US1773741A - Method of making projectiles - Google Patents

Description

Patented Aug. 26, 1930 PATENT OFFICE GILBERT P. McNIIFF, Oli' PTTSBURG'E, PENNSYLVANIA.

METHOD or imma rnmnc'rrtns Application filed p ecember This invention relates to projectiles or explosive shells such as are manufactured in various sizes to be fired from guns of different calibers; and it relates more particu- 5 larly to the manufacture of shell forgings which are loaded with charges of powder,- shrapnel or the like to form the finished projectiles. The latter as ordinarily manufactured com rise a body portion of stream line contour ed with an explosive adapted to be detonated by one--of several detonators or fuses which are usually secured to and close the forward end or nose of the shell forging.

Shell forgings have heretofore beenmanufactured solely by the pierce and draw method in which a solid. billet is pierced inv a closed die by a hydraulic plunger so as to form a rough blank closed at one end. The

0 great dilliculty of machining and finishing a blank of this type results largely from the fact that, one end being closed, it is necessary to do all the inside machining and shaping from the other end of the blank. A

separate machining operation from the bol'- ing of the interior diameter is also required to finish the inside ofthe base and care musty be used to keep the thickness of the base within the required limits. Y

An object of this invention is to provide an improved and simplified method of manufacturing shell forgings,

The manufacture of projectiles by the pierce and draw method requires special-machines, consequently under emergency conditions the capacity of this country t0 produce shell forgings by that method is limited by the capacity of such special machinery as there may then be in existance.

A further object of this invention is to provide a method of making shell forgings capable of being carried to completion by standard machines. Obviously such a method, permitt' an immediate, high production of shell orgings with standard equipment has immeasurable advantages.

The shell produced by the pierce and draw method of manufacture is only about 80% efficient for Vdestructive purposes for the reai son that, upon explosion only about 80% of 7, 1925. Serial No. 73,675.

the body breaks into fragments which are of the destructive size and shape,'viz., the size of a pea orpebble. From'10% to 20% of the shell body is powdered or is broken into such particles that its destructive effect is `greatly diminished; an additional percentlack of a uniform metallic structure throughout the body of a shell and is a necessary result of the pierce and draw method of body formation. A still further object of this invention is to provide a method of maka5 ing shell forgings wherein the metal will be so manipulated as to produce a greater uniformity of structure than has hitherto been attained with the result that the linished shell will have a greater uniformity of fragmentation and consequently a higher destructive eiliciency than has heretofore been possible. A

These and other objects which will appear obvious to those skilled in this particular 'I5 art are accomplished by means of this in- Y vention, certaln steps of which are illustrated in the accompanying drawings, in which Figure 1 is a longitudinal sectionalview of a ltubular blank formed from. metal su .which hasl been so manipulated and worked as to providea highly uniform metallic structure throughout. Figs. 2 to 6, inclusive, are similar views showing the shell blank during dill'erent stages of its manufacture. si Fig. 7 is an end view of the blank illustrated in Fig. 1, and Fig. 8 is a similar view A (if. the partially formed blank shown in 1g. 2. Y The steel from which the blank shown in Fig. 1 is produced is usually in the form of square or rectangular billets. In order to produce a blank having a thoroughly homoeneous structure so as to provlde a very igh uniformity of fragmentation in the 95 completed shell the metal of the billet so worked and manipulated in being'formed, into the hollow blankas to insure a uniformity of metallic structure throughout the blank. Such manipulation of the metal is JA convenient way of piercing the solid bar and at the same time thoroughly working the metal thereof in order to produce homogeneity of structure is to provide a revolving mandrel of substantial length over which the pierced bar is rolled. The piercing'of the bar is done by a blunt nosed, some- 0 what conicallyshaped plug, which isl dropped in front of the mandrel as the bar enters the rolls. The mandrel pushes this plug into the end of the billet as it comes throughthe rolls and holds it there While the rolls force the metal over the plug and along the mandrel. The plug is not directly attached to the, mandrel but floats freely as the tube is beingfformed.V Its engagement with theC mandrel causes it to rotate during the pierc- 301 ing'action-with theresultthat the metal of the billet'is thoroughly worked or kneaded as the rough tubular blank is formed.

' "--In'4 this way. the steel is given a highly homogeneous 'structure throughout, and practically all stratification of the metallic structure is eliminated. The plug being moreor less floating during this step naturally seeks thel center of thebillet and a rough tubular blank having the desired structural char acteristics referred to is formed. If desired, a small hole can be formed in the end of the billet prior to its passage through the rolls so as'to permit the rotating plug to obtain an entering wedge into the billet.

The rough blank thuslformed has a wavy appearance on its exterior" and it is then passed through another set of rolls and over a. common ball mandrel. This operation ysmooths out' the wavy -exteriorof the bla-nk and to a certain extent sizes the interior' thereof. This step is preferably repeated by passing the blank through a third fsetof rolls and over another ball mandrel which constitutes a final sizing ooeration. In each of these last named steps t e metal of the blank is again Worked so as to increase Iits homogeneity of structure. The blank which still has a bright red heat is then slowly cooled until itis black.

The metal of the tubular blank so 4produced has had all stratification of structure eliminated by the thorough working and kneading to which it has been subjected and its structure is found to beiuniform throughout.

It will also be apparent to those skilled inj the art, that the standard machinery employed in the manufacture of seamless tubing has been utilized.

When cool the blank is cut into units so as to form a hollow tubular blank 10, the length of which depends upon the size of projectile being manufactured, and this projectile blank is bored on the inside to provide a finished surface sized to the proper interior diameter, and to eliminate eccentricity. This boring can he performed on a standard machine and no special equipment is required. The bored blank is then heated to a temperature of about 1,800 F. and one end thereof is shaped to rovide a flat closed end 1.1 and this can be one most conveniently by placing the blank in a die of the proper shape and pressing the end thereof so as to form a square based forging. The mandrel is then removed and the blank allowed to cool slowly. This operation forms the tubular blank, which was open lat both ends, into a blank closed at one end having its interior cavity at the closed end the shape of the finished shell or the shape of the finished blank which has hitherto been produced by the pierce and draw method. The interior of the closed base was formerly the side Wallof the hollow blank and hence the single machining operation to which the interior of the blank has been'subjected provides a machined surface for the base of the forging. The operation of closing the end of the blank forces scale and other impurities l2 to the center of the closed end and it is, therefore, necessary to remove these impurities. This is accomplished by drilling or otherwise boring a hole 14 at the center of the base which is preferably conical in shape, having inwardly converging Walls, The other end of the forging is then forged to form a tapered nose 13 by means of a Nazel hammer after which the interior of the tapered nose is bored out to form the cylindrical surfaces 15 and 16. l

As stated, the hole14 in the base is preferably tapered and a conical plug 17 is screwed or otherwise secured in it. The forging is then placed upon a vertical mandrel with the inner end of the plugr resting on the end of the mandrel. While so positioned a press is used forv pressing the plug so that it spreads and completely closes thedrilled hole 14 to insure a rigid connection between the plugl and thebase and a tight lit of the plug in the base.' In view of the fact that the wallsof the tapered opening 14 converge inwardly there is no danger of the plug 17 being loosened when the shell is fired from a gun, as the force of the discharge will tend to drive the plug into a tighter fitting relationship with l the base of the shell.

The forging is finished by cutting threads 18 in the cylindrical surface 15 of the nose; and these are employed in securing a fuse or detonating'device to the projectile. A copper band receiving groove 19 is cut in the outer face of the forging for the purpose of receiving the copper riflmg band.

The metal from which the plug'is made may be the same steel as that from whichthe shell forging is produced, or, if desired, it may be of softer, more'easily flowing metal so as to insure a tight closing of the base 1 when the plug is pressed therein.

The forging may be heat treated at any desired point in the process.

As a result of this method it is possible to produce shell forgings by means of standard machinery in vast quantities with a compara tively few men. All necessity for the special machinery required in the pierce and draw method of manufacture is ellminated and the number of men and time required to produce a given quantity is materially less. In addition to this, the saving in material is substantial.

Due to the thorough working to which the metal of the forging is subjected it possesses physical properties which increase its destructive effect over the shell made by the v pierce and draw method because of its morel homogeneous structure resulting in a greater uniformity of fragmentation upon bursting.

It will be obvious that the sequence of certain of the steps herein described may be varied as desired. For example, the plug 17v may be secured in the face 11 prior to nosing in the other end of the blank. It will be obvious that such changes may be made in the described method Without departing from the spirit of this invention or the scope of the appended claims.

What I claim as new and desire to secure lby Letters Patent is: v 4

1. The method of making a shell forging which consists in providing a tubular blank, machining the interior of said blank, forging one end thereof so as to provide a closed, substantially flat end shell base, drilling the center of said closed end to remove oxides and porosity, shaping the other end of said blank to form a tapered nose, shaping the interior of saidnose and closing the drilled opening in said base from the' outside thereof.

2. The method of making shells which consists in machining the interior of a tubular. blank to provide a predetermined interior diameter thereof, shaping one end thereof to form a fiat closed shell base,'drilling'a tapered opening through the center of said base from the outside to the inside thereof to remove impurities, forming a tapered nose on the other end of said blank and plugging the drilled opening in said base from the ontside thereof.

3. The method of making a shell vforging which consists in providing a tubular blank,

machining the interior of said blank, shaping oneend thereof so as to provide a closed substantially fiat end, drilling the center of said closed end to remove impurities therefrom and to provide a conical inwardly converging hole, tapering the other end of said blank to form a nose, enlarging the interior of said nose, inserting a plug in said hole from the outside of said fiat end and pressing said lug so as to eifectively close the base of the org- 4. The method of making shells which consists in hot rolling a steel blankto form a solid rod, simultaneously rolling and piercing saidrod to form a tube, and size rollingl the tube so produced, cutting the tube to length, shaping one end thereof to form a cylindrical blank closed at one end, boring out the center of the closed end of said blank, securing a steel plug in the opening so formed and nosing in the opposite end of the blank.

5. The method of making shells which consists in hot rolling a steel blank to form a solid rod, piercing and rolling said rod to form a tube, shaping one end of said tube to provide a cylindrical blank closed at one end, boring out the center of the closed end of said blank, closing the opening so formed and nosing in the opposite end of the blank.

6. The method of making shells which consists in hot rolling a steel blank to form a solid bar simultaneously rolling and piercing said bar to form a tubular blank, sizing said tube, shaping one end thereof to form a closed flat end, nosing in the opposite end of said blank and shaping the interior diameter of said nose to receive a fuse.

7 .I The method of making a shell forging which consists in providing a hot rolled seamless tube, machining the'interior of saidtube, upsetting one end thereof to provide a closed end, redrilling and plugging said closed end from the outside thereof and forging the other end of said tube to form an open nose.

8. The method of making a shell forging which consists in providing a hot rolled seamless tube, upsetting one end thereof to provide a closed end, drilling the center of said closed end to form a tapered opening having inwardly converging walls, closing said opening by a tapered plug, compressing said plug within said opening and shaping the other end of said tube to form a tapered nose.

In testimony whereof, 1 have hereunto subscribed my name this 4th day of December,

y GILBERT P. MCNIFF.

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