US2917808A

US2917808A - Swage rifling tool

Info

Publication number: US2917808A
Application number: US448042A
Authority: US
Inventors: Gerald R Douglas
Original assignee: Individual
Current assignee: Individual
Priority date: 1954-08-05
Filing date: 1954-08-05
Publication date: 1959-12-22
Anticipated expiration: 1976-12-22

Description

De@ z2, 1959 Filed Aug. 5, 1954 G. R. DOUGLAS 2,917,808

SWAGE RIFLING TOOL 5 Sheets-Sheet 1 INVENTOR.

i BY GERA Lo l? Daf/ams Dec. 22, 1959 G. R. DOUGLAS swAGE RIFLING Toor.

3 Sheets-Sheet 2 Filed Aug. 5, 1954 JNVENTOR. GfK/Lo Doa/GLAS BY wif/1W Dec. 22, 1959 G. R. DOUGLAS 2,917,808

swAGE RIFLING Toor.

Filed Aug. 5, 1954 3 SheelLs--Sheefl 3 INVENTOR. BYGs/PALD A. Douma/7.5

Unite My invention relates to a method of and apparatus for rifling bored gun barrel blanks by plastic deformation of the metal. More specifically my invention relates to a new concept in swage riing whereby through the use of a swage tool of my unique design, excessive friction and strains which result in galling are overcome without the addition of any lubricating means except a number of drops of an extreme pressure lubricant. Further, by my invention precise control of the pitch of the rifling is made possible since the barrel blank is rotated about a non-rotating swage tool during the swaging operation. A tungsten carbide swage tool is used in my invention and the riding produced thereby has proved to be of unexpected and unpredictable superiority, these high results being obtained by a single pass of the swage tool with no further treatment of substance being required.

For some time now, efforts have been made to perfect' a swage rilling method. In a British patent of 1876 to Nobel, No. 11,346, is disclosed perhaps one of the earliest techniques wherein a riding projectile was shot through a barrel to form an extended grooved counterpart of the riiling of the projectile. Since this early concept, a number of attempts have been made to overcome the extreme friction and galling problem and the diicult problem of forcing the swage tool through the bore of the barrel blank to produce the desired filling. Examples of the attempts made toward this end are shown in the German Voigt patent of 1920, No. 356,817; the U.S. Hatcher patent of 1931, No. 1,789,308; the Australian Holmes patent of 1944, No. 118,255; the U.S. Walker patent of 1945, No. 2,383,356; and the U.S. Sampson patent of 1953, No. 2,641,822.

The late patents to Walker and Sampson mentioned above are directed to the problem of moving the swage tool through the bore to produce rifling conforming to conventional standards without yaw, chatter, or galling. Walker adds a metal plating for a lubricant, and Sampson prefers to do likewise plus accomplishing the swaging operation in two stages.

By my invention the swaging operation is completed in one stage and no complicated lubricating step such as the bore plating with an anti-friction metal is required. Preferably my swage tool has a piston-like pilot, an intermediate portion which forms a lubricant reservoir with the wall of the bore, and a forwardly tapered swage portion which accomplishes the riiiing operation. The pilot is preferably at the forward end of the swage tool. The forwardly tapered swage portion has a conical Huid lubricant trapping section and a cylindrical swaging section. l have discovered that by trapping the lubricant in suitable tine markings in the bore wall, such as normal reamer marks, many, many threads of lubricant are available for the actual swaging operation. I have further discovered that excellent results are obtainedwhen the longitudinal length of the swage section and its inherent bite are minimized. The swage tool States Patent O ICC may then be held in non-rotative condition and the barrel rotated therearound to produce precisely the pitch desired.

It will be appreciated that the exact dimensions of my swage tool are coordinated with the elastic limit, tensile strength, and ductility of the barrel blank. Since deformation of the swage tool is negligible, the dimensions thereof will include a compensation factor which will allow for the springback or recovery of the metal of the barrel blank after passage of the swage tool` through the bore.

In practicing my invention I am able to use the same swage tool for a number of riding twists in rifles of the same caliber. This is uiniquely accomplished by an interconnection of the swage pushing means with a barrel blank turning means which may be adjusted to rotate the barrel blank at varying rates in accordance with the pitch desired. However, for a series of calibers, it is necessary to use a series of push rods which actually force the swage tool through the bore and a series of push rod guides which maintain proper alignment of the push rod with the bore.

The design of my machine takes into consideration the tremendous torque produced as the swage tool is forced through the bore by having the lever arm to the barrel rotating means longer than the lever arm to the push rod.

It will be readily appreciated that various other structural designs may be employed to accomplish this end and that obvious designs for multiple balanced operations will present themselves. j

A rie taken from my production line has achieved a new world record of accuracy of performance on a` target, oflicially certified, the record consisting of the performance in registered competition in which 10 consecutive shots with a .22 caliber center iire rifle were` placed in a group size of .5276 at 200 yards. The rifling of a production line rifle barrel of my invention receives no further treatment of any kind after the one pass swaging operation of the instant invention. The barrel used in establishing the above record received no special treatment.

Other important objects and advantageous features of my invention will be apparent from the following description and accompanying drawings, wherein, for purposes of illustration herein, a specific embodiment of my invention is set forth in detail, and wherein: i

Fig. l is a side elevation of the swage tool of my invention with the important small dimensional` varia-` tions enlarged for clarity;

Fig. 2 is an end view of Fig. 1 with dimensional varia-` tions enlarged for clarity;

Fig. 3 is a side elevation of the swage tool in a bored barrel blank which is shown in section with normal` reamer marks enlarged for clarity in the bore and tool dimensional variations enlarged for clarity;

Fig. 4 is a greatly enlarged view of the portion of Fig. 3 within the dotted line rectangle 4-4 showing the trapping of lubricant in the enlarged reamer marks;

Fig. 5 is a side elevation of the machine of my in- Ventron;

Fig. 6 is a plan View taken on line 6 6 of Fig. 5" showing a portion of the gear train;

Fig. 7 is an enlarged sectional View taken on line 7-7 of Fig. 5; and l j Fig. 8 is an enlarged side view partly in section showing the means for holding the rearward end of the barrel ,i bunk in the Spindle chuck ofthe head stock.

The swage tool 14 of my invention, which is shown in `Figs. l-4, preferably includes at its forward end a plston-like pilot 15, an intermediate portion. 1,6rear-tliy wardly of and of less diameter than the pilot, a forwardly tapered swage portion 17 rearwardly of the intermediate portion, and a rearward cylindrical end 18.

. The pilot 15 is tapered at its forward end to facilitate insertion into the bore 21 of a barrel blank 19 and the diameter of the pilot is .001 inch less than the diameter of the bore to facilitate the guiding of the swage tool without detrimental yawing or chattering thereof. The pilot is approximately 40 percent of the length of the swage tool and is highly polished.

The cylindrical intermediate portion 16, which is approximately 30 percent of the length of the swage tool 1g4, has a diameter of .O20-.040 inch less than the bore 21 to form with the wall of the bore an annular reservoir 20 for a uid lubricant remaining after passage of the pilot 15.

The forwardly tapered swage portion 17 is made up of a conical iiuid lubricant trapping section 22 and a cylindrical swage section 23. The cylindrical swage section 23 hasa number of equally spaced helicoidal grooveforming runners 24 and land-forming grooves 25 which are .002 to .005 inch deep depending on the caliber of the barrel with an allowance made for spring-back and the like.` In the embodiment shown there are six equally spaced grooves 25, the side walls of each groove forming an angle of 70 degrees. The transverse peripheral dimension of the arcuate surface of each of the runners 24 is about 21/2 times the outer transverse peripheral dimension of each of the grooves 25. The runners 24 have a radius which forms the finished riiling groove in the barrel4V blank with an allowance for spring-back of the barrel metal, and the grooves 24 have a radius to their bottoms equal to the desired bore diameter of the ritle barrel plus the spring-back allowance. Through experimentation, I have discovered that for all calibers from .22 to .30 the longitudinal length of the cylindrical swage section 23 is preferably .050 to .O90 inch. This, percent` agewise, is substantially l percent of the length of the swage tool 14. The conical lubricant trapping section 22 is preferably l5 percent of the length of the swage tool. T he forwardly tapered swage portion 17 is very highly polished to produce an ultimate surface finish and an infinite blend of the conical lubricant trapping section 22 with the cylindrical swage section 23 whereby disernment of the two

sections

22 and 23 is impossible. As seen in Fig. 1, the swage section grooves 25 extend a slight amount into the lubricant trapping section 22.

The rearward cylindrical end 18, which is about 5- percent of the length of the swage tool 14, has a diameter of 0.002 inch less than the bore 21. I have discovered that the rear edges of the runners 24 do not fracture, even under the most extreme conditions, by this design. A spherical seat 26 is formed in the face of the rearward end 18, the diameter thereof being approximately 70 percent of the diameter of the bore.

I` have discovered that unexpectedly and unpredicably superior results may be attained through the use of a swage tool in accordance with the above-described design. Further, I have discovered that the ultimate of results is obtained by the use of a swage tool of tungsten carbide. In my tungsten carbide swage tool, the grooves 25 are preferably ground in at the desired angle; the wall of' the pilot 15 is highly polished by the use of 8,000 grit diamond; and the lubricant trapping section 22 and the swage section 23 may be similarly polished but to a much higher iinish. Actual use has shown that a swage tool manufactured and polished in this fashion has a long life and when properly used with a suitable lubricant completely eliminates all galling problems and nulliiies any tendency of the swage tool to yaw or chatter in the barrel blank bore.

As seen in Fig. 3, a swage tool 14 is inserted in a barrel blank 19 and pushed therethrough by means of a hardened, ground and polished push rod 27 which is preferably about 36 inches long and has a diameter of aart/,see

approximately .004 inch less than the bore of the barrel blank 19. The bore 21 of the barrel blank, as shown in Fig. 3 and enlarged in Fig. 4, has a series of irregularities or normal reamer marks 28 on the Wall thereof which have been greatly enlarged for clarity and which are estimated as having a depth of approximately .0005 inch. The extremely fine tool marks 28 are substantially spiral and continuous in nature. The pilot 15 contacts the outer peripheral edges of some of these tool marks and thereby guides the swage tool centrally through the bore in the barrel blank. Fluid lubricant remaining after the passage of the pilot 15 is present in the annular lubricant reservoir 20 and a portion of this lubricant is then trapped in the valleys 29 of the tool marks 28 by the extremely highly polished conical trapping section 22 of the swage portion 17. These extremely small, substantially spiral-segment threads 30 of suitable lubricating material provide the necessary lubrication for the swage section 23 as it passes through the bore 21 and causes the metal of the barrel blank to conform with the` runners and grooves of the swage section by plastic de-v formation. The tool marks 28 covering the grooves 25 of the swage portion 17 provide a reservoir of threadsof lubricating material which further insure proper lubricaf tion of the swage section 23 throughout its entire length. All dimensions of both the barrel blank 19 and the swage-v portion 17 are carefully determined such that the metal displaced by the runners 24 of the swage portion. 17 is'forced to flow into the grooves 25 where it is swaged by the bottom walls of the grooves 25 to form the exftremely smooth rie lands required in accordance with the conventional linished standard. The length of the' swage section is of a predetermined minimum dimen'.-l

sion, preferably .050 to .090 for all calibers from .22 to. 30, to minimize the bite of the runners 24 and thereby minimize the inherent rotative tendency of the swage.

tool on movement through the bore while at the same` time providing rifling in the bore which will conform to the conventional finished standard without further treatment of any kind.

The overall length of the swage tool is preferably 16 to 7A; inch for all calibers.

As willl be explained hereinafter, the push rod 27 is moved'with great force into face-to-face abutting frictional engagement with the spherical seat 26 of the rearward endv 18 of the swage tool 14. The force is tremendous and the frictional engagement between the swage tool seat 26 and the spherical ended push rod 27 is suicient to over-- come completely the minimized inherent rotative tendency of the swage tool whereby during travel of the swage tool through the bore of the barrel blank 19 no rotation occurs. The desired pitch of the rifling is accomplished,

through the precise rotation of the barrel blank by means to be described. This feature makes it unnecessary'toy employ, more than one swage tool for a given rifle caliber,

as all riing of various twists normally used can be made. with one swage tool, due to the short bite of the runnersi 24 of the swage tool in the barrel blank metal. In practice it has been found that the varied pitch rifling produced by rotation of the barrel blank at various speeds has been` extremely satisfactory and well above the conventional finished standard.

in Figs. 5-8. Referring now to Fig. 5 it will be seen that' a base frame 31 supports a head stock 32 in which the barrel blank 19 is mounted within a spindle 33 which is in turn held in a spindle chuck 34. Aligned with; the; boredbarrel blank 19 is a push rod guide 35 which, as.-

seen in Fig. 7, has an-open top keyhole slot 36 in which is slidably mounted the push rod 27, the longitudinal cerrtral axis of the push rod 27 being a perfectly aligned ex-Y tension of the longitudinal central axis in the bore of theV barrel blank 19. The enlarged circular portion 37 of the 5. keyhole slot 36 is of a diameter equal to the bore of the barrel blank and provides substantially the same clearance for the push rod 27 as exists within the bore of the barrel blank. The parallel walled portion 38 of the keyhole slot 36 has a width of approximately 75 percent of the enlarged circular portion of the keyhole slot.

As seen in Figs. and 7 one end of the transverse member 39 is a swage tool pushing end 42 which extends transversely into the keyhole slot 36 and has a spherical seat 40in its forward face which receives the rear spherical end 41 of the push rod 27, this frictional, face-to-face abutting engagement being similar to that previously described between the forward end of the push rod and the swage tool and capable of completely overcoming any rotative tendency of the swage tool and push rod.

The transverse member 39 is rigidly mounted to a ram 43 of a hydraulic cylinder 44, the hydraulic cylinder being supplied with the necessary hydraulic uid power by suitable pump and control means not shown. The other end of the transverse member 39, which is the barrel blank rotating end 45, is bolted to a drive bar 46 of considerable length which is supported in a suitable rearward guide 47 and forward guide 48. At the forward end of the drive bar as shown in Fig. 6, there is a rack 49 which is arranged operatively to engage a change gear 50 of the gear train which rotates the barre] blank in the required predetermined fashion to produce the desired rifiing. As seen in Figs. 5 and 6, the gear train includes the change gear 50, and idler gear 51 affixed to and above the change gear 50 which turns a vertical shaft gear 52, the vertical shaft 53 and the miter gear 54, the miter gear 54 turning a second miter gear 55, a horizontal shaft 56, and an idler 57, the idler 57 then turning the spindle gear 58 which rotates the spindle 33. The barrel blank 19 is rigidly held in the spindle 33 by means of a split collet 59 in the spindle chuck 34 and a standard 3-jaw universal chuck 60. As seen in Fig. 6 the bottom change gear 50 and its top idler gear 51 are mounted on a swinging arm 61. The arm 61 has an arcuate slot 62 therein whereby suitable swinging adjustment through handle 64 about the vertical shaft 53 is allowed for substitution of the change gear 50 when a different rie pitch is desired. A lock nut 63 secures the arm 61 in the desired position.

It will be noted in Fig. 5 that the distance from the ram 43 to drive bar 46 is about twice as much as the distance from the ram 43 to the push rod 27, this 2 to 1 lever arm ratio tending to equalize the torques involved.

As seen in Fig. 8 the barrel blank 19 is turned to a predetermined outside diameter larger than the desired iinished ritied barrel and has an integral collar 65 on the rearward end portion which abuts the split collet 59 in the spindle chuck 34, the spindle chuck having a tapered hole which receives the tapered shoulders on the collet to align the barrel blank with the push rod 27 whereby the longitudinal central axis of the bore of the barrel blank is aligned with the longitudinal central axis of the push rod 27. As previously mentioned, the other or forward end of the barrel blank 19 is held in standard 3-jaw universal chuck 60 which maintains the alignment.

In the production of ritling in a previously turned barrel blank having an annular shoulder at one end and a reamed bore therethrough, a suitable lubricant is deposited in the bore. In practice it has been found that merely pouring 8 to 10 drops of automotive gear lubricant such as: (Pennzoil Gear Lubricant No. 612 or 614 S.A.E. No.-9) into the forward end of the bore gives excellent results. The swage tool 14 is then inserted into the forward end of the bore with the pilot 15 forward. The barrel blank and swage tool assembly is then inserted through the spindle chuck 34 and the split collet 59 placed around the barrel blank with the collar 65 of the barrel blank 14 resting against the face of the split collet. The angular shoulder on the collet 59 centers the barrel blank with the push rod 27 and the 3-jaw universal chuck 60 6 may then be tightened up thus holding the barrel blank in proper position in the spindle 33.

The push rod 27 is then moved forward by activation of the hydraulic cylinder 44 which moves ram 43 and transverse member 39, the push rod 27 being forced into face-to-face frictional engagement at its forward spherical end with the spherical seat 26 at the rearward end 18 of the swage tool. Further hydraulic power applied to the hydraulic cylinder 44 causes the push rod 27 to move the swage tool through the barrel blank 19, no rotation of the swage tool occurring since the bite of the runners 24 of the swage tool is at a minimum and the abutting frictional engagement of the push rod 27 with the swage tool spherical seat 26 and the spherical seat 40 of the transverse member 39 is sufficient to overcome the remaining inherent rotative tendency of the swage tool. As the transverse member 39 moves forwardly during the riing operation, the other end or barrel blank rotating end 45 thereof moves the drive bar 46, thereby causing the rack 49 to rotate the change gear 5l) and through the gear train thereby impart rotary motion to the barrel blank 19. The precise, predetermined rotary motion of the barrel blank in relation to the forward motion of the swage tool is thus achieved, thereby producing a rilled barrel having a precisely accurate rifling twist. This swaging operation is a very fast procedure, taking a period of time of substantially a minute or less.

I claim:

1. A swage tool of tungsten carbide for forming helica1- like rilling in a bored barrel blank comprising a pistonlike pilot of a diameter slightly less than the bore of said blank, an intermediate portion rearwardly of said pilot and of a diameter less than said pilot, and a forwardly tapered swage portion rearwardly of said intermediate portion with helicoidal groove-forming runners thereon, said runners being of a predetermined radius to produce rifling conforming to the conventional iinished standard and said runners being of predetermined minimum length to substantially eliminate the inherent rotative tendency of the swage tool on movement through the bore of said blank so that the helix may be created by rotation of the barrel blank without rotation of the swage tool, said intermediate portion forming an annular space with the wall of the bore which traps a fluid lubricant to insure lubrication of said forwardly tapered swage portion.

2. A swage tool for forming helical-like riing in a bored barrel blank comprising a portion having a diameter less than the bore of the blank for guiding the swage tool, and a forwardly tapered swage portion having helicoidal groove-forming runners thereon, said runners being of a predetermined radius to produce riding conforming to the conventional finished standard and said runners being of a predetermined minimum length to substantially eliminate the inherent rotative tendency of the swage tool on movement through the bore of the blank so that the helix may be created by rotation of the barrel blank without rotation of the swage tool.

3. A swage tool in accordance with claim 2 wherein said swage tool is of tungsten carbide and wherein said forwardly tapered swage portion includes a cylindrical swage section in which said helicoidal groove-forming runners are formed, said cylindrical swage section being of a length within the range of .050 to .090 inch.

4. A swage tool of tungsten carbide for forming helicallike rifling in a bored barrel blank comprising a portion having a diameter slightly less than the bore of the blank for guiding the swage tool through the bore without yaw or chatter, and a forwardly tapered swage portion having a conical fluid lubricant trapping section and a cylindrical swage section rearwardly thereof, said swage section having helicoidal groove-forming runners thereon, the

References Cited in the le of this patent UNITED STATES PATENTS Castle `uly 28', 1908 Vogt Feb. 4, 1913 Hatcher J an. 20,- 1931 Multhaupt Aug. 181, 1931 Walker Aug. 2'1, 1945 Lee Mal'.v 15, 1949 Sampson June`1'6, 1953 UNTTED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION December 2.2, 1959 'Patent No Q ,9317 808 Gerald R., Douglas It is herebjr certified that error appears in the -printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, line Mw hfor "disernment" read e disoexctnmerlJr m; column 4, line 35, for "30" reed fm 3D me Signed end sealed thier SHQ-th dey o' Mey 1960.,

(SEAL) Attest:

KARL iii, AXLTNE ROBERT C. WATSON Commissioner of Patents Attesting Oficer