METHOD AND DEVICE FOR THE IMPACT TREATMENT OF TRANSITION RADII OF A CRANKSHAFT

Abstract

The invention relates to a device for the impact treatment of transition radii (8) of a crank-shaft (4), in particular transition radii (8) between connecting rod bearing journals (5) and crank webs (7) and/or transition radii (8) between main bearing journals (6) and the crank webs (7) of the crankshaft (4). The device comprises an impact device (1) in order to introduce an impact force (FS) into at least one transition radius (8), wherein the impact device (1) has multiple impact heads (21) which are paired with the same transition radius (8).

Claims

1. An apparatus for the impact-hardening of transition radii of a crankshaft, in particular of transition radii between connecting-rod bearing journals and crank webs and/or transition radii between main bearing journals and the crank webs of the crankshaft, comprising at least one impact device for introducing an impact force into at least one transition radius, wherein the impact device has multiple impact heads which are assigned to the same transition radius, wherein the impact device has multiple impact tools with multiple impact heads, wherein the impact heads of at least two impact tools are assigned to the same transition radius.

2. (canceled)

3. (canceled)

4. The apparatus as claimed in claim 1, wherein the impact device has an impact piston and a deflecting unit, wherein the at least one impact tool is arranged at the deflecting unit, and wherein the impact piston transmits an impulse to the at least one impact tool via the deflecting unit, and the one or more impact heads of the at least one impact tool introduce(s) the impact force into the associated transition radius.

5. The apparatus as claimed in claim 1, wherein the impact heads are arranged offset one behind the other during the impact hardening of a transition radius running in annularly encircling fashion around the connecting-rod bearing journal.

6. The apparatus as claimed in claim 1, wherein at least two impact heads assigned to the same transition radius, are arranged such that the impact heads each generate their own tracks of impact impressions during the impact hardening of a transition radius running in annularly encircling fashion around the connecting-rod bearing journal.

7. The apparatus as claimed in claim 6, wherein the tracks of the impact impressions overlap.

8. The apparatus as claimed in claim 1, wherein at least two impact heads assigned to the same transition radius, are arranged such that the impact heads generate tracks, situated in each case one inside the other, of impact impressions during the impact hardening of a transition radius running in annularly encircling fashion around the connecting-rod bearing journal.

9. The apparatus as claimed in claim 1, that the impact heads for the impact hardening have a spherical surface.

10. The apparatus as claimed in claim 1, wherein the impact heads have different sizes.

11. The apparatus as claimed in claim 4, wherein the apparatus is configured to adjust the spacing between a deflection point of the deflecting unit and the front end of the one impact head of the at least one impact tool.

12. A method for the impact hardening of transition radii of a crankshaft, in particular of transition radii between connecting-rod bearing journals and crank webs and/or transition radii between main bearing journals and the crank webs of the crankshaft by means of an apparatus as claimed in claim 1.

13. A crankshaft produced in accordance with a method as claimed in claim 12.

14. The apparatus as claimed in claim 1, wherein the impact heads are arranged offset adjacent to one another during the impact hardening of a transition radius running in annularly encircling fashion around the connecting-rod bearing journal.

15. The apparatus as claimed in claim 1, wherein the impact heads are arranged offset one behind the other during the impact hardening of a transition radius running in annularly encircling fashion around the main bearing journal.

16. The apparatus as claimed in claim 1, wherein the impact heads are arranged offset adjacent to one another during the impact hardening of a transition radius running in annularly encircling fashion around the main bearing journal.

17. The apparatus as claimed in claim 1, wherein the impact heads are arranged offset one behind the other and offset adjacent to one another during the impact hardening of a transition radius running in annularly encircling fashion around the main bearing journal.

18. The apparatus as claimed in claim 1, wherein the impact heads are arranged offset one behind the other and offset adjacent to one another during the impact hardening of a transition radius running in annularly encircling fashion around the connecting-rod bearing journal.

19. The apparatus as claimed in claim 1, wherein the impact heads are arranged offset one behind the other and offset adjacent to one another during the impact hardening of a transition radius running in annularly encircling fashion around the connecting-rod bearing journal and the main bearing journal.

20. The apparatus as claimed in claim 1, wherein at least two impact heads assigned to the same transition radius, are arranged such that the impact heads each generate their own tracks of impact impressions during the impact hardening of a transition radius running in annularly encircling fashion around the main bearing journal.

21. The apparatus as claimed in claim 1, wherein at least two impact heads assigned to the same transition radius, are arranged such that the impact heads generate tracks, situated in each case one inside the other, of impact impressions during the impact hardening of a transition radius running in annularly encircling fashion around the main bearing journal.

22. The apparatus as claimed in claim 4, wherein the apparatus is configured to adjust the spacing between a deflection point of the deflecting unit and the front end of the multiple impact heads of the at least one impact tool.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0117] Exemplary embodiments of the invention will be described in more detail below on the basis of the drawing.

[0118] The figures each show preferred exemplary embodiments, in which individual features of the present invention are illustrated in combination with one another. Features of an exemplary embodiment are also implementable separately from the other features of the same exemplary embodiment, and may accordingly be readily combined by a person skilled in the art with features of other exemplary embodiments in order to form further meaningful combinations and sub-combinations.

[0119] In the figures, functionally identical elements are denoted by the same reference designations.

[0120] In the figures, in each case schematically: FIG. 1 shows an overall view of an apparatus according to the invention for carrying out the method in a first embodiment;

[0121] FIG. 2 shows a perspective view of a part of the apparatus according to the invention for carrying out the method in a second embodiment;

[0122] FIG. 3 shows an impact device with two impact tools in an enlarged illustration as per the detail “A” from FIG. 1;

[0123] FIG. 4 shows an impact device with only one impact tool;

[0124] FIG. 5a is an enlarged illustration of a transition radius and of an impact tool with three impact heads;

[0125] FIG. 5b is an enlarged illustration of a transition radius and three flattened impact tools with in each case one impact head;

[0126] FIG. 6 shows an example of an offset of impact heads;

[0127] FIG. 7 shows a transition radius impact-hardened by means of three impact heads, with three overlapping tracks of impact impressions;

[0128] FIG. 8 shows a transition radius impact-hardened by means of two impact heads, with tracks of impact impressions situated one inside the other;

[0129] FIG. 9 shows an impact device with two telescopic impact tools;

[0130] FIG. 10 is an enlarged illustration of a transition radius and of an impact tool with an impact head, wherein the impact tool is aligned at a first impact angle;

[0131] FIG. 11 is an enlarged illustration of a transition radius and of an impact tool with an impact head, wherein the impact tool is aligned at a second impact angle;

[0132] FIG. 12 shows an impact-hardened transition radius in the case of which a first impact angle has been used for the impact hardening;

[0133] FIG. 13 shows an impact-hardened transition radius in the case of which a second impact angle has been used for the impact hardening; and

[0134] FIG. 14 shows an impact-hardened transition radius in the case of which the impact angle has been varied during the impact hardening along the transition radius running in annularly encircling fashion around the journal.

DETAILED DESCRIPTION OF THE INVENTION

[0135] The apparatus illustrated in an overall view in FIG. 1 basically corresponds in terms of its construction to the apparatuses as per DE 34 38 742 C2 and EP 1 716 260 B1 with one or more impact devices 1, for which reason only the important parts, and the differences in relation to the prior art, will be discussed in more detail below.

[0136] The apparatus has a machine bed 2 and a drive device 3. The drive device 3 is used to move or rotate a crankshaft 4 along a direction of rotation into an impact position. The crankshaft 4 has connecting-rod bearing journals 5 and main bearing journals 6, between which crank webs 7 are arranged in each case. Transition radii 8 (see FIGS. 3 to 8 and 10 to 14) are formed between connecting-rod bearing journals 5 and crank webs 7 and between main bearing journals 6 and crank webs 7, or generally between transitions in cross section of the crankshaft 4.

[0137] At that side of the crankshaft 4 which faces toward the drive device 3, there is provided a fastening device 9 which has a clamping disk or a fastening flange 10. On that side of the crankshaft 4 which is averted from the drive device 3, a support 11 preferably in the manner of a tail-stock is provided, which has a further fastening device 9 for the purposes of rotatably receiving or rotatably fixing the crankshaft 4. Optionally or in addition to the support 11, a back rest may be provided which is positioned at a rotationally symmetrical location.

[0138] The drive device 3 is capable of setting the crankshaft 4 in rotation motion along an axis of rotation C. Provision may be made here whereby the main axis of rotation C.sub.KW of the crankshaft 4 is positioned eccentrically from the axis of rotation C of the drive device 3, as illustrated in FIG. 1 and FIG. 2. For this purpose, it is preferably possible for alignment means 17 (see FIG. 2) to be provided in the region of the fastening device 9. Here, provision may be made whereby the alignment means 17 displace a central axis of the journal 5, 6 that is respectively to be hardened such that the central axis of the journal 5, 6 lies on the axis of rotation C.

[0139] A direct drive, preferably without a clutch, may be provided for the drive device 3. A motor, preferably an electric motor, of the drive device 3 can thus be coupled without a transmission ratio or transmission to the fastening device 9 or to the crankshaft 4. An input shaft 13 or a drive shaft may be provided for transmitting the drive power.

[0140] The impact devices 1 described in more detail by way of example below are each held adjustably in a displacement and adjustment device 15 in order to adapt them to the position of the connecting-rod bearing journals 5 and of the main bearing journals 6 and to the length of the crankshaft 4.

[0141] The support 11 may also be designed to be displaceable, as indicated by the double arrows in FIG. 1.

[0142] Two impact devices 1 are illustrated in FIG. 1, though basically any number of impact devices 1 may be provided, for example also only a single impact device 1.

[0143] For the operation of the drive device 3, which preferably comprises an electric motor, closed-loop position control may be used in order to rotate the crankshaft 4 into the respective impact position, wherein the crankshaft 4 is rotated preferably in stepped or clocked fashion.

[0144] After a transition radius 8 has been impact-hardened in the desired manner, the impact device(s) 1 can be moved to the next transition radii 8 that are to be hardened.

[0145] FIG. 2 illustrates, in a perspective view, a detail of a further apparatus for carrying out the method according to the invention but without an impact device. Here, the apparatus of FIG. 2 is substantially identical to the apparatus of FIG. 1, for which reason only the important differences will be referred to in detail below.

[0146] A drive device 3 is once again provided. Furthermore, a fastening device 9 is provided which has a fastening flange 10 and, fastened thereto, a face plate with clamping jaws for fixing the crankshaft 4. The face plate with the clamping jaws of the fastening device 9 is arranged on the fastening flange 10 adjustably on an alignment means 17, whereby the longitudinal axis C.sub.KW of the crankshaft 4 can be displaced relative to the axis of rotation C of a drive shaft or of an input shaft 13.

[0147] The crankshaft 4 of FIG. 2 has a configuration which deviates from the embodiment illustrated in FIG. 1, but basically likewise comprises connecting-rod bearing journals 5, main bearing journals 6 and crank webs 7.

[0148] In FIG. 2 (as in FIG. 1), a further fastening device 9 may be provided at that end of the crankshaft 4 which is averted from the drive device 3, though said further fastening device may also be omitted.

[0149] An impact device 1 of FIG. 1 is illustrated in more detail by way of example in FIG. 3. The invention may basically be implemented with any impact device 1. The impact device 1 described below is however particularly suitable. It has a main body 18 which may be provided with a prismatic abutment correspondingly to the radius of the crankshaft segment to be machined, and which preferably has guides 19 which guide two impact tools 16 in their support plane and provide them with a corresponding degree of freedom in terms of the support angle or impact angle α (see FIGS. 9 to 11) about a deflecting unit 20, which is advantageous for the adaptation to the dimensional conditions of the crankshaft 4. In each case one ball as impact head 21 is arranged at the front ends of the two impact tools 16. An intermediate part 22 produces the connection between an impact piston 23 and the deflecting unit 20, which transmits the impact energy to the impact tools 16. The intermediate part 22 may possibly also be omitted.

[0150] According to the invention, provision is made whereby the impact device 1 has multiple impact heads 21 which are assigned to the same transition radius 8.

[0151] For this purpose, provision may be made whereby the impact device 1 has at least one impact tool 16 with multiple impact heads 21. In the sectional illustration of FIG. 3, in each case only one impact head 21 is illustrated in the drawing for the respective transition radius 8 owing to the illustration. Nevertheless, in the variant of FIG. 3, it is possible for multiple impact heads 21, which are for example offset one behind the other, to be arranged for one or for both transition radii 8. In particular, in the case of the impact device 1 of FIG. 3 with the two impact tools 16, it is thus also possible for only one of the two impact tools 16 to have multiple impact heads 21 which are assigned to the same transition radius 8.

[0152] In the context of the invention, provision may also be made whereby the impact device 1 has multiple impact tools 16, wherein at least two impact tools 16 each have one or more impact heads 21 which are assigned to the same transition radius 8. Here, the impact tools 16 assigned to one transition radius 8 may each have one or more impact heads 21.

[0153] The impact device 1 of FIG. 3 may also be an impact device in the case of which in each case only one impact head 21 is provided for the impact tools 16 if, for example, a second impact device 1 is provided (see for example in FIG. 1) which has multiple impact heads 21 which are assigned to the same transition radius 8.

[0154] It is also possible for multiple impact devices 1 to be provided, wherein at least two impact heads 21 of the impact devices 1 are assigned to the same transition radius 8.

[0155] To increase the effectiveness of the impact, a clamping prism 24 may be fastened, via springs 25, by means of adjustable clamping bolts 26 with clamping nuts 27 to that side of the journal 5, 6 which is averted from the main body 18. Other structural solutions are also possible here.

[0156] By means of the arrangement of multiple impact devices 1 over the length of the crankshaft 4 to be machined, it is possible, as required, for all centrally and possibly eccentrically running regions of the crankshaft 4 to be machined simultaneously. As already mentioned, in this case, it is not necessary for all of the impact devices 1 to have multiple impact heads 21 assigned in accordance with the invention.

[0157] The impact piston 23 transmits an impulse to the impact tools 16 via the deflecting unit 20, whereby the impact heads 21 of the impact tools 16 introduce the impact force F.sub.S into the transition radii 8.

[0158] The expression “F.sub.S” and similar expressions in the present description are to be understood merely as placeholders/variables for any impact force that appears appropriate to a person skilled in the art. Here, where the description refers to “the impact force F.sub.S”, this may thus refer in each case to different or else identical impact forces.

[0159] FIG. 4 shows an impact device 1 which is equipped with only one impact tool 16. In the exemplary embodiment shown, the impact device 1 is preferably inclined relative to the crankshaft 4, specifically such that the impact tool 16, the longitudinal axis L.sub.s of which is arranged coaxially with respect to the longitudinal axis of the impact device 1, impacts perpendicularly against the region of the crankshaft segment to be machined, in the present case of the transition radius 8 to be machined. In this case, although it is possible for in each case only one crankshaft segment to be machined, the structural design and the transmission of force by the impact device 1 are on the other hand better and simpler. Bore ends can additionally be hardened by means of this impact tool 16 in a standing position.

[0160] This embodiment has proven particularly advantageous for use on non-symmetrical crankshaft segments, such as the end regions and the oil bore ends of the crankshaft 4.

[0161] As in FIG. 3 already, it is also the case that only one impact head 21 is illustrated in the drawing in the case of the impact device 1 of FIG. 4. The impact device 1 of FIG. 4 may however have any number of impact heads, for example two impact heads, three impact heads or four impact heads. Furthermore, multiple impact devices 1 and/or impact heads 16 of the type illustrated in FIG. 4 may be provided which have in each case one or more impact heads 21 and which are assigned to the same transition radius 8.

[0162] FIG. 5a illustrates, in highly schematic form, an impact tool 16 with three impact heads 21, wherein the impact heads 21 are assigned to the same transition radius 8. An even further enlarged and even more highly schematic illustration of the geometrical relationships in this regard is shown (in greatly exaggerated form) in FIG. 6.

[0163] Here, FIGS. 5a and 6 show an arrangement of three impact heads 21 which, during the impact hardening of the transition radius 8 running in annularly encircling fashion around the exemplary crankshaft segment, are arranged offset one behind the other and adjacent to one another. In this way, internal compressive stresses can be introduced along the circumference of the transition radius 8 over a wide range or a large “width” b and with a simultaneously high depth effect (indicated in FIG. 5a by the hatched region MAX).

[0164] Here, the impact heads 21 are arranged such that, during the impact hardening of the transition radius 8 running in annularly encircling fashion around the illustrated crankshaft segment, the impact heads 21 each generate their own tracks of impact impressions 28 (see FIG. 7).

[0165] The impact heads 21 may be arranged offset one behind the other and/or offset adjacent to one another such that the tracks of the impact impressions 28 overlap.

[0166] As already indicated above, the impact heads 21 for the impact hardening may have a spherical surface or may be of substantially spherical form.

[0167] If provision is made whereby the tracks of impact impressions 28 of the impact heads 21 overlap, an arrangement illustrated in exaggerated form in FIG. 6 is advantageous. Here, the impact heads 21 are arranged offset with respect to one another such that an overlap of the geometry of the impact heads 21 in a circumferential direction of the transition radius 8 is, as viewed in cross section, situated within the crankshaft 4. In the example of FIG. 6 with the impact heads 21 with the spherical surface, the intersection points S of the respective circle circumferences is arranged within the transition radius 8, that is to say within the crankshaft 4. Here, the penetration depth t (illustrated in exaggerated form) of the impact heads 21 during the impact hardening must be taken into consideration.

[0168] As already mentioned above, provision may also be made of multiple impact tools 16 with in each case one or more impact heads 21 which are assigned to the same transition radius 8. To further illustrate this, an exemplary variant of the invention is illustrated in FIG. 5b. In the variant of FIG. 5b, three impact tools 16 are provided which have in each case one impact head 21. Thus, similarly to the embodiment shown in FIG. 5a, it is once again the case that three impact heads 21 are provided which are assigned to the same transition radius 8.

[0169] The impact tools 16 introduce the impact force Fs along their respective longitudinal axis L.sub.S into the transition radius 8. Here, the impact tools 16 are arranged on the deflecting unit 20 (in order to simplify the illustration, only the deflection point U.sub.P of the deflecting unit is illustrated in FIG. 5b). The impact tools 16 may be designed, and oriented relative to one another, such that the impact tools support one another during the introduction of the impact force F.sub.S, such that said impact tools do not slip out of their associated respective impact position along the circumference of the transition radius 8. Alternatively and/or in addition, the position of the deflecting point U.sub.P may deviate from the position shown and be arranged for example closer to the transition radius 8, resulting in a changed impact angle α for the outer impact tools 16, which can likewise prevent slippage.

[0170] The illustration of FIG. 5b is in any case to be understood as being merely schematic, in particular with regard to the proportions and angle orientations.

[0171] The impact tools 16 are arranged one above the other and/or so as to overlap, and, for this purpose, may be of particularly flat form in order to allow for the relatively constricted geometrical requirements. In the variant shown in FIG. 5b, an impact tool 16 arranged centrally along the circumference of the transition radius 8 is offset behind the two other impact tools 16, whereby an even more constricted arrangement of the impact tools 16 and thus of the impact heads 21 can be achieved. It is however basically possible for any offset of the impact tools 16 with respect to one another to be provided.

[0172] FIG. 7 illustrates an exemplary transition radius 8 between a main bearing journal 6 and a crank web 7, in the case of which the impact impressions 28 that have been generated by respective impact heads 21 overlap along the transition radius 8 running in annularly encircling fashion around the main bearing journal 6. Here, during a subsequent impact, the respective impact head 21 penetrates at least partially into the impact impression 28 of the preceding impact, giving rise to the “track” of impact impressions 28 illustrated in FIG. 7 and in the following figures. The characteristic hardening pattern or the overlapping tracks of the impact impressions 28 may be achieved for example by means of an arrangement with impact heads 21 offset one behind the other and adjacent to one another, as illustrated in FIG. 5a or 5b. The internal compressive stresses are thus introduced into the crankshaft 4 over a large width b along the circumference of the transition radius 8.

[0173] FIG. 8 illustrates a further exemplary transition radius 8 which exhibits two tracks, situated one inside the other, of impact impressions 28. Such a pattern may be achieved for example by virtue of two impact heads 21 being arranged one behind the other such that, during the impact hardening of a transition radius 8 running in annularly encircling fashion around the main bearing journal 6, the impact heads 21 each generate impact impressions 28. Here, the impact head 21 that generates the inner track of impact impressions 28 is smaller than the impact head 21 that generates the outer track of impact impressions 28.

[0174] Provision may thus be made for the impact heads 21 to have different sizes. The impact heads 21 may also be of the same size. Provision may also be made for the second impact head 21, that is to say the impact head 21 that impacts in the impact impression 28 that has already been generated by the first impact head 21, to be larger.

[0175] By means of impact hardening in the manner of FIG. 8, it is for example possible for internal compressive stresses to be introduced into the crankshaft 4 to a hitherto unattained depth.

[0176] In one particular variant of the invention, provision may be made whereby the spacing d (cf. FIG. 9) between a deflection point Up of the deflecting unit 20 and the front end of the respective impact head 21 or of the respective impact heads 21 of the impact tools 16 being adjustable.

[0177] One possible technical solution for the adjustment of the spacing d is illustrated in schematic form by dashed lines in FIG. 3, in which a changeover device 30 with a magazine is provided in order to exchange the at least one impact tool 16 and/or the at least one impact head 21 and/or the deflecting unit 20 and/or the at least one impact device 1 in order to adjust the spacing d between the deflection point U.sub.P of the deflecting unit 20 and the front end of one or multiple impact heads 21 of the at least one impact tool 16 to a different value. In particular, a changeover device 30 for the exchange of impact tools 16 is indicated in FIG. 3. For this purpose, the changeover device 30 comprises a selection of impact tools 16 of in each case different length. By exchanging an impact tool 16, the spacing d and thus the impact angle α can therefore be adjusted.

[0178] Provision may also be made whereby the length of the impact tools 16 is adjustable, preferably telescopically. A corresponding construction is illustrated in FIG. 9. Here, FIG. 9 shows a detail of an impact device 1, which may be of substantially identical design to the embodiment of FIG. 3.

[0179] In FIG. 9, two telescopic impact tools 16 are schematically illustrated. By means of the adjustable length of the impact tools 16, the spacing d between the deflection point U.sub.P of the deflecting unit 20 and the front end of an impact head 21 is adjustable. In this way, it is thus indirectly also possible for the impact angle α and possibly also the impact position to be influenced.

[0180] Provision may also be made, as illustrated in FIG. 1, for multiple impact devices 1 to be used. The respective spacing d between the deflection point Up and the impact heads 21 is then preferably not identical at least in the case of two impact devices 1. This makes it possible for the impact devices 1 to be used in each case for the impact hardening of a transition radius 8 or of a group of transition radii 8, wherein the impact tools 16 of the impact device 1 are in each case already adjusted to the preferentially provided impact angle α. Conversion of the impact device 1 is thus not necessary. If the crankshaft 4 has only transition radii 8 with two different advantageous impact angles α, it is thus preferably the case that two correspondingly preset impact devices 1 are sufficient.

[0181] Provision may for example be made whereby a first impact device 1 introduces impact forces F.sub.S at a first impact angle α.sub.1 and a second impact device 1 introduces impact forces F.sub.S at a second impact angle α.sub.2. Use may also be made of impact devices 1 in the case of which the spacing d and/or the impact angle α is adjustable in a different way. It is also possible for a conventional impact device to be combined with an impact device 1 with adjustable spacing. Any combinations, also with an impact device 1 with multiple impact heads 21 which are assigned to the same transition radius 8, are conceivable within the scope of the invention.

[0182] Provision may be made whereby the impact angle α between the longitudinal axis L.sub.S of the at least one impact tool 16 and a line l.sub.KW perpendicular to the longitudinal axis C.sub.KW of the crankshaft 4 amounts to 5° to 80°, preferably 10° to 70°, more preferably 20° to 60° and particularly preferably 30° to 55°, in particular 35° to 50°.

[0183] To illustrate the relationships, FIGS. 10 and 11 illustrate enlarged views which highly schematically illustrate an impact head 21 of an impact tool 16 and an exemplary transition radius 8 of a crankshaft 4. All relationships self-evidently also apply if multiple impact heads 21 are provided. Here, in the example of FIG. 10, impact hardening is performed at a first impact angle α.sub.1, and in FIG. 11, impact hardening is performed at a second impact angle α.sub.2.

[0184] Through the corresponding adjustment of the impact angle α by means of the variation of the spacing d between the deflection point Up of the deflecting unit 20 and the at least one impact head 21 of the impact tool 16, the direction of the impact force F.sub.S can be predefined, whereby the range of greatest effectiveness of the impact hardening can be set in targeted fashion.

[0185] Provision may also be made for the impact force F.sub.S to be reduced in targeted fashion or for the direction of action to be varied, for example if reduced cross sections, bores or other geometrical conditions necessitate this.

[0186] Preferably, the impact angle α is selected in accordance with the profile of a loading maximum MAX.sub.1, MAX.sub.2 of the transition radius 8, wherein the profile of the loading maximum MAX.sub.1, MAX.sub.2 is determined on the basis of simulations and/or calculations and/or series of tests of the respective crankshaft type.

[0187] In FIG. 11, the impact head 21 is positioned at the same position of the transition radius 8 as in FIG. 10. However, the spacing d between the deflection point Up of the deflecting unit 20 and the impact head 21 is set such that the impact tool 16 is aligned at a different impact angle α than in FIG. 10. It follows from this that the impact is introduced into the transition radius 8 at the angle α.sub.2, even though the impact head 21 is basically applied at the same position as in FIG. 10.

[0188] The illustration in FIG. 11 differs to a particularly great extent from the illustration in FIG. 10 for illustrative purposes.

[0189] It is basically also possible for the positioning of the impact head 21 in the transition radius 8 to be varied, that is to say the impact head 21 could possibly also be applied at a different position along the circumference of the transition radius 8, wherein, at the same time, the impact angle α may be variable.

[0190] As already mentioned, the impact head 21 or the impact heads 21 can have different sizes. In particular, if only one impact head 21 is provided on an impact tool 16, the impact head 21 may have a radius rs of which the magnitude amounts to 75% to 99% of the transition radius 8, preferably 85% to 98% of the transition radius 8 and particularly preferably 85% to 95% of the transition radius 8. The radius r.sub.S of the impact head 21 preferably substantially corresponds to the transition radius 8.

[0191] The impact heads 21 may basically be of any size. If multiple impact heads 21 are provided on an impact tool 16, the impact heads 21 may for example be larger than 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or 90% of the transition radius 8. The size of an impact head 21 may however also be smaller than 10% of the size of the transition radius 8 or correspond to the size of the transition radius 8.

[0192] FIGS. 12 and 13 illustrate exemplary transition radii 8 between a main bearing journal 6 and a crank web 7, in the case of which the impact hardening has been performed at different impact angles α and in the case of which the impact impressions 28 of an impact head 21 of the impact tool 16 overlap along the transition radius 8 running in annularly encircling fashion around a main bearing journal 6. As already mentioned above, during a subsequent impact, the impact head 21 may at least partially penetrate into the impact impression 28 of the preceding impact, giving rise to the track of impact impressions 28 illustrated in the figures.

[0193] In FIGS. 12 and 13, for the purposes of the illustration in the figures, the impact impressions 28 run with a clearly visible offset with respect to one another on the circumference of the transition radius 8. The deviation is in fact preferably only small, but nevertheless effective. The offset profile may be achieved by means of a changed impact angle α, as illustrated in FIG. 11, and/or by means of a changed point of application of the impact head 21. In the case of the transition radius 8 of FIG. 12, a smaller impact angle α was selected than in the case of the transition radius 8 of FIG. 13, that is to say the spacing d between the deflection point U.sub.P of the deflecting unit 20 and the impact head 21 of the impact tool 16 was set to be greater in the case of the method as per FIG. 12 than in the case of the transition radius 8 of FIG. 13. Accordingly, the impact impressions 28 run higher up, or closer to the crank web 7, in the case of the transition radius 8 illustrated in FIG. 13 than in the case of the transition radius 8 of FIG. 12.

[0194] The tracks, illustrated in FIGS. 12 and 13, of impact impressions 28 have been formed in the exemplary embodiments through the use (not illustrated in any more detail here) of multiple impact heads 21 in each case. In the context of the invention, provision may even be made for an impact device 1 to have multiple impact tools 16, for example two impact tools 16, which have in each case one impact head 21 and which are assigned to the same transition radius 8, wherein the respective impact angle α of the impact tools 16 is set differently. It is then for example also possible to form tracks of impact impressions 28 which run parallel to one another (in overlapping or non-overlapping fashion).

[0195] Provision may also be made whereby, during the impact hardening of a transition radius 8, the impact angle α of an impact tool 16 is varied along the respective transition radius 8 running in annularly encircling fashion around the connecting-rod bearing journal 5 and/or main bearing journal 6. This is illustrated in FIG. 14 and may self-evidently be provided even if multiple impact heads 21 are assigned to the transition radius.

[0196] Provision may be made whereby all transition radii 8 between connecting-rod bearing journals 5 and the crank webs 7 are impact-hardened with a first impact angle α and all transition radii 8 between the main bearing journals 6 and the crank webs 7 are impact-hardened at a second impact angle α.

[0197] Alternatively, provision may be made whereby at least two transition radii 8 between the connecting-rod bearing journals 5 and the crank webs 7 are impact-hardened at a different impact angle α, and/or whereby at least two transition radii 8 between the main bearing journals 6 and the crank webs 7 are impact-hardened at a different impact angle α, and/or whereby at least one transition radius 8 between the connecting-rod bearing journal 5 and the crank webs 7 is impact-hardened at a different impact angle α, than a transition radius 8 between the main bearing journals 6 and the crank webs 7.