US3735620A - Crankshaft rolling apparatus - Google Patents

Abstract

A crankshaft blank, having a cylindrical surface to be rolled and at opposite axial ends of which there are crankshaft fillets, is held between two lever arms under pressure. The lever arms are associated with a pair of master crankshafts in such a manner that, when the master crankshafts are rotated, the lever arms move correspondingly and in unison therewith. A tool unit is provided on one of the arms and includes a tool roller having axially arrayed portions of mutually opposite conicity, or two separate rollers which are conical in mutually opposite direction. The single roll or the two rollers engage the cylindrical surface of the blank intermediate the crankshaft fillets having at their respective axial end faces radii of curvature merging into their circumferential surfaces; these radii of curvature are smaller by between substantially 20-30 percent than the radius of the crankshaft fillets on the blank and thus also of the crankshaft fillets on the master crankshaft which are identical with the crankshaft fillets on the blank.

Description

United States Patent 1 1 1 397351629 Naumann 1 1 May 29, 1973 CRANKSHAF T ROLLING APPARATUS 1,070,955 12/1959 Germany ..29/6

lnventor: Hans-Joachim Naumann, Wassenberg, Germany Wilhelm Hegenscheidt Kommanditgesellschaft, Erkelenz, Germany Filed: Feb. 7, 1972 Appl. No.: 223,892

Assignee:

Foreign Application Priority Data References Cited UNITED STATES PATENTS GreatBritain ..72/l10 Primary ExaminerLowell A. Larson Attorney-Michael S. Striker [57] ABSTRACT A crankshaft blank, having a cylindrical surface to be rolled and at opposite axial ends of which there are crankshaft fillets, is held between two lever arms under pressure. The lever arms are associated with a pair of master crankshafts in such a manner that, when the master crankshafts are rotated, the lever arms move correspondingly and in unison therewith. A tool unit is provided on one of the arms and includes a tool roller having axially arrayed portions of mutually opposite conicity, or two separate rollers which are conical in mutually opposite direction. The single roll or the two rollers engage the cylindrical surface of the blank intermediate the crankshaft fillets having at their respective axial end faces radii of cutvature merging into their circumferential surfaces; these radii of curvature are smaller by between substantially 20-30 percent than the radius of the crankshaft fillets on the blank and thus also of the crankshaft fillets on the master crankshaft which are identical with the crankshaft fillets on the blank.

10 Claims, 6 Drawing Figures PATENILL M29 1915.

SHEET 1 [1r 4 PATENTEW- 3.735.620

SHEET 2 (1F 4 PAH-INTEL HAY 2 91973 SHEET 3 BF 4 WWW 1 CRANKSHAFT ROLLING APPARATUS BACKGROUND OF THE INVENTION The present invention relates to the rolling of a crankshaft and more particularly to a crankshaft rolling apparatus.

It is already well known to subject crankshafts to a rolling operation, in order to advantageously influence the material of the crankshaft and improve the fatigue loss thereof. This type of rolling apparatus. is known as a tangential fillet rolling apparatus and is employed for rolling the fillets on the. crankshaft, that is the curved transitions between crankpin and crankshaft bearing surfaces. Generally speaking, a known tangential fillet rolling, machine consists of a driving unit, two master crankshafts which drive lever arms but hold rolling tool: assemblies, a loading and an unloading device, and -such hydraulic cylindersand supply as are necessary to apply pressure to the tooling for the cold rolling operation of the crankshaft blank which is held between the lever arms. The latter are acted upon bythe hydraulic cylinders to put them through a moment of leverage and make it possible to apply a high squeeze pressure to the rolling tool assemblies which include actual rolling tools and back-up rollers. A crankshaft blank is loaded into the apparatus and thelever arms close the tooling aroundtthe blank, whereupon the driving mechanism for the master crankshafts causes the lever arms to reciprocate to thereby force the crankshaft blank. (the workpiece). to follow the same type of motion as it would when installed in an engine assembly. The rolling tool assemblies are applied against the surfaces on the crankshaft blank being worked, at a predetermined pressure to-thereby roll the surface. in uestion.

It is already known to utilize in the rolling toolassemblies'tool rollers of relatively small diameters which. are

supported by contact rollers of larger diameters, engag-- ing the latter at their circumference. The purpose of this arrangement is to be able to use tool rollers of small diameter in order to obtain high specific surface pressures upon the workpiece at relatively 'lowtool pressures or squeeze pressures. The tool rollers are used for rolling the fillets whereas the support rollers which support them are used to roll the circumferential surface intermediate the axially spaced fillets because this circumferential cylindricalsurface may become slightly bowed in radially outwarddirection as a result of the pressures exerted upon the fillets. The purpose of the support rollers is thus two-fold, namely on the one hand to support the tool rollers which act on the fillets and' on the other hand to attempt to either prevent or counteract (smooth out) this bowing effect of thecylindrical circumferential surface.

The tool rollers themselves are turnable about skew axes and the support rollers are so arranged with respect to the tool rollers that the latter tend to center and maintain the tool carrier assembly against movement in a sense which would permit contact of the tool rollers with the radial surfaces into which the respective fillets merge, that'is the surfaces which extend transversely of the longitudinal axes surrounded by the respective cylindrical surface. In some instances, and inparticular where crankshaft blanks (workpieces) of larger dimensions are to be so processed, it is possible to omit the tangential rolling of the fillets because the large dimension of the crankshaft provides sufficient material and fatigue life without rolling. However, with this type of crankshaft a bearing seat is required having the maximum possible supporting capability, a requirement which heretofore has been capable of achievement only by lapping. In view of the fact that a crankshaft in a four-cylinder engine having three main bearings already requires seven bearing surfaces which must be lapped, and that lapping during rotation of the crankshaft requires an additional axial swing movement at each bearing surface with the crankpins moving not about their axes, but in a circular orbit, it is clear that requirements for lapping the bearing seats on the crankpins are very expensive and complicated and that the lapping operation is time-consuming and accordingly expensive.

For this'reason it would be advisable to tangentially roll the main bearing surfaces and the surfaces on the crankpins, because this work will produce in the least possible time a surface havingthe least unevenness and having a high carrying capability. However, certain problems exist in any attempt to carry out this desirable operation, because the known tangential fillet rolling apparatuses do not provide for a reliable prevention of relative movements of the crankshaft blank (workpiece) and the tool rollers in axial direction of the crankshaft blank. Details of the type of prior-art machine which is utilized in the tangential rolling of crankshaft fillets may be found with reference to The tangential rolling of crankshaft fillets, General Motors Engineering Journal, Vol. 11, No. 3, 3rd Quarter, 1964. In the known prior-art apparatus which is described there and exemplary of what is known in the art, the crankshaft blank or workpiece is axially fixed against displacement by the inclined fillet rollers which are inclined in mutually opposite directions as seen with: respect to-the longitudinal axis of the crankshaft blank. This arrangement is quite satisfactory until, in accordance with-the above considerations suggesting that the. surfaces intermediate should also be rolled to avoid a separate lapping operation, an attempt is made toprovide a cylindrical roller in the same tool unit which utilizes the mutually inclined fillet rollers.

It was found that if this is attempted, there occurs a displacement. between the crankshaft blank and the tool unit in axial direction of the crankshaft blank, whichcauses portions of the tool unit or supports to move into engagement with the radial surfaces located at opposite axial ends of the cylindrical circumferential surfaces, that is the radial surfaces into which the fillets merge. It is believed that the reason for this difficulty resides in manufacturing tolerances because a very small inclination of the axis of the cylindrical roller (used in conjunction with the fillet rollers) with reference to the longitudinal axis of the crankshaft or the crankpins is sufficient to obtain the necessary thrust for causing such displacement. However, if such displacement does indeed'occur, the danger exists of substantial damage resulting, especially at the tool unit, because the amount by which such relative displacement can occur before contact results with the radial surfaces mentioned above, is very small.

Evidently, the purposes of the present invention cannot be achieved with the apparatus known from the prior art under the circumstances outlined above.

SUMMARY OF THE INVENTION It is, accordingly, a general object of the present invention to overcome the disadvantages set forth above with respect to the prior art.

More particularly it is an object of the present invention to provide a crankshaft rolling apparatus in which the aforementioned disadvantages of the prior art are avoided.

A further object of the invention is to provide such a crankshaft rolling apparatus in which the rollers can be utilized for rolling the circumferential cylindrical surfaces intermediate the fillets, but in which relative displacement between tool units and crankshaft blank (workpiece) in axial direction of the latter is reliably avoided.

The apparatus according to the present invention must be capable of afiording such rolling not only of the circumferential cylindrical surfaces on the crankpins but also on other portions of the crankshaft, that is the rolling also of the main bearing surfaces.

In pursuance of these and other objects which will still become evident, one feature of the invention resides in a crankshaft rolling apparatus having a pair of parallel master crankshafts journalled for rotation and having respective master portions each having a pair of detail. spaced fillets of predetermined radii of curvature and a circumferential bearing surface therebetween. A pair of connected lever arms extend transverse to the master crankshafts and are adapted to support between them under pressure an elongated crankshaft blank in parallelism with the master crankshafts and having an unfinished portion which also includes a pair of axially spaced fillets and an unfinished circumferential bearing surface therebetween. These arms are connected in motion-receiving relationship with the master crankshafts.

Drive means is provided for rotating the master crankshafts to thereby impart to the lever arms a reciprocatory motion in an arcuate path transverse to the elongation of the master crankshafts.

A first tool unit is provided on one of the arms and includes at least one rolling tool comprising a pair of conical portions of mutually opposite conicity, with these portions being adapted for rolling pressureengagement with the unfinished circumferential bearing surface of the unfinished portion of the crankshaft blank. According to the invention the conical portions of the rolling tool have axial end faces and circumferential surfaces, with the latter merging into the axial end faces on radii of curvature which are smaller than the aforementioned predetermined radii by between substantially to percent. A second tool unit is provided on the other arm and includes a counter roll adapted for engagement with the circumferential bearing surface of the unfinished portion of the blank, at the side opposite the rolling tool. Pressure exerting means urges the rolling tool and the counter roll towards one another.

The mutually opposite conicity of the conical portions provides for mutually opposite axial thrusts which cancel each other and prevent axial displacement between first tool unit and crankshaft blank. Thus, a small sliding displacement occurs between the conical portions and the crankshaft blank,.the displacement being the smaller the smaller the conicity which has been chosen. On the other hand, the conicity must be sufficient to afford such axially directed thrust as to counterbalance the thrust exerted by the other of the conical portions in the opposite direction, with both axial thrusts of course having to be sufficient to assure that no relative displacement between the conical portions and the crankshaft can occur, beyond the aforementioned small sliding movement. The latter is particularly advantageous in terms of the improved quality obtained thereby for the rolled surface, and the axial component of this small sliding movement combines with the axial thrust resulting from the conicity, with a torque being exerted upon the tool unit which can be absorbed by the journalling of the same.

The smaller radii of curvature at the opposite axial end faces of the conical portions assure that a contact of any portion of the tool unit with the earliermentioned radial surfaces-and resultant damage-is reliably avoided under all circumstances. All that can occur is that a respective end of a conical portion-the end having a smaller radius of curvature than that of the fillet which separates the cylindrical surface being rolled from the radial surface-will enter into one of the larger radius fillets; other displacement is then avoided by the radial force acting upon the rollers and maintaining the same in position in the respective tool unit so that the only consequence of such an incident will be the tangential rolling of the respective fillet, evidently not a disadvantage.

The conical portions need not be discrete, although they can be configurated as discrete rollers of mutually opposite conicity. However, they can also be provided on one and the same roller, as long as this roller is capable of producing symmetrical oppositely directed axial thrust forces, for instance a roller having a concavely recessed circumferential surface so that opposite axial end sections of the roller have mutually oppositely directed conicity. A roller of this configuration provides not only the desired advantages as well as the rolling of the circumferential cylindrical surface which it contacts, but is capable of giving the circumferential cylindrical surface a slightly outwardly convex contour of controlled configuration if this should be desired.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to the construction and method of operation thereof, together with additional objects and advantages, will best be understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a front-elevational view of an apparatus embodying the present invention, with the front cover of the apparatus removed to permit a view of the interior;

FIG. 2 is a section, on an enlarged scale, taken on line Il-II of FIG. 1;

FIG. 3 is a fragmentary section taken on line III'-III of FIG. 2;

FIG. 4 is a somewhat diagrammatic fragmentary sectional elevational detail view illustrating a detail of the invention;

FIG. 5 is a fragmentary elevation illustrating a further embodiment of the invention; and

FIG. 6-is a view similar to FIG. 5 but illustrating still another embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before discussing the drawing in detail it is pointed out that the apparatus as shown only incorporates the present invention, but is not inherently new. In other words, the invention has been illustrated in a basic tangential fillet rolling apparatus which is of the type for instance discussed in the earlier-mentioned General Motors publication.

With this in mind and referring now to the embodiment illustrated in FIGS. 1-4, it will be seen that in FIG. 1 there is shown a basic tangential fillet rolling apparatus in a front elevational view, with the front view wall removed to permit a view of the interior. The apparatus has a motor 4 which drives (refer also to FIG. 2) via belt or other suitable drives 2 and 3 respective master crankshafts 5 and 5. The master crankshafts are of exactly the same configuration as the crankshaft blank (workpiece) which is to be worked and which is identified with reference numeral ,6. Thus, the master crankshafts 5 and 5' have the main bearing surfaces 28, 26' and crankpins 5a and Sa', respectively. The master crankshafts 5 and 5' are journalled in one of two connected lever arms, 10, 13, namely in the lever arm as shown in FIG. 2, and when they are rotated by the motor 4, the master crankshafts 5 and 5' cause the lever arms 10 and 13 to perform a transverse or reciprocatory motion in an orbital path.

The arm 10 carries a tool unit 11 and the arm 13 carries a tool unit 7, and the crankshaft blank or workpiece 6 is located between the tool units 7 and 11, extending in axial parallelism with the master crankshafts 5 and 5' and being located in the same manner in which they are positioned, that is each bearing surface for a main bearing and each bearing surface of a crankpin of the workpiece 6 is associated with and journalled by one set of the tool units 7 and 11 (although only one set is illustrated because this is considered sufficient for an understanding of the invention). The master crankshafts 5 and 5' are driven in rotation in one and the same direction, being operatively associated for this purpose with gears 25, 26 and 27 which cooperate with one another for this purpose. This means that when the arms 10 and 13 move, the workpiece 6 will move in the same sense and if the tool units 7 and 11 are moved towards one another under pressure, they engage respective surface portions of the workpiece 6.

The apparatus described thus far is a conventional tangential fillet rolling apparatus in which the tools of the tool units 7 and 11 are of the type discussed earlier, that is provided with back-up or support rollers and with fillet-rolling rollers or tool rollers whose axes are mutually inclined with respect to the axial extension of the workpiece 6. Thus, in such an apparatus the workpiece 6 is maintained and guided only by the tool rollers, no other axial retention or centering device for the workpiece 6 being provided. Merely for the sake of completeness it is pointed out that if for instance the workpiece 6 is a crankshaft having seven bearing surfaces, that is three main bearing surfaces and the surfaces of a crankpins, the apparatus will have seven of the sets of arms 10 and 13 and seven of the sets of tool units 7 and 11, cooperating with the respective seven bearing surfaces.

Such conventional apparatus cannot, however, be used for rolling the bearing surfaces themselves, for the reasons outlined above; it can be utilized reliably and without danger of damage only for rolling fillets. If it is to be utilized for rolling the bearing surfaces themselves, it must be provided with the present invention for which purpose the tool units having the fillet rollers with their mutually inclined axes are removed and replaced with tool units 7 and 11 according to the present invention.

Reference should now be had to FIGS. 2-4 in partic' ular which show the invention in defail. The tool unit 7 is provided with a rolling tool in form of two discrete tool rollers or portions 8 and 9 which are located at opposite lateral sides of the axis of the workpiece 6 and which are of mutually opposite conicity (see FIG. 3). The rollers 8 and 9 contact the cylindrical surface which they are to treat on the workpiece 6, and are supported by the support ro back-up rollers 15 or 16 on the one hand and 17 and 18 on the other hand. The tool unit 11 is provided with a counter roller 12 which is supported against the surface of the workpiece 6 on the one hand and against the back-up rollers 19 and 20 on the other hand.

As the drawingshows, the tool unit 11 is connected to the arm 10, whereas the tool unit 7 is connected to the arm 13. The two arms are connected with one another by the pivot 14 and can be moved about this pivot with reference to one another by the hydraulic cylinder and piston unit 29 which requires no detailed description.

As more particularly shown in FIG. 3, the rollers 8 and 9 are of mutually opposite conicity, having identical cone angles and thus exerting upon the workpiece 6-whose surface they contact as also shown in FIG. 3- equal axial thrust, with the direction of thrust of the roller 8 being opposite to the direction of thrust exerted by the roller 9. Thus, the thrust forces exerted by the rollers 8 and 9 will cancel in each other and are in equilibrium.

As already pointed out before, a pair of arms 10, 13 and tool units 7 and 11 is provided to cooperate with each bearing surface (for instance seven or more) of the workpiece 6. Because the workpiece 6 is completely loose in so far as its retention against axial movement is concerned, it is necessary that the rollers of the tool units 7 and 11 not cause it to shift in axial direction. However, to prevent the possibility of damage in the event such movement should nevertheless occur, the present invention provides for the radius r of curvature at the opposite axial ends of the respective rollers 8 and 9 to be smaller by substantially 20 and 30 percent than the corresponding radius at the fillets of the master crankshaft, and thereby of the fillets on the workpiece 6 which are configurated in exact correspondence with those of the master crankshaft. FIG. 4 explains this most clearly. In FIG. 4 there is illustrated fragmentarily and in section a roller 8 having the circumferential surface 8a and the opposite axial end faces 8b. The radius r where the end faces 8b merge into the circumferential surface 8a should be compared with the fillet radius r+ 20-30 percent on which the cylindrical circumferential surface 51 of the portion of one of the master crankshafts 5 (the same is of course true also of the master crankshaft 5') merges into the two radial surfaces 52 located at opposite axial ends of the circumferential surfaces 51. The surfaces 51 and 52 correspond precisely to the similar surfaces provided on the workpiece 6, except that as mentioned before the radius r of the rollers 8 and 9 is smaller by 20-30 percent than the radius r 20-30 percent on the fillets of the master crankshafts 5 and 5'. It is evident that under these circumstances damage to the surfaces 52 is impossible even if the roller 8 should move as close as is possible in axial direction towards one of the surfaces 52, because all that will happen is that it will move into one of the fillets on the workpiece, corresponding to those shown on the master crankshaft in F IG. 4, and compact the material in the fillet without any portion of the roller 8 ever having a possibility of coming into contact and doing damage to the surfaces 52. The relationship of radius r on the rollers 8 and 9 with respect to the radius r 20-30 percent of the fillets has been found to be highly advantageous because it assures that no damage can occur to the surfaces 52.

In FIG. 5 l have illustrated an embodiment of the invention where only a portion of the workpiece 6 is shown, but wherein the conical contour of the rollers 8' and 9' is somewhat different from that of the rollers 8 and 9. In other respects this embodiment corresponds to the one discussed previously, and it should be noted that the radius 30 of the fillet on the workpiece 6 is larger (again by substantially 20-30 percent) than the radius 31 on the rollers 8' and 9, respectively.

The embodiment in FIG. 6, finally, again shows the workpiece 6. Here, however, the rolling tool which in the preceding embodiments was in form of tool rollers 8 and 9, or 8' and 9, respectively, is configurated as a single roller 21 having its circumferential surfaces concavely recessed as illustrated. Thus, the opposite axial portions of the roller 21 have mutually opposite conicity to achieve the oppositely directed symmetrical axial thrust forces. On the other hand, the opposite axial end faces of the roller 21 again merge into the circumferential surface thereof on radii which are smaller by substantially 2030 percent than the radii of the fillets on the workpiece 6, in keeping with the preceding embodiments. The roller 21 is engaged and urged against the surface of the workpiece 6 by a counter roller 22 of convex contour so as to matingly engage the concavity in the roller 21. If any unevennesses in the surface being treated by the roller 1 should result from the previous rolling of the fillets, then these would be smoothed out by the action of the roller 21 but the surface on the workpiece 6 would be given a slightly convex contour which may be desirable in some circumstances, because for instance it will aid in the axial guidance of the workpiece 6 in an engine assembly as well as preventing edge pressures in the bearing when the workpiece 6 is installed.

Thus, it will be seen that by a simple substitution of the rollers 8, 9 or 8, 9', or 21, according to the present invention (these rollers may of course already be installed in a complete tool unit with their cooperating counter or back-up rollers) in a tangential fillet rolling machine in place of the tool rollers which are used for rolling the fillets themselves, it has become possible to reliably, accurately and speedily roll the cylindrical bearing surface intermediate the respective fillets, utilizing the same tangential fillet rolling apparatus as before, and thus achieving significant economies not only in terms of operation but also in terms of investments, while further achieving a reliable protection against damage to the surface 52 and/or any portions of the respective tool units.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in a crankshaft rolling apparatus, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that from the standpoint of prior art fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is set forth in the appended 1. In a crankshaft rolling apparatus, in combination, a pair of parallel master crankshafts joumalled for rotation and having respective master portions each having a pair of axially spaced fillets of predetermined radii of curvature and a circumferential bearing surface therebetween; a pair of connected lever arms extending transverse to said master crankshafts and adapted to support between them under pressure an elongated crankshaft blank in parallelism with said master crankshafts and having an unfinished portion also including a pair of axially spaced fillets and an unfinished circumferential bearing surface therebetween, said arms being connected in motion-receiving relationship with said master crankshafts; drive means for rotating said master crankshafts and for thereby imparting to said lever arms a reciprocatory motion in an arcuate path transverse to the elongation of said master crankshafts; a first tool unit provided on one of said arms and including at least one rolling tool which comprises a pair of conical portions of mutually opposite conicity, said portions being adapted for rolling pressure-engagement with said unfinished circumferential bearing surface of said unfinished portion and having axial end faces and circumferential surfaces which merge into said axial end faces on radii of curvature which are smaller than said predetermined radii by between substantially 20-30 percent; a second tool unit on the other of said arms and including a counter roll adapted for engagement with said unfinished circumferential bearing surface of said unfinished portion at a side opposite said rolling tool; and pressure-exerting means for urging said rolling tool and said counter roll towards one another.

2. In an apparatus as defined in claim 1, wherein said conical portions of said rolling tool are discrete roller elements.

3. In an apparatus as defined in claim 2, wherein said roller elements have axes of rotation which extend in direction longitudinally of the crankshaft blank when the same is supported between said arms.

4. In an apparatus as defined in claim 1, wherein said rolling tool is a one-piece roller element, and wherein said conical portions are provided on the respective axial halves of said roller element.

5. In an apparatus as defined in claim 4, wherein said roller element has a circumferential surface surrounding an axis of rotation of said roller element and being concavely curved inwardly towards said axis intermediate the opposite axial ends of said roller element.

6. In an apparatus as defined in claim 5, wherein said first tool unit further comprises at least one back-up roller having a convexly curved circumferential surface and supportingly engaging said concavely curved surface of said roller element.

7. In an apparatus as defined in claim 1, said first tool unit further comprising back-up roller means in contact with and contoured for matingly engaging said conical portions.

8. In an apparatus as defined in claim 1, said crankshaft blank having a longitudinal axis; and wherein said conical portions are adapted to be located at opposite lateral sides of said longitudinal axis.

9. In an apparatus as defined in claim 1; further comprising connecting means connecting said arms for pivoting movement towards and away from one another; and force-exerting means for drawing said arms towards one another so as to exert pressure upon a crankshaft blank supported between them.

10. In a crankshaft rolling apparatus wherein an elongated workpiece having an unfinished portion provided with a pair of axially spaced fillets and an unfinished circumferential bearing surface therebetween is held under pressure between two arms which are caused to reciprocate in unison in an arcuate path transverse to the elongation of said workpiece by transmission of motion from two parallel rotating master crankshafts having respective master portions each having a pair of axially spaced fillets of predetermined radii of curvature and a respective master bearing surface therebetween, in combination, a first tool unit provided on one of said arms and including at least one rolling tool adapted for rolling pressure engagement with said unfinished bearing surface of said unfinished portion and comprising a pair of conical portions of mutually opposite conicity having axial end faces and circumferential surfaces which merge into said axial end faces on radii of curvature which are smaller than said predetermined radii by substantially 20-30 percent; and a second tool unit provided on the other of said arms and including a counter roller adapted for rolling pressure engagement with said unfinished bearing surface of said unfinished portion at a side thereof which is opposite said rolling tool.

Claims (10)

1. In a crankshaft rolling apparatus, in combination, a pair of parallel master crankshafts journalled for rotation and having respective master portions each having a pair of axially spaced fillets of predetermined radii of curvature and a circumferential bearing surface therebetween; a pair of connected lever arms extending transverse to said master crankshafts and adapted to support between them under pressure an elongated crankshaft blank in parallelism with said master crankshafts and having an unfinished portion also including a pair of axially spaced fillets and an unfinished circumferential bearing surface therebetween, said arms being connected in motion-receiving relationship with said master crankshafts; drive means for rotating said master crankshafts and for thereby imparting to said lever arms a reciprocatory motion in an arcuate path transverse to the elongation of said master crankshafts; a first tool unit provided on one of said arms and including at least one rolling toOl which comprises a pair of conical portions of mutually opposite conicity, said portions being adapted for rolling pressure-engagement with said unfinished circumferential bearing surface of said unfinished portion and having axial end faces and circumferential surfaces which merge into said axial end faces on radii of curvature which are smaller than said predetermined radii by between substantially 20-30 percent; a second tool unit on the other of said arms and including a counter roll adapted for engagement with said unfinished circumferential bearing surface of said unfinished portion at a side opposite said rolling tool; and pressure-exerting means for urging said rolling tool and said counter roll towards one another.

2. In an apparatus as defined in claim 1, wherein said conical portions of said rolling tool are discrete roller elements.

3. In an apparatus as defined in claim 2, wherein said roller elements have axes of rotation which extend in direction longitudinally of the crankshaft blank when the same is supported between said arms.

4. In an apparatus as defined in claim 1, wherein said rolling tool is a one-piece roller element, and wherein said conical portions are provided on the respective axial halves of said roller element.

5. In an apparatus as defined in claim 4, wherein said roller element has a circumferential surface surrounding an axis of rotation of said roller element and being concavely curved inwardly towards said axis intermediate the opposite axial ends of said roller element.

6. In an apparatus as defined in claim 5, wherein said first tool unit further comprises at least one back-up roller having a convexly curved circumferential surface and supportingly engaging said concavely curved surface of said roller element.

7. In an apparatus as defined in claim 1, said first tool unit further comprising back-up roller means in contact with and contoured for matingly engaging said conical portions.

8. In an apparatus as defined in claim 1, said crankshaft blank having a longitudinal axis; and wherein said conical portions are adapted to be located at opposite lateral sides of said longitudinal axis.

9. In an apparatus as defined in claim 1; further comprising connecting means connecting said arms for pivoting movement towards and away from one another; and force-exerting means for drawing said arms towards one another so as to exert pressure upon a crankshaft blank supported between them.

10. In a crankshaft rolling apparatus wherein an elongated workpiece having an unfinished portion provided with a pair of axially spaced fillets and an unfinished circumferential bearing surface therebetween is held under pressure between two arms which are caused to reciprocate in unison in an arcuate path transverse to the elongation of said workpiece by transmission of motion from two parallel rotating master crankshafts having respective master portions each having a pair of axially spaced fillets of predetermined radii of curvature and a respective master bearing surface therebetween, in combination, a first tool unit provided on one of said arms and including at least one rolling tool adapted for rolling pressure engagement with said unfinished bearing surface of said unfinished portion and comprising a pair of conical portions of mutually opposite conicity having axial end faces and circumferential surfaces which merge into said axial end faces on radii of curvature which are smaller than said predetermined radii by substantially 20-30 percent; and a second tool unit provided on the other of said arms and including a counter roller adapted for rolling pressure engagement with said unfinished bearing surface of said unfinished portion at a side thereof which is opposite said rolling tool.

Images