Process to produce a workpiece surface on a rod-shaped workpiece

Abstract

A process to produce a workpiece surface or a groove inner surface on a rod-shaped, especially cylindrical workpiece. From the workpiece, a rotary tool is supposed to be produced. The material removal is done using laser beam pulses, which are directed through a deflection device onto points of incidence within a pulse area with a specified outside contour on the workpiece. Multiple machine axis drives position the workpiece and the deflection device relative to one another so that the pulse area is oriented essentially at right angles to the emission direction of the laser beam pulses and at right angles to the section of the tool surface that has already been produced and that borders the pulse area. While the material is being removed, the at least one machine axis drive moves the pulse area relative to the workpiece along a specified path of motion while maintaining the orientation.

Claims

1. A process to produce a workpiece surface (23) comprising a groove inner surface (25) of a groove (24) on a rod-shaped workpiece (11) using a machining machine (10) that has a laser (12) that produces laser beam pulses (B), with a laser head (13) that directs the laser beam pulses (B) of the laser (12) onto the workpiece (11), and with a machine drive unit (16) that has at least one machine axis drive (18) that is configured to move the workpiece (11) and the laser head (13) relative to one another in at least one translational and/or rotational degree of freedom (X, Y, Z, DX, DY, DZ), with the following steps: Positioning and/or orienting the workpiece (11) relative to the laser head (13); Specifying and/or selecting a pulse area (22) having an outside contour (K) and points of incidence (31) arranged within the pulse area (22) that are separated from one another, onto which the laser beam pulses (B) from the laser head (13) are emitted in a specified sequence, the outside contour (K) of the pulse area (22) defining a cross-sectional contour to be removed in order to produce the groove inner surface (25) of the groove (24); Emitting the laser beam pulses (B) through the laser head (13) in an emission direction (R) onto the specified points of incidence (31) within the pulse area (22) on the workpiece (11), wherein, during the machining, the laser beam pulses (B) being oriented tangential to the section of the groove inner surface (25) that is produced by the machining of the workpiece (11) and that borders the pulse area (22); Moving the laser head (13) and/or the workpiece (11) relative to one another in such a way that the pulse area (22) on which the material removal takes place is moved with respect to the workpiece (11) following a specified path of motion (38) exclusively in the emission direction (R) to produce the groove inner surface (25).

2. Process according to claim 1, characterized in that all workpiece areas adjacent to the groove inner surface (25) that is produced on which laser beam pulses (B) impinge during machining are already completely removed by the production of the groove inner surface (25) and while machining it is taking place.

3. The process according to claim 1, characterized in that the laser beam pulses (B) that are directed onto the points of incidence (31) of the pulse area (22), are oriented tangential at least to the adjacent, already produced section of the groove inner surface (25), and reduce the roughness of this adjacent section of the groove inner surface (25).

4. The process according to claim 1, characterized in that the outside contour (K) of the pulse area (22) is changed depending on the current relative position and/or relative orientation of the workpiece (11) with respect to the laser head (13).

5. The process according to claim 1, characterized in that the workpiece (11) has at least two workpiece sections (41) that have different absorption characteristics for the laser light that is used and that the groove inner surface (25) is produced by a continuous process sequence in the two workpiece sections (41).

6. The process according to claim 5, characterized in that the two workpiece sections (41) consist of parts (42, 43) that are connected with one another by material bonding.

7. The process according to claim 1, characterized in that the distance between immediately adjacent points of incidence (31) in the pulse area (22) remains constant during the production of the groove inner surface (25).

8. The process according to claim 1, characterized in that the groove (24) being produced starting from a first groove end (36).

9. The process according to claim 8, characterized in that the groove (24) has, opposite the first groove end (36), a second groove end (37) that is produced last of all.

10. The process according to claim 9, characterized in that the groove depth decreases in the area of the second groove end (37).

11. The process according to claim 9, characterized in that the outside contour (K) of the pulse area (22) when the second groove end (37) is produced is different from the outside contour (K) of the pulse area (22) when the first groove end (36) is produced.

12. The process according to claim 1, characterized in that energy input of the laser beam pulses (B) per unit area is larger or smaller in an edge zone (33) of the pulse area (22) that borders the groove inner surface (25) that is being produced or that has been produced than in a core zone (34) of the pulse area (22) that is separated from the groove inner surface (25) that is being produced or that has been produced.

13. The process according to claim 1, characterized in that the process produces a tool (40) from the workpiece (11).

14. A process to produce a sharp edge on one edge of a groove inner surface (25) of a workpiece (11), characterized in that first a surface is produced on the workpiece (11) that has an oversize at least around the edge, and then this oversize is removed according to the process according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Advantageous embodiments of the process follow from the dependent claims, the description, and the drawing. Preferred sample embodiments of the process are explained below on the basis of the attached drawing. The figures are as follows:

(2) FIG. 1 is a schematic representation of a machining machine that is designed to perform the inventive process;

(3) FIG. 2 is a schematic perspective representation of a rod-shaped workpiece during the production of a workpiece surface;

(4) FIG. 3 is a schematic perspective representation of a rod-shaped workpiece during machining in which the outside contour of a pulse area specified for the machining is illustrated;

(5) FIGS. 4 and 5 are each schematic top views of an example of a pulse area;

(6) FIG. 6 is a tool produced from a rod-shaped workpiece using the inventive process; and

(7) FIG. 7 is a schematic longitudinal section through an example of a workpiece on which a workpiece surface is to be produced, showing its contour and the outside contour of the pulse area which changes during production of the workpiece surface.

DETAILED DESCRIPTION OF THE PARTICULAR EMBODIMENTS

(8) FIG. 1 schematically illustrates a machining machine 10, which is designed to perform an inventive process to machine a rod-shaped workpiece 11. The unmachined workpiece 11 has a cylindrical shape; according to the example it is circular cylindrical. Machining the workpiece 11 with machining machine 10 produces a rotary tool that rotates about the longitudinal axis A of the workpiece 11 or the tool produced from it.

(9) The machining machine 10 has a pulsed laser 12 that produces a pulsed laser beam, that is laser beam pulses B. The pulsed laser beam is sent from laser 12 to a laser head 13. The laser head 13 is designed to emit the laser beam pulses B in a specified direction with respect to its optical axis O, and focus them in a machining area. While the workpiece 11 is being machined, the currently machined surface of the workpiece 11, that is the material removal site or the material removal surface, is located within the machining area.

(10) The laser head 13 can have focusing means, such as optical lenses or means of that kind. This gives the laser beam pulse B a divergence angle , which is schematically illustrated in FIG. 1. The divergence angle in the far field is, so to speak, the aperture angle of the laser beam pulse from the focusing means of the laser head 13 to the machining area. The laser head 13 also has a deflection device 14, which can also be referred to as a laser scanner. The deflection device 14 can have, for example, one or more deflection mirrors, and it serves to adjust the exit direction of the laser beam pulses B with respect to the optical axis O.

(11) The machining machine 10 has a control unit 15 to control the laser 12 and the laser head 13.

(12) The control unit 15 also controls a machine drive unit 16 of the machining machine 10. The machine drive unit 16 is designed to produce a relative motion between the laser head 13 and a tensioning device 17 to tension the rod-shaped workpiece 11 in the machining machine 10. The machine drive unit 16 produces a relative motion between the tensioned workpiece 11 and the laser head 13.

(13) To orient and/or position and/or move the tensioning device 17 relative to the laser head 13 or vice versa, the machine drive unit 16 has one machine axis drive 18 for each translational degree of freedom X, Y, Z that is present and for each rotational degree of freedom DX, DY, DZ that is present; FIG. 1 only very schematically illustrates part of the machine axis drives 18. The number of the translational and/or rotational degrees of freedom X, Y, Z, DX, DY, DZ can vary, it being possible to provide a total of up to six degrees of freedom.

(14) Alternatively to the representation in FIG. 1, the laser head 13 can also be moved through one or more machine axis drives 18 in one degree of freedom for each drive. The only decisive thing is the relative motion of the workpiece 11 or the tensioning device 17 with respect to the laser head 13.

(15) The laser beam pulses B are directed in an emission direction R from the laser head 13 onto the workpiece 11. The area of the workpiece surface onto which the laser beam pulses B impinge and in which material removal takes place is defined by a pulse area 22. The pulse area 22 is produced by the deflection device 14.

(16) Examples of the pulse area 22 can be seen especially in FIGS. 3 through 5. The pulse area 22 has an outside contour K. The outside contour K is selected or specified in such a way that the outside contour K matches, that of, a workpiece surface 23 to be produced.

(17) In the sample embodiment described here, the workpiece 11 has at least one groove 24 produced on it that has a groove inner surface 25. The groove inner surface 25 is the entire surface resulting during production of the groove 24. That is, in this case, the workpiece surface 23 to be produced is formed by the groove inner surface 25. In the sample embodiment, the groove to be produced 24 is shaped like a channel at every point when viewed in cross section. In the sample embodiment, the two groove edges 26 at which the groove 24 merges into the original outside surface 27, have the same radial distance from the longitudinal axis A. The groove to be produced 24 can run straight in the direction of the longitudinal axis A oras illustrated herebe in the shape of a spiral around the longitudinal axis A. For example, it can be a groove for chips on the tool 40 to be produced from the workpiece 11.

(18) Alternatively to the described groove 24, it is also possible to use the machining machine 10 and the inventive process to produce, on the workpiece 11, other surfaces, for example flanks or rake faces bordering a cutting edge.

(19) The outside contour K of the pulse area 22 corresponds to a material cross section that borders the workpiece surface 23 to be produced and is supposed to be removed from workpiece 11. Thus, in the sample embodiment described here, the outside contour K of the pulse area 22 corresponds to the groove cross section of the groove 24 to be produced. According to the example, the outside contour K has a first outside contour section K1, which directly borders the cross-sectional surface 23 to be produced, that is here the groove inner surface 25 during the workpiece machining. The outside contour K also has a second outside contour section K2 that corresponds, at least in for instance one cross sectional contour section, to the original workpiece cross sectional contour (the original outside surface 27 of the workpiece) during the machining of the workpiece 11. In the sample embodiment, both outside contour sections K1, K2 are curved and abut one another, forming two corners. Depending on the geometry to be produced, according to the example the groove geometry, it is also possible for the outside contours K to have straight sections, or to have combinations of straight or curved sections.

(20) Multiple points of incidence 31 are located within the outside contour surface K. The points of incidence 31 are arranged distributed within the outside contour K. The distance between directly adjacent points of incidence 31 can be uniform within the pulse area 22 or vary. This depends first on the geometry of the outside contour K and second on whether the energy input per unit area within the pulse area 22 should be uniform or irregular. For every outside contour K the control unit 15 can have a defined arrangement of the points of incidence 31 specified and/or stored in it. The control unit 15 controls the deflection device 14 during the machining of the workpiece 11 in such a way that the laser beam pulses B during a sequence are directed onto the points of incidence 31 within the outside contour K in a specified order. After the end of a sequence, at least one laser beam pulse is directed onto every point of incidence 31. This sequence is cyclically repeated. For example, the laser beam pulses can be moved along a pulse path 32 from one point of incidence 31 to the next point of incidence 31. FIGS. 4 and 5 schematically illustrate two sample embodiments of such pulse paths 32. The pulse path 32 according to FIG. 4 meanders within the pulse area 22, while the pulse path 32 has a spiral-shaped course, for example. Other pulse paths 32 or sequences or orders deviating from this to direct the laser beam pulses B onto the points of incidence 31 are possible.

(21) The pulse area 22 can have an edge zone 33 that is drawn in dashed lines in FIGS. 4 and 5. The edge zone 33 borders on the first outside contour section K1. The surface sections of the pulse area 22 not belonging to the edge zone 33 form a core zone 34 that is thus separated from the first outside contour section K1. In the sample embodiment, the energy input per unit area in the edge zone 33 can be smaller than in the core zone 34 of the pulse area 22. At least the energy input per area of the laser beam pulses directed onto the points of incidence 31 in the edge zone 33 is smaller than a specified maximum value. This ensures that when material is removed during the machining of the workpiece 11, too great an energy input in the area of the edge zone 33 does not produce any heat-affected zone on the workpiece surface 23 to be produced or the groove inner surface 25. Such a heat-affected zone can make the material of the workpiece 11 brittle and therefore require a finishing of the workpiece surface 23 that is produced. By contrast, the core zone 34 is sufficiently separated from the first outside contour section K1 and consequently from the material areas of the workpiece 11, which later form the workpiece surface 23, that in the core zone 34 the energy input per unit area can be selected to be greater than in the edge zone 33.

(22) The energy input per unit area can be varied, for example, by, changing the density of the points of incidence within the pulse area 22, that is within the edge zone 33 or the core zone 34. Alternatively or additionally, parameters of the laser 12 can also be changed, for example the duration of a laser beam pulse B and/or the laser power.

(23) The process to produce the tool surface 23 using the machining machine 10 is as follows:

(24) The machine drive unit 16 is used to put the unmachined workpiece 11 in an initial position with respect to the laser head 13. During the process, the control unit 15 controls the machine drive unit 16 to move and/or orient the workpiece 11 relative to the laser head 13. The sequence of motions is specified, and especially programmed in the control unit 15. The suitable process sequences for a certain workpiece type can be called from a library, for example. Depending on the workpiece surface or workpiece geometry to be produced, the control unit 15 also controls the laser head 13 or the deflection device 14 during the process, to adjust the outside contour K of the pulse area 22 associated with each current relative position between the workpiece 11 and the laser head 13. The outside contour K can remain constant during the process, or change. A changing outside contour K can only be carried out in a scaling of the area while maintaining the geometric shape of the outside contour K. Alternatively or additionally, it is also possible for the geometric shape of the outside contour K to be changed.

(25) In the sample embodiment described here, a groove 24 is produced in the original cylindrical workpiece 11. In the area of the face 34 at a free end 35 of the workpiece 11, the groove 24 has a first groove end 36 and, separated from it, an opposite second groove end 37. The groove 24 is produced starting from the free end 35 of the workpiece, so that the first groove end 36 is produced first. Then, the groove 24 is lengthened along the direction of its course starting from the first groove end 36 by material removal, until the second groove end 37 is finally finished.

(26) The machine drive unit 16 always adjusts the distance of the workpiece 11 from the laser head 13 so that the currently machined site of the workpiece 11 lies within the focused working range of the laser beam pulses B. The workpiece 11 is oriented with respect to the emission direction R in such a way that the laser beam pulses B impinge on the workpiece 11 parallel or tangential to the section of the workpiece surface 23 or groove inner surface 25 that is arranged immediately adjacent to the material removal site, that is to the pulse area 22, in the direction opposite the emission direction R. In other words, in a section adjacent to the pulse area 22 or to the points of incidence 31, the laser beam pulses B run tangential to an already produced surface section of the workpiece surface 23 or groove inner surface 25 that directly abuts the pulse area 22. Tangential means that the angle between the direction of propagation or the longitudinal central axis of a laser beam pulse B and a tangent touching the surface section of the workpiece surface 23 that is produced directly bordering the material removal site is smaller than the divergence angle or is smaller than half the divergence angle .

(27) The pulse area 22 during the machining is specified in such a way that it is always located in a cross sectional plane of the groove 24. During the machining, the pulse area 22 is moved through the workpiece 11 in the direction in which the groove 24 runs, so to speak, starting from the first groove end 36 all the way to the second groove end 37, until the groove 24 has been completely produced. The relative motion required for this is produced by one or more machine axis drives 18 in the corresponding degrees of freedom X, Y, Z, DX, DY, DZ.

(28) At every point in time, the outside contour K of the pulse area 22 can correspond to the cross sectional contour of the groove 24 to be produced. In this case, there is no displacement of the pulse area within a plane in which the pulse area 22 extends. Instead, the pulse area 22 is moved in its normal direction relative to the workpiece 11, and consequently in the emission direction R. Alternatively, it is also possible to select the outside contour K of the pulse area to be smaller in at least one dimension than the cross sectional contour to be produced of the groove 24. In this case, the pulse area is additionally moved or shifted in the cross sectional plane of the groove 24, to achieve the desired cross sectional contour of the groove 24.

(29) While the material is being removed, the relative orientation or relative motion of the workpiece 11 with respect to the laser head 13 moves the pulse area 22, so to speak, along a specified path of motion 38 (FIG. 2) relative to the workpiece 11, according to the example from the first groove end 36 to the second groove end 37.

(30) The result is that the areas of the workpiece 11 on which the laser beam pulses B impinge are completely removed already during, and due to the production of the workpiece surface 23 or the groove inner surface 25. Areas of the surface on which the laser beam pulses B impinge are, as a rule, too rough after production or have been affected by the energy input, that is, the heat. Frequently, the material of the workpiece is brittle there. To remove such a heat-affected zone and/or reduce the roughness, frequently finishing is then done. In the process proposed here this can be dropped. At the material removal site the produced workpiece surface 23 is always oriented essentially at right angles to the pulse area 22, so that where the laser beam pulses B impinge, the bordering workpiece surface 23 that has already been produced is smoothed. If smaller areas there should project into the clear space profile of the pulse area 22, they are removed by the laser beam pulses directed onto the pulse area 22, and the already produced workpiece surface 23 obtains very low roughness. Thus, the workpiece surface 23 can be produced in one pass while the material is being removed.

(31) FIG. 6 illustrates an example of a tool 40 that is being produced in which multiple grooves 24 are being produced. According to the example, the grooves 24 there are arranged in the shape of a spiral around the longitudinal axis A. While these grooves 24 were being produced, the outside contour K of the pulse area 22 was changed to achieve different groove cross sections at different axial positions relative to the longitudinal axis A of the tool 40. The groove depth and also the groove width decrease starting from the first groove end 36 to the second groove end 37. The respective adjusted outside contour K of the pulse area 22 is schematically illustrated at various axial positions. The channel shape of the groove 24 and consequently of the outside contour K of the pulse area 22 remains the same. At the second groove end 37, the groove inner surface 25 that is produced merges into the original outside surface 27 of the unmachined workpiece 11.

(32) Such a process can very advantageously be used to machine workpieces 11 that have two or more workpiece sections 41 that are made of different materials or that have different absorption characteristics for the laser light that is used. Such a workpiece 11 is illustrated in a very strongly schematized manner and only as an example in FIG. 2. There, the one workpiece section 41 is formed, for example, by a hard metal shaft 42 that has an end piece 43 that forms the other workpiece section 41. The end piece 43 can consist, for example, of a very durable, hard material, such as, for example, diamond. It goes without saying that the workpiece 11 could also have more than two workpiece sections 41.

(33) The two workpiece sections 41 can be arranged axially one after the other in the direction of the longitudinal axis A, as illustrated in FIG. 2. Alternatively or additionally, the two workpiece sections 41 could also be arranged one after the other radial to the longitudinal axis A. In other words, they can cross over or overlap in the axial direction and/or in the radial direction. It is also possible to make at least one workpiece section 41 by coating another workpiece section 41.

(34) In the example described here, the two workpiece sections 41 and, according to the example, the hard metal shaft 42 and the end piece 43, are connected with one another, preferably by material bonding. The materially bonded connection can be produced by an adhesive or by soldering. The two workpiece sections 41 can have a connection layer between them that is made of an adhesive or solder.

(35) The fact that the workpiece surface 23 to be produced is produced by laser beam pulses B that are always incident tangential to the workpiece surface 23 to be produced (relative to the material removal site) also allows the material removal to be continuous or uninterrupted through the various workpiece sections 41 with different absorption characteristics. Although the removal rate can vary depending on the absorption characteristics of the respective workpiece section 41, the quality and especially the roughness of the workpiece surface 23 that is produced remains unaffected by this. Thus, it is possible to produce, for example, tools with a hard metal shaft 42 and a tool tip made from the end piece 43, the workpiece surfaces or the grooves 24 that are produced running through both the end piece 43 and also the hard metal shaft 42, as is schematically illustrated in FIG. 2.

(36) In another sample embodiment of the process, in addition to, or as an alternative to the change in the outside contour K according to FIG. 6, it is also possible to change the geometric shape of the outside contour K, which is very schematically illustrated in FIG. 7. There, for example, a curved area of the workpiece surface 23 to be produced is produced using a circular outside contour K of the pulse area 22, while a polygonal, according to the example quadrilateral, in particular rectangular or square shape of the outside contour K is used to produce a corner in an end area of the tool surface 23 to be produced. Using such adaptation of the geometry of the outside contour K it is possible, for example, to produce a groove 24 whose second groove end 37 can have edges and/or corners and/or steps on the tool 40.

(37) The invention relates to a process to produce a workpiece surface 23 or a groove inner surface 25 on a rod-shaped, especially cylindrical workpiece 11. From the workpiece 11, a rotary tool is supposed to be produced. The material removal to produce the workpiece surface 23 is done using laser beam pulses B, which are directed through a deflection device 14 onto the workpiece 11 at points of incidence 31 within a pulse area 22 having a specified outside contour K. One or more machine axis drives 18, in particular CNC axes, orient or position or move the workpiece 11 and the deflection device 14 relative to one another so that the pulse area 22 with the points of incidence 31 for the laser beam pulses B arranged within it is oriented essentially at right angles to the emission direction R of the laser beam pulses and at right angles to the already produced section of the tool surface 23 that borders the pulse area 22. While the material is being removed, the at least one machine axis drive 18 moves the pulse area 22 relative to the workpiece 11 along a specified path of motion 38 while maintaining the orientation, that is always at right angles to the immediately adjacent already produced section of the workpiece surface 22. This makes it possible, for example, to produce a groove 24 with a groove inner surface 25 in the direction in which the groove 24 runs, starting from a first groove end 36 at the free end 35 of the workpiece all the way to an opposite free groove end 37. The outside contour K of the pulse area 22 can correspond to the respective cross section to be produced of the groove 24, or at least lie within the cross section to be produced of the groove 24.

LIST OF REFERENCE NUMBERS

(38) 10 Machining machine 11 Workpiece 12 Laser 13 Laser head 14 Deflection device 15 Control unit 16 Machine drive unit 17 Tensioning device 18 Machine axis drive 22 Pulse area 23 Workpiece surface 24 Groove 25 Groove inner surface 26 Groove edge 27 Original outer surface of workpiece 31 Point of incidence 32 Pulse path 33 Edge zone 34 Face 35 Free end of workpiece 36 First groove end 37 Second groove end 38 Path of motion 40 Tool 41 Workpiece section 42 Hard metal shaft 43 End piece Divergence angle of laser beam pulses A Longitudinal axis of workpiece B Laser beam pulse DX Rotational degree of freedom DY Rotational degree of freedom DZ Rotational degree of freedom K Outside contour K1 First outside contour section K2 Second outside contour section O Optical axis of laser head R Emission direction x Translational degree of freedom y Translational degree of freedom z Translational degree of freedom