US2790227A - Process of making crank shafts - Google Patents

Description

April 30, 1957 Filed May 6, 1948 B. M. FINE PROCESS OF MAKING CRANK SHAFTS 3 Shets-Sheet 1 IN V EN TOR.

BERNARD F/NE BY ATLQRNEYS Ap 1957 B. M. FINE 2,790,227

PROCESS OF MAKING CRANK SHAF'TS Filed May 6. l948 INVENTOR. I BERNARD M. FINE AfTORNEYS 3 Sheets-Sheet 2 April 30, 1957 V B. M. FINE 2,790,227

PROCESS OF MAKING CRANK SHAFT-S Filed May 6, 1948 3 Sheets-Sheet 3 INVEN TOR.

BERNARD M. FINE BY ATTORNEYS United States Patent wow process or MAKING CRANK snnrrs' Bernard M. Fine, Philadelphia, Pa., assignor to Amelia S. Fine, Philadelphia, Pa.

Application May 6, 1948; set-tar No. 1 Claim. c1. 29-6) the finished crankshaft; and more particularly to provide a process wherein the unavoidable segregated elements and impurities of the steel will not be at or near any exposed surface of the crankshaft or so located as to render the crankshaft liable to rupture when in use.

Mechanism for practicing my improved process is illustrated in the accompanying drawings, ifi Whicli Fig. l is a perspective view of an ingot from which my improved-crankshaftmay be fabricated, (I

Fig. 2 discloses the ingot of Fig. l reshaped to give it a preferable cylindrical shape. e

Fig. 3 is a side view showing howthe piece of Fig.2 is further processed to produce a Work-piece con ipos ed of the elements that are subsequently reshaped t'o form the axial journals, c rankpins and webs of the finished crankshaft shown in Fig. 4. i

Fig. 4 is a perspective view of one embodiment of a finished crankshaft produced by ray process.

Fig 5 is a vertical sectional viewof'tli'e hyd 'r'atilid pfess adapted to effect reformation,- the View being in a direction radial of the work-piece shown therein.

Fig 6 is'a verticalsectional vi'ewofthe hydraiilidforg- {i I 'ing pr'e'ss taken-on the line 6 601 Fig. '5.

Fig. 7 is a plan view on the line 7-7 of Fig. 6.

Fig. 8 is a view similar to Fig. 6 showing the position of the parts at the end of the second crankshaft forming operation.

Fig. 9 is a side view of a section of the finished shaft showing the approximate path and form of the segregated metal and forging flow lines.

Illustrative of the objections to commercial methods of fabricating crankshafts may be cited one such method in common use. As in all processes, including that devised by me, there is first produced an ingot, such as shown in Fig. l, by pouring molten metal into a steel mold (casting) and subsequently cooling. The structure of the ingot is of a coarse, crystalline nature, the crystals forming a dendritic pattern. Cooling forces the impurities and segregated elements toward the center, producing a loose or porous center. While the zone included within the dotted longitudinal lines shown in Figs. 1 and 2 is not precisely indicative of this essentially weak central zone, the weakened irregular core, which is of more or less variable thickness, is included within, and may occupy a considerable part of, this zone. Refinement of the structure of this ingot by hot forging largely eliminates this coarse crystalline structure and dendritic preferably hydraulically operated, shown in'Fig. 3 placed therein.

pattern; but the ingot still retains a loose, porous center,- which isa source of weakness. It is common to forge suchan ingot. of a diameter large enough toenvelop the webs and cut out of the forging the crankshaft shown in Fig. 4; This method is expensive because of the excessive amount of steel required and the cost of removing the excessive steel. A still more serious objection is that the weak core of the finished crankshaft extends through the journal members and ends abruply at the webs, producing, particularly at the junction of webs and journal member, a condition very favorable to rupture.

Another commercial method of producing large cranks'ha fts is to forge the ingot to an approximately rectangular shape in cross-section modified further by forming rectangular pockets alternately on oppositesides of the ingot along its length and subsequently hot-twisting and reshaping the ingot; but this method is also wasteful of material and costly and the crank-shaft has the defects characteristic of the first described method.

While there have been proposed other methods of fabricating. crank-shafts that are less wasteful of material and less costly, they are less practicable as applied to large crank-shafts, do not eliminate the source of weakness above described and are not free of other objections. They have not therefore gone into general commercial use.v

My improved process is designed more particularly for the production of large crank-shafts, although it is applicable to the production of crank-shafts of any size. It utilizes-all thematerial of the work-piece solely by metal confinement and metal displacement simultaneously in different directions hereinafter described. The metal displacement is of such character as does not readily lend itself to drop forging, the displacement being effected by pressure and therefore most conveniently by a hydraulic press.

In Fig. 1 is'shown in perspective an ingot A which is conveniently of the shape shown in that figure and which may be subsequentlyforged to the shape shown in Fig. 2. The forging of Fig. 2 may be, by subsequent machining or forging, converted to the work-piece shown .in Fig. 3, whichcomprises an axial journal provided with collars c, spaced apart; the metal of which is subsequently displaced to form the journal sections a, web sections b and .pin sections 11 of the finished crank-shaft shown in Fig. 4.

In Figs. 5, 6 and 7 are shown the elements of a press, with the work-piece The elements of the press are shown in the position they occupy before the punch unit is operated to re-shape a section of the workpiece to crank-shaft configuration.

The upper face of the base e is provided with aligning concavities adapted to receive and support the journal members a between the first and second, and between the third and fourth, of the collars 0, these collars in Figs. 5 and 7 being conveniently numbered 1, 2, 3, 4, 5 and 6 respectively to facilitate clearness of future description. A cap 7, having aligning concavities complementary to those of the base, is bolted to the base, the base and the cap thereby cooperating to hold the workpiece in fixed position in the press and prevent any axial movement, during the operation of the press, of the collars.

Slidable in a vertically extending guideway g is an avil h which is engaged by the member between collars 2 and 3 and fills the space between them and thus cooperates with the supports for the work-piece previously described to prevent any axial movement of these two collars. The anvil h is held in supporting position by any suitable yieldable resistance, such as the spring 1' shown.

In the base e are guideways extending diametrically of the work-piece on opposite sides of collars 2 and 3. in

which guideways slidably extend web-shaping or forming blocks m, m, and which, at the start of the pressing operation, tangentially engage the peripheries of these collars. The outer faces of these blocks are inclined as shown at k.

The movable press platen of the die is provided with a displacing punch unit n aligning with the anvil h and provided with a concavity conforming to that of the anvil, and is also provided with wings having interior inclined or cam faces 2 corresponding to the inclined or cam faces k of the blocks m.

In operation the work-piece is heated to the proper forging temperature. The cap f is removed and after the workpiece is inserted into the die as hereinbefore described, the cap f is replaced to thereby hold the workpiece in the position shown in Figs. 5, 6 and 7.

In the descent of the press platen the punch unit 11 contacts with the member between collars 2 and 3 and at the same time the inclined faces p of the wings 0 contact with the inclined faces k of the blocks m. Further downward movement of the press platen displaces the metal of collars 2 and 3 and the connecting member so as to force such metal and anvil downward against the resistance of spring i to thereby reshape the collars 2 and 3 into webs w and the said connecting member into a pin d connecting the webs near their outer ends. At the same time blocks m are being forced laterally toward the axis of the work-piece to supply the metal needed to forge the webs to shape, that is, to reduce the width of the webs and reshape them to give them their approximately rectangular form with opposite flat cheeks, as shown in Fig. 4.

The successful operation of the process depends: first, upon so clamping the workpiece that the journal sections will not bend and so that the collars will be held from axial movement during the press-forging operation; second, upon the simultaneous displacement of the central member that is displaced to form the pin and the lateral diametric coacting inward pressures acting edgewise upon the collars. The direction of flow of the metal during this displacement operation is indicated by the dotted path -x shown in Figs. 8 and 9, which shows the location of the unavoidable weak core, such core extending through the axis of the journal members, along the longitudinal center of the webs and through the longitudinal center of the pins and being continuous. V

After the formation of a section of the complete shaf the press platen is raised, thus retracting the punch unit n and wings a. The web formers are moved outward and the cap 1' removed. The partially formed crank-shaft is then released from the press and turned through a prescribed angle and replaced on the press base with the web 3 and collars 4, 5 and 6 occupying the positions shown in Fig. 8. Actually, Fig. 8 shows the press elements in the position they occupy at the end of this second operation. The work-piece is then again manipulated and the press is then again operated as hereinbefore described to form another section of the crank-shaft.

The operations are then continued until the entire crank shaft is formed, the end collars then being removed, or being retained for use as coupling collars.

Crank-shafts formed by the described method are free from all weaknesses rendering them liable to rupture.

What I claim and desire to protect by Letters Patent The process of making a crank-shaft from a work-piece composed of a succession of collars connected together and spaced apart by journal members, the said collars and journal members having a common center forming the axis of the work-piece, said process comprising clamping the work-piece between the first and second, between the second and third, and between the third and fourth, of a succession of collars to hold the members between the first and second, and between the third and fourth, of said collars from radial displacement and to hold all said collars and the members between them from axial displacement, subjecting the journal member between the second and third collars and also the second and third collars to radial pressure in one direction and simultaneously applying coacting radial pressures at right angles to said direction to the peripheries of the second and third collars, the first named radial pressure displacing the metal of the journal member between the second and third collars outward from the axis of the work-piece to form web-connecting pins and at the same time displacing the metal of the second and third collars outward from the axis of the work-piece to elongate such collars into webs, and the second named radial pressure simultaneously compressing inward toward the axis the metal of the second and third web-forming collars to thus supply the metal required to allow their displacement and elongation in said first-named direction and their reshapement into oblong form without reduction in thickness; thereby simultaneously reshaping the last-named two collars and their connecting journal member to form webs and a connecting pin.

References Cited in the file of this patent UNITED STATES PATENTS 624,019 Harrington May 2, 1899 2,534,613 Meley Dec. 19, 1950 FOREIGN PATENTS 307,880 Germany Dec. 13, 19l7 779,043 France Mar. 28, 1935

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