Method and device for the impact treatment of transition radii of a crankshaft

Abstract

The invention relates to a method for the impact treatment of transition radii (8) of a crankshaft (4, 4′), in particular transition radii (8) between connecting rod bearing journals (5, 5′) and crank webs (7, 7′) and/or transition radii (8) between main bearing journals (6, 6′) and the crank webs (7, 7′) of the crankshaft (4, 4′). The crankshaft (4, 4′) is then rotated along a rotational direction into an impact position by means of a drive device (3, 3′). A locking device (12) is provided in order to lock the crankshaft (4, 4′) in the impact position, and an impact force is then introduced into at least one transition radius (8) by at least one impact tool (16, 16′).

Claims

1. 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, wherein the crankshaft is firstly rotated by means of a drive device along a direction of rotation into an impact position, wherein an arresting device is provided in order to arrest the crankshaft in the impact position, following which an impact force is introduced into at least one transition radius by means of at least one impact tool, wherein the arresting device arrests the crankshaft indirectly by virtue of the arresting device arresting a fastening flange of a rotatable fastening device, to which the crankshaft is fixed.

2. The method as claimed in claim 1, wherein for the operation of the drive device, closed-loop position control is used in order to rotate the crankshaft into the impact position.

3. The method as claimed in claim 1, wherein the controller of the drive device and the controller of the arresting device are synchronized with one another such that the arresting device arrests the crankshaft only when the crankshaft is at a standstill in the impact position.

4. The method as claimed in claim 1, wherein the controller of the arresting device and the controller of the at least one impact tool are synchronized such that the at least one impact tool introduces the impact force into the at least one transition radius of the crankshaft only when the crankshaft has been arrested in the impact position.

5. The method as claimed in claim 1, wherein the drive device is designed as a direct drive.

6. The method as claimed in claim 1, wherein the arresting device and the drive device are arranged separately from one another.

7. The method as claimed in claim 1, wherein the arresting device engages on the fastening flange in the region of an outer circumference.

8. The method as claimed in claim 1, wherein the arresting device is designed to prevent rotation of the crankshaft counter to and/or in the direction of rotation of the crankshaft.

9. The method as claimed in claim 1, wherein the impact hardening is performed in such a way that the impact impressions of an impact head of the impact tool overlap in a defined manner along the respective transition radius running in annularly encircling fashion around the connecting-rod bearing journal and/or main bearing journal.

10. The method as claimed in claim 1, wherein the at least one impact tool performs an impact movement or introduces the impact force with a periodicity.

11. The method as claimed in claim 1, wherein the crankshaft is rotated preferably in stepped or clocked fashion.

12. The method as claimed in claim 1, wherein the drive device is designed without a clutch.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) Exemplary embodiments of the invention will be described in more detail below on the basis of the drawing.

(2) 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.

(3) In the figures, functionally identical elements are denoted by the same reference designations.

(4) In the figures, in each case schematically:

(5) FIG. 1 shows an overall view of an apparatus according to the invention for carrying out the method in a first embodiment;

(6) FIG. 2 shows a flow diagram of the method according to the invention;

(7) FIG. 3 shows a perspective view of a part of the apparatus according to the invention for carrying out the method in a second embodiment;

(8) FIG. 4 shows an impact device with two impact tools in an enlarged illustration as per the detail “A” from FIG. 1;

(9) FIG. 5 shows an impact device with only one impact tool; and

(10) FIG. 6 shows an impact-hardened transition radius in the case of which impact impressions of an impact head overlap along the annularly encircling transition radius.

DETAILED DESCRIPTION OF THE INVENTION

(11) 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.

(12) 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.

(13) 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. 4 to 6) 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.

(14) 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 tailstock 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.

(15) According to the invention, an arresting device 12 is provided, which engages in the region of an outer circumference of the fastening device 9. Basically, the arresting device 12 may be arranged at any desired location within the apparatus in order to apply an arresting force to an output shaft of the drive device 3, or to an input shaft 13, which in the present case is identical to said output shaft, of the fastening device 9, and thus to the crankshaft 4. The arresting device 12 may also engage on multiple locations of the apparatus. By way of example, a second part of the arresting device 12 in engagement with the fastening device 9 in the region of the support 11 is illustrated by dashed lines.

(16) The arresting device 12 is based for example on a non-positive arresting action using a merely schematically illustrated brake shoe arrangement 14.

(17) 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. 3. For this purpose, it is preferably possible for alignment means 17 (see FIG. 3) 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, 5′, 6, 6′ that is respectively to be hardened such that the central axis of the journal 5, 5′, 6, 6′ lies on the axis of rotation C.

(18) A direct drive, preferably without a clutch, is in particular 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.

(19) 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.

(20) The support 11 may also be designed to be displaceable, as indicated by the double arrows in FIG. 1.

(21) 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.

(22) FIG. 2 illustrates a method which is basically composed of four steps (rotating, arresting, impacting, releasing).

(23) 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.

(24) After the crankshaft 4 has been rotated by the drive device 3 into the impact position, the crankshaft 4 is initially arrested in the impact position by the arresting device 12.

(25) Subsequently, an impact force is introduced into at least one transition radius 8 of the crankshaft 4 by means of at least one impact tool 16 (cf. FIG. 4 and FIG. 5).

(26) Preferably, the controller of the drive device 3 and the controller of the arresting device 12 are synchronized with one another such that the arresting device 12 arrests the crankshaft 4 only when the crankshaft 4 is at a standstill in the impact position.

(27) Furthermore, it is also possible for the controllers of the arresting device 12 and of the at least one impact tool 16 (or of the at least one impact device 1) to be synchronized such that the at least one impact tool 16 introduces the impact force into the transition radius 8 of the crankshaft 4 only when the crankshaft 4 has been arrested in the impact position. The arresting of the crankshaft 4 is subsequently released again.

(28) The method may subsequently be repeated as often as desired along a transition radius 8, preferably for one complete rotation along the circumference of the transition radius 8 or along the annularly encircling transition radius 8. It is also possible for more than one rotation to be provided, for example 2 or 3 rotations. However, there is no need for a complete rotation to be performed.

(29) After a transition radius 8 has been impact-hardened in the desired manner, the impact tool 16, or the entire impact device 1, can be moved to the next transition radius 8 that is to be hardened, following which the method (rotating, arresting, impacting, releasing) can be repeated along the next transition radius 8 running in annularly encircling fashion around the journal.

(30) The at least one impact tool 16 or the at least one impact device 1 may introduce the impact movement or the impact force with a periodicity, for example with a timing of 0.1 Hz to 50 Hz, preferably with a timing of 0.3 Hz to 10 Hz, particularly preferably with a timing of 0.5 Hz to 5 Hz and very particularly preferably with a timing of 0.5 Hz to 3 Hz.

(31) An open-loop and/or closed-loop control device 29, preferably comprising a microprocessor, may be provided for carrying out the method. The open-loop and/or closed-loop control device 29 may for example also comprise or implement and/or synchronize the controllers of the drive device 3, of the arresting device 12 and/or of the at least one impact tool 16.

(32) In particular, a computer program with program code means may be provided in order to carry out the method according to the invention when the program is executed on an open-loop and/or closed-loop control device 29, in particular on a microprocessor.

(33) FIG. 3 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. 3 is substantially identical to the apparatus of FIG. 1, for which reason only the important differences will be referred to in detail below.

(34) A drive device 3′ is once again provided. In the embodiment of FIG. 3, the arresting de-vice is however arranged (in a manner which is not visible) within the drive device 3′. Although the arresting device is preferably arranged as illustrated in FIG. 1, the arresting device may thus also be accommodated within the drive device 3′. Here, however, provision is nevertheless made whereby the arresting device is activatable separately from the drive device 3′. The arresting device is, in FIG. 3, not a constituent part of the drive device 3′. The drive device 3′ may possibly additionally have a dedicated brake device.

(35) 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 the drive shaft 13′.

(36) The crankshaft 4′ of FIG. 3 has a configuration which deviates from the crankshaft 4 in FIG. 1, but basically likewise comprises connecting-rod bearing journals 5′, main bearing journals 6′ and crank webs 7′.

(37) In FIG. 3 (as in FIG. 1), a further fastening device 9, 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.

(38) An impact device 1 of FIG. 1 is illustrated in more detail by way of example in FIG. 4. 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 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.

(39) 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.

(40) 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.

(41) FIG. 5 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′, 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 tool in a standing position.

(42) 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.

(43) FIG. 6 illustrates an exemplary transition radius 8 between a main bearing journal 6 and a crank web 7, in the case of which the impact hardening has been performed such that the impact impressions 28 of an impact head 21 of the impact tool 16, 16′ overlap along the transition radius 8 running in annularly encircling fashion around a main bearing journal 6.

(44) To achieve this type of impact hardening, highly precise working or operation of the apparatus is necessary.

(45) In particular if the impact spacings are set to be narrow, it is the case during a subsequent impact that the impact head 21 penetrates at least partially into the impact impression 28 of the preceding impact, whereby the impact force can exert a resetting rotational action on the crankshaft 4, 4′. The arresting device 12 may be designed to prevent such a rotational movement. It may in particular be advantageous for the arresting device 12 to be designed to prevent rotation of the crankshaft 4, 4′ counter to the direction of rotation of the drive device 3, 3′.

(46) Provision may also be made whereby at least one impact device 1 is designed and configured for the impact hardening of the transition radii 8 of the main bearing journals 6 and one impact device 1 is designed and configured for the impact hardening of the transition radii 8 of the connecting-rod bearing journals.