DE102017113072B4 - Method and device for impact hardening of transition radii of a crankshaft - Google Patents

Abstract

Device for impact hardening of transition radii (8) of a crankshaft (4), in particular transition radii (8) between connecting rod 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), comprising at least one impact device (1) with an impact piston (23), a deflection unit (20) and at least one impact tool (16), the impact piston (23) applying a force to the at least one impact tool via the deflection unit (20) (16) transmits, wherein an impact head (21) of the at least one impact tool (16) introduces an impact force (FS) into the at least one transition radius (8) at an impact angle (α), the device being set up to measure the distance (d ) between a deflection point (UP) of the deflection unit (20) and the front end of the impact head (21) of the at least one impact tool (16), characterized in that the length of the at least one impact tool (16) adjustable, preferably telescopic.

Description

The invention relates to a device for impact strengthening transition radii of a crankshaft, in particular transition radii between connecting rod journals and crank webs and / or transition radii between main bearing journals and the crank webs of the crankshaft according to the preamble of claim 1.

The invention also relates to a method for impact strengthening transition radii of a crankshaft.

The invention also relates to a crankshaft.

Due to the steadily advancing development and increase in performance of internal combustion engines and the emission requirements placed on them, today's engines are consequently subject to ever greater demands. For this reason, the engine industry places high demands on the strength of the heavily loaded crankshaft, which is important for the function of an internal combustion engine. In terms of design, there is often the requirement that the crankshaft should be light and the space required should be small. For the design of the crankshaft, this means that an increase in the load capacity should not be achieved by increasing the cross-section, i.e. by means of the moment of resistance of the crankshaft, but, if possible, by means of local compressive residual stresses. For this reason, modern crankshafts are manufactured using a wide variety of machining and heat treatment processes, so that the crankshafts can be exposed to ever higher engine outputs.

Examples of such processes are thermal treatments, such as the surface hardening processes induction and case hardening, laser hardening or nitriding, as well as work hardening processes such as deep rolling, shot peening or impact hardening. These are common and, for the most part, well-engineered processes that are suitable for a wide variety of purposes.

With regard to examples of such processes, reference is made to the following publications: EP 1 479 480 A1 , EP 0 788 419 B1 , EP 1 612 290 A1 , DE 10 2007 028 888 A1 and EP 1 034 314 B1 .

In particular, impact hardening is an advantageous method for increasing the fatigue strength, in particular the flexural fatigue strength and the torsional fatigue strength, of crankshafts. The increase in fatigue strength is achieved by applying impact forces to the crankshaft in the stressed areas at cross-sectional transitions and changes in cross-section by cold forming, preferably hammering using special impact tools. As an example of such a method, reference is made to the DE 34 38 742 C2 and the EP 1 716 260 B1 referenced.

The prior art is also referred to DE 10 2006 058 710 A1 referenced, which discloses a machine tool for impact strengthening the cheek radius transitions of crankshafts for internal combustion engines. Provision is made for the crankshaft to be rotating during the introduction of the pulse.

In addition to the general background, that is EP 3 173 158 A1 mentioned, which relates to an impact hardening device which can be used for inducing work hardening of a surface of a workpiece.

The present invention is based on the object of further developing the methods and devices for impact strengthening in order to further improve the fatigue strength of crankshafts.

This object is achieved for the device by the features listed in claim 1 and for the method by the features listed in claim 7.

Finally, the invention is also based on the object of providing a crankshaft which is improved, in particular with regard to its fatigue strength.

With regard to the crankshaft, the object is achieved by the features listed in claim 9.

The dependent claims and the features described below relate to advantageous embodiments and variants of the invention.

The device according to the invention for impact hardening of transition radii of a crankshaft, in particular transition radii between connecting rod journals and crank webs and / or transition radii between main bearing journals and the crank webs of the crankshaft, comprises at least one impact device with an impact piston, a deflection unit and at least one impact tool. The percussion piston transmits a force impulse to the at least one percussion tool via the deflection unit, a percussion head of the at least one percussion tool introducing an impact force into the at least one transition radius at an impact angle.

The connecting rod journals and the main bearing journals are shown below for the sake of simplicity sometimes just referred to as "cones". The term journal can refer to the connecting rod journals and the main bearing journals as well as just the connecting rod journals or only the main bearing journals. Unless explicitly stated otherwise, the term pin encompasses all three variants here.

The invention is particularly preferably suitable for increasing the fatigue strength of, for example, crankshafts with a length of 0.2 to 8 m or more and / or main and connecting rod journal diameters of 30 to 500 mm or more. However, the invention is particularly suitable for increasing the fatigue strength of large crankshafts of 1.5 to 8 m in length or more and / or main and connecting rod journal diameters of 100 to 500 mm or more.

The crankshaft can have different types of transition radii, for example hollow fillets, for example in the shape of a cage, or also undercut or backed radii or radii with transitions. The transition radii can, for example, merge tangentially into the bearing journal points or running surfaces of the main and connecting rod journals.

This also applies to transitions to flanges, spigots and other geometric changes in cross-section - both for tangent and stored radii.

The crankshaft usually has transition radii at all transitions or changes in cross-section. This applies in particular to changes in the cross-section between the bearing journal and the crank webs. The invention is particularly suitable for this. However, transition radii can also be used for any other changes in cross-section, in particular for changes in cross-section at the end sections of the crankshaft, e.g. B. in a transition to a flange, a disc or a shaft, etc., be provided. A transition radius whose fatigue strength is to be improved by the method according to the invention or the device according to the invention does not necessarily have to be between a connecting rod journal and a crank arm or a main bearing journal and a crank arm, but can be arranged at any point on the crankshaft. The terms “connecting rod journal”, “main bearing journal”, “flange”, “journal” and / or “crank web” can accordingly be reinterpreted by a person skilled in the art.

The invention is described below essentially on the basis of the consolidation of transition radii between the connecting rod journal and the crank web and / or the main bearing journal and the crank web. However, this is not to be understood as restrictive and is only intended to improve understanding and readability. Insofar as reference is made to a transition radius within the scope of the invention, it can in principle be any transition radius at any point on the crankshaft.

The introduction of an impact force can be understood to mean that an impact head of an impact tool or a so-called “striker” of the impact device strikes the area of the crankshaft to be solidified, in the present case a transition radius. The impact takes place in a targeted manner at the desired impact position along the transition radius running in a ring around the pin. For this purpose, a percussion piston can be used, which transmits a strong impulse or a force impulse (e.g. generated pneumatically, hydraulically and / or electrically) to the percussion head.

Depending on the impact force, visible impact impressions of the impact head are created at the respective impact positions. The depth of the impact impressions and the quality or the depth effect of the residual compressive stress that is introduced depend on the selected impact force. The tool and the process parameters are preferably precisely matched to the respective crankshaft and, if necessary, to partial geometric changes (changes in cross section).

The impact force, in turn, can be individually adjusted or aligned even more precisely to the stress maximum by changing the impact angle.

The device can optionally have several striking devices.

According to the invention, the device is set up to adjust the distance between a deflection point of the deflection unit and the front end of the impact head of the at least one impact tool.

The deflection point can be the center point of the deflection unit or the axis of rotation / suspension of the striking tool or the striking tools.

The front end of the impact head means that part (or the surface) of the impact head with which the impact head strikes against the crankshaft for impact hardening.

Through the The distance between the deflection point and the front end of the impact head can also be adjustable, the distance between the deflection point and the center point of the impact head or the distance between the deflection point and the rear end of the impact head.

Because the distance between the deflection point of the deflection unit and the impact head is adjustable, the angle at which the impact force is introduced into the transition radius can be changed or adjusted. The angle is preferably selected in such a way that the impact force is introduced at an angle which is precisely adapted to the point that is subjected to the highest load during operation of the crankshaft or to the maximum load.

The solution according to the invention makes it possible to apply the impact force at a preferred point and at a preferred angle.

The methods and devices according to the prior art provide that when a transition radius is impact hardened, the impact force is introduced into the transition radii at a predefined fixed angle. A striking angle of approx. 45 ° is usually provided for this.

Depending on the application of the crankshaft, it can be advantageous to choose a different angle instead of a fixed flapping angle of 45 °, for example.

The most heavily loaded point on the crankshaft generally results from engine operation or is determined using calculation models. For new approaches, the maximum loads from uniaxial loading and from biaxial, superimposed loading are considered.

The method according to the invention and the device according to the invention can ensure high-precision work or impact hardening. Because the impact forces can be specifically introduced into a stress maximum of the transition radius and run at an optimal angle, the impact force can optionally be reduced while the achievable fatigue strength effect remains unchanged. The device according to the invention is therefore particularly efficient.

Depending on the application, the fatigue strength of the crankshaft - based on the current possibilities in the prior art - can even be increased by the targeted introduction of the impact forces, should this be necessary.

The method according to the invention or the device according to the invention can also be applied or used with crankshafts which have already been processed beforehand by other methods to increase their fatigue strength properties. For example, a crankshaft that has been hardened by induction hardening can subsequently be improved in terms of its flexural and torsional fatigue strength by introducing internal compressive stresses with the device according to the invention or the method according to the invention.

According to the invention it is provided that the length of the at least one striking tool is adjustable, preferably telescopic.

For this purpose, the striking tool can be designed in the manner of a telescopic rail or have a telescopic extension. The at least one striking tool can also be designed as a telescopic tube. The invention is of course not to be understood as being restricted to a specific type of telescopic extension or a specific type of telescoping capability.

The length of the at least one striking tool can, for example, also be adjusted via a thread.

It can be provided that the length of the at least one striking tool can be adjusted manually and / or by actuators. For this purpose, for example, an electric motor, in particular a linear drive, can be provided. In principle, however, the electric motor can be any desired electric motor, for example a three-phase motor, an alternating current motor, a direct current motor or a universal motor. A stepper motor can preferably be used.

In a further development of the invention, a changing device with a magazine can be provided in order to exchange the at least one striking tool and / or the striking head and / or the deflection unit and / or the striking device in order to reduce the distance between the deflection point of the deflection unit and the front end of the striking head to set the at least one impact tool to a different value.

As a result of the high impact forces, it is known that high mechanical loads act on the components of the impact device. In particular, when using filigree components to adjust the length of the at least one striking tool, the service life of the striking device or its components can be limited as a result. If a magazine or a changing device is provided for the at least one striking tool and / or the striking head and / or the deflection unit and / or the striking device, the striking device or the device as a whole can be particularly robust, since if necessary, the at least a striking tool can be dispensed with.

The distance between the deflection point of the deflection unit and the striking head of the at least one striking tool can thus advantageously be adjusted by the changing device with the magazine by replacing components of the striking device for length adjustment.

It can also be provided that the distance between the deflection point of the deflection unit and the front end of the impact head of the at least one impact tool can be adjusted by using spacer rings or spacers with different dimensions.

In a further development of the invention, two or more impact devices can be provided, the distance between the deflection point of the deflection device and the front end of the impact head of a first impact device not being identical to the distance between the deflection point of the deflection device and the front end of the impact head of a second impact device .

Several striking tools that can be used independently of one another, in particular by using several striking devices, each with one or more striking tools, can thus be provided, which are capable of introducing the respective striking forces into any transition radii of the crankshaft, whereby a corresponding synchronization with one another or between controls of the striking tools can be provided. The impact hardening of the crankshaft can thus also take place particularly quickly, since several impact devices can be used at the same time.

In a further development of the invention it can be provided that the at least one striking device has two striking tools, the striking tools being arranged on the deflection unit in such a way that each striking tool is assigned to a transition radius.

It can therefore be provided that two striking tools are used in a common striking device, which preferably bring striking forces into both transition radii of a connecting rod journal or a main journal at the same time.

This also applies to transitions to flanges, spigots and other geometric changes in cross-section - both for tangent and stored radii.

The striking tools can preferably be operated by a common striking piston.

When using several striking tools and / or striking devices, a common pressure pulse device can be provided which is able to generate the corresponding striking forces for the striking tools in a hydraulic, pneumatic, mechanical and / or electrical manner (jointly or individually) for the striking tools.

When using several striking devices it can be provided that the respective distances between the deflection points and the striking heads are identical for all striking tools or differ from one another with at least two striking tools. The respective distance between the deflection point of the deflection unit and the striking heads of two striking tools that are used for solidifying transition radii that adjoin the same pin is preferably identical.

In a further development of the invention it can be provided that the impact angle between the longitudinal axis of the at least one impact tool and a perpendicular to the longitudinal axis of the crankshaft is 5 ° to 80 °, preferably 10 ° to 70 °, more preferably 20 ° to 60 ° and particularly preferably 30 ° to 55 °, in particular 35 ° to 50 °.

A lay angle of 45 ° can preferably be provided, especially if the maximum stress is not precisely known.

In a further development of the invention it can also be provided that the impact head has a radius whose size is 75% to 99% of the transition radius, preferably 85% to 98% of the transition radius and particularly preferably 85% to 95% of the transition radius.

However, the radius of the impact head can also be smaller than 75% of the transition radius or greater than 95% of the transition radius. The radius of the impact head can also match the transition radius.

The impact head can preferably be designed essentially spherically, in particular in the front area or at the front end of the impact head, which strikes against the crankshaft for solidification. In principle, however, the impact head can have any geometry and, for example, can also be oval, hemispherical or flat.

The invention also relates to a method for impact strengthening transition radii of a crankshaft, in particular transition radii between connecting rod journals and crank webs and / or transition radii between main bearing journals and the crank webs of the crankshaft.

The method also applies to transitions to flanges, journals and other geometric changes in cross-section - both for tangent and stored radii.

Features that have already been described in connection with the device according to the invention can of course also be advantageously implemented for the method according to the invention - and vice versa. Furthermore, advantages that have already been mentioned in connection with the device according to the invention can also be understood in relation to the method according to the invention - and vice versa.

In a further development it can be provided that the flap angle is selected according to the course of a stress maximum of the transition radius, after which the course of the stress maximum is determined on the basis of simulations and / or calculations and / or test series of the respective crankshaft type.

The most heavily loaded points on the crankshaft are preferably identified in advance. By means of the device according to the invention or the method according to the invention, the impact force can then be brought into the corresponding stress maxima in a targeted manner. By taking into account the individual requirements for different types of crankshafts and uses of the crankshafts, the crankshaft can be impact-hardened with particularly high precision by setting the distance according to the invention between the deflection point of the deflection unit and the front end of the impact head of the at least one impact tool.

By means of the method and the device according to the invention, not only the point of impact but also the direction of impact can be determined. In this way, crankshafts can be produced whose fatigue strength, in particular their flexural and torsional fatigue strength, is further optimized. Alternatively, with the precision that is now available, an existing fatigue strength can already be achieved through the use of low impact forces.

All transitions to flanges, journals and / or other geometric changes in cross-section - both for tangential and stored radii - can be impact hardened at the same impact angle.

It can be provided that all transition radii of the crankshaft are impact hardened at the same impact angle, the impact angle selected for this purpose being optimized with regard to the most heavily loaded point on the crankshaft. However, it can also be provided that all transition radii of the connecting rod journals are impact hardened at a first impact angle and all transition radii of the main bearing journals are impact strengthened at a second impact angle, the first and the second impact angle being optimized according to the highest stressed points or the course of the maximum stress .

In the method according to the invention it is provided that at least two transition radii between the connecting rod journal and the crank webs are impact strengthened at a different impact angle and / or that at least two transition radii between the main bearing journal and the crank webs are impact strengthened at a different impact angle and / or that at least one transition radius between the connecting rod journal and the crank webs is impact hardened at a different angle of impact than a transition radius between the main bearing journal and the crank webs.

The flapping angles can thus be defined or optimized individually for each transition radius or for groups of transition radii.

For example, different angles of impact can be used at the same time in one tapping point.

In the method according to the invention, it is alternatively or additionally finally also provided that during the impact hardening of a transition radius encircling the connecting rod journal and / or the main bearing journal, the impact angle is changed.

Of course, this also applies to transitions to flanges, journals and / or other geometric changes in cross-section - both for tangent and stored radii.

It has been shown that a further increase in fatigue strength or alternating bending strength and / or alternating torsional strength can be achieved in this way.

For example, in the so-called bottom dead center of a connecting rod journal or in a defined area around the bottom dead center, a different angle of impact can be provided than in the remaining area of the transition radius.

The impact pressures that are converted by the impact piston into the impact force can - depending on the operation - be between 10 and 300 bar, preferably between 30 and 180 bar, and particularly preferably between 50 and 130 bar.

The temperature in the area of the crankshaft segment or transition radius to be machined should preferably not be higher than 65 ° C; Values between 12 ° C and 25 ° C are preferred.

Experience has shown that crankshafts can develop microcracks on the surfaces that are not capable of spreading after dynamic stress in the engine or on the test bench. These microcracks have no effect on the fatigue strength properties, but they can disrupt the visual appearance.

Since residual compressive stress can preferably be introduced up to a depth of 15 mm, but also even deeper, this means that a few millimeters, for example 0.1 to 3 mm, preferably 0.5 mm, can be removed in the surface area of the crankshaft , take place without the flexural and torsional fatigue strength or the fatigue strength of the crankshaft suffering.

Studies have shown that such measures can even slightly increase the fatigue strength, for example by up to 5%.

The surface can be removed in various ways, for example by grinding, turning, milling, turning milling, peeling or polishing.

In particular if it is provided that the impact angle is changed by an actuator during the impact hardening of a transition radius, a control and / or regulating device, preferably comprising a microprocessor, can be provided in order to control the corresponding actuator system.

Instead of a microprocessor, any other device for implementing a control and / or regulating device can also be provided, for example one or more arrangements of discrete electrical components on a circuit board, a programmable logic controller (PLC), an application-specific integrated circuit (ASIC) or another programmable circuit, for example also a field programmable gate array (FPGA), a programmable logic arrangement (PLA) and / or a commercially available computer.

Some of the components of the device according to the invention can basically in their structure of the device according to the EP 1 716 260 B1 correspond, which is why the disclosure content of the EP 1 716 260 B1 be fully integrated into the present disclosure by referencing.

The invention also relates to a crankshaft produced by a method described above.

The crankshaft according to the invention differs from conventional crankshafts in particular in that at least two different impact angles are used for their consolidation, which results in a characteristic consolidation of the transition radii.

Exemplary embodiments of the invention are described in more detail below with reference to the drawing.

The figures each show preferred exemplary embodiments in which individual features of the present invention are shown in combination with one another. Features of an exemplary embodiment can also be implemented separately from the other features of the same exemplary embodiment and can accordingly be easily combined with features of other exemplary embodiments by a person skilled in the art to form further useful combinations and subcombinations.

In the figures, functionally identical elements are provided with the same reference symbols.

• 1 eine Gesamtansicht einer erfindungsgemäßen Vorrichtung zur Durchführung des Verfahrens in einer ersten Ausführung;
• 2 eine perspektivische Ansicht eines Teils der erfindungsgemäßen Vorrichtung zur Durchführung des Verfahrens in einer zweiten Ausführung;
• 3 eine Schlageinrichtung mit zwei Schlagwerkzeugen in vergrößerter Darstellung gemäß Einzelheit „A“ aus 1;
• 4 eine Schlageinrichtung mit zwei teleskopierbaren Schlagwerkzeugen;
• 5 eine vergrößerte Darstellung eines Übergangsradius und eines Schlagwerkzeugs mit einem Schlagkopf, wobei das Schlagwerkzeug auf einen ersten Schlagwinkel ausgerichtet ist;
• 6 eine vergrößerte Darstellung eines Übergangsradius und eines Schlagwerkzeugs mit einem Schlagkopf, wobei das Schlagwerkzeug auf einen zweiten Schlagwinkel ausgerichtet ist;
• 7 einen schlagverfestigten Übergangsradius, bei dem ein erster Schlagwinkel zur Schlagverfestigung verwendet wurde;
• 8 einen schlagverfestigten Übergangsradius, bei dem ein zweiter Schlagwinkel zur Schlagverfestigung verwendet wurde; und
• 9 einen schlagverfestigten Übergangsradius, bei dem der Schlagwinkel während der Schlagverfestigung entlang des ringförmig um den Zapfen umlaufenden Übergangsradius variiert wurde.

They show schematically:

• 1 an overall view of a device according to the invention for performing the method in a first embodiment;
• 2 a perspective view of part of the device according to the invention for performing the method in a second embodiment;
• 3 a striking device with two striking tools in an enlarged view according to detail "A" 1 ;
• 4th a striking device with two telescopic striking tools;
• 5 an enlarged view of a transition radius and a striking tool with a striking head, wherein the striking tool is aligned with a first striking angle;
• 6th an enlarged view of a transition radius and a striking tool with a striking head, wherein the striking tool is aligned with a second striking angle;
• 7th an impact strengthened transition radius at which a first impact angle was used for impact strengthening;
• 8th an impact strengthened transition radius where a second impact angle was used for impact strengthening; and
• 9 an impact hardened transition radius, in which the impact angle was varied during the impact hardening along the transition radius surrounding the journal in a ring shape.

In the 1 The device shown in an overall view basically corresponds in its structure to the devices according to FIG DE 34 38 742 C2 and EP 1 716 260 B1 with one or more impact devices 1 , which is why only the essential parts and the differences to the prior art are discussed in more detail below.

The device has a machine bed 2 and a drive device 3 on. The drive device 3 is used to make a crankshaft 4th to bring or rotate along a direction of rotation in a striking position.

The crankshaft 4th has connecting rod journals 5 and main journals 6th , between which each crank web 7th are arranged on. Between connecting rod journals 5 and crank webs 7th as well as between main bearing journals 6th and crank webs 7th or generally between cross-sectional transitions of the crankshaft 4th are transition radii 8th (see. 3 and 5 to 9 ) educated.

At the drive device 3 facing side of the crankshaft 4th is a fastening device 9 provided that has a tension washer or a mounting flange 10 having. On the drive device 3 facing away from the crankshaft 4th is a support 11 preferably provided in the manner of a tailstock, which has a further fastening device 9 has to the crankshaft 4th rotatably pick up or set rotatable. Optional or in addition to the support 11 a steady rest, which is positioned at a rotationally symmetrical point, can be provided.

The drive device 3 the crankshaft is capable of 4th along an axis of rotation C. to put in a rotary motion. It can be provided that the main axis of rotation C _KW the crankshaft 4th off-center from the axis of rotation C. the drive device 3 is positioned as in 1 and 2 shown. Alignment means can preferably be used for this purpose 17th (see. 2 ) in the area of the fastening device 9 be provided. It can be provided that the alignment means 17th a central axis of the respective pin to be solidified 5 , 6th Shift so that the central axis of the tenon 5 , 6th on the axis of rotation C. lies.

For the drive device 3 a direct drive, preferably without a clutch, can be provided. A motor, preferably an electric motor, of the drive device 3 can thus without translation or gear with the fastening device 9 or with the crankshaft 4th be mechanically coupled. An input shaft can be used to transmit the drive power 13th or a drive shaft can be provided.

The impact devices described in more detail below by way of example 1 are each in a shifting and adjusting device 15th kept adjustable to match the location of the connecting rod journals 5 and the main journal 6th and to the length of the crankshaft 4th adapt.

Also the support 11 can be designed to be displaceable, as indicated by the double arrows in 1 indicated.

In the 1 are two impact devices 1 shown, but in principle any number of impact devices 1 be provided, for example, only a single impact device 1 .

For the operation of the drive device 3 , which preferably comprises an electric motor, a position control can be used to control the crankshaft 4th to turn into the respective striking position, after which the crankshaft 4th is preferably rotated step by step or clocked.

Having a transition radius 8th has been impact strengthened in the desired manner, the or can the impact devices 1 to the transition radii to be hardened next 8th be moved.

In 2 a further device for carrying out the method according to the invention is shown in a perspective view, but without an impact device. The device of the 2 is essentially identical to the device of 1 , which is why only the essential differences are referred to in detail below.

Again is a propulsion device 3 intended. There is also a fastening device 9 provided that has a mounting flange 10 and an attached face plate with clamping jaws for fixing the crankshaft 4th having. The faceplate with the clamping jaws of the fastening device 9 is on the mounting flange 10 adjustable on an alignment means 17th arranged, whereby the longitudinal axis C _KW the crankshaft 4th relative to the axis of rotation C. a drive shaft or an input shaft 13th can move.

The crankshaft 4th the 2 has one of the in 1 Embodiment shown has a different configuration, but includes basically also connecting rod journals 5 , Main journal 6th and crank webs 7th .

In 2 (as in 1 ) can be connected to that of the drive device 3 remote end of the crankshaft 4th another fastening device 9 be provided, but this can also be omitted.

In 3 is an example of a striking device 1 the 1 shown in more detail. The invention can in principle with any impact device 1 implemented. The impact device described below 1 however, it is particularly suitable. It has a basic body 18th on, which can be provided with a prismatic system and preferably guides according to the radius of the crankshaft segment to be machined 19th has, the two striking tools 16 lead in their support plane and them in the support angle or impact angle α (see. 4th to 6th ) around a deflection unit 20th give a corresponding freedom to adapt to the dimensional relationships of the crankshaft 4th is beneficial. At the front ends of the two striking tools 16 is a ball as a striking head 21 arranged. An intermediate part 22nd provides the connection between a percussion piston 23 and the deflection unit 20th that transfer the impact energy to the impact tools 16 passes on, here. The intermediate part 22nd can also be omitted if necessary.

To increase the effectiveness of the blow can be done on the body 18th remote side of the pin 5 , 6th a clamping prism 24 about feathers 25th with adjustable clamping bolts 26th with clamping nuts 27 attached. Other constructive solutions are also possible here.

By arranging several striking devices 1 over the length of the crankshaft to be machined 4th If necessary, all centrically and possibly eccentrically extending areas of the crankshaft can be used 4th can be edited at the same time.

According to the invention, the percussion piston transmits 23 via the deflection unit 20th an impulse of force on the striking tools 16 after which the hammer heads 21 the striking tools 16 at a flapping angle α an impact force F _S in the transition radii 8th bring in. It is provided that the distance d (cf. 4th ) between the turning point U _P the deflection unit 20th and the front end of the respective impact head 21 the striking tools 16 is adjustable.

The expression “F _S ” and comparable expressions in the present description are only to be understood as placeholders / variables for any type of impact that appears appropriate to a person skilled in the art. _{If “the impact force F S} ” is referred to in the description, the impact forces can therefore be different or else identical.

In 3 the technical solution for setting the distance d is shown only in a highly schematic manner. For example, it can be a changing device 30th be provided with a magazine to the at least one striking tool 16 and / or the impact head 21 and / or the deflection unit 20th and / or the at least one striking device 1 exchange to the distance d between the turning point U _P the deflection unit 20th and the front end of the impact head 21 of the at least one striking tool 16 set to another value. In 3 becomes a changing facility 30th for exchanging striking tools 16 indicated. The changing facility 30th includes a selection of striking tools for this purpose 16 each with a different length. By exchanging a striking tool 16 can be the distance d and thus the angle of impact α can be set.

It can also be provided that the length of the striking tools 16 adjustable, preferably telescopic. A corresponding structure is in 4th shown. 4th shows a section of a striking device 1 , which can be formed essentially identically as in the embodiment of FIG 3 .

In 4th are two telescopic impact tools 16 shown schematically. Due to the adjustable length of the striking tools 16 is the distance d between the turning point U _P the deflection unit 20th and the front end of the impact head 21 adjustable. In this way, the flapping angle can also be indirectly determined α and possibly also influence the stroke position.

It can also, as in 1 shown, be provided several striking devices 1 to use. The respective distance d between the deflection point is then preferably U _P and the impact head 21 at least with two striking devices 1 not identical. This enables the striking devices 1 each for impact strengthening of a transition radius 8th or a group of transition radii 8th to use, with the striking tools 16 the respective impact device 1 in each case already on the preferably intended flapping angle α are set. A conversion of the impact device 1 is therefore not necessary. So far the crankshaft 4th only transition radii 8th with two different advantageous striking angles α therefore preferably two appropriately preset striking devices are sufficient 1 .

It can e.g. B. be provided that a first Impact device 1 Impact forces F _S at a first impact angle α ₁ and a second impact device 1 Brings impact forces F _S at a second impact angle α ₂ . Impact devices can also be used 1 are used, where the distance d or the angle of impact α is adjustable in different ways. A conventional striking device with a striking device according to the invention can also be used 1 be combined.

It can be provided that the flapping angle α between the longitudinal axis L _S of the at least one striking tool 16 and a plumb bob I _KW to the longitudinal axis C _KW of the crankshaft 45 ° to 80 °, preferably 10 ° to 70 °, more preferably 20 ° to 60 ° and particularly preferably 30 ° to 55 °, in particular 35 ° to 50 °.

To clarify the relationships are in the 5 and 6th Enlargements shown, which are highly schematic of a percussion head 21 an impact tool 16 and an exemplary transition radius 8th a crankshaft 4th represent. In the example, the 5 under a first flapping angle α ₁ and in the 6th impact hardened at a second impact angle α _2.

By setting the angle of impact accordingly α via the change in the distance d between the turning point U _P the deflection unit 20th and the impact head 21 of the impact tool 16 the direction of the impact force F _S can be specified, whereby the area of greatest effectiveness of impact hardening can be set in a targeted manner.

It can also be provided _{to reduce the impact force F S in a} targeted manner or to change the direction of action, if z. B. reduced cross-sections, bores or other geometric relationships require this.

Preferably the angle of flap α according to the course of a stress maximum MAX ₁ , MAX ₂ the transition radius 8th chosen, according to which the course of the stress maximum MAX ₁ , MAX ₂ is determined on the basis of simulations and / or calculations and / or test series of the respective crankshaft type.

In 6th is the impact head 21 at the same position of the transition radius 8th positioned as with 5 . However, the distance d is between the turning point U _P the deflection unit 20th and the impact head 21 adjusted so that the impact tool 16 at a different angle α is aligned as in 5 . This results in the impact at angle α ₂ in the transition radius 8th is introduced, although the impact head 21 basically in the same position as in 5 is set.

The representation in 6th differs particularly strongly from the representation in the 5 from.

In principle, the positioning of the impact head can also be used 21 in the transition radius 8th be changed, ie the impact head 21 could possibly also at a different position along the circumference of the transition radius 8th start, at the same time the flapping angle α can be changeable.

The impact head 21 can have a radius r _s , the size of which is 75% to 99% of the transition radius 8th , preferably 85% to 98% of the transition radius 8th and particularly preferably 85% to 95% of the transition radius 8th amounts to. _{The radius r s} preferably corresponds to the impact head 21 the transition radius 8th essentially.

In the 7th and 8th are exemplary transition radii 8th between a main journal 6th and a crank web 7th shown in which the impact hardening at different impact angles α has taken place and in which the impact impressions 28 of a striking head 21 of the impact tool 16 along the ring around a main bearing journal 6th circumferential transition radius 8th overlap. The impact head penetrates 21 in the case of a subsequent impact, at least partially in the impact impression 28 of the previous blow, which creates the "trace" shown in the figures from blow impressions 28 arises.

In the 7th and 8th run the impact impressions 28 for the illustration clearly recognizable on the circumference of the transition radius 8th offset from each other. In fact, the deviation is preferably only small, but nevertheless effective. The offset course can be achieved by changing the flapping angle α , as in 6th shown and / or by a changed starting point of the impact head 21 can be achieved. At the transition radius 8th the 7th became a smaller flapping angle α chosen than the transition radius 8th the 8, d . H. the distance d between the turning point U _P the deflection unit 20th and the impact head 21 of the impact tool 16 was in accordance with the procedure 7th set larger than the transition radius 8th the 8th . The impact impressions run accordingly 28 at the in 8th shown transition radius 8th further up or closer to the crank web 7th than this at the transition radius 8th the 7th the case is.

It can also be provided that the flapping angle α an impact tool 16 during impact hardening of a transition radius 8th along the ring around the connecting rod journal 5 and / or main bearing journals 6th circumferential respective transition radius 8th is changed. This is in 9 shown.

It can be provided that all transition radii 8th between connecting rod journals 5 and the crank webs 7th with a first flapping angle α and all transition radii 8th between the main journals 6th and the crank webs 7th under a second flapping angle α be impact strengthened.

Alternatively, it can be provided that at least two transition radii 8th between the connecting rod journals 5 and the crank webs 7th at a different flapping angle α are impact strengthened and / or that at least two transition radii 8th between the main journals 6th and the crank webs 7th at a different flapping angle α are impact strengthened and / or that at least one transition radius 8th between the connecting rod journal 5 and the crank webs 7th at a different angle α is impact hardened as a transition radius 8th between the main journals 6th and the crank webs 7th .

Claims (9)

Device for impact hardening of transition radii (8) of a crankshaft (4), in particular transition radii (8) between connecting rod 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), comprising at least one impact device (1) with an impact piston (23), a deflection unit (20) and at least one impact tool (16), the impact piston (23) applying a force to the at least one impact tool via the deflection unit (20) (16) transmits, wherein an impact head (21) of the at least one impact tool (16) introduces an impact force (F _S ) into the at least one transition radius (8) at an impact angle (α), the device being set up to measure the distance ( d) to be set between a deflection point (U _P ) of the deflection unit (20) and the front end of the striking head (21) of the at least one striking tool (16), characterized in that the length of the at least one S impact tool (16) is adjustable, preferably telescopic. Device according to Claim 1 , characterized in that a changing device (30) with a magazine is provided in order to exchange the at least one striking tool (16) and / or the striking head (21) and / or the deflection unit (20) and / or the striking device (1), in order to set the distance (d) between the deflection point (U _P ) of the deflection unit (20) and the front end of the striking head (21) of the at least one striking tool (16) to a different value. Device according to Claim 1 or 2 , characterized in that two or more impact devices (1) are provided, the distance between the deflection point (U _P ) of the deflection unit (20) and the front end of the at least one impact head (21) of a first impact device (1) is not identical with the distance between the deflection point (U _P ) of the deflection unit (20) and the front end of the at least one impact head (21) of a second impact device (1). Device according to one of the Claims 1 to 3 , characterized in that the at least one striking device (1) has two striking tools (16), the striking tools (16) being arranged on the deflection unit (20) in such a way that each striking tool (16) is assigned to a transition radius (8). Device according to one of the Claims 1 to 4th , characterized in that the impact angle (α) between the longitudinal axis (L _s ) of the at least one impact tool (16) and a perpendicular (I _KW ) to the longitudinal axis (C _KW ) of the crankshaft (4) 5 ° to 80 °, preferably 10 ° to 70 °, more preferably 20 ° to 60 ° and particularly preferably 30 ° to 55 °, in particular 35 ° to 50 °. Device according to one of the Claims 1 to 5 , characterized in that the impact head (21) has a radius (r _s ), the size of which is 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). Method for impact hardening of transition radii (8) of a crankshaft (4), in particular transition radii (8) between connecting rod 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), where a) at least two transition radii (8) between the connecting rod journals (5) and the crank webs (7) are impact strengthened at a different impact angle (α); and or b) at least two transition radii (8) between the main bearing journals (6) and the crank webs (7) are impact strengthened at a different impact angle (α); and or c) at least one transition radius (8) between the connecting rod journals (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); and or d) the impact angle (α) is changed during the impact hardening of an annular transition radius (8) around the connecting rod journal (5) and / or the main bearing journal (6). Procedure according to Claim 7 , characterized in that the flapping angle (α) is selected according to the course of a stress maximum (MAX ₁ , MAX ₂ ) of the transition radius (8), after which the course of the stress maximum (MAX ₁ , MAX ₂ ) is based on simulation and / or calculations and / or test series of the respective crankshaft type is determined. Crankshaft (4) produced by a method according to one of the Claims 7 to 8th .

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