KR20130055592A - Method for fracture splitting workpieces, workpiece and laser unit - Google Patents

Abstract

The present invention relates to a method of breaking apart a workpiece (1) and to a workpiece made by such a method. According to the invention, for example, the type of laser, pulse rate, pulse duration, material of the workpiece and / or laser power may be calculated by calculation of the feed rate V of the laser beam 12 and / or the workpiece 1 and It is selected such that the distance of the notch portion 6 is considerably larger than the notch distance K obtained from the pulse rate of the laser. The feed adjustment also allows the formation of an inclined laser notch for the curved surface, such as in the case of a ball or roller guide. According to the invention, the feed rate is adjusted and / or periodically according to the geometry of the workpiece during laser processing.

Description

METHOD FOR FRACTURE SPLITTING WORKPIECES, WORKPIECE AND LASER UNIT}

The present invention relates to a method of breaking and dividing a workpiece according to the preamble of claim 1, the workpiece and the laser unit produced according to this method.

Applicant's EP 0 808 228 B2 describes a general fracture splitting method, in which a notch predefining a fracture surface is formed at the upper end of the connecting rod to be fractured with laser energy. This notch consists of a number of notches, the distance of which is determined substantially by the pulse rate of the laser and the feed rate of the laser beam relative to the upper end of the connecting rod. These notches have been found to significantly increase the stress concentration coefficient compared to continuous notches, and thus can form notches with relatively low laser power. This low laser power and accompanying low thermal energy prevents undesirable deep structural changes in the notched region, which are only given to the special edge region of the notch, thus improving fracture splitting behavior.

Applicant's DE 2005 031 335 A1 describes an improved method, in which the notch has a sine shape with no straight shape, but with an extended end. Surprisingly, it has been found that the fracture splitting behavior can be further improved with this notch design.

As a disadvantage of the method described above, as described, the feed rate and the pulse rate must be adjusted to form a notch that improves the notch behavior. In addition, particularly when forming a connecting rod top end or sinusoidal notch having a large axial length, the laser beam must be refocused because the depth of focus is not sufficient to form the notch (perforation) with the required precision.

On the other hand, it is an object of the present invention to provide a method capable of making a notch of a fracture split notch with little effort. It is also an object of the present invention to provide a workpiece produced according to this method and a laser unit for carrying out such a method.

The object is achieved with a method comprising the features of claim 1, a workpiece comprising the features of independent claim 12 and a laser unit comprising the features of claim 14.

In the method according to the invention, similar to the conventional method, the laser notch is formed of laser energy, and the notch has a plurality of notches. According to the present invention, the type of laser, pulse rate, pulse duration, material of the workpiece, and laser output have a notch distance greater than the notch distance calculated from the feed rate, relative motion, and pulse rate (frequency) of the laser by calculation. Adjusted to be significantly larger.

The oscillation of the laser beam is preferably made inclined with respect to the longitudinal notch axis.

Surprisingly, with the appropriate selection of the above criteria, it has been shown that notches provided with perforations can still be made in the case of very high pulse rates and fast feeds, the notch distances being significantly larger than the calculated notch distances. With the advantage of this method, high frequency lasers can be used with very high feed rates, so that laser notches can be formed much faster and with lower heat introduction than with conventional solutions.

In a particularly preferred case of the invention, the feed rate during laser processing is varied such that a notch having notches of different depths is formed. The "depth" of the notch means the depth of penetration in the direction of the laser beam. Moreover, the depth of the continuous area (hereinafter referred to as the notch base) can be changed by changing the feed speed. This notch has a more improved stress concentration coefficient and thus represents an improved fracture mechanics mechanism.

According to the invention, it is preferred that the feed rate is varied according to the periodic function, for example the sine function or the geometry of the element.

The feed rate during laser processing can vary in the range of 100 mm / min to 1500 mm / min.

Legal claim 1 claims that the processing parameters and the type of laser are chosen such that the notch distance is greater than the calculated notch distance. The Applicant retains its right to seek other independent claims, for example, within the scope of the divisional application where changes in feed rate during laser processing are independently claimed for processing parameters and types of lasers. In other words, such an independent claim would then relate to laser machining the breaking split notch at variable feed rates (characteristic of claim 3 without reciting claim 1).

In such a case, the laser beam may move in kinematic reversal with respect to the idle workpiece, but the workpiece may move with respect to the idle laser, with a mixed form being advantageous. The laser beam may be oscillated in the radial direction, ie perpendicular to the fracture split notch or inclined relative to the fracture split notch.

In the case of radial oscillation, the notch is thus perpendicular to the notch axis, and in the case of oblique oscillation the notch is tilted relative to the notch axis. The oscillation is preferably carried out at an angle of ≦ 45 ° with respect to the plane perpendicular to the longitudinal notch axis (in the case of the connecting rod, this is the radial plane of the top of the connecting rod). In the horizontally supported connecting rod and in the direction of transport (notch axis) perpendicular thereto, the angle will then be 30 ° with respect to the horizontal and 60 ° with respect to the vertical (see FIG. 11).

In the case of the present invention, the actual notch distance resulting from the selected parameter is more than 10 times the calculated notch distance obtained from the pulse rate and the feed rate.

With the right choice, even a notch distance 50 times larger can be achieved.

According to the present invention, it is preferable to use a so-called fiber laser as the laser. Such fiber lasers are known in the art and thus no description of their structure will be needed.

In the case of the present invention, a laser having an average power of 50 W or less and a pulse rate of 1 kHz or more, preferably 10 kHz or more is used, and the transfer may be 1000 mm / min or more. On the other hand, the pulse rates in the conventional method are in almost the same magnitude range and the pulse frequency is certainly longer, for example 50 to 140 Hz.

In a preferred embodiment of the invention, the notch extends from the continuous notch base.

The workpiece produced according to the method may be, for example, a connecting rod or crankcase or other workpiece in which bearing holes or other areas are divided by a fracture splitting method.

Workpieces made according to the method may have notches of different depths by varying the feed rate of the laser. It is particularly preferred that the change is repeated periodically along the notch.

The laser unit for carrying out the method comprises a laser module, a laser head for concentrating a laser beam from the laser module on the workpiece to be machined and a transport axis acting in the conveying direction. The latter is controllable via the control unit such that the feed during laser processing changes periodically.

In this connection, a very dynamic feed axis is preferred, which makes it possible to change the feed speed with an acceleration in the range of at least 0.5 g, preferably in the range of 1 to 2 g. In other words, the feed rate profile can be sinusoidal with high precision and even in a limited case even nearly square.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the schematic drawings.

1 shows a schematic diagram of a laser unit for making a fracture split notch at the top of a large connecting rod.
2 is a greatly enlarged fracture split notch made according to the method according to the invention.
3 shows the correspondence when the laser power and / or pulse rate is changed.
4 shows the breaking split notch along the transfer.
5 shows the fracture split notch according to the average laser power.
6 shows a diagram to emphasize the dependence of the notch depth on the transport of the laser beam.
7 shows a diagram for highlighting the feed rate adjustment as a function of time.
8 shows a diagram for emphasizing that the notch depth is adjusted according to the average feed speed by the feed speed adjustment.
9 shows a photograph of a fracture split notch under comparable conditions with and without feedrate adjustment.
10 schematically shows a laser unit that can be used in a laser method with a feed rate adjustment.
11 shows a schematic diagram of the laser head of the laser unit according to FIG. 10.

1 shows a cross-sectional view of a large connecting rod upper end 1, which is separated into a bearing seat and a member on the connecting rod side by fracture splitting. The course of this breaking dividing surface 2 is predetermined by two breaking dividing notches 4 (only one shown in FIG. 1) opposite to each other, and this notch preferably has a plurality of notches 6. It is in the form of perforation. As described above in connection with the prior art, after forming the breaking split notch 4 in the left and right walls of the connecting rod upper end 1 in FIG. 1, an expansion mandrel is inserted into the connecting rod upper end and then the expansion. By properly extending the mandrel and supporting the connecting rod top end, the bearing seat is separated from the rod side part of the connecting rod, which, due to the structural conditions, makes it possible to fit the two members correctly by the geometry of the fracture splitting surface created. Easier

According to the invention, a fiber laser is used to design the fracture split notch 4, the laser head 8 of which is schematically shown in FIG. 1. This kind of fiber laser can basically be a diode excited solid state laser, the core of the glass fiber making up the working medium. The radiation from the solid laser is introduced into the fiber via oscillation, where actual laser amplification takes place. The laser's beam characteristics and beam quality can be controlled through the geometry of the fiber (glass fiber) so that the laser remains largely independent of external influences and has a very simple structure.

After exiting the working fiber, a laser beam is introduced into the glass fiber, through which the radiation is directed to the laser head 8 shown in FIG. 1 and through the focusing optics 10 the workpiece to be processed (1). Is focused on). In the embodiment shown, the laser beam 12 impinges radially, ie perpendicularly to the notch axis (vertical direction in FIG. 1). In this arrangement, the 90 ° oscillation has the disadvantage that the focusing optics 10 can be soiled with molten material because reflections and possible residual molten mules are returned directly along the optical path. If the oscillation is made inclined, for example at 30 ° or 45 °, the possible reflections and residual melt will leave at the reflection angle (see FIG. 1: 12 ""), thus no fouling occurs. The tilt oscillation laser unit will be described with reference to FIGS. 10 and 11.

Another disadvantage of 90 ° oscillation is that weak or strong beam control is not possible. When inclined, the geometry of the notch can be further influenced by weak (upward in FIG. 11) or strong (downward in FIG. 11) beam control. The geometry of the notch can be further influenced by the air flow acting on the melt passing through the nozzle. The dependent claims may relate to the two points mentioned above.

These fiber lasers have excellent beam quality with excellent electro-optic efficiency and large focus depth and a very compact structure, and thus a small construction space can provide a more cost effective solution than conventional lasers. The high peak capacity and large concentration capability of the fiber laser results in a relatively high power density, so that the evaporated portion of the material predominantly exists. However, part of the energy is converted to heat, nevertheless there is still a thermal impact of the melt and the environment. Residual heat can accumulate, resulting in a separate melting phenomenon, by which the calculated notch distance is clearly smaller than the actual notch distance and also changes other parameters, but this notch distance is also relatively stable.

After machining the connecting rod wall on the left side of FIG. 1, the laser head is rotated about 180 ° and the right connecting rod wall is machined. In principle a cross head can also be used, in which case both walls can be machined simultaneously.

In the embodiment described above, the workpiece, ie the connecting rod, is fixedly clamped, the laser head 8 is moved at a feed rate V in the axial direction or parallel to the axis, the laser power is about 50 W, In the embodiment shown, the pulse frequency of the laser is approximately 20 kHz. The spot diameter is approximately 30 μm and the feed rate V is about 1500 mm / min. For this parameter, the calculated notch distance would be about 0.00125 mm. In fact, the notch distance K (in this case the laser beam oscillates obliquely at 45 °) is about 0.1 mm.

Fig. 2 is a large enlargement of the connecting rod upper end specifically processed according to the method of the present invention including the above-mentioned parameters, in which the laser beam is oscillated obliquely (45 °). The average laser power is about 50 W and the pulse power is about 8 kW. The perforation distance (notch distance) K is about 0.1 mm, and a continuous notch base G is obtained in which the individual notches 6 which form a perforation are extended. In the embodiment according to FIG. 2, the depth of the notch base G is about 0.51 mm and the depth P (as seen from the radial direction) of the notch part 6 is about 0.78 mm (connecting rod upper end 1). Measured from the circumferential wall of

FIG. 3 shows a similar embodiment with a reduced laser power 40 W and a steeper oscillation (30 °) of the laser beam 12, with no substantial change in the notch distance K, and with this steeper oscillation and In the case of the reduced laser power 40 W, the depth G of the notch base and the depth P of the notch are slightly larger. In the case of a rather steep oscillation, a notch that improves the fracture behavior can thus be formed with even smaller output than in the above-described embodiment.

Fig. 4 shows the dependence of the breaking split notch on the set feed rate V (see Fig. 1) when the laser beam moves in the longitudinal notch direction.

As can be seen clearly, the notch distance hardly changes at other feed rates (500 mm / min, 1000 mm / min, 1500 mm / min). Obviously, however, at lower feed rates, the depth G of the notch base on the one hand is larger and the axial length PG of the notch portion is inversely proportional to the feed, where the difference of 500 mm / min and 1000 mm / min Relatively small

5 shows the dependence of the fracture split notch on the laser output. As shown at the top of FIG. 5, the average laser power was set to 50 W. FIG. The fracture split notch shown below was obtained at an average laser power of 100 W, with the other parameters unchanged. As can be clearly seen, when the laser power is reduced, a rather fine notch structure with a longer notch is formed, but as already mentioned above, the notch distance hardly changes. Moreover, reducing the laser power results in a continuous notch base having a somewhat smaller depth G than in the case of a larger laser power, as expected. In terms of fracture mechanics, it is optimal to use a laser with a relatively small laser power (50 W or less) at an average feed rate in the range of 500-1500 mm / min.

Beam quality can be improved with so-called Q-switches. These Q-switches are optical elements, in the case of pulsed lasers, the pulses are delayed by the switch, the pulse duration is reduced and the pulse height (peak performance) is increased, so a very sharp laser pulse is obtained. This laser pulse increases rapidly and again decreases rapidly when the maximum sharpness is reached. Without this Q-switch, the pulses are obviously wider and flatter.

6 shows the dependence of the notch depth on the feed rate which varies from 100 to 3000 mm / min. In this regard, the size S2 corresponds to the defined measurement G (depth of the notch base) and the size S1 corresponds to the total depth P of the notch (see FIGS. 2 and 3), and thus The length of the notch portion corresponds to the difference GP. The upper curve shows the trend of the total depth S1 of the notch, and the lower curve shows the trend of the depth S2 of the notch base. As is apparent, a relatively strong dependence of the notch depths S1 and S2 appears at relatively low feed rates in the range up to about 800 mm / min. At higher feed rates (approximately 800 to 3000 mm / min), the dependence appears even smaller. These experiments were performed at a pulse frequency of 50 kHz and an average pulse output of 50 W. In this way, the dependence of the geometry of the notch on the feed rate as shown in the above figures was confirmed by the experiment shown in FIG.

As will be explained in more detail later, notch quality was insufficient due to thermal overheating in the notch base region at very low feed rates (<200 mm / min). A black burnt area was created, which made the laser processed workpiece practically useless. The blackened area is shown at the top of FIG. 9, for example, which will be explained in more detail below.

Therefore, in laser processing, care must be taken to control the feed rate so that such qualitative losses do not occur when forming the fracture split notch.

It has been found that varying the feed rate during laser processing avoids this phenomenon, on the one hand creating a fracture split notch which has a sufficient notch depth and on the other hand can be formed at a high feed rate so in a short time, At this point, no qualitative loss is impeded by disruptive mechanical mechanisms.

7 shows an example of the feed rate adjustment, which is performed according to a sine function. Of course, the feed rate adjustment can also be carried out according to another function, preferably a periodic function. The transition of the feed rate within a particular feed range that does not correspond to the total length of the breaking split notch to be formed is shown as a function of time. In this case, a conveying range of 67.5 to 69.5 mm is specifically shown, i.e. only two 2 mm total breaking split notches are shown, but the feed rate adjustment in the region (not shown) of the breaking split notch is performed correspondingly. . A slightly wavy curve from the upper left to the lower right (the upper curve is shown as a break line and the lower curve is shown as a continuous line) shows the actual feed in the direction of the fracture split notch as a function of time (t). It is represented as. During this somewhat wavy transfer, the feed rate changes with the inserted sine function, with a higher amplitude sine function assigned to the dashed laser path, and a smaller amplitude sine function for the continuous line laser motion path. Is assigned to. It can be seen that the feed speed varies at a relatively high frequency, and therefore, the laser head 8 must be greatly accelerated and decelerated in a short time in order to adjust the profile of the movement along the fracture split notch to be formed.

In the diagram according to FIG. 7, the actual values of the feed rates which are respectively adjusted are shown on the right. Therefore, in the upper feed rate adjustment, the feed rate was changed within the range of 117 to 1157 mm / min. When forming the breaking split notch in such a feed rate adjustment, the geometry of the breaking split notch as illustrated in FIGS. 8 and 9 is obtained. 8 shows a plot in which the notch depth generated is adjusted as a function of the mean feed V _m , i. As can be seen in FIG. 8, for example an average feedrate of 800 mm / min (actually the feedrate will vary according to the sine function according to FIG. 7) a fracture split notch with a transition inserted in FIG. 8 is created. . As is apparent, different notches are formed from the notch base having a size S2 (G) corresponding to the sine period. The notch portion indicated by S3 is formed in a region where the feed speed is relatively low. The notch marked S1 is formed in the region where the laser moves at a relatively high speed.

  The trend of the characteristic parameters S1 (P), S2 (G) and S3 (P) according to the average feed is shown in the diagram according to FIG. 8. The upper curve shows the trend of the total notch depth S3 at low feedrate, and the curve S1 shows the change of the notch depth at relatively high feedrate (during constant speed adjustment) and the curve S2 is the depth of the notch base. It shows the trend of. Increasing the average feed rate decreased the notch depth. However, as can be clearly seen, notches having variable notch depths can be formed at each speed adjustment. These notches significantly improved the fracture mechanics compared to the notches mentioned earlier. In other words, by the feed rate adjustment, a relatively deep and sharp initial notch can be formed which certainly improves the initial fracture toughness and the arresting fracture toughness compared to the fracture split notch with continuous perforation without the feedrate adjustment.

Thus, even complex elements can be cracked, wherein the adjustment of the feed rate can be carried out according to the geometry of the element. That is, for very complex elements, including breakthrough, for example in the region of the fracture split notch, the feed rate can be adapted to the geometry of the element, and thus in relatively uncomplicated areas a relatively high Feed rates or amplitudes are applied, and in more critical areas the feed rate adjustment is appropriately reduced to adjust to a lower average feed rate or to a constant feed rate.

The advantages of the above-described feed rate adjustment are highlighted in FIG. 9. The upper part shows a fracture split notch which is controlled at a relatively low constant feed rate of 200 mm / min. The relatively large notch depth and burned / black burnt areas can be clearly seen which may be caused by high heat introduction at low feed rates. Such a fracture split notch is practically useless.

On the other hand, the lower picture shows a notch obtained by adjusting the feed rate according to the method of the present invention, which was adjusted in the range of 117-1157 mm / min. As can be seen clearly, this adjustment reliably avoids combustion in the notch base region. It is also possible to see notches with larger or smaller depths formed with proper feedrate adjustment, which depth also depends on the tilt angle of the laser. In the embodiment shown, the tilt angle, ie oscillation angle, was about 30 ° with respect to the horizontal in FIG. 9.

With reference to FIGS. 10 and 11, a laser unit that is particularly well suited for carrying out the method described above including the feed rate adjustment will be described. According to FIG. 10, the laser unit comprises a laser module 16, which for example comprises a fiber laser and a control unit of the fiber laser. The control unit 16 of the laser unit is configured such that the feed rate of the laser beam can be adjusted in the manner described above.

The laser beam 12 generated by the laser module 16 is directed through a light transmitter 18 to a re-collimator 20, which is simply shown in FIG. 10. In the recollimator the laser beam is converted into parallel beams and the beam diameter is in the range of approximately 6 mm. The parallel beam is then guided through the light transmitter 18 to the laser head 8 and then the laser beam passes through the laser head to the workpiece to be machined (in this case the connecting rod upper end 1). Focus on)). The focused laser beam oscillates at an angle of 30 ° to the horizontal in FIG. 10. The laser head 8 has a Z feed axis 22 through which the feed on the longitudinal notch axis is carried out. The feed axis is a very dynamic axis, by which an extremely high acceleration can be obtained with a high closed loop gain and a large jerk, thus requiring very precise control of the adjustment. The acceleration may be in the range of 1-2 g, for example, the closed loop gain may be in the range of 10 n / min / mm (166.71 / s) and the jerk may be at least 400 m / s ³ . When machining both ends of the connecting rod upper end 1, the laser head 8 has a further pivot axis 24, which pivots the laser head 8 around the Z feed axis 22. . The laser unit also includes an X control axis 26, which allows the entire laser head 8 to move in the X direction (radially relative to the connecting rod upper end 1). By this means a sinusoidal fracture split notch can also be formed.

11 shows the basic structure of guiding a beam in the laser head 8. This figure shows a light transmitter 18 that is connected to a fiber laser (laser module 16). In the collimator 20 the laser beam is converted into a parallel beam having a diameter of approximately 6 mm and then diverted by 90 ° in the direction of the connecting rod upper end axis by the turning mirror 28. The redirected laser beam 12 is then concentrated on the connecting rod top wall, for example via an optical system with a focal length of 100 mm. The orientation of the circumferential wall of the connecting rod is carried out via another turning mirror 32, which in the embodiment shown shows that the laser beam is circumferentially obtained so that an oscillation angle of 30 ° with respect to the horizontal is obtained. It is inclined at an angle of 60 ° to the horizontal to impinge on the wall or at an inclination angle of 60 ° to the vertical part of the laser beam 12 impinging on the diverting mirror 32 (60 ° deflection). The laser beam exits through the nozzle 34 and is focused so that the laser point is about 3 mm ahead of the exit face of the nozzle 34. In order to avoid soiling the optical system 30 and the mirrors 28, 32, a protective glass 34 is provided in the optical path between the nozzle 34 and the turning mirror 32. Also shown in FIG. 11 is the pivot axis 24 where the laser head 8 is pivoted by a pivot bearing 38 and by a motor (not shown) to reach virtually all circumferential wall areas of the connecting rod. It can be pivoted around the Z feed axis 22.

When using fiber lasers and properly selecting feed rate control and relatively high pulse rates (compared to conventional solutions), optimal stress concentrations with substantially lower energy inputs and significantly faster feed rates than with conventional systems Perforations with coefficients can be formed.

The experiment carried out showed that the splitting notch 4 having a distance within the range of 1/10 mm, preferably 0.1 to 0.3 mm, for a fiber laser having a power of 50 W, for example at a pulse frequency of 20 kHz. ) Can be formed. It has been shown that even when a laser having a power of only 30 W is used, a perforated fracture breaking notch 4 can be formed which is very effective.

Disclosed are a method of breaking apart a workpiece and a workpiece produced by the method. According to the invention, for example, the type of laser, pulse rate, pulse duration, material of the workpiece and / or laser output, the distance of the notch is determined by the notch distance (calculation of the feed rate of the laser beam and / or the workpiece and the pulse of the laser). Obtained from the rate). The aforementioned feed rate adjustment can also form a ramped laser notch for a raceway, such as in a ball or roller guide.

According to the invention, the feed rate is adjusted and / or periodically according to the geometry of the workpiece during laser processing.

1 Connecting rod top
2 planes of destruction
4 breaking split notch
6 notch
8 laser heads
10 focusing optics
12 laser beam
14 circumferential wall
16 laser module
18 light transmitter
20 recall
22 feed axis
24 pivot axis
26 control axis
28 turn mirror
30 optical apparatus
32 turn mirror
34 nozzles
36 protective glass
38 pivot bearing

Claims (15)

A method of breaking and dividing a workpiece (1) by laser energy, wherein a fracture dividing notch (4) defining a fracture dividing surface in advance is formed by a relative displacement between the laser beam (12) and the workpiece (1), and In the above method, in which the fracture split notch is in the form of a perforation comprising a notch 6,
Processing parameters, such as the type of laser, pulse rate, pulse duration, material of the workpiece and laser power, are calculated by calculation the feed rate V of the laser beam 12 and / or the workpiece 1 and the pulse rate of the laser. And the distance of the notch portion 6 is significantly greater than the notch distance K obtained from the method. The method of claim 1,
The laser beam 12 is oscillated obliquely with respect to the longitudinal notch axis. 3. The method according to claim 1 or 2,
The feed rate (V) varies during processing. The method of claim 3, wherein
The feed rate V varies according to a periodic function, for example a sine function. The method according to claim 3 or 4,
Feed speed varies from 100 mm / min to 1500 mm / min. 6. The method according to any one of claims 1 to 5,
The actual notch distances (K) are each 10 times larger than the calculated notch distances. The method according to claim 6,
Notch distance (K) is more than 50 times greater than the calculated notch distance. The method according to any one of claims 1 to 7,
The laser used is a fiber laser. The method according to any one of claims 1 to 8,
At a pulse rate of at least 1 kHz, preferably at least 10 kHz, the laser having an average power of 50 W or less. 10. The method according to any one of claims 1 to 9,
The oscillation angle is approximately 30 °. 11. The method according to any one of claims 1 to 10,
Fracture split notch (4) has a continuous notch base with notch (6) extending. Workpiece, in particular connecting rod or crankcase, produced by the method according to claim 1. 13. The method of claim 12,
A workpiece having one or more notches 6 having a small depth and one or more notches 6 having a greater depth being formed approximately repetitively or with another notch depth P depending on the geometry of the workpiece. A laser unit for carrying out the method according to any one of claims 1 to 11,
laser,
A laser head 8 for concentrating the laser beam 12 on the workpiece to be machined, the laser head 8 comprising at least one feed axis 22 acting in the feed direction, and
A laser unit comprising a control unit 16 for changing the feed rate during laser processing. 15. The method of claim 14,
The conveying axis 22 is a laser unit which enables the change of the conveying speed to be> 0.5 g, preferably at most 2 g.

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