JP2022548343A - Method and apparatus for drilling components - Google Patents

Abstract

Kind Code: A1 A method for drilling a component made of metallic material and a component made of stacked metallic and dielectric materials is described, and includes a hole axis, a hole wall, and a hole depth as the hole progresses. The spatial distribution of the Poynting vector assigned to the laser radiation is adjusted differently in the overlap region of the hole to be generated and in the edge region of the hole to be created, where the hole bottoms are assigned progressively in increments. , the overlap region is defined as the region irradiated with a high energy flux density of laser radiation in the case of single-pulse drilling, the edge region is located outside the overlap region and the energy in the overlap region during drilling is It is defined as the area irradiated with a low energy flux density of laser radiation that is lower than the flux density. A corresponding device is also described. [Selection drawing] Fig. 1

Description

The present invention relates to a method for perforating components made of metallic material and components made of stacked metallic and dielectric materials by means of laser radiation. Furthermore, the invention relates to a device with which the corresponding method can be implemented.

Laser radiation is used in particular for the removal and drilling of metallic materials and composite materials consisting of dielectric (eg ceramic) and metallic layers, called melt drilling. Especially for applications in automotive engineering, aeronautical engineering, medical engineering (processing of thin or thick sheets) and energy engineering (processing of so-called thick sheets), high removal rates are desired for making holes and therefore high production It is desirable to have a high quality and a good conicity K=r _B,top /r _B,bot and avoidance of recasting. The hole conicity K=r _B,top /r _B,bot is defined as the ratio of the hole radius r _B,top at the hole entrance and the hole radius r _B,bot at the hole exit. Hole geometry (eg cylindrical, conical) and hole wall morphology (eg solidified melt/recast) are key indicators that need to be avoided.

Various requirements must be met in melt drilling. It includes reproducible diameter of the hole, defined conicity of the hole, defined conicity when drilling multilayer systems, no loss of adhesion strength or shear strength of the coating, solidified melting No build-up (recast) of material on the hole wall, no flash formation at the hole exit, defined evacuation of the melt, large curvature of the exit edge in the region of the hole opening, etc.

Known techniques for drilling with laser radiation are differentiated based on the primary mechanism for removing material from the forming hole. Removal can take place primarily by melt discharge or primarily by vaporized material discharge. The groups of drilling techniques in which melt ejection is predominantly performed include single pulse drilling (drilling with a single pulse), percussion drilling (with a fixed position of the beam axis of the radiation relative to the workpiece). and trepanning drilling (multiple pulses while moving the position of the beam axis of the radiation relative to the workpiece). Each drilling technique has both advantages and disadvantages.

Percussion drilling is a technique in which a laser beam is irradiated without changing the irradiated position, thereby creating a hole or perforation at this irradiated position. Percussion drilling requires only a short processing time because it does not move the irradiation position of the laser beam.

Single pulse drilling and percussion drilling, which have the advantage of high removal rates (high productivity), have the disadvantage that the maximum achievable hole diameter, which is limited by the beam diameter of the laser radiation, is too small and imperfect drilling. Poor hole quality due to poor melt discharge and deposits of solidified melt on the hole walls and/or hole entrance and hole exit, and low accuracy with respect to hole diameter.

In so-called trepanning drilling, percussion holes are first drilled in the material of the component and then holes of defined radius are drilled out. Drilling by trepanning is a technique in which the laser light is moved along the circumference of the hole to be formed, the laser light having a spot diameter or beam diameter that is smaller than the hole or perforation to be made. , thereby forming an opening along the circumference and thus creating a hole or perforation. In the trepanning process, since the laser beam is irradiated along the circumference of the hole to be formed, the shape accuracy of the hole is improved.

Trepanning drilling provides hole diameters larger than the beam diameter of the applied radiation (hole diameter = 1.2 x spot diameter) while also improving hole wall quality compared to single pulse drilling and to percussion drilling diameter) can be realized. However, trepanning drilling has the disadvantage that a large portion of the applied radiation penetrates the component through the existing holes unused, requiring long drilling times.

For single-pulse drilling and percussion drilling, measures are known which aim at the most complete possible evacuation of the melt from the hole in order to achieve a defined and often cylindrical shape of the hole. . Among such measures is increasing the spatial average or maximum value of the intensity or energy flux density of the applied laser beam as the depth of the hole increases (power per area W[/m ² ] in units of energy per volume multiplied by velocity [(J/m ³ )(m/s)]), and temporally modulating the intensity by a number of single pulses during the entire drilling time. It is to do (percussion).

DE 10 2004 014 820 (corresponding to US 2007/193986) describes a metallic material and a laminated metallic material and a laminated metallic material having at least one ceramic layer, an aspect A method for fabricating high ratio holes is described. It becomes clear from this document that for percussion drilling the hole-producing radiation is directed with respect to the direction of the radiation in the direction opposite to the propagation of the radiation, i. It can be designed to achieve a complete evacuation of the melt from the hole up to the maximum hole depth with a low build-up of .

Industrial applications of percussion drilling, irrespective of the state of the art, have layer thicknesses of adhering solidified melt, typically greater than 100 μm, and thereby have low accuracy of hole geometry, Only if the quality deficiencies of the holes that still occur, i.e. the imperfect melt discharge, do not limit the functionality of the product.

In addition to percussion drilling and trepanning drilling, helical drilling and laser erosion are also included in drilling techniques that primarily involve evaporation.

Spiral drilling additionally rotates the radiation about the beam axis to trepanning drilling, thereby compensating for deviations of the spatial distribution of the laser radiation from circular symmetry on average over time. The approximation to the required geometry and the required hole quality can currently be achieved only by helical drilling or by a sequential combination of percussion drilling and helical drilling.

DE 101 44 008 A1 describes a method for producing holes in a workpiece using a laser beam. In a first step, a hole is drilled with a first diameter smaller than the final diameter to be achieved, and in a second step, or even a further step, the hole is enlarged to the diameter to be achieved. be. Thus, the percussion hole, which is created primarily by melt ejection, is expanded to the desired diameter by removing material as a vapor in a second method step, so that the solidified melt residue is removed from the hole wall. Almost nothing remains. Such drilling techniques have the drawback of too long drilling times or, as a consequence, too low productivity.

Furthermore, in the known method the melt ejection is produced by vaporization of the material and is therefore controlled only through the intensity of the laser radiation, which requires precise control of the hole diameter and avoidance of melt deposits, also called recasting. not allow. Such a method then requires a second method step for smoothing the hole walls by evaporative removal of material, as indicated in the above-mentioned DE 101 44 008 A1. .

As also described in DE 101 44 008 A1, the prior art, which is primarily concerned with drilling with melt ejection, is characterized by a rough and crack-prone layer of resolidified melt (recast). It teaches that it can occur in the hole walls, leading to deviations from the desired geometry of the hole. According to DE 101 44 008 A1, therefore, recasting and deviations from the required hole diameter are eliminated by post-machining and the hole walls are smoothed by removal by evaporation.

US Pat. No. 5,837,964 describes a laser machining method in which percussion drilling and trepanning are applied sequentially in time. This document describes aspect ratios greater than 10 and sequential processing in time, first percussion drilling and then trepanning.

DE 102004014820 DE 10144008 A1 U.S. Pat. No. 5,837,964

Given the prior art described above, the object of the present invention is to obviate at least some of the drawbacks described above with reference to the prior art, in particular to reduce the required machining time and for that reason to To provide a method for perforating a metallic material and a material laminated from metallic and dielectric materials without lowering accuracy. According to a further task, it is also intended to provide a device with which this method can be implemented.

This problem is solved for a method by a method having the features of independent claim 1 and for a device by an apparatus having the features of independent claim 12 . Advantageous embodiments of the method and device emerge from the dependent claims.

By means of the method of the invention, components made of metallic materials and components made of laminated metallic and dielectric materials are mainly melted by laser radiation by single pulse/percussion drilling and by trepanning drilling. Perforated by ejection. Single pulse drilling is considered a non-pulsing method. This is because the energy flux density of the laser radiation is not interrupted in time until the drilling is completed or the through drilling is performed. Trepanning drilling can be performed not only pulsed, but also unpulsed without temporal interruptions (pulse pauses). Single pulse drilling/percussion drilling and trepanning drilling are performed simultaneously in time in the present invention.

having a beam axis (B _A ) (beam axis) and a beam diameter (D _S ), the direction of which is different from that of the beam axis (B _A ) at a position lateral to the beam axis and of local radiation propagation; of the Poynting vector (<S>) assigned to the laser radiation (LS), defined as the vector that indicates the direction and is the energy flux density of the radiation whose value is defined as energy per volume multiplied by the speed of light. The spatial distribution is the holes to be generated (H) to which the hole axis (H _a ), the hole wall (H _w ), and the hole bottom (H _b ), which progresses with the progress of the hole depth, are assigned. , and the edge region R of the hole to be generated are adjusted differently. The energy flux density with the unit [Jms ⁻¹ m ⁻³ ] (energy velocity/volume, Jms ⁻¹ m ⁻³ =Wm ⁻² ) is also called the intensity of the laser radiation.

By means of the method of the invention, a high energy flux density of the radiation is adjusted in the overlap area (O) and a low energy flux density in the edge area. Such a spatial division of the energy flux density of the radiation, viewed in time, between high-speed through-drilling in the overlap region (O) and high-quality removal of the hole wall in the edge region. Evoke parallel applications. The method according to the invention combines the advantages of known drilling methods, namely the high productivity of single pulse drilling or percussion drilling and the high quality of trepanning drilling.

A combination of known drilling methods in which the advantages of both methods are achieved requires the observance of intervals containing maximum and minimum values for the intensity of the laser radiation, the maximum and minimum values to be observed being , both in the overlap region (O) and in the edge region R are of different sizes. According to the invention, the adjustment of the intensity of the laser radiation in two different intervals is achieved by applying pulsed laser radiation with a moving laser beam axis, the movement of the laser beam axis for each pulse of laser radiation. and an outer edge region R not illuminated by each pulse. However, the adjustment according to the invention of the two different intervals of the intensity of the laser radiation can also be achieved by suitable beamforming without movement of the laser beam axis.

The overlap area is defined as the area illuminated by each pulse of laser radiation. The edge region is defined as the region located outside the overlap region and inside the laser beam radius.

As regards the method, the maximum value A _max of the aspect ratio A, defined as the ratio of the hole length to the hole diameter, has the value A _max =10 with A=d/(2r _B,top ), where d is The material thickness of the material to be drilled through, in the case of a hole (H) that is perpendicular to the surface or top of the material, or in the case of a hole axis that is inclined relative to the top of the material. is the hole length and r _B,top is the hole radius of the hole (H) at the hole entrance defined as the radius measured in the direction perpendicular to the hole axis (H _a ).

Such a limit A<A _max for the aspect ratio is important because for relatively large aspect ratios A, greater than 10, the hole wall (H _W ) is directly irradiated at point A, according to the invention. This is because, in addition to the radiation adjusted accordingly, the radiation reflected by the hole wall (H _W ) at another location B also contributes to the elimination at location A. By reflection of the hole wall (H _w ) and multiple irradiations, the adjustment according to the invention of the laser radiation (LS) at the hole wall (H _w ) is changed for the reflected radiation to carry out the method. will not be possible.

It is necessary in the prior art, for example as described in DE 10 2004 014 820 for single-pulse drilling or percussion drilling, to remove completely from the hole produced the melt in the direction opposite to the incident laser radiation. No measures are required to produce the hole-forming radiation so as to discharge into the hole and eliminate solidified melt deposits on the hole walls.

A further advantage of the method according to the invention can be found in that no subsequent trepanning drilling is required for subsequent removal of eg solidified melt deposits on the hole walls (H _w ).

One main measure of the method according to the invention can also be found in that the hole to be created (H) is divided into a central or overlapping area (O) and a rim area (R). The spatial distribution of the radiation (LS) perpendicular to the hole axis (H _a ) of the hole (H) to be realized is adjusted differently in the overlap region (O) and edge region (R) respectively. .

The adjustment of the direction of the Poynting vector <S> assigned to the laser radiation (LS) in the edge region (R) of the hole (H) to be realized is done by adjusting the focus position and the Rayleigh length of the laser radiation (LS). can be done.

For the method according to the invention, the energy flux density of the radiation in the edge region of the hole to be produced must be measured and adjusted very precisely. This is because at very small values for the energy flux density the removal already takes place. The minimum required energy flux density for ablation, according to the invention, is W cm ⁻² for pulse times longer than 1 ns, or J cm ⁻² (10 ⁻⁴ Wm ⁻² or equivalent to Jm ⁻² ), and this threshold is defined as all other hole-related parameters known to characterize the material to be drilled (melting temperature , heat capacity, thermal conductivity, etc.), with typical values of 10 ⁴ to 10 ⁵ W·cm ⁻² or 1 to 10 J·cm ⁻² for metallic materials.

Measurements with commercially available instruments that have a limited area for the energy flux density to be measured and are not capable of simultaneously detecting arbitrarily large differences in energy flux density are possible, e.g. Only if the high intensity areas of the beam are faded out and thus the outer areas of the laser beam can be measured with high resolution, the adjustment must be controlled by measurement.

During drilling the laser radiation (LS) is preferably guided such that its beam axis (B _A ) makes a movement along a closed trajectory curve (C) which is to be traversed at least once. Half the beam diameter (D _S ) is then chosen to be at least as large as half the diameter (D _C ) of the trajectory curve (C). The movement of the laser radiation (LS) during drilling is done using a scanner, for example.

In yet another approach, the energy flux densities of the radiation (LS) in the overlap region (O) and the edge region (R) of the hole (H) to be created are adjusted differently with temporal averages. be able to. It means that the laser radiation is pulsed, during which the beam axis (B _A ) passes through a closed trajectory curve (C), the time between two consecutive pulses (pulse pause) is changed, The trajectory velocity v _C is changed with a mean value over time.

Aspect In order to cause the maximum value A _max according to the invention for the ratio to be enlarged, the Poynting vector (<S>) in the edge region (R) of the hole (H) is defined by the hole (R) to be created is adjusted with the directional component pointing toward the hole wall (H _W ) of . This measure increases the absorption of the incident radiation (LS) and avoids reflection of the radiation (LS) to relatively deep regions of the hole wall (H _w ) of the hole (H) to be formed. , or at least reduced to such an extent that the threshold for removal is not exceeded and unmanageable removal does not occur.

The critical fluence F _th , ie the threshold for pulse times shorter than 10 picoseconds, is reached or even below during hole formation or after a finite number of cycles of passage. This is because the hole wall becomes progressively steeper with each pulse, so that the fluence of radiation incident on the hole wall impinges on progressively wider surfaces or areas of the hole wall. When the critical fluence F _th is reached or below it, removal is no longer possible and the asymptotic geometry of the hole is achieved. This is the definition and measurement rule for the value of the critical fluence F _th determined from a comparison of simulations and experiments. The geometry of the hole approaches the final or asymptotic shape (also called the final shape) and no further removal is possible. An approximation to asymptote always means that the perforation result when asymptotic is reached becomes independent of irradiation time, or only weakly dependent in the case of approximation, and is therefore reproducible. is assumed.

In order to ensure a high reproducibility of the geometry of the holes (H), it is preferable to ensure that the hole walls (H _w ) reach asymptotics. To that end, for example, multiple holes (test holes) are produced with increasing number of pulses (pulsed laser radiation) or with increasing irradiation time (cw laser radiation), with unnecessarily long laser radiation (LS). , it is observed that the hole (H) does not progress any further. The hole diameter achieved is experimentally determined by making cross-sectional grinds. Asymptoticity is achieved when the experimentally determined hole shape or hole diameter from cross-sectional polishing ceases to change. If the asymptotic attainment of the hole wall (H _W ) is guaranteed, the other holes are also fabricated with exceptionally high reproducibility or technically negligible mutual errors (less than a few micrometers). be able to.

The asymptotic shape or asymptoticity of a hole occurs after a certain number of pulses of laser radiation (pulsed laser radiation) or after a certain irradiation time (cw laser radiation) and all subsequent pulses or It means a hole shape that is no longer changed by the irradiation, which is also called removal stop. The number of pulses of laser radiation at which the asymptotic property holds or is approximated depends on the values of the material, beam and method parameters. An asymptotic approximation therefore means that the achieved hole shape will not change as the irradiation time progresses, or the resulting hole shape will change only slightly as the irradiation time progresses, and It is assumed that the resulting hole shape is reproducible, thus arriving at the final shape.

According to one approach to the method, reaching the final shape of the hole is defined by the adjustment of the laser radiation (LS) with respect to the edge region (R), and it takes less than 1 ns for reaching the final shape of the hole (H). A number with a magnitude of W·cm ⁻² for pulse times longer than 10 picoseconds, or J·cm ⁻² (equivalent to 10 ⁻⁴ W·m ⁻² or J·m ⁻² ) for pulse times shorter than 10 picoseconds. A threshold value defined as 10 ⁴ to 10 ⁵ W·cm ⁻ for metallic materials is defined and substitutes for all other hole-related parameters known to characterize the material to be drilled. It takes typical values of ² or 1 to 10 J·cm ⁻² .

As the drilling time progresses, the hole wall becomes progressively steeper, so that progressively wider partial surfaces of the hole wall (H _W ) are impinged by increasingly increasing radiation fractions, such that , the fluence (F) of the radiation incident on the hole wall (H _W ) becomes lower. In this way, the hole shape is reproducibly and highly accurately approximated to the final shape that cannot be removed any more.

For pulse durations shorter than 10 picoseconds, or durations of interaction between the material and the laser radiation, the laser radiation only stores the absorbed energy in the material's free electrons, leaving the material's atoms to be irradiated significantly No heating. Instead of the energy flux density [J·m ⁻² s ⁻¹ ], the fluence (F) [J·m ⁻² ] is defined as the integral of the energy flux density over time, the fluence irradiating the material per area. It is defined as the fraction of the energy of laser radiation (radiant energy) and has the SI unit J·m ⁻² .

The radiant energy per area irradiated by the material of the component can also be called the fluence (F) with F=I·Δt, where the energy flux density is also called the intensity I, and Δt is the time the component is irradiated. show.

Below a threshold for fluence (F) (critical fluence F _th ), removal is no longer possible and an asymptotic geometry of the hole is achieved. That is, the geometry of the hole approaches the final or asymptotic shape and no more can be removed. For high reproducibility of the hole geometry, therefore, as already explained above, reaching asymptotics must be ensured.

When the material is drilled through, the hole base of the hole is open and part of the laser radiation passes through the hole and is not absorbed by the material to be drilled. The hole base (H _b ) is then defined as the edge of the forming hole (H) that progresses during drilling. In the hole (H) which is open at the bottom of the hole, the melt is accelerated less strongly from the periphery of the opening, does not exit the hole completely and solidifies on the hole wall. In order to avoid that the melt to be discharged during drilling solidifies on the hole wall, one preferred strategy for drilling with pulsed laser radiation is to use , the melt is ejected from the hole (H) in a direction opposite to the direction of propagation of the laser radiation (LS) before the through-drilling of the overlap region (O). This is achieved by adjusting the energy flux density of the laser radiation in the overlap region (O) such that the hole base does not reach the material thickness and lead to through-drilling. In this way, as little residual volume as possible remains in the hole, at least partly as undesired recast, which still has to be discharged in order to reach the final shape of the hole.

The method allows for the ejection of the melt from the formed bore based solely on evaporation pressure without the use of gas nozzles. The energy flux density and pulse time in the overlap region, i.e., the region irradiated with each pulse of laser radiation, is reduced to is adjusted to reach It should typically be less than 100 μm for non-rotating components that cannot be solidified and ejected at the hole wall, and typically less than 50 μm for rotating and accelerated components. The effect of a small recast thickness can be confirmed by measuring the thickness of the melt pile. The _intensity and pulse time of the applied radiation are the minimum of It is adapted so that only a limited residual volume needs to be evacuated. At this point, a very small residual volume of material still to be expelled is melted and expelled from the hole partly downwards and partly upwards along the hole wall by the evaporation pressure, There it is further partially solidified to form a recast.

It should not fall below the minimum energy flux density and should not exceed the maximum energy flux density. The minimum value is determined by no through-drilling, defined as the hole base not yet open on the underside of the component, and the maximum value dramatically increases the drilling time to reach the through-drilling. determined by The dramatic increase means that for energy flux densities slightly below the maximum value, short drilling times are sufficient to drill through the material, at which the drilling velocity _vP takes high values, typically takes a value larger than 1 ms ⁻¹ , and for energy flux densities slightly higher than the maximum value, a long drilling time is required until through-drilling, and the drilling speed v _P takes a small value, typically takes a value smaller than 10 ⁻² ms ⁻¹ .

In addition, too low an energy flux density of the laser radiation is not sufficient to eject the melt from the hole through its entire depth, and too high an intensity of the laser radiation causes too dense a metal vapor, which causes the laser It absorbs the radiation considerably, thus lowering the drilling speed v _P .

With respect to the method, a circular hole, 8 in cross-section, is obtained by adjusting the incremental angle (Alpha), defined as the angle by which the beam axis (B _A ) of the laser radiation rotates about the hole axis (H _a ). Letter-shaped holes, slots, or three-hole holes, or star-shaped holes can be produced. In the prior art, the production of non-circular hole cross-sections requires a beam diameter of the laser radiation smaller than the minimum cross-section of the hole, and the hole contour to be generated has to be followed along the trajectory curve. The smallest cross-sectional shape achievable by application of methods based on the prior art is, for example, that the x-shaped area in the center of a figure-eight profile is at least as large as the beam diameter when the profile is followed. Yes, ie larger than with the application of the method according to the invention. This is because according to the method of the invention, the x-shaped area of the figure-eight contour is illuminated only by the overlapping region of the laser beam diameters.

The method of the present invention produces a figure-eight hole with an increment angle of 180 degrees between two successive pulses until the laser radiation is pulsed, at which time a figure-eight hole shape is achieved. It is produced by adjusting the increment angle and pulse time such that the pulses are repeated on reaching 0 and 180 degrees. For slot formation, the increment angle is 180 degrees between two consecutive pulses, and the pulses are repeated when 0 and 180 degrees are reached, also in 180 degree increments. The angle and pulse time are adjusted, with the overlap area sized to produce a slot. A 3-hole hole is, for example, a hole having 3 holes with an angular spacing of 120 degrees, and is generated by adjusting the incremental angle to 120 degrees, until a 3-hole hole is formed, 0 degrees , 120 degrees, and 240 degrees, the pulses are repeated. Star-shaped holes are produced based on the method of the present invention at 0 degrees, 360 ^* 1/n degrees, 360 ^* 2/n degrees, . . . 360 ^* (n−1)/(n) where the pulse is repeated when reaching degrees, where n is a natural number and 360/n is the natural number until the star hole is achieved. is.

The main advantages and peculiarities of the holes that can be produced by the method of the invention, as well as the special applications and fields of application that arise from them, can be summarized as follows. The diameter of the holes to be produced by the method according to the invention increases with irradiation time and tends to reach an asymptotic value. When approximating an asymptotic value for the hole diameter, the per-pulse ablation or drilling rate v _P tends to zero and the hole diameter is reproducible.

In this regard, it should be noted that in the case of drilling using a gas jet to discharge the melt, the minimum diameter of the resulting hole relative to the hole depth is a measure of the hole geometry, which is the gas charge. limit the volumetric flow rate of

The total through-flow volume of a fuel filter or the like is the sum of the through-flow volumes of the individual holes. Cooling of the turbine is achieved by means of holes whose diameter and expansion (conicity) determine the cooling effect. The manufacture of holes in fuel filters and turbine components is therefore a particularly important field of application for the method according to the invention.

The flow behavior when a gas or liquid is discharged from a hole is determined, inter alia, by the angle of the hole wall with respect to the material surface and the expansion of the hole, ie the conicity of the hole. Adherence to a predefined conicity is particularly important for the distribution of cooling gases on material surfaces, for example to protect turbine components. The method of the present invention allows such conicity to be adjusted in a very defined manner, which means that the Poynting vector (<S>) in the edge region (R) of the hole (H) is equal to the hole to be achieved. By having a directional component that points towards the hole wall (H _W ) of (H) and varies monotonically with hole depth. Since the radiation absorption, and thus the drilling velocity v _p , increases with increasing directional component pointing towards the hole wall (H _W ), the hole diameter also increases proportionally with this directional component.

The shape of the cylindrical or conical hole is a prerequisite for laminar flow of liquids and gases through the hole. The diameter of the holes in multilayer systems consisting of a base material, an adhesion layer and a thermal insulation layer, as is the case especially in turbine components, should be adjustable independently of the respective material layer to be drilled through during drilling. which must result in smooth hole walls and evenly expanding or decreasing hole diameters with increasing hole depth, regardless of the material layer to be drilled through. occurs. This is made possible, according to the method of the invention, by first through-perforating the insulating layer, which requires a relatively high energy flux density for through-perforation or has a relatively high value for the threshold fluence, The drilling time is further removed by a lower energy flux density or a lower threshold fluence value when the hole in the insulation layer reaches its asymptotic shape and upon subsequent drilling in deeper material layers. selected not to be

Yet another surprising property of the method according to the invention is that when drilling multilayer systems (insulating layer ceramic and base layer metal) with very different properties for laser radiation absorption and heat conduction, the hole depth It can be seen in that a defined conicity is achievable throughout. Surprisingly, the layer to be drilled first has negligible influence on the drilling process and thus the hole shape. This can be understood as a consequence of the melt flow flowing through and overlying the ceramic layer that is drilled first, so that the absorption of laser radiation and the heat conduction are of the same magnitude for the insulating layer and the metallic base layer. , thus producing a smooth hole wall. It is thus important that the method according to the invention has a melt discharge opposite the beam direction from the start of drilling to the point of through-penetration. Since the hole occurs in the central region, the region of the hole which suffers from quality deficiencies (here shape errors due to different material properties) etc. is removed in the subsequent steps of drilling and therefore does not contribute to the quality of the hole. The melt of the metal layer lying deeper is driven towards and covers the e.g. , leading to dominance of heat from the overlying melt.

No reduction in adhesion strength and shear strength of the coating is observed. When perforating multilayer systems, the adhesion between the layers must not be compromised in the area of the holes. For example, if the thermal insulation layer of a turbine component is damaged, the layer of the component, which is subjected to high thermal and mechanical loads during operation, can delaminate from the base material and the protection provided by the thermal insulation layer is no longer guaranteed. The bond between each layer is thermally loaded during drilling by the melt flowing along the hole wall in the direction opposite to the beam direction, with each layer melting the melt flowing by during each pulse. The pulse pause between two consecutive pulses is the thermal diffusion, because the thermal expansion of the different layers causes a thermodynamic effect that shears the layers with different intensities. The length must be chosen such that no heat build-up occurs which enhances the shear loading action, which can reduce the heating again. Note that the heat penetration depth (scaled by the thickness of the insulation layer) into the insulation layer must be kept less than 1, otherwise The shear action becomes too strong as shown in the graph of FIG. 4 of the drawings. In this figure, the penetration depth of heat into the heat insulating layer and the temperature at the hole wall of the heat insulating layer after heating are indicated by time tp and pulse pause tpause. This is possible according to the method of the invention by selecting the pulse pause tpause as a multiple of the pulse time tp, where the temperature T is the temperature scaled according to the relationship T=Ta+(Tm-Ta)Ts Calculated from Ts. Ta represents the ambient temperature, whereas Tm represents the melting temperature. Referring to the graph of FIG. 4, it can be read how the scaled temperature Ts drops during the pulse pause tpause. To achieve cooling from the melt temperature Ts=1 to the tenth part of the melt temperature Tm - the constant curve of FIG. 4 - the pulse pause tpause must be 40 times the pulse time tp.

The method of the invention avoids depositing (recasting) of the solidified melt on the hole walls. A defined hole diameter can only be achieved if irregular deposits of solidified melt on the hole wall do not change the hole geometry, and these deposits influence the drilling progress and the hole geometry. It will also unsystematically affect academic forms. Furthermore, cracks and stresses can develop in the solidified melt, which can lead to damage during operation of the component. For highly loaded components such as turbine blades and fuel filters, avoiding deposits of solidified melt increases their service life.

Burr formation by solidified melt at the hole exit is avoided. This is because with the method, after reaching the asymptotic shape of the hole, a through-drilling hole with a smaller hole diameter than the hole diameter in the edge region is produced in the overlap region. Short drilling times, since the burrs that occur at the hole exit, e.g. Realized. Avoiding flash formation saves post-processing, reduces production time for turbine components and fuel filters, for example, and improves cooling efficiency. This is because flash formation at the hole exit would otherwise reduce the flow resistance of the cooling fluid and thus the cooling efficiency.

Ejection of the melt can be achieved in the direction opposite to the incident laser radiation by means of a pressure gradient based on evaporation of the material of the component at the bottom of the hole, which for small hole diameters is driven externally. is much more efficient in the initiation phase of drilling than the gas jet-based pressure gradient of . The prior art requires an external gas jet to eject the melt. Experience with the method of the present invention has shown that melt evacuation in the overlap region by evaporation-based pressure gradients is sufficient and no external gas jet is required. A large fraction of the melt originating from the overlap region flows out of the hole in a direction opposite to the incident laser radiation, reducing recast on the hole wall. In the manufacture of stents, fuel filters and turbine blades post-processing, also called cleaning, is normally required when material residues (recast) are deposited in the holes during drilling.

A very small radius of curvature can be achieved at the exit edge of the hole. Such small radii of curvature, i.e. sharp edges which ideally correspond to 90 degree or right-angled edges, are achieved by increased absorption of the laser radiation in the hole wall in the vicinity of the entrance edge, which is A directional component that varies with hole depth such that the Poynting vector (<S>) in the edge region (R) of the hole (H) points towards the hole wall (H _w ) of the hole (H) to be achieved by having

The melt that is generated should delaminate (i.e., no flash) from the entry edge while the hole is being produced, and during use of the hole as a nozzle hole, for example, from the exit edge. It is good for the fuel to separate. That is, the separation of the liquid flow at the hole opening (i.e. either at the entry edge where the hole is created or at the underside of the component where the hole bottom opens first) is determined by the curvature of the exit edge. The curvature of the exit edge at the injection nozzle is decisive for fuel separation and complete combustion in the combustion chamber. The entrainment of ambient gas into the holes and separation of the cooling gas flow from the exit of the cooling holes in the turbine blade are also undesirable flow characteristics, the occurrence of which depends on the geometry of the exit edge, which is It is preferably right angled or at least approximately right angled.

The apparatus of the present invention for drilling components made of metallic material and components made of laminated metallic and dielectric materials comprises a laser processing apparatus comprising at least one beam unit for directing laser radiation onto the component. and so that the spot plane, defined as the area of the component illuminated on the upper surface by the laser radiation, moves along the inner circumference area, the position corresponding to the inner circumference of the hole to be made. It has a control unit for controlling the radiation unit and for controlling a portion of the spot plane to produce an overlapping area at any one time within the inner circumferential area of the hole.

Such a laser machining apparatus achieves very good hole shape accuracy and reduces the time required to form a hole compared to conventional methods.

This device utilizes an illuminated area or cross-section of the spot area of the laser radiation impinging on the component that is smaller than the cross-section of the hole to be made.

The laser processing device also emits laser radiation such that the point diameter, which is the diameter of the spot surface, is greater than half the length of the diameter of the hole to be made and less than the length of the diameter of the hole. preferable. This has the advantage that the too high energy flux density of the laser light, which is necessary for through-drilling and which is desirable for rapid through-drilling of the overlap region, is reduced at the edge of the opening, i.e. in the edge region. and a reduction in the energy flux density leads to a smaller ablated volume per pulse, thus improving hole shape accuracy.

The control unit controls the laser beam unit such that the laser radiation extends outwardly from the overlapping area to the area of the opening of the component when viewed radially with respect to the beam axis.

Auxiliary fluid supply units are provided for supplying fluid to the top surface of the component and into the holes formed in the component to improve melt evacuation after the bottom of the hole has been opened.

A laser processing apparatus includes a laser oscillation unit that oscillates laser radiation in a radial direction with respect to a beam axis, and changes the position of a spot surface by reflecting the laser radiation, and at the same time changes the optical path of the laser radiation oscillated by the laser oscillation unit. A galvanometer scanner unit can be used.

Further details and features of the invention will become apparent from the following description of exemplary embodiments with reference to the drawings.

FIG. 1 shows the production of a hole in a component to which the method according to the invention has been applied, in a schematic sectional view in chronological order, in a plane containing the hole axis respectively, before the point at which the hole base is through-drilled. The geometry of the hole wall and hole bottom are shown. FIG. 2 shows, in a schematic cross section, the generation of a hole in a component with the application of the method according to the invention, in a plane containing the hole axis, in chronological sequence, in the geometry of the hole wall at the time of through-drilling. showing the academic shape. FIG. 3 shows, in a schematic cross-section, the generation of a hole in a component applying the method according to the invention, in a plane containing the hole axis respectively, in chronological sequence, in which the hole walls are achieved according to their predefined Figure 3 shows the geometry of the hole wall when it comes to the power-law geometry. FIG. 4 shows a graph representing the temperature at time tp and pulse pause tpause in the hole wall of the thermal insulation layer after heating by the melt passing by. FIG. 5 shows the geometry of the hole to be made in a section perpendicular to the hole axis. FIG. 6A shows a temporal sequence of cross-sectional views corresponding to FIG. 5 of the drilling process for creating a hole by overlapping the emissive proportions of the edge region and overlap region. FIG. 6B shows a temporal sequence of cross-sectional views corresponding to FIG. 5 of the drilling process for creating a hole by overlapping the emissive proportions of the edge region and overlap region. FIG. 6C shows a temporal sequence of cross-sectional views corresponding to FIG. 5 of the drilling process for creating a hole by overlapping the emissive proportions of the edge region and overlap region. FIG. 6D shows a temporal sequence of cross-sectional views corresponding to FIG. 5 of the drilling process for creating a hole by overlapping the emissive proportions of the edge region and overlap region. FIG. 6E shows a temporal sequence of cross-sectional views corresponding to FIG. 5 of the drilling process of creating a hole by overlapping the emissive proportions of the edge region and overlap region. FIG. 7 shows the progression of the through-drilling of the component in a sequence of icons (1) to (4). FIG. 8 shows the trepanning process applied according to the prior art to produce holes in a sequence of images (1) to (4). FIG. 9 shows a schematic structure of a device according to a first embodiment with which the method according to the invention can be implemented. FIG. 10 shows the structure of FIG. 9 with an additional auxiliary gas supply unit. FIG. 11 shows a schematic diagram of a drilling device applicable in the devices of FIGS. 9 and 10 and with an auxiliary gas supply assigned to the drilling device, in a partially cut-away drawing.

Referring now to FIGS. 5 and 6A-6E, components made of metallic materials and components made of laminated metallic and dielectric materials are subjected to single pulse/percussion drilling and pulsed. The method of the present invention for drilling by trepanning drilling with laser radiation or continuous laser radiation will be described.

In order to explain the geometrical situation, firstly FIGS. 1 to 3 are referred to.

FIG. 1 shows a cross-sectional view of a component 1 having a thickness d perpendicular to the top surface 2 before the moment when the hole base _Hb is drilled through. The component 1 consists of a metallic material or of laminated metallic and dielectric materials. In this component 1, _a hole H is already formed with a hole axis Ha extending in the plane of the cross-section, the hole wall being designated _Hw .

The drilling speed is denoted by v _p and represents the motion of the hole bottom surface H _b in the direction of the hole axis H _a . Denoted by R is the edge region, which lies outside the central or overlap region O and is defined as the region irradiated with a relatively low energy flux density of the laser radiation LS during drilling.

The beam axis B _A with the beam direction of the laser radiation moves over a trajectory curve C with direction R _C and repeats this trajectory curve C until the drilling result schematically shown in FIG. 3 is achieved. pass through. The trajectory curve C lies in a plane perpendicular to the beam axis B _A (beam axis).

The hole H in FIG. 1 has not yet penetrated the underside 3 of the component 1 and exhibits a conical cross-sectional shape. This means that the hole H is still bounded by the hole base _Hb to which the diameter D _O of the overlap area O is assigned. The overlap region O is indicated by dashed lines in FIGS. 1-3. Up to this drilling step, the melt is thus accelerated out of the hole base Hb counter to the beam direction of the beam axis _{B A} of the laser radiation LS used and along the hole wall _Hw of the component 1. It is discharged from the hole H on the upper surface 2 . The acceleration effect is caused by the evaporation of material at the bottom of the hole _Hb and the evaporation or ablation pressure acting on the melt of the material in the process.

FIG. 2 shows in dashed lines the cross-sectional shape of the overlapping area O and the geometry of the hole wall _Hw of the hole H when the component 1 is drilled through on the underside 3 . The point at which the component 1 is pierced through is defined by the total width D _O of the overlap region O reaching the bottom surface 3 of the material and the direction of the melt discharge changing, which is also primarily the bottom surface 2 of the component 1. Means that the melt can now be discharged.

FIG. 3 shows the geometry of the hole wall H _w of the hole H when starting from the shape of the hole H as shown in FIG. 2 the hole wall H _w reaches its predefined geometry. The geometry is predefined by a radius r _B,top at the top surface 2 of the component 1 and a radius r _B,bot at the bottom surface 3 of the component 1 . For a conical hole r _B,top =r _B,bot and the hole diameter D _H is constant with hole depth.

FIG. 3 shows that the hole diameter D _O in the overlap region is larger than the hole diameter D _H for the entire hole to be made, which additionally reaches the outer edge of the edge region R, ie the hole wall H _w (dashed line). shown to be small.

In order to produce a hole in the component 1 by means of laser radiation LS, according to the invention both single-pulse/percussion drilling and trepanning drilling are performed simultaneously in time, i.e. both methods In the case of pulsed laser radiation LS they are superimposed by an overlap in the overlap region, or in the case of continuous or non-pulsed laser radiation an inner central region or overlap region O with a high energy flux density and an overlap region O with a low energy flux density. It is superimposed by coordinating with a low outer area or edge area.

A relatively high energy flux density means that a maximum value is not exceeded, beyond which strong absorption of the laser radiation LS occurs in the metal vapor originating from the removed material, resulting in a decreasing energy flux. Drilling time increases dramatically with density. A relatively low energy flux density means that a minimum or threshold value is not exceeded, below which no ablation occurs or ablation arrest occurs.

The beam guiding of the applied laser radiation LS, which is carried out with continuous laser radiation or non-pulsed laser radiation, will now be described with reference to FIGS. 5 and 6A-6E.

6A-6E are cross-sectional views perpendicular to the hole axis H _a of the drilling process corresponding to FIG. Snap iconography) shows the temporal sequence. The beam axis BA passes through a closed trajectory curve _C , and by varying the time between two consecutive pulses (pulse pause) and the trajectory velocity _vc , the temporal average value of the energy flux density in the edge region is Be changed.

Beamforming, which is carried out with continuous or non _- pulsed laser radiation, is such that the laser beam axis BA does not move and the central region O (in the case of pulsed laser radiation, the overlap of the temporally successive individual pulses It is carried out in such a way that the laser radiation LS in the region O) has a relatively high energy flux density below the maximum value and a relatively low energy flux density above the ablation stop threshold in the edge regions.

The hole _H , shown in cross-sectional plan view in FIG. 5, extends through the thickness _d of the component 1 shown in _FIGS . , which results in a cylindrical hole wall H _W through the component 1 .

In FIG. 5, the central area O (also referred to below as the overlapping area _O ), to which the diameter DO is assigned, is hatched. The edge region R extends radially following the central region O as far as the hole wall _Hw .

For the area F _R of this edge region R, the following formula holds: F _R =F _H −F _O =π·D _H /2−π·D _O /2, where F _H represents the cross-sectional area of the hole H. , F _O represents the area of the central/overlap region O.

With reference to FIG. 5 and also with reference to FIGS. 1 to 3, at the start of drilling the hole H shown in FIG. A relatively small drilling progress occurs.

5 and 6A-6E, the upper surface of the component (see also FIGS. 1-3) is illuminated with laser radiation LS, the beam axis of which is denoted B _A and the beam axis B _A It has a beam diameter D _S when viewed perpendicular to . The illuminated area of the upper surface of the component is the cross-sectional area S of the laser radiation LS, also called spot surface S.

The laser radiation LS impinging on the component in the spot plane S is then, according to the invention, guided with its beam axis BA on _a trajectory curve _C , in the example shown on a circular trajectory C, about the hole axis Ha. and this is clearly shown in FIG. 6A. The direction R _C of beam axis guidance along the circular trajectory C (contour C) takes place counterclockwise in the examples shown in FIGS. 6A-6E, but this is not absolutely necessary. Such beam guiding can also be done clockwise.

The following equation holds for the beam diameter D _S .
D _S =D _C +D _O and D _S =D _H /2+D _O /2
D _S = beam diameter of the laser radiation D _O = diameter of the central region O D _H = diameter of the hole H D _C = diameter of the circular trajectory C, also called trajectory curve C

6A then shows the illumination or illumination of the component after two pulses of laser radiation LS, compared to FIG. 5, whereas FIG. 6B shows the illumination or illumination of the component after three pulses of laser radiation LS. 6C shows the irradiation of the component after four pulses of laser radiation and FIG. 6D shows the pulse of radiation after one complete cycle. The edge of the spot area S of each last pulse is illustrated with a thick line.

As is evident from the sequence of FIGS. 6A-6E, the central region O is irradiated with each pulse of laser radiation whose cross-sectional area or spot area is denoted by S and is therefore also called the overlapping region O, whereas Edge region _R is defined as the region that lies outside overlap region O and is not irradiated with each pulse based on movement of laser beam axis BA along contour C. FIG.

Figures (1) to (4) in FIG. 7 are schematic diagrams showing examples of how holes (perforations) are drilled in the hole base _Hb . Irradiation with laser radiation LS causes the opening H (perforation) of the component 1 to step radially outward, as seen by the widening black surface, starting from the location of the hole axis _Ha . expanding. The edges of the circular surfaces shown in black represent the respective hole walls _HW of the holes H of the component 1 .

As a result, the diameter D _H of the hole H in the underside of the component 1 =2·H until the asymptotic shape of the hole H to be achieved is reached and further irradiation of the energy flux density causes no further ablation. r _{B, bot} spreads.

As shown in FIG. 7-(1), opening of the hole H has not been achieved or through perforation has not been achieved at the start of the irradiation with the laser beam LS. That means that in order to achieve the aperture, the applied laser beam unit continues to irradiate with laser radiation LS, meanwhile the direction R It is to move the spot plane S along _C multiple times.

The laser beam unit constantly irradiates the overlap area O with the laser radiation LS while moving the spot surface S. Therefore, the time-averaged energy flux density of the laser radiation LS in the overlap region O is higher than in the edge region R.

Therefore, as shown in FIG. 7-(2), the opening or hole H in the bottom of the hole is first opened in the overlap region O. Then, as shown in FIG. With further irradiation, the aperture widens (FIG. 7-(3)), and finally the aperture H assumes its full diameter (FIG. 7-(4)).

In addition, the time span in which the laser beam LS is emitted tends to become shorter radially outward from the hole axis _Ha via the edge of the overlap region O. As shown in FIG. Correspondingly, the formed opening extends radially outward from the overlap region O until the diameter of the opening reaches the predefined hole wall _Hw to produce the predefined hole H. (See also FIG. 6E for this).

FIG. 7 also demonstrates through the iconographic sequences (1)-(4) that single pulse/percussion drilling and trepanning drilling are performed simultaneously. At the same time, it is meant that the laser beam is guided in such a way that the central area O is completely illuminated with each pulse of laser radiation LS, the beam axis B _A relative to the beam axis B _A of the previous pulse. , so that only part of the edge region is illuminated during one pulse.

The beam diameter D _S of the laser beam LS should not be adjusted less than half the hole diameter D _H to be achieved (D _S >D _H /2) (see FIG. 5). Such a strategy ensures that the central region O is irradiated with a relatively high energy flux density and is irradiated with radiation for the entire drilling time for cw radiation or with each pulse for pulsed radiation. is guaranteed to be formed.

Also, the diameter D _C of the trajectory curve C should not be adjusted larger than the beam diameter D _S in order to ensure that the entire central region O is loaded with radiation without gaps in time during the entire drilling time. , thus D _S <D _C (see FIG. 5). Such measures also ensure that the central region O is formed.

In the method described with the aid of the figures described above, care must be taken that multiple reflections of the laser radiation do not change the hole shape. According to the present invention, the final asymptotic hole shape is uniquely defined by the spatial distribution of the energy flux density of the laser radiation and the movement of the beam axis, and multiple reflections and thus repeated irradiations are undesirable. . Such multiple reflections are such that for example the spot diameter D _S and the trajectory diameter D _C are sized such that an aspect ratio A=d/(2 r _B,top ) of less than 10 is observed. avoided by Multiple reflections occur when the hole diameter is small and the hole depth is large, which means that the aspect ratio is typically greater than ten.

In order to carry out the method according to the invention, the movement of the beam axis B _A of the radiation LS can be carried out with the scanner during drilling, the movement of the beam axis B _A being periodically passed at least once. , along a closed trajectory curve C with diameter D _C .

As already mentioned, the spot surface S, i.e. the cross-sectional area of the laser radiation LS perpendicular to the beam axis B _A , is smaller than the area of the aperture, i.e. the area in which the holes H are stepped. . The laser machining apparatus used can prevent concentration of the energy flux density of the laser radiation LS at the edge of the opening, by applying the method according to the invention, to the inner circumferential area I of the hole. (See FIG. 7), it is also consequential that the deterioration of the shape accuracy of the opening can be prevented by moving the spot surface S along.

The pictorial sequence (1)-(4) of FIG. 8 shows a trepanning process applied according to the prior art for producing holes. In the trepanning process, the spot area SX is moved along the inner circumferential area I of the hole contour to be generated, but there is no overlapping area superimposed on the spot area at any point in time of the irradiation. . A laser machining device for performing such a trepanning process according to the prior art first emits laser light, which is indicated by the spot area SX1 (see fig. A hole is made in the center. This means that such holes are created for the discharge of molten material and extend through the entire thickness of the component. Next, the irradiation position of the laser beam moves in the radial direction to the spot position SX2 (see figure (2)). Following this, the irradiation position of the laser light moves along the inner circumferential area I, thereby changing the spot area to position SX3 (see icon (3)). Such movement of the spot area is then repeated according to the icon (4).

FIG. 9 shows schematically a first embodiment according to the invention with which the method described above can be implemented.

In the context of the following description of various embodiments and configurations of the device, when discussing the radiation guide for the laser radiation LS, reference numerals will also be used as they relate to FIGS. The descriptions and parts corresponding to the reference numerals of , will not be described again with reference to FIGS. It should also be explicitly pointed out that in describing the various embodiments illustrated in the drawings, components and method steps associated with one embodiment may have been previously described or described with reference to another embodiment. If there is, it is not necessary to explain all of them again. Accordingly, descriptions of various components associated with one embodiment can be transferred to respective components of other embodiments without explicit reference to such.

The apparatus of FIG. 9 supplies laser radiation LS with beam axis B _A and beam diameter D _S via optical fiber 11 and output device 12 of first galvanometer scanner unit 13 and from there to second galvanometer scanner unit 14 . , which has at least one laser beam unit 10 which directs laser radiation LS via optics 15 onto the component 1 . Both the beam unit 10 and the first and second galvanometer scanner units 13 , 14 are controlled through a control unit 16 . This control is such that the spot plane defined as the area (see cross-section S in FIGS. 6A-6E) illuminated by the laser radiation LS onto the surface of the top surface 2 of the component 1 is aligned with the hole H to be made. A portion of the spot surface S overlaps inside the inner circumferential area of the hole _H. is performed to generate region O.

The laser radiation LS is pulsed. However, continuous wave lasers or cw radiation can also be used. Additionally, the laser light LS can be provided by any laser source, such as a YAG laser, a _CO2 laser, or a disk laser. Also for the beam shape of the laser radiation, i.e. for the distribution of the energy flux density or the distribution of the intensity distribution perpendicular to its beam axis BA, for example a Gaussian, top _- hat or super-Gaussian type is applicable. .

The glass fiber 11 amplifies the laser light LS by reflecting the laser radiation LS inside the fiber. The diameter of the laser radiation LS emerging from the glass fiber 11 depends on the diameter of the glass fiber 11 . The radial diameter required for processing the component 1 can thus be adjusted in a simple manner by exchanging the glass fibers. However, it is also possible to adjust the radial diameter of the laser radiation LS impinging on the upper surface 2 of the component 1, for example via a corresponding optical system or by using a fiber laser. If a fiber laser is used, the glass fiber 11 and control unit 16 are not required.

An apparatus such as that shown in FIG. 9 allows the fabrication of holes _H with a hole diameter DH smaller than 1 mm, applying the method described above with reference to FIGS. 5 and 6A-6E. FIG. 10 schematically shows another device with which the method according to the invention can be implemented. This device is comparable to that of FIG. It is distinguished from the device of FIG. 9 by the provision of an auxiliary gas supply unit 18 . Via such an auxiliary gas supply unit 18 , auxiliary gas is supplied to the component 1 such that after the through-drilling a mass flow of the auxiliary gas flows through the hole in the region of overlap. This auxiliary gas serves to remove the material melted by the laser radiation LS from the hole in the direction of the flowing auxiliary gas. As a result, the molten material drawn out cannot be solidified on the hole wall, so that the machining accuracy of the hole H can be improved. Oxygen, air, nitrogen gas, argon gas, or mixed gases, for example, can be used as auxiliary gases. It is also conceivable for a liquid, for example water, to be supplied to the bore H by means of a corresponding water jet instead of the auxiliary gas.

As can be seen in FIG. 10, the distance _DG between the nozzle outlet 19 and the top surface 2 of the component 1 is between the exit side of the optics 15, seen in the beam direction of the laser radiation LS, and the top surface 2 of the component 1. are adjusted to be larger than the interval D _L of , respectively, when viewed in the Z direction. Such an adjustment serves to adjust the minimum mass flow of the auxiliary gas through the hole and not to flow over the upper surface of the component already at the hole entrance. However, if the component 1 is to be drilled with oblique or oblique holes, for example as shown in FIGS. 1-3, the distance D _L is chosen to be wider than the distance D _G .

The auxiliary gas supply unit 18 supplies the auxiliary gas under a pressure of at least 400 kPa or more, ie in the range of 400 kPa to 1000 kPa, in order to achieve a discharge action on the liquid melt. supply. The method of the present invention, in which single pulse/percussion drilling and trepanning drilling are performed simultaneously, allows working with auxiliary gas pressures that are much lower than in conventional methods. This is because in the method according to the invention the melt is carried away from the hole H through the upper surface 2 of the component 1 in a direction opposite to the direction of the laser beam, substantially under pressure due to evaporation. During drilling, auxiliary gas can only be supplied temporarily, and only if through drilling is performed in the overlap region.

An auxiliary gas supply unit 18 laterally supplies the component 1 with an auxiliary gas via a nozzle outlet 19 so that the melt can be extruded or conveyed out of the hole H. FIG.

The galvanometer scanner units 13 and 14 move the position of the spot surface S by reflecting the laser light, and at the same time change the optical path of the laser radiation LS. This laser processing apparatus always provides an overlap region O partially overlapped by the cross-section or spot plane of the laser radiation LS, between which the spot region S along the inner circumferential area I of the hole H to be made. Since laser processing is performed so as to move the , holes can be processed by such a laser processing apparatus using a galvanometer scanner unit.

For example, when machining of one hole is completed, machining of the next hole can be started simply by adjusting the rotation angle of the mirror body of the galvanometer scanner unit, thereby directing laser radiation in the direction of the next hole. For example, material processing can be expedited through the use of a galvanometer scanner unit. It is also contemplated to utilize beam splitters to direct laser radiation and thus control multiple optical systems simultaneously. Instead of a scanner, an optical system is utilized for beamforming, so for uninterrupted cw machining and for pulsed machining, the central region O and edge of the hole H to be made. It is also contemplated to adjust the distribution of the radiation to the region R differently in each temporal average.

Yet another embodiment of the device is shown schematically in FIG. In contrast to the device of FIG. 10, no galvanometer scanner unit is provided.

In this embodiment, laser radiation LS is coupled into nozzle cutting head 20 via glass fiber 11 .

This nozzle cutting head 20 includes an optical system 21 , a lens cylinder 22 and an auxiliary gas nozzle 23 .

The nozzle cutting head 20 is positioned on the upper surface of the component 1 in order to move the laser radiation LS on a trajectory along the inner circumference of the hole H to be made (see FIGS. 5, 6A-6E in this regard). or along a direction parallel to the top surface 3, ie along any trajectory in the two-dimensional coordinate plane XY. Instead of moving the nozzle-cutting head 20, a mounting table (not shown) carrying the component 1 can also be moved, thereby achieving relative movement between the nozzle-cutting head 20 and the mounting table. However, it is preferable to keep the mass to be moved small.

Claims (17)

In a method for drilling a component (1) made of metallic material and a component (1) made of laminated metallic and dielectric materials by single pulse drilling or percussion drilling and by trepanning drilling, a beam Laser radiation (LS) with axis (B _A ) and beam diameter (D _S ) and main melt ejection are performed, single pulse/percussion drilling and trepanning drilling are performed simultaneously,
That is, the spatial distribution of the Poynting vector (<S>) assigned to the laser radiation, defined as the vector indicating the direction of radiation propagation and whose value is the energy flux density of the laser radiation (LS), is the hole axis ( H _a ), the hole wall (H _w ), and the hole bottom (H _b ) in the overlapping area (O) of the hole to be generated (H) to be assigned a hole base (H _b ) called b ) and in the edge area (R) of the hole to be generated (H), respectively separately wherein the overlap region (O) is defined as the region irradiated with a high energy flux density of laser radiation in the case of single pulse drilling and the edge region (R) is defined by the Defined as a region located outside the overlap region (O) and irradiated with a low energy flux density of laser radiation (LS) during drilling, which is lower than the energy flux density in said overlap region (O), the aspect The maximum value A _max of the ratio A has a value lower than or equal to 10 with A=d/(2 _rB,top ), where d is relative to the top surface of the material (2) Material thickness of the material to be drilled through in the case of a vertical hole (H) or hole length in the case of a hole axis (H ^a ) inclined relative to the upper surface of the material (2) and rB,top is the hole radius of the hole (H) at the hole entrance, defined as the radius measured in the direction perpendicular to the hole axis (H _a ). Laser radiation (LS) during drilling is carried out such that the beam axis (B _A ) moves along a closed trajectory curve (C) to be traversed at least once, the beam diameter (D _S ) being Method according to claim 1, characterized in that it is at least as large as the diameter (D _C ) of the curve (C). Claim characterized in that the distribution of the radiation (LS) in the overlap region and the edge region (O, R) of the hole (H) to be achieved is adjusted differently with the temporal average value respectively. 3. The method according to 1 or 2. The Poynting vector (<S>) in the edge region (R) of the hole (H) has a directional component that varies with hole depth pointing towards the hole wall (H _W ) of the hole (H) to be achieved. A method according to any one of claims 1 to 3, characterized in that it comprises Reaching the asymptotic geometry of the hole (H) is the drilling time after which the hole (H) does not progress further with respect to its diameter (D _H ) and directly reaches its final shape. 5. Method according to any one of claims 1 to 4, characterized in that the time is guaranteed by being determined. The final shape of the hole is defined by the adjustment of the laser radiation (LS) to the rim region (R), reaching the final shape of the hole (H) in W cm ⁻² for pulse times longer than 1 ns, or a threshold defined as a number having a magnitude of J·cm ⁻² (equivalent to 10 ⁻⁴ W·m ⁻² or J·m ⁻² ) for a pulse duration shorter than 10 picoseconds, wherein the threshold is , surrogate for all other hole-related parameters known to characterize the material to be drilled, typically 10 ⁴ to 10 ⁵ W·cm ⁻² or 1 to 10 J·cm ⁻² for metallic materials. 6. A method according to any one of claims 1 to 5, characterized in that . The energy flux density of the laser radiation in said overlap region (O) in the case of drilling with multiple pulses is such that the melt is laser radiation (LS) before the material is through-drilled in said overlap region (O). is discharged from the hole (H) in the direction opposite to the propagation direction of the hole (H), the hole base (H _b ) reaches the material thickness, and the hole base (H _b ) at the bottom surface (3) of said component (1). 7. A method according to any one of claims 1 to 6, characterized in that the through perforations defined as opening are not yet produced. Melt ejection is based solely on evaporation pressure without the use of gas nozzles and the energy flux density at the overlap area (O) is such that the bottom of the hole (H _b ) is one at the overlap area (O). 8. Any of claims 1 to 7, characterized in that at the end of the pulse the underside (3) of the component (1) is reached and adjusted such that the asymptotic shape of the hole wall (H _w ) is not yet achieved. or the method according to item 1. No less than a minimum value for energy flux density and no more than a maximum value for energy flux density, said minimum value being at the bottom surface (3) of said component (1) at the bottom of the hole (H _b ) Determined by no through-drilling defined as the opening of the hole (H), said maximum value is such that the drilling time to reach the through-drilling increases exponentially with energy flux density. 9. A method according to any one of claims 1 to 8, characterized in that it is determined by: The final shape of the hole is determined by measuring the energy flux density of the laser radiation (LS) in said edge region (R), and the final shape of the hole is determined by the position of the hole wall ( _Hw ) where the measurement equals the threshold value. 7. Method according to claim 6, characterized in that it is predetermined. by adjusting the advance of the beam axis (B _A ) along a trajectory curve (C) of period time defined as the sum of the pulse time and the pulse pause between two successive pulses, and the laser By adjusting the incremental angle (Alpha), defined as the angle by which the beam axis (BA) of the radiation (LS) rotates about the hole axis (H _a ) during the cycle time on the trajectory curve (C) 3. A method according to claim 2, characterized in that, in cross-section, circular holes, figure-eight holes, oblong holes, or three-hole holes or star-shaped holes (H) are produced. Laser radiation (LS) with beam axis (B _A ) and beam diameter (D _S ) in an apparatus for drilling components made of metallic material and components made of stacked metallic and dielectric materials towards said component (1), and said component (1) having a radiation diameter DS irradiated at the upper surface (2) by laser radiation ( _LS ). 1) a control unit (12) for controlling said radiation unit (20) such that the beam axis (B _A ) and beam diameter (D _S ) characterize the position and cross-sectional area of the spot plane (S) defined as the region of ), the beam axis (B _A ) moves along a closed trajectory curve (C) and a portion of said spot surface (S) is within said trajectory curve (C) with an overlap area (O) A device that generates 13. Device according to claim 12, characterized in that the area of the overlap region (O) is smaller than the cross-sectional area with the diameter (D _H ) of the hole (H). The laser processing apparatus has a beam diameter (D _S ) of the spot surface (S) larger than half the length of the diameter (D _H ) of the hole (H), and the diameter (D _H ) of the hole (H) 14. Device according to claim 12 or 13, characterized in that it emits laser radiation (LS) such that it is smaller than . Said control unit (16) determines that the laser radiation (LS) extends the area of the hole of said component (1) out of said overlapping area (O) when viewed radially with respect to the hole axis (H _a ). 15. Apparatus according to any one of claims 12 to 14, characterized in that the laser beam unit is controlled to expand in the direction. characterized in that an auxiliary fluid supply unit (18) is provided for supplying fluid to the upper surface (2) of the component (1) and into the hole (H) formed in the component (1). 16. The apparatus according to any one of claims 12-15. Said laser processing apparatus comprises a beam unit (10) for generating pulsed laser radiation (LS) and reflection of the laser radiation (LS) for moving the center of the beam axis (B _A ) or spot plane (S). , and a galvano-scanner unit (13, 14) which at the same time changes the optical path of the laser radiation (LS) emitted by the beam unit (10). 3. Apparatus according to paragraph.

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