METHOD FOR LASER-BASED MACHINING OF A WORKPIECE AND LASER MACHINING DEVICE FOR PERFORMING THE METHOD

Description

[0001] The invention is based on a method for laser-based machining of an elongated workpiece which extends along a geometric workpiece longitudinal axis, see e.g. JP 2013 091095 A.

[0002] It is well known that workpieces can be processed using short, intense laser pulses. Laser radiation with a high power density heats the material on the workpiece's surface. The surface of the workpiece reaches such a high local temperature that the material vaporizes or sublimates. At a high laser power density, a plasma of electrons and ions from the removed material is created. Material removal is also referred to as laser ablation or laser vaporization. The material can be removed in layers, for example, across a large area. Furthermore, it is possible to cut through a workpiece using continuous or pulsed laser radiation. This is referred to as laser cutting or laser beam cutting. The parameters of the laser radiation must be adapted to the material being processed and the desired processing. These parameters include the wavelength and the average power.If the laser radiation is pulsed, the parameters also include the pulse energy and pulse duration.

[0003] For laser processing, the laser beam and workpiece are aligned relative to each other in a defined manner and, if necessary, moved to selectively remove material within specified areas of the workpiece and to create specific workpiece contours on the surface. This includes, among other things, creating cutting edges or other edges on workpieces.

[0004] A laser processing device is equipped with a laser that generates a laser beam. The laser beam extends along a beam axis. The beam axis corresponds to a geometric straight line. The laser comprises a laser head, which directs the laser beam with its beam axis precisely onto a workpiece and, if necessary, moves it across the surface of a workpiece within a predetermined workpiece contour. The workpiece is arranged in a device for alignment and positioning, which in a machine tool is also referred to as a clamping device. This device is equipped with a device base, a workpiece fixing device, and a movement device. The device base is stationary. It can be part of the machine base of the laser processing device.The workpiece fixation device holds the workpiece and clamps it securely so that the position of the workpiece relative to the workpiece fixation device remains unchanged during processing. The movement device ensures movement of the workpiece fixation device relative to the fixture base. Since the laser head of the laser processing device is generally stationary relative to the fixture base, the movement device also ensures relative movement between the laser head on the one hand and the workpiece fixation device on the other. Accordingly, a workpiece clamped to the workpiece fixation device is moved relative to a laser beam generated by the laser head.Thanks to the relative movement triggered by the movement device, a workpiece can be machined across its entire surface, provided the workpiece surface is not covered by the workpiece fixing device. During processing, the workpiece's surface is aligned with the laser beam at various angles. The laser head can be equipped with a laser deflection device that uses optical components to specifically deflect the laser beam and guide it at high speed over a surface of the workpiece. This deflection device ensures additional relative movement between the laser beam and workpiece. The speed at which the laser deflection device moves the laser beam is usually greater than the speed at which the movement device moves the workpiece relative to the fixture base.

[0005] To machine a workpiece, the laser beam is usually aligned with its beam axis towards the workpiece to be machined so that the beam axis is perpendicular to a surface of the workpiece. Material is then removed layer by layer from the surface of the workpiece until the workpiece has the desired workpiece shape. This type of process is only suitable for machining small areas of a workpiece, as layer-by-layer material removal is very time-consuming. For machining a workpiece along its entire lateral surface, in particular for creating an outer workpiece contour that extends over the circumference, this type of process with layer-by-layer material removal is unsuitable for reasons of time and cost. This applies, for example, if a drill or reamer is to be produced from a cylindrical blank.

[0006] The invention is based on the object of providing a method and a device for laser-based machining of a workpiece, with which a workpiece with a predetermined outer workpiece shape, which extends over the entire circumference at least in one axial section, can be produced from a blank with high precision, wherein the workpiece remains clamped in a workpiece fixing device during the entire machining process and reclamping of the workpiece is eliminated.

[0007] This object is achieved by a method having the features of claim 1 and by a laser processing device having the features of claim 17. The elongated workpiece to be machined extends along a geometric workpiece longitudinal axis. A predetermined three-dimensional outer workpiece shape with a workpiece contour is generated on the workpiece by material removal using the laser beam. The workpiece contour corresponds to the intersection of the three-dimensional outer workpiece shape to be generated with a geometric workpiece plane in which the geometric workpiece longitudinal axis runs. The workpiece contour extends between a first point A and a second point B,wherein points A and B are offset from one another at least in the axial direction. The method according to claim 1 is characterized in that the workpiece is arranged in a workpiece fixing device of a laser processing device and that three superimposed movements are carried out simultaneously, which lead to targeted material removal from the workpiece: A first movement is a workpiece rotation movement, in which the workpiece fixing device rotates the workpiece about the geometric longitudinal axis of the workpiece. This rotation is endless. The workpiece performs a continuous sequence of complete revolutions. Since the workpiece is rotated about the geometric longitudinal axis of the workpiece, the rotation takes place about a workpiece-specific axis of rotation.

[0008] A second movement involves targeted guidance of the laser beam. The laser beam is moved along a predefined laser path using the laser deflection device. This laser path corresponds to the workpiece contour of the predefined three-dimensional workpiece shape between point A and point B. During guidance of the laser beam, the laser beam is aligned perpendicular to the geometric workpiece plane or forms an angle of no more than 10° with a normal to the workpiece plane. A normal is a straight line perpendicular to the workpiece plane. During the second movement, the laser beam is guided several times along the laser path between A and B.

[0009] A third movement is a feed movement, in which the workpiece fixation device and / or the laser beam are advanced such that the surface of the workpiece arranged in the workpiece fixation device comes into contact with the laser beam in such a way that the laser beam is aligned tangentially to the surface of the workpiece or forms an angle of no more than 10° with the tangent to the surface of the workpiece. In this process, the laser beam removes material from the surface of the workpiece and creates the specified three-dimensional outer workpiece shape with the workpiece contour.

[0010] The three movements are superimposed in time. The first movement, the second movement, and the third movement are executed simultaneously and parallel to each other until the specified workpiece contour is created on the workpiece.

[0011] Since the workpiece is continuously rotated while the laser beam removes material from the outside of the workpiece, the material removal occurs similarly to a lathe on the entire outer circumference of the workpiece, at least in the axial section of the workpiece that extends between the two points A and B.

[0012] The material is not removed layer by layer, but rather entire sections along the circumference of the workpiece are removed. The first movement is a sequence of complete rotations of the workpiece around the workpiece's geometric longitudinal axis. The second movement can be repeated as often as required. For this purpose, the laser beam is moved back and forth several times along the laser path between the first point A and the second point B. The third movement ensures that the rotating workpiece and the laser beam guided along the laser path come into contact in such a way that material is removed from the outside of the workpiece in a targeted manner by the laser beam.

[0013] The workpiece contour is defined by the outer shape of the workpiece to be created. It corresponds to a curve that separates the workpiece, with the workpiece shape to be created, from its surroundings in the area to be machined using the process.

[0014] The specified three-dimensional outer workpiece shape can have different cross-sections in the axial section between the two points A and B. This results in the workpiece contour having different distances to the geometric longitudinal axis of the workpiece between points A and B.

[0015] The two points A and B are offset axially relative to the geometric longitudinal axis of the workpiece. They can also be offset radially from each other.

[0016] During the second movement, the laser beam is aligned to the workpiece in such a way that its beam axis is aligned perpendicular to the geometric workpiece plane in which the geometric workpiece longitudinal axis runs or forms an angle of no more than 10° with the geometric workpiece plane.

[0017] The laser path corresponds to the intersection between the geometric workpiece plane and the three-dimensional outer workpiece shape to be created. The intersection extends in the workpiece plane on both sides of the geometric workpiece longitudinal axis. For rotationally symmetric workpiece shapes, the intersection is axially symmetric to the geometric workpiece longitudinal axis. The laser path can run on only one side of the workpiece longitudinal axis or on both sides of the workpiece longitudinal axis.

[0018] The first, second, and third movements are coordinated in such a way that any desired external workpiece shape can be created. This includes rotationally symmetrical workpiece shapes and non-rotationally symmetrical workpiece shapes, for example, external workpiece shapes with flat surfaces.

[0019] The method according to the invention can produce an outer workpiece shape that extends over the entire outer circumference of the workpiece and has an axial extension relative to the workpiece's longitudinal axis. During this machining process, the workpiece remains clamped in the workpiece fixturing device. Machining is fast and precise.

[0020] A key advantage of the method according to the invention is that, with a focused laser beam, the focus is always at the position to be machined or very close to it during laser processing. This enables optimal machining of the workpiece.

[0021] According to a further advantageous embodiment of the invention, the laser beam is guided along the laser path from A to B and then from B to A. This movement can be repeated as often as desired until the specified workpiece shape is created on the workpiece.

[0022] According to a further advantageous embodiment of the invention, the laser beam is moved several times along the laser path from A to B, wherein the movement of the active laser beam occurs exclusively in the direction from A to B and not vice versa. In order to return the laser beam to point A after reaching point B, the laser beam is either switched off during the return movement or the return movement occurs with the laser beam activated along a curve which deviates from the laser path A - B predetermined by the workpiece contour to be created, wherein this curve extends outside the workpiece to be machined in order to avoid undesired interaction between the laser beam and the workpiece.

[0023] According to a further advantageous embodiment of the invention, the laser beam is moved substantially perpendicular to the beam axis of the laser beam during the second movement along the laser path from A to B. The direction of movement of the laser beam during the second movement is thus substantially perpendicular to the beam axis of the laser beam.

[0024] According to a further advantageous embodiment of the invention, the first point A and the second point B represent the boundaries of the three-dimensional outer workpiece shape to be created in the axial direction relative to the workpiece's longitudinal axis. The laser processing extends in the axial direction between the boundaries of points A and B.

[0025] According to a further advantageous embodiment of the invention, the laser beam additionally performs a fourth movement in which the laser beam is moved in open or closed curves around a center. The fourth movement is superimposed on the second movement. The center of the fourth movement is located on the curve defined by the shape of the workpiece contour to be created. The diameter of the laser beam can be taken into account as an offset. The laser beam is thus moved according to the second movement along the workpiece contour to be created from the first point A to the second point B and is simultaneously guided according to the fourth movement along small closed or open curves.The laser beam is not only guided along a straight, curved, or irregularly shaped line that corresponds to the workpiece contour to be created, but also performs a loop-like movement around the workpiece contour to be created with the fourth movement. This allows the area in which material is removed from the workpiece when the laser beam hits the workpiece to be enlarged. The extent of the open or closed curves is small compared to the workpiece contour to be created. The closed curves can be circles, ellipses, or the shape of the number eight, for example. Open curves are characterized by the fact that the start and end points of the curve do not coincide.

[0026] According to a further advantageous embodiment of the invention, the ratio between the diameter of the open or closed curve and the diameter of the laser beam upon impact on the workpiece is between 1.2 and 150. This ensures that the extent of the open or closed curves is small compared to the workpiece contour to be created. The curve preferably has a diameter between 0.05 mm and 2.0 mm. The diameter of the laser beam upon impact on the workpiece is preferably between 0.008 mm and 0.03 mm, particularly preferably between 0.015 mm and 0.03 mm.

[0027] According to a further advantageous embodiment of the invention, during the third movement the workpiece fixing device is moved in a direction perpendicular to the beam axis of the laser beam.

[0028] According to a further advantageous embodiment of the invention, during the third movement the workpiece fixing device is moved perpendicular to the geometric longitudinal axis of the workpiece.

[0029] According to a further advantageous embodiment of the invention, during the third movement the laser beam is moved in the direction of the geometric longitudinal axis of the workpiece.

[0030] According to a further advantageous embodiment of the invention, the third movement comprises a linear movement in the radial direction relative to the workpiece longitudinal axis.

[0031] According to a further advantageous embodiment of the invention, the third movement comprises a linear movement in the axial direction or parallel to the axial direction relative to the workpiece's longitudinal axis. The third movement can comprise a superposition of a radial and an axial movement relative to the workpiece's longitudinal axis.

[0032] According to a further advantageous embodiment of the invention, the laser beam is aligned with its beam axis parallel to a radial direction relative to the geometric longitudinal axis of the workpiece when removing material from the surface of the workpiece. The feed motion of the third movement results in the focus of the laser beam being located either on the surface of the workpiece, on the workpiece contour to be created, or close to one of these points.

[0033] According to a further advantageous embodiment of the invention, the laser beam is inclined with its beam axis by an angle α in the axial direction relative to a tangent to the surface of the workpiece shape to be created, wherein the angle α is between 1° and 10°. The inclination by the angle α relative to the tangent can occur in any direction. The tangent to the surface, together with the beam axis, defines a plane. This plane can, for example, be perpendicular to the geometric longitudinal axis of the workpiece or parallel to the geometric longitudinal axis of the workpiece. Furthermore, the plane can have any other orientation relative to the geometric longitudinal axis of the workpiece.

[0034] According to a further advantageous embodiment of the invention, the third movement is controlled as a function of the second movement.

[0035] According to a further advantageous embodiment of the invention, the third movement is controlled as a function of the first movement.

[0036] According to a further advantageous embodiment of the invention, material removal takes place in the axial section between points A and B along the entire circumference of the workpiece.

[0037] According to a further advantageous embodiment, the workpiece rotational movement occurs at a constant speed throughout the entire material removal process. Alternatively, the rotational speed can be changed depending on the second and third movements and / or depending on the external workpiece shape to be created.

[0038] According to a further advantageous embodiment, the workpiece arranged in the workpiece fixing device is rotated at a rotational speed between 5 and 1,000 rpm. The rotational speed can remain constant throughout the entire processing or vary depending on the workpiece and / or the workpiece shape to be created. For a rotationally symmetrical workpiece, for example, a constant rotational speed between 50 and 300 rpm can be set. However, this is not mandatory. The rotational speed can also be adjusted depending on the diameter of the workpiece. With a rotationally symmetrical diameter of the workpiece, for example, the rotational speed can be lower at the beginning, as long as the laser beam does not yet touch the surface of the workpiece. As soon as the laser beam approaches the surface of the workpiece, the rotational speed can be increased.This affects the amount of material removed from the surface of the workpiece. For example, by changing and adjusting the rotational speed, it is possible to achieve the same amount of material being removed at specified time intervals, even though the diameter of the workpiece changes due to the material removal.

[0039] According to a further advantageous embodiment, during the second movement, which represents a guidance of the laser beam, the laser beam is moved at a speed between 0.05 m / s and 10 m / s.

[0040] According to a further advantageous embodiment, the third movement, in which the workpiece fixing device and / or the laser beam are moved towards each other, takes place at a speed between 0.05 mm / min and 500 mm / min.

[0041] According to a further advantageous embodiment, the direction of rotation in which the workpiece fixing device rotates is changed during laser processing of the workpiece.

[0042] The laser processing device for carrying out the method according to the invention is characterized in that it comprises a workpiece fixing device that receives and fixes the workpiece, a movement device that moves the workpiece fixing device relative to a device base, and a laser that generates a laser beam directed along a beam axis and has a laser deflection device that specifically deflects the laser beam. The movement device is designed to execute a workpiece rotation movement of a workpiece arranged in the workpiece fixing device. This movement is referred to as the first movement.The laser deflection device is designed to guide the laser beam and to move the laser beam along a predetermined laser path, wherein the laser path extends from a first point A to a second point B and the laser path is predetermined by the profile of the workpiece contour to be created. This movement is referred to as the second movement. The movement device and / or the laser perform a feed movement such that the surface of the workpiece arranged in the workpiece fixing device comes into contact with the laser beam, wherein material is removed from the surface of the workpiece with the laser beam and the predetermined outer workpiece contour is created. This feed movement is referred to as the third movement. The laser processing device is designed such that the first movement, the second movement and the third movement are carried out simultaneously and in a coordinated manner.

[0043] According to the invention, the laser processing device is equipped with a control device that controls the first movement, the second movement, and the third movement. This ensures that the three movements are coordinated with one another. If the laser beam performs an additional fourth movement, the control device advantageously also controls this fourth movement.

[0044] Further advantages and advantageous embodiments of the invention can be found in the following description, the drawings and the claims. drawing

[0045] The drawing shows exemplary embodiments of the laser-based machining of a workpiece according to the invention. They show: Figure 1 first embodiment of a laser-based machining of a workpiece, Figure 2 workpiece according to Figure 1 at the beginning of processing, Figure 3Workpiece according to Figure 1at different times of processing, Figure 4 Representation of the alignment of the laser beam during processing according to Figures 1 to 3 and representation of the direction of movement of the third movement, Figure 5Representation of an alternative alignment of the laser beam during processing according to Figures 1 to 3 and representation of the direction of movement of the third movement, Figure 6Representation of the alignment of the laser beam during processing according to Figures 4 and representation of an alternative direction of movement of the third movement, Figure 7Representation of the second and fourth movement related to the laser beam, Fig. 8Representation of the second and an alternative fourth movement related to the laser beam, Figure 9aWorkpiece in a perspective view in a relatively early state of laser processing, Figure 9bWorkpiece in the state according to Figure 9ain a front view, Figure 10aWorkpiece in a perspective view at the end of laser processing, Figure 10bWorkpiece in the state according to Figure 10a in a view from the front, Figure 11 Workpiece in perspective view and in a view from the front at different times of the laser processing, Figure 12 Workpiece and laser beam, wherein the laser beam is located at different positions along the laser path, Figure 13 Second embodiment of a laser-based processing of a workpiece, Figures 13a to 13n Workpiece and laser beam according to the second embodiment at different times of the laser processing, Figure 14 Non-inventive embodiment of a laser-based processing of a workpiece, Figure 15 Workpiece according to Figure 14 before starting laser processing, Figure 16Workpiece according to Figure 14 at the beginning of laser processing, Figure 17Workpiece according to Figure 14 during laser processing, Figure 18Workpiece according to Figure 14 after completion of laser processing, Figure 19Laser processing device in perspective view. Description of the embodiments

[0046] In the Figures 1 to 12 A first method for laser-based machining of a workpiece 4 using a laser beam 2 is shown. The workpiece 4 is initially in the form of a blank. The blank has the shape of a circular cylinder. The workpiece 4 is clamped in a workpiece fixing device of a laser machining device. The laser machining device 50 with a workpiece fixing device 51, a movement device 53 and a laser 56 is shown in Figure 19shown. The movement device ensures a movement of the workpiece fixing device relative to a fixture base 55. This movement includes, among other things, a rotation of the workpiece fixing device 51 together with the workpiece 4 or 54 held in the workpiece fixing device 51 around a geometric axis that coincides with the geometric workpiece longitudinal axis 5. The workpiece longitudinal axis 5 extends through the workpiece 4. It is therefore a workpiece-specific rotation axis. In the present case, the workpiece 4 has the shape of a circular cylinder before laser processing. This is rotationally symmetrical with respect to the geometric workpiece longitudinal axis 5. During rotation around the workpiece longitudinal axis 5, the workpiece 4 performs a continuous sequence of complete revolutions. This movement is referred to as the first movement. It is described in the Figures 2 to 6 represented by a circular arrow to the right of workpiece 4.

[0047] The laser processing is intended to create an outer workpiece shape with the workpiece contour 1 on the workpiece. In the embodiment according to Figures 1 to 12 the workpiece shape to be created is rotationally symmetrical with respect to the geometric workpiece longitudinal axis 5.

[0048] The laser beam 2 with geometric beam axis 2a is guided by the Figure 19 shown laser 56 is generated and by means of a Figure 19 The laser beam is guided along the workpiece contour 1 by the laser deflection device shown. This movement of the laser beam is referred to as the second movement. The laser path 3 is defined by the workpiece contour 1. It extends from a first point A to a second point B. The offset between the workpiece contour 1 and the laser path 3 is based on the radius of the laser beam 2 in a geometric workpiece plane 8, which is defined in the Figures 9a, 9b , 10a and 10bThis takes into account that the laser beam 2 can remove material from the workpiece 4 not only at a point in the center of the laser beam, but also in a circular area.

[0049] During laser processing, the laser beam 2 is guided several times along the laser path between points A and B until enough material has been removed from the workpiece 4 with the laser beam 2 to create the specified outer workpiece shape. The laser beam can be moved back and forth between points A and B, or the laser beam can only be guided in one direction at a time, from A to B or from B to A. The number of cycles that the laser beam 2 must be guided along the laser path 3 depends on the type and quantity of material to be removed and on the laser.

[0050] The laser is preferably a pulsed laser. The short laser pulses generate a high energy density at the surface of the workpiece without any unwanted heat input into the workpiece. The duration of the laser pulses is preferably in the picosecond or femtosecond range.

[0051] Through a feed movement, in which the workpiece fixing device and / or the laser beam are advanced, the surface of the workpiece 4 arranged in the workpiece fixing device comes into contact with the laser beam 2, whereby the laser beam 2 removes material from the surface of the workpiece 4 and creates the workpiece contour 1 step by step. This feed movement is referred to as the third movement. Figures 1 to 6 This feed movement is a linear movement of the workpiece 4 perpendicular to the geometric longitudinal axis 5 of the workpiece with the direction of movement 6. In Figure 6It is also shown that the laser path 3 is shifted in the direction of the geometric longitudinal axis 5 of the workpiece. This is a parallel shift of the laser path 3 in the direction indicated by an arrow.

[0052] The first movement, the second movement, and the third movement are executed simultaneously. They are superimposed. Material is removed from the surface of the workpiece 4 using the laser beam 2, whereby the specified workpiece shape of the workpiece 4 is created step by step. This is shown in Figure 3 In the first embodiment, the Figures 1 , 4 , 5 and 6 Laser beam 2 shown first at the point in Figure 2 shown contact point 7 with the workpiece 4. This contact point 7 coincides with the first point A of the laser path 3.

[0053] The laser beam 2 can be aligned with its beam axis 2a perpendicular to a workpiece plane 8. The workpiece plane 8 is a geometric plane that extends through the workpiece. The geometric workpiece longitudinal axis 5 runs in the workpiece plane. The workpiece plane 8 is in the Figures 9a, 9b , 10a and 10b shown. In principle, there are any number of workpiece planes that extend through the workpiece 4 and in which the workpiece longitudinal axis 5 runs. All planes that meet these conditions intersect in the workpiece longitudinal axis 5. The planes shown in the Figures 9a, 9b , 10a and 10b The workpiece plane 8 shown has the special feature that the laser beam 2 is perpendicular to this workpiece plane 8. The vertical alignment of the laser beam 2 is shown in the Figures 4 , 6 , 9a, 9b , 10a and 10bshown. If the laser beam 2 is aligned perpendicular to the workpiece plane 8, the laser beam 2 runs tangentially to the surface of the workpiece 4 during material removal. Alternatively, the laser beam 2 can be tilted by an angle α relative to this perpendicular orientation. A straight line perpendicular to the workpiece plane 8 is also referred to as a normal. The beam axis 2a of the laser beam 2 either runs perpendicular to the workpiece plane 8 or encloses an angle of maximum 10° with a normal to the workpiece plane 8. The laser beam 2 and the workpiece 4 are brought into contact with each other in such a way that the laser beam 2 is aligned tangentially to the surface of the rotating workpiece or encloses an angle of maximum 10° with the tangent to the workpiece surface. This is shown in Figure 5The illustration shows that the beam axis 2a of the laser beam 2 can be oriented in various directions relative to a tangent to the workpiece surface at the point to be machined. The laser focus 9 is advantageously located on or near the surface of the workpiece 4. Figure 5shows, by way of example, four different directions in which the laser beam 2 can be inclined with its beam axis. At angles α 1 and α 2 , the beam axis of the laser beam 2 and the tangent to the point to be machined on the surface of the workpiece 4 run in a plane that is parallel to the workpiece's longitudinal axis 5. At angles α 3 and α 4 , the beam axis of the laser beam 2 and the tangent to the point to be machined on the surface of the workpiece 4 run in a plane that is perpendicular to the workpiece's longitudinal axis 5. However, the laser beam can also be inclined by an angle α in any other direction. The angles α, α 1 , α 2 , α 3 , α 4 between the beam axis of the laser beam 2 and the tangent to the workpiece shape to be created are between 1° and 10°.

[0054] In the Figures 7 and 8An additional movement of the laser beam 2 is shown. This is referred to as the fourth movement. As it is guided along the laser path 3, the laser beam 2 is additionally moved along closed circular curves 10 or irregularly shaped curves 11.

[0055] In the Figures 9a, 9b , 10a, 10b , 11 and 12 The workpiece 4 and the laser beam 2 are shown in different views at different times during the laser processing. The illustration shows that the focus 9 of the laser beam 2 is located directly on the surface of the workpiece 4. The Figure 11 also shows the appearance of the workpiece 4 in different stages of laser processing. Figure 12 shows how the laser beam 2 is guided relative to the workpiece 4 during the second movement and moves along the predetermined laser path 3. The first representation in Figure 12shows the laser beam 2 at the first point A. The last representation in Figure 12 shows the laser beam 2 at the second point B. In this last illustration in Figure 12 Laser processing is complete. The workpiece now has the three-dimensional outer shape to be created. This outer shape to be created is also Figure 10a and in the penultimate presentation of the Figure 11 The specified outer workpiece shape has different cross-sections in different axial sections. The specified outer workpiece shape is rotationally symmetrical overall. The remaining representations in Figure 12 show the laser beam 2 at positions on the laser path 3 between points A and B.

[0056] In the Figures 9a and 10a the laser path 3 is shown as an intersection between the geometric workpiece plane 8 and the outer workpiece shape to be created.

[0057] In the Figures 13 and 13a to 13n A second embodiment of laser processing is shown. It differs from the first embodiment of the Figures 1 to 12in that the workpiece 24 has an outer workpiece shape 21 to be created, which comprises flat surfaces. After completion of the laser processing, the workpiece 24 has hexagonal cross-sections of different sizes in the processed section. The workpiece shape to be created is therefore not rotationally symmetrical. This outer workpiece shape is created by a superposition of the first movement, namely a rotation of the workpiece 24 about the geometric workpiece longitudinal axis 25, the second movement, which corresponds to a guidance of the laser beam along a laser path predetermined by the outer workpiece shape 21 to be created between the two points A and B, and the third movement in the form of a feed movement in direction 26. The laser beam 22 is aligned with its beam axis 22a perpendicular to the workpiece plane 28, in which the geometric workpiece longitudinal axis 25 runs. The workpiece plane is in Figure 13bThe two points A and B, which represent the boundaries of the workpiece contour in the axial direction, are offset in the axial direction relative to the geometric longitudinal axis 25 of the workpiece. They are also offset in the radial direction.

[0058] The Figures 13a to 13n show in an axial section of the workpiece 24 according to Figure 13 the different stages of material removal and the corresponding alignment of the laser beam 22 relative to the workpiece 24. The arrows 26 in the Figures 13c, 13e, 13g , 13i, 13k and 13mshow how the feed movement, referred to as the third movement, is coordinated with the rotational movement of the workpiece 24 about its geometric longitudinal axis 25, referred to as the first movement, and the position of the laser beam 22 along the laser path between points A and B, in order to generate the predetermined angular cross-section associated with the corresponding axial section. The workpiece shape 21 can be generated on a circular-cylindrical workpiece, as shown in Figure 1 is shown. The Figures 13b , 13d, 13f, 13h , 13j, 13I and 13n show that the orientation of the laser beam 22 relative to the workpiece plane 28 does not change during laser processing.

[0059] In the Figures 14 to 18 An embodiment of laser processing is shown which is not in accordance with the invention. It differs from the first embodiment according to Figures 1 to 12in that the laser beam 32, during material removal, is aligned with its beam axis radially to the geometric longitudinal axis 35 of the workpiece 34. The laser beam 32 is guided along the laser path 33, which is predetermined by a workpiece contour 31 of the workpiece 34 to be created. The feed movement according to the third movement occurs in direction 36. Figure 15 shows the workpiece 34 and the laser beam 32 before the laser processing begins. At this stage, the workpiece has the shape of a circular cylinder. Figure 16 Laser processing begins. The feed movement of the third movement moves the workpiece 34 toward the laser beam 32 such that the focus 39 is located in the area of ​​the workpiece contour 31 to be created. Arrow 40 represents the rotation of the workpiece 34 around the workpiece's longitudinal axis 35 according to the first movement. Figure 17shows the workpiece 34 after part of the material on the outside has already been removed. Figure 18 shows the finished workpiece at the end of laser processing.

[0060] In Figure 19The laser processing device 50 for carrying out the method is shown. The laser processing device 50 comprises a workpiece fixing device 51, which receives and fixes a workpiece 54, a movement device 53, which moves the workpiece 54 arranged in the fixing device relative to a device base 55, a laser 56, which generates a laser beam 52, and a laser deflection device 57, which guides the laser beam 52. The movement device 53 in the present case has three linear axes X, Y, Z and two rotation axes B and C. The rotation axis C ensures a rotation of the workpiece 54 arranged in the workpiece fixing device 51 about a geometric longitudinal workpiece axis, which extends through the workpiece. The laser deflection device 57 moves and guides the laser beam 52 in three different directions in space. The laser beam 52 is guided along a Figure 19The laser beam is moved relative to the workpiece 54 along a laser path (not shown). For this purpose, the laser deflection device 57 comprises several mirrors that can specifically deflect the laser beam. Furthermore, the laser deflection device is equipped with at least one lens that focuses the laser beam onto the surface of the workpiece 54. The mirrors and the lens are not shown in the drawing. Reference numbers

[0061] 1Workpiece contour to be created 2Laser beam 2aBeam axis 3Laser path 4Workpiece 5Workpiece longitudinal axis 6Direction of movement of the workpiece during the third movement 7Point of contact between laser beam and workpiece at the start of laser processing 8Workpiece plane 9Laser focus 10Closed curve during the movement of the laser beam according to the fourth movement 11Open curve during the movement of the laser beam according to the fourth movement 21Workpiece shape to be created 22Laser beam 22aBeam axis 24Workpiece 25Workpiece longitudinal axis 26Direction of the feed movement 28Geometric workpiece plane 31Workpiece contour to be created 32Laser beam 33Laser path 34Workpiece 35Workpiece longitudinal axis 36Direction of the feed movement 39Focus of the laser beam 40Rotation according to the first movement 50Laser processing device 51Workpiece fixing device 52Laser beam 53Workpiece moving device 54Workpiece 55Device base 56Laser 57Laser deflection device

Claims

1. Method for laser machining an elongated workpiece (4, 24, 54) that extends along a geometric workpiece longitudinal axis (5, 25), wherein a predetermined three-dimensional outer workpiece shape (21) with a workpiece contour (1) is produced at the elongated workpiece (4, 24, 54) by removing material through a laser beam (2, 52), wherein the workpiece contour (1) corresponds to an intersection of the three-dimensional outer workpiece shape (21) to be produced with a geometric workpiece plane (8, 28) in which the geometric workpiece longitudinal axis (5, 25) extends, wherein the workpiece contour (1) extends between a first point A and a second point B, and the points A and B are offset from one another at least in an axial direction, using a laser machining device (50) including a workpiece fixing device (51) for receiving and fixing the workpiece (4, 24, 54), a movement device (53) moving the workpiece fixing device (51) relative to a device base (55), a laser (56) generating a laser beam (2, 52) oriented along a beam axis (2a, 22a) and including a laser deflection device (57) deflecting the laser beam (2, 52) in a controlled manner, the method comprising the following steps - arranging the workpiece (4, 24, 54) in the workpiece fixing device (51) - performing the following three movements: a first movement that is a workpiece rotation movement where the workpiece fixing device (51) is driven by the workpiece movement device (53) to rotate the workpiece (4, 24, 54) arranged in the workpiece fixing device (51) about the geometric workpiece longitudinal axis (5, 25) in a continuous sequence of complete rotations, a second movement guiding the laser beam (2, 52), so that the laser beam (2, 52) is moved along a predetermined laser path (3) by the laser deflection device (57), wherein the predetermined laser path (3) corresponds to the workpiece contour (1) between the first point (A) and the second point (B) wherein the laser beam (2, 22) is oriented perpendicular relative to the geometric workpiece plane (8, 28) and encloses on angle of 10 degrees at the most with an orthogonal of the geometric workpiece plane (8, 28), wherein the laser beam (2, 52) is guided along the laser path between A and B multiple times during the second movement, a third movement that is a feed movement where the workpiece fixing device (51) and / or the laser beam (2, 52) are advanced so that the surface of the workpiece (4, 24, 54) arranged in the workpiece fixing device (51) contacts the laser beam (2, 52) so that the laser beam is oriented tangential to the surface of the workpiece (4, 24, 54) or encloses an angle of 10 degrees at the most with a tangent to the surface of the workpiece (4, 24, 54), wherein the laser beam (2, 52) removes material from the surface of the workpiece (4, 24, 54) and generates the predetermined three-dimensional outer workpiece shape (21) with the workpiece contour (1, 21), wherein the first movement, the second movement, and the third movement are performed simultaneously and parallel with one another until the predetermined workpiece shape with the workpiece contour (1) is generated at the workpiece (4, 24, 54).

2. Method according to claim 1, characterized in that the laser beam (2, 52) is guided along the laser path (3) from A to B and subsequently from B to A.

3. Method according to one of the preceding claims , characterized in that the laser beam (2, 52) is moved along the laser path (3) from A to B perpendicular to the beam axis in the second movement.

4. Method according to one of the preceding claims, characterized in that the first point A and the second point B form boundaries of the outer work piece shape (4, 24, 54) in the axial direction relative to the geometric work piece longitudinal axis (5, 25).

5. Method according to one of the preceding claims, characterized in that the laser beam (2, 52) performs an additional fourth movement, where the laser beam (2, 52) is moved about a center in open or closed curves and the fourth movement is superimposed to the second movement.

6. Method according to claim 5, characterized in that a ratio between a diameter of the open or closed curve and a diameter of the laser beam (2, 52) is between 1.2 and 150 at an impact point of the laser beam at the work piece (4, 24, 54).

7. Method according to one of the preceding claims, characterized in that the work piece fixing device (51) is moved in a direction perpendicular to the beam axis of the laser beam (2, 52) in the third movement.

8. Method according to one of the preceding claims, characterized in that the laser beam (2, 52) is moved towards the work piece (4, 24,54) in the third movement.

9. Method according to one of the preceding claims, characterized in that the third movement is a linear movement in the radial direction with reference to the geometric work piece longitudinal axis (5, 25).

10. Method according to one of the preceding claims, characterized in that the third movement includes a linear movement in the axial direction or parallel to the axial direction with reference to the geometric work piece longitudinal axis (5, 25).

11. Method according to one of the preceding claims, characterized in that a beam axis of the laser beam (2, 52) is oriented parallel to radial direction of the geometric work piece longitudinal axis (5, 25) when removing material from the surface of the work piece (4, 24).

12. Method according to one of the preceding claims, characterized in that a beam axis of the laser beam (2, 52) is inclined relative to a tangent at the surface of the work piece (4, 24, 54) by an angle α in the axial direction, wherein the angle α is between 1 degree and 10 degrees.

13. Method according to one of the preceding claims, characterized in that the third movement is controlled as a function of the second movement.

14. Method according to one of the preceding claims, characterized in that the third movement is controlled as a function of the first movement.

15. Method according to one of the preceding claims, characterized in that material is removed within an axial section between the points A and B along an entire circumference of the work piece (4, 24, 54).

16. Method according to one of the preceding claims, characterized in that a work piece rotation movement is performed with constant speed during an entire material removal.

17. A laser machining device configured to perform the method according to one of the preceding claims, characterized in that it includes a workpiece fixing device (51) for receiving and fixing the workpiece (4, 24, 54), a movement device (53) that moves the workpiece fixing device (51) relative to a device base (55) and a laser (56) which generates a laser beam (2, 22, 52) oriented along a laser beam axis (2a, 22a), and which includes a laser deflection device (57) that deflects the laser beam (2, 22, 52) in a controlled manner, wherein the movement device (53) is configured to perform a first movement that is a workpiece rotation movement where the workpiece fixing device (51) rotates endlessly the elongated workpiece (4, 24, 54) arranged in the workpiece fixing device (51) about the geometric workpiece longitudinal axis (5, 25) in a continuous sequence of complete rotations, wherein the laser deflection device (57) is configured to guide the laser beam (2, 52) in a second movement , so that the laser beam (2, 52) is moved along a predetermined laser path (3), wherein the predetermined laser path (3) extends from the first point A to the second point B and wherein the laser path (3) is defined by the workpiece contour (1) of the three dimensional outer workpiece shape (21) to be generated, wherein the workpiece movement device (53) and / or the laser (56) are configured to perform a feed movement as a third movement, so that the surface of the workpiece (4, 24, 54) arranged in the workpiece fixing device (51) contacts the laser beam (2, 52), wherein the laser beam (2, 22, 52) removes material from the surface of the workpiece (4, 24, 54) and generates the predetermined three-dimensional outer workpiece shape (21) with the workpiece contour (1), and wherein laser machining device (50) is provided with a control device which controls the first movement, the second movement and the third movement, wherein the first movement, the second movement and the third movement are performed simultaneously.