a rear position in which the tool is ready to fire to a forward position in which a breach is opened for loading of a fresh charge and stop means carried by the body and extendable into the barrel to engage the piston during the forward movement of the barrel to reset the piston rearwardly relative to the barrel in preparation for the n
REFERENCES:
patent: 3066302 (1962-12-01), De Caro et al.
patent: 3168744 (1965-02-01), Kvalve
patent: 3549074 (1970-12-01), Brunelle
patent: 3565313 (1971-02-01), Mittelfeld et al.
patent: 3820703 (1974-06-01), Rangger
patent: 4364506 (1982-12-01), Schneider
Husar John M.
Ramset Fasteners (Aust.) Pty. Limited
Yost Frank T.
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