CN1134322C - Material shaping device with laser beam which is injected into stream of liquid - Google Patents

Abstract

The invention relates to a method and device for shaping material of work pieces (45) using a laser beam which is injected into a stream of liquid (25). The liquid which is to be formed into a stream (25) by a nozzle channel (29) is fed to the nozzle channel opening (28) such that the flow does not swirl, especially without flow components which are tangential to the nozzle channel axis (32). The laser irradiation is focused on the channel entry plane (30) and the liquid is fed to the channel opening (28) in such a way that a liquid retention space is avoided in the beam focussing ball (38) and in the immediate surroundings thereof.

Description

Apparatus and method for material processing using a laser beam incorporated into a liquid jet

The invention relates to a material processing method of workpieces using a laser beam incorporated into a liquid jet and a material processing device having a laser radiation source and a liquid jet formed by means of a nozzle channel of a nozzle block, A laser beam of a laser radiation source can be incorporated into the liquid jet.

current technology

Materials processing with laser beams is widely used for cutting, perforating, welding, marking and generally for grinding materials. In order to be able to start material removal, a predetermined laser radiation intensity must be reached on the material surface to be processed. This high laser radiation intensity was originally achieved by focusing the laser beam at a focal point. A disadvantage of this is that the focal point still has a small axial extension (beam radius) in which the above-mentioned high laser radiation intensity is achieved. If deep cuts or deep holes are to be made, the focal point must be maintained very precisely, or even tracked. The laser beam narrows conically towards the focal point, which means that, especially with deep cuts, so much material must be continuously removed starting from the material surface that the conical laser beam can also be continuously cut. Proceed to the processing point. Therefore, deep cuts or deep perforations must always have beveled side walls.

In order to avoid the above-mentioned focus tracking guidance, and in order to carry out narrow cuts and narrow perforations with approximately vertical side walls, it is proposed in US-A 5 773 791, EP-A 0515983, DE-A 3643284 and WO 95/32834 that the laser The radiation is merged into a liquid jet which acts as a light conductor and is aimed at the workpiece to be processed.

In DE-A 3643284 the laser beam is delivered by a glass fiber. The fiberglass ends are flushed around by a water jet directed at the workpiece being machined. A disadvantage of this known device is that the diameter of the water jet must never be smaller than the diameter of the glass fiber which conveys the laser beam. Its other disadvantage is caused by a dead water zone under the glass tip, which also creates disturbances in the water jet, which eventually leads to a rapid breakup of the water jet into droplets.

EP-A 0515983 once tried to overcome the above-mentioned shortcoming, for this reason, designed an optical device that is equipped with the nozzle block that forms water jet. In front of the nozzle forming the water jet there is a stagnation chamber with a water inlet and a focusing lens which closes the stagnation chamber opposite the nozzle inlet for focusing the laser beam. The position and focal length of the focusing lens are selected such that the focal point of the laser beam lies exactly in the axial center within the nozzle channel. During machining operations it has been found that the nozzles are damaged very quickly by the laser beam, so that perfect laser beam shaping can no longer be achieved.

In WO 95/32834 the method of incorporating a laser beam into a liquid jet is improved by placing the focal point of the laser beam to be incorporated in the plane of the nozzle opening and eliminating the stagnation chamber in front of the nozzle opening. The nozzle forming the liquid jet is located here in a liquid supply chamber extending radially to the nozzle axis, into which a plurality of coaxially distributed axial liquid channels open. Even with this arrangement, damage to the nozzle can occur during material processing operations.

Tasks of the invention

The object of the present invention is to provide a material processing method and a material processing device using a laser beam incorporated into a liquid jet, with which material processing can be carried out while ensuring a long machine operating life. Machining operations are only interrupted during scheduled maintenance intervals. Unforeseen interruptions, in particular due to damage to the nozzle block forming the liquid jet, are ruled out.

Technical solutions

Care should be taken according to the invention that, on the one hand, the laser beam incorporated into the liquid jet should be focused in the nozzle inlet plane of the nozzle channel forming the liquid jet; ) and no liquid vortex. According to the three related requirements mentioned above, the corresponding design of the following optical device is completed.

The device of the present invention preferably has a nozzle channel length as short as possible, which is preferably less than twice the diameter of the nozzle, and the nozzle channel outlet has a conical outlet section whose opening angle is greater than a Splitting of the incorporated laser beam due to instabilities occurs, preferably in the case of laser radiation whose wavelength is in the range of 150 nm to 1100 nm, especially in the range of 190 nm to 920 nm and 1040 nm to 1080 nm, the opening angle is greater than 60 ° in particular greater than 80°.

In the device according to the invention, the outlet of the nozzle which is designed to be tapered is provided with a reflective coating for the laser radiation, in case the wavelength of the laser radiation source used is in the range of 150nm to 1100nm, especially in the range of 1040nm to 1080nm, Nozzle blocks are best made of quartz, especially diamond.

Embodiment of the invention

Embodiments of the method proposed by the present invention and the device proposed by the present invention will be described in detail below with reference to the accompanying drawings. Further advantages of the present invention are given in the text of the description below. The accompanying drawings indicate:

The cross-sectional view of the optical device of the material processing device that Fig. 1 present invention proposes,

Figure 2 is a longitudinal sectional view of the optical device shown in Figure 1, showing enlarged liquid supply lines to nozzle blocks forming liquid jets,

Fig. 3 is a longitudinal sectional view of a nozzle block held in a nozzle holder shown in Fig. 2,

Figure 4 is a cross-sectional view along line IV-IV in Figure 2,

FIG. 5 is an enlarged view of the part shown in FIG. 3, showing in particular the formation and guidance of the liquid jet in the nozzle channel.

The optics 1 of the material processing device proposed by the invention, shown in cross section in FIG. 1 , is connected to a laser radiation source 6 with a beam conductor 3 via a beam conductor plug 5 . The laser radiation source 6 is shown only symbolically in the figure. It is a high power laser, such as a Nd:YAG laser. The beam 7 emerging from the beam guide 3 in the plug 5 is collimated by means of a collimator 9 into a beam 10 . The beam 10 is guided to a beam expander 11 . With the diameter expander 11 the diameter of the incoming beam 10 can be changed, ie enlarged, to the diameter of the outgoing beam 13 . A diameter factor of 2 to 8 is given here for beam expansion. This expansion ratio allows the beam width 15 (diameter of the focal point) of the laser beam 13 described below to be varied. The beam expansion factor of the beam expander is varied electrically via a signal from an adjustment device (not shown in the figure) (“motorized beam expander”). The expanded beam 13 is then deflected by 90° with a flat deflecting mirror 17 and deflected with a further flat deflecting mirror 21 with adjustment device 19 onto a focusing lens group 23 as focusing device. The mode of operation and application of the adjustment device 19 will be described below.

It must be pointed out that the theoretical focal point of the focusing optics 23 does not necessarily coincide with the beam width 15 of the focused laser beam 13 . The above-mentioned deviation of the two positions is due to the beam divergence of the laser beam 13 , which can also be modulated by means of the beam expander 11 .

A nozzle block 27 with a nozzle channel 29 is used for forming the liquid jet 25 . The focusing optics 23 and the beam expander 11 are set or installed in such a way that the beam width 15 of the focused beam 13 lies exactly in the nozzle channel entry plane 30 of the nozzle channel opening 28 . The nozzle channel inlet plane 30 continues into the surface of the nozzle block 27 on both sides. 2 to 5 show the immediate area around the inlet into the nozzle channel 29 forming the liquid jet. The nozzle block 27 is shown in the enlarged part of FIG. 3 compared to FIG. 2 . The nozzle channel 29 is designed cylindrically. The nozzle block 27 is made of a mechanically hard material, such as quartz, which is transparent to laser radiation (here with a wavelength of 1.06 μm). But since it's designed to be extra small, it can also be made of diamonds. A nozzle block 27 made of diamond has a longer service life than a nozzle block made of quartz, wherein the end of the service life can be manifested by a beaded liquid jet 25 after a short liquid jet length.

In order to take advantage of the conditions of total reflection at the walls of the nozzle channel, it is not necessary for the nozzle block to be made of a material which is transparent to the laser radiation. It can also be made of an opaque, radiation-absorbing material, as long as the walls of the nozzle channel are provided with a laser radiation-reflecting coating which is resistant to the liquid jet. In the case of opaque nozzle block materials, the surface of the nozzle block should also be coated with a reflective coating (for protection, in the event of alignment errors), as well as the underside of the nozzle block (for radiation protection, this radiation is reflected from the workpiece or plasma cloud onto the workpiece).

The nozzle block 27 shown in FIG. 3 has a flat surface 30 to which the axis 32 of the nozzle channel 29 extends perpendicularly. The edge 31 on the nozzle channel opening 28 is designed as a sharp edge between the surface 30 and the channel wall, preferably with a radius of less than 5 microns. Such a rounded edge 31 is one of the other prerequisites for producing a liquid jet 25 with a large liquid jet length, which will be described below. That is, it can inhibit the formation of liquid vortices. The nozzle block 27 is inserted into a nozzle holder 33 . The transition region 34 between the nozzle seat 33 and the nozzle block 27 is designed so that no steps exist. Even a single step produces swirls in the liquid which continue into the liquid jet 25 formed by means of the nozzle channel 29 . The nozzle block 27 shown in FIG. 3 has an outer diameter of 2 mm and a height of 0.9 mm. Nozzle blocks in the above size classes made of one diamond still remain within acceptable cost.

As already mentioned above, the nozzle channel 29 forming the liquid jet is designed here as a cylinder with a diameter of, for example, 150 μm and a length of approximately 300 μm. The length of the nozzle channel 29 should not be greater than twice the diameter of the nozzle channel. Adjoining the outlet of the nozzle channel 29 is a conically widening orifice 26 . The apex angle of the cone is here 80°. The inner surface 35 of this cone extends steplessly into the nozzle seat 33 .

The conical design of the inner surface 35 facilitates the application of a reflective layer which in no way hinders the liquid jet and, due to its inclination, enhances any mechanical inhomogeneities from the liquid jet 25 (shock waves, filtered still). The reflection behavior of the outgoing beam from the carried-in contaminating impurities...). The size of the cone angle is selected such that the jets emerging from the liquid jet do not hit it at all or only at a very flat angle.

The liquid supply to the nozzle channel 29 takes place via a narrow disk-shaped inner chamber 36 whose height corresponds approximately to half the diameter of the nozzle channel 29 . The diameter of the inner chamber 36 corresponds to the diameter of the nozzle holder 33 . Twenty supply lines 37 with a circular cross section arranged in a star form radially into the inner chamber 36 with respect to the axis 32 of the nozzle channel 29 , the adjacent side walls of these lines leading into the interior. When in the chamber 36, they merge with each other. This arrangement of the supply line 37 supports a swirl-free (radial) liquid delivery to the nozzle channel 27 . On the inlet side of the supply line 37 a pressure reduction filter 39 is arranged. Connected to the filter 39 is an annular chamber 40 which is supplied with liquid via a supply line 41 . The function of the filter 39 is to create a uniform liquid pressure in the twenty supply lines 37, thereby providing a symmetrical flow of liquid to the nozzle inlets. Since the supply lines 41 are only together, there is no filter 39, and the supply line 37 adjacent to the supply line 41 has a higher pressure than the opposite supply line. In the region of the nozzle channel opening 28 there is therefore no tangential flow split. In order to allow the laser beam to reach the nozzle inlet, the disk-shaped inner chamber 36 is closed liquid-tight with a cover 43 which is transparent to the laser beam used.

Due to the small height of the inner chamber 36, a high flow rate of the liquid is obtained. Due to the high flow rate, heating of the liquid in the focusing cone 38 by the laser beam passing through it is ruled out (or such heating is greatly reduced). Due to the above-mentioned design of the disk-shaped inner chamber 36 , it is not possible to form a liquid stagnation chamber, especially in the radiation focusing cone 38 of the laser beam, which preferentially promotes the formation of thermal lenses through radiation absorption. A thermal lens would make it impossible to perfectly and stably focus the laser beam on the center (axis 32 ) of the nozzle channel opening 28 . The presence of a thermal lens results in poorer focusing of the laser beam, since the thermal lens acts as a scattering lens. The laser beam can hit the edge of the nozzle opening and/or the nozzle surface and damage them. In addition, the thermal lens formed by the heating of the liquid does not have a stable position. In this case, the laser beam can no longer be merged optimally into the liquid jet 25 .

Through the star-shaped (radial) arrangement of the supply line 37 , through the pressure-reducing filter 39 between the inlet of the supply line 37 and the annular chamber 40 , through the absence of pressure in the liquid flow area between the nozzle block 27 and the nozzle seat 33 The step transition zone 34 and the slight (rounding radius < 5 μm) rounding of the edge 31 through the liquid inlet into the nozzle achieve a vortex-free flow, which is required for the liquid jet 25 with a large jet length. prerequisites. In addition, the degassing of the liquid and the removal of particles in the liquid also play a positive role in producing large jet lengths. It must also be taken into account that the liquid supply is free of pressure pulsations. The cylindrical shape of a free liquid jet is unstable. A liquid, because of its surface tension, always tries to become another shape, namely a sphere. In this way, after a certain expansion length, the liquid jet breaks up into discrete droplets. An infinitesimally small radial perturbation of the liquid jet intensifies rapidly as the jet is forming, possibly producing a jet constriction that destroys the jet. In addition, the air surrounding the liquid jet due to friction also intensifies the above-mentioned effect. A liquid jet with a large jet length can only be achieved by the above-mentioned measures for achieving an undisturbed liquid jet.

Furthermore, it has surprisingly been found that as soon as the liquid jet 25 hits an unprocessed workpiece surface, a shock wave begins to move upwards in the jet. Due to this shock wave, the liquid jet is no longer laminar, and a part of the laser beam merged into the liquid jet 25 at the entrance of the nozzle opening is ejected from the liquid jet 25 because the Wave-induced inhomogeneities appear on the inside surface of the liquid jet due to it. The above-mentioned part of the emitted jet may hit the nozzle block 27 , pass through the nozzle block and then hit the metal wall of the nozzle holder 33 . Here, under localized heating, the beam is absorbed. At this time, the material of the nozzle seat 33 may melt or vaporize as a result, resulting in damage to the nozzle block 7 and the nozzle seat 33 . In order to prevent the occurrence of the above phenomenon, the inner wall 35 is designed to be tapered, and a reflective coating is applied. In this way, the part of the laser beam that emerges due to inhomogeneities on the inner surface of the liquid jet is reflected there and thus does not pass through the nozzle block 27 as far as the absorbing material. As soon as the workpiece 45 is drilled or cut off, no shock waves are generated, or only shock waves with only minimal energy are generated.

Although the nozzle block 27 has a relatively long service life in the arrangement described here, it is also arranged so that it can be easily replaced. Only need to screw out the connector 46 during replacement.

For the purpose of tightness testing, the joint 48 housing the transparent cover 43 has on its outer surface a circumferential slot 54 which merges into the testing hole 50 . That is to say, if there is liquid in the detection hole 50, it proves that the sealing ring 58a is not tight. If the sealing ring 58b is not tight enough, liquid can reach the surface 60 of the transparent cover 43, which can lead to severe damage to the focusing and guiding of the laser beam. In order to avoid the above-mentioned points, the sealing rings 58a and 58b must be replaced in time as soon as liquid is registered in the detection hole 50 .

A force sensor 47 is arranged below the workpiece 45 to be processed. The position of the force sensor 47 is selected such that it emits a maximum electrical signal to the control device 49 when it is completely touched by the liquid jet 25 (without deflection). The force sensor 47 is arranged on the geometric axis 32 of the liquid jet 25 . If the liquid jet 25 with the integrated laser beam touches an as yet unprocessed workpiece 45 , there is no signal, since this workpiece 45 must first be perforated by the liquid jet 25 . If this workpiece 45 has been perforated or it has been cut through by the liquid jet 25, then the liquid jet 25 just touches the kerf side wall or the perforation wall when moving the workpiece 45. In this case still only a part of the liquid jet 25 hits the force sensor 47 . The signal sent to the control device 49 is smaller than the signal sent when the liquid jet 25 makes full contact. Thus, by means of the force sensor 47 it is possible to determine the amount of material that has been removed.

Furthermore, the control device 49 is also connected to the displacement device of the workpiece 45 . This displacement means is only symbolically indicated in FIG. 1 by two double arrows 51a and 51b pointing in the horizontal directions X and Y, which indicate that the displacement can be realized in one plane and in two dimensions. At this time, the control device 49 controls the displacement speed of the workpiece 45 according to a predetermined cutting pattern in the two directions 51a and 51b based on the obtained value of the force sensor 47 . In this way, the feed rate of the workpiece 45 to be processed can be adjusted in an energy-optimized manner by means of the force sensor 47 , for which the workpiece 45 is always moved whenever a sufficient material removal is achieved.

Furthermore, the control device 49 is also connected to a radiation source 6 . Therefore, the output power of the laser can also be adjusted according to the measured value of the force sensor and the displacement speed of the workpiece. If, in the case of a pulsed laser, a stepping mode is used, for example, for the displacement of the workpiece, the laser emits a plurality of pulses at one position before the workpiece 45 is moved one step forward. The step mode can be performed, for example, with a step sequence frequency of 100 Hz.

In addition to the beam steering of the laser beam described above, the optical device 1, as shown in FIG. 1, has means to optimally correct and monitor the laser beam amplitude ( the location of the focus of the radiation). For this purpose, the radiation 52 emitted by the white light source 53 is superimposed congruently on the expanded laser beam 13 . This is achieved using a turning mirror 17 . The deflection mirror 17 completely reflects the laser radiation, but transmits the white light radiation 52 of a white light source 53 located behind it. The radiation of the white light source 53 is guided together with the laser radiation via the deflecting mirror 21 into the focusing device 23 and focused on the position of the axis 32 under correct optical alignment in the nozzle inlet plane 30 . The deflection mirror 21 is designed to be partially transparent to the white light radiation 52 .

In order to check whether the beam alignment is correct, only the radiation of the white light source 53 is used and no laser beam is used. If there are any erroneous corrections, the white light radiation focused by the focusing device 23 illuminates the nozzle edge 31 or the area around the nozzle edge. The area around the surface of the nozzle inlet is observed using a camera 55 via a telescope 56 and turning mirror 21 which is partially transparent to white light radiation. White light undergoes a beam dislocation when passing through the turning mirror 21 due to the thickness of the mirror. This beam misalignment is corrected with a plane-parallel glass plate 57.

The deflection mirror 21 can be tilted by an adjustment device 19 . The deflection mirror 21 is tilted by means of the adjusting element in such a way that the focal point of the white light beam is exactly symmetrical to the position of the nozzle channel axis 32 .

射束在喷嘴通道口上的移位距离)的条件下朝反方向倾斜，直到在相对峙的喷嘴通道边缘31上也能确定出具有同一反射强度的一种辐射反射为止，然后以半倾斜角进行重新的回倾运动。这时，焦点便处在一个包含喷嘴通道轴线32的平面中。为了对准在通道轴线32的位置上，于是垂直于原先的倾斜方向进行另一次相似的射束轴线调定。In order to achieve this purpose, the following steps can be carried out: the turning mirror 21 is tilted until a radiation reflection can be determined on the edge 31 of the nozzle channel, and then after measuring the tilt angle (

The beam is tilted in the opposite direction under the condition of the displacement distance of the jet on the nozzle channel mouth), until a radiation reflection with the same reflection intensity can also be determined on the opposite nozzle channel edge 31, and then performed at a half-tilt angle Re-tilt movement. The focal point then lies in a plane containing the nozzle channel axis 32 . For alignment at the position of the channel axis 32 , another similar adjustment of the beam axis is then carried out perpendicular to the original direction of inclination.

The white light source 53 can be omitted if the deflection mirror 21 is made slightly transparent (approximately 2%) to the radiation of the laser source 6 . Even in this case, the telescope and the glass plate 57 must be designed for the laser radiation and must have a reflective coating. The camera 55 must be equipped with a chip sensitive to laser radiation. In the event of a calibration error, the laser radiation is reflected by the nozzle edge and its surrounding area. The reflected laser radiation is then observed via the telescopic camera 55 and simultaneously regulated via the aforementioned adjusting device 19 and beam expander 11 . To avoid damage to the nozzle channels and nozzle surfaces, corrections are made with reduced laser power. Since the properties of the laser beam can change at high laser beam intensities compared to the properties at lower powers, the deflection mirror 21 and, if necessary, the beam expander 11 are initially adjusted with increasing laser power. .

To check the centering, the output lens of the beam expander 11 can be adjusted such that the diameter of the beam beam of the laser beam 13 is increased until the nozzle channel edge 31 (ie the nozzle channel opening 28 ) is illuminated uniformly. . Center alignment can only be achieved under uniform lighting conditions. The output lens of the beam expander 11 is then moved in the opposite direction until a uniform illumination of the edge of the nozzle opening occurs again. The position between the two adjustments is now in the nozzle channel inlet plane the adjustment required to ensure optimum focusing, so that the focused jet is symmetrical to the nozzle channel axis 32 .

In the case of Nd:YAG lasers, water can be used as liquid for the liquid jet. Water absorbs very little radiation at 1.06 microns. The above-mentioned small absorption is still sufficient to meet the requirement of forming a thermal lens before the nozzle inlet. Therefore, for some applications it is preferable to use silicone oils, especially those selected from the polymethylsiloxane family.

If water is used as the liquid, it is necessary to use laser radiation which absorbs less than 0.2 cm ^-1, preferably less than 0.15 cm1. If radiation with higher absorption is used, too much radiation power is absorbed in the liquid jet. In the case of high radiation absorption in liquids, vaporization effects are possible. Thus, even under flow-optimized conditions, for example, the formation of thermal lenses in the focal point in front of the nozzle inlet is not sufficiently suppressed. When water is used as the liquid, low absorption values are obtained under radiation conditions in the wavelength range of 150nm (nanometer) to 1100nm, preferably 190nm to 920nm and between 1040nm and 1080nm (in the range around 1000nm There is an absorption peak inside). Therefore, it is preferable to use diode lasers, YAG-lasers, frequency-doubled YAG-lasers, excimer lasers and copper vapor lasers. YAG lasers have the advantage, for example, that well-developed devices of this type are available on the market; they can also achieve high average powers.

Radiation can be continuous or pulsed. In the case of pulsating radiation, the liquid cools the cutting edge produced in the manner described above. At the same time, the heat generated by the radiation absorbed in the liquid jet is also dissipated. Thus, due to the high heat capacity of water, high radiant power can be pulsatingly incorporated into the liquid jet. In the case of Nd:YAG lasers and water as liquid, pulse powers of up to 20 kW with a pulse length of 20 to 500 μs (microseconds), an average power of 600 W and a pulse rate of up to 5 kHz can be incorporated.

However, it is also possible to use optically switched Nd:YAG lasers (Q-switched YAG) with a pulse length of typically 50 to 250 ns (nanoseconds), an average power of 20 to 120 W and a pulse rate of up to 60 kHz. Mode-coupled lasers with pulse lengths in the femtosecond (10 ⁻¹⁵ s) range can also be used.

Continuous radiation lasers (eg cw YAG) can also be used. In this case, however, the average power is limited by the lack of radiative interruption. This makes it possible to combine only about 700 W of the radiation power of an Nd:YAG laser into an 80 μm thick water jet. At higher laser power densities, the water is heated to such an extent by radiation absorption that vaporization starts beyond a certain jet length. This would then cause the water jet to start breaking up into loose droplets; perfect radiation guidance would no longer be possible.

The aforementioned nozzle block 27 is made of quartz or diamond, but can also be made of a material that is transparent to laser radiation. The nozzle outlet and the walls of the adjoining nozzle seat 33 are conical and have a reflective coating for the laser radiation. It is also possible to manufacture the nozzle block 27 from a material which strongly reflects laser radiation. For a laser radiation of 1.06 m, nozzle blocks made of gold can be used. Since pure gold is too soft, trace amounts of copper and silver must be doped in order to achieve a hardness of 150 to 225 HV (Vickers hardness).

Claims (14)

1. The material processing method of the workpiece (45) that adopts the laser beam incorporated in the liquid jet (25), is characterized in that: must meet three requirements together here, namely the first, the laser beam is focused to form the liquid jet On the channel inlet plane (30) of the nozzle channel (29) with a ray focusing cone (38); second, the liquid that will use the nozzle channel (29) to form the liquid jet (25) does not flow swirl and Delivery without tangential shunting; third, delivery of the liquid fast-flowing, free of stagnation chambers to the nozzle channel opening (28) and free of stagnation chambers in and immediately surrounding the focusing cone (38) , for which the flow is divided into a plurality of identical, radially inflowing, angularly equidistant subflows (37). 2. Method according to claim 1, characterized in that, below the workpiece (45), the presence of the liquid jet (25) on the extended position of the nozzle channel axis (32) is detected, and only when the detection Only move the workpiece (45) and/or change the laser power incorporated under certain conditions. 3. The method according to claim 1, characterized in that the nozzle channel opening (28) and its edge regions are visualized optically, the laser beam that is focused on the channel inlet plane and does not have material processing energy The beam axis or the beam axis of an illuminating beam that extends in congruent overlap with the laser beam is moved parallel to the nozzle axis (32) until a first nozzle edge with the first nozzle opening (28) can be determined until the reflection of the first radiation of a reflection intensity, followed by a displacement of the beam axis in the opposite movement direction under the condition of measuring a displacement distance, up to the second nozzle at the nozzle channel opening (28) opposite the edge of the first nozzle As far as the edge region can determine a second radiation reflection with the same reflection intensity as the first reflection intensity, the beam axis is then shifted in the opposite direction again by half the displacement distance, then perpendicular to the above-mentioned direction of movement and also parallel to the nozzle axis (32) Another similar adjustment of the beam axis is performed so that the laser beam is centered on the nozzle channel opening (28) of the nozzle channel (29) forming the liquid jet. 4. A material processing device for processing workpieces (45), having a laser radiation source (6) and a liquid jet (25) formed by means of a nozzle channel (29) of a nozzle block (27), utilizing an optical focusing device ( 23) A focusing cone (38) can be produced and the laser beam of the laser radiation source (6) can be incorporated into the liquid jet (25) and guided in the liquid jet, characterized in that the nozzle block is opposite to the nozzle channel (29) has a nozzle channel inlet plane (30), a nozzle channel mouth (28) of the nozzle channel (29) is in this plane, the design and Arranged so that the focal point of the laser beam focused by the focusing unit is in the nozzle channel inlet plane (30), and there are a plurality of identical and angularly equidistant liquid supply lines (36) extending radially with respect to the nozzle axis (32) . (28) and the region of the nozzle channel (29) also does not allow any liquid swirl to occur. 5. The material processing device according to claim 4, characterized in that: a disc-shaped antechamber (36) surrounding the nozzle channel opening (28) has a plurality of liquid supply lines (37) that flow radially into it , where the height of the front chamber (36) is equivalent to the radius of the nozzle channel, so that even in the front area of the nozzle channel opening (28) in order to avoid a liquid stagnation chamber, the liquid has a flow velocity that is only slightly lower than that in the nozzle channel (29), the side walls of the liquid supply line (37) just merge into each other at the confluence of the antechamber (36), and the liquid supply line (37) is arranged in a radial form, wherein the adjacent The axes of the liquid supply lines (37) all have the same central angle, so that the liquid flowing to the nozzle channel opening (28) will not have a tangential split according to the nozzle channel axis (32). 6. The device according to claim 4, characterized in that: a nozzle channel length as short as possible, wherein the nozzle channel outlet (26) has a conically designed outlet section whose opening angle is greater than one Splitting of the incorporated laser beam arising from instabilities in the liquid jet (25). 7. The device as claimed in claim 4, characterized in that an as short as possible nozzle channel length is less than twice the nozzle diameter. 8. The device as claimed in claim 6, characterized in that the opening angle of the outlet section of the nozzle channel outlet (26) is greater than 60° for laser radiation with a wavelength in the range from 150 nm to 1100 nm. 9. The device as claimed in claim 4, characterized in that a conically shaped (35) nozzle outlet (26) of the nozzle channel (29) is coated reflectively against the laser radiation. 10. The device as claimed in claim 4, characterized in that the nozzle block (27) is made of quartz if the laser radiation source used has a wavelength in the range of 150 nm to 1100 nm. 11. The device as claimed in claim 4, characterized in that the nozzle block (27) is made of a material that strongly reflects laser radiation. 12. The device according to claim 4, characterized in that: a force sensor (47) is arranged on the extension line of the nozzle channel axis (32) below the nozzle outlet, and the workpiece (45) to be processed can be placed on the On the sensor, the sensor (47) is so designed that it can send a signal when the liquid jet (25) occurs, whereby it can be determined: when the workpiece (45) is guided by the liquid jet (25) of the laser beam Approximately penetrating in the direction of the axis of the nozzle channel. 13. Device according to claim 4, characterized in that there is a liquid supply regulating device, which can eliminate liquid pressure fluctuations in the liquid delivered to the nozzle inlet, and preferably also degas the liquid, especially It is capable of removing particulate matter from liquids. 14. The device according to claim 4, characterized in that: there is an observation device (21, 57, 56, 55) for observing the nozzle channel opening (28) and its surrounding area; there is also a displacement device ( 19, 21) for moving the focused laser beam (13) falling on the nozzle opening (28) in such a way that it is exactly in the center of the nozzle opening (28).

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