US2047296A - Apparatus for forming propeller blades - Google Patents

Description

July 14, 1936. J. SQUIRES APPARATUS FOR FORMING PROPELLER BLADES Filed July 5, 1-933 4 Sheets-Sheet 1 ATTORNEYS.

m T N E V m July 14, 1936. J, E 2,047,296

APPARATUS FOR FORMING PROPELLER BLADES Filed July 5,, 1955 4 Sheets-$heet 3 I E z 4 1 m a 6 a .z o a z w .ZE z 9 4 i 6 y Jl k \\\k l w m w a 7 5 3 6 4 4 2 7 2 5. a w w, 33 3 5.0:? 4 him. f 4 I I M a w a M J W J a .z ,r a. a L a .h 5 w W 4 23. 0 .Z M l m w f \lk W m f m 5 A 1 w 5 July 14, 1936. J. SQUIRES 2,047,296

APPARATUS\FO R FORMING PROPELLER BLADES Filed July 5, 1933 4 Sheets-Sheet 4 mo W W Pier-55 INVENTOR 6Q a; re s.

- I BY Y :I'ORNEYS. I

1931, Serial No. 530,541..

, Patented Jul 14, 1936 umrsli STATES PATENT OFFICE.

2,041,296 arrannrusron roams rnornnrna BLADE k .lohn Squires, Hagerstown, Md. Application July 5, 1933, Serial No. 679,134

42 Claims.

' Objects of the invention relate to an improved apparatus for proved apparatus in. which a heated blade blank may be quickly positioned for receiving a pressin; operation, immediately upon removal from aiurnace, and before the temperature of the blade decreases materially; to provide means in apparatus of this kind for supporting a propeller blade blank by engagement only with its rootend-portion which is not deformed in the press ing operation was to obviatethe cooling efiect which would otherwise be caused by contacting of the remalningparts of the blank'which are .to be deformed, with the dies and their support-' ing structures; to prevent unintended deformation in restricted .areas of the shed product by a precooling of limited areas of the blank; to

provide a'yieldably mounted supporting structure for holding a heated propeller blade blank between, and in spaced relation'to a pair of forming dies which is adapted'to guide the movement or the blade, as the dies are brought to- .gether, so as to properly place the blade in the .die depression; to provide a yieldably mounted support of this kind which is movable axially oi the die depression for permitting inwardmovement of the root end of the blade during shrinking thereof upon cooling after it is pressed 1 to the desired blade shape; and to provide a. detiachable holding member in a supporting strum ture of this characterior receiving the flanged root end portion of the blank; which is adapted to be removed and replaced so as to condition the supporting structure for receiving blanks oi difierent sizes and shapes.

Other objects include the provision or a die structure of novel conformation for pressing a propeller blade blank to blade shape; to provide such a die structure a portion of which may be employed in pressing bla to blade shape regardless of the, length 01 the blade; to provide such die structure in which the end portion thereof employed for pressing portions of the blade are readily removable and replaceable by corresponding portions adapted for use in formlng blades of different characteristics; and to provide dies and apparatus for forming propeller blades which are fabricated from two or more forming propeller blades; to imchange between a heated blade tinuously controlled during production of such structures during the repetitions of the compressing operations. which occur within short time intervals in manufacturing propeller blades on a production basis; to provide improved means for mounting the dies in the die holders y means of, which dies of various dimensions may be secured in place; and to provide means and apparatus whereby the rate of heat interblank and the forming dies therefor may be accurately and conblades so as to effect the desired physical structure in the finished blade. Other objects are to provide improved mechanism in propeller blade forming apparatus for forming a communicative connection between the interior of a tubular propeller blade blank and a source of pneumatic pressure so as to internally support the blank against collapsing during the compressing \operation; to provide mechanism of this character which is adapted to quickly form a hermetically sealed connection to the open end of a heated propeller blade blank before a substantial reduction in the temperature of the -blade occurs; to provide a sealing member for the open end of the tubular blank which has a greater area exposed to the source of pressure than that which is exposed to the internal pressure of the blank so as to create a, substantial pressure diderential on the outside of the sealing member so as to tend to firmly hold the latter in a hermetically sealed condition against the open end of the blank by pneumatic pressure; to provide sealing means of this kind in which the pressure diderential is augmented by reductions in pressure in the interior of the blank such as are caused by leakage or air from the open end thereof. 0 A Other objects of the invention are to provide a yieldablymounted supporting structure for receiving the flanged end of a propeller blade blank in which a passage is formed for' conducting a cooling medium around the flanged end portion of the blade; and to provide asupporting structure of this kind which may. be 'used in conjunction with die holding members having cooling medium passages so as to cool the entire converted by the addition blade uniformly and with pneumatic pressure applying apparatus during a quenching operation in which the outer faces of the blade are pneumatically urged against corresponding surfaces of the die.

Other objects include the provision .of dies for pressing a propeller blade blank to blade formation in which certain portions of the die de-- pressions are of greater dimensions than the corresponding portions of the blades to be formed thereby; and to provide such dies in which that portion of the die depressions adapted to form the tip end of the blade are of greater lateral and longitudinal dimensions than the corresponding portions of the blade to be formed thereby.

The above being among the objects of the present invention, the same consists of certain novel features of construction and combinations of parts to be hereinafter described with reference to the accompanying drawings, and then claimed, having the above and other objects in view.

In the accompanying drawings which illustrate a suitable embodiment. of the present invention and in .which like numerals refer to like parts throughout the several different views,

Figure 1 is a side elevationalview of a hollow metallic blank adapted to form a. propeller blade when properly acted upon by suitable apparatus.

Fig. 2 is a transverse secti nal view taken on the line 2 2 of Fig. 1.

Fig. 3 is a side elevational view of a pro eller blade which has been formed from a bla of the character disclosed in Figs. 1 and 2.

Fig. 4 is a transverse sectional view taken on the line 4-4 of Fig? 3.

Fig. 5 is a fragmentary perspective view of an improved forming apparatus preferably employed for pressing the blank indicated in Fig. 1 to blade shape, showing parts thereof removed to disclose. the underlying structure. i I

Fig. 6 is a horizontal sectional view taken centrally through the forming apparatus as on the line 6 6'of Fig. 7, showing the dies thereof in closed position and illustrating the mannerin which'the blank is mounted and internally supported.

Fig. '7 is a vertical sectional view taken on the line 1-1 of Fig. 6.

Fig. 8 is a fragmentary partially broken top plan view of the apparatus illustrated in Fig. 6,

a portion of the upper wall having been removed to disclose the cooling medium passages therein. Fig. 9 is a'front end view of the forming apparatus showing the die holders and, diesein their adjacent closed position.

Fig. 10 is a transverse vertical sectional view taken on the line l0- -ifl of Fig. 6.

' Fig. 11 is a. front end view, similar to Fig. 9, but showing the die holders and dies spread apart and the blank supported between the dies in spaced relation to both thereof. I

Fig. 12 is a fragmentary vertical sectional view taken on the'line l2'l2 of Fig. 8. t

Fig. 13 is a fragmentary perspective view of a quenching apparatus into which the forming,

apparatus above disclosed may be conveniently of. accessory equipment and showing a further development of this phase of my invention.-

Fig. 14 i's"a ,front end elevation of the structure in Fig. 13

Fig. 15 is a fragmentary longitudinal sectional view taken vertically through the center of the,

. ticularly in the larger structureshowii in Figs.'13 and 14, as on the line lS-IS of Fig. 14.

Figs. 16, 17, and 18 are views corresponding to a fragment of the views shown in Figs. 6, 7, and 10 respectively, showing a variation in the formation of the die depressions from that shown in the previous figures.

Referring to the drawings, in Fig. 3 is shown a propeller blade of the hollow metallic type including a main body I00 having a t p I02 on one end thereof and a radial flange I 0 at the other end thereof, the flange 16 serving as a means for securing the blade in a hub (not shown). The body l00.of the blade for the greater part of its length is of course formed to an airfoil section such as indicated in Fig.i4 to provide a leading edge I08, a trailing edge H0, a front or camber face. 0a and rear or flat face Ilflb. It is of course also understood that the body I 00 of the blade is twisted or warped over its length so that each increment of length has substantially the same pitch with respect to the axis of rotation of the propeller of which it is to form a part. In accordance with the present invention, the blade shown in Fig. '3 is formed from a blank of ethe general type indicated in Fig. 1, namely, a hollow metallic blank 2, which may be formed from any suitable metal but which, for the purpose of illustration only, may be considered as formed from a suitable low carbon steel and preferably of a type similar to the types known as S. A. E. 4130,X and S. A. Ee6135. As indicated in Fig. 2, the blank H2 is preferably of circular section and one end thereof is tapered down or reduced in diameter to form a small closed end or nose section I34 and the flange [08 is preferably formed at the opposite end prior to its being pressed to the blade formation indicated in Fig.3. The wall thickness of the blank preferably decreases. from the flange I06 toward the small closed end or tip but as pointed out in the application of which the present application is a continuation in part, the extreme tip end of the blank 2- -is preferably, particularly in the larger sizeseprovided with a tip end wall of increased thickness as coinpared to the adjacent portions of the blank. Also it is preferable, parsizes of blades, to provide a small nipple I H on the extreme point of the closed end of the blank to prevent splitting of of this method is given at'this point. It will be understood that the die structure includes two main parts relatively movable toward and away from each other, the adjacent faces of theparts having opposed depressions therein which coopera'te, when the dies are in closed position, to form a recess of the exact shape and contour and, preferably, except, for the "outer stages of .the blade, as will be explained in greater detail, the exact size or the desired finished blade. In this connection it may be noted that in the broader aspects of the present invention the die depressions may cooperate to form a depression conforming exactly throughout to the exact size, shape and contour of the desired finished blade as hereinafter shown and described, but a more limited phase of my 'invention deals with making the outer or tip stages of the depressions widerand.

longer than the corresponding portions of the between the die pits and its interior is placed under a suitable air pressure, and the dies are then brought together, causing the exterior of the blank to assume the shape of the walls of the die depressions. The purpose of placing the interior of the blank under air pressure is to cause it to be expansively pressed outwardly into contact with the walls of the die depressions during the pressing operation, thereby insuring substantially complete contact between the blank and the walls of the depressions over the entire outer surface of the blank. The air pressure employed for this 7 purpose, while high enough to insure the eflectiveness of its purpose is, of course, not sufll'ciently high to endanger bursting of the walls 01' the [;blank. 'It has been found that an air pressure of three hundred pounds per squareinch is usually ample for the purpose described, but this pressure may vary in accordance'with the size and wall thickness of the particular blank being worked upon. In applying such air pressure to the interior of the blank it is, of course, necessary for optimum results that such pressure be exerted at the desired mardmum value substantially immediately upon admitting the air to the blank and be maintained at such value during theoperation. For this reason it is preferableto employ an air reservoir tank (not shown) in connection with the air supply and maintain the pressure in it at a suijficiently high figure to insure an ample sup- "ply of air for the operation at the desired value.

In any caseit will be apparent in connection with this phaseof operation that the temperature of the blank and the pressure of the air to which the interior of the blank is subjected have, of

course, a certain relation between them, the temperature necessarily being such as to permit the necessary bending of the walls of the blank into blade formation without causing any undesirable stress or fracture of the metal of the walls and, of course, sumciently high to insure the internal "pressur of the air forping the blank into 'substantial contact with all surfaces of the die depressions when the dies are brought together, but preterably a temperature not so high as to pert the expansive force of the air to stretch the metal or the blank. [a

In placing the heated blank between the dies, it is further desirable to maintain the main body portion of the blank out of contact with the dies until the dies are actually brought together, for otherwise any area of the blank which contacted with the dies might be cooled to such an extent that whe the dies were brought together that area woul ave become so rigid as not to properly conform to the shape of the corresponding depression wall area of the dies. Unequal cooling might also set up undesirable unequal stresses in the metal at various points in the blank. In view of the fact that the shank or root end portion of .the blank is not deformed during the pressing operation, this portion of the blank is preferably employed for supporting the blank in thedies before the dies are brought together as it thus makes little difference whether it is pro-cooled or not.

Where the dies are employed for successively forming a large number of highly heated blanks to ,bladeshape, by repeated contact with successive hcatedblanks the die parts in some cases are liable to be heated to such a degree as to become detrimental, and for this reason it may be preferable to-provide suitable means for regulating the temperature of the die parts. This may conveniently be accomplished by circulating a con trolled supply of water through the die parts.

v Furthermore, in view of the fact that a preferred later step in the manufacture of the blades is a quenching operation to harden the blade mate- 10 rial, and a preferred method of quenching the blades is to place them between relatively cold die parts contacting substantially the entire outer surface of the blades, the same die parts as are employed for forming the blanks to blade shape 15 may be employed in quantity production for the quenching operation if suitable means are pro-. vided for cooling the die parts. The water passages reierred to above offer a suitable means for 1 accomplishing the desired cooling of the die parts. 2.0v

In the form shown-in Figs. 5 to 12, inclusive, my 1 improved propeller blade forming apparatus includes a. lower block or die holder 250 which nor- ,mally rests upon the lower platen of a press, and

is provided with a longitudinal recess 252 which 25 is bounded by a vertical side wall 256 and an inclined side wall 256. As indicated in Fig. 7, the die holder 250, is cored internally or otherwise vsuitably provided with passages 258 for circulating a cooling medium substantially throughout 30.

' its entire length andbreadth. As best indicated in Fig, 10, the passages 25B are provided with a communicating inlet 26d, and a communicating outlet 262 which, in practice, are connected to a convenient source of water supply and drain pipe 35.

respectively. g

Formed on the frontpcorner portions of the lower die holder 250 are upright posts 26d of substantially rectangular, cross-section. An upper die holder 2% having a recess 2th which is com- 549 plementary to the recess tfiliof the lower die holder 25B is mounted in superimposed relation thereon. The opposite front corner portions of the/upper die holder 2% are provided with recesses till for slidably receiving the posts tilt of v the lower die holder tilt. The side walll'll of the recess 2th is vertical and is located substantially in alignment with the side wall rat of the lower recess 2%, and'the other side wall tilt of the recess 268 is inclined oppositely with respect 50 to the side wall 2% of the other recess.

Seated in the recesses 252 and 26d of the die holders 2% and 2% are dies tilt and till respectively having longitudinally extending blade forming recesses M8 and M9 respectively formed .55 intheir'opposed faces which recesses cooperate to form a single recess which conforms in size, shape, contour and pitch truth the size,shape and contour, except for the nose end as will hereinafter be more fully explained, and pitch of the so finished blade shown in Fig. 3 which it is desired to form. The die parts lit and till are preferably split transversely of their length and intermediate their ends as at 281i and are detachably v secured to their respective die holders by longi- 5 tudinally extending gibs or wedge members 28d and 285 (see Fig. 10) which are held in place by bolts 288 and 290 respectively screwed into the die holders 250 and 266 respectively. The dies are held against outward or lateral displacement 7 from the recesses by the inclined walls thereof and by the inclined sides of the gibs 284 and 286.

By replacing those portions of the dies 216 and 211 inwardly of the line of split by portions of either greater or lesser length than those shown,

the same outer die portions may be employed to produce blades of different lengths. By this means a considerable saving in die costs may be realized in the production of bladesof different lengths. It may be desired to employ various butt end die sections withvarying tip end die sections and the construction described makes them easily interchangeable to produce any desired combination, without the necessity of making complete dies of all the various types needed.

It will also be noted from an inspection of Figs. 6, Land 10 that the depressions 218 and 218 in the dies 216 and 211 are wider and longer than the corresponding portion or the blade in the outer stages thereof. This may exist for as much as sixty percent of the length of the blade toward the tip end. This is arranged by extending those surfaces of the die depressions 218 and 219 which give such portion of the blade its desired surface conformation in length, out to near the parting line of the dies, and extending the corresponding surfaces of the dies laterally to near the parting line in a tangential direction with respect to the natural radius of the respective edge portions of the blades formed therein. This permits the making ofblades of various lengths with the pitch twist continuing uniformly together with the proper longitudinal and lateral conformation.

It is to be understood that except for'the outer portions of the depressions 218 and 218 which may be made wider and longer than the corresponding portions of the blades to be produced thereby, as above pointed out, the perimetrical dimensions of the die depressions at any given transverse cross section through them is substantially equal to the peri'inetrical dimensions of the corresponding section of the blank 2 to be shaped between them, so that when the blank is pressed to blade shape, no outward stretching or inward crowding of the metal of the blank occurs, such metal being merely bent to shape.

The upper die holder 266 is internally cored or otherwise suitably provided with cooling medium passages 292 which communicate with a supply pipe 284 and a drain pipe 296 at the opposite sides of the holder.

A pair of parallel plates 298 are located adjacent the outer sides of the upright posts 2640f the lower die holder and are rigidly secured thereto by bolts 388. The plates 288 protrude beyond the forward ends of the die holders and they are provided at their outer extremities with wardly extending cleats 382 which are secured in place by bolts 384. The cleats 382 formchannel ways 386 between their inner sides and the front edges of the posts 264 in which side flanges 388 and EH8 of a channel shaped support or cross head 3E2 having a weby3l4, are slidably received. As best shown in Figs. 6 and 12, the inner edge portions of the flanges 388 and 3l8 are provided with recesses 316 in which shoes 3l8 preferably comprising rectangular metal bars, are seated. The shoes 3l8 carry pins 328 which are received in apertures 322 formed in the posts 264 of the lower die holder 258 and the shoes are yieldably held in spaced relation to the posts 264 by springs 324 which surround the pins 328 and are seated in recesses 326 in the forward edges of the posts and surrounding the apertures 322. These shoes 3l8 normally bear upon the cross head 3l2 urging the same outwardly against the inner sides of the cleats 382.

As best shown in Fig. 11, the entire cross head 3i2 is yieldably supported on coil springs 328 'lows 346, but this may not be essential. The

which are seated upon the lower press platen 338. The springs 328 normally hold the cross head M2, and the blank 2 when supported thereby, more or less centered between the dies and out of contact with both dies, as indicated in Fig. 11.

The web 3 of the cross head 2 is provided with an enlarged central opening 338 of circular contour in which a collar- 332, for receiving the shank portion of the tubular blank 2 adjacent 10 the flange I86 thereof, is detachably mounted by screws 334. The collar 332 is provided with preferably horizontally andlaterally extending slots 336 which may register with the flattened portions toward the leading and trailing edges which are formed on the resulting blade and permit the blade to be withdrawn from and through the collar during removal of the blade from the forging apparatus, The forming apparatus may be readily conditioned for manufacturing blades of various dimensions by removing the collar 332 and replacing it with a collar of suitable inner diameter and "by substituting proper dies or die sections for the dies 216 and 211 shown. The cross head 3l2 serves as the sole support for the propeller blade blank 2 before the dies are brought together and by reason of the elevated position in which it is held by the springs 328, it locates the tubular blank 2 in spaced relation between the dies 216 and 211 when they are spread apart and in registration with their recesses 218 and 218 and holds the blank out of contact with the dies and their supporting structures so as to prevent cooling of localized areas of the blank before compression thereof to blade shape.

In supporting the blank internally by pneumatic or other fluid pressure after it is positioned in the collar 332, it is necessary to form a communicative connection between the open end of the blank and a source of pressure in a brief time interval in order to prevent excessive cooling of .the blank before the forming operation. This is successfully accomplished by providing the connecting means on a. breach block 338 which is swingably mounted on a vertical breach block pin 348 that is mounted in brackets 342 on the flange 3| 8 of the cross head 3 l 2. A relatively positive seating of thegair inlet 356 on the flange I86 should be provided:\= '1'his may be accomplished by a suitable washer or other contacting member, or the contacting member maybe somewhat resilient. Such a resilient seating device is illustrated as provided by the sylphon or belinner side of the breach block 338 has a recess 344 in which'the outer end of a metallic bellows or sylphon 346 is suitably secured in sealed relation therewith. Mounted on the inner end of the bellows or Sylphon 348 is a head 348 haying a central protruding boss which is received in the open end of the tubularvblank H2. A washer or gasket 358, preferably comprising copper or other suitable material, is provided between the flange I86 of the root end of the tubular blank 5 and the face of the head 348 for forming an air tight seal between the head of the bellows and the flange of the blank.

Leading to the interior of the bellows 346 and formed in the breach block 338 is an aperture 352 in which a nipple of an outwardly extending vvalve 354 is mounted. The valve 354 communicates through a flexible connection with a source of pressure (not shown) and when open supplies air or other gas under pressure to the interior 76 is releasably held in a of the bellows 346 and from the latter to the interior of the tubular blank through an orifice 356 in the head 3480f the bellows. The side of the head 348within the bellows 346 is larger in area than the end of the base which extends into the open extremity of the blank and therefore a force differential is created by the pressure on the opposite sides of the head 348 which presses the gasket 350 uponthe flange I06 of the blank with a pressure of large magnitude, thus forming an effective seal at the open end of the blank. Any leakage which may occur from the interior of the blank tends to increase this force differential and accordingly increases the pressure upon the extremity of the blank preventing continued leakage. sure of 300 pounds per square inch in the blank, a load of 6,000 pounds may be exerted on the flange by suitably proportioning the parts referred'to, thus tending to insure sufficient pressure with-in the blank to cause it to hug the dies when they are closed. 7

'As best shown in Figs.- 5 and 6, the breach block closed position by a latch device which includes a vertical cylindrical bar 358 journaled in bearings 360 mounted on the flange 308 of the cross head 3I2. This bards provided with an axially extending V-shaped groove in its surface and it is provided with an outwardly extending radial pin 362 by which it may be rotated to bring the V-shaped groove into registration with a protruding edge or lip portion 364 on the free side of the breach block. Adjacent the projecting lip 364 of the breach block is a recess 366 in which the cylindrical portion of the bar 358 is received when the latter is held in locking position by the spring 368 engaging the pin 362. The breach block may be unlocked and swung to open position, shown in dotted lines in Fig. 6, by moving the pin 362 against the tension of the spring 368 and so rotating the bar 358 in a counterclockwise direction to allow the projecting lip 364 on the breach block to pass by the groove in the bar 358.

In operation, either. the upper or lower die holders may be moved so as to bring the dies together, but the lower die holder 250 is preferably lifted vertically upward with substantial force by mechanism (not shown) of the character customarily used in die forming operations. A tubular,blank I I2 of the type shown in Fig. 1, having a flange I06 on its open end is heated to a workable temperature in any suitable manner and is lifted, preferably by tongs inserted in the, open end of the blank, and inserted through the cen-' tral opening in the replaceable collar 332 while the cross head 3I2, lower die holder 250 and upper die holder 266 are in the relative positions shown in Fig. 11, and while the breach block 338 is open. In order to obtain uniformity of final product and insure optimum conditions of balance in the finished product, the heavy side of the blank, if any, as preferably determined and marked, in previous operations is positioned on the centerline of thedies which form the flat face I IN) of the blade, these being the lower dies 216 and 218, as shown. The blank "-2 is inserted through the central opening of the collar 332- until the flange I06 thereof engages the outer side of the collar and then the breach block 338 is swung to a closed position with the boss of the head 348 of the bellows 346 extending into the open end of the blank, the gasket 350 being located between the flange I06 and the head 348.

The cross head, which is yieldably held in an ele- In practice, with the presthough it may be vated position by the springs 328, positions the blank in registration with the recesses 218 and 219 of the dies 216 and 211, and holds the blank out of contact with the dies and their supporting structure so as to prevent pre-cooling of localized areas of the blade, as previously mentioned, al-

that, at least before the breach blade being more or less loosely held in collar 332 may sag so as to touch the die at its tip, but this may not be harmful as the previously described thicker wall at the tip may prevent dangerous pro-cooling during the short period of contact if any. Furthermore, as preblock is shut, the

vent the extreme tip of the blade, which is subpressure of -ing movement of the cross head in the die closing 15 jected to the greatest bending efiects in the blade during formation, from splitting open even though it may become cooled to a slight extent.

Before the lower die holder 250 and die 216 are urged upwardly to form the valve 354 is opened so as to admit air into the bellows 346 and to supply'air to the interior of the tubular blank. The pressure in the interior of the bellows is applied directly on the inner side of thehead 348, holding the head in air sealing 25 relation against the flange I06 of the blank. A

300 pounds per square inch is preferably employed where a blank of usual size is made of the ordinary range of low carbon steels and this pressure is preferably. substantially immediately built; up in the blank so as to internally support the latter and to hold all portions of its wall in contact with the surfaces of the recesses in the dies when the lower die is urged upwardly from the position shown in Fig. 11. The lower die, in moving upwardly, first engages the blank and rapidly moves it, together with the cross head 3I2, upwardly against the weight of the blank and the force of the springs 328 until the dies 216 and 211 contactwitheach other and the blank which then assumes its desired blade shape in the depressions 218 and 219 between them. The flanged end of the blank, of course, constantly maintains its engagement with the head 348 duroperation. The closing. movement of the dies is so rapid that the dies contact the entire blank at as near the same timeas possible. This is desirable in order to avoid unequal chilling which might occur if there was, die contact at one point before another. This rapid and complete contact makes it possible to act upon the blankwhile all the metal is at a temperature to be readily shaped.

As the blank cools and shrinks its tapered end is free to "contract longitudinally in the tapered portions of the die recesses. The other end portion of the blank, however, is allowed to move "inwardly with respect to the dies against the action of the springs 324 .cross head 3I2, upon which the flange I06 of the which yieldably hold the blank 2 bears, in spaced relation to the adjacent ends of the die holders. In this manner, setting up of internal strains in the propeller blade during cooling thereof is minimized.

The dies and die holders may be protected from overheating by repeated contact with successive blanks, when used continuously in such pressing operations, by circulating a cooling medium through the passages 258 in the lower die. holder and 282- in the upper die holder. As previously mentioned, the provision of such cooling medium circulating passages further adapts the dies and die holders for use in a preferred subsequent quenching operation, as previously mentioned.

theblank to blade shape, 20

When the pressed blank in the dies has cooled suflicientlyto insure its retainingits now bladelike form, which will ordinarily be after a period of about one minute, the valve 354 is closed, the air is released from the interior of the blade, and the breach block 338 is swung back, and the blank, which is nowtransformed to a blade, is

removed, the notches 336 in the collar 332 functioning to take care of the increase in lateral dimensions of the blade as compared to corresponding dimensions in the blank.

Blades thus received from the dies are checked for ,length, and are then subjected to a suitable cleaning treatment to remove all paint and scale from the outside of the blade. This cleaning operation may be conveniently accomplished in any suitable and convenient manner.

While the blades thus formed are, for the most part, in commercially acceptable form, I find it desirable in order to make a more perfect product, to subject them to a heat treatment. This may be suitably accomplished by suspending each blade byits flange l 06 in any suitable furnace and there subjecting it to a heat soaking process for a suflicient length of time to evenly diffuse the carbides in the metal when carbides are present therein, or for a sufficient length of time to effect other desirable changes in the structure of the metal. The length of this soaking treating, as well as the temperature at which it is carried on will, of course, vary according to the particular metal of which the blade is formed, but for low carbon steels I have found that soaking the blade for approximately thirty minutes at a temperature in the neighborhood of 1625 to 1675 degrees Fahrenheit will sufiice. This same soaking treatment not only evenly diffuses the carbides in the metals, with other usual eifects to the structure thereof but, furthermore, relieves any strains that may have been set up in the metal in the die-pressing operation.

The blade is now removed from the furnace and may again be placed while at high heat within the same dies just described, or equivalent dies, which are closed, andthe blade is then subjected internally to air pressure as previously described. Air pressure in the neighborhood of 300 pounds per square inch is found to be satisfactory, although pressure of either above or below this figure, preferably above; may be employed as well. As before, a complete and rapid closure of the dies is desirable to produce the best result. This treatment not only forces out any small depressions or irregularities in the surface of the blade that may have failed to disappear in the original pressing operation, and not only'will straighten the blade if the same has become warped at all in the soaking treatment due to the relieving of.

but, more important, the

the strains in the metal air under pressure may force all portions of the blade surface into contact with the surfaces of the depressions of the dies, and in doing so causes a chilling of the metal of the blade and prevents separation and segregation of the carbides in the metal thereof, or other undesirable changes in the structure of the metal. At the same time that the main body portion of the blade is being chilled in the dies, a spray of water may be directed onthe flange I 06 thereof to cause a like effect. A period of two minutes in the closed dies will usually be found ample to effect the desired chilling of the blade. While this operation of putting the exterior walls of the blade into contact with the relatively cold walls of the dies is a chilling operation on the blade, I prefer to call it a die-quenching operation; since the results are in all ways analagous to immersing hot steel in a cooling liquid.

This die-quenching effect on the blade serves the same purpose as conventional quenching treatments, and, may be intensified, modified and/or-controlled in several ways, one of which is by the provision of water passages such as 258 and 292 in the die supports 250 and 256 each provided with suitable inlets 260 and 294 respectively, and suitable outlets 262 and 296 respectively. This, or an equivalent method of cooling the dies may be found to be desirable if not essential where the time element between the removal of one blade and the insertion of the next is limited, but it will be recognized that in any case the main requirement is an adequate temperature difference between the dies and the work to effect the proper quench, regardless of the method of obtaining such temperature difference. It will be obvious that it is possible to obtain any degree or rate of cooling to correspond to any degree or type of quench in various ways such as by varying the rate of passage of a multiplicity of blades through the dies, by varying the temperature of the dies themselves by either varying the rate of the cooling fluid passing through them or the temperature of such cooling fluid, and further by varying the temperature of the blank itself. Thus a quick, simple and economical method of quenching the blank is provided.

Instead of relying solely upon a spray of water to cool the flange end of the blade during the quenching operation, as above described, it may be desirable to so modify the die apparatus as to permit a more accurately controlled cooling of the flange end of the blade. This may be conveniently accomplished by using the lower and upper die holders 250 and 266, their respective dies 216 and 211 and thepalr of forwardly extending parallel plates 298, shown in Figures 5 to 12, inclusive, in conjunction with the lower and upper cross head sections 310 and 312, respectively, shown in Figs. 13, 14, and 15. The cross head sections 310 and 312 are provided with side flanges 314- and'316, respectively, which are located between the ends of the die holders 250 and 266 and the cleats 302 mounted on the front edges of the plates 298, as previously described. The cross head sections 310 and 312 are secured against vertical displacement from the lower and upper die holders with which they respectively register by dowel pins 318 mounted on the cross head sections and fitting loosely in cooperating apertures in the ends of the die holders. The loose fitting relation of the dowel pins in their apertures permits the sections to move axially of the die holders and the sections are yieldably retained in spaced relation to the ends of the die holders by the same spring shoes 318 and springs 324, as described'in connection with Figs. 5 to 12, inclusive, and which normally hold the forward edges of the flanges 314 and 316 of the cross head sections against the cleats 302 on the plates 298. The weight of the lower cross may be sufficient to keep it from rising from the lower die holder and it may not be necessary to provide the dowel pin 318 therefor.

Formed in the cross head sections 310 and 312 are complementary, semi-cylindrical recesses 38' and 382 in which-are seated semi-cylindrical tuhead section 310 a apmpoe bular ring segments :04 and are having cooling mifidium passages 388 and 390, respec vely. The ll g segments 384 and 385 are provide with complementary seats 39? and at for receiving the root end portion or shank of the propeller blade and they are detachably held in place. on the cross head sections 310 9.net 312 by screws $98. The ring sections 384 and 386 are provided with inlet apertures 39b and outlet apertures Gilt for petting acooling medium, such as water, to be circulated through the passages tdt'and ttll. Formed'on the side flanges tit and Mt oi the v right hand side of the cross head sections tit ores.

and hit are hinge elements Md and tilt 'on which .a breach block W (see Fig. id) is swingably mounted, substantially in the manner illustrated in Fig. 6. The breach block tilt and the bellows or sylphon tit which it carries, are substantially identical in construction to the breach bloclr tit and the bellows t lt whichhas been described in detail in connection with Flash, '2, and h. The

bellows i communicate with an inlet pipe or nipple i1 oi a valve tit which is provided for controg the admission of air to the interior oi the bellows and to the interior oiv a propeller initially supportedby, its shank so as to be held out oi contact with the dies as shown in Fig. ll. since the rings ttt and ttt are not supported by'-.

- the springs ttt. The hot blade may then be layed directly on the lower die and the diesclosed so suddenly and rapidly that uniform contact over the entire surface of the blade me; be procured as promptly as possible.

in Figs. l6, l7, and 18 a slight modification of the previously describeddie structure is shown in which the die depressions in the dies are so termed as to conform exactly in size, shape and contour throughout with that desired in the huished blade instead of having the outer stages oi the depressions longer and wider than the blades as described in connection with the previous fig- Since the only changes over the structure previously "described is solely in connection with the dies tilt and l'lhall the parts indicated in a Figs. 16, 1'7, and it, with the exception of the dies themselves, bear theisame numerals as in Figs. 5 to 12, inclusive, and the dies themselves bear the same'numerals except that they carry the subletter "a". Accordingly, it will be noted that the dle depressions lids and 279s conform. exactly in size, shape and contour with the desired size,

shape and contour of the desiredblade ltd; it,- of course, being understood that the perimetrical dimeirisions of the.conibined depressions tits and 65 same stage of length before the blank is pressed Hon taken in a plane perpendicular to the longitudinal axis of the blade at any stage oi the length thereof; are substantially exactly equal to the perimetric dimensiOn's of the blank at the toblade shape, so that no expansion of or crowding in or the metal of the blank occurs during the pressing operation, but rather the metal oi- T theblank is simply bent into the desired shape.

It might be noted that. in this case the nipple is l n is omitted from the end or the blank, although *2; l

' F x it will be apparent that this nipple may be providedii desired in this case and the depressions 318a and 219s modified sufliciently to permit its reception.

Formal changes may be made inthe specific embodiments of the invention described without departing from the-spirit and substance of the broad invention, the scope of which is commensurate with the appended claims. I claim:

i 1. Forming apparatus including a pair oi relatively movable die holders, a pair of dies, one

mounted in each holder, and a support for posh,

tioning a piece of worlr in operative; relation with respect -to said dies including a wort: holder shittable in the direction of relative lorming movement of said dieholders and including means for initialy so positioning said worlr holder as to retain work held thereby in spaced relation to both of and dies until commencement oi their lormins operation and to accommodate movent of said worlr holder and work held thereby ill the direction of relative forming movement oi said die holders during the forming operation of the latter.

2. Forming apparatus including an upper stationary die holder, a lower vertically movable die holder, a pairoi dies, one in each oi said die holders, a vertically shiftable cross he located in close proximity to said dies and having an opening for receiving the end portion of a blanlr, and

yieldable members normally supporting said cross headin an elevated position sons to ret said blank in spaced relation to said dieswhen the latter are spread apart.

- 3. Forming apparatus including a pair oi relatively movable die holders, a pair of dies, one

mounted in each holder, a support shittable bodily laterallyand lengthwise of said dies in a direction toward one end thereof for positioning a blank between said dies, and yieldable means normally urging said support outwardly toward in a predetermined spaced position from the adjacent ends ot said dies so as to accommodate resiliently. restrained longitudinal contraction oi said blanlr 4 upon cooling.

l. Forming apparatus including a pair oi relatively movable die holders, a ir oi dies, one

mounted in each holder, a support located at one end of said r oi dies for positioning a blanlr therebetween, said support being shiitable length-- wis;e oi said dies and shiltabie'in the direction of the relative movement thereof, yieldable means ior holding said support in a predetermined location with respect to the spread apart positions of said dies so as to prevent contacting of said blanh therewith, and means io'r yieldably holding said support in spaced relation to the adjacent 'ends of said dies so as to permit longltual contraction of said blank upon cooling.

5.. Forming apparatus including, an upper stationary die holder, a lowervertically vable die holder, a pair of dies, one in each oi said die holders, a cross-head sh'iitable vertically d lengthwise with respect to said dies and die holders and havingan apertureior receiving a bio, springs yieldably supporting said. cross-head in an elevated position so as to retain said blank in spaced relation to both of said dies when the latter are spread apart, and resilient shoes'bearing between said cross headand the adjacent ends or said. die holders for yieldably holding said cross head inspaced relation thereto so 'as to per- 'mit, lengthwise contraction of said blank upon cooling.

'6. Formin appcranis mai s; sna er tionary die holder, a lower vertically movable die holder, a pair of dies, one in each of said die holders, a vertically shiftable cross-head located in close proximity to the open ends of said dies and having an opening therein, a replaceable adapter detachably mounted in said opening for receiving an end of a blank and resilient members yieldably retaining said adapter intermediate the spread apart portions of said die holders so as to prevent premature contacting of said blank with said dies.

'7. Forming apparatus including an upper stationary die holder, a lower vertically movable die holder, a pair of dies, one in each of said die holders, :2. cross-head located in close proximity to the open ends of said dies and shii'table bodily and laterally and lengthwise thereof, means on said cross head for supporting a blank, and resilient means yieldably holding said cross head in spaced relation to the open ends of said dies and adapted to accommodate resiliently restrained longitudinal contraction of said blank upon coolmg. i

\ 8. Propeller blade forming apparatus including a pair of die holders, a pair of dies, one in each die holder, a support adjacent one-end of said pair of dies having an opening for receiving the open end of a tubular propeller blade blank and adapted to independently support the latter from the open end portion thereof, and a member swingably mounted on said support including means for registering with said opening forming a communicative connection between the interior of said blank and an external source of fluid pressure for internally supporting the blank during compression thereof to blade shape.

9. Propeller blade forming apparatus including a pair of die'holders, a pair of dies, one in each die holder, a support adjacent one end of said pair of dies having an opening for receiving the open end of a tubular propeller blade blank, a breach block swingably mounted on said support, and a member carried by said breech block for forming a communicative connection between the interior of said blank and an external source of fluid pressure for internaliy'supporting the blank during compression thereof to blade'shape.

10. Propeller blade forming apparatus including a-pair of die holders, a pair of dies, one in each die holder, a support adjacent one end of said pair of dieshaving an opening for receiving the open end of'a tubular propeller blade blank, a' breach block swingably mounted on said support, and a yieldable member carried. by said breach block for forming a communicative connection between the interior of said blank and an external source of fluid pressure for internally supporting the blank during compression thereof to blade shape.

11. Propeller-blade forming apparatus including a pair bf die holders, a pair of dies, one in each die holder, 2. support adjacent one end of said pair of dies having an opening for receiving the open end of a tubular propeller blade blank, a breach block swingably mounted on said support, and a sylphon carried by saidlbreach block for forming a communicative connection between the interior of said blank and an external source- 01' fluid pressure for internally supporting the blank during compression thereof to blade shape.

12. Propeller blade forming apparatus including a pair of relatively movable die holders, a

- pair of dies, one in each of said holders, 9. shiftable support located at one end of said pair of dies for positioning a tubular propeller blade blank therebetween, means for'yieldably holding said support in a predetermined position relative to said dies so as to retain said blank out of contact with said dies when the latter are spaced apart, and means on "said support for forming a communicative connection between the interior, of said blank and an external source of fluid pressure for internally supporting the blank during forming thereof to blade shape.

13. Propeller blade forming apparatus including a pair of die holders, 9. pair of dies, one in each holder, spaced protruding elements on an end of one of said die holders, a cross-head shiftably mounted between said elements having an opening for receiving the open end portion of a tubular propeller blade blank, members yieldably holding said cross head in spaced relation to said i die holders for permitting inward movement of the open end portion of said blank during shrinking thereof upon cooling, and means on said cross head for forming a communicative connection,

between the interior of said blank and an external source of fluid pressure for internally supporting the blank during compression thereof to blade shape.

25 14. Propeller blade forming apparatus includ- I member carried by said breach block for forming a communicative connection between the interior of said blank and an external source of fluid pressure for internally supporting the blank during compression thereof to blade shape.

15. Propeller blade forming apparatus including a pair of die holders, a pair of dies, one in each holder, spaced protruding elements on an end of one of said die holders, 8. cross head shiftably mounted between said elements having an opening for receiving the open end portion of a tubular propeller blade blank, a breach block swingably mounted on said cross head, means for releasably holding said breach block in a closed position, a resilient member mounted on said breach block including a head portion registering with the open end of said blank and having an aperture in communication with the interior thereof for supplying a gaseous medium thereto, and means communicating with said resilient member and a source of pneumatic pressure.

16. Propeller blade forming apparatus includeach holder, spaced protruding elements on an end of one of said die holders, 8. cross head shiftably mounted between said elements having an opening for receiving the open end portion of a ing a pair of die holders, a pair of dim, one in 60 tubular propeller blade blank, a breach block 65 swingably mounted on said cross head, means for releasably holding said breach block in a closed position, an expansible member mounted on said breach block including a head portion registering with the open end of said blank and having an aperture communicating with the interior thereof for supplying a gaseous medium thereto, and means communicating with said expafisible member and a source of pneumatic pressure, the

side oi. saidhead adjacent said blank being smaller in area than the other side of said head so as to create a force diilerentia for holding said head in a sealed relation on the pen end of said blank.

17. Forming apparatus including a pair of relatively movable die holders, each having a cooling medium circulating passage therein, a pair of dies, one in each. die holderfa support for a piece of work located at one end of said dies shittable bodily in the direction of relative movement of said die holders while supporting a piece of work therebetween, and means normally yieldably holding said support in a predetermined position with respect to said dies so as to retain the work out of contact with the latter when said dies are spread apart. v

18. In forming apparatus, a support including a cross head having a seat therein for receiving the open end of a tubular blank, a member adapted to be releasably secured on said support in spaced, substantially parallel relationship to said cross head, and a bellows mounted on said member including a head portion having an air passage therethrough and receivable by the open end of said blank for forming a communicative connection between the interior or said blank and a source of pneumatic pressure. I

19. In forming apparatus, a support including a cross head having a seat therein for receiving the open end of a tubular blank, a breach block swingably mounted on'said support in spaced relation to said cross head, and means carried by said breach block and communicating with a source of pneumatic pressure for forming a communicative connection between the interior of said blank and said source oi pressure as said breach is swung to a closed position.

20. Apparatus for making propeller blades from a tubular blanhii'ncluding a pair of relatively movable die holders, a pair of dies, one mounted in each die holder and each die including a replaceable section, a member shiftable laterally and longitudinally with respect to the length of said dies for supporting a blank by attachment to its root end, and means normally yieldably urging. said member into outwardly spaced relation to one end of said pair 01 dies, adaptedto accommodate longitudinal contraction oi said blank upon cooling.

21. Apparatus for making a propeller blade from a tubular blank including a pair of die holders each having cooling medium circulating passages therethrough, a pair of dies one in each of said die holders, a member at one end or said dies for supporting the root end of said blank and having cooling medium passages therethrough, and means on said support ior forming a communicative connection between the interior of said tubular blankand an external source of fluid pressure.

22. Apparatus for making a propeller blade from a tubular blank including a pair of die holders, each having cooling medium circulating passages therethrough, a pair or dies, one in each of said die holders, a pair of cross head members each movably mounted on one end of said die members having complementary recesses for receiving the root end portion and flange of said blank and each having a cooling medium passage surrounding its recess, and yieldable shoes normally holding said cross head members in spaced relation to the adjacent ends of said die holders.

23. Apparatus for making a propeller blade from a tubular blank including a pair of die holders, each having coolingmedium circulating passages therethrough, a pair or dies, one in each of said die holders, a pair of cross head members each extensively mounted on one end of said die holders having complementary recess for receiving the root end portion and flange of said blank and each having a cooling medium passage surrounding its recesses, yieldable shoes normally holding said cross head members in spaced relation to the adjacent ends of said die holders, and means mounted on said cross head sections for forming a communicative connection between the interior of said tubular blank and an external source of fluid pressure.

24. Apparatus for forming a hollow article of irregular contour from a hollow blank including a pair of die holders, each having cooling medium circulating passages therethrough, a pair of dies, one in each of said die holders, a member at one end of said dies for, supporting the root end of said blank and having cooling, medium passages therethrough, a breach block swingably mounted on said member, and-means carried by said breach block for forming a communicative connection with the open end of said blank and a source oi' fluid pressure upon closing of said breach block so as to internally support said hollow blank. g

25. Apparatus for making a propeller blade from a tubular blank including a pair of die holders, each having cooling medium circulating passages therethrough, a. pair of dies, one on each of said die holders, a pair of cross head members each movably mounted on one end of said die holders having complementary recesses 1'01 receiving the root end portion and flange of said blank and each having a cooling medium passage surrounding its recess, yieldable shoes normally holding said cross head members in spaced relation to the adjacent ends of said die holders, a breach block swingably mounted on said cross head members, and expansible means carried by said breach block for forming acomrelation to said cross head, and means for yieldably holding said cross head against movement toward the open ends of said diesincluding members compressible during longitudinal thermal contraction of ,said blank for releasing the strain thereon.

2'7. Forming apparatus including a pair of relatively movable die holders, a pair oi dies, one mounted in eachof said die holders, a. cross head located at an end of said dies and shiftable bodily in the direction of relativemovement of said die holders, said cross head being provided said blank from one end thereof in a fixed with means for receiving one end of a blank and supporting the latter between said dies, and means for yleldably holding said blade receiving portion 01 said cross head in misalignment with the closed positions oi. said dies to retain said blank out of contact with said dies when said die holders are spread apart.

28. Apparatus for forming a tubular article having an open extremity including a support- 75 Iii ing structure, a pair of dies supported thereon, a member on saidsupporting structure adjacent one end of said dies including means for supporting a blank having an open extremity from the end portion of said blank adjacent its open extremity, a breach block swingably mounted on said member, and an element carried by said breach block for forming a communicative connection between the interior of said blank and a source of fluid pressure for urging the exterior of said blank against said dies.

29. Apparatus for forming a tubular article having an open extremity including a supporting structure, a pair of dies supported thereon, a member on said supporting structure adjacent one end of said dies including means for supporting a blank having an open extremity from the end portion of said blank adjacent said extremity, a breach block swingably mounted on said member, means for releasably holding said breach block in a closed position, and an expansible element carried by said breach block for forming a communicative connection between the interior of said blank and an external source of fluid pressure, said element being adapted to expand under the influence of said fluid pressure for maintaining a tight seal between the contacting portion thereof and said blank.

30. Apparatus for forming a propeller blade from a hollow metal blank comprising dies having die depressions which at an intermediate point in their length correspond to the size of the corresponding part of the blade while leaving the tip end free to slide therein when contracting while cooling, and associated means for holding the hub end of the blade adapted to give to allow the hub end to move in when the blade contracts during cooling.

31. Apparatus for forming a propeller blade from a hollow metal blank comprising dies having depressions which at an intermediate point in their length correspond to the size of the corresponding part or the blade while leaving both the tip end and the hub end of the blade free to slide therein when contracting while cooling.

32. Apparatus for forming a hollow article having an open extremity including a. supporting structure, dies supported thereon, a member located at one end of said dies andshiftable toward the latter including means for receiving an open extremity of a hollow blank and supporting the latter from the end portion thereof adjacent said open extremity, means yieldably holding said member in a predetermined spaced rela tion to the adjacent end of said dies, a breach block swingably mounted on said member, and

means on said breach block registering with the open extremityof said blank for forming a communicative pnnection between the interior thereof and an external source of fluid pressure.

33. Forming apparatus including a pair of die holders each having a cooling medium circulating passage therein, a support for position ing a blank betweensaid dies, said support being 1 in the direction of movement of said die holders and located at one end of said die holders and dies including means .for initially supporting a piece of work from an end portion thereof located externally of said dies, and yieldable means acting upon said support for holding the latter in a predetermined position with respect to said dies so as to retain the work out of contact with said dies when they are spread apart.

35. Means for forming a propeller blade from a hollow metallic blank of generally circular section comprising a plurality of die members having matching depressions in the opposed faces thereof, the perimetric dimensions of a transverse section through said matching depressions over 'a portion of the length thereof corresponding substantially exactly with the perimetric climansions of a corresponding section of the blank to be received therein, and the perimetric dimensions of a transverse section through said matching depressions over another portion of the length thereof being materially greater than the perimetric dimensions of a corresponding section of said blank.

36. Means for forming a propeller blade from a metallic blank comprising a plurality of die members having matching depressions in opposed faces thereof, the size, shape and contour of a section taken through said matching depressions over a portion of the length thereof being substantially identical to the size, shape and contour of a corresponding section taken through the desired finished blade, and the size of a section taken through said matching depressions over another portion of the length thereof being substantially greamr than the size of a corresponding section taken through the desired finished blade.

3'7. Means for forming a propeller blade from a' metallic blank comprising a plurality of die members having matching depressions in opposed faces thereof, the size, shape and contour of a section taken through said matching depressions over a portion of the length thereof being substantially identical to the size, shape and contour of a corresponding section taken through the desired finished blade, and the size of a section taken through said matching depressions over another portion .of the length thereof being substantially greater than the size of a corresponding section taken through the desired flnished blade, but of substantially the same thickness as the last mentioned section.

38. Apparatus for pressing a hollow metallic blank to propeller blade shape comprising a pluralityof die parts having matching depressions in their opposed faces generally conforming to the size, shape and contour of the desired finished blade, 9. section through said matching depressions over the root portion of said blade conforming substantially exactly to that desired in a corresponding section of the desired finished blade. and those portions of said depressions adapted to form the tip end portion of the finished blade being wider and longer than the corresponding portion of the desired flnished blade.

39. Apparatus for pressing a hollow metallic blank to propeller blade shape comprising a plurality of die parts having matching depressions in their opposed faces generally conforming to the size, shape and contour of the desired finished blade, 8. section through said matching depressions over the root portion of said blade conforming substantially exactly to that desired in a corresponding section of the desired finished blade, and those portions or said depressionsadapted to form the tip end portion of the finished blade having opposed wall portions generally conforming to the desired contour of the major portion of the opposite faces of the corresponding portion 1y movable die members having matching depres sions therein adapted to receive said blank and the walls of which depressions are adapted to control the cross sectional shape of the blank when pressed to blade shape thereby, each of said members comprising at least two parts separable longitudinally of the corresponding depression intermediate the ends of the depressions, the size andcontour of the matching depressions in said parts at one portion of said members contorming substantially exactly to that desired in the corresponding portion of the finished product, and the size of the matching depressions in said "parts at another portion of said members varying from that desired in the corresponding portion of the desired finished product. v

41. Apparatus for pressing a tubular blank to propellerblade shape including a pair of relatively movable die members having matching depressions therein adapted to receive said blank and the walls of which depressions are adapted to control the cross sectional shape or the blank dies when pressed to blade shape thereby, each 01' said members comprising at least two parts separable longitudinally of the corresponding depression intermediate the ends of the depressions,

the size and contour of the matching depressions 5 in an opposed pair of. said parts for the root end portion of the blade conforming substantially to the size and contour desired for the root end portion of the finished blade, and the size of at least a portion of the matching depressions in v another opposed pair of said parts adapted to iform the tip ,end of said blade being greater than the dimensions desired in the tip end of the finished blade. v

42. Means for forming a propeller blade from a hollow metallic blank of generally circular section, 01 tapered formation and having the smaller end thereof closed and provided with an axially extending nipple, comprising a plurality of die members having matching depressions in' opposed faces thereof, the size. shape and contour of a section taken through said matching depressions. over at least a. portion of the length thereof being substantially identical to the size, shape and contour of a corresponding section taken through the-desired finished blade, the length of said depressions being greater than the corresponding length desired in the finished blade whereby to provide clearance for said nipple during pressing of said blank toblade shape between said JOHN SQUIRES.

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