US1082199A - Manufacture of hollow bodies. - Google Patents

Description

B. KNAEBEL. MANUFACTURE OF HOLLOW BODIES. APPLIOATION FILED JAN. 4, 1910.

Patented Dec. 23, 1913.

' UNITED STATES PATENT OFFICE.

BENEDIK'I KNAEBEL, OF DUSSELDORF, GERMANY, ASSIGNOR '10 RHEINISCHE METALL- WAAREN- UND MASCHINENFA'BRIK, OF DUSSELDORF-DERENDORF, GERMANY.

MANUFACTURE OF HOLLOW BODIES.

Specification of Letters Patent. Patented Dec. 23, 1913,

Application filed January 4, 1910. Serial no. 536,309.

To all whom it may concern Be it known that I, BENEDIKT KNAEBEL,

chief foreman, a subject of the German Emperor, residing at 3 Geistenstrasse, Dusseldorf, Germany, have invented new and useful Improvements in the Manufacture of Hollow Bodies, of which the following is a specification.

This invention relates to improvements in the manufacture of hollow bodies, and

more particularly of cartridge cases, from,

solid prismatic or cylindrical blocks of copper alloys, and it involves certain improvements on the process for the manufacture of cartridge cases of brass or other alloy of copper described in the specification of the application for patent in the United States filed December 15, 1905, the serial number of which application for patent is 291,938. In the said process for the manufacture of cartridge case a hollow blank is first formed by a single pressing operation from a red hot solid prismatic or cylindrical block of an alloy of co per which may be termed cartridge brass, and from the cup shaped blank thus produced the cartridge case is made. It has been explained in the said specification that the base of the said cartridge. case is formed with any desired cross-section which must be provided for beforehand, and which is necessary for example for shaping a flange around the base and a detonator chamber, the thickness being otherwise held within the limits required in practice.

By reason of the sensitiveness of the materials under treatment (brass containing about 65 to 72 per cent. of Cu and about 35 to 28 per cent. of Zn) when worked in a state of red heat, it is imperative, that the pressing of the blocks be always effected at a uniform speed and at the correct temperature of the into the die and removing the pressed blank from the same. Accordingly the tools must be so constructed, that the block can not be placed edgewise into the die and that it is not necessary to center the same after once placmg it into the die, which operation would cause an objectionable delay. As the mass of metal of the cylindrical portion of the cartridge case is small as compared to its diameter, and as the whole mass of metal of the case including its base is small as compared to the space occupied by the car-' tridge case, the transverse'dimensions of the blocks subjected to the process are always comparatively large, while their heights are comparatively small, the former being generally a multiple of the latter. WVhen placing such blocks of cylindrical or prismatic cross-section into the die, their position with in the latter is frequently inaccurate in that they are sometimes located angularly to the axis of the die. The reason for this is that, when using a die the axis of which is vertical, it is necessary to drop the block into the hollow of the die which on account of the height of the blank to be made is compara tively long, or when using horizontal dies, the block always tends to assume an incorrect position, even if it has beforehand been placed in correct position.

One of the objects of the present invention is to provide a pressing apparatus of such a construction, that the block when being inserted into the die can assume only a position centrally of the die and coaxially with the axis of the pressing apparatus. WVith the block thus positioned, the flow of metal in the pressing operation to form the side wall of the hollow of cup-shaped blank is uniform on all sides of the die, and the said side wall of the resulting blank is thus of uniform strength over its entire area and its axial dimension or height is also uniform around the whole circumference of the blank.

A die constructed in the manner described hereinafter is advantageous also in this respect, that the pressing operation can be continued without interruption, until the tools become so hotthat' they must be cooled by water or in a similar way.

A further object of the invention is to provide a process whereby the block is held under pressure, and as far as poss ble through its whole mass, from the beginnlng of the pressing operation to the end thereof when the shaping of the block has been completed. It is impossible to forge and press the red hot cartridge brass used in the manufacture of the cartridge cases, if the forging or pressing force acts on parts only of the block, and if the metal can flow out of the area of the pressure so as to cause a flow of the metal within parts of the block which are not subjected to the pressure. As far as the pressure is effective within the block, the metal remains homogeneous and of coherent structure. But within the adjacent portions of .the metal which are subjected to the indirect influence of the pressure the structure of the metal is changed, it is rendered less compact, and it is torn or broken. For this reason, the block subjected to the process describedin the aforesaid prior application is solid and of prismatic or cylindricform and its transverse dimension, that is its diameter or diagonal, is smaller or at least not larger than the transverse dimension of the blank to be formed therefrom. In a certain degree, the block is thereby subjected to a uniform pressure throughout its mass because when making articles of the character described in the said prior application only a very small amount of metal projects beyond the surface area of the punch, and the said amount is particularly small, if the crosssection of the block is of square cross-section. In this case the block projects beyond the surface area of the punch a slight distance at its corners only. Also in the process described in the said application the pressure acts through the whole of the mass of the block, because the punch is rounded at its margin to correspond to the rounded form of the hollow of the cartridge case. As soon as the punch strikes the metal and the shaping operation is started, lateral and angular components of the pressure are directed through the mass of the block, and as the flow of the metal proceeds, the direction ,of the said components gradually approaches the horizontal, so that the pressure acts on the part of the die where the final form of the cylindrical part of the case is formed within the annular space formed by the punch and the wall of the die, that is to say, until the relative position of the punch and die is attained in which the said annular space is formed.

The object of the present improvements is to provide a process in which the effect of the pressure described is further assured, and by which the pressing operation is performed in a better way. For this purpose the transverse dimension, that is its diameter or diagonal, of the block to be transformed into the hollow blank is made not larger than the diameter of the punch. In other words, the effective cross-sectional area, or the area of the horizontal projection of the effective pressure surface of the punch is substantially not less than the cross-sectional area of the block. \Vhen thus reducing the diameter of the block the pressure is under any circumstances at once exerted through the whole of the mass of the block, and the latter is more easily transformed by the said pressure into the hollow blank with its thin walls. In this operation the metal is first caused to flow so as to fill out the cavities of the die, and while still flowing it is transformed into its final shape while undergoing the greatest change of the form of its cross-section. It is well known, that when. thus making use of the flowing property of the metal, the forcible transformation of the form of the block takes place more easily. This is particularly important in the present case, because otherwise in the manufacture of cases for ordnance cartridges of higher calibers considerable forces would be necessary, while when reducing the cross-sectional area of the block the said considerable transformations can be effected by means of,comparatively small forces,

For the purpose of explaining the invention more in detail an example embodying the same has been described hereinafter, reference being had to the accompanying drawing forming a part of this specification.

In said drawing-Figure l, is a vertical cross-section of a pressing apparatus showing a block within the cavity of the die and the punch in its position just before the pressing operation, Fig. 2, is a similar crosssection of an apparatus illustrating amodification of the apparatus and showing the punch and other parts in their positions at the end of the pressing operation, and Fig. 3, is a horizontal cross-section of F ig. 2.

The same letters of reference have been used in all the views to indicate corresponding parts. I

Referring to the example illustrated in the drawing, a die a consisting of a block of steel is formed with a cavity which is of slightly less depth than the block d to be subjected to the pressing process. Accordingly the said block when placed into the cavity of the die projects with its upper face above the upper face of the die. In the position of the parts shown in Fig. 1, the punch a is located directly above the said block and in contact therewith. Bearing on the upper face of the die and surrounding the punch a ring (Z is provided which is adapted to slide on the punch without having an objectionable play thereon. The block b is either of circular or polygonal (square) cross-section, and its transverse dimension is such, that when being inserted into the die it is guided with its axial sides or its cylindrical surface within the bore of the ring (I, so that it can get into the die only in a perfectly centered position. In order to more easily insert the block into the die the bore of the ring d is formed at its upper end with an outwardly flaring wall. As the cavity of the die is less deep than the block, the latter projects with its upper end beyond the die and into the bore of the ring at the beginning of the pressmg operation, and only when the punch is forced downward and on the metal of the block is itentirely slipped out of the ring. By disposing the ring (Z immediately on the block also the punch is centered relatively to the block and the die to the last moment, provided that the ring d is held in a centered position. In the example illustrated the said centered position of the ring 07 is assured by means of a sleeve 6 surrounding the same and engaging with a concentric flange f the upper part of the die a whereby it is held in centered position. The said sleeve is formed with a bore which is disposed axially of the pressing apparatus, and within the said bore the ring d is adapted to slide in an axial direction. At its upper end the collar 0 is formed with an inwardly projecting flange g, providing a suitable guide for the punch c. In the improved die the pressing operation is performed as follows: lVhilethe punch is in its retracted position shown in dotted lines in Fig. 1, a block I) at red heat is held above the upper aperture formed by the flange g and it is dropped. When thus falling downward it is guided within the bore of the flange g and it falls on the bore of the ring d through which it passes in a centered position, until it arrives in the position shown in Fig. 1 and at the bottom of the cavity of the die in which it still has a centered position. Now the pressing apparatus is started without delay, the punch 0 passes centrally through the guiding portion 9 of the sleeve 6 and it is again guided within the bore of the ring d. As soon as it comes in contact with the block b the pressure is exerted on the latter in the manner described above. The whole block is under pressure and it remains under the action of the said pressure, until the metal reaches the annular space which is being formed by the descent of the punch between the latter and the wall of the cavity of the die. As soon as the metal has passed this annular space the pressure on the same ceases. Simultaneously however the metal forming operation comes to an end, and therefore the metal is not torn or otherwise injured, as is quite common in working metal of a similar character in a state of red heat. Through the annular passage the metal rises around the punch c in the form of a hollow cylinder, and the ring (5 is raised thereby, as is shown in Fig. 2. The entire pressing operation is effected Within a very short time, so that the metal hardly changes its temperature. At the end of such pressing operation the punch a is again retracted and the cup shaped blank slipped off the same by means of the ring ol. Now the guiding sleeve 6 may be removed and the blank taken out of the die. To prevent the ring 03 from dropping downward when the guiding sleeve (2 is removed and the cup shaped blank is taken off the die, an inwardly projecting ring 2' is secured to the lower side of the said sleeve e.

Fig. 2 shows a modification of the construction of the sleeve 6. As shown in the said figure, the sleeve is formed with a lateral opening it of suflicient dimension to permit the removal of the pressed blank by means of a pair of tongs. Therefore it is not necessary to remove the sleeve 6 after each pressing operation. In a similar way the hot block can be inserted into the die through the said opening it, in which case the stroke of the punch can be reduced. The stroke of'the punch required in this case is indicated in dotted lines in Fig. 2.

Having thus fully described my invention, what I claim is:

1. The improved process of manufacturing tubular bodies from alloys of copper, which consists in preliminarily shaping a block of such alloy while llOl] by compression by means of a punch the horizontal projection of whose effective pressing surface is substantially not less in area than the crosssectional area of the block, whereby the block from the beginning of the pressing operation to the end thereof is subjected to the pressure through the whole of its mass, and finishing while cold.

2. The improved process of manufacturing tubular bodies from alloys of copper, which consists in preliminarily shaping a block of such alloy by compression while hot by means of a punch the horizontal projection of whose effective pressing surface is substantially not less than the crosssectional area of the block and while confining the block within a die adapted to hold the block through the whole of its mass under the pressing action of the punch from the beginning of the said pressing action to the end thereof, and finishing while cold.

3. The process of manufacturing tubular bodies from brass which comprises accurately centering a hot block of brass in a die whose depth approximates the thickness of said block, and compressing said block while hot by means of amnch the horizontal projection of whose e ective pressing surface is substantially not less in area. than the cross sectional area of the block, to produce a cups shaped blank having a, side wall of uniform strength.

In testimony whereof I have slgned my name td this'speeification'in the presence of two subscribing witnesses.

BENEDIKT KNAEBEL. [L. 5.] Witnesses:

O'rro'Kfinm, PAUL Mfimm.

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