US2325079A - Heat treatment of projectiles - Google Patents

Description

July 27, 1943 w. H. soDERHoLM HEAT TREATMENT 0F PROJECTILES 3 sheets-sheet 1 Filed June ll, 1941 JUNCT/UN BOX JUNC770N BOX July 27, 1943- w. H. soDl-:RHoLM HEAT TREATMENT OF PROJECTILES 3 Sheets-Sheet 2 Filed June 11, 1941 July 27,l 1943. w. H. soDERHoLM HEAT TREATMENT OF PROJECTILES Filed June l1, 1941 pense and time;

Patented July 279 i943 l andere naar raisers/mur or rnornernns Walter iii. Soderholm, lllnited States Army, Syracuse, il.

Application .lune llllllilllll, Serial No. 397,651.

is claims. (ci. ire-ic) (Granted under the act of March 3, m83, as amended thrill 30, llf; 37@ (il. G. T57) The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

My invention relates to the heat treatment of ordnance projectiles whereby the fragmentation of the projectile is controlled.

Previously, in the manufacture of high explosive fragmentation shells it was necessary to produce sections of relative weakness in the shell body by grooving the outside or inside surfaces of the shell or by adding strengthening rings so as to obtain a controlled fragmentation of the shell. In many cases this required additional machining operations on the blank shell or required an elaborate casting or forging. In any event additional metal was required over and above that necessary to provide a shell strong enough to withstand normal handling. Due to the irregular portions ron the outside surface, the shell would be needlessly impeded by air resistance, or due to the presence of the irregular portions on the inside of the shell, the amount of bursting charge which could otherwise be conned would bev diminished. in order to provide a fragmentation shell from a blank shell it was necessary to addadditional material, weight, ex-

there is a marked reduction in the amount of material, weight, expense and time necessary to produce a fragmentation shell in accordance with my invention as will clearly appear from the description of my invention.

The fragmentation shell produced by the apparatus and method described herein is described and claimed in my divisional application, Serial No. 413,306 nled October 2, 194i.

An object of my invention is to provide apparatus for furnishing a high explosive projectile which has strengthened portions or zones incorporated within the body of the projectile material.

Another object of my invention is to provide apparatus for heat treating zones or portions of the projectile material whereby subsequent fragmentation of the projectile is controlled.

Another object of my invention is to perform a. heat treatment on a high explosive projectile so that portions on the inside surface or outside surface of the projectile may be strengthened.

Another object of my invention is to provide an arrangement of induction heating coils and quenching ducts for heat treating a high explosive projectile whereby its fragmentation may be controlled.

Another object of my invention is to provide an -and inside of the shell arrangement whereby relative portions of the body of a high explosive projectile are strengthened without resorting to machining or elaborate forging operations.

Another object of my invention is to provide apparatus for furnishing a fragmentation controlled projectile body at a smaller manufacturing cost and with less time consumption than .those heretofore existing.

Another object of my invention is to provide apparatus for furnishing a fragmentation controlled projectile shell which has a smooth outside surface and also a smooth inside surface so that the minimum air resistance is oered to the projectile in flight and a maximum amount of bursting charge may be incorporated within the shell.

Another object of my invention is to provide apparatus for furnishing a fragmentation controlled shell which requires no additional rings or grooves to be formed on the cylindrical surfaces of the projectile shell to produce a controlled fragmentation.

Another object of my invention is to provide apparatus for furnishing a fragmentation controlled shell of relatively light weight.

The nature and objects of my invention will be clearly revealed in the following description and accompanying drawings wherein:

Fig. l represents the heating coil and quenching duct arrangements disposed on the outside and means for selectively controlling the energization of `the heating coils.

Fig. 2 discloses the arrangement of strengthened portions when the o tside heating coils only were energized.

Fig. 3 discloses the arrangement of strengthened portions when the inside heating coils only were energized.

Fig. i discloses the arrangement of strengthened portions when both the inside and outside heating coils were energized.

Fig. 5 discloses a view taken on line t-ii of Fig. l.

Fig. 6 discloses a modification in which noz- Zles are mounted on the spool-shaped centrally disposed spacer members.

Fig. 'l discloses a gas flame arrangement for heat treating the shell.

In this particular instance my invention is shown in relation to' an antiaircraft shell and might be applied before or after the nosing in operation has been performed on the shell; it is understood however that my invention is not limited exclusively to the particular type of shell `numerals indicate like parts.

projectiles so as to control their fragmentation.

Reference ismade to the drawings wherein like The shell III is held in the heat treatment apparatus on the base plate I1 by gravity and in centered relationship to the heat treatment Aapparatus by the circular projection II. Magnetic induction coils I2 are equally spaced within the shell and magnetic induction coils I3 are equally spaced'surrounding the shell and on the same horizontal planes with the inner coils I 2.' The inner coils are spaced by spool-shaped members I4. The entire inner column of coils I2 and spacers I4 is supported on the washer I5 which is heid against downward movement by the iixed flange I5'. The coils I2 may be `.adjusted for height by making usel of the threaded connection I8 between the tube I6 and base plate I1. 'Ihe centrally disposed tube I6 has an indentation I9 on its outer surface which serves to prevent rotation of the spacers I4 with respect to the tube and also to serve as a conduit for the individual coil leads 2U which might be threaded through a cable Each spacer I4 has a. transverse hole 2| through which the leads from one coil pass and also lugs 22, Fig. 5, which are adapted to cooperate with the inside corners 23 of the centrally disposed member I6 so as to prevent relative rotation.

A hole 24 in the base plate I1 provides an exit for the coil leads.

The upper end of tube I6 is provided with a small opening 21 so as to allow passage of the quenching iiuid which might be water or oil. Holes 25 in the centrally disposed conduit I6 are arranged so that they are aligned with the holes 26 in spacers I4 thus allowing most of the` quenching iiuid to be squirted through those holes in the most effective regions. The holes 25, 26, 21 are graduated in size so that practically a uniform spray is produced in the interior of the shell; the holes are enlarged more and more 'as the distance from the source of supply is increased so as to compensate for the pressure drop of the quenching uid If desired, nozzles 28 may be mounted overeach quenching fluid opening in thespacers as shown in the modification in Fig. 6 in order to more positively direct the quenching liquid to the heated shell surface although the addition of such nozzles is not deemed vitally necessary to carry out my invention.

The coils I3 are spaced by the circular channel shaped members 29 which have circumferentially disposed'holes 40 alignedwith holes 30l in the jacket 3l. The row of coils I3 is supported on the washer-shaped member 32 which is held against downward movement by a fixed bracket 33. The jacket 3I has a recess 34 which serves as a conduit for the leads of coil I3; the inner edges 35 and 36 cooperate with lugs 31 and 33 on the circular channel-shaped members 29 so as to prevent relative rotation between members 29 and jacket 3.

'Ihe coil mounting structures for coils I2 and I3 are preferably of non-metallic material and it is desirable that the shell metal itself is the only metallic material through which the ux from coils I2 and I3 is caused to pass.

The jacket 3| is supplied with quenching uid which passes through the tubular opening 4I.

Gate valves 42 and 43 serve to limit the now disclosed and might be applied to other ordnance eter but some of them may be enlarged so that Y to the ones shown in Fig. 6 may be mounted in relationv to each opening 40 so as to serve as more positive directing means for the quenching uid.

All ofthe quenching uid must pass through a magnetically operated valve 44. Magnetically operated valves per se are well known in the fluid distribution art and for that reason the particular structure of this valve is not disclosed. The valve is of the type in which movement of the magnetic member 45 upon energizaton of solenoid winding 46 opens the valve 44 to allow a flow of iluid; upon deenergization of winding 46 the valve 44 is biased by means not shown so as to close the valve. The coil 46 is energized from a battery 41 through a single pole, double throw switch 46 which has one set of terminals to which no wires are connected.

The leads 2U from the inner coils pass through the opening 24 to a junction box 49 and the leads 5I) from the outer coils which are threaded through a cable 50 pass through the opening 5I to the junction box 52.

The inner or outer coils I2 or I3 may be connected in series or in parallel at the corresponding junction box or in any other manner dei sired.`v When the coils I2 or I3 are connected in series with one another-then the net effect of the component coils I2 or I3 is to form a coil proper with each coil I2 or I3 a component of the coil proper. The coils might be connected with respect to one another so that the same amount of current does not pass through each one of the coils if it is desired to produce compensating eifects. Variable resistors 53 and 54 serve to control the amount of current'fiowing to the coils I2 and I3 respectively.

The double pole, double throw switch 55 serves to energize the leads 50 from an alternating current source 56 through transformer T1 and leads 53. Two terminals of the switch 55 are left uny 58. Two terminals of the switch 55 are left unconnected as indicated in Fig. 1.

As a precautionary measure the double throw switches 48, 55, and' 51 may be interlocked (not shown) so that switch 48 is prevented from being closed when either switch 55 or switch 51 is closed; this would prevent the shell being needlessly cooled andA heated at the same time.

It is obvious that the inner and outer coils may be individually or simultaneously energized so that at the election of the operator inner rings of the shell material may be heated or the outer rings of the shell material may be heated or else the inner and buter rings of the shell material may be heated simultaneously. A subsequent rapid cooling of the heated parts will produce a hardening of the material winch was heated so that the shell has hardened portions as indicated in the drawings.. Fig. 2 discloses the result obtained when the outside heating coils were energized; the dotted portions signify the hardened portions. Fig. 3 discloses the result obtained when the inside heating coils were energized and the dotted portions signify the hardened portions.

Fig. 4 discloses the result obtained when both the inside and outside coils were energized and producing ll. (a) Closes switch 55 or (b) switch 5l or (c) switch 55 and switch 5l, depending upon the desired location of the hardened zones,

" 2. Opens all the switches which were closed in step l, and then 3. Closes switch it to cool the material.

lihc shell material is heated due to eddy currents and/or hysteresis losses in the shell material itself. is necessarily generated in that region through which the flux passes in accordance with wellrecognized principles.

High frequency currents may be used to great advantage in producing a heated Zone near the surface of the shell material. The alternating fluir. through the coils l2 and iii causes an alternating flux to pass through the shell material;

The heating is local in edect and 'd the magnitude of the eddy currents produced in the shell material is in proportion to the freb quency of the alternating current and these eddy currents set up magnetic fields of their own which tend to decrease the distance which 'the coil nur. penetrates the shell material. The above phenomenon is commonly referred to'as eddy current shielding and is made of advantage in a heated zone near the surface of the material. It is highly desirable that those portions which are to be hardened be heated above the hardening temperature very quickly and also quenched very quickly; otherwise the heat generated would have time in which to diiuse into the body of the material due to the good heat conduction of the body and instead of having sharply defined hardened bands in the shell there would be a hardening of that-material which is not desired to be hardened. The electrical control arrangement described allows rapid operatien. The power supply and connected circuits should be of sufficient size and have sufcient regulation to cause the shell material to be heated to the quenchingl temperature in the shortest possible time thus assuring a minimum, amount of heat diusion to the surrounding material.

The electrical and magnetic apparatus disclosed serves as one of the means by which a heat treated fragmentation shell of the type described may be produced. IThe embodiment of my invention thus far described is my preferred embodiment and it is understood that other means may readily be suggested; for instance, the portions of the shell to behardened may be supplied by heat from a sharply dened gas flame which is movable with respect to the shell as in Fig. 7. In Figure '7, the shell l@ is held and rotated by a lathe chuck 9U. Gas burners llt and liti supply heat to shell respectively. of the shell material will be heated above the temperature of its surrounding material. The ow of gas to the burners is controlled by the valves M2, it and duid is controlled by valve |145. The valves l `and M5 may be interlocked by means well known the inside and outsideof the As the shell is rotated rings Ulli. The flow of quenching in the art. The auxiliary valve it@ serves as an exit for any quenching fluid remaining in the gas pipes after the quenching operation.

It is to be understood that my invention is not limited to the production of a fragmentation shell of the type disclosed but my invention in its broader aspects may be applied in the production of ordnance matriel wherein it is desired to produce different degrees of strength or hardness in portions of the ordnance matriel.

In general my invention may be applied in the production of hand grenades, time delay bombs, projectiles or other fragmentation body so as to control the'uniformity of the particles which are fragmented by the bursting charge contained therein. f

I claim:

l. In the art of producing a fragmentation controlled shell, the apparatus comprising more than two spaced coaxial coils adapted to partially encase the shell, orifices disposed between adjacent coils, means to project a stream of liquid through said orifices, means for maintaining the shell stationary with respect to the coils, and means for spacing said coils whereby rings of the shell material are heated when high frequency current is passed through the coils.

2. In the art of producing a fragmentation controlled hollow shell, the apparatus comprising more than two spaced coaxial coils adapted to be disposed within the interior portion of the shell and in close proximity thereto, orifices disposed between adjacent coils, means for projecting a stream of liquid through said orifices, means for maintaining the shell stationary with respect to the coils, and means for spacing said coils whereby rings of the shell material are selectively vheated when high frequency current is passed through the coils.

3. in the artof producing a fragmentation controlled shell, the apparatus comprising more than two spaced coaxial coils adapted to partially encase the shell, means foi` producing a spray of liquid within the cylindrical space defined by the coils, means for maintaining the shell stationary with respect to the coils, and means for spacing said coils whereby rings of the shell material are selectively heated when high frequency current is passed through the coils.

ll. In the art of producing a fragmentation controlled hollow shell, .the apparatus comprising more than two spaced coaxial coils adapted to be disposed within the interior portion of the shell and in close proximity thereto, means for producing a spray of liquid within the space surrounding the coils, means for maintaining the shell stationary with respect to the coils, and means for spacing said coils whereby rings of the shell material are selectively heated when high frequency current is passed through the coils.

5. In the art of producing a fragmentation controlled than two spaced coaxial coils adapted to partially encase the shell, means for maintaining the shell stationary with respect to the coils, and means for spacing said coils whereby rings of the shell material areselectively heated when high frequency current is passed through the coils.

6. In the art of producing a fragmentation controlled hollow shell, the apparatus comprising more than two spaced coaxial coils adapted to be disposed within the interior portion of the shell, means for maintaining the shell stationary with respect to the coils, and means for spacing said coils whereby rings of the shell material are selecshell, the apparatus comprising moretively heated when high frequency current passed through the coils.

7. In the art of producing a fragmentation controlled hollow shell, the apparatus comprising a set of more than two spaced coaxial coils adapted to partially'encase the shell, a set of more than two spaced coaxial coils adapted to be disposed within the interior portion of the shell and disposed coaxially with said first mentioned set, means for maintaining the first mentioned set stationary with respect to the shell, means for maintaining the second mentioned set stationary with respect to the shell and coaxial with the first mentioned set, means for `spacing the coils of the first mentioned set whereby rings of the outer shell material are selectively heated when high frequency current is passed through the coils yo1' the first mentioned set, and meansfor spacing ,fthe coils of the second mentioned set whereby ,f rings of the innershell material are selectively heated when high frequency current is passed through the c oils ofthe second mentioned set.

8. In the process of yproducing a fragmentation body from a smooth surfacedubody the steps l which comprise, heating selected portions of the smooth surfaced body and then quickly quenching the selected is controlled.

9. In the process of producing a fragmentation lbody from a hollow body having an outer smooth surface and an inner'smooth surface, the steps which comprise heating selected portions of both smooth surfaces, and then quickly quenching the portions, whereby fragmentation selected portions so as to control the fragmenta- `Ition of the body. l

10. In the process of producinga fragmenta-l` compriseheating selected portions of the inner and outer smooth cylindrical walls, and then quickly quenching .the selected portions, whereby fragmentation is controlled.

l0 11. In the process of producing a. fragmentation shell from a hollow shell having smooth cylindricalinner and outer walls, the steps which comprise selectively heating ring-like portions of the inner and outer walls and then quickly l.; quenchingv the heated portions.

12. 'I'he same as claim 7 and the plane of each coil of each set is coplanar with a corresponding coil of the other set.

13. The process of augmenting the fragmentation characteristics of a high explosive container formed of a ferrous metal of substantially the same composition throughout the surface area, which comprises, heating predetermined areas of the container at such a rate and to such a temperature as to permit hardening of areas of controlled depth of the container wall, terminating the heating when said areas attain the hardening temperature and chilling the areas so heated at such arate as to increase the hardness of the same whereby the container walls are formed of areas of relatively high and low tensile strength.

WAL'I'ER H. sODERHoLM.

Gru.

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