US2415300A

US2415300A - Machine for rifling gun barrels

Info

Publication number: US2415300A
Application number: US498186A
Authority: US
Inventors: John E Lovely
Original assignee: Usa
Current assignee: US Government
Priority date: 1943-08-11
Filing date: 1943-08-11
Publication date: 1947-02-04
Anticipated expiration: 1964-02-04

Description

Feb. 4, 1947. J. E. LOVELY MACHINE FOR RIFL ING GUN BARRELS Filed Aug. 11, 1943 4 Sheets-Sheet 1 45% ZZI/WZZ/ Feb. 4, 1947. J. E. LOVELY MACHINE FOR RIFLING GUN BARRELS 4 Sheet s-s 2 iled Aug. 11, 1943 g k a Febo 4, Q J E. MACHINE FOR'RIFLING GUN BARRELS Filed Aug. 11, 1943 4 Sheets-Sheet 3 lzi/rz M 0 4 Shets-Sheet 4 Filed Aug. 11, 1945 Feb. 4, 1947.

1 4 x W m E m/a/wk E Patented Feb. 4, 1947 MACHINE FOR RIFLING GUN BARRELS John E. Lovely, Springfield, Vt., assignor, by mesne assignments, to United Statesv of America 'ApplicationAugust 11, 1943, Serial No. 498,186

(or. 90-2s.1)

12 Claims.

rifling the bore of gun barrels.

It is the principal object of my invention to provide a machine for riflingthe bore of a gun barrel having a bore which may vary in form or diameter such as a taper bore gun.

In recent years, high velocity gun development has resulted in the. design of a gun barrel having a bore including ataper portion to reduce the diameter of the bore from a greater diameter adjacent to the chamber of the gun to a lesser diameter at the muzzle end of the gun. The projectiles to be fired in a gun of this type are known as deformable projectiles and are provided with fins or the like to fit the bore of the gun at its greater diameter adjacent to the firing chamber.

These fins present a large area to the expanding gas pressure from the exploding charge in the firing chamber but during the passage of the projectile through the taper in the bore, they are folded back or deformed resulting in a projectile of a reduced size diameter commensurate with the smaller diameter of the taper bore at its muzzle end. Thus the projectile ofcomparatively small cross section has imparted thereto a high muzzle Velocity due to the initial large area ex-- posed to the expanding gas pressure. The taper portions of the bores of gun barrels of this type have assumed various forms in development and may or may not be rifled. It is believed advantageous to rifle the taper portion of the bore and so far as I am aware, no successful rifling machines have heretofore been designed or produced which could rifle the taper portion of the bore in a manner. satisfactory for economical production.

It is, therefore, an important object of my invention to provide a method and apparatu for rifling any or all portions of the bore of a gun barrel having a taper portion in the bore, which method and apparatus will speedily and economically produce-the desired results satisfactorily from the point of view of mass production 22:1

The method of my invention requires that the gun barrel be held in a-stationary position'while a cutter or broach assembly is moved in a spiral path through the bore of the gun in cutting relation with the surface of the bore to thereby machine a rifle groove having the required twist or number -of turns. The cutter is giventhe spiral path and is maintained in accurate cutting relation with the vbore by means of a cylindrical bar having a profile corresponding in form to the bore of the gun which may include a portion of varied form or diameter such as a taper. The cylindrical bar, which I term a rifling bar, is

' quired depth.

provided with a spiral groove in which the cutter or broach assembly is moved and the groove is of a uniform depth which will maintain the cutter during its spiral path through the tapered bore in the desired cutting relation so that a cut of uniform depth will'bemade. This cutting relation is maintained the same during theentire passage of the cutter or broach assembly through the bore, V

It is an object of my invention to provide a rifling machine having means to supporta gun barrel in a stationary position during the machining of a rifle groove together with means for rotating the barrel and indexingthe barrel to a new stationary position for machining the succeeding rifling grooves.

It may be necessary, that the cutter or broach assembly be passed through. the bore several times in a cutting relation to the surface of the bore in order to produce a rifle groove of the re- It is afurther object, therefore, ofmy invention to provide a cutter or broach assembly adapted to be passed through a spiral path in cutting relation to a gun bore of varying form or diameter and having means to adjust the cutter after each passag through the bore to efiect an increase in the depth of cut or to withdraw the cutter from cutting relation with the bore. 7

It is also an object of my invention to provide a cutter or broach assembly as described above which is equipped-with two cutters faced in 0ppcsite directions and which may be alternately engaged in cutting relationwith the bore so that a cut may be effected by travel of the broach in each direction through the bore.

Further objects and advantages of my inven tion will be apparent by reference to the following specification and drawings in which Figure l is a side elevation of the complete rifling machine of my invention showing a gun barrel in position for rifiing.

Figure 2 is a plan view of machine shown in Figure l.

Figure 3 is a plan view of the rifiing bar showing the spiral groove in the surface of the bar.

Figure 4 is a detail sectional view on line 4-4 of Figure 1. l Figures 5 and 6 are detail sectional views on lines 55 and 6-45, respectively, of Figure3.

Figure 7 is a longitudinal section of a portion of the rifling bar and showing a single cutter broach assembly in longitudinal section slidably Ill-l of Figure 7.

Figure 11 is a detail sectional view on line Figure 8 is similar to a portion of Figure '7, but showing the position of the cutter on the return stroke.

Figure 9 is a fragmentary view similar to a portion of Figures 7 and 8 but showing the relative positions of the parts in which the cutter can be .ren ovedor replaced. m

Figure; 10

is "a detail sectio at. vie 11- m l|--ll of Figure 9.

Figure 12 is an exploded perspective 'viewcf certain parts of the cutting breach assemb1y.: Figure 13 is an enlarged detaillongitudinal sectional view taken on line l3"|'3 of Figure 1, showing the cutting adjusting mechanism in position on the machine at the'end of the'rifiing 4 i in response to the piston rod I without moving the cable I5, thus protecting the cable against breakage and insuring the safety of the operator of the machine.

Still referring to Figures 1 and 2 of the drawings, the heads 20 and 2| are supported on the bedlails ,of,. the machine, and arefixed by. set screws 'i orfboltsin the! semi-permanent positions as shown; Rotatively 'journ'aled in the heads 20 and2l are the gun barrel receiving spindles 22 and 23. Figure 15 of the drawings is a secti'onal view to a larger scale clearly showin the head and spindle 22 and the method of securing, the spindle within the head by means ofthe threaded ring ornut 24. The spindle 23 is similarly retained in its head 2| by means of threadedring-25; Bolted to the spindles 22 and bar support adjacent to the breech end. of the un barrel.

Figu re 1.4,is adetail sectional view on line -Figure 19 is an exploded perspective view showing cooperating parts of the cutter adjusting melchanismland .thecutter assembly at one end of the cutter bar.

Referring to Figures 1 and 2'of the drawings, ,theriflingmachineis comprised of the elongated 'bed fl having onits upper surface the bed rails 12.1andf3. Mounted on one end of the bed I as shown, i's'a, hydraulic cylinder .4 provided with jthe 'cylinder'heads '5 and 6 located at each end ofgthecylinder. Any suitable hydraulic mechanism ,(not shown) comprising pump, valves and .pipingfor distributing fluid under pressure to eaohend of, the cylinder i provided. Slidable through, the cylinderhead 6 is a piston rod I connected to the piston 8 within the cylinder 4.

By selectively supplying fluid under pressure to .eitherendof .the cylinder, the piston and piston rod. will bereciprocated as should be well understood. Straddling the bed rails 2 and 3 and sejcuredfiin, a, relatively fixed position, as shown, are the sheave supportsfi and Ill. Rotatably mountedonthe supports Band 10 are the sheaves or pulleys II and I2, ,fI'he'position of the sheave support Hlmay be adjusted longitudinally of the bedtby means of the screw shaft l3 to which is'keyed the handiwheel I4. Looped around the sheaves Hand 12 is the wire cable 15, the ends of which arejoined together by the turn buckle I6. By adjusting the turn buckle I 6, bradjustinetha posi ion-o th sheave u p n y means of the hand wheel l4, tension of the cable tima iba fisula ed-.

The ireeend cfthe pistonrod 1 is attached to a cable. carriage l'l lidably positioned on the bed rails 2 and 3. It should be apparent that whenthe piston rod 1 is reciprocated, the cable carriage ll will likewise be reciprocated. The cable carriage .l 1 is connected to one side of the flooped cable ji byrneans of the cable bushing t8 and shear pin l9 (see also Figure 4). Should the cable I5. resist movement by a force-beyond a predetermined amount, the shear pin I 9 will break, enabling the cable "carriage I! to move 23 are.v the gun barrel chucks 26 and 21. a gun barrel such as shown by 28 in Figures 1 and 2 ;r nay be passed through the spindles 20 and 21- and chucked in thejaws of the chucks 26 I With the gun barrel positioned through the spindles zil and 2l,-and secured by the chucks 26 and -2l,-it should be evident that the gun barrel Willgbe rot'ativelysupportedover the bed of themachine. To secure the gun barrel against rotation during the cutting operation, an indexing 'a'r'i d'locking'device is provided as shown by Figures land 2 but more clearly shown by Figures 15 and 16. To the spindle 22 is keyed a dial or 7 index plate 29, provided with a series of appropriately spaced radial grooves 30. Pivotally mountedon the bushing 20 is an indexing lever 31 opratively connected to the push rod 32fand having ahandle 33. Compression spring34 normally urges the push rod 32 into engagement.

with 'oneofthe radial grooves 30 of the index plate29 thuslocking the index plate 29 and gun barrel spindle 22, together with'the barrel chuck 26 J and' gun barrel 28, against rotation. By manipulating the handle 33, the gun barrelmay 'be'releasedand' then manually rotated and indexed to the next'station or position for cutting another rifling groove in the barrel. If, for exampl e,the gun barrel is to have twelve rifle groovesthe' index plate 29 will be provided with twelve equally'lspaced radial grooves 30 thusgivihg twelve different and equally spaced starts for, 50

he cuttingitool within the circumference of the bore 'offtlfie gun barrelto' be rifled.

Figures 1 and 2, of the drawings,

arifling bar- 35 is positioned within the bore of the, gun barrel 28. This rifling bar is supported at its ends me supports stand 31 straddling and fixed to the'bed rails 2 and 3. As shownin Figures-'3, Sand e, the rifling bar 35 is cylindrical in cross section and its' profile conforms to the profile of the gun bore. That is to say, the profilof the rifling bar 35 is provided with a taper port-ion38 to conform to the taper portion of the' gun barrel, The diameters of the rifling bar 1 out 'it's'l'ength conform to the diameters of the bare" with the exception that they are .001" to .002" 'under the b'ore size. The rifling' bar does riot, however; conform to the form anddiameter "of"the fifing' 'chamber of the'gun barrel and, 'ftherefore, the maximum diameter of the rifiing 7 bar hould not'be greaterthan .001"-to .002", Q the diameter ofthe major diameter of the 'gi n'bor'ei The rifiing bar 35 is provided with a spifalf groovejil of uniform depth. Said spiral ZQQve geometrically designed to correspond to "the riflingfgfoove to b'e'produced in the gun bore and to havethe required number'of turns."

.. In order to accurately position the rifling bar 35 within the gun barrel 28, so that the taper of the rifiing bar will correspond and be exactly correlated to the taper in the bore, the fOllOWiIlg describedmechanism shown in Figures 1, 3 and 13 i of the drawings is provided. The support 33 in which the breech end of the rifling bar 35 is secured as through a locating pin 350 (Figure 14) and, if desired, by a hinged clamping cap 35|,- is

clamped to the breech end of the gun barrel by means "of the clamp ring 4|]. The clamp ring 40 is bolted to the support 36 by bolts 350 which en- 'gage a ring 4| having a hub 4|0 journaled with respect to the support 36 and the bolts may be adjusted to change the position of the support 36 longitudinally of the bed l'to relatively position the rifling bar 35 longitudinally of the gun barrel 28 and thus accurately aline the taper portion 38 of the rifle bar with the taper portion of the gun barrel.

The apparatus as just described provides for the support of a gun barrel 28 with a rifiing bar 35 accurately positioned within its bore to conform to .001" to .002" under bore size. The cable I is passed through the spiral groove 39 of the rifling bar 35 and is connected to a cutter or broach assembly slidably positioned within the spiral groove. This cutter or broach assembly will be described in detail hereinafter. When the cable [5 is moved in response to the reciprocation of the cable carriage I! and piston rod 1, the cutter or broach assembly will be movedin a spiral path as defined by the spiral groove 39 By adjusting the cutter to a cutting relationwith the bore, a rifle groove will be produced in the gun bore as the broach assembly is pulled through the spiral groove of the rifling bar in respons to the movement of the cable or other flexible wirelike element.

The mechanism for adjustin the cutter or broach assembly into and out of cutting relation with the bore of the gun barrel will now bedescribed, together with details of the broach assembly. i

Referring to Figures 7 to 12, inclusive, a single 71145 cutter broach assembly is shown. Slidably positioned within the spiral groove 39 of the rifling bar 35, the broach assembly is comprised of the tool carrier 42 and the cutting tool 43. The tool with the exception that its vertically extending longitudinal sides are shaped to conform to the shape of the walls of the spiral groove 39 thus enabling the tool carrier 42 to be freely slidable in said spiral groove. The tool carrier 42 is bored to receive a tool adjusting rod 44 which may be moved within predetermined limits relative to the tool carrier 42. The adjusting rod 44 is provided with the cam surface or incline 45 which engages the cutter 43 mounted for longitudinal adjust- -60 ment in a slot 452 through the tool carrier 42, and advances the cutter in and out of the broach assembly in response to therelative movement of said adjusting rod and. tool carrier. The tool adjusting rod 44 is connected with the cable l5 by any suitable threaded couplings such as 46 and 4?,

The relative movement of the tool carrier 42 and tool adjusting rod 44 is confined to predetermined limits by the stops or spacers 48 and 49 which are threaded to the tool adjusting rod. The adjusting rod 44 is also limited in its movement to the left relative to the tool carrier 42 to thus eiTect a withdrawing of the cutting tool 431from a cutting relation by the shoulder 50 abutting the adjustingnut carrier 42 is of approximately rectangular shape the removal ofthe cutting tool 43 for regrinding when the bar is moved to the extreme left position relative to the tool carrier 42 as shown in Figures 9 and 11, permitting a hacked extremity 45| of the tool which normally rides beneath the rod 44 as shown in Figure 10 to pass the rod 44 as shoyvn in Figure 11. To limit the relative movement of the tool adjusting bar 44 to the right to thus effect a cutting relation of the cutter 43 and determine the maximum depth of cut, the shoulder 52 is provided to abut the adjusting nut 53. Springs 54 are positioned as shown engaging friction plugs 540, which, in turn, engage the .inner face of the nut 53 to maintain the adjustingnuts 5| and 53 in their adjusted positions. The adjusting nuts 5| and 53 are provided with splines 55 and 56 which may cooperate with the splinesof a manually operated tool adjusting mechanism to be later described. Figure 7 shows the tool adjusting rod 44 moved to the right relative to the tool carrier 42 within the limit established by the position of the tool adjusting nut 53 and shoulder 52 for extreme depth of cut on the cutting stroke, while Figure 8 shows the tool retracted for the return stroke, the nut 5| engaging the stop shoulder 50. By further retraction of the nut 5|, the rod 44 may be given sufiicient amplitude to present the cut out 15 into registry with the tool iorre moval of the tool as shown inFigures 9 and 11.

Figure 1'7 of the drawings is an enlarged sectional view of a broach assembly similar to that shown and described in connection with Figures 7 and 12, except that it is provided with two outters 43a and 43b provided with oppositely faced cutting edges so that a groove may be cut in a bore by a passage of the broach assembly in either direction of its travel, both forward and reverse. The tool adjusting rod 59 within the tool carrier 60 is provided with the oppositely inclined cam surfaces BI and 62 so that a relative movement of the adjusting rod 59 to the tool carrier 50 will effect a withdrawal from cutting relation of one cutting tool and an application of the other cutting tool into cutting relation with the surface to be cut. This double cutter broach assembly is provided with the same stops, adjustments, and manual cutter adjusting mechanism as described in connection with the assembly shown in Figures 7 to 12 and therefore their descriptions will not be repeated.

In orderto provide for a manual adjustment of the cutter in the breach assembly during the operation of the machine and to indicate the depth of successive cuts, the apparatus shown in detail by Figures 13 and 19 may be employed. Bolted to the end of the rifling bar 33 is the broach or cutter adjusting bracket 63. Rotatively journaled within said bracket is the sleeve 64 having splines 65 adapted to engage the splines 55 of the cutter adjusting nut 53. Keyed to the sleeve 64 is the two-part hand wheel 65; one part having a series of graduations 6! to indicate the amount of rotation of the sleeve 64 and adjusting nut 53 and, therefore, the relative position of the adjusting rod 44 and the depth of cutfor the cutter 43. The other part. of the hand wheel carries suitable actuating handles. The cable I5 passes through the cable bushing 58 secured to the sleeve 64 by the cap 69.

In operating my rifiing machine asdescribed in connection with the cutter or broach assembly of my invention, the adjusting nut 5| is adjusted so that the cutter 43 will not enga ge the surface of the bore in the gun barrel when the cable |5 5|. A slot 15 in the tool adjusting bar 44 permits 7 and the tool adjusting .rod 44 are moved to the of the cutter adjusting sleeve. 64.

'7 zleftcrelative to the -tool 1carrier::42:. i'The' piston rod fl: isthen-actuated to move the cable carriage to the left and, therefore,- move the broach assembly to the left through the spiral groove. 39 of therifling bar from the muzzle to the breech end of the gun barrel. Splines 55 .of the adjust- -ing:nut will then be engaged with the splines 65 The hand wheel 66 is then turned to. rotate the adjusting nut 53 and provide for a'limitation of the move- .mentzof the tool adjusting rod 44 to the right relative to the tool carrier 42 to thus effect the desired depth 'of cut by the cutter 43. Upon the :movement of the cable carriage l1 and cable 15 t-othe right in response to motion of the piston "rod 'Lthe .tool adjusting rod 44 will be moved to effect a'fmovement of the cutter 43 into cutting relation as determined by the setting of the adjusti'ngnut 53. Thus the broach assemblyiwill be moved through the bore with the cutter in a cutting'relation to produce a spiral groove in the bore conforming to the groove in the rifiing bar.

Upon again reversing the direction of travel of the cablexzcarriage l1, adjusting rod 44 will be moved to the left until the shoulder 50 abuts the adjusting nut 5|, withdrawing the cutter 43 from a cutting relation with the bore and thenthebroaching'assembly is drawn back. After the broach has returned to the breech end of the barrel, the hand 'wheel' 66 may be readjusted to provide .f'or'a'n increase in depth of cut, and the cycle'of operation may be repeated until the de sired depth of rifle groove in the bore is obtained. Thereupon the gun barrel may be manually rotated and'indexed to new stations as provided by the index plate 29 previously described and the cycle of operation in cutting a, new rifle groove may be repeated until all the desired ri'i'le grooves in'the barrel are produced. i i Instead of'operating the machine as just described, an alternate procedure as. follows may be employed: After the broaching assembly has made one complete cut through the barrel and has been returned to its starting position, the index locking lever 3| may be manipulated and the'barrel manually rotated to the next index station 'on the'index plate 29 and there locked. 'Thereupon the broach assembly may be moved through" the barrel in cutting relation giving exactly the same depth of cut as previously cut, sincethe cutter adjusting mechanism has not been changed. After each cutting cycle, the barrel is indexed to the next station until all of the rifiing grooves have been out to the depth provided for by the cutter adjustment. Thereafter, the cutter ad"- justment may be changed to give in-creased dep h of cut and the broach assembly passed through the bore in cutting relation for each of the grooves as provided for by indexing the barrel. This cycle of operation is continued until all of the rifle grooves are produced to the required depth; v

Control handles!!! and H in connection with the control rod 12 and limit switches,' one of 55 which is shown" at 13, control the reciprocating movement of the cable carriage l1 and piston rod 1 as is general practice in the machine tool art.

Insome cases it may be found'desirable to employ means for holding the broach assembly against the base of the spiral groove'39 while it is being traversed and means for so doing adjacent to both ends of the broach assembly have been illustrated in' the drawings. Such means comprises a plate E100 extending across a trans- 'verse 'g roove' H O'ln the" outer'fa'ce of memoranrier"=42; and havingend fianges 120 and-"130 riding beneath overlying: flanges 1-40 and 150. The outertop'face of the'plate'lflfl is beveled 5 as at 16 to facilitate insertion of the tool fzcarrier in the bore of the groove. This' plate 100 is pressedoutwardly as by springs 18 positionediin sockets in its inner face and bearing againist the base of the carrier slot 1 l 0 so as to bring-its outer beveled edges I90 into bearing contact withthe interior faceof the gun barrel bore as shown in Figure 18. The overlying carrier flanges Mil-and T50 prevent disassembly of the platewhen the broach assembly is outside of the. gun barrel bore.

When' the double cutter broach 'assembly;.de:- scribed in Figure 17 is employed, it: should the noted that the movement of the cutters into'and out-of cutting relation with the1bore will: bacontrolled by the direction of travel of the-broach assembly through the bore. Because of thez'opipositely inclined cam surfacesfor moyingfithe cutters, only the designated butter for the. par.- ticular direction of travel of the broach assembly-will be maintained in a cutting relation with the bore. The adjustments and stops for con?- trolling the depth of out are the same asdezscribed in connection with a single cutterbroach assembly, except that an additional manual-cutter adjustment assembly (not shown), which may comprise a hand wheel and cutter adjusting sleeve similar to that shown in Figure 13-, may be provided on the rifiing bar support 31 at the muzzle end of the gun barrel to enable an adjustment and'indication of the depth of cut produced during its cutting stroke by the cutter 58. It'should be obvious that when the double cutter broach assembly is used it is'n'ot necessary to adjust the broach assembly to a non-cuttin relation and return it to the starting point in the bore before making the next out since the double cutter broach assembly will make a cut in each direc tion. t: '-'i I" I have described in connection'withmy'invem tion, a rifiing bar having a rifiing groovexofunL 45 form depth extending fromgthe' surface "of 'the rifiing bar whose profile corresponds. to theme.- file'of the bore of a taper boregun orthe like. Thus a desired cutting relation is maintained throughout the passage of the broach'assembly 60 in the rifiing groove of the rifiing bar. Ifrifling grooves of varying depth are desired to be produced in the gun bore, a variation in depth of the groove in the rifiing bar may be employed to obtain this desired cutting relation, and it may 55 also be advantageous under certain circumstances, as when the profile 'of'the rifiing bar departs somewhat from the bore of the gun barrel, to vary the depth of the spiral orhelical groove in the rifiing bar along the length of the helix 60 to obtain either a uniform or a non-uniform depth of cutting or rifiing in the bore surface of the gun barrel, as may be desired.

While I have described the rifiingmachineof my invention in connection with the rifiing of a taper bore gun, it should be understood that my method and apparatus may be employed to rifle the standard 'form of straight bore gun barrels by modifying the profile of the rifling'bar 'to correspond to the profile of the straight bore.

I have shown and described above, a new method and apparatus. for rifiing the bore of gun bar'- rels and what I claim as new and desire to secure by Letters Patent is: r 4 1. Apparatus for riding a gun barrelhaving 75 bore of varying diameter comprising an elongated bed, means to support a gun barrel in a stationary position longitudinally over said bed, means associated with said gun barrel supporting means to permit rotation and indexing of the gun barrel to a plurality of radially spaced stationary positions, means constituting a rifiing bar adapted to extend through the bore of said barrel and be supported at each of its ends on the elongated bed, said rifiing bar having a profile corresponding to the profile of the gun bore, a spiral groove ofpredetermined lead and uniform depth on said rifiing bar, an adjustable broaching assembly slidably positioned in said spiral groove, manual adjusting means associated with an end ofsaid rifiing bar to permit a manual adjustment of said adjustable broach assembly when in position at the end of said spiral groove, and flexible means associated withsaicl spiral groove and broaching assembly to reciprocate said broaching assembly within the spiral groove extending through the gun bore. i

2. Apparatus for rifiing a gun barrel having a bore of varying diameter comprising an elongated bed,-means to support a, gun barrel in a stationary position longitudinally over said bed, means associated with said gun barrel supporting means to permit rotation and indexing of the gun barrel to a plurality of radiallyspaced stationary positions, means constituting a rifiing bar having a profile corresponding to the profile of the gun bore and adapted to extend through thebore of said barrel and be supported ateach of its end on the elongated bed, means to 'longi tudinally positionsaid rifiing bar relative to the barrel and thereby relatively position the profile of said rifiing bar with the profile of the gun bore, said rifiing bar having a spiral groove of predetermined lead and uniform depth in its surface, an adjustable broaching assembly slidably positioned in said spiral groove, manual adjusting means associated with an end of said rifiing bar to permit a manual adjustment of said adjustable broach assembly when in position at the end of said spiral groove, and flexible means associated with said spiral groove and broaching assembly to reciprocatesaid broaching assembly within the spiral groove extending through the gun bore.

3. Apparatus described in claim 1 wherein said manual adjusting mean comprises a rifiing bar support, a sleeverotatably journaled on said support, a hand wheel keyed to one end of said sleeve, splines extending from the other end of said sleeve, said spline-s adapted to engage and cooperate with the adjusting means of said adjustable broach assemblywhen said broach assembly is in position at the end of said spiral groove, whereby an adjustment of the broach assembly may be made by a rotation of said hand wheel.

4. An adjustable rifiing broach comprising a tool carrier, a cutting tool carried by said tool carrier-and adapted to be moved into and out of a cutting relation, a tool adjusting rod passing through said tool carrier andadapted to bemoved relative to and longitudinally of said tool carrier, a cam surface on said tool adjusting rod, said cam surface engaging said cutting tool and adapted to move said cutting tool in response to the relative movement of the tool adjusting rod and tool carrier, and adjustable means to limit the relative movement in either direction of said tool adjusting rod.

5. An adjustable rifiing broach comprising a tool carrier, pair of cutting tools having oppositely faced cutting edges carried by said tool carrier and adapted to be, moved into and out of a cuttingrelation, a tool adjusting rod passing through saidtool carrier and adapted to be moved relative to and longitudinally of said tool carrier, a pair of oppositelyfaced cam surfaceson said tool adjusting rod, said cam surfaces engaging said cutting tool-s and adaptedtomove said cutting tools in response to the relative movement of the tool-adjusting rod and tool carrier, and adjustable means to limit the relative movement in either direction of said tool adjusting rod.

6. Apparatus for producing a rifle groove in a gun barrel comprising means to support a gun barrel in position to be rifled, means adaptedto extend through thebore of said gun barrel and support a broaching assembly for movement in either direction through the gun bore in desired relation to the bore, a broaching assembly'movably positioned on said supporting means and including a cutter element, said broaching assembly provided with means for moving the cutter into and out of cutting relation with said bore, and flexible meansconnected to said out ter' moving means and adapted to move the broaching assembly in either direction through the bore whereby the movement of the cutter will be controlled by the direction of travel.-

7. Apparatusfor producing a rifle groove in a gun barre1 comprising means to support a'gun barrel in position tobe rifled, means adapted to extend through the bore of said gun barrel and support a broaching assembly for movement in either direction through the gun bore-indesired relation to the bore, a, broaching assemblymovably positioned on said supporting means,*a pair of cutting elements in said broaching assembly, one of said cutting elements adapted to be operative during movement of said broaching assembly in one direction through the boreand the other of said cutting elements adapted to be operative during movement of the broaching assembly in the other direction through the bore, a single cutter moving mean-s for both of said cutting elements and adapted to selectively move one or the other of said cutting elements into cutting relation, and flexible means connected to said cutter moving means and adapted to move the broaching assembly in either direction through the bore whereby the direction of travel will control the cutting relation for each of the cutting elements.

8. Apparatus for rifiing a gun barrel having a bore of varying diameter, comprising an elongated bed, means to support a gun barrel in a'stati onary position longitudinally over said bed, means associated with said gun barrel supporting means to permit rotation and indexing of the gun barrel to a plurality of angularly spaced stationary positions, means constituting a rifiing bar adapted to extend through the bore of said barrel and be supported ateach of its ends on the elongated bed, said rifiing bar having aprofile correspond} ing to the profile of the gun bore, a spiral groove of predetermined lead and depth in said rifiing bar, an adjustable broaching assembly slidably positioned in said spiral groove, and flexible means associated with said spiral groove and broaching assembly to reciprocate said broaching assembly within the spirals groove extending through the gun bore, said gun barrel supporting means comprising a pair of heads spaced from one another mounted on said bed, gun barrel receivgun barrel chucking means fastened to said spin- 2,41 asoo 'dle's, and means-associated withtcat least'oneot saidiheads to prevent rotationiof itsgun 'bar-rel spindle at predeterminedangularlyspaced points. M 9 Apparatus for riflingav gun vbarrel having a bore of varying diameter, comprising. an elongated bed, means tosupport a gun barrel ina stationary position longitudinally over said bed, means associated with said gun barrel; supporting means to permit rotation and indexing'of the gun barrel .to a plurality. ;of angularly spaced stationary positions, means constitutingsja'rifiingbar adapted to extend through the bore of said barrel and be supported at, each of its ends on the elongated bed, said rifling bar-havinga profile;corresponding to the profile of the gun bore, a spiral groove of. predetermined lead anddepth in said rifiing bar, an adjustable breaching assembly slidably positioned in said spiral groove, and flexible means associated with said spiral groove and broaching assembly to reciprocate said broaching assembly within the spiral groove extending through the. gun bore, said flexible means comprising a cable movable in said spiral groove and connected to said broach assembly, a cable carriage slidably mounted on said elongated bed and connected to said cable, and means for reciproeating said cable carriage.

10. Apparatus for rifling a gun barrel having a V bore of varying diameter, comprising an elongated bed, means to support a gun barrel in a stationary positionlongitudinally over said bed, meansassociated with said gun barrel supporting means topermit rotation and indexing of the gun barrel to a pluralityof angularly spaced stationary positions, means constituting a rifiing bar having a profile corresponding to the profile of the gun bore and adapted to extend through the bore of said barrel and be supported at each of its ends on the elongated bed, means to longitudinally position said rifiing bar relative to the barrel and thereby relatively position theprofile of said rifiing bar with the profile of the gun bore, a spiral groove of predetermined lead and depth in said rifiing bar, an adjustable broaching assembly slidably positioned in said spiral groove, and flexible means associated with said spiral groove and broaching assembly to reciprocate said broaching assembly within the spiral groove extending through the gunbore, said longitudinal positioning means for said rifling bar comprising a rifling, barLsupport movably positioned on said elongated bed, a ring clamp adapted to be clamped to the breech end of the gun barreLandmeans to 12 r ve f p dete m ed, ead and d hd said r fl n bar, an adjust ble lb gasbins, ass bly s i ably positioned in said spiral groove; and fieigible means associated with said spiral grooveand broaching' assembly toreciprocate said breaching assembly within; the spiral groove, extending through the gun bore, said broach assembly coin; prisinga tool carrier adapted'to be slidably po;

sitioned in said spiral groove, a cutting tool mounted in said tool carrier and movable into and out of cutting relation to the gun b0re, a.to0l ad; justing rod passing through said tool carrier and movable relative to said tool carrier, said tool ad;- J'usting rod having an inclined surface adapted to engage said cutting toolwhereby a relative movement of said tool adjusting rod and tool carrier will effect a movement of said cuttingtool, and adjustable stop means for limiting the rela tive movement of said tool adjusting rodand tool carrier. j i

12. Apparatus for rifling a gun barrelhavinga borev of varying diameter, comprising an elongated bed, means ,to support a-gun barrel in a stationary position-longitudinally over said bed, means associated with said gun barrel supporting means to permit rotation and indexing of the gun barrel to aplurality of angularly spaced station: ary positions, mean s, constituting a, rifiing bar adapted to extend through the bore of said barrel and be supported at each of'its ends on the elongated bed, said rifiing bar having a profile corresponding to the profile of the gun bore, a spiral groove of predetermined lead and ,depth in said rifling bar, an adjustable broaching assembly slidably positioned in said spiral groove, and flexible means associated Y with said spiral groove and broaching assembly to reciprocate said broaching assembly within the spiral groove extending through the gun b'ore,'said adjustable broach as sembly comprising a toolcarrier adapted to be slidably positioned in said spiral groove, a pair of cutting tools having oppositely faced cutting .edges mounted in; said tool carrier and movable into and out of cutting relation to the gun bore, a tool adjusting rod passing through said tool carrier and movable relative to said tool carrier, said tool adjusting rod having a pair of oppositely inclined surfaces, one of each inclined surfaces gun barrel to a plurality of angularly spaced statio'nary, positions, means constituting a riflin i bar adapted to' extend through thefbore of saidbarrel nd be. supported ateach or, its end on the, elongated bed, said rifling banhavirigb profile "corresponding ,towthe profile of :the. gun jb'ore,' a spiral adapted to engage one of each cutting tools, wherebya relative movement of said tool adjusting rod and tool carrierwill effect a corresponding movement of said cutting, tools, and adjust-v able stop means ionliiniting the relative move} ment of said tool adjusting rod and toolcarrier.

v REFERENCESCITED {The following references ,record in the fileof this patent: o ,1: u, l

UNITED STATES PATENTS P [2 093 18 gmar lie ifs 0.6 --M l -,19 2,256,817 fichneclr Sept. 23, 194-1