Method for sucking off particles, in particular when cutting individual printed circuit boards out of a sheet of circuit boards, suction device, suction system and cutting machine

Abstract

The invention relates to a method for sucking off particles (40) when cutting workpieces (11) out of a board material, and in particular when cutting individual printed circuit boards (12) out of a sheet of circuit boards (14), and to a suction device (28), a suction system (20) and a cutting machine (10), wherein, for the cutting out of the workpiece (11) and for the sucking off of the particles (40) arising during the cutting out, a compressed air flow (46a, 46b, 46c) pulsating at a pulse frequency is directed onto the workpiece in such a manner that particles (40) adhering to the workpiece (11) are detached, and / or that the workpiece (11) is set into vibration owing to the pulsating compressed air flow (46a, 46b, 46c) impinging thereon.

Description

[0001] Title : Method for extracting particles , particularly when separating individual printed circuit boards from a printed circuit board panel , extraction device , extraction system and separating machine

[0002] Description

[0003] The invention relates to a method for extracting particles when separating workpieces from a plate material, and in particular when separating individual circuit boards from a circuit board panel. Furthermore, the invention relates to a

[0004] Extraction device, an extraction system with such an extraction device and a cutting machine for cutting out workpieces from sheet material with such an extraction system and / or such an extraction device.

[0005] When using industrial automation systems, the use of highly efficient and precise manufacturing technology is a basic requirement. A key process step in the manufacture of electronic components is the separation of printed circuit board panels into individual assemblies, i.e. into individual printed circuit boards, after components have been populated and soldered. Given the complexity of today's assemblies and circuit structures, soiling and contamination of assemblies and printed circuit boards caused by the resulting particles and dust are extremely critical. This not only reduces production yields in electronics manufacturing; undetected defects in assemblies can have far-reaching consequences for product safety. It is therefore particularly important that particles and dust are captured and separated as completely as possible when processing printed circuit board panels and printed circuit boards.

[0006] It is well known that particles that are created can be extracted directly from the milling head or cutting head during machining. However, very small particles can become stuck to the workpieces and are not captured and removed by the suction of the extraction. These deposits can, among other things, cause unwanted short circuits between the connections of the electronic components of the individual assemblies. From an environmental point of view, minimal release of pollutants into the room air is also important. The resulting particles can impair the health of the operator of a depaneling or cutting machine if they are inhaled. Damage to the respiratory tract and the absorption of toxins into the body can be the result.

[0007] Investigations have also shown that the resulting milling particles are highly abrasive and lead to severe wear on components in the cutting machine. If the dust particles are not adequately removed, they can settle not only on the workpieces but also in the entire cutting machine. This, in turn, leads to breakdowns and higher costs due to wear and maintenance of the cutting machine. Breakdowns and deviations in tolerance are the result. Batches of machined workpieces can be of poor quality and cannot be reused for final products.

[0008] From DE 101 52 401 Al a milling machine with a chip extraction housing on the milling cutter is known.

[0009] From DE102018211278A1, a suction device for a machining device, in particular a machining device, is known, which has a compressed air channel that is designed to form a compressed air jet in the direction of the area to be cleaned. The present invention is based on the object of

[0010] To increase process reliability when separating workpieces, and in particular when separating individual circuit boards from a circuit board panel.

[0011] The object is achieved in particular by a method for sucking away particles when separating workpieces from a plate material, and in particular when separating individual circuit boards from a circuit board panel, according to claim 1. In particular, it is therefore provided that when separating the workpiece and when sucking away the particles created during separation, a compressed air stream pulsating at a pulse frequency is directed onto the workpiece in such a way that particles adhering to the workpiece are detached and / or that the workpiece is set into vibration due to the impacting pulsating compressed air stream.

[0012] This has the advantage that, on the one hand, particles can be detached directly from the circuit board by the pulsating compressed air flow and, on the other hand, that the circuit board can be set into vibration by the pulsating compressed air flow, whereby adhering particles, in particular dust and / or chips, are detached from the workpiece. The vibration of the workpiece also reduces the settling of particles that have not yet been extracted on the workpiece. Thus, the extraction according to the method according to the invention ensures an at least largely and ideally completely particle- and dust-free

[0013] End product, thereby increasing process reliability.

[0014] Very small particles in particular are not captured by known prior art extraction systems because the suction power, i.e. the possible negative pressure or volume flow that can be generated, is not sufficient and cannot be increased indefinitely. In the case of particles with a particle size in the range 40 to 80 pm, in particular smaller than 40 pm, as arise when individual assemblies are separated from printed circuit board panels, adhesion to the workpiece predominates. The adhesion of these particles is caused in particular by electrostatic charging of the particles, whereby adhesion forces act between the particles and the circuit board and / or the components. These particles can only be removed from the electrical assemblies mechanically using conventional methods, for example using moving brushes. This bears the risk that the often small and sensitive components applied and soldered to the circuit boards will be damaged or torn off.The method according to the invention enables the removal of extremely small particles from the surface of the printed circuit boards during the suction process with particles larger than 80 pm in a process-reliable manner, and the deposition of particles due to the vibration of the printed circuit board is reduced. In addition, the particle load inside the cutting machine is reduced, in particular in the processing area and on the cutting tool, which leads to a longer service life, longer cleaning and maintenance intervals, and thus lowers the costs of the manufacturing process. It has been shown to be advantageous if the pulse frequency is in the range of 1 - 60 Hz, in particular 20 - 40 Hz, and further in particular 30 Hz. These frequencies allow particles to be removed from the tool and printed circuit board, and the printed circuit board can be optimally excited to vibrate by the compressed air flow, without the components on it being damaged or becoming detached by the vibrations.

[0015] It is conceivable that the pulse frequency is predefined or adjustable and that the pulse frequency can be adjusted depending on workpiece parameters. To simplify the process, the pulse frequency can be predefined and controlled within a certain range. For other applications, for example when different circuit boards are separated one after the other, the pulse frequency can be adjustable. Advantageously and to further increase process reliability, the pulse frequency can be adjusted depending on workpiece parameters. This can be done manually, for example, or with the help of a database in which workpiece parameters are stored.

[0016] It is also advantageous if the workpiece's oscillation frequency is measured during the extraction process and the pulse frequency is regulated depending on the oscillation frequency. This is a beneficial development of the previous aspect, because by regulating the pulse frequency of the compressed air flow, the workpiece's oscillation frequency can always remain within a range safe for particle detachment. This can further increase process reliability.

[0017] It is also conceivable that the vibration frequency of the workpiece is measured using an optical camera or a vibration sensor. A camera is often already present in a cutting machine to detect the printed circuit board panels to be separated. The generated images can also be used to determine the vibration frequency. If the vibration amplitude of the vibrating printed circuit board panel is too small and cannot be detected by the camera, it is advantageous to provide a vibration sensor for reliable measurement of the vibration variables.

[0018] It is also advantageous if the compressed air forming the compressed air stream is ionized. Electrostatic potentials are built up by the friction of the cutting tool, in particular the milling cutter or a saw, during the cutting process. The electrostatic potential causes the particles to adhere more strongly to the printed circuit board panel. To avoid this, the electrostatic potential of the particles must be reduced. With ionized molecules in the compressed air, electrostatic potentials, in particular of the particles, can be reduced or equalized and the particles are released more easily from the printed circuit board panel, the circuit boards and the components of the cutting head. It can also be provided if the compressed air stream is generated by at least one and preferably three compressed air nozzles within a suction opening running around a central axis and forms a vortex around the central axis. The formation of a vortex further increases the detachment effect of the particles.

[0019] It has also proven advantageous if the extracted air volume flow, including particles, is greater than the injected compressed air flow. This ensures that a negative pressure, which leads to the extraction of the particles, can be reliably applied.

[0020] The object mentioned at the outset is also achieved by a suction device for sucking away particles when separating workpieces from a sheet material, and in particular when separating individual circuit boards from a circuit board panel, and further in particular for carrying out the method according to the invention. The suction device provides a suction opening running around a central axis and at least one compressed air nozzle provided for generating a compressed air flow directed along a main air flow direction. The compressed air nozzle is arranged in particular within the suction opening such that the main air flow direction is directed towards the workpiece to be separated. Furthermore, a compressed air line is provided for supplying the compressed air nozzle with compressed air.A valve unit is provided within the compressed air line, which is configured to generate a compressed air flow pulsating at a pulse frequency such that particles adhering to the workpiece are detached and / or the workpiece is set into vibration due to the impact of the pulsating compressed air flow. This can further increase process reliability.

[0021] It can further be provided that the valve unit is designed as an electrically controlled switching valve and that a control unit is provided for controlling the switching valve to generate the pulse frequency. This has the advantage of enabling simple control of the switching valve and integration of the method according to the invention into a commercially available control system or into a machine control system.

[0022] It has also proven advantageous if the switching valve is controlled by the control unit such that the pulse frequency is in the range of 1-60 Hz, in particular 20-40 Hz, and more particularly 30 Hz. Advantageously, the pulse frequency of the compressed air flow is transferred to the workpiece, which then vibrates to detach adhering particles.

[0023] It is also conceivable for the control unit to be configured to control the switching valve depending on workpiece parameters and / or depending on a measured oscillation frequency. This is advantageous because it ensures even greater process reliability by maintaining tolerances in the oscillation frequency.

[0024] It can further be provided that an ionizer is provided for ionizing the compressed air forming the compressed air stream. This allows the ionized compressed air to be generated near the cutting machine in order to ensure the best possible ionization of the air molecules used to form the compressed air. It is therefore advantageous if the at least one compressed air nozzle is made of a non-conductive material, in particular of a non-conductive plastic. The non-conductive plastic advantageously maintains the ionized state of the air molecules and the ionization of the air molecules is not balanced out until the compressed air of the compressed air stream hits the workpiece or the particles to be removed.

[0025] Furthermore, it can be provided that a nozzle ring forming the extraction opening is provided, on which the at least one compressed air nozzle and preferably three compressed air nozzles are arranged at an angular distance of 120° from one another. With three compressed air nozzles, a favorable mass of compressed air can be directed onto the workpiece by the compressed air stream. By arranging the compressed air nozzles on one component, the mountability on a cutting machine is advantageously designed.

[0026] It is advantageous if the main air flow direction of the at least one compressed air nozzle is such that, during operation, the compressed air flow creates a vortex around the central axis.

[0027] It can further be provided that the nozzle ring has a round outer contour with a flat spot, wherein one or more compressed air connections are provided at the flat spot.

[0028] It is also advantageous if the nozzle ring has, on an upper side facing the suction opening, a circumferential shoulder with a shoulder edge surrounding the suction opening, and if the at least one compressed air nozzle is provided on the shoulder edge. This has the advantage that the arrangement of the compressed air nozzle on the shoulder edge causes few disturbances in the compressed air stream emerging from the compressed air nozzle, allowing the stream to develop optimally.

[0029] The nozzle ring can have an upper side facing the suction opening and a lower side facing away from the suction opening, wherein the upper side and lower side are parallel to each other.

[0030] It is also conceivable for the nozzle ring to have a sensor receptacle for a tool sensor, with a sensor nozzle directed toward the sensor receptacle. The sensor is configured, in particular, to detect wear or breakage of the cutting tool. Due to particle deposits, the function of the sensor may be limited, since the sensor may, in particular, be an optical sensor. The sensor nozzle is advantageously configured to blow the deposited particles off the sensor using compressed air.

[0031] The object mentioned above is also achieved by an extraction system with a vacuum source, with vacuum lines for connecting an extraction device to the vacuum source, and with adjustment devices for adjusting the vacuum lines to a movable position of the extraction device, wherein the extraction device is an extraction device according to the invention and / or is operated according to the method according to the invention. Advantageously, the extraction device and the method according to the invention are adapted to one another in such a way that the extraction functions optimally and all components interact with one another. This leads to an increase in process reliability.

[0032] The object mentioned at the outset is also achieved by a separating machine for separating workpieces from a plate material, in particular individual circuit boards from a circuit board panel, having a separating head, having a central control unit, and having an extraction system with an extraction device according to the invention. This extraction device is operated in particular according to a method according to the invention, wherein the control unit is further designed in particular to control the separating head and the valve unit of the extraction device in parallel. Further details and advantageous embodiments of the invention can be found in the following description, on the basis of which exemplary embodiments of the invention are described and explained in more detail.

[0033] It shows :

[0034] Figure 1 : a separating machine for separating

[0035] Printed circuit boards from a printed circuit board panel with an extraction system with an extraction device;

[0036] Figure 2 : a schematic sectional view of the

[0037] Suction device according to Figure 1;

[0038] Figure 3 : a nozzle ring of the suction device according to

[0039] Fig. 1 ;

[0040] Figure 4: a plan view of the nozzle ring according to Fig. 3;

[0041] Figure 5 : a side view of the nozzle ring according to Fig. 4 ; and

[0042] Figure 6: a view of the cutting machine according to Fig. 1 from diagonally above into the suction opening.

[0043] Figure 1 shows a separating machine 10 for separating a workpiece 11 from a plate material, specifically for separating printed circuit boards 12 from a plate-shaped printed circuit board panel 14. The separating machine 10 comprises a separating head 16, a central control unit 17 (shown in Figure 2), and an extraction system 20. Axial drives for moving the separating head 16, as well as other components of the separating machine 10, are not shown for the sake of clarity.

[0044] The separating head 16 has a drive 18 and a separating tool 19, such as a milling cutter, for separating the printed circuit board 12 from the printed circuit board panel 14.

[0045] The suction system 20 comprises a vacuum source 22 and vacuum lines 24 with a connection 26 to a suction device 28, which is arranged on the cutting head 16. Furthermore, an adjusting device 30 is shown for adapting the vacuum lines 24 to the position of the suction device 28 in order to be able to follow the variable position of the movable cutting head 16. Preferably, several adjusting devices (not shown) are provided to enable the adaptation of the vacuum lines 24 in all directions of movement of the cutting head 16.

[0046] The suction device 28, which is also shown in Figure 2, comprises an annular nozzle ring 32 and a brush ring 34 arranged on the nozzle ring 32. The nozzle ring 32 forms a suction opening 36 about a central axis 38. Figure 6 shows a view obliquely from above into the suction opening 36. The brush ring 34, or rather its bristles, lie - as can be seen in Figure 6 - on the printed circuit board panel 14 and / or on the printed circuit board 12 when the printed circuit board 12 is cut out.

[0047] Figure 2 shows the extraction device 28 with the nozzle ring 32 in a simplified schematic view as a sectional view around the separating head 16. The drive 18 of the separating head 16, which is designed, for example, as an electric motor or pneumatic motor, drives the separating tool 19. The separating tool 19 processes the printed circuit board panel 14 and in the process separates individual printed circuit boards 26. Particles 40, such as dust and / or chips, are created during the separation process. Figure 2 also shows that the particles 40 created during the processing of the printed circuit board panel 14 are sucked away by an extracted air volume, indicated by the arrows 42, through the extraction opening 36 due to the negative pressure generated by the negative pressure source 22.

[0048] The nozzle ring 32 has a total of three compressed air nozzles 44a, 44b, and 44c, as shown in Figure 3, although only two compressed air nozzles 44a and 44b are shown in Figure 2 due to the sectional view. The compressed air nozzles 44a, 44b, and 44c each form a compressed air stream 46a, 46b, and 46c along a respective main air stream direction 48a, 48b, and 46c toward the printed circuit board 12 and / or the printed circuit board panel 14.

[0049] Furthermore, Figure 2 schematically shows an electric switching valve 50 having two compressed air connections 52 and 54. The compressed air connection 52 is connected to a compressed air source 56 and an air ionizer 58. The compressed air connection 54 is connected to a compressed air line 60, which connects the switching valve 50 to the compressed air nozzles 44a, 44b, and 44c in the nozzle ring 32.

[0050] The switching valve 50 is designed as an electrical quick-acting valve and has an interface 62. The switching valve 50 is connected to the central control unit 17 of the cutting machine 10 via the interface 62. The control unit 17 controls the switching valve 50 so that the switching valve 50 influences the compressed air, which originates from the compressed air source 56 and is advantageously ionized, and ultimately forms the compressed air streams 46a, 46b and 46c, in such a way that the compressed air streams 46a, 46b and 46c emerging from the compressed air nozzles 44a, 44b and 44c pulsate. The control of the switching valve 50 by the control unit 17 is carried out in particular such that the pulse frequency is in the range of 1 - 60 Hz. The pulse frequency can advantageously be variably adjusted to the workpiece parameters of the printed circuit board panel 14.

[0051] The pulsating compressed air streams 46a, 46b and 46c advantageously cause the printed circuit board panel 14 to vibrate and particles 40 deposited thereon, such as chips and / or dust, are removed or shaken off so that the detached particles 40 can be vacuumed away.

[0052] A sensor 64 shown in Figure 2 for recording the

[0053] The oscillation frequency of the printed circuit board panel 14 is coupled to the printed circuit board panel 14 and connected to the control unit 17. Using the oscillation frequency of the printed circuit board panel 14 as a measured variable, the oscillation frequency of the printed circuit board 12 can be regulated by the control unit 17. Furthermore, the control unit 17 is also connected, in particular, to the drive 18 of the cutting head 16 and controls it in parallel with the switching valve 50 during the cutting process, as well as other machine functions of the cutting machine 10.

[0054] During the separation process, the brush ring 34 rests against the printed circuit board panel 14 and / or the printed circuit board 12 to be separated and seals the extraction opening 36 against the environment 66, so that the negative pressure extends as far as the printed circuit board panel 14. This enables the capture and extraction of the particles 40 particularly well. It is advantageous if the air volume flow extracted by the negative pressure source 22, which is indicated by the arrows 42 in Figure 2, is at least as large as the volume of the particles 40 generated and released together with the volume of the injected compressed air flows 46a, 46b and 46c.

[0055] Figures 3, 4 and 5 show an embodiment of the nozzle ring 32 from Figures 1 and 2. The nozzle ring 32 has an annular base body which forms the suction opening 36 around the central axis 38. An upper side 70 lies facing the suction opening 36 and, parallel to it and below it at a distance d, a lower side 72. Furthermore, the nozzle ring 32 has a flat spot 74 on the outer contour 76, on which the two compressed air connections 78 and 80 are located. Furthermore, the nozzle ring 32 has the three compressed air nozzles 44a, 44b and 44c, which are connected to the compressed air connection 78. The compressed air connection 78 is connected to the switching valve 50 during operation.

[0056] The nozzle ring 32 further has a circumferential shoulder 82 with a shoulder edge 84 on the upper side 70, surrounding the suction opening 36. The three compressed air nozzles 44a, 44b, and 44c are arranged on the shoulder edge 84 at an angular distance a of 120° from one another.

[0057] The compressed air nozzles 44a, 44b and 44c are designed in such a way that they

[0058] Compressed air streams 46a, 46b, and 46c are directed along a respective main air stream direction 48a, 48b, or 48c, each indicated by arrows. The compressed air streams 46a, 46b, and 46c are directed onto the printed circuit board panel 14 and / or printed circuit board 12 in such a way that a vortex forms around the central axis 38. The main air stream directions 48a, 48b, and 48c do not run parallel to the central axis 38, but rather at an angle. As can be seen from Figure 4, the main air flow directions 48a, 48b and 48c, in plan view, preferably enclose an angle ß in the range of 45° to 90° with a respective tangent 49a, 49b and 49c applied to the shoulder edge 84. The respective tangent 49a, 49b and 49c lies at the center point of the compressed air nozzle 44a, 44b and 44c belonging to the main air flow directions 48a, 48b or 48c on the shoulder edge 84.In the vertical direction, as shown in Figure 5, the main air flow directions 48a, 48b and 48c in side view of the respective compressed air nozzle 44a, 44b and 44c enclose an angle y in the range of 0° to 30° with the central axis 38. For the sake of clarity, only the compressed air nozzle 44b, the compressed air flow 46b and the main air flow direction 48b are shown in Figure 5. Due to the combination of the arrangement of the compressed air nozzle 44a, 44b and 44c at the angle a and the formation of the main air flow directions 48a, 48b and 48c in the direction of the two angles ß and y, a vortex is formed around the central axis 38 by the compressed air flows 46a, 46b and 46c during operation of the suction device 28.

[0059] Furthermore, the nozzle ring 32 has a positioning bore 86, which is provided to ensure that the correct mounting position can be easily achieved when arranging the nozzle ring 22 on a cutting head 16 during replacement and / or maintenance. The positioning bore 86 ensures that the compressed air nozzles 44a, 44b, and 44c point in the direction of the cutting tool 19 during operation.

[0060] Furthermore, bores 88 are provided for mounting the brush ring 34 on the nozzle ring 32. A thread may be provided in the bores 88 for this purpose.

[0061] In addition, a sensor nozzle (not shown) is provided which is connected to the compressed air connection 80, as well as a sensor receptacle (not shown) for a tool sensor (not shown). This tool sensor can be optical, for example. With the help of the optical tool sensor, which is connected to the control unit 17, damage, breakage or wear of the cutting tool 19 can be detected during operation of the cutting machine 10. The status of the cutting tool 19 can be signaled to an operator or further automated processes to ensure process reliability can be carried out by the control unit 17. The sensor nozzle is provided to blow off any deposited particles 40 from the tool sensor with the help of compressed air in order to ensure proper functioning of the sensor. The compressed air can also pulsate and be supplied from the switching valve 50 via the compressed air line 60.

[0062] The nozzle ring 32 is preferably made of a non-electrically conductive plastic and is preferably manufactured additively. The compressed air ionized by the ionizer 58 remains ionized when the nozzle ring 32 is made of a non-conductive plastic. This allows the compressed air to further improve the removal of particles 40 adhering to the printed circuit board panel 14 and / or printed circuit board 12 or other machine components due to electrostatics.

[0063] Figure 6 shows a view of the cutting machine 10 in the

[0064] Suction opening 36 of the suction device 28 is shown. The

[0065] The cutting tool 19 of the cutting head 16 lies on the central axis 38 of the suction opening 36, with the suction opening 36 being surrounded by the nozzle ring 32. The brush ring 34 is arranged on the nozzle ring 32. The brush ring 34 is designed to be height-adjustable.

[0066] The extraction of particles 40 in the separating machine 10 is carried out in particular as follows:

[0067] Air is compressed into compressed air by the compressed air source 56, ionized by the ionizer 58 and fed to the compressed air line 60.

[0068] The electric switching valve 50 is controlled by the control unit 17 in such a way that the outflowing compressed air pulsates with a pulse frequency of, in particular, 1-60Hz.

[0069] The compressed air nozzles 44a, 44b and 44c in the nozzle ring 32 each form a pulsating compressed air stream 46a, 46b and 46c from the pulsating compressed air.

[0070] The pulsating compressed air streams 46a, 46b and 46c are directed along a respective main air stream direction 48a, 48b and 48c onto the printed circuit board panel 14 and / or the printed circuit board 12. By appropriately selecting the respective main air stream direction 48a, 48b and 48c, a vortex is formed around the central axis 38 of the extraction opening 36. Due to the pulsation of the compressed air streams impinging on the printed circuit board panel 14 and / or the printed circuit board 12

[0071] Compressed air streams 46a, 46b, and 46c detach particles 40 from the printed circuit board panel 14 and / or the printed circuit board 12. The detachment of the particles 40 is advantageously assisted by the vortex formed.

[0072] The pulse frequency of the pulsating compressed air streams 46a, 46b, and 46c impinging on the printed circuit board panel 14 and / or the printed circuit board 12 can be transferred to the printed circuit board panel 14 and / or the printed circuit board 12 and cause the printed circuit board panel 14 and / or the printed circuit board 12 to vibrate. As a result, particles 40 adhering to the panel by electrostatic forces are detached, essentially shaken off. The ionized state of the compressed air further reduces the electrostatic forces and promotes the detachment of the very small adhering particles 40.

[0073] By means of an applied vacuum 42, the dissolved particles 40 as well as the volume of the injected compressed air streams 46a, 46b and 46c are sucked away.

Claims

Patent claims Method for extracting particles (40) during the removal of workpieces (11) from a sheet material, and in particular during the removal of individual printed circuit boards (12) from a printed circuit board panel (14), characterized in that during the removal of the workpiece (11) and during the extraction of the particles generated during the removal (40) A pulsating compressed air stream (46a, 46b, 46c) is directed at the workpiece such that particles (40) adhering to the workpiece (11) are detached and / or the workpiece (11) is set into vibration due to the impact of the pulsating compressed air stream (46a, 46b, 46c). A method according to claim 1, characterized in that the pulse frequency is in the range of 1–60 Hz, in particular 20–40 Hz, and further in particular 30 Hz. A method according to any of the preceding claims, wherein the pulse frequency is predetermined or adjustable and wherein the pulse frequency is adjustable depending on workpiece parameters. A method according to any of the preceding claims, characterized in that a vibration frequency of the workpiece is determined during the extraction process. (11) is measured and that the pulse frequency is controlled depending on the oscillation frequency. Method according to claim 4, characterized in that the oscillation frequency of the workpiece (11) is measured by means of an optical camera or a vibration sensor (64). Method according to any of the preceding claims, characterized in that the compressed air forming the compressed air stream (46a, 46b, 46c) is ionized. Method according to any of the preceding claims, characterized in that the compressed air stream (46a, 46b, 46c) is generated by at least one and preferably three nozzles (44a, 44b, 44c) within a suction opening (36) extending around a central axis (38) and forms a vortex around the central axis (38). Method according to one of the preceding claims, characterized in that the extracted air volume flow including particles (40) is greater than the injected compressed air volume flow (46a, 46b, 46c). Extraction device (28) for extracting particles. (40) when separating workpieces (11) from a sheet material, and in particular when separating individual printed circuit boards (12) from a printed circuit board panel (14), and further, in particular, for carrying out a method according to one of the The preceding claims, comprising a suction opening (36) extending about a central axis (38), with at least one compressed air nozzle (44a, 44b, 44c) provided for generating a compressed air flow (46a, 46b, 46c) directed along a main air flow direction (48a, 48b, 48c), characterized in that the compressed air nozzle (44a, 44b, 44c) is arranged within the suction opening (36) such that the main air flow direction (48a, 48b, 48c) is directed towards the workpiece (11) to be cut, that a compressed air line (60) is provided for supplying the compressed air nozzle (48a, 48b, 48c) with compressed air, and that a valve unit (50) is provided within the compressed air line (60) which is used to generate compressed air pulsating at a pulse frequency The tstroms (46a, 46b, 46c) are arranged such that particles (40) adhering to the workpiece (11) are detached and / or that the workpiece (11) is detached due to the impact of the pulsating compressed air tstrom (46a, 46b,46c) is set into vibration. Extraction device (28) according to claim 9, characterized in that the valve unit (50) is designed as an electrically controlled switching valve and that a control unit (17) is provided for controlling the, A switching valve (50) is provided for generating the pulse frequency. A suction device (28) according to one of claims 9 or 10, characterized in that the switching valve (50) is controlled by the control unit (17) such that the pulse frequency is in the range of 1–60 Hz, in particular 20–40 Hz, and further, in particular 30 Hz. Extraction device (28) according to one of claims 9 to 11, characterized in that the control unit (17) is configured to control the switching valve (50) in To control depending on workpiece parameters and / or to regulate depending on a measured vibration frequency. Extraction device (28) according to one of claims 9 to 12, characterized in that an ionizer (58) is provided for ionizing the compressed air forming the compressed air stream (46a, 46b, 46c). Extraction device (28) according to one of claims 9 to 13, characterized in that a nozzle ring (32) forming the extraction opening (36) is provided, on which at least one compressed air nozzle (44a, 44b, 44c) and preferably three compressed air nozzles (44a, 44b, 44c) are arranged at a distance of 120° from each other. Extraction device (28) according to one of claims 9 to 14, characterized in that the nozzle ring (32) is located on a top surface (70) facing the suction opening a circumferential shoulder (82) surrounding the extraction opening (36) with a shoulder edge (84), and in that at least one compressed air nozzle (44a, 44b, 44c) is provided at the shoulder edge (84). Extraction device (28) according to one of claims 9 to 15, characterized in that the nozzle ring (32) has a sensor receptacle for a tool sensor, wherein a sensor nozzle directed towards the sensor receptacle is provided. Extraction system (20) with a vacuum source (22), with vacuum lines (24) for connecting (26) an extraction device (28) to the vacuum source (22), with adjustment devices (30) for adjusting the vacuum lines (24) to a movable position of the extraction device (28), wherein the extraction device (28) is an extraction device (28) according to one of claims 9 to 16 and / or is operated according to the method of claims 1 to 9.Separating machine (10) for separating workpieces (11) from sheet material, in particular individual printed circuit boards (12) from a printed circuit board panel (14), with a separating head (16), with a central control unit (17), and with an extraction system (20) according to claim 17 and an extraction device (28) according to one of claims 9 to 16, operated according to a method according to one of claims 1 to 9, wherein the control unit (17) is configured to control the separating head (16) and the. To control the valve unit (50) of the extraction device (28) in parallel.

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