Device, set and method for laser drilling a flat workpiece

Abstract

The invention relates to a device (10) for laser drilling a flat workpiece (12), having features of claim 1, a set (36) for laser drilling a flat workpiece (12), having features of claim 6, and a method for laser drilling a flat workpiece (12), having features of claim 8.

Description

[0001] Device, set and method for laser drilling a flat workpiece

[0002] Description

[0003] The invention relates to a device for laser drilling a flat workpiece with features of claim 1, a set for laser drilling a flat workpiece with features of claim 6 and a method for laser drilling a flat workpiece with features of claim 8.

[0004] Laser drilling uses a laser beam to create a large number of through holes in a workpiece at a high cycle rate, each with a small spacing between them. Due in particular to the high cycle rate and the small spacing between the individual through holes, the workpiece can heat up, warp, and possibly crack or become damaged.

[0005] It is therefore the object of the present invention to provide a device, a set and a method for laser drilling a flat workpiece, wherein the above disadvantages are eliminated.

[0006] The above object is achieved by a device for laser drilling a flat workpiece with a top side and a bottom side having the features of claim 1.

[0007] The device comprises a laser device for generating and focusing a laser beam onto the workpiece in such a way that the laser beam creates at least one through-hole (which can also be referred to as a bore or drilled hole) in the workpiece. The device further comprises a differential pressure device for generating a differential pressure between a medium on the top side and a medium on the bottom side of the workpiece, such that a flow of the medium through the through-hole can be generated due to the differential pressure. The medium (which can also be referred to as the ambient medium) can be a gas, a liquid and / or a gas-liquid mixture. In particular, the medium can flow through the through-hole due to the differential pressure. The medium can be colder than the workpiece.

[0008] In this context, differential pressure refers to a pressure difference. Specifically, differential pressure is the difference in a pressure curve between a point on the top side and a point on the bottom side of the workpiece.

[0009] This allows for simple cooling of the workpiece during laser drilling. Damage to the workpiece can be avoided despite high cycle rates and small spacing between numerous through holes. Less distortion of the workpiece due to heat input allows for more precise hole geometry and placement.

[0010] In this case, the terms "top," "above," "bottom," and "below" can refer to the top or bottom of the workpiece. In other words, the upward or downward direction can be defined by the orientation of the workpiece or its top and bottom. Likewise, the terms "top," "above," "bottom," and "below" can refer to a direction of gravity. Each through-hole created creates an opening in the workpiece through which, for example, a gaseous medium can flow. The gaseous medium can flow through the workpiece (or the through-hole or through-holes) due to the differential pressure between the medium on the top and the medium on the bottom of the workpiece. The gaseous medium can have a lower temperature than the workpiece, so a temperature difference can arise.By flowing through the through holes of the workpiece, thermal energy can be dissipated by convection and heat conduction both from a surface and from the (entire) volume of the workpiece.

[0011] The gaseous medium can be air, in particular ambient air. The gaseous medium can be a gas or a gas mixture. The gaseous medium can, in particular, be a mixture of a gas and a liquid, such as humid air and / or fog. This allows for better heat dissipation due to the higher heat capacity of the humid gaseous medium.

[0012] The drilling depth, and thus the thickness of the workpiece, can be less than or equal to 3 mm (millimeters), in particular less than or equal to 500 pm (micrometers). The aspect ratio between depth and minimum width (or minimum diameter) of the hole can be in a range of less than or equal to 100:1, in particular less than or equal to 10:1. The through hole (i.e. the hole), in particular each of the through holes produced, can have a diameter in the micrometer range, in particular of at most 100 pm, preferably of at most 50 pm.

[0013] The laser device can comprise a pulsed laser. The laser device can comprise a fiber laser (single-mode laser) or a disk laser (multi-mode). The laser beam generated by the laser device can have a variable beam profile during laser drilling, with stepwise switching between a Gaussian or top-hat-like beam profile and a ring-like beam profile, and the associated intermediate stages.

[0014] The laser device can be configured to generate a laser beam with a beam parameter product in the range of 0.38-32 mm*mrad (millimeters times milliradians), in particular less than or equal to 0.6 mm*mrad (single-mode-like). The laser device can be configured to generate a laser beam with a beam parameter product in the range of less than or equal to 32 mm*mrad, in particular less than or equal to 4 mm*mrad (multi-mode).

[0015] The laser device can be configured to generate a laser beam whose beam diameter dw on the workpiece is in the range 10pm- 800pm (micrometers), in particular 20pm-50pm for single-mode and 50pm-200 pm for multi-mode.

[0016] The laser device can be configured to generate a laser beam with a fluence H of less than 500 kJ / mm A 2 (kilo joule / square millimetre), in particular less than or equal to 100 kJ / mm A 2 . The laser device can be designed to generate a laser beam with an intensity I of less than 15000 kW / mm A 2 (kilowatts / square millimetre), in particular less than or equal to 6500 kW / mm A 2 , to generate .

[0017] The laser device can comprise an infrared laser with a wavelength in the range of 800-1200 nm (nanometers), in particular 1030 nm or 1070 nm.

[0018] The laser device may comprise a laser having a wavelength in a visible range, in particular in a range of 400-450 nm (blue) and / or 515 nm (green).

[0019] The laser device may comprise a CO2 laser with a wavelength of approximately 10 gm.

[0020] The laser device can be configured to generate a laser beam with an average laser power P ( av) in a range of 2-5000 W (watts), in particular in a range of 20-2000 W.

[0021] The laser device can be configured to generate a laser beam with a pulse peak power P (peak) in a range of 20-20000 W, in particular in a range of 500-7000 W.

[0022] The laser device can be configured to generate a laser beam with a pulse frequency f in a range of 25–50,000 Hz (Hertz), in particular in a range of 250–5,000 Hz. The laser device can be configured to generate a laser beam with an interchangeable beam profile and beam diameter during a pulse. This allows a continuous change of the drilling diameter in the drilling direction to be achieved.

[0023] The laser device can be configured to generate a laser beam with a pulse shape that can be rectangular, triangular, and / or sinusoidal. This can improve coupling and achieve targeted evaporation and expulsion of the melt.

[0024] The laser device can be configured to generate a laser beam with a pulse duration t(pulse) of less than or equal to 1000 ms (milliseconds), in particular less than or equal to 1000 μs (microseconds), further in particular less than or equal to 100 μs. The laser device can be configured to generate a laser beam with a pulse duration t(pulse) of less than or equal to 500 ns (nanoseconds).

[0025] High pulse energies (greater than 50 mJ (millijoules)) allow for sufficient evaporation and melt expulsion. Short interaction times can lead to on-demand melting / heating and removal, as well as low heat input at the edges of the workpiece.

[0026] The laser device can comprise a scanner optics with an imaging ratio of 1:1 to 5:1, in particular 1.5:1 to 2:1. The laser device can comprise a flying optics with an imaging ratio of 1:1 to 5:1, in particular 1.5:1 to 2:1.

[0027] According to a further development of the device, the device can comprise a positioning device for positioning the workpiece. The positioning device can be trough-shaped, in particular in the form of a box. The workpiece can in particular be placed on the positioning device. The positioning device can comprise a hold-down plate which is designed to exert pressure (e.g. due to gravity) in particular from above onto the upper side of the workpiece and thus to fix the workpiece or to hold it in its position.

[0028] This allows the workpiece to be positioned using simple means.

[0029] According to a further development of the device, the device can comprise a clamping device for clamping the workpiece. The clamping device can, in particular, be configured to clamp the workpiece at its edges (in the longitudinal and / or transverse direction). The clamping device can, in particular, prevent the workpiece from sagging or slipping, in particular into the positioning device (downward).

[0030] This allows the workpiece to be clamped and thus handled precisely using simple means.

[0031] According to a further development of the device, the device can comprise a cooling device for cooling the workpiece, the positioning device, and / or the clamping device. In this case, cooling refers to active cooling (e.g., by adding a cooling gas and / or a cooling liquid or applying a lower temperature).

[0032] This allows the cooling effect to be further optimized using simple means.

[0033] According to a further development of the device, the differential pressure device can comprise a suction device and / or a blower device. The suction device and / or the blower device can be arranged below the workpiece, the through-hole, the positioning device, and / or the clamping device. The suction device and / or the blower device can be arranged at least partially within the positioning device.

[0034] This allows the differential pressure to be generated using simple means.

[0035] The suction device can comprise a suction opening for sucking out the medium (e.g. air). Alternatively or additionally, the blower device can comprise a blower opening for blowing the medium (e.g. air). The suction opening and / or the blower opening can each have a cross-section that is many times larger than the cross-section of the (individual) through-hole. There can be a large number of through-holes in the workpiece. During drilling, the workpiece can be positioned over the suction opening in such a way that the entire suction opening is covered by the workpiece. The opening cross-section of the suction opening can in this way define a processing area within which several drill holes (or

[0036] Through holes), e.g. at least 10 or at least 100 drill holes, can be produced.

[0037] In the case of an extraction system located below the workpiece, particularly below the through-hole, vapors, emissions, and / or smoke that may arise during laser drilling of the workpiece are extracted downward through the through-hole (i.e., away from the laser beam and the top of the workpiece). This prevents interference contours that may be formed by the vapors, emissions, and / or smoke.

[0038] In addition, vapors, emissions, and / or smoke that could be harmful or toxic to a user, for example, can be specifically extracted and removed. The flow can capture the vapors, emissions, and / or smoke generated during laser drilling directly at the source and in the vicinity of the workpiece. The captured vapors, emissions, and / or smoke can be removed by the flow.

[0039] The suction device can create a negative pressure, particularly in the positioning device, on the underside of the workpiece. Ambient pressure (or positive pressure) on the top side of the workpiece can generate the differential pressure that drives the flow through the through-hole in the direction of the negative pressure (i.e., downward).

[0040] Alternatively, the negative pressure can be created on the top side of the workpiece, with ambient pressure (or positive pressure) present on the bottom side. This can create a flow through the through-hole (in the opposite direction, i.e., upwards).

[0041] The suction device can, in particular, generate a negative pressure in the positioning device (e.g., designed as a box or tray). The positioning device can act as a compensating tank, so that a uniform differential pressure and thus the same cooling effect can be generated across the entire underside of the workpiece, which is to be drilled or perforated with through holes.

[0042] The above object is achieved by a set for laser drilling a flat workpiece having a top side and a bottom side with the features of claim 6. The set comprises at least one device according to the above embodiments and at least one flat workpiece.

[0043] Regarding the advantages achievable with the set, reference is made to the relevant information on the device. Further configuration of the set may be achieved by the measures described in connection with the device and / or those explained below.

[0044] According to a development of the set, the workpiece can be formed from one layer or from several layers. Each layer can comprise metal, ceramic and / or polymer. Each layer can be formed from metal, ceramic and / or polymer. It is conceivable that at least two, in particular all, layers can be formed identically (in particular from the same material). It is also conceivable that at least two, in particular all, layers can be formed differently (in particular from different materials).

[0045] This allows a wide range of materials to be used and makes laser drilling more flexible.

[0046] The above object is achieved by a method for laser drilling a flat workpiece having a top side and a bottom side with the features of claim 8. The method comprises the steps:

[0047] Preparing the workpiece.

[0048] Laser drilling of at least one through hole in the workpiece.

[0049] Creating a differential pressure between a medium on the top and bottom of the workpiece, so that the differential pressure causes the medium to flow through the through-hole. The medium may be colder than the workpiece.

[0050] This allows for simple cooling of the workpiece during laser drilling. Damage to the workpiece can be avoided despite high cycle rates and small spacing between numerous through holes. Less distortion of the workpiece due to heat input, allowing for more precise hole geometry and arrangement.

[0051] According to a further development of the method, the differential pressure between the medium on the top side and the medium on the bottom side of the workpiece can be generated by applying a negative pressure (e.g. suction) to the medium on the bottom side and / or an overpressure (e.g. blowing) to the medium on the top side of the workpiece.

[0052] In this way, the differential pressure can be generated using simple means.

[0053] According to a further development of the method, the differential pressure between the medium on the upper side and the medium on the underside of the workpiece can be generated by applying an overpressure (e.g. blowing) to the medium on the underside and / or a negative pressure (e.g. suction) to the medium on the upper side of the workpiece.

[0054] In this way, the differential pressure can be generated using simple means.

[0055] According to a further development of the method, the method may comprise the step:

[0056] Positioning, clamping and / or fixing the workpiece. This can be implemented in particular by means of a positioning device and / or a clamping device. It is also conceivable that the workpiece can be fixed by applying a negative pressure (e.g. suction) to the underside and / or by applying positive pressure (e.g. blowing) to the top of the workpiece, in particular at the positioning device. It is also conceivable that the workpiece can be fixed by placing a hold-down plate on it. This allows the workpiece to be positioned, clamped and / or fixed using simple means. The process can thus be further optimized.

[0057] According to a further development of the method, the method may comprise the step:

[0058] In addition to the medium, a gas, a liquid and / or a gas-liquid mixture is supplied so that the gas, the liquid and / or the gas-liquid mixture flows through the through-hole due to the differential pressure between the medium on the top and the medium on the bottom of the workpiece. A gas, a liquid and / or a gas-liquid mixture with a high heat capacity can be used here. It is also conceivable that the gas, the liquid and / or the gas-liquid mixture has a lower temperature than the workpiece and / or the ambient temperature.

[0059] This allows the cooling effect to be increased and the process to be further optimized.

[0060] According to a further development of the method, the method may comprise the step:

[0061] (Active) cooling of the workpiece, the positioning device, and / or the clamping device. This can be achieved, in particular, by means of a cooling device.

[0062] This allows the cooling effect to be further increased and the process to be further optimized. According to a further development of the process, a device as described above and / or a set as described above can be used to carry out the process.

[0063] With regard to the advantages achievable with the method, reference is made to the relevant explanations of the device and / or the set. The measures described in connection with the device and / or the set and / or those explained below may serve to further refine the method.

[0064] Further features, details and advantages of the invention will become apparent from the wording of the claims and from the following description of exemplary embodiments with reference to the drawing. It shows:

[0065] Fig. 1 is a schematic representation of a device for laser drilling a flat workpiece with a top side and a bottom side.

[0066] In the following description and in the figures, corresponding components and elements bear the same reference symbols. For the sake of clarity, not all reference symbols are shown in all figures.

[0067] Figure 1 shows a schematic representation of a device 10 for laser drilling a flat workpiece 12 with a top side 14 and a bottom side 16.

[0068] The device 10 comprises a laser device 18 for generating and focusing a laser beam 20 onto the workpiece 12 such that the laser beam 20 generates at least one through-hole 22 in the workpiece 12. It can be a

[0069] A plurality of through-holes 22 are produced in the workpiece 12 by means of the laser beam 20. For the sake of clarity, only one through-hole 22 is shown in the workpiece 12.

[0070] The device 10 comprises a differential pressure device 24 for generating a differential pressure between a medium on the upper side 14 and a medium on the lower side 16 of the workpiece 12, so that a flow of the medium through the through-hole 22 can be generated due to the differential pressure.

[0071] The device 10 can comprise a positioning device 26 for positioning the workpiece 12. The positioning device 26 can be trough-shaped, in particular in the form of a box (optionally open in the direction of the workpiece 12). In Figure 1, the workpiece 12 is shown placed on the positioning device 26.

[0072] The device 10 may comprise a clamping device 28 for clamping the workpiece 12. The clamping device 28 is arranged above the positioning device 26 in Figure 1. In this case, the workpiece 12 is clamped or held between the clamping device 28 and the positioning device 26.

[0073] The device 10 can comprise a cooling device 30 for cooling the workpiece 12, the positioning device 26, and / or the clamping device 28. The cooling device 30 can be designed as an air conditioning system or as a heat exchanger. The cooling device 30 in Figure 1 is at least partially configured to cool the workpiece 12, the positioning device 26, and the clamping device 28.

[0074] The differential pressure device 24 may comprise a suction device 32 and / or a blower device 34. The suction device 32 and / or the blower device 34 may each be arranged below the workpiece 12, the through-hole 22, the positioning device 26, and / or the clamping device 28. The differential pressure device 24 in Figure 1 comprises the suction device 32 and the blower device 34.

[0075] The suction device 32 can be configured to generate a vacuum by sucking out gas (e.g. air), liquid (e.g. moist air, mist) and / or gas-liquid mixture on the underside 16 of the workpiece 12 (indicated in Figure 1 by means of a long arrow).

[0076] The blower device 34 can be configured to generate an overpressure by blowing gas (e.g. air), liquid (e.g. moist air, mist) and / or gas-liquid mixture onto the underside 16 of the workpiece 12 (indicated in Figure 1 by means of a long arrow).

[0077] The device 10 according to the above embodiments, in particular the device shown in Figure 1, and at least one flat workpiece 12 with an upper side 14 and a lower side 16 can represent a set 36.

[0078] The workpiece 12 can be formed from one layer or from multiple layers. Each layer can comprise metal, ceramic and / or polymer. Each layer of the workpiece 12 can be formed from metal, ceramic and / or polymer. It is conceivable that at least two, in particular all, layers of the workpiece 12 can be formed from the same material. It is also conceivable that at least two, in particular all, layers of the workpiece 12 can be formed from different materials.

[0079] In the following, a method for laser drilling a flat workpiece 12 with a top side 14 and a bottom side 16 is described with reference to Figure 1. The method comprises the following steps:

[0080] Providing the workpiece 12 .

[0081] Laser drilling at least one through hole 22 in the workpiece 12 .

[0082] Generating a differential pressure between a medium on the top side 14 and a medium on the bottom side 16 of the workpiece 12, so that a flow of the medium through the through hole 22 is generated due to the differential pressure.

[0083] The differential pressure between the medium on the upper side 14 and the medium on the lower side 16 of the workpiece 12 can be achieved by applying a negative pressure (e.g. suction) to the medium on the lower side 16 and / or applying an overpressure (e.g. blowing) to the medium on the upper side 14 of the

[0084] workpiece 12 can be produced.

[0085] The differential pressure between the medium on the upper side 14 and the medium on the lower side 16 of the workpiece 12 can also be generated by applying an overpressure (e.g. blowing) to the medium on the lower side 16 and / or by applying a negative pressure (e.g. suction) to the medium on the upper side 14 of the workpiece 12.

[0086] The method may comprise the step of:

[0087] Positioning, clamping, and / or securing the workpiece 12. This can be implemented, in particular, by means of a positioning device 26, a clamping device 28, and / or a hold-down plate (not shown). It is also conceivable that securing the workpiece 12 can be implemented by applying a negative pressure to the underside 16 and / or an overpressure to the top side 14 of the workpiece 12.

[0088] The method may comprise the step of:

[0089] Supplying a (cooled) gas, a (cooled) liquid and / or a (cooled) gas-liquid mixture, so that the gas, the liquid and / or the gas-liquid mixture flows through the through-hole 22 due to the differential pressure between the medium on the upper side 14 and the medium on the underside 16 of the workpiece 12.

[0090] The method may comprise the step of:

[0091] (Active) cooling of the workpiece 12, the positioning device 26, the clamping device 28, and / or the hold-down plate. This can be implemented in particular by means of a cooling device 30.

[0092] To carry out the method, a device 10 according to the above embodiments, in particular the device shown in Figure 1, or a set 36 according to the above embodiments, in particular the set 36 shown in Figure 1, can be used.

Claims

Patent claims 1. Device (10) for laser drilling a flat workpiece (12) with a top side (14) and a bottom side (16), comprising: a laser device (18) for generating and focusing a laser beam (20) onto the workpiece (12) such that the laser beam (20) generates at least one through-hole (22) in the workpiece (12), a differential pressure device (24) for generating a differential pressure between a medium on the top side (14) and a medium on the bottom side (16) of the workpiece (12), such that a flow of the medium through the through-hole (22) can be generated due to the differential pressure.

2. Device (10) according to claim 1, characterized in that the device (10) comprises a positioning device (26) for positioning the workpiece (12).

3. Device (10) according to claim 1 or 2, characterized in that the device (10) comprises a clamping device (28) for clamping the workpiece (12).

4. Device (10) according to claim 2 or 3, characterized in that the device (10) comprises a cooling device (30) for cooling the workpiece (12), the positioning device (26) and / or the clamping device (28).

5. Device (10) according to one of the preceding claims, characterized in that the differential pressure device (24) comprises a suction device (32) and / or a blower device (34), wherein the suction device (32) and / or the blower device (34) are arranged below the workpiece (12), below the through-hole (22), below the positioning device (26) and / or below the clamping device (28).

6. Set (36) for laser drilling a flat workpiece (12) with a top side (14) and a bottom side (16), comprising at least one device (10) according to one of the preceding claims and at least one flat workpiece (12).

7. Set (36) according to the preceding claim, characterized in that the workpiece (12) is formed from one layer or from several layers, wherein each layer comprises metal, ceramic and / or polymer or is formed from metal, ceramic or polymer.

8. Method for laser drilling a flat workpiece (12) with a top side (14) and a bottom side (16) comprising the steps: Providing the workpiece (12); Laser drilling at least one through hole (22) in the workpiece (12); Generating a differential pressure between a Medium on the top (14) and a medium on the Bottom (16) of the workpiece (12) so that due to the differential pressure a flow of the medium is generated through the through hole (22).

9. The method according to claim 8, characterized in that the differential pressure between the medium on the upper side (14) and the medium on the underside (16) of the workpiece (12) is generated by applying a negative pressure to the medium on the underside (16) and / or an overpressure to the medium on the upper side (14) of the workpiece (12).

10. Method according to claim 8 or 9, characterized in that the differential pressure between the medium on the upper side (14) and the medium on the underside (16) of the workpiece (12) is generated by applying an overpressure to the medium on the underside (16) and / or a negative pressure to the medium on the upper side (14) of the workpiece (12).

11. Method according to one of claims 8 to 10, characterized in that the method comprises the step: Positioning, clamping and / or fixing the workpiece (12), in particular by means of a positioning device (26) and / or a clamping device (28).

12. Method according to one of claims 8 to 11, characterized in that the method comprises the step: Supplying a gas, a liquid and / or a gas-liquid mixture, so that the gas, the liquid and / or the gas-liquid mixture is forced due to the differential pressure between the medium on the upper side (14) and the medium on the lower side (16) of the Workpiece (12) flow through the through hole (22).

13. Method according to one of claims 8 to 12, characterized in that the method comprises the step: - cooling the workpiece (12), the Positioning device (26) and / or the clamping device (28), in particular by means of a cooling device (30).

14. Method according to one of claims 8 to 13, characterized in that a device (10) according to one of claims 1 to 5 or a set (36) according to claim 6 or 7 is used to carry out the method.

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