KR101609657B1 - Method for fracture splitting workpieces, workpiece, and laser unit - Google Patents

Abstract

Disclosed is a method for fracturing and splitting a work, and a workpiece produced by such a method. According to the invention, the feed rate and / or the laser pulse are adjusted according to the geometry of the workpiece and / or periodically during laser machining.

Description

METHOD FOR FRACTURE SPLITTING WORKPIECES, WORKPIECE, AND LASER UNIT FIELD OF THE INVENTION [0001]

The present invention relates to a method for fracture-splitting a workpiece according to the preamble of claim 1, to a workpiece made according to such a method, and to a laser unit.

The 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 broken down by laser energy. The notch is made up of a plurality of notches, the distance of the notch being substantially determined by the pulse rate of the laser and the feed rate of the laser beam to the upper end of the connecting rod. It has been found by these notches that the stress concentration factor is significantly increased compared to a continuous notch, and thus a notch can be formed with a relatively small laser power. These small laser powers and the accompanying low thermal energy prevent undesirable deep structural changes in the notch area, structural changes are only given to the special edge regions of the notch and thus break down splitting behavior is improved.

The Applicant's DE 2005 031 335 A1 describes an improved method in which the notch does not have a straight shape but has a sine shape with an end extending straight. Surprisingly, it has been found that fracture split behavior can be further improved with this notch design.

As a result of the prior art, a laser notch comprising such a notch is formed, in particular for fracture splitting of the connecting rod and the crankcase, since the fracture behavior of such a notch is superior to the continuous notch. Despite these positive fracture splitting characteristics, there is an effort to further improve the fracture splitting behavior.

It is an object of the present invention to provide a method by which the notch of the fracture split notch can be made with little effort. It is also an object of the present invention to provide a workpiece produced by such a method and a laser unit for carrying out such a method.

This object is achieved with a laser unit comprising a method comprising the features of claim 1, a workpiece comprising the features of independent claim 10 and a feature of claim 12.

In the method according to the present invention, similar to the conventional method, the laser notch is formed by laser energy, and the notch has a plurality of notches. According to the present invention, during laser notch machining, i.e. during notch formation, the relative movement between the laser beam and the workpiece and / or the adjustment of the laser pulse is effected, in effect, being carried out. By this adjustment, notches having notches or notch distances of different depths can be formed. The "depth" of the notch portion means the penetration depth in the direction of the laser beam. Furthermore, the depth of the continuous region (hereinafter referred to as the notch base) can be changed by changing the feed rate and / or the pulse parameter. Such notches exhibit improved stress concentration factors and improved fracture mechanics compared to conventional notches having a rather constant geometry. This method can be practically realized with all kinds of lasers used in fracture splitting.

The oscillation of the laser beam is preferably made oblique to the longitudinal notch axis.

Surprisingly, it has been shown that by properly selecting the above criteria, the notches provided with perforations can still be made in the case of very high pulse rates and fast traverses, the notch distances being significantly larger than the calculated notch distances. The advantage of this method is that a high frequency laser can be used with a very high feed rate, so that the laser notch can be formed with much lower heat input and much faster than the conventional solution.

According to the present invention, it is preferable that the conveying speed varies depending on the periodic function, for example, the sine function or the geometrical shape of the element.

The feed rate during laser machining can vary between 100 mm / min and 1500 mm / min.

For example, the laser beam can move relative to the idle workpiece, either by moving the laser head or using a tilting mirror (scanner) in a substantially simple manner, and, conversely, as the workpiece moves against the idler laser And mixed forms are also advantageous. The laser beam can oscillate radially, i.e. perpendicular to the fracture split notch or at an angle to its fracture split notch.

In the case of radial oscillation, the notch portion is thus perpendicular to the notch axis, and in the case of a tilted oscillation, the notch portion is tilted relative to the notch axis. The oscillation is preferably carried out at an angle of? 45 with respect to a plane perpendicular to the longitudinal notch axis (in the case of a connecting rod this is the radius echo plane of the connecting rod upper end). In the connecting rod supporting horizontally and in the transport direction perpendicular thereto (notch axis), the angle will then be 30 [deg.] With respect to the horizontal and 60 [deg.] With respect to the vertical.

Pulse modulation may be performed by varying the pulse width, the pulse frequency, the pulse amplitude, and / or the pulse phase. In order to vary the recorded pulse power / pulse energy or pulse sequence, for example at a constant pulse power, thus varying the notch depth or notch distance along the course of the notch and thus further optimizing the fracture behavior, Lt; / RTI > for pulse adjustment. For example, in the viscous material, perimeter fracture split notches are formed in which the notch distance or notch depth is such that, for example, the notch distance or notch depth can be varied in the course of the fracture split notch along the portion at the upper end of the connecting rod, Can change.

The parameters can be selected appropriately to perform adjustment, for example, with time controlled pulse energy ramping, wherein the pulse frequency remains substantially constant. In general, "ramping" means a method in which the pulse power increases / increases or begins to decrease during the pulse sequence toward the ramp.

Alternatively, the adjustment may be performed with a pulse sequence / pulse frequency adjustment, in which case the pulse power can be kept approximately constant.

As already mentioned, other parameters can also be changed.

It is also conceivable to adjust both the feed rate and the pulse, which is carried out continuously or in a superposition or simultaneously.

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 therefore no description of their structure is required.

In the case of the present invention, a laser having an average power of 50 W or 100 W and a pulse rate of 1 kHz or more, preferably 10 kHz or more at a pulse duration of approximately 100 to 200 ns is used, and the feed is 1000 mm / min Or more. On the other hand, the pulse rate in the conventional method is within approximately the same magnitude range, and the pulse frequency is certainly lower, e.g., 50 to 140 Hz.

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

The workpiece manufactured in accordance with the above method may be, for example, a connecting rod or crankcase or other workpiece in which the bearing hole or other area is divided by the fracture splitting method.

Workpieces made according to this method can have notches of different depths or different notch distances by varying the feed rate or pulse of the laser. It is particularly preferred that the transfer variation is repeated periodically along the notch.

The laser unit for carrying out the method comprises a laser module, a laser head for focusing the laser beam coming out of the laser module into the workpiece to be processed, and a transport axis acting in the transport direction. The latter is controllable via the control unit so that the feed during laser machining can be controlled. Alternatively or simultaneously, pulse adjustment may also be performed via the control unit.

The notch distance is defined by a period of pulse adjustment, for example, a period of pulse energy ramping or pulse frequency adjustment. Applicant also has the right to claim for it.

In this connection, a very dynamic transfer axis is preferred, which allows for a change in the transfer rate with an acceleration in the range of 0.5 g or more, preferably 1 to 2 g. That is, the feed rate profile can be sinusoidal with high precision, and even in the limit case it can be almost square.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 shows a schematic diagram of a laser unit for making a fracture split notch at the upper end of a larger connecting rod.
Figure 2 is a greatly enlarged view of a fracture split notch made in accordance with the method of the present invention.
Fig. 3 shows the correspondence when the laser output and / or the pulse rate change.
Figure 4 shows the fracture split notch according to the transfer.
5 shows a fracture split notch according to the average laser power.
Figure 6 shows a diagram for emphasizing the dependence of notch depth on the transport of the laser beam.
Figure 7 shows a diagram for emphasizing the transfer rate control, which is a function of time.
Fig. 8 shows a diagram for emphasizing that the notch depth is adjusted according to the average conveying speed by the conveying speed control.
Fig. 9 shows a photograph of the fracture split notch under conditions that can be compared with and without a feed rate control.
10 schematically shows a laser unit which can be used in a laser method with a feed rate control.
11 shows a schematic diagram of the laser head of the laser unit according to Fig.
12 shows a diagram for emphasizing pulse amplitude control of the laser.
13 shows a diagram for emphasizing pulse sequence control of the laser.
Fig. 14 shows a modification of the embodiment according to Figs. 12 and 13. Fig.
Figure 15 shows a diagram showing the effect of transfer and pulse frequency modulation on notch depth.

Fig. 1 shows a sectional view of a large connecting rod upper end 1, which is separated into a bearing seat and a connecting rod side portion by fracture splitting. The course of this fracture split face 2 is predetermined by two fracture split notches 4 (only one of which is shown in Fig. 1) which are opposite to each other, and this notch preferably has a plurality of notch portions 6 In the form of perforations. After forming the fracture split notch 4 in the left and right walls of the connecting rod top portion 1 in FIG. 1, as described above in connection with the prior art, the expanding mandrel is inserted into the connecting rod top portion, The mandrel is appropriately expanded and the upper end of the connecting rod is supported to separate the bearing seats from the rod side portion of the connecting rod wherein due to the structural conditions the precise fitting of the two members by the geometric shape of the fracture- It gets easier.

A fiber laser is used to design the fracture split notch 4, the laser head 8 of which is schematically shown in Fig. A fiber laser of this kind can be basically a diode-excited solid state laser, and the core of the glass fiber constitutes the working medium. The radiation of the solid laser is introduced into the fiber through the oscillation, in which actual laser amplification occurs. The beam properties and beam quality of the laser can be controlled through the geometry of the fiber (glass fiber) so that the laser is largely independent of external influences and has a very simple structure.

After exiting from the working fibers, the laser beam is introduced into the glass fibers and the radiation is guided through the glass fibers to the laser head 8 shown in Fig. 1 and passed through the focusing optics 10 to the workpiece 1 ). In the embodiment shown, the laser beam 12 collides perpendicularly in the radial direction, i.e., the notch axis (the vertical direction in FIG. 1). With such a configuration, there is a disadvantage that the focusing optical device 10 can be dirty with the molten material because the reflection and possible residual molten mule due to the 90 ° oscillation is directly reflected along the optical path. If the oscillation is made obliquely, for example 30 ° or 45 °, possible reflection and residual melt will leave at the angle of reflection (see FIG. 1 "12" ") and therefore no fouling will occur. The oblique oscillation laser unit will be described with reference to Figs. 10 and 11. Fig.

Another disadvantage of 90 ° oscillation is that weak or strong beam control is not possible. In the case of a slope, the geometry of the notch may be further affected by weak control (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. Dependency may be related to the two points mentioned above.

These fiber lasers have excellent electro-optic efficiency and excellent beam quality with a large focal depth and a very compact structure, thus providing a more cost effective solution than conventional lasers with a small build space. Due to the high peak capability and the large concentration capability of the fiber laser, the output density is relatively high, and thus the evaporated portion of the material predominates. However, since some of the energy is converted to heat, there is still a thermal effect of the melt and the environment nevertheless. Residual heat can accumulate, resulting in a separate melting phenomenon, which causes the calculated notch distance to be significantly smaller than the actual notch distance and also other parameters to vary, but these notch distances are also relatively stable.

After machining the connecting rod wall on the left side of Fig. 1, the laser head is rotated by about 180 degrees and the right connecting rod wall is machined. In principle, crossheads can also be used, in which case both wall portions can be machined simultaneously.

In the embodiment described above, the workpiece, i.e., the connecting rod, is fixedly clamped and the laser head 8 is moved at a conveying speed V in the axial direction or parallel to the axis, the laser output 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 speed V is approximately 1500 mm / min. For these parameters, the calculated notch distance will be about 0.00125 mm. In fact, the notch distance K (in this case the laser beam is oscillated at a 45 DEG inclination) is about 0.1 mm.

Fig. 2 is a greatly enlarged view of the upper end of the connection rod, which has been processed in accordance with the method of the present invention, together with the above-mentioned parameters. In this embodiment, the laser beam is oscillated at an oblique angle (45 deg.). The average laser power is about 50 W and the pulse output 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 individual notches 6 forming perforations extend. 2, the depth of the notch base G is about 0.51 mm and the depth P of the notch 6 (seen from the radial direction) is about 0.78 mm (the connecting rod upper end 1) As measured from the circumferential wall 14 of the chamber.

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

Fig. 4 shows the dependence of the fracture 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 even at different feed rates (500 mm / min, 1000 mm / min, 1500 mm / min). Obviously, at a lower feed rate, on the one hand, the depth G of the notch base becomes larger and the axial length PG of the notch is inversely proportional to the feed, where the difference between 500 mm / min and 1000 mm / min It is relatively small.

Figure 5 shows the dependence of the fracture splitting notch on the laser output. As shown at the top of Fig. 5, the average laser power was set at 50W. The fracture split notch shown below was obtained at an average laser power of 100 W, at which time the other parameters did not change. As can be appreciated, when the laser power is reduced, a rather fine notch structure with a longer notch is formed, but the notch distance is substantially unchanged as already mentioned above. Moreover, reducing the laser output, as expected, forms a continuous notch base with a slightly smaller depth (G) than in the case of larger laser power. In terms of fracture mechanics, it is best to use a laser with a relatively small laser power (less than 50 W) at an average feed rate in the range of 500 to 1500 mm / min.

The beam quality can be improved by a so-called Q-switch. This Q-switch is an optical element. In the case of a pulsed laser, the pulse is delayed by the switch, the pulse duration is reduced, the pulse height (peak performance) is increased, and thus a very sharp laser pulse is obtained. This laser pulse rapidly increases and rapidly decreases again when the maximum sharpness is reached. Without such a Q-switch, the pulse is clearly wider and more flat.

Figure 6 shows the dependence of the notch depth on the feed rate varying from 100 to 3000 mm / min. In this regard, the measurement S2 corresponds to the prescribed measurement G (the depth of the notch base), the measurement S1 corresponds to the total depth P of the notch (see Figs. 2 and 3) The length of the notch corresponds to the car GP. The upper curve represents the transition of the total depth S1 of the notch and the lower curve represents the transition of the depth S2 of the notch base. As is evident, at relatively low feed rates in the range of up to about 800 mm / min, a relatively strong dependence of notch depths S1 and S2 appears. At higher feed rates (approximately 800 to 3000 mm / min), the dependence is even smaller. These experiments were performed at a pulse frequency of 50 kHz and an average pulse output of 50 W. FIG. In this way, the dependence of the geometry of the notch on the transport speed as shown in the above-mentioned figures was confirmed by the experiment shown in Fig.

As will be explained in more detail later, at very low feed rates (below 200 mm / min), notch quality is insufficient due to thermal overheating in the notch base area. A blackened area was formed, which caused the laser-machined workpiece to be of no practical use. The blackened area is shown at the top of FIG. 9 to be described in more detail below.

Therefore, in laser machining, care is taken to control the feed rate so that this quality loss does not occur when forming the fracture split notch.

It has been found that changing the feed rate during the laser machining can avoid this phenomenon, on the one hand creating a fracture split notch that has a sufficient notch depth and, on the other hand, can be formed in a short time at a high feed rate, No qualitative loss is expected to impair fracture mechanics.

Fig. 7 shows an example of the conveying speed control, in which the conveying speed control is performed in accordance with a sine function. Of course, the feed rate adjustment may also be performed according to another function, preferably a periodic function. The transition of the conveying speed within a specific conveying range which does not correspond to the total length of the breaking split notches to be formed is shown as a function of time. In this case, the conveyance range of 67.5 to 69.5 mm is specifically shown, i.e. only two 2 mm total fracture split notches are shown, but the conveyance speed adjustment is correspondingly carried out in the region of the fracture split notch (not shown). The curves (upper curve and lower curve are shown as a dashed line and a dashed curve, respectively) are shown as a slightly wavy curve from the upper left to the lower right, as a function of time (t) in the direction of the fracture split notch will be. During this somewhat wavy transfer, the transfer rate varies with the sine function being represented, where the sine function with the higher amplitude is assigned to the laser path as a one-dot chain line, and the sine function with the smaller amplitude, Lt; / RTI > It can be seen that the feed rate varies at a relatively high frequency and therefore the laser head 8 must be significantly accelerated and decelerated within a short time to adjust the motion profile along the fracture split notch to be formed.

In the diagram according to Fig. 7, the actual values of the respective conveying speeds to be adjusted are shown on the right. Therefore, the feed rate at the top speed control varied within the range of 117 ~ 1157 mm / min. When forming the fracture splitting notch in such a conveying speed adjustment, the geometrical shape of the fracture splitting notch as illustrated in Figs. 8 and 9 is obtained. 8 shows the function, that is leading is adjusted as a function of the mean value of the above-described speed control of the depth of the notch is generated average feeding (V _m). As can be seen in Fig. 8, a fracture splitting notch having a transition shown in Fig. 8 is generated in the case of an average feed speed of 800 mm / min (in fact, the feed rate varies with the sine function according to Fig. 7) . As is evident, different notches are formed from the notch base with measurements S2 (G) corresponding to the sign period. The notch portion denoted by S3 is formed in a region where the feed rate is relatively low. The notch indicated by S1 is formed in the region where the laser moves at a relatively high speed.

  The transition of the characteristic parameters S1 (P), S2 (G), and S3 (P) according to the average transfer is shown in the diagram according to FIG. The curve S1 represents the transition of the notch depth at a relatively high feed rate (during constant speed control) and the curve S2 represents the depth of the notch base S3 . As the average feed rate increases, the notch depth decreases. However, as can be appreciated, notches having a variable notch depth may be formed at each speed adjustment. These notches have significantly improved the fracture mechanics compared to the notches mentioned at the beginning. In other words, by controlling the feed rate, a relatively deep and sharp initial notch can be formed which reliably improves the initial fracture toughness and the arcing fracture toughness compared to the fracture split notch comprising continuous perforation without a feed rate adjustment.

Thus, complicated elements can also be cracked, wherein the adjustment of the feed rate can be performed according to the geometric shape of the element. That is, for example, in a very complex element that includes a breakthrough in the region of a fracture split notch, the feedrate may be adapted to the geometry of the element, and thus in a relatively uncomplicated region a relatively high The feed rate or amplitude is applied and in the more important region the feed rate control is appropriately reduced so as to be adjusted to a lower average feed rate or a constant feed rate.

Advantages of the aforesaid feed rate control are highlighted in Fig. The top shows a fracture split notch controlled at a relatively low constant feed rate of 200 mm / min. At relatively low feed rates, a relatively large notch depth and burned / blackened areas that can be caused by high heat input can be seen. Such fracture split notches are practically useless.

On the other hand, the lower photograph shows a notch obtained according to the method of the present invention in which the feed rate control takes place, the feed rate being adjusted in the range of 117 to 1157 mm / min. As can be seen, this adjustment reliably avoids combustion in the notch base region. It is also possible to see a notch with a larger or smaller depth formed by an appropriate speed adjustment, the depth also depending on the tilt angle of the laser. In the embodiment shown, the tilt angle, i. E. The tilt angle, is about 30 degrees with respect to the horizontal in FIG.

Referring to Figs. 10 and 11, a laser unit particularly well suited for carrying out the above-described method in which the conveying speed adjustment takes place will be described. According to Fig. 10, the laser unit includes a laser module 16, which includes, for example, a fiber laser and a control part of the fiber laser. The control unit 16 of the laser unit is configured so that the conveying speed of the laser beam can be adjusted in the manner described above.

The laser beam 12 generated by the laser module 16 is guided to a re-collimator 20 which is simply shown in FIG. In the recollimator, the laser beam is converted into a parallel beam, and the beam diameter is in the range of approximately 6 mm. The parallel beam is then guided to the laser head 8 via the light transmitter 18 and then the laser beam is transmitted via the laser head to the workpiece to be processed (in this case the connection rod upper end 1 ). The concentrated laser beam is oscillated at an angle of 30 degrees with respect to the horizontal in Fig. The laser head 8 has a Z transfer axis 22 through which a transfer takes place in the longitudinal notch axis. The transport axis is a very dynamic axis, which allows extremely high acceleration to be achieved with high closed loop gain and large jerk, thus requiring extremely precise control of regulation. The acceleration may range, for example, from 1 to 2 g, and the closed loop gain may be in the range of 10 n / min / mm (166.71 / s) and the jerk may be greater than 400 m / s ³ . When machining both sides of the connecting rod top portion 1 the laser head 8 has a further pivot axis 24 which causes the laser head 8 to be pivoted about the Z transport axis 22 . The laser unit also includes an X adjusting axis 26 through which the entire laser head 8 can move in the X direction (radially with respect to the connecting rod upper end 1). By this means a serpentine fracture split notch can also be formed.

Fig. 11 shows a basic structure for guiding the beam in the laser head 8. This figure shows a light transmitter 18 connected to a fiber laser (laser module 16). In the recollimator 20, the laser beam is converted into a parallel beam having a diameter of approximately 6 mm and then turned by 90 ° in the direction of the connecting rod upper end axis by the turning mirror 28. The redirected laser beam 12 is then focused on the connecting rod top wall via an optical device having a focal length of, for example, 100 mm, and the orientation of the circumferential wall of the connecting rod is directed to the other direction changing mirror 32 In which the other directional mirror is inclined at an angle of 60 degrees with respect to the horizontal so that the laser beam impinges on the circumferential wall of the connecting rod so as to obtain an oscillation angle of 30 DEG with respect to the horizontal, Is inclined at an inclination angle of 60 DEG with respect to the vertical portion of the laser beam 12 impinging on the switching mirror 32 (60 DEG direction switching). The laser beam exits through the nozzle 34 and is thus focused so that the laser point is located about 3 mm before the exit face of the nozzle 34. A protective glass 34 is provided in the optical path between the nozzle 34 and the redirecting mirror 32 to avoid the optical instrument 30 and the mirrors 28 and 32 being dirty. In Figure 11, a pivot axis 24 is also visible, the laser head 8 pivoted through the pivot bearing 38 and is connected to a motor (not shown) so that it can actually reach all the circumferential wall areas of the connecting rod And can be pivoted about the Z transport axis 22.

When fiber lasers are used and when the feed rate control and a relatively high pulse rate (as compared to conventional solutions) are chosen appropriately, an optimum stress concentration with substantially lower energy input and significantly faster feed rate than in conventional systems A perforation having a coefficient can be formed.

Experiments performed show that for a fiber laser with an output of 50 W at a pulse frequency of, for example, 20 kHz, the notch 6 has a fracture split notch having a distance in the range of 1/10 mm, preferably 0.1-0.3 mm, (4) may be formed. It has been shown that a very effective perforated fracture split notch 4 can be formed even when a laser with an output power of only 30 W is used.

In the above-described embodiment, the conveyance adjustment is performed. Alternatively or additionally, pulse modulation may also occur in a manner to be described later, for example.

In principle, in such pulse conditioning, the pulsed carrier or fundamental function is adjusted, in which case the pulse width, pulse duration or pulse phase may be varied. Preferably, the pulse energy (pulse ramping) or pulse frequency / pulse sequence is adjusted. When adjusting the pulse amplitude, the rectangular carrier pulse sequence changes with a change in the pulse amplitude. When adjusting the pulse duration, the pulse width of the underlying carrier function is appropriately changed. Correspondingly, the pulse position in the pulse phase is phase shifted for each carrier function, where a constant pulse width and pulse amplitude are used.

Hereinafter, the pulse-frequency-ramping of the pulse frequency and the pulse-sequence control of the approximately constant pulse power are described.

In time controlled pulse energy ramping, the time control is adapted to the current, preferably constant, feed rate and desired notched grid (the perforation grid). In this case, the shape of the pulse energy ramp indicates roughly the shape of the perforation.

In Fig. 12, such adjustment is shown in which time controlled pulse energy ramping occurs. The transition of the pulse energy (E _KI ) as a start or carrier function is shown with time, where the pulse energy is 1 mJ at a pulse length of, for example, 120 ns and a frequency of 50 kHz. This carrier function is superimposed by the ramp type adjustment of the pulse energy (P _Ramp ) (its transition is shown in Fig. 12). In the embodiment shown, the pulse ramp shape has a substantially sinusoidal shape that does not intersect the zero. However, in principle, other ramp shapes with increasing and decreasing side portions and normal flat portions of constant power / energy may also be used. In the embodiment shown, adjustment of the start or carrier function is performed such that a predetermined maximum pulse energy (1 mJ) is periodically decreased, such a decrease and the associated increase in maximum pulse energy (ramping) has a roughly sinusoidal transition .

Appropriate regulation of the carrier function (E _KI ) results in a pulse energy change (E _Ramp ) with a ramp shape. The time sequence of the ramp, i. E. The pulse energy ramp shape, defines the notch distance K, so that the pulse energy ramp shape represents a perforated shape. In this embodiment a constant feed rate is provided, in the embodiment shown, the feed rate is approximately 200 mm / min and the pulse frequency / period of function P _Ramp is always 11.1 Hz. The pulse energy (E _Ramp ) of the laser changes in accordance with the ramp function at the same frequency, and the notch K is adjusted according to the frequency and the selected feed rate. Thus, also in this embodiment, the notch distance K, which is clearly larger than that obtained from the actual pulse frequency (see function E _KI ) and the selected feed rate, is adjusted because such notch distance K is substantially / RTI > depends on the selected frequency / period (11.1 Hz) of the ramp function.

13 shows an embodiment in which pulse sequence or pulse frequency adjustment occurs. Similar to the previous embodiment, an output or carrier pulse sequence having a pulse energy of 1 mJ and a pulse length of 120 ns is taken as a basis. This output function is adjusted by varying the pulse frequency during the pulse sequence adjustment between a maximum value of 100 kHz and a minimum value of 20 kHz, wherein the change is also performed in a roughly sinusoidal manner according to FIG. And the period or frequency variation of this pulse sequence determines the notch distance K. [ It can clearly be seen that the maximum notch depth is formed in the region with a pulse power of 1 mJ and a high frequency in the 100 kHz range. Thus, the notch depth depends on the pulse frequency (when the pulse power is constant). In the embodiment shown, the period of pulse modulation is 11.1 Hz. The feed rate is 200 mm / min. This adjustment of the carrier function results in a pulse sequence adjustment (E _KIPf ) in which the pulse sequence varies from 10 to 50 μs at a modulation frequency (pulse train period) of 11.1 Hz.

Similar to the embodiment according to Fig. 12, the notch distance K in this pulse sequence adjustment is obtained in the period (11.1 Hz), so that the frequency period (pulse sequence control) or cycle A proper selection results in a perforated grid, the notch distance (K). In the described embodiment, a notch distance of 0.3 mm is adjusted. This type of adjustment is also referred to as "frequency fluctuation ".

Fig. 14 shows, in a very general form, an embodiment in which the notch depth or notch distance is changed by a change in the pulse power P, which power adjustment is performed dynamically. The pulse width and pulse amplitude and the pulse frequency are also changed if appropriate.

Basically, a burst mode can also be used during pulse conditioning, in which laser pulses are output from the energy storage device until a fixed number of pulses is reached or until the energy storage device is discharged. In this case, the fracture split notch is considered to be fully formed and the workpiece is transported to another station. The energy storage device is charged during such work handling and is therefore ready for the next laser machining.

With reference to the diagram shown in FIG. 15, the fact revealed by the present invention will be summarized again. This diagram shows the notch depth as a function of feed and pulse frequency.

As described in detail above, a large notch depth is obtained at a relatively low feed rate, and the notch depth at the time of adjusting the pulse frequency increases as the frequency increases. Thus, when the feed rate is constant, the notch depth at high frequencies (100 kHz) is almost twice that of the 50 kHz pulse frequency. In this case, a laser having an average power of 100 W is used with a pulse energy of 1 mJ, a pulse length of 130 ns, and an oscillation angle of 90 [deg.].

As already described repeatedly, the feed rate and the laser pulse can be adjusted. Applicants tend to vary the feed rate at the maximum laser power, since the notch depth is almost linearly dependent on the control of the feed rate, so that the maximum laser power can always be used for the work. Using linear motor technology, the machining time can be reduced considerably, and the feedrate adjustment is possible in a relatively simple manner. If the laser includes scanner technology, the adjustment can be made even easier, and the alignment of the laser is done through a tilted mirror or an optical instrument, and thus a linear axis is usually not needed.

The present invention relates to a method for fracture-splitting a workpiece and to a workpiece produced by such a method. According to the invention, the feed rate and / or the laser pulse are adjusted according to the geometry of the workpiece and / or the laser power during laser machining.

1 connection rod top
2 fracture surface
4 fracture split notch
6 notch portion
8 laser head
10 Focusing optics
12 laser beam
14 Cylindrical wall
16 laser modules
18 Light transmission
20 recollimator
22 Feeding axis
24 Pivot axis
26 Control axis
28-way mirror
30 Optical equipment
32-way mirror
34 nozzle
36 Protection Glass
38 Pivot bearing

Claims (15)

A method for destructively dividing a workpiece (1) with laser energy, characterized in that a fracture splitting notch (4) predefining a fracture splitting surface (2) is formed by relative displacement between the laser beam (12) And the breaking split notch 4 is in the form of a perforation including the notch 6 and the pulse parameter of the laser changes while forming the breaking split notch 4,
Wherein the pulse adjustment is performed by varying at least one of a pulse width, a pulse frequency, a pulse amplitude, and a pulse phase, the parameters being adjusted individually or in combination,
A method for fracturing and splitting a workpiece with laser energy. The method according to claim 1,
Wherein the laser beam (12) is oscillated obliquely with respect to the longitudinal notch axis. The method according to claim 1,
A method for fracturing and splitting a workpiece with laser energy, wherein a feed rate (V) of the laser varies during formation of the fracture split notch (4). The method of claim 3,
Wherein said feed rate (V) varies with a periodic function. The method of claim 3,
Wherein the conveying speed (V) varies from 100 mm / min to 1500 mm / min. The method according to claim 1,
Wherein said pulse conditioning is performed with time controlled pulse energy ramping at a constant pulse frequency. The method according to claim 1,
Wherein said pulse adjustment is performed by pulse sequence or pulse frequency modulation with constant pulse power. The method according to claim 1,
Wherein the laser used is a fiber laser, wherein the laser energy destroys the work piece. 3. The method according to claim 1 or 2,
The breaking split notch (4) has a continuous notch base with a notch (6) extended. delete A laser unit for implementing a method for fracture-splitting a workpiece with laser energy according to claim 8,
Fiber lasers,
A laser head (8) for focusing a laser beam (12) on a workpiece to be machined, the laser head (8) comprising at least one transfer axis (22)
A control unit (16) for changing the pulse parameters of the fiber laser during formation of the fracture split notch (4)
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Wherein the pulse adjustment is performed by varying at least one of a pulse width, a pulse frequency, a pulse amplitude, and a pulse phase, the parameters being adjusted individually or in combination,
Laser unit. 12. The method of claim 11,
Wherein the control unit (16) changes the feed rate (V) of the fiber laser during formation of the breaking split notch (4). 13. The method of claim 12,
Wherein said transfer axis (22) is such that the change in the feed rate (V) during the formation of the fracture split notch (4) is made possible with an acceleration greater than 0.5 g. 13. The method according to claim 11 or 12,
Wherein the average power of the fiber laser is 100 W or less at a maximum pulse rate of 20 kHz or more. 13. The method according to claim 11 or 12,
Wherein a period of adjustment of the pulse of the laser is selected such that a predetermined notch distance (K) is adjusted.

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