US2692383A - Barrel extension assembly for stud drivers - Google Patents

Description

Oct. 26, 1954 R. T. cATLlN BARREL EXTENSION ASSEMBLY FOR STUD DRIVERS Filed Jan. 8, 1954 INVENTOR. ROBERT I CAM/M Vonly light or medium power.

Patented Oct. 26, V1954 BARREL EXTENSION ASSEMBLY FOR STUD DRIVERS Robert T. Catlin, Stratford, Conn., assignor to Remington Arms Company, Inc., Bridgeport,v Conn., a corporation of Delaware Application January 8, 1954, Serial No. 402,901

4 Claims. 1

This invention relates to an accessory for an explosively operated stud driver and more particularly to an accessory which effectively in.- creases the length of the barrel and thereby facilitates the use of slower burning powders de,- sirable for propelling longer and heavier studs.

There are available heavy duty tools which drive long and heavy studs by the use of large centerre cartridges in barrels of length and diameter appropriate to such cartridges but such tools are quite expensive and are of limited use for general-purpose work, most of which requires Some competitive general-purpose tools are provided with interchangeable barrels of varying length and diameter and with chamber inserts receiving special cartridges, but such tools generally require separate handling of stud, cartridge and chamber insert and are otherwise unhandy to use.

With a stud driver of the type shown in Patent No. 2,645,772, issued July 21, 1953, to Merle H. Walker, thev design features which provide for superior performance of the tool, in particular the integral barrel, ejector, and heel cap type ammunition, make it impractical to interchange barrels for increasing capacity.

Ordinarily, extremely fast burning powders are use with these tools to obtain maximum efficiency and to insure that the pressure level is well below peak pressure when the stud reaches the end of the barrel,y with the result that muzzle blast and recoil due to the escape of gas are not excessive. If an attempt is made to increase driving capacity by increasing the weight of the charge of such powders, or by increasing stud weight',y with any given charge, the chamber pressures exceed safe limits, tending to burst cartridge heads and to cause other diiculties. Capacity can be increased without exceeding safe pressure by the use of charges oi powder burning at slower rates, but such charges will still have a relatively high pressure when the stud reaches the muzzle of a standard length barrel and muzzle blast and recoil due to the jet of escaping gas will be unusually severe.

These effects can be shown graphically by plotting; curves of barrel pressure as the ordinate againsttravel of the stud through the barrel as the abscissa and the area beneath the curve is proportional tothe available energy or the capacity of the powder charge for doing work upon the stud. The ordinate of such a curve at a time corresponding to the emergence of the stud from the barrel isinclicative of the recoil and muzzle blast to be expected. With the extremely fast burning powders such a curve is sharply peaked and falls off rapidly to a relatively low pressure', giving minimum blast and recoil when the stud emerges. The pressure operated by the slow burning powders rises relatively slowly to a broad peak and maintains a relatively high level until after a stud emerges from a standard barrel, with the result that blast and recoil due to gas escape are excessive. It is apparent that to drive the longer heavier studs without exceeding safe pressures, it is desirable to use the slow burning powders with relatively greater area beneath a pressure/travel curve, but to reach this end, dangerous pressures, excessive recoil, or excessive muzzle blast cannot be tolerated.

It is the object of this invention to provide a means of driving heavier studs with general.- pu-rpose tools without excessive pressure, recoil, or muzzle blast, and without sacrificing the functional advantages of a general-purpose tool such as that shown in the Walker patent.

I contemplate that these objectives can be accomplished by providing for a standard tool an accessory comprising an extension barrel, a mufiier, and a guard which can be used interchangeably with a standard guard such as that shown in the Walker patent or with the improved guards as shown in the copending applications of Robert T. Catlin, Serial Number 252,949', filed October 24 1951, and issued as U. S. Letters. Patent No. 2,669,716, on February 23, 1954, or Robert T. Catlin and Paul Hickman, Serial Number 300,716, filed July 24, 1952.

With the extension barrel the system remains closed for a longer time and the pressure at the time the stud emerges from the extension is materially lower than with a short barrel; This is in itself enough to materiallyV reduceV theA muzzle blast and recoil, but I find that the effect can be augmented by the venting of the barrel which bleeds off into the mui-lier a substantial fraction of the gas. and still further reduces recoil and muzzle blast. With this system I can take full advantage of the large area beneath the pressure curve, characteristic of slow burning powders, and the great capacity of' such powder for doing work, without exceeding safe pressures or producing excessive recoil and muzzle blast. By surrounding the barrel vents with a muiiler, I minimize the sound of the discharge and safely coniine the jets of flame and possibly particles of unburned power emerging from theI vents. l

The exact nature of the invention as well as other objects and advantages thereof will more fully appear from consideration of the following specification referring to the attached drawing in which:

Fig. 1 is a partial longitudinal quarter sectional view showing a stud driver like that in the Walker patent to which my invention has been applied.

Fig. 2 is a similar view showing the position of the elements of my -device and of the stud driver when held against a work surface in an inclined position.

Fig. 3 is a view similar to Fig. 2, showing the parts in position against a Work surface ready for driving a stud.

Referring to the drawing by characters of reference, it will be seen that I have shown a stud driver comprising a barrel I threadably or otherwise secured at its breech end to a frame plate 2. A breech block 3 is hinged to the frame plate 2 by means of a bolt 4 on which the breech block and frame plate have relative rotation to permit the exposure of the breech end of the barrel. An action tube cover 8 is secured to the frame plate in any convenient way and provides a housing enclosing a portion of the barrel adjacent the frame plate. An action tube 33 is slidably mounted on the portion of the barrel enclosed by the cover 8 and itself encloses an action tube extension spring 31 which acts at one end on a shoulder on the barrel. A finger 32 is mounted on the action tube 33 and is projectable through aligned holes in the frame plate 2 and breech block 3 to operate a sear lock 3| which prevents the firing of the stud driver unless the action tube is retracted upon the barrel into substantial contact with the frame plate 2. The structure described thus far is that shown in Walker Patent No. 2,645,772, to which reference may be made for details of operation. Such reference will be facilitated by the fact that the reference numerals appearing thus far are applied to the same elements as in the patent.

This invention is an accessory for such a stud driver and comprises an action tube extension 36 which is slidable on the barrel I and threadably attached to the action tube 33. The spring 31 acts upon the inner end of the extension 35 and urges it to extend from the housing 8 to the extent permitted by engagement of the action tube 33 with the housing 8, as shown in Fig. 1.

The extension barrel is secured to the action tube extension 36 and is provided with a bore of substantially the same diameter as that in the barrel I. When the action tube extension 36 and action tube 33 are fully retracted with the inner end of the action tube 33 stopped against the frame plate 2, the opposed ends of the barrel I and extension barrel 5 are in contact as at I6 in Fig. 3 and the action tube finger 32 will have released the sear lock 3 I.

The exposed end of the extension barrel 5 is tted with a replaceable, hardened ring 6 which forms a renewable work contacting end on the extension barrel and is provided with a bore 1 through which the stud is projected.

A guard or shield assembly designated generally as 9 is supported on the free end of the extension barrel 5 with capacity for limited longitudinal movement thereon by means of a guard sleeve |Il telescoped over the extension barrel. The extent of movement is limited by several radial pins driven into the extension barrel 5 and engaged in an internal groove I2 in the sleeve Ill, as well as by engagement with the ring 6. In the position shown in Fig. 1, the guard is extended to a maximum and projects or more beyond the 4 end of the disk retainer 6. In Fig. 2 the guard is at its other extreme position, which is that which would be occupied with the extension barrel and guard pressed rmly against a work surface but inclined thereto at about a angle. For details of the construction and operation of the guard assembly, which makes it impossible to re the stud driver when tilted beyond a safe angle, reference may be made to the copending application of Robert T. Catlin or of Robert T.

l Catlin and Paul Hickman, both referred to previously herein.

As in the copending application of Catlin and Hickman, the guard assembly is urged to its posimui-ller or expansion chamber I4 is mounted to enclose the extension barrel 5 and action tube extension 36 with a chamber of substantial volume and being slidable on the extensions serves to apply the reaction of the guard spring I3 to the outer end of the action tube cover 8. Within the muiier, vents I5 penetrate the extension barrel and a row of vents I6 communicate with the inner end face of the extension barrel.

Although the operation of the guard relative to safety control is identical to that in the copending applications of Catlin and of Catlin and Hickman, theneed for reference thereto will be minimized by a brief summary of the operating characteristics. Starting with the Fig. 1 position, it will be seen that the guard assembly and action tube assembly are both fully extendedfand that the finger 32 is remote from the sear lock 3| which must be operated to permit firing of the stud driver. In this position the tool is safe and may not be inadvertently fired.

If, as in Fig. 2, the tool is applied to a work surface, at an angle of other than a side of the guard will rst engage the Work and the guard will be retracted on the extension barrel against the action of the guard spring I3. In an inclined position, the guard sleeve III engages one end of the muier I4 which is in contact with the action tube cover 8 and stops further retraction of the guard. In the limiting position of inclination, the end of the extension barrel will project forwardly from the plane of the end face of the guard and the action tube and nger 32 thereon will not be retracted suiiiciently to operate the sear lock 3|. Fig. 2 illustrates a condition where the stud driver is inclined relative to the work to an extent slightly greater than necessary to prevent firing.

As the tool is brought into a position normal to the work surface, as shown in Fig. 3, the extension barrel is retracted to a position flush with the end face of the guard and the inner end of the extension barrel is brought into contact with the end of the stud driver barrel. In this position the guard sleeve I3 is in engagement with the muiiier I4, which in turn engages the action tube cover 8 and the action tube finger 32 operates upon the sear lock 3| to permit the tool to be fired. This non-tilt feature is common to the copending application of Catlin and Hickman referred to above and to the application of Catlin, Serial Number 252,949, earlier referred to.

Upon firing of the stud driver, there is an inevitable recoil reactionA tending to lift the tool away from the face of the Work. With this design, however, the barrel I of the tool, to which the principal reaction is applied, must recoil for a distance equal to the initial retraction of the action tube 33 before there can be any substantial recoil force acting on the extension barrel 5. Further, the extension barrel must recoil for a distance equal to the retraction of the guard assembly 9 thereon before there can be any substantial recoil force applied to the guard assembly. The guard assembly 9 thus remains in contact with the work surface and effectively protects the tool operator from spalling concrete, metal scale, or other possibly injurious material.

The provision of the vents in the extension barrel relieves the gas pressure causing muzzle blast and tending to cause the barrel of the tool to recoil. The latter effect is particularly important With regard to the vents communicating with the space between the opposed ends of barrel and extension barrel, as at I6 in Fig. 3, in which space gas pressure tending to cause recoil is operating on an area materially greater than the cross-sectional area of the bore of the barrel. At the same time, it may be noted that powder gas pressure action on the extension barrel at I6 tends to hold the extension barrel in closer contact with the Work face, thus further minimizing the chance that tool recoil or the expansion of gas trapped beneath the guard 9 will cause the guard to lift from the Work surface and expose the operator to any escaping material.

Although I have quite specifically described and illustrated only one modification of my in-1 vention, I consider that invention to extend to cover a reasonable range of equivalents and modifications as set forth in the claims appended hereto.

I claim:

1. For use with a powder-actuated stud driver having a barrel through which studs are projected and an action tube for releasing a safety device, said action tube surrounding said barrel and longitudinally slidable thereon between an extended position in which the stud driver may not be fired and a retracted position in which said safety device is released, an accessory device comprising an action tube extension secured to said action tube and slidable therewith on said barrel, and an extension barrel coaxial with and extending from said action tube extension, said extension barrel having a bore of substantially the same diameter as the stud driver barrel, the end face of said extension barrel being in abutment with the muzzle of said stud driver barrel when said action tube and action tube extension are in said retracted position thereon, said extension barrel then serving as a coaxial continuation oi' said stud driver barrel.

2. An accessory device as described in claim 1, said extension barrel being provided with gas vents to relieve gas pressure in the bore thereof.

3. An accessory device as described in claim 2, at least a portion of said gas vents communicating with the end face of said extension barrel in position to relieve gas pressure at the interface between the muzzle of the stud driver barrel and the end of said extension barrel.

4. An accessory device as described in claim 3, including a substantially closed muffler chamber mounted on and surrounding said action tube extension and said extension barrel, said muffler chamber being positioned to receive gases emitted from said pressure relieving vents.

No references cited.

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