EP2825340A1

EP2825340A1 - Method and device for the fracture separation of a workpiece

Info

Publication number: EP2825340A1
Application number: EP13710346.1A
Authority: EP
Inventors: Siegfried Gruhler; Helmut Kutz; Horst SCHÖLLHAMMER; Matthias Drinkmann
Original assignee: Mauser Werke Oberndorf Maschinenbau GmbH
Current assignee: Mauser Werke Oberndorf Maschinenbau GmbH
Priority date: 2012-03-12
Filing date: 2013-03-12
Publication date: 2015-01-21
Also published as: DE102012112539A1; WO2013135652A1; CN104271308A; CN104271308B; MX2014010985A; US20150108195A1; KR20140132411A; JP2015516888A

Abstract

A method and a device for the fracture separation of a workpiece and a workpiece fracture-separated by the method according to the invention or with the device according to the invention are disclosed. According to the invention, formed at a distance from a fracture separating notch (16, 18) is at least one fracture directing notch (24), which plays a part in determining the path followed by the fracture separating plane (28). The device for the fracture separation of the workpiece has a laser unit for forming the fracture separating notch (16, 18) and a machining unit for forming the fracture directing notch (24).

Description

Method and device for fracture separation

a workpiece

description

The invention relates to a method for fracture separation of a workpiece according to the preamble of claim 1, a device for fracture separation of a workpiece and a method according to the method or by means of the device

fracture-separated workpiece.

In EP 0 808 228 B2 of the Applicant is a generic

Fracture separation method described in which in a fracture-breaking bearing eye, for example a connecting rod by means of laser energy, a fracture separation plane predetermining notch is formed. This notch consists of a plurality of notch portions, the distance of which results essentially from the pulse rate of the laser and the feed rate of the laser beam with respect to the connecting rod. It was found that the notch impact number can be increased considerably compared to through notches by these notch portions, so that a notch and an optimized fracture separation surface with relatively less

Laser power is possible. Due to the low laser power and the associated low introduced heat energy into the workpiece an undesirable, deep structural change in the notch area is avoided, with certain edge zones of the notch undergo a structural transformation and thus improve the fracture separation behavior.

In the applicant's DE 2005 031 335 A1, an improved method is described in which the notch is not straight but rather sinusoidal with straight end sections. It has surprisingly been found that the fracture separation process can be further improved by such a notch design.

In DE 10 2010 014 085 A1 of the applicant, a method is described in terms of the laser type, the pulse rate, the workpiece material and the laser power is matched to each other, that the distance of the notch portions described above is substantially greater than that distance, which is calculated from the

Feed rate, the relative movement and the pulse rate of the laser results. Such a behavior can be adjusted for example by means of a fiber laser. Such fiber lasers may, in principle, be diode-spotted solid-state lasers, with a core of a glass fiber forming the active medium. The radiation of the solid-state laser is introduced via coupling into the fiber, in which then the actual laser gain takes place. The beam properties and the beam quality of the laser can be adjusted via geometry of the fiber, so that the laser remains largely independent of external influences and shows a very simple structure.

After emerging from the said active fiber, the laser beam is introduced into a glass fiber, via which the radiation is then guided to the actual laser head and is directed by way of focusing optics onto the workpiece to be machined. Such fiber lasers are characterized by a very good electrical-optical efficiency and outstanding beam quality in a very compact structure, so that less costly solutions can be created with a small space than conventional lasers.

The above-described methods and devices are used with great success in fracture separation of a wide variety of steel alloy workpieces.

Particularly in the automotive industry, efforts are being made to use lightweight components to reduce the power-to-weight ratio of vehicles and to reduce fuel consumption. Light metal alloys are also used in engine construction. For example, aluminum and

Titanium connecting rods are used in internal combustion engines.

Since the above-described method for fracture separation of the connecting rod in a bearing shell and a connecting rod side part in engine production due to the well-controlled technology and the relatively low

Has enforced investment costs, this method should also in such Lightweight construction be used. However, it turned out that conventional

Processes are not suitable, for example, aluminum connecting rods fracture with the desired precision, since in preliminary tests showed the fracture separation plane is not in the predetermined range but runs out, so that it to so-called

Kegeltassenbrüchen comes, in which the fracture separation plane towards a

Bolt hole of the connecting rod expires, so that in the Schraublochbereich results in a fracture-separated part of a conical projection and the other fracture-separated part corresponding to a tapered funnel. However, such a cone cup breakage is not acceptable, since the joining behavior of the fracture-separated parts is insufficient. Such a fracture behavior was particularly in forged Aluminiumpleueln, since these usually have a relatively low silicon content. With cast aluminum rods, this undesirable fracture behavior occurs to a lesser extent since the silicon content is higher. A similar problem arises in Titanpleueln.

In contrast, the invention has for its object to provide a method and apparatus for fracture separation of a workpiece and a workpiece, which, even with the use of a lightweight material, such as aluminum or titanium alloys, a fracture toughened material or a fracture behavior in conventional fracture separation negative impact surface treatment ensures improved fracture behavior.

This task is done in terms of the procedure by the

Feature combination of claim 1, in terms of the device by the combination of features of the independent claim 13 and with respect to the workpiece by the feature combination according to the sibling

Claim 10 solved.

Advantageous developments of the invention are the subject of

Dependent claims.

The inventive method is used for fracture separation of a workpiece along a bearing eye, wherein at this diametrically arranged Bruchtrennkerben be formed in a peripheral wall, which give approximately the fracture separation plane. The fracture separation then takes place by means of a Crackdorns, in the

Inserted bearing eye and spread radially to apply a breaking separation force on the bearing eye. According to the invention at least one Bruchleitkerbe is formed at a distance from the fracture separation notches, which also determines the course of the fracture separation plane. This Bruchleitkerbe is inventively designed so that the fracture separation plane is within the predetermined range and thus the emergence of

Kegeltassenbrüchen or the like even with fracture-resistant materials such

Light metal alloys can be avoided.

The Bruchleitkerbe invention provides excellent protection against breakages. These can occur, for example, in a workpiece with a threaded hole. In the case where the threaded hole as

Through hole is formed and the threads are relatively close to the desired fracture separation plane, it may happen that the break in the direction of the thread expires and thus does not have the predetermined course. Due to the associated damage to the thread, the workpiece is unusable. For workpieces with threaded blind hole drilling can be used for thread cutting

so-called withdrawal letters arise. When fracture separation of such

It can then also happen that the fracture separation plane is misdirected by these retraction grooves. All these mistakes can be made by means of

Bruchleitkerbe be avoided.

The fracture separation notch on the outer circumference forms a protection against false leads, in particular in the case of forged workpieces, in which the forged skin is cold-hardened, for example by shot peening. Such Schmiedepleuel with

cold-forged forge are used, for example, in high-performance engines. Without such Bruchtrenn- / Bruchleitkerbe would break the fracture separation plane in the range of work-hardened forged skin of the desired course in such a workpiece (faulty line).

The workpiece according to the invention is produced by such a method. The device in particular for carrying out this method has a Laser unit for forming the fracture separation notches, a cracking unit and a

Processing unit for forming the at least one Bruchleitkerbe, said processing unit is preferably a mechanical processing unit.

The Bruchleitkerbe is machined in one embodiment

educated. Alternatively, the Bruchleitkerbe course be formed in other ways, for example by laser energy or by forming, for example by forging. In this forging process, the workpiece is compressed in the desired area, so that the Bruchleitkerbe arises. The formation of the Bruchleitkerbe can also be electrochemical (Electrochemical Machining). In this case, a tool electrode and the workpiece are in an electrolyte

added. When a voltage is applied then the workpiece becomes local

removed, wherein the Abtraggeometrie depends on the Werkzeugelektrodengeometrie. The voltage can be applied as a DC voltage or pulsed to increase the precision.

The method according to the invention is used in particular for workpieces, for example a threaded bore, which has an opening in the region of the intended fracture separation plane, on the circumference of which the fracture guide notch is then formed.

The fracture separation notches are preferably introduced in the manner described above by laser energy, preferably by means of a fiber laser.

The fracture separation behavior can be further improved if the

Bruchtrennkerben are formed circumferentially on the bearing eye.

For circumferential training either the laser and / or the workpiece can be pivoted about a pivot axis.

In one embodiment, it is preferable to form the fracture separation notch and / or the fracture guide groove, respectively, by a plurality of notch portions that complement each other to the fracture separation notch. In a variant of the invention, the workpiece is a connecting rod, the connecting rod eye is fracture-separated into a bearing shell and a connecting rod side part. In this case, the fracture separation notches are diametrically formed on the peripheral wall of the bearing eye and in each case a Bruchleitkerbe formed in screw holes of the connecting rod. However, the invention is by no means limited to an application in connecting rods, but can also be used in other bruchzutrennenden workpieces in which, for example, a bearing cap to be separated from a block or the like. Such tasks arise, for example, crankshaft housings, camshaft housings, etc.

The fracture behavior can be further improved if the workpiece is thermally treated at least partially in the region of the fracture separation notch and / or the fracture guide groove before the actual fracture separation.

The fracture separation can be carried out in a conventional manner by the so-called impact or crack cracking, wherein an expanding mandrel with a

Bruchtrenn force is applied, which is sufficient to initiate cracking. Alternatively, the so-called fatigue crack cracking or crack propagation cracking may be performed, in which the expanding mandrel has a fracture separation force

superimposed or the fracture separation force upstream alternating dynamic force is applied, so that forms a fatigue crack. This process has advantages, especially with a very fine microstructure. Details of this method are disclosed in DE 10 137 975 A1 of the applicant.

The fracture separation behavior can also be improved by the fact that the fracture separation notches and / or the Bruchleitkerben are not approximately rectilinear but executed with transversely to their longitudinal sections (bulges) executed, so that in a first approximation, a sinusoidal or zig-zag -shaped fracture separation notch geometry forms. As a result, a wave-shaped cracking region forms during the fracture separation, which enables a secure pre-centering of the fracture-separated workpiece parts, for example during subsequent screwing. Such a form laser notch is disclosed for example in DE 10 2005 031 335 A1 of the applicant.

When using an aluminum alloy, this thermal

Treatment by heating the workpiece. This heating can be done for example by means of laser energy and / or a suitable method, for example by induction.

The inventive device can be equipped with a turning table for the

Be formed workpiece, wherein an associated laser itself with a

Swivel axis can be executed.

The cycle times can be reduced if a workpiece with two

Laser units is processed.

As already indicated, the combination of Bruchleit- and fracture separation notch is advantageous for certain materials (light alloys (such as Ti, AL alloys) fracture toughened material, material with work hardened outer skin) and / or used in workpieces in which by the choice of materials,

Surface treatment or by the geometry, for example by the

Fracture separation plane crossing tapped holes there is a risk of misdirection.

A preferred embodiment of the invention will be explained in more detail below with reference to schematic drawings. Show it:

Figure 1 is a three-dimensional representation of a forged

Aluminiumpleuels;

Figure 2 is a partial sectional view of the connecting rod of Figure 1;

3 shows the course of a fracture separation plane after the fracture separation of

Workpiece according to Figure 1; Figure 4 is a schematic diagram of a laser unit of the device according to the invention, are formed with the two fracture separation notches in the connecting rod of Figure 1;

Figure 5 shows a variant of the device according to Figure 4 and

Figures 6 and 7 embodiments of a connecting rod with form laser notches.

The connecting rod 1 of an internal combustion engine shown in Figure 1 consists of an aluminum alloy, which has a comparatively high proportion of silicon, for example between 0.3 to 2 percent by weight and thus, as explained above, difficulties in cracking in the conventional manner, since cone cup fractures may occur.

Similar to Stahlpleueln the aluminum connecting rod 1 has a large connecting rod 2 and a small connecting rod 4, between which a connecting rod 6 extends. By the fracture separation process (cracking) described below, the connecting rod in the region of the large connecting rod 2 in a connecting rod-side part 8 and a bearing shell 10 is to be fracture-separated. After the fracture separation, the two elements are joined again and screwed by means of two screws 12, of which only one is visible in the illustration according to FIG. These screws 12 may be conventional steel screws. Similar to the conventional method, the fracture separation plane is defined by diametrically arranged fracture separation notches in the circumferential wall 14 of the large connecting rod 2. In contrast to the conventional solution, however, these fracture separation notches 16, 18 are formed not only in the region of the peripheral wall 14 but circumferentially, i. these fracture separation notches 16, 18 extend along the circumferential wall 14 and along the adjacent end face 20, the respective side face 22 and the rear end face not visible in FIG. 1, so that the entire circumferential face of the respective connecting rod web is encompassed. Preliminary tests have shown, however, that such a circumferential fracture separation not always sufficient to prevent the formation of

cone-shaped fractures to avoid. Accordingly, according to the invention at a distance from the respective circumferential break separation notch 16, 18 a Bruchleitkerbe 24 is formed. This is shown in the sectional view of Figure 2, a

Vertical section through the left in Figure 1 part of the large connecting rod 2 shows. In this partially sectional view can be seen a screw hole 26 which is penetrated by the screw 12, wherein in Figure 2 in the region of the cut

Bolt hole 26, the screw is omitted. In the plane defined by the circumferential fracture separation notch 18 plane, which is located in the dash-dotted line broken fracture plane 28, the Bruchleitkerbe 24 is formed. This thus forms a circumferential recess in the screw hole 26. This recess is preferably mechanically, for example by a puncture tool and thus by

Circular piercing / turning trained. In this case, the angle at which the cutting edge of the insertion tool is made with respect to the peripheral wall of the screw hole 26 can be about 60 ° to 90 °.

For example, a four-spindle machining unit can be provided for this mechanical machining, which makes it possible to machine several connecting rods and / or both bolt holes at the same time. It is preferred if this mechanical processing unit is designed according to the inverse concept, in which the spindles are arranged stationary, while the workpiece performs the required relative to the machining relative movements to the spindles.

According to the invention, a break guide notch 24 is thus formed at a distance from the fracture separation notch 16, 18 in the region of the intended fracture separation plane 28, so that the emergence of cone cup fractures can be reliably prevented. In the exemplary embodiment according to the invention, the fracture separation notches 16, 18 are introduced by laser energy, for example by the method explained in the introduction to the description, preferably by means of a fiber laser, so that the thermal load and thus the structural transformation in the region of

Break separation score is minimal.

FIG. 3 shows a typical fracture surface course that occurs when the method according to the invention is used. Shown is, for example, the fracture surface in the region of the Pleuelaugenstegs shown in Figure 2 of the bearing shell 10. Man recognizes the screw hole 26 and the bearing cup side part of the

Perimeter of the screw hole 26 formed Bruchleitkerbe 24, which forms a kind of chamfer after the fracture separation. Also visible is the surrounding

Rupture cut notch 18 made by means of a fiber laser. As described above, the fracture separation notch 18 is composed of a plurality of notched portions 30 spaced apart from each other. In the illustrated embodiment, the laser beam is directed at an angle of 30 °, i. obliquely coupled to the peripheral surface. Of course, other Einkoppelwinkel can be realized.

It can be seen in this illustration that the actual fracture separation surface 32 is very flat from the circumferential fracture separation notch 18 to the inside

Bruchleitkerbe 24 runs - a cone cup break is not even begin to determine.

In principle, the formation of the Bruchleitkerbe 24 can also be done by laser energy or otherwise. It is conceivable, for example, the Bruchleitkerbe 24 form by targeted compression of the material in this area, so that the Bruchleitkerbe 24 practically formed by a formed due to the buckling concavity in the screw hole area. Such a compression process is described for example in DE 43 03 592.

The fracture separation process and thus the quality of the fracture separation plane can be further improved if the connecting rod before fracture separation at least partially in

Area of the proposed fracture separation plane 28 is heated. The special feature of some aluminum alloys is used, in which the fracture toughness decreases with increasing temperature. Steel alloys show exactly the opposite behavior, in which the fracture toughness increases with increasing temperature. This heating can be done, for example, inductively. In principle, it is also possible to carry out this heating additionally or alternatively by means of the laser.

Similarly, in other alloys, fracture toughness can be reduced by partial cooling of the respective workpiece

is carried out. The fracture separation of the connecting rod can be carried out by means of a device according to the invention, which may have a plurality of processing units, which are arranged locally separated from each other or else may be integrated into a system. In principle, a laser unit is required for introducing the fracture separation notches 16, 18, a cracking unit for fracture separation and a joining unit for assembling the fracture-separated elements by inserting or tightening the screws 12, which may remain in the connecting rod during fracture separation. Furthermore, a mechanical processing unit is required for forming the Bruchleitkerben 24, wherein this processing unit is preferably not integrated into the actual breakage separation unit, but by a

Inverse machine or the like is formed. In this also an oil hole 33 (see Figure 1) could be formed in the small connecting rod eye.

The actual laser unit according to FIG. 4 has a fiber laser of the type described at the beginning, in the laser head 34 of which focusing optics are arranged so that the laser beam 36 is machined at a predetermined angle

Surface is coupled. This angle is shown at

Embodiment in about 30 °.

The laser head can be rotated about its vertical axis a (see dashed line in Figure 4). Furthermore, the laser head 34 is on a guide

arranged over which it is movable in the x and y direction. The connecting rod, of which only the cut large connecting rod 2 is visible in Figure 4, is in the

illustrated embodiment, arranged on a turning table, which in turn is pivotable about an axis b, wherein the pivot axis perpendicular to

Drawing plane runs. FIG. 4 illustrates by way of example a possibility of a large number of possibilities for forming the circumferential fracture separation notches 16, 18. At the beginning of the machining operation, the laser head 34 is brought into the position "1" shown in FIG. 4 and then moved along the y-axis, so that the section of the fracture separation notch lying in the peripheral surface 14 is formed.

Subsequently, the laser head 34 is moved back to its original position and moved in the x direction in the position marked "2" and the in FIG. 4 formed on the top right circumferential portion of the other break separation notch 16. After this step, the laser head 34 is moved in the position shown in dashed lines and pivoted about the axis a by 180 °, so that in the peripheral surface 14 lying portion of the fracture separation notch 16 is formed ("4"), wherein this in the direction of arrow in FIG 4, the laser head 34 is moved to the left along the x, y guide and, according to "5", the circumferential section of the other break separation notch 18 is formed.

In a subsequent step "6" the connecting rod is rotated about the axis b by 180 ° and then the lying in Figure 4 below, after the rotation of the

Turning table then formed left upper peripheral portion of the fracture separation notch 16 - the fracture separation notch 16 is then completed. After this step "7", the laser head 34 is pivoted back to its original position (step "8") and the remaining surface portion of the fracture separation notch 18 processed, which comes to rest in the above-described pivot position of the turning table in the illustration of Figure 4 right above. This step is indicated by "9" in Fig. 4. That is, by simply pivoting the connecting rod and the laser, the two circumferential fracture separation notches 16, 18 can be formed comparatively quickly.

Figure 5 shows a variant in which the formation of the fracture separation notches 16, 18 can be performed much faster. In this variant, in addition to the one laser with the laser head 34, a further laser unit with a laser head 38 is provided. This can, similar to the embodiment described above, be pivoted about a vertically extending axis a2 and moved in the x ₂ , y ₂ direction. With such an arrangement, it is possible, for example, each two peripheral portions of the respective laser notches 16, 18 form simultaneously. In the relative position of the laser heads 34, 38 in FIG. 5, the region of the fracture separation notch 18 lying on the upper left is thus formed above the laser head 34, while the fracture separation notch 18 is formed on the laser head 34

Laser head 38 forms the area lying in the peripheral surface 14 of the laser notch 18. Of course, this arrangement could also be controlled so the one laser head 34 processes the one fracture separation notch 18 and the other laser head 38 processes the other fracture separation notch 16.

As mentioned, according to the inventive method and with the device according to the invention (laser unit, mechanical processing unit for the Bruchleitkerbe 24) can also be used for machining other workpieces, in which in the fracture separation plane at a distance from the fracture separation notch

Breakthrough or the like is formed, which allows the formation of a Bruchleitkerbe spaced from the fracture separation notch. The workpiece can also be movably mounted along an x, y guide.

The setting behavior of the fracture surfaces can be further improved by a partial laser irradiation.

The fracture separation can be carried out in a conventional manner by the so-called impact or crack cracking, in which the over the expanding mandrel

applied fracture separation force is increased until the crack occurs. As explained at the outset, it is particularly advantageous in the case of very fine structures when the fatigue crack cracking described in DE 10 137 975 A1 is used, in which the expanding mandrel is acted upon by an oscillating device with an alternating force overlying the fracture separation force or upstream of it that the fracture separation region of the workpiece is set in vibration, which then lead to the formation of a fatigue crack.

In fracture cutting of connecting rods or similar workpieces, the fracture-separated parts are screwed together after the fracture separation. This

Screwing can be significantly simplified if the fracture separation notch is wave-shaped or zig-zag-shaped, so that transverse to Bruchtrennkerbenlängsachse offset sections arise. This sine wave or waveform then runs in the

Fracture separation plane away from the fracture separation notch more or less flat and allows pre-centering of fracture-separated parts. The fine centering then takes place through the irregularities in the structure predetermined by the microstructure

Cracking plane. 6, the fracture separation notches are not rectilinear and circumferential as in the exemplary embodiment according to FIG 1, but have a wave-shaped structure which is designed to run around the circumference chosen light sinusoidal shape, being in each

Wall area (Innenumfangswandung, end face areas and

Outer circumferential wall) is formed in each case a downwardly or upwardly deflected "shaft" 40. According to the invention, it is preferred that these shafts 40 terminate in straight sections 42 which lie, to a first approximation, in the fracture separation plane which would be formed with a straight fracture separation notch geometry Accordingly, the fracture separation notches in the corner regions, ie, in the transition regions from the peripheral wall or the outer circumferential wall to the end wall regions, can then also be formed in a straight line

outer side surfaces / outer peripheral surfaces approximately parallel to the bearing axis. In principle, it is sufficient if in each surface section of the circulating

Fracture separation notch 14, 16 is only one in the illustration of Figure 6 up or down extending buckle (shaft 42) is formed.

FIG. 7 shows an embodiment in which the shaping laser notch with its wave form or the bulges extending upwards and / or downwards is formed only in the area of the inner circumferential surface 14. The areas of

Fracture separation notch on the two end faces 20 and on the outer

Side surfaces 22 are formed in a straight line according to the embodiment in Figure 1.

As mentioned, instead of the described may be approximately sinusoidal

Buckling 40 also other notch geometries are used.

Disclosed are a method and an apparatus for fracture separation of a workpiece and a workpiece which is fracture-separated by the method according to the invention or with the device according to the invention. According to the invention is in Distance to a break separation notch at least one Bruchleitkerbe formed, which determines the course of the fracture separation plane with. The device for fracture separation of the workpiece has a laser unit for forming the fracture separation groove and a machining unit for forming the fracture guide groove.

LIST OF REFERENCE NUMBERS

1 connecting rod

2 large connecting rod eye 4 small connecting rod eye 6 connecting rod

8 connecting rod side part

10 bearing shell

12 screw

14 peripheral surface

16 fracture separation score

18 fracture separation score

20 face

22 side surface

24 break guide notch

26 screw hole

28 fracture separation plane

30 notch section

32 fracture surface

33 oil hole

34 laser head

36 laser beam

38 laser head

40 wave

42 straight section

Claims

claims

1. A method for fracture separation of a workpiece along a bearing eye, wherein diametrically arranged to each other break separation notches (16, 18) in one

Peripheral wall (14) are formed, which give approximately the fracture separation plane (28), wherein a cracking mandrel is used to apply a fracture separation force to the bearing, characterized in that at a distance from the fracture separation notches (16, 18) at least one Bruchleitkerbe (24 ) is formed, which lies in the fracture separation plane.

2. The method according to claim 1, wherein the Bruchleitkerbe (24) is formed by machining or electrochemical or by forming.

3. The method according to claim 1 or 2, wherein the workpiece in the region of the fracture separation plane (28) has at least one breakthrough at the

Peripheral wall, the Bruchleitkerbe (24) is formed.

4. The method according to any one of the preceding claims, wherein the fracture separation notch (16, 18) is formed with laser energy, preferably by means of a fiber laser.

5. The method according to any one of the preceding claims, wherein the fracture separation notches (16, 18) are formed circumferentially.

6. The method according to claim 5, wherein a laser unit or the workpiece with respect to the other element is rotatably arranged.

7. The method according to any one of the preceding claims, wherein the workpiece is partially heated or cooled before the fracture separation in the fracture separation plane region.

8. The method according to any one of the preceding claims, wherein the separating takes place by forming a fatigue crack.

9. The method according to any one of the preceding claims, wherein the fracture separation notch and / or the Bruchleitkerbe is formed with approximately wave or zigzag-shaped sections.

10. workpiece, produced by a method according to one of

Claims 1 to 9 and preferably consisting of a fracture-resistant material, preferably an aluminum alloy or a titanium alloy and / or with a work hardened or otherwise pretreated surface.

11. Workpiece according to claim 10, wherein this is a connecting rod (1) whose large connecting rod eye (2) in a bearing shell (10) and a

Breaking split notches (16, 18) and in screw holes (26) in each case a Bruchleitkerbe (24) is formed on a peripheral wall (14) diametrically to each other on the connecting rod side part (8).

12. workpiece according to claim 1 1, wherein the fracture separation notch (16, 18) is formed circumferentially.

13. A device for fracture separation of a workpiece, comprising a laser unit for forming a fracture separation notch and a mechanical processing unit for forming a Bruchleitkerbe.

14. The device according to claim 13, wherein the workpiece is arranged on a turning table and a laser head (34, 38) with respect to the workpiece and / or the latter with respect to the laser head (34, 38) is rotatable and / or movable.

15. Device according to claim 13 or 14, with a

Oscillating device for applying the expanding mandrel during the

Fracture separation process with an alternating dynamic force.

16. Device according to one of the claims 13 to 15, comprising a unit for heating or cooling the fracture separation plane region.