US 3744240 A
A tool for driving fasteners and the like into a supporting surface. The tool utilizes a propellant charge which is ignited to produce expanding combustion gases that provide energy for driving a ram member against the fastener. The combustion gases are also used to return the ram member from its driven position to its driving position automatically. The ram member is also releasably held in its driving position before the tool is fired.
Description (OCR text may contain errors)
United States Patent 11 1 1111 3,744,240 Henninget al. 1 July 10, 1973  FASTENER DRIVING TOOL FOREIGN PATENTS OR APPucATloNs lnvemorsr Robert Kenning, North Haven; 916,272 1/1963 Great Britain 60/261! Theodore L- Kucmerosky, 632,610 l2/l96l Canada 60/26.] Northford, both of Conn. 73 A n e: Olin Co ration New H n Primary Examiner-Wendell E. Burns 1 581g e Com m ave Att0rney Donald R. Motsko, William W. Jones et al.
 Filed: Nov. 5, 1971  I ABSTRACT PP N05 1969053 A tool for driving fasteners and the like into a supporting surface. The tool utilizes a propellant charge which 521 US. Cl. 60/26.l, 60/26.ll is ignited to Produce expanding combustion gases that 51 161.01."; F0lb 29/08 Provide energy for driving a ram member against the 581 Field 6: Search 60/26.l, 26.11 fastener- The combustion gases are also used to return the ram member from its driven position'to its driving 5 References Cited position automatically. The ram member is also releas- UNITED STATES PATENTS ably held in its driving position before the tool is fired. 3,645,091 2 1972 lvanov 8! al. 60126.1 2 Claims, 7 Drawing Figures 18 5a /0 31 14( T 56 6 M 2 22 4? 4s 0 1 1 1 l 1 1 1 1 1 1 1/ 1 1 1 111 1 1 1 1 -1 7 i i "J Ni 6' SlEEIlNZ ROBERTWHENN/NG THODORE L. KUCMEROSM INVENTOR BY 41% M ATTORNEY 4 PAIENIED JUL 1 01913 PAIENIED JUL 1 0 m5 MHZNZ ROBERT w. HNN/N THEODORE L. KUC
G MR0$KY INVENTOR BY D ATTORNEY FASTENER DRIVING "root,
This invention relates generally to a fastener-driving tool of the type utilizing the forces created by an explosion of a combustible substance to drive a piston, and more particularly to the problem of returning the piston from its driven position to its driving position.
Many solutions have been offered to the problem of returning a piston from its driven position to its driving position in a power-actuated tool utilizing a charge of ignited propellant as a power source. Such solutions include the use of metallic springs which are compressed by the piston, urethane bellville washer-type springs which are compressed by the piston, and arrangements wherein movement of the tool barrel after firing causes the piston to be returned to its firing position.
The tool of this invention is specifically adapted to utilize the pressurized combustion gases, formed by igniting the propellant charge, to return the piston or ram from its fired position to its firing position. This invention is readily usable with conventional cased propellant charges or the newer caseless propellant charges.
To provide automatic means for returning the piston from its driven position to its firing position, the tool of the present invention is provided with a piston return system which utilizes the gases produced by the explosion of the combustible substance. For this purpose, the barrel insert, the ring member of the piston buffer assembly, and barrel sleeve member are all provided with communicating, axially extending, grooves. A bore extends between the groove in the barrel insert and the interior thereof at a point rearward of where the piston will be located at its final driven position. A bore is positioned in the sleeve member adjacent the ram buffer ring provides communication between the interior of the sleeve and the groove. Thus a continuous duct is provided between the interior of the barrel insert and a point forward of the head portion of the ram.
The rearward portion of the ram is provided with a groove on which is mounted an expandible locking ring. The locking ring serves to retain the ram in its rearward most position by virtue of its expanding into engagement with the rearward surface on the ring member on the piston buffer assembly after it passes therethrough.
In operation, when the pellet is ignited and the combustion gases pass through the gas ports into the low pressure combustion chamber immediately behind the piston, the force of such gas drives the piston and ram forward in the barrel, thereby driving the fastener into the work piece. As soon as the piston passes the bore, the gas immediately moves through the grooves in the barrel insert, piston buffer assembly, and sleeve member, and the bore in the barrel sleeve, forward of the head portion of the piston. The piston member will continue to move forward until it abuts the metallic washer of the piston buffer assembly. However, the ram member will continue to move forward thereafter until its energy is substantially dissipated by the fastening operation or until the head portion bottoms against the urethane buffer member positioned forwardly in the sleeve member. In actuality, since the gas has escaped into the area forward of the head portion at this point, there will be a thin layer of gas interposed between the head portion and the buffer member so that the head portion will not be in direct contact with the buffer member.
When the movement of both the piston and the ram have stopped, the gas pressure in the area behind the piston member will tend to equalize itself with the pressure of the gas within the sleeve in the area immediately forward of the head portion of the ram. The area behind the head portion of the ram at this point is vented to the atmosphere so that during this equalization process, since the gas in the forward portion of the sleeve member is higher than atmospheric pressure, the force of this gas will tend to move the ram rearwardly in the tool until the rearwardly extending portion thereof engages the piston member. At this point, since the crosssectional area of the head portion of the ram upon which the gases act is greater than the rearward surface area of the piston member, the gases will continue to urge the ram member rearwardly, driving the piston member back into contact with the shoulder in the barrel insert. As the ram member moves rearwardly, the locking ring in the rearward extension thereof is compressed by virtue of the chamfer on the forward surface of the buffer assembly until the locking member passes therethrough and can expand into engagement with the forward face of the ring member thereby holding the ram in its proper position.
It is, therefore, an object of this invention to provide a mechanism for returning a power-actuated tool ram member from its driven position to its driving position.
It is a further object of this invention to provide a mechanism of the character described which utilizes as its motive force, the expanding combustion gases which are used to drive the ram member through its work stroke.
It is yet a further object of this invention to provide a mechanism of the character described having disruptable means for holding the ram member in its driving position prior to being fired through its work stroke.
It is another object of this invention to provide a mechanism of the character described having a piston member for driving the ram member, which piston member is movable independently of the ram member.
These and other objects and advantages of the mechanism of this invention will become readily apparent from the following detailed description of a preferred embodiment of the invention taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a side elevation view of a preferred embodiment of a tool formed in accordance with this invention, with portions shown in cross-section, and with the fastener-driving ram and associated piston being shown in their respective driving positions;
FIG. 2 is a sectional view, enlarged for clarity, of that portion of the tool of FIG. 1 which operates to retain the ram member in its driving position;
FIG. 3 is a sectional view of a portion of the ram member showing the manner in which the locking ring is mounted in a groove on'the ram;
FIG. 4 is an end view of the ram member showing the manner in which the retainer ring is laterally split to permit radial flexure thereof within the ram member groove;
FIG. 5 is an exploded perspective view of the barrel insert members which operate to provide the combustion gas bypass conduits to bleed combustion gases from behind the piston member to forward of the ram member;
FIG. 6 is a sectional view of the barrel portion of the tool of FIG. 1 showing the piston member and ram member being driven forward through their work strokes by firing a cartridge, and illustrating the manner in which combustion gases are bled by the ram member to the area downstream thereof; and
FIG. 7 is a sectional view of the barrel portion of the tool similar to FIG. 6 but showing the ram member separated from the piston member and positioned at its driven position.
Referring now to FIG. 1, there is shown a preferred embodiment of the tool of this invention. The tool inv cludes a handle portion 2 which carries a trigger 4 and trigger guard 6. A receiver housing 8 is mounted on the handle 2 for sliding movement thereon, the receiver housing containing a bolt member 10 in which a firing pin 12 is mounted. The firing pin 12 and trigger 4 may be cocked in any conventional manner when the receiver housing 8 is slid rearwardly to open the firing chamber for loading with a propellant cartridge. A barrel member 14 is mounted on the handle 2, the barrel member 14 having a threaded end portion 16 onto which is screwed a muzzle bushing 18 having a bore 20 in which is positioned a fastener to be driven into a supporting surface.
The barrel 14 includes a bore 22 in which is mounted a barrel insert member 24 having a bore 26. A longitudinally extending groove 28 is formed in the exterior surface of the insert member 24, and a passage '30 opens from the insert member bore 26 intothe groove 28. A firing chamber member 32 is fitted into the bore 26 of the barrel insert 24 and includes a bore 34 which is sized to receive a propellant cartridge 36 to chamber the latter for firing by the firing pin 12. A piston member 38 is slidably mounted in the barrel insert bore 26 forward of the firing chamber member 32 and in gassealing engagement with the wall of the bore 26. A barrel sleeve member 40 is mounted in the barrel bore 22 forward of the insert member 24. The barrel sleeve 40 includes a first enlarged bore 42 which opens into a reduced bore 44 aligned with the muzzle bushing bore 20. A longitudinally extending groove 46 is formed in the exterior of the barrel sleeve 40 and is aligned with the barrel insert groove 28, and a port 48 is disposed in the sleeve 40 to provide fluid communication between the groove 46 and sleeve bore 42.
Three annular members 50, 52 and 54 are disposed in the barrel bore 22 and sandwiched between the insert member 24 and the sleeve 40, the member 50 being a metal ring, the member 52 being a polyurethane piston buffer ring, and the member 54 being a metal ring. Each of the ring members 50, 52 and 54 has a groove 56, 58 and 60 respectively formed in its exterior surface and aligned with each other and with the grooves 28 and 46. Thus the port 30, the grooves 28, 56, 58, 60 and .46, and the port 48 combine to provide a combustion gas passage between the insert bore 26 and the sleeve bore 42. A ram member 62 is slidably mounted within the barrel, the ram 62 including a stem portion 64 which extends into the sleeve bore 44, an enlarged head portion 66 positioned within the sleeve bore 42 and in gas-sealing engagement therewith, and a rearwardly extending end portion 68 which extends into the insert bore 26 for engagement with a locating recess 70 formed in the front face of the piston 38. A polyurethane ram buffering ring member 72 is mounted in the forward end of the sleeve bore 42.
Referring now to F lGS. 2-4, a preferred embodiment of a ram retaining mechanism is disclosed. The metallic ring member 54 is provided with an internal oblique or chamfered surface 74 at the forward end thereof, and an undercut notch or groove 75 rearward of the chamfer 74. A ring '76 is mounted in a groove 78 formed on the ram member 62 rearward of the ram head portion 66. The ring 76 is resilient and is laterally split, as at 77, so as to be capable of radial flexure operative to vary the effective diameter of the ring 76. As shown in FIG. 3, the diameter of the ring 76 is such that the ring normally protrudes from the groove 78 above the exterior of the ram 62, and the groove 78 is deep enough so that the ring 76 can be radially compressed sufficiently to be completely contained within the groove 78. In its normal radially enlarged position, the ring 76 is captured by the groove 75, and the ram 62 is thus held in its rearward firing position.
Referring now to FIG. 5, details of the members which are fitted into the barrel bore 22 are shown. The barrel insert 24 is provided with a notch 25 into which fits a tongue 27 formed on the ring 50. The rings 50, S2 and 54 are each provided with notches 51, 53 and 55 respectively, into which fit tongues 29 and 31 formed on rings 52 and 54, and tongue 33 formed on the barrel sleeve 40. The tongue-slot arrangement ensures proper alignment of the grooves 28, 56, 58, and 46 formed in the insert 24, rings 50, 52, and 54, and sleeve 40 respectively, thus ensuring maintenance of the gas passage between the bore of the insert 24 and the bore of the sleeve '46. Referring now to FIGS. 6 and 7, the manner in which the device of this invention operates is set forth. In FIG. 1, as previously noted, the various components of the device are shown in their respective firing positions. A fastener F, to be set in a supporting surface S, is positioned in the muzzle bushing bore 20, and the muzzle of the device is then seated on the supporting surface S, as shown in FIG. 6. The propellant cartridge 36 is then fired creating a rapidly expanding volume of combustion gases G which gases enter the insert bore 26 and drive the piston 38 from its driving position to its driven position where it impacts the metal ring 50. Forward movement of the piston 38 causes the ram 62 to be driven'forward from its driving position. The piston force acting upon the ram 62 causes the ring 76 to be radially compressed and frees the ring 76 from the confines of the retaining groove 75. As the piston 38' moves forward in the insert bore 26, it opens the port 30 to the high pressure combustion gases G. The gases G are then free to pass through the port 30, the grooves 28, 56, 58, 60, and 46, and the port 48 so as to enter the sleeve bore 42 forward of the ram head 66. The
path of this bleed-off flow of pressurized gases is denoted generally by arrows A in FIG. 6. In this manner a pocket of pressurized combustion gases is established in the sleeve bore 42 forward of the ram head 66. Forward movement of the piston 38 also uncovers a vent port 39 which vents pressurized combustion gases to the atmosphere from the insert bore 26 when the piston 38 reaches its fired position.
Forward movement of the piston 38 stops when it strikes the ring 50, after which forward movement of the ram 62 continues. The stem portion 64 of the ram 62 moves against the fastener F and drives the latter into the supporting surface S. The combustion gas pocket forward of the ram head 66 is further compressed by the advancing ram head and acts as a fluid spring to slow and stop the advancing ram 62. The port 48 is closed off by the advancing ram head 66 so that the compressed gas is trapped forward of the head 66. After the forward movement of the ram 62 has stopped in its driven position as a result of loss of energy from driving the fastener and the buffering action of the compressed gas pocket the compressed gas acts upon the ram head 66 to drive the ram rearwardly in the direction of arrows A, as shown in FIG. 7. The ram 62 is thus driven back toward its driving position with sufficient force to cause it to strike the piston 38 and return the latter to its driving position. As the ram 62 approaches its driving position, the ring 76 encounters the chamfer 74 and is forced to contract radially whereupon the ring 76 enters the groove 75 and snaps radially outwardly to its original radial dimensions and into engagement with the groove 76. Thus the ram 62 and piston 38 are returned from their respective driven positions by combustion gases and retained in the said driving positions against accidental displacement until the tool is again fired. The return movement of the ram head 66 from its driven position uncovers the port 48 to permit the combustion gases to be vented to the atmosphere by way of the vent 39.
The tool structure of this invention thus provides for a relatively simple means for utilizing combustion gas pressure to both drive a ram through its work stroke and through its return stroke. The system also provides for releasably retaining the ram in its driving position so as to provide for substantially constant power output for the tool with a given propellant charge. The invention can be used with either cased or caseless propellant charges.
Since many changes and variations of the disclosed embodiment of the invention may be made without departing from the inventive concept, it is not intended to limit the invention otherwise than as required by the appended claims.
What is claimed is:
l. A power actuated tool comprising:
a. a barrel;
b. annular means mounted in said barrel-to provide a bore;
c. ram means mounted in said bore and moveable therein between a rearward driving position and a forward driven position;
d. chamber means rearward of said ram means to receive an expanding volume of gas;
e. gas passage means extending between said chamber means and a forward area of said bore, said gas passage means including firstport means opening into said chamber means, and second port means opening into said forward area of said bore;
f. piston means mounted in said chamber means and movable therein between a rearward driving position and a forward driven position, said piston means being movable independently of said ram means, and said piston means being movable against said ram means to propel the latter from its driving position to its driven position;
g. said gas passage means being operative to transfer a quantity of expanding gas from said chamber means to said forward area of said bore to provide a gas spring in said forward area of said bore operative to return said ram means from its driven position to its driving position;
h. means in said barrel operative to releasably retain said ram means in its driving position; and
i. means in said chamber means for venting gas therefrom when said piston means is in its driven position.
2. A power actuated tool comprising:
a. a barrel;
b. annular insert means mounted in said barrel, said insert means having a bore for receiving an expanding volume of gas;
0. annular sleeve means mounted in said barrel forward of said insert means, said sleeve means having a bore;
(1. piston means mounted in said insert means bore for movement between a rearward driving position and a forward driven position;
e. ram means mounted in said sleeve means bore for movement between a rearward driving position and a forward driven position, said ram means being movable independently of said piston means, and said ram means abutting said piston means when both are in their respective driving positions;
f. means forming a gas passage extending between said insert means bore and said sleeve means bore, said gas passage including a first port opening into said insert means bore, and a second port opening into a forward area of said sleeve means bore, said gas passage being operative to transfer a quantity of expanding gas from said insert means bore to 'said forward area of said sleeve means bore to provide a gas spring in said sleeve means bore to return said ram means from its driven position to its driving position;
g. means mounted on said barrel and operative to engage said ram means to releasably hold said rammeans in its firing position;
h. said piston means being operative, when in its driving position, to seal said first port against entry by expanding gases, and said piston means being further operative, when in its driven position, to open said first port to entry by expanding gases; and
i. vent means opening from said insert means bore for exhausting excess gases from said insert means bore to the ambient atmosphere when said piston means is in its driven position.