US2999298A - Apparatus for forging a crankshaft or similarly shaped part - Google Patents

Description

Sept. 12, 1961 P. DE FRAMOND APPARATUS FOR FORGING A CRANKSHAFT OR SIMILARLY SHAPED PART Filed June 25, 1959 4 Sheets-Sheet 1 INVENToR dc FRH HOMD Paul a QUM,W% 0 M Sept. 12, 1961 P. DE FRAMOND APPARATUS FOR FORGING A CRANKSHAFT 0R SIMILARLY SHAPED PART 4 Sheets-Sheet 2 Filed June 25, 1959 Sept. 12, 1961 P. DE FRAMOND 2,999,298

APPARATUS FOR FORGING A CRANKSHAF'I' OR SIMILARLY SHAPED PART Filed June 25, 1959 4 Sheets-Sheet 3 FIG. [0

L & I VENTOR Paul de FRAHOND Sept. 12, 1961 P. DE FRAMOND 99,298

APPARATUS FOR FORGING A CRANK-SHAFT OR SIMILARLY PART Filed June 25, 1959 4 Sheets-Sheet 4 INUE Paul Jfl FR/H Filed June 25, 1959, Ser. No. 822,8til Claims priority, application France Feb. 9, 1959 6 Claims. (Cl. 29-6) This invention relates to the forging of metallic parts of elongated shape including a plurality of axially spaced, radially offset sections in angularly displaced planes, separated by transverse web sections, such as crankshafts for multi-cylinder internal combustion engines and the like. Where the part being forged is a crankshaft, the said axially spaced, radially ofiset sections in angularly displaced planes constitute the respective crankpin sections of the crankshaft, while the transverse web sections separating the crankpin sections are the crankarms or webs of the crankshaft. Since the invention has especial utility in connection with the forging of crankshafts, the term crankpins and crankarms or webs will be broadly used in the present specification and claims for convenience in designating the respective sections of the elongated part being forged; it is to be expressly understood however that the use of such terms does not restrict the invention to apparatus for forging crankshafts.

More specifically my invention is concerned with that method of forging parts of the character described, wherein the initial forging blank comprises a plurality of coaxial, axially spaced crankpin blank sections corresponding in position to the crankpin sections in the final part, said crankpin blank sections being separated by intermediate enlargements corresponding in position to the crankarms of the final part, and said method involving applying transverse forging pressure to each of the crankpin blank sections in turn while simultaneously applying axial forging pressure components to both parts of the blank to either side from the particular crankpin section being forged, axially inwards towards said section being forged. Apparatus for forging crankshafts by such method has been disclosed for example in U.S. Patent 2,534,613 to Frangois Meley assigned to the assignee of the present application. As there described the advantages of such a method of forging crankshafts and similar parts include the features that the axial zone of the original ingot or blank coincides with the neutral fibre of the finished forging; that the portions of the part subjected to maximum strain correspond to the soundest parts of the original ingot or blank; and that the fibres of the metal are parallel to the outer surfaces of the part. These features are of course all conducive to the production of stronger and sounder forgings and a reduction in the number of defective forgings.

Apparatus for performing a forging operation by the method disclosed in that prior patent must generally include transversely displaceable forging means for exerting transverse forging pressure upon each one, in turn, of the crankpin blank sections that is being forged, and axially displaceable means for supporting said blank in a predetermined angular position (depending on the angular position of the particular crankpin being forged), and simultaneously exerting an axial forging pressure or thrust component thereon towards the crankpin being forged concurrently with the application of the aforementioned transverse forging pressure to the latter. Thus, said apparatus must include first axially displaceable cradling means to one side of said transverse forging means for cradling a crankpin blank section of said blank on one side from the crankpin being forged, and second axially displaceable cradling means to the other side of said transverse forging means for cradling a previously forged crankpin section on the other side from said crankpin being forged, means being of course provided for simultaneously forcing both said cradling means axially inwards towards the transverse forging means as the latter is being displaced transversely, in order to provide the desired composite forging action described.

It is found convenient in such apparatus to provide removable means for cradling the crankpin sections that have already been forged, i.e. in the so-called second cradling means mentioned in the foregoing paragraph. Such a removable cradle may conveniently comprise two separable sections adapted together to constitute a disk and formed with registering cutouts to define a cradling aperture for the forged crankpin to be cradled. These separable sections are arranged to be removably inserted in the respective lower and upper half swages of that one of the axially displaceable side forging means which receive the previously forged portions of the blank. However, in such known arrangements it will be easily understood that it is necessary to replace the removable cradle device whenever the angular displacement between the crankpin being forged and the precedingly forged crankpin, differs from the angular displacement between the last-mentioned crankpin and the crankpin that was forged immediately before it. Since such differences in angular displacement are a common occurrence in crankshafts, this situation creates an objectionable increase in the time and labor required for performing the forging operation, and it is the specific object of the present invention to overcome this situation and thereby expedite forging operations of the type described. Broader objects are to provide improved apparatus and devices for forging crankshafts and parts of similar character by the general method specified above.

The specific means provided by the invention whereby the above and further objects are accomplished will be clearly apparent from the ensuing description relating to an exemplary embodiment of the invention and modifications thereof, made with reference to the accompanying drawings, wherein:

FIG. 1 is a front view of a conventional type of removable cradle member as used in apparatus prior to this invention;

FIG. 2 is a partial sectional view of forging apparatus of the general type to which this invention relates;

FIG. 3 is a front view, on an enlarged scale, of a removable cradling device of improved construction in accordance with an embodiment of the present invention, with the plugging member omitted;

FIG. 4 is a side view corresponding to FIG. 3;

FIG. 5 is a front view of one form of a pivoted plugging member associated with the removable cradling device illustrated in FIGS. 3 and 4;

FIG. 6 is a side view of the plugging member shown in FIG. 5

FIG. 7 is a front view of the complete removable cradling device shown in FIGS. 3 and 4 with the plugging member of FIGS. 5 and 6 mounted therein, the device being illustrated in the condition where it is receiving a crankpin in one of the two cradling recesses thereof, said crank-pin shown in cross section;

FIG. 8 is a view similar to FIG. 7 but illustrating the device in the condition where it is supporting another crankpin being angularly displaced from that shown in FIG. 7;

FIG. 9 is a front view of a modified removable cradling device according to the invention, including means for latching the plugging member in one of its positions;

FIG. 10 is a partial view in axial cross section of the side supporting and forging means of the apparatus us ing improved cradling devices of the type shown in FIG. 9, to show the latching rod for latching the plugging member in one of its positions;

FIG. 11 is a front view of another modification of a cradling device according to the invention, provided with camming means for automatically positioning the plugging member to one of its selected positions, the device being shown with its two sections separated; and

FIG. 12 shows the same device as FIG. 11 after closure of the two sections thereof.

Referring particularly to FIG. 2, this shows a partial View of apparatus according to the invention for forging a crankshaft, which is generally similar in character to the apparatus shown in the aforementioned Patent 2,534,613. Thus, there are provided the lateral radling means or swages 4 and 3 which respectively receive the blank to be forged and the portion that has just been forged, and the central pair of half-swages 5 and 6 which act transversely to the length of the crankshaft for displacing each crankpin section of the blank as it is being forged in its turn. The upper swage portions are actuated by the pistons of an hydraulic press as shown, and it will be noted that whereas the central upper half swage 5 is ar,ranged to be forced vertically downwardly by its press piston, the side swages 3 and 4 are actuated by way of inclines or ramps such as 2t) whereby they exert an axial or longitudinal forging action on the blank simultaneously as the part of the blank gripped between the swages 5, 6 undergoes its transverse forging action. As the forging of each crankpin such as 2 is completed, the forged crankpin is positioned in a twopart supporting cradle 1 1 of the kind shown in front view in FIG. 1, and adapted to be supported in the swage 3, e.g. by means of recessesin the latter as shown.

The cradle is in two parts and includes an upper part 1 and a lower part 1 formed in the manner clearly apparent from FIG. 1 and each including a semi-circular cutout such that after assembly of the two cradle parts the two cutouts will constitute a circular aperture through which the crankpin 2 may be inserted to be supported therein in the proper position for forging the next crankpin of the crankshaft.

The arrangement so far described is conventional and is open to the following difiiculty. In any crankshaft each crankpin is angularly displaced from the foregoing crankpin by a certain angle and in most crankshafts this angular displacement is not the same as between consecutive pairs of adjacent crankpins. It will therefore be apparent that when the blank is shifted lengthwise from the position in which one crankpin has been forged to the position in which the next crankpin is to be forged, it will be necessary to remove the cradle from the precedingly forged crankpin and apply thereto a different cradle in order that the crankshaft will be supported in the proper angular position for forging the next crankpin, this requirement being a consequence of the unequal angular displacements between consecutive pairs of crankpins along the crankshaft as just noted.

In accordance with the present invention this difficulty is eliminated by the provision of an improved cradling means for supporting the crankpins, and specifically one in which there are provided more than one cradling recess for a crankpin, together with means for at least partly sealing the particular crankpin cradling recess that is not being used at a particular time. Usually two crankpin cradling recesses will be found sufficient for practical purposes.

Thus it will be understood that the last crankpin section that has been forged will be positioned in one or the other of the cradling recesses provided in the cradle, depending on the desired angular displacement between it and the next crankpin section to be forged, while the other cradling recess will be sealed. It should be noted in this connection that while the cradles have the primary function of determining the angular orientation of the crankshaft in each forging position, they simultaneously serve as thrust abutments for absorbing a large portion of the axial thrust component developed during each forging operation. Hence, unless the unused cradling recess in a cradle is sealed, the heated metal in the crankarm adjacent the cradle would tend to flow without meeting with any opposition at that location and would form an undesirable thickening in the crankann.

The means for plugging the unused cradling aperture may be shifted between the aperture either by displacement parallel to one face of the cradle, or by rotation about an axis normal to that face or rotation about an axis contained in the cradle and parallel to said face.

In the construction shown in FIG. 3, the cardle is formed with two apertures, for which purpose each of the two sections 10a, 10b of the two-part cradle is formed with two adjacent part-circular cutouts so that the parts of the cradle cooperate in defining the two merging circular apertures 11a and 11b. Each part 10a, 1011) of the cradle is further recessed internally all around said cutouts, as indicated in dotted lines in FIG. 3, so as to define the internal grooves or recesses 12a and 12b.

The shiftable plugging member is in the form of an arcuate sector 14 (see FIGS. 5 and 6) which has an apertured shank portion 17b of reduced thickness adapted to be pivotally mounted about a pin 13 disposed in the groove 12b within the lower cradle part 1% at a suitable position intermediate the cutouts therein; the sector member 14 further has a main body portion corresponding in thickness to that of the cradle, and an arcuate peripheral part 17a of reduced thickness adapted to ride in the grooves 12a and 12b of the upper and lower cradle parts.

As will be apparent from FIGS. 7 and 8, a crankpin 15a or 15b which has just been formed will be positioned, depending on its angular orientation, either in aperture 11a or in aperture 11b avhile the unused aperture 11/5 or aperture 11a, as the case may be, is plugged by the sector member 14. For this purpose thetwo parts of the cradle are separated and the sector member 14 is rotated to one or the other of its positions.

While in many cases, as in the embodiment described, the plugging member 14 will not tend to be displaced from the particular one of its end positions to which it has been moved, in other instances it may be desirable to provide means for latching it in one or in each position. Such an arrangement is shown in FIGS. 9 and 10. In the cradle of FIG. '9, the plugging member 14 is pivoted about a pin 16 and it will be noted that the pin is disposed near the upper periphery of the cradle rather than near the centre as in FIGS. 7 and 8. A latching rod 17 serves to latch the plugging member 14 in the upper one of its two positions by engagement through a notch provided therein. FIG. 10 shows the latch rod 17 extending through the forging jig assembly for actuation from one side of it.

Means may be provided in a cradle according to the invention for causing the plugging member to assume automatically its proper position on closure of the jig assembly under the action of suitable guide or camming means. Thus, in the embodiment shown in FIGS. 11 and 12, the improved cradle includes a small guide roller 18 rotatably mounted within the groove 12a in the upper cradle section 10a. When the plugging member 14 is in its upper or left-hand position shown in FIG. 11, and with the upper cradle section 10a raised as shown, the plugging member will be resting under gravity with its left side against a side of the lower cradle section 10b. This is because the arrangement is such that in the position just indicated the centre of gravity of the plugging member is arranged to lie to the left of the vertical plane passing through the pivotal centre 13 of the plug memher, As the upper portion of the jig assembly including the upper cradle section a is lowered down on to the lower portion, after the crankpin 150 has been inserted into the right-hand aperture of the lower cradle member, the roller 18 engages the top of the plug member 14 and constrains it to rotate clockwise about its axis 13, swingmg it to its correct position as shown in FIG. 12.

It will be understood that various constructional forms of the invention other than those illustrated and described may be conceivable by those skilled in the art within the scope of the ensuing claims, and that the invention is applicable to the forging, by the method described, of parts other than engine crankshafts.

What I claim is:

1. In apparatus for the forging of crankshaft-like elongated metal parts having a plurality of axially spaced, radially offset and angularly displaced crankpin sections separated by transverse webs, from an elongated blank having a plurality of crankpin blank sections corresponding in positions to said crankpins and separated by enlargements corresponding in position to said webs, said apparatus comprising transversely displaceable forging means for exerting transverse forging pressure upon each one in turn of said crankpin blank sections being forged and axially displaceable means for supporting said blank in a predetermined angular position and for exerting an axial forging pressure component thereon during the forging of each of the said crankpin sections, which axially displaceable means comprise a first means at one side of said forging means for cradling a crankpin blank section of said blank on one side from said crankpin being forged and a second means at the other side of said forging means for cradling a previously forged crankpin on the other side from said crankpin being forged, that improvement wherein said second cradling means has at least two angularly displaced and overlapping recesses, each of which is selectively operable to receive a crankpin cradlingly therein for supporting said blank in a predetermined angular position, and means for plugging the crankpin bounding portion of all of said recesses of said cradling means that do not receive a crankpin therein to prevent metal flow parallel to the crankpin axis.

2. In apparatus for forging elongated metal parts having a plurality of axially spaced, angularly displaced radially olfset crankpin sections separated by transverse webs, from an elongated blank having a plurality of axially spaced crankpin blank sections separated by enlargements, said apparatus comprising transversely displaceable forging means for exerting transverse forging pressure upon each one in turn of said crankpin blank sections being forged and axially displaceable means for supporting said blank in a selected angular position and exerting an axial forging pressure component thereon during the forging of each of the said crankpin sections, comprising a first means at one side of said forging means for cradling a crankpin blank section on one side from said crankpin being forged and a second means at the other side of said forging means for cradling a previously forged crankpin, that improvement wherein said second cradling means comprises a removable two-part cradle having at least two angularly displaced and overlapping recesses either of which is selectively capable of receiving a crankpin cradlingly therein for supporting said blank in said selected angular position, and means for plugging the crankpin bounding portions of all of said recesses of said cradling means that do not receive a crankpin therein to prevent metal flow parallel to the crankpin axis.

3. The improvement claimed in claim 2, wherein said two-part cradle comprise a pair of separable sections formed with registering cutouts to define said recesses in an assembled relative condition of said sections.

4. The improvement claimed in claim 2, wherein said two-part cradle comprise a pair of separable sections formed with registering cutouts to define said recesses in an assembled relative condition of said sections, and said means for plugging is pivotally mounted on one of said sections for displacement relatively thereto between positions in which said means for plugging is plugging respectively the appropriate portions of said recesses.

5. The improvement claimed in claim 4, including means provided for latching said plugging member in at least one of its said positions.

6. The improvement claimed in claim 4, including camming means provided on the other one of said sections for camming said means for plugging against the crankpin on relative movement of said sections towards said assembled relative condition.

References Cited in the file of this patent UNITED STATES PATENTS 2,535,295 La Font Dec. 26, 1950 2,747,253 Conchon I May 29, 1956 FOREIGN PATENTS 9,839 Great Britain 1906 1,015,665 Germany Sept. 12, 1957

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