US2248278A - Method of forming conical shells - Google Patents

Description

y N. MICHELMAN 2,248, 78

METHOD OF FQRMING CONICAL SHELLS v Filed Nov. 4, 1938 6 I I3 I3 I! '3 Fig ,4,

Patented July 8, 1941 *UN-ETED STATES, PATENT *OFFI'CE 2,248,278? H METHOD or FoRMINGooNrcAL SHELLS Nathan Michelman, Bathe. N. Y. Application November 4, 1938, Serial'No. 238,882 (or. 29 1'55 q 1 Claim.

This invention relates to. improvements in methods of and apparatus for forming conical ratus, and operations, particularly when a series of connected conical shells of gradually decreasing size are required. The second of these methods is deficient in that considerable effort is required in the pressing or bending operation to bring the edges of the V'-slit in the tube into abutment, particularly towards the end having the greatest slit width, usually resulting in a distending or flattening of the shell at the zones adjacent and at the slit edges. Further, in this second method, the welding operation along the resulting longitudinal slit line defined by the slit edges, causes an arcuate longitudinal bending of the formed shell requiring a re-heating and repressing or bending of the shell after the welding step to impart the required conical formation.

To obviate these difiiculties and to provide a generally equal distribution of the stresses upon a slit cylindrical shell in the pressing or bending thereof to form a conical column, I have formed an excision in the nature of a slit of gradually decreasing width, but have made the excision of helical or spiral form as it progresses peripherally from end to end of the cylindrical shell. By this slit formation I am enabled in the subsequent pressing or bending operation to provide for a balanced stress or pressure along the length and periphery of the slit cylindrical shell, so that the resulting conical shell will be substantially arouate with respect to its peripheral contour.

These and other advantages, capabilities and features of the invention will appear from the subjoined detailed description of one specific embodiment thereof illustrated in the accompanying drawing, in which Figure 1 is a front view of a cylindrical shell excised in accordance with my invention.

Figure 2 is a front view of the excised cylindrical shell after swaging in accordance with my invention.

Figure *3 is a perspective front elevation of my swaging'frame,

Figure 4 is an end-elevation partly in section of asection'at one end of my swaging frame in application.

Figure 5 is an end elevation partly in section of another section at the other end of my swaging frame in application.

' Referring to thereference characters in the drawing, letter A represents a stock cylindrical shell, excised from end to end to form a helicoidal slit ill of gradually decreasing width, and letter B represents the excised shell of Figure 1 after swaging to provide a frusto-conical shell with the edges of the excision brought into abutting relationship asat II, and after welding to form 'a sealed enclosing unit.

' The pressing or swaging apparatus comprises a framework C, formedof a series of plates 12 spacedly mounted along frame rods iii. The plates l2 have a polygonal outer periphery l4 and are centrally apertured to define an inner periphery l5. The frame rods l3 pass through apertures in plates l2 in the line of the apices of the outer periphery of the plates.

In the framework, a plurality of plates [2a disposed preferably one at each end and one centrally thereof, are provided for service as guideways for the press rods 16. These plates l2a have the same outer peripheral contour but are wider than plates l2, their central aperture being of lesser diameter than that of plates l2. The plates 12a. have formed along their inner periphery I5a spaced right angular guide grooves l1, opposite to and in line with the frame rods B. The press bars I6 which are rectangular in crosssection extend along the length of the framework and rest in and are guided for longitudinal movement in assembling the framework, and. transverse movement intheir pressing action by the side walls of the grooves IT. The grooves H are of such depth that their closed ends are in line with the inner peripheral surface l5 of the plates l2, so that the press bars I6 when set Within the grooves I! of plates I20, rest against the inner peripheral surface I5 of the plates l2. The innermost central aperture of the framework as defined by the press bars l6 extending inwardly of the plates Hat is of sufficient diameter to permit insertion of the slit cylindrical shell shown in Figure 1.

To bring the edges of the excised slit it! of the cylindrical shell A of Figure 1 into abutting relationship indicated as l l in Figure 2, the following steps are followed: a

The framework C is disposed preferably horizontally to rest on one of the polygonal outer peripheral faces of the plates l2 and [2a, and the press bars I6 removed from the grooves ll of the plates IN. The slit cylindrical shell A is inserted in the framework and successively the respective press bars are slid to extend longitudinally into the framework, being disposed within the guide grooves I! of plates I2a and adapted to rest adjacent the periphery of the slit shell, the framework being rotated until all the press bars are in position, thereby providing spaced longitudinal action zones forthe same with respect to the slit cylindrical shell. A series of wedges l8 are inserted in spaced relationship along the respective lengths of the framework between opposing frame rods I3 and press bars it, such wedges being disposed oneor more between each set of plates I2 or [2 and In. The wedges are then driven in the direction of the arrow as the framework is periodically rotated to rest on the respective polygonal faces of the spaced plates I2 and l2a, so as to provide a gradual pressing and bending effect upon the slit cylindrical shell along the longitudinal zones defined along the length of the press bars, which as they are displaced inwardly from their grooves away from the fixed frame rods are caused to press against the peripheral surface of the slit cylindrical shell. progressively along their length away from the frame rods in greater amounts, corresponding t the original wider dimensions of the excision slit being closed, the relative relationship of the press bars I6 and the frame rods l3 at the con- The press bars are displaced such figures the narrow end of the frusto-conlcal shell is formed, and Figure 5, where the wider end is formed.

Since the pressing or swaging is carried out by a progressive driving of the wedges along longitudinal zones of the framework as the same is periodically rotated, a gradual pressure and even stress is applied longitudinally of the tubular slit shell as it is brought to the desired frusto-conical contour, at which time the edges of the slit are in abutment to provide the conformation shown in Figure 2.

When the edges of the slit are brought into abutment the shell is welded while in the frame to substantially seal the slit defined by the abutting edges. The wedges are then driven out, the frusto-conical shell removed from the frame and those sections of the slit abutting edges unavailable for welding by virtue of the proximity of the inner peripheries of the pltaes I2 and I2a are welded to complete the closure along the abutting edges of the helicoidal slit line of the frusto-conical shell shaped in the framework.

It is obvious that various changes and modifications may be made to the details of construction without departing from the general spirit of the invention as set forth in the appended claim.

'I claim:

The method of forming a conical shell from a cylindrical shell, which consists in excising the cylindrical shell to form a helical slit of gradually decreasing Width from end to end of the cylindrical shell, thereafter applying pressure to the cylindrical shell at a plurality of zones to bring the edges of the shell defined by the slit into abutment and thereafter welding the abutting edges to each other.

NATHAN MICHELMAN.

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