Method for measuring a cutting tool, and coordinate measuring device for carrying out the method

Abstract

The invention relates to a method and a coordinate measuring device for measuring a cutting tool (1,21) that has a cutting tool body (2, 22) and at least one cutting insert (3, 4, 5, 23) which is secured to the cutting tool body (2, 22) and has at least one cutting edge (10, 30). The coordinate measuring device has: a fixing device (51) which receives and fixes the cutting tool (1, 21), a measuring head which scans the surface of the cutting tool (1, 21) arranged in the fixing device (51) in a contacting or contactless manner, wherein the measuring head can be moved relative to the fixing device (51), and a movement device (53) which moves the cutting tool (1, 21) received in the fixing device (51) and the measuring head relative to each other. The measuring head is moved relative to the cutting tool along a movement path in order to determine the coordinates of cutting edge delimiting surfaces (11a, 12a, 31a, 32a) at specified measurement points.

Description

[0001] Title: Method for measuring a cutting tool and

[0002] Coordinate measuring device for carrying out the procedure

[0003] DESCRIPTION

[0004] The invention is based on a method for measuring a cutting tool which has a cutting tool body and at least one cutting insert fastened to the cutting tool body and having at least one cutting edge, as well as on a device for carrying out the method.

[0005] Cutting tools include machining tools for metal-cutting manufacturing processes and tools for cutting. They typically have a shank and a cutting part. The shank serves to hold the cutting tool, for example, in a machine interface in machine tools. The shank is equipped with the cutting part. The cutting part has at least one cutting edge with which the cutting tool interacts with a workpiece to be machined, thereby removing material from the workpiece. Such cutting tools include, for example, milling cutters, drills, reamers, chisels, scrapers, planes, and saws. The cutting tool can be a solid tool made entirely of a single material. Alternatively, the cutting part can also have an insert surrounding the cutting edge, whereby the insert is made of a different material than the shank.Cutting tools are subject to considerable mechanical and thermal stress at their point of use due to the forces acting on them and the resulting temperatures. These include mechanical friction, oxidation, and abrasion, as well as, especially at high machining speeds, diffusion and scaling. This leads to wear of the cutting tool in the area of ​​the cutting edge.

[0006] To improve the wear resistance of cutting tools and increase tool life, cutting tools are coated with a material around the cutting edge that is harder than the rest of the cutting tool body. For this purpose, a cutting tool with a cutting insert can either have the cutting insert coated with a hard coating, or the entire cutting insert can be made of a hard material. Examples of such hard or ultra-hard materials include diamond, such as polycrystalline diamond (PCD), single-crystal diamond, crystalline diamond, or diamond from chemical vapor deposition (CVD), amorphous carbon (diamond-like carbon DLC), cubic boron nitride (CBN), titanium, or ceramic.If the cutting insert is equipped with a coating made of hard material, this can be applied to the cutting insert using chemical vapor deposition (CVD), for example.

[0007] Cutting inserts are typically brazed directly onto the tool body for attachment. While this connection is characterized by high strength, brazing processes are not precise enough to ensure exact positioning of the cutting inserts on the cutting tool body. In addition, the cutting inserts may exhibit certain inaccuracies in their shape, length, width, depth, or possible surface curvature. These inaccuracies in the cutting inserts and inaccurate positioning of the cutting inserts on the cutting tool body result in the associated cutting tool not meeting the specified tolerances and being of poor quality. Target cutting edge data is specified for the cutting edge.These include, for example, the position of the cutting edge relative to a cutting tool-specific coordinate system, the geometry of the cutting edge, or the course of the cutting edge relative to the cutting edge-specific coordinate system. To determine whether the cutting edge of the cutting insert has these target cutting edge data after the cutting insert has been brazed onto the cutting tool body, and to determine the extent to which the actual cutting edge deviates from the target cutting edge data, real cutting edge data must be recorded. By comparing the real cutting edge data with the target cutting edge data, it is determined how much material must be removed at which point on the cutting insert so that the cutting edge meets the specified target cutting edge data within specified tolerances after material removal. The targeted material removal is carried out using a machining device.This can, for example, be equipped with a grinding wheel, a laser to generate a laser beam or with a device for electrical discharge machining (EDM).

[0008] Before the cutting inserts brazed onto the cutting tool body can be reworked using the machining fixture, the precise position of each cutting insert in three dimensions relative to the known references of the cutting tool must be determined. Furthermore, it must be determined whether the surfaces are flat or curved. If the cutting tool is designed as a rotary tool that rotates around a geometric cutting tool rotation axis during use, the geometric cutting tool rotation axis can, for example, serve as a reference. Another reference can be a top surface of the cutting tool or a bottom surface of the cutting tool.From the recorded position, orientation and shape of the cutting inserts and from the comparison of the actual cutting edge data with the target cutting edge data, the path is determined along which the material removal device must be moved relative to the cutting tool in order to achieve the material removal on the cutting inserts required for post-processing.

[0009] It is known to detect the position of the brazed cutting inserts on a cutting tool using a mechanical, electrical, or optical measuring probe or measuring head. The detection can be tactile, i.e. with contact with the surface of the cutting insert by the measuring head, or contactless. For this purpose, the measuring head is arranged on the machining device or on a coordinate measuring device. The measuring head is moved relative to the cutting tool in order to determine the coordinates of measuring points on the surface of the cutting insert. Based on the type and shape of the cutting tool and the type and number of cutting inserts on the cutting tool, the measuring head must be moved relative to the cutting tool in such a way that it detects the position of the surface relative to a reference value, such as the geometric cutting tool rotation axis, at at least three measuring points on each cutting insert. A coordinate system is defined for this purpose.The coordinates of the measuring points are determined using the measuring head. The relative movement of the measuring head in relation to the cutting tool is usually controlled using a computer, such as a CNC. The software must be created and specified by the responsible operator based on the type, number, and approximate position of the cutting inserts. While the operator can base this on technical specifications and drawings of the cutting tool, these specifications do not include the inaccuracies resulting from the brazing of the cutting inserts. The operator must therefore enter the details into the control system so that the measuring probe is moved to the measuring points of the cutting inserts. This is particularly time-consuming for cutting tools with a large number of cutting inserts. There is also a risk of errors being made when entering the details into the control system.

[0010] The invention is based on the object of providing a method and a coordinate measuring device with which the measurement of cutting inserts after soldering onto a cutting tool is facilitated, wherein the measurement is carried out automatically and a collision of the coordinate measuring device with the cutting tool is avoided.

[0011] This object is achieved by a method having the features of claim 1 and by a coordinate measuring device having the features of claim 15. The coordinate measuring device is equipped with

[0012] - a fixing device that holds and fixes the cutting tool,

[0013] - a measuring head which contacts the surface of the cutting tool arranged in the fixing device with contact or without contact, the measuring head being movable relative to the fixing device, and

[0014] - a movement device which moves the cutting tool held in the fixing device and the measuring head relative to each other.

[0015] The method is characterized by the following process steps: a) Geometric measuring head data, which includes the shape and size of the measuring head, are specified. b) The cutting tool is fixed in the fixing device. c) A three-dimensional coordinate system with a zero point and coordinate axes is defined. d) A three-dimensional surface of the cutting tool arranged in the fixing device is specified, at least in those sections of the cutting tool that include the cutting insert, whereby this surface is defined as the three-dimensional cutting tool surface. The surface can be specified in the three-dimensional coordinate system.e) Those sub-regions of the 3-dimensional cutting tool surface are determined which form a surface of the cutting insert and are arranged adjacent to the cutting edge of the cutting insert, whereby these sub-regions are defined as cutting edge boundary surfaces. f) Measuring points on the cutting edge boundary surfaces are determined. g) A movement path of the movement device for a relative movement of the measuring head and the cutting tool is determined, whereby the movement path is determined from the geometric measuring head data, the cutting edge boundary surfaces and the measuring points in such a way that during a relative movement of the measuring head and the cutting tool along the movement path, the coordinates of the cutting tool at the measuring points are recorded with the coordinate measuring device and a collision between the cutting tool and the measuring head during the relative movement is excluded.h) The measuring head is moved relative to the cutting tool along the trajectory path. i) The coordinates of the measuring points of the cutting edge boundary surfaces are recorded with respect to the coordinate system using the coordinate measuring device. j) Finally, the cutting edge boundary surfaces are adjusted to the recorded coordinates of the measuring points such that the recorded coordinates lie on the adjusted cutting edge boundary surfaces.

[0016] The measuring points are specified, for example, by specifying one or two coordinates of the measuring points, and the movement device positions the measuring head relative to this specified coordinate or these specified coordinates relative to the cutting edge boundary surface. The measuring head then detects the missing coordinate or coordinates of the cutting edge boundary surface.

[0017] The coordinates refer to a predefined coordinate system. This is advantageously a cutting-tool-specific coordinate system. This includes coordinate axes that extend through the cutting tool and a zero point in or on the cutting tool. When the cutting tool moves, the cutting-tool-specific coordinate system moves with it. Therefore, when the cutting tool moves, the coordinates of the cutting edge position and the coordinates of the cutting edge profile do not change in this cutting-tool-specific coordinate system.

[0018] In principle, the cutting insert does not only have surfaces that are part of the surface of the cutting tool and are located adjacent to the cutting edge of the cutting insert. For example, the cutting insert also includes those surfaces where the cutting insert is brazed to the cutting tool body. It is assumed that those surfaces of the cutting insert that are part of the surface of the cutting tool and that are adjacent to the cutting edge of the cutting insert are particularly important for the quality of the cutting tool, which is why inspection and reworking in this area is of particular importance. If necessary, measurements can of course also be performed on surfaces of the cutting insert that are not adjacent to the cutting edge.Typically, no measurement is performed in those sections of the cutting insert where the cutting insert is brazed to the cutting tool body, as these sections are not exposed and therefore do not directly affect the properties of the cutting edge, and machining in these sections could lead to the cutting insert becoming detached from the cutting tool body. In addition to these mounting sections and the surfaces that define the cutting edge, the cutting insert may have other surfaces where measurement can be performed.

[0019] The 3-dimensional cutting tool surface is specified in such a way that no data needs to be entered manually into the coordinate measuring device. The 3-dimensional cutting tool surface can, for example, be generated and specified using already known CAD data for the cutting tool. This CAD data can contain the surface of the cutting tool in two dimensions or in three dimensions. For example, the surface of the cutting tool body can be specified in three dimensions and the surface of the cutting insert in two dimensions. The three-dimensional surface of the cutting tool is then determined from this data. In this case, the 3-dimensional cutting tool surface corresponds to the theoretical geometric surface of the cutting tool generated from the CAD design of the cutting tool or is part of it.Alternatively, the 3-dimensional surface can be generated using a surface scanner based on the cutting tool clamped in the fixture and input into the fixture. In this case, the 3-dimensional cutting tool surface corresponds to the actual surface of the cutting tool after the cutting inserts have been brazed on. In both cases, the surface data does not need to be entered into the system manually. The process is therefore significantly less labor-intensive and less error-prone for the user.

[0020] By evaluating the 3-dimensional cutting tool surface, those subregions that form a surface of the cutting insert and are arranged adjacent to a cutting edge are determined. These subregions are characterized by having a specific orientation relative to a reference value of the cutting tool, for example, to the geometric cutting tool rotation axis, to the underside or the top side of the cutting tool. This property of the surfaces of the cutting inserts is utilized in their determination. Using the method according to the invention, the cutting edge boundary surfaces are determined regardless of how and in what manner the 3-dimensional cutting tool surface is specified. No data or information needs to be entered by the user for this purpose.

[0021] Thanks to the evaluation of the 3-dimensional cutting tool surface and the determination of the cutting edge boundary surfaces, the position, orientation, possible curvature of the surface and the length, width or depth of the cutting inserts are determined.

[0022] The cutting edge boundary surfaces determined from the 3-dimensional cutting tool surface are adapted to the coordinates obtained during probing with the measuring head. If the measuring points with the recorded coordinates already lie on the cutting edge boundary surfaces, the

[0023] Cutting edge boundary surfaces must not be changed. If the measuring points with the recorded coordinates do not lie on the cutting edge boundary surfaces, the

[0024] Cutting edge boundary surfaces are changed in such a way that the measuring points lie on the changed cutting edge boundary surfaces. From the cutting edge boundary surfaces, if necessary with adjustment using data from the probing, it can be determined, for example, how a material removal device must be moved relative to the cutting tool in order to specifically remove material from the cutting inserts. This allows the brazed cutting inserts to be reworked and the cutting tool to subsequently meet the specifications regarding the position, alignment, and course of the cutting edge and the surfaces defined by the cutting edge within certain tolerances. When determining the trajectory for the relative movement of the measuring head and cutting tool, the geometry and dimensions of the measuring head and the cutting tool are taken into account so that the relative movement is collision-free.

[0025] The following surfaces can be assigned to the cutting tool:

[0026] 1. A theoretical 3-dimensional geometric surface of the cutting tool resulting from its design; if the cutting tool is designed using CAD, the theoretical 3-dimensional geometric surface of the cutting tool can be derived from the CAD data. This surface does not include any inaccuracies resulting from the manufacturing and brazing of the cutting insert.

[0027] 2. Actual 3-dimensional surface of the cutting tool after brazing the cutting insert; This surface contains the inaccuracies resulting from the manufacturing of the cutting insert and the brazing of the cutting insert; This surface can be determined, for example, using a surface scanner that scans the entire surface of the cutting tool. By probing with a measuring head, the surface determined with the surface scanner is checked at specified measuring points. Alternatively, this surface can be checked using the data resulting from Section 1 and a subsequent probing of the surfaces of the cutting insert at specified measuring points with the measuring head. In both cases, the specified surfaces of the cutting insert are corrected such that the coordinates of the measuring points determined from the probing lie on the surfaces of the cutting inserts.The number of measuring points depends on the accuracy of the specified 3-dimensional surface. The higher the accuracy of the specified surface, the fewer measuring points are necessary. The 3-dimensional cutting tool surface according to claim 1 can be derived from the theoretical 3-dimensional surface according to item 1 or from the actual 3-dimensional surface according to item 2.

[0028] 3. Cutting edge limit surfaces determined from the 3-dimensional surface of the cutting tool: the cutting edge limit surfaces can be determined from the theoretical geometric 3-dimensional surface of the cutting tool according to Section 1 above or from the actual 3-dimensional surface of the cutting tool after brazing the cutting insert according to Section 2 above.

[0029] 4. Measurement points are determined on the cutting edge boundary surfaces. The surface of the cutting tool arranged in the fixing device is measured at these measurement points using the measuring head. This serves to adapt the theoretical cutting edge boundary surfaces to reality. The cutting edge boundary surfaces are adjusted such that the coordinates of the measurement points measured with the measuring head lie on the cutting edge boundary surfaces. This

[0030] Cutting edge limiting surfaces indicate the cutting edge

[0031] Real data.

[0032] In the method according to the invention, the 3-dimensional

[0033] The cutting tool surface is specified according to Section 1 above or Section 2 above, and the cutting edge boundary surfaces are determined from this according to Section 3 above. It is assumed that the adapted cutting edge boundary surfaces according to Section 4 correspond to the corresponding real surfaces on the cutting tool clamped in the fixing device and to be machined, and that they have the real cutting edge data. Based on these cutting edge boundary surfaces, material can be removed if necessary in order to adapt the cutting edges to the specified cutting edge target data. The data required for measuring the cutting inserts on the cutting tool is automatically determined from the cutting tool surface, without the operator having to make any manual entries and without the operator having to determine measurement data. This considerably simplifies the measurement process.Since no input errors can occur, the measurement is also more precise.

[0034] The measuring range and a device coordinate system are defined by travel axes and their guides, drives, and incremental measuring systems of the motion device. The device coordinate system does not correspond to a cutting tool-specific coordinate system. However, a transformation of the coordinates of the device coordinate system into the cutting tool-specific coordinate system is possible. A motion device with x, y, and z axes typically results in a Cartesian device coordinate system. Motion devices whose guides span a cylindrical or spherical coordinate system are also common. They operate with a combination of incremental displacement and angle sensors.

[0035] The measuring head can be equipped with both switching and measuring sensors. Switching sensors simply deliver a trigger signal when a measurement point is recorded, which initiates the readout of the length measuring systems. Measuring sensors, on the other hand, have their own internal measuring range of a few millimeters. The internally measured sensor value is superimposed with the sensor position determined by the length measuring systems.

[0036] To avoid unwanted collisions between the material removal device and the cutting tool, the geometric measuring head data, which includes the shape and size of the measuring head, are taken into account when determining the trajectory. This can be done using well-known calculation methods for collision avoidance. The specified data of the cutting tool and the measuring head are taken into account. Known calculation methods for collision avoidance can be used, for example, Minkowski addition. Other calculation methods are also possible.

[0037] According to an advantageous embodiment of the invention, the coordinate system is a cutting tool-bound coordinate system.

[0038] According to a further advantageous embodiment of the invention, the cutting tool is a rotary cutting tool, which is rotated about a geometric cutting tool rotation axis during use. The geometric cutting tool rotation axis corresponds to the axis about which the cutting tool is rotated at its later location of use. Advantageously, the cutting tool designed as a rotary tool is received in the fixing device in such a way that it is rotated about the geometric cutting tool rotation axis with the movement device. One of the coordinate axes of the coordinate system coincides with the cutting tool rotation axis.

[0039] According to a further advantageous embodiment of the invention, the orientation of the cutting edge boundary surfaces is determined relative to the geometric cutting tool rotation axis. This takes advantage of the fact that the cutting sets generally have a specific orientation relative to the geometric cutting tool rotation axis. This orientation is a prerequisite for the cutting inserts to achieve the desired material removal at the subsequent location of the cutting tool.

[0040] According to a further advantageous embodiment of the invention, the position of the cutting edge boundary surfaces is determined relative to the geometric cutting tool rotation axis. This takes advantage of the fact that the cutting sets generally have a specific position relative to the geometric cutting tool rotation axis.

[0041] According to a further advantageous embodiment of the invention, the position of the cutting edge limiting surface is determined relative to a front face of the cutting tool. If the cutting tool is designed as a rotary tool that is rotated about a cutting tool rotation axis at the point of use and that extends along the cutting tool rotation axis from a first end to a second end, the front face is preferably a surface of the cutting tool at the first end or at the second end that is perpendicular to the cutting tool rotation axis.

[0042] According to a further advantageous embodiment of the invention, the coordinates recorded at the measuring points are used to check whether the cutting edge boundary surfaces are curved or flat. For example, if it is determined that one of the cutting edge boundary surfaces has a curvature that leads to an undesirable curvature of the cutting edge, the corresponding cutting edge boundary surface can be smoothed through post-processing and converted into a flat surface, so that the cutting edge has a specified straight line. If the cutting edge boundary surfaces have a curvature according to the specification, more than three measuring points are advantageously specified.

[0043] According to a further advantageous embodiment of the invention, the cutting insert consists of an ultra-hard material such as polycrystalline diamond (PCD), cubic boron nitride (CBN), diamond from chemical vapor deposition (CVD), single-crystal diamond, or ceramic. In the case of a coating, this can be applied by CVD. Alternatively, diamond-like amorphous carbon (DLC) can also be used. According to a further advantageous embodiment of the invention, the 3-dimensional cutting tool surface is determined from the specified CAD data of the cutting tool. Through the computer-aided design and manufacture of the cutting tool with at least one cutting insert, a geometric model of the cutting tool is available as a digital data set. The CAD data contains this digital data set. The theoretical geometric 3-dimensional cutting tool surface can be determined from the CAD data by calculation.Because the CAD data originates from the geometric model, it does not include the inaccuracies resulting from the manufacturing of the cutting inserts and from the brazing of the cutting inserts onto the cutting tool body. Therefore, it does not accurately reflect reality. For this reason, it may be advantageous to determine measurement points on the surface of the cutting inserts, capture the actual cutting edge boundary surfaces by scanning the measurement points with a measuring head, and adjust the cutting edge boundary surfaces to the scanned data.

[0044] According to a further advantageous embodiment of the invention, the 3-dimensional cutting tool surface is generated using a surface scanner. The surface scanner is equipped with one or more sensors that systematically and regularly scan or measure the cutting tool. A large number of individual measurements generate an overall image of the cutting tool. The measured values ​​recorded by the sensors are converted into digital data and processed by a computer. From this data, the 3-dimensional cutting tool surface can be determined by calculation. The 3-dimensional cutting tool surface recorded with the surface scanner may very well represent the actual surface of the cutting tool.In this case, measurement points are defined on the surface of the cutting insert, and the surface is measured at these points with a measuring head to verify the quality of the surface captured by the scanner. The probing serves a control purpose. For example, if such an inspection of a surface of the cutting insert reveals that the coordinates captured with the measuring head are part of the 3-dimensional cutting tool surface captured with the surface scanner, then no further inspection of the remaining surfaces of the cutting insert may be necessary. If, however, deviations are detected, the inspection can continue.

[0045] According to a further advantageous embodiment of the invention, a grid of partial surfaces is placed over the 3-dimensional cutting tool surface. For each partial surface, the orientation relative to a reference value, for example, the geometric cutting tool rotation axis, is determined. From this, the cutting edge boundary surfaces are determined.

[0046] According to a further advantageous embodiment of the invention, the partial areas are triangles. Alternatively, the partial areas can also be quadrilaterals or other polygons.

[0047] According to a further advantageous embodiment of the invention, the orientation of any two adjacent partial surfaces is compared with each other. From this, the cutting edge boundary surfaces are determined. This takes advantage of the fact that adjacent partial surfaces with the same or a similar orientation belong to the same cutting edge boundary surface.

[0048] According to a further advantageous embodiment of the invention, the coordinates of the measuring points of the cutting edge boundary surfaces are recorded by contact with a tactile sensor of the measuring head. Such sensors are also referred to as mechanical sensors.

[0049] According to a further advantageous embodiment of the invention, the coordinates of the measuring points of the cutting edge boundary surfaces are recorded contactlessly using an optical or electrical sensor of the measuring head. According to a further advantageous embodiment of the invention, the collision-free trajectory is determined using Minkowski addition. Other methods for calculating the collision-free trajectory are also possible.

[0050] The coordinate measuring device according to the invention is characterized in that it is equipped with a control device which controls the fixing device, the measuring head and the movement device in such a way that they carry out the method according to the invention.

[0051] Further advantages and advantageous embodiments of the invention can be found in the following description, the drawings and the claims.

[0052] drawing

[0053] The drawings illustrate exemplary embodiments of the subject matter of the invention. They show:

[0054] Figure 1 shows a perspective view of a first embodiment of a cutting tool which is measured using the method according to the invention, representation based on CAD data,

[0055] Figure 2 perspective view of the cutting tool according to Figure 1 based on data obtained by means of a surface scanner, representation using triangles,

[0056] Figure 3 representation according to Figure 2 using different shades of grey, Figure 4 perspective representation of the cutting tool according to Figures 1, 2 and 3 after completion of post-processing,

[0057] Figure 5 Representation of the cutting tool according to Figure 1 , with the outer cutting tool geometry marked,

[0058] Figure 6 Representation of the cutting tool according to Figure 1 with the movement path of a measuring head,

[0059] Figure 7 Representation of the cutting tool according to Figure 1 with marking of the measuring points at which the surface of a cutting insert is touched with the measuring head,

[0060] Figure 8 Comparison of the CAD data and the data determined with the surface scanner for the cutting tool according to Figures 1 to 7,

[0061] Figure 9 perspective view of a second embodiment of a cutting tool which is measured using the method according to the invention, representation based on CAD data,

[0062] Figure 10 perspective view of the cutting tool according to Figure 9 based on data obtained by means of a surface scanner,

[0063] Figure 11 Detail from Figure 9,

[0064] Figure 12 Detail from Figure 11 ,

[0065] Figure 13 Part of the cutting tool according to Figures 9 and 10 after completion of post-processing,

[0066] Figure 14 Coordinate measuring device for implementing the method. Description of the embodiments

[0067] Figures 1 to 8 show a first cutting tool that is measured using the method according to the invention. The coordinate measuring device used to carry out the measurement is shown in Figure 14. Figures 1 and 2 show the cutting tool before measurement. Figure 1 corresponds to a representation of the CAD data of the cutting tool, which are specified by the design of the cutting tool using CAD. Figure 2 corresponds to a representation of data that was determined using a surface scanner. The cutting tool 1 comprises a cutting tool body 2, on which a total of six cutting inserts 3, 4, 5 are arranged. The cutting tool is a rotary tool that is rotated at its location of use about a geometric cutting tool rotation axis 6. The cutting tool is not shown in full in the drawing.A shank 7, which serves to hold the cutting tool 1 in a machine (not shown), is only partially shown for reasons of clarity. No cutting inserts are arranged in the part of the cutting tool not shown. Therefore, no measurement is carried out using the method in the part of the cutting tool not shown. The section of the cutting tool 1 in which the cutting inserts 3, 4, 5 are arranged on the cutting tool body 2 is defined as the 3-dimensional cutting tool surface. This 3-dimensional cutting tool surface is visible in Figures 1 and 2 at least insofar as it faces the viewer. The parts of the 3-dimensional cutting tool surface facing away from the viewer are concealed by the cutting tool body 2 in Figures 1 and 2.

[0068] The cutting inserts 3, 4, 5 are arranged offset relative to the cutting tool rotation axis. The two first cutting inserts 3 are located at one end 8 of the cutting tool. They are arranged on the cutting tool body 2 offset by 180° from one another and inclined by an angle α with respect to the cutting tool rotation axis. The two second cutting inserts 4 are arranged at a distance from the end 8 and from the two first cutting inserts 3 in the axial direction relative to the cutting tool rotation axis 6. They are mounted on the cutting tool body offset in the axial direction from the first cutting inserts 3. The angular distance between the two second cutting inserts is also 180°. The two third cutting inserts 5 are located between the two first and second cutting inserts 3, 4 in terms of their axial position and their angular position.In the drawing, only one of the two third cutting inserts 5 is visible, since the other third cutting insert 5 is covered by the cutting tool body 2.

[0069] The first, second, and third cutting inserts 3, 4, 5 are brazed onto the cutting tool body 2. After brazing, the cutting inserts 3, 4, 5 initially protrude radially outward beyond the cutting tool body 2. Figures 1 and 2 show the cutting tool after brazing of the cutting inserts 3, 4, 5. The portion protruding radially beyond the cutting tool body is clearly visible, particularly for the first cutting inserts 3 and the second cutting inserts 4.

[0070] Figure 1 shows a representation of the cutting tool 1 based on CAD data. This CAD data results from the computer-aided design of the cutting tool. It shows the 3-dimensional cutting tool surface, which includes the cutting inserts 3, 4, and 5.

[0071] Figure 2 shows a representation of the cutting tool 1, which is based on data that was determined using a surface scanner. This surface scanner is shown in Figure 14 with the reference number 59. The surface scanner records the surface of the cutting tool 1 from all sides in the sections in which the cutting inserts 3, 4, 5 are arranged. This results in the 3-dimensional cutting tool surface, which is essential for carrying out the method. According to Figure 2, the surface of the cutting tool 1 was recorded in exactly the section of the cutting tool 1 that is also shown in Figure 1 on the basis of the CAD data. The surface scanner results in a number of surface points. These are connected to one another in Figure 2 by lines such that triangles are formed.Figure 3 shows an alternative representation based on the same number of surface points as Figure 2, but instead of triangles, different gray levels are shown. The shape of cutting tool 1 is more clearly visible in this representation than in Figure 2.

[0072] Figure 4 shows the cutting tool 1 with the cutting inserts 3, 4, 5, wherein the cutting inserts meet predetermined criteria with regard to the position and profile of their cutting edges 10. These are, in particular, predetermined cutting edge target data, such as the position and profile of the cutting edge relative to the cutting tool rotation axis. The cutting inserts 3, 4, 5 protrude significantly less than the

[0073] Cutting tool body 2 extends radially outward. As an example, the second cutting insert 4 shows that the cutting edge 10 defines a first cutting edge boundary surface 11 and a second cutting edge boundary surface 12. The same applies to the first cutting inserts 3 and the third cutting inserts 5.

[0074] Figure 5 shows the cutting tool 1 according to Figures 1 and 2, wherein the outer geometry 13 of the cutting tool, which is defined by the specified course of the cutting edges 10 of the cutting inserts 3, 4, 5, is marked by a line in the area of ​​the first cutting insert 3 and the second cutting insert. The illustration thus illustrates the actual cutting edge data and the target cutting edge data. Comparing these data, it can be seen from the illustration that the area of ​​the cutting inserts 3, 4, 5 that protrudes beyond the outer geometry 13 of the cutting tool 1 must be removed.In particular, a post-machining must be carried out on a first cutting edge limiting surface 11a and / or a second cutting edge limiting surface 12a so that they correspond within tolerances with the first cutting edge limiting surface 11 and the second cutting edge limiting surface 12 according to Figure 4 and the cutting edge 10 thus has the specified profile.

[0075] In order to enable machining of the cutting inserts 3, 4, 5 in the area of ​​the cutting edge boundary surfaces 11a, 12a, the 3-dimensional surface of the cutting tool 1 is specified using the CAD data according to Figure 1 or using the data determined by the surface scanner according to Figure 2. The entirety of this specified data is referred to as the 3-dimensional cutting tool surface. From this 3-dimensional cutting tool surface, those sub-regions are determined that form a surface of a cutting insert 3, 4, 5 and are arranged adjacent to a cutting edge. These are referred to as cutting edge boundary surfaces 11a, 12a. They are obtained by comparing the orientation or position of the surfaces with the cutting tool rotation axis 6 or an end face 9 of the cutting tool. For this purpose, the 3-dimensional cutting tool surface is broken down into a grid of sub-surfaces 14.In the illustration according to Figure 2, the grid with the partial surfaces 14 corresponds to the triangles resulting from the connection of the surface points. For each partial surface 14, the orientation relative to the geometric cutting tool rotation axis 6 is determined. Alternatively or cumulatively, the orientation relative to the end face 9 of the cutting tool can also be determined for each partial surface 14. Adjacent partial surfaces 14 that have the same orientation are assigned to a common surface. Cutting edge boundary surfaces 11a, 12a are distinguished from other surfaces of the cutting tool 1 in that they have a very specific, predetermined orientation relative to the cutting tool rotation axis 6 or to the end face 9.

[0076] The cutting edge real data is determined from the cutting edge boundary surfaces. They relate to at least one property of the cutting edge, namely the cutting edge position relative to a cutting tool-specific coordinate system, the cutting edge geometry, or the cutting edge profile relative to the cutting edge-specific coordinate system.

[0077] Cutting edge target data is specified for the cutting tool, which relates to the corresponding property from the set of properties listed above: cutting edge position relative to a cutting-tool-specific coordinate system, cutting edge geometry, and cutting edge profile relative to the cutting-edge-specific coordinate system. The cutting tool shown in Figure 4 has this cutting edge target data.

[0078] The actual cutting edge data are compared with the target cutting edge data. This comparison determines whether and how much material needs to be removed from the recorded cutting edge boundary surfaces 11a, 12a so that the cutting edge 10 has the target cutting edge data and the specified profile with the specified outer geometry 13.

[0079] From the geometric measuring head data, the cutting edge boundary surfaces 11a, 12a, 31a, 32a, and the measuring points 16 shown in Figure 7, a movement path 15 is determined along which the measuring head is moved relative to the cutting tool by means of the movement device in order to determine the coordinates of the cutting edge boundary surfaces at the measuring points 16. This movement path 15 is shown in Figure 6 at the first, second, and third cutting inserts 3, 4, 5. The movement path 15 extends beyond the cutting edge boundary surfaces 11a, 12a, ensuring that the entire cutting edge surface 11a, 12a is contacted if necessary. The movement path is specified in such a way that the coordinates of all specified measuring points are recorded without the measuring head colliding with the cutting tool.

[0080] If the 3-dimensional cutting tool surface resulting from the CAD data according to Figure 1 does not sufficiently reflect reality, or if a check of the 3-dimensional cutting tool surface according to Figure 1, 2 or 3 is desired, measuring points are determined on at least one cutting edge boundary surface 11a, at which measuring points the coordinates of the cutting edge boundary surface are recorded using a coordinate measuring device. In the present case, three measuring points 16 are specified on the first cutting edge boundary surface 11a. The coordinates of the cutting edge boundary surface at these three measuring points 16 are then recorded using the coordinate measuring device. The resulting measurement data is compared with the cutting edge boundary surface 11a at these measuring points 16.In the event of a deviation, the cutting edge boundary surface 11a is corrected and adjusted accordingly so that the coordinates of the measuring points lie on the cutting edge boundary surface 11a. Such a check of the cutting edge boundary surfaces 11a, 12a can also be performed if the 3-dimensional cutting tool surface is determined using a surface scanner according to Figure 2 or 3. Since the surface scanner already captures the surface of the actual cutting tool, it is assumed that a check for control purposes is necessary in this case.

[0081] Figure 8 shows a comparison of the 3-dimensional cutting tool surface 17 determined using CAD data with the 3-dimensional cutting tool surface 18 determined using a surface scanner. In the light gray areas, the 3-dimensional cutting tool surface 18 determined using the surface scanner protrudes beyond the 3-dimensional cutting tool surface 17 determined using CAD data. In the dark gray areas, the situation is exactly the opposite.

[0082] Figures 9 to 13 show a second exemplary embodiment of a cutting tool 21 that is measured using the method according to the invention. Figures 9 and 10 show the cutting tool 21. Figure 9 corresponds to a representation of the CAD data of the cutting tool 21, which are predetermined by the design of the cutting tool using CAD. Figure 10 corresponds to a representation of data that was determined using a surface scanner. The cutting tool 21 comprises a cutting tool body 22 on which a plurality of cutting inserts 23 are arranged. The cutting tool is a rotary tool that is rotated at its location of use about a geometric cutting tool rotation axis 26.In contrast to the first embodiment of a cutting tool according to Figures 1 to 8, in the cutting tool 21 according to the second embodiment, all cutting inserts 23 are arranged at the same axial position relative to the cutting tool rotation axis 26 and with the same orientation relative to the cutting tool rotation axis 26 on the cutting tool body 22.

[0083] For each cutting insert 23 arranged on the cutting tool body 22, criteria for the course and position of a cutting edge 30 of the cutting insert 23 relative to the cutting tool rotation axis 26 of the cutting tool are specified as cutting edge target data. This specified cutting edge 30 is shown in Figure 13. The specified cutting edge 30 delimits a first cutting edge boundary surface 31 and a second cutting edge boundary surface 32. The course and position of the cutting edges 30 of all cutting inserts 23 of the cutting tool 21 predetermine an external geometry 33 of the cutting tool 21. This external geometry 33 is marked by a line in Figures 9 and 10.To carry out the method, the cutting edge boundary surfaces 31a, 32a of the cutting inserts 23 are determined from the 3-dimensional cutting tool surface of the CAD data according to Figure 9 or the data determined with a surface scanner according to Figure 10, and actual cutting edge data is derived therefrom. These are compared with specified cutting edge target data. Figures 11 and 12 show, as an example, the two cutting edge boundary surfaces 31a and 32a on a cutting insert 23. From the comparison with the specifications for the cutting edge 30, the first cutting edge boundary surface 31, and the second cutting edge boundary surface 32, it can be determined whether material removal must occur and to what extent. A machining device can be controlled based on the data determined in this way so that the corresponding material is removed and the cutting edge 30 meets the specifications shown in Figure 13.

[0084] The determination of the position and orientation of the cutting edge boundary surfaces 31a, 32a from the 3-dimensional cutting tool surface is carried out in accordance with the first embodiment according to Figures 1 to 8.

[0085] Figure 14 shows a coordinate measuring device 50 for carrying out the method. The coordinate measuring device is combined with a laser 56 for material removal. The coordinate measuring device comprises a fixing device 51 which receives and fixes a cutting tool 1, a movement device 53 which moves the cutting tool 1 arranged in the fixing device relative to a device base 55, a laser 56 which generates a laser beam 52, and a laser beam deflection device 57 which guides the laser beam 52. In the present case, the movement device 53 has three linear axes X, Y, Z and two rotation axes B and C. The rotation axis C ensures rotation of the cutting tool 1 arranged in the workpiece fixing device 51 about a geometric cutting tool rotation axis which extends through the cutting tool.

[0086] The coordinate measuring device 50 is further equipped with a surface scanner 59, which detects the surface of the cutting tool 1 arranged in the fixing device 51 and stores the resulting 3-dimensional cutting tool surface. This 3-dimensional cutting tool surface is output to the control device 58, which uses it to determine the cutting edge boundary surfaces of the cutting inserts.

[0087] The coordinate measuring device 50 is equipped with a measuring head 60 for detecting the surface of the cutting tool 1 arranged in the fixing device at the specified measuring points and assigning coordinates to a coordinate system. A check is then performed to determine whether these detected coordinates lie on the specified cutting edge boundary surface. If this is not the case, the cutting edge boundary surface is corrected so that the coordinates of the measuring points lie on the adjusted cutting edge boundary surface. The measuring head 60 is controlled and moved in such a way that a collision between the cutting tool and the measuring head is avoided. A relative movement between the cutting tool 1 and the measuring head is carried out by the movement device 53.

[0088] If the measurement of the cutting tool reveals that material needs to be removed from the cutting insert, this material removal can be performed using a laser. The laser beam deflection device 57 moves and guides the laser beam 52 in three different directions in space. The laser beam 52 is moved along a laser path (not shown) relative to the cutting tool 1. The control device 58 controls the fixing device 51, the movement device 53, and the laser beam deflection device 57 in order to selectively remove material from the cutting tool.

[0089] The control device 58 thus controls not only the movement device 53 and the measuring head 60, but also the laser 56. From the cutting edge

[0090] The material to be removed is determined using real data and the cutting edge target data. The laser and the movement device are controlled so that this material is removed specifically by the cutting inserts of cutting tool 1.

[0091] All features of the invention can be essential to the invention both individually and in any combination with one another.

[0092] Reference numbers

[0093] 1 cutting tool

[0094] 2 cutting tool bodies

[0095] 3 First cutting insert

[0096] 4 Second cutting insert

[0097] 5 Third cutting insert

[0098] 6 Cutting tool rotation axis

[0099] 7 shaft

[0100] 8 End

[0101] 9 Front side

[0102] 10 Cutting edge

[0103] 11 First cutting edge boundary surface after machining

[0104] 11 a First cutting edge boundary surface before machining

[0105] 12 Second cutting edge boundary surface after machining

[0106] 12a Second cutting edge boundary surface before machining

[0107] 13 External geometry of the cutting tool

[0108] 14 sub-area

[0109] 15 Movement path of the measuring head

[0110] 16 measuring points

[0111] 17 3-dimensional cutting tool surface determined using CAD data

[0112] 18 3-dimensional surfaces determined using a surface scanner

[0113] Cutting tool surface

[0114] 21 Cutting tool

[0115] 22 cutting tool bodies

[0116] 23 Cutting insert

[0117] 26 Cutting tool rotation axis

[0118] 30 cutting edge

[0119] 31 First cutting edge boundary surface after machining

[0120] 31 a First cutting edge boundary surface before machining

[0121] 32 Second cutting edge limit surface after machining 32a Second cutting edge limit surface before machining

[0122] 33 External geometry of the cutting tool

[0123] 50 coordinate measuring device

[0124] 51 Fixing device 52 Laser beam

[0125] 53 Movement device

[0126] 55 Fixture base

[0127] 56 lasers

[0128] 57 Laser beam deflection device 58 Control device

[0129] 59 surface scanners

[0130] 60 measuring head

Claims

CLAIMS Method for measuring a cutting tool (1, 21) which has a cutting tool body (2, 22) and at least one cutting insert (3, 4, 5, 23) fastened to the cutting tool body (2, 22) and having at least one cutting edge (10, 30), wherein the measurement is carried out using a coordinate measuring device (50) which has: - a fixing device (51) receiving and fixing the cutting tool (1, 21), - a measuring head which contacts the surface of the cutting tool (1, 21) arranged in the fixing device (51) with contact or without contact, the measuring head being movable relative to the fixing device (51), - a movement device (53) which moves the cutting tool (1, 21) accommodated in the fixing device (51) and the measuring head relative to each other, characterized by the following method steps a) Predetermining geometric measuring head data comprising the shape and size of the measuring head, b) Fixing the cutting tool (1, 21) in the fixing device (51), c) Establishing a three-dimensional coordinate system with a zero point and coordinate axes, d) Predetermining a 3-dimensional surface of the cutting tool (1, 21) arranged in the fixing device (51), at least in those sections of the cutting tool (1, 21) which comprise the cutting insert (3, 4, 5, 23), wherein this surface is defined as a 3-dimensional cutting tool surface (17, 18), e) Determining those partial regions of the 3-dimensional cutting tool surface (17, 18) which form a surface of the cutting insert (3, 4, 5, 23) and are adjacent to the cutting edge (10, 30) of the cutting insert (3, 4, 5, 23), wherein these partial areas are defined as cutting edge boundary surfaces (11a, 12a, 31a, 32a),f) determining measuring points (16) on the cutting edge boundary surfaces (11a, 12a, 31a, 32a), g) determining a movement path of the movement device for a relative movement of the measuring head and the cutting tool (1, 21), wherein the movement path is determined from the geometric measuring head data, the cutting edge boundary surfaces (11a, 12a, 31a, 32a) and the measuring points (16), such that during a relative movement of the measuring head and the cutting tool (1, 21) along the movement path, the coordinates of the cutting tool (1, 21) at the measuring points (16) are recorded with the coordinate measuring device and a collision between the cutting tool (1, 21) and the measuring head is excluded during the relative movement, h) moving the measuring head relative to the cutting tool (1, 21) along the movement path and, i) detecting the coordinates of the measuring points (16) of the cutting edge boundary surfaces (11a, 12a, 31a, 32a) with respect to the coordinate system using the coordinate measuring device, j) adapting the cutting edge boundary surfaces (11a, 12a, 31a, 32a) to the detected coordinates of the measuring points (16) such that the detected coordinates lie on the adapted cutting edge boundary surfaces.

2. Method according to claim 1, characterized in that the coordinate system is a cutting tool-bound coordinate system.

3. Method according to claim 1 or 2, characterized in that the cutting tool (1, 21) is a rotary cutting tool which, during use, is rotated about a geometric cutting tool rotation axis (6, 26) and that one of the coordinate axes of the coordinate system coincides with the cutting tool rotation axis.

4. Method according to claim 3, characterized in that the orientation of the cutting edge boundary surfaces (11a, 12a, 31a, 32a) is determined relative to the geometric cutting tool rotation axis (6, 26).

5. Method according to claim 3 or 4, characterized in that the position of the cutting edge limiting surfaces (11a, 12a, 31a, 32a) is determined relative to the geometric cutting tool rotation axis (6, 26).

6. Method according to one of the preceding claims, characterized in that the recorded coordinates of the measuring points are used to check whether the cutting edge boundary surfaces (11a, 12a, 31a, 32a) are curved or flat.

7. Method according to one of the preceding claims, characterized in that the 3-dimensional cutting tool surface (17) is determined from given CAD data of the cutting tool (1, 21).

8. Method according to one of the preceding claims, characterized in that the 3-dimensional cutting tool surface (18) is generated by means of a surface scanner (59) which scans the surface of the cutting tool.

9. Method according to one of the preceding claims, characterized in that a grid of partial surfaces (14) is placed over the 3-dimensional cutting tool surface (17, 18), that for each partial surface (14) the orientation relative to the geometric cutting tool rotation axis (6, 26) is determined, and that from this the cutting edge boundary surfaces (11a, 12a, 31a, 32a) are determined.

10. Method according to claim 9, characterized in that the partial surfaces (14) are triangles.

11. Method according to claim 9 or 10, characterized in that the alignment of two adjacent partial surfaces (14) are compared with each other, and that the cutting edge boundary surfaces (11a, 12a, 31a, 32a) are determined therefrom.

12. Method according to one of the preceding claims, characterized in that the coordinates of the measuring points (16) of the cutting edge boundary surfaces (11a, 12a, 31a, 32a) are detected by contact with a tactile sensor of the measuring head. Method according to one of claims 1 to 11, characterized in that the coordinates of the measuring points (16) of the cutting edge boundary surfaces (11a, 12a, 31a, 32a) are recorded contactlessly using an optical or electrical sensor of the measuring head. Method according to one of the preceding claims, characterized in that the collision-free movement path is determined using Minkowski addition. Coordinate measuring device for measuring a cutting tool (1, 21) comprising a cutting tool body (2, 22) and at least one cutting insert (3, 4, 5, 23) fastened to the cutting tool body (2, 22) with at least one cutting edge (10, 30), wherein the coordinate measuring device (50) comprises - a fixing device (51) receiving and fixing the cutting tool (1, 21), - a measuring head which contacts the surface of the cutting tool (1, 21) arranged in the fixing device (51) with contact or without contact, the measuring head being movable relative to the fixing device, - a movement device (53) which moves the cutting tool (1, 21) accommodated in the fixing device (51) and the measuring head relative to one another, characterized in that the coordinate measuring device (50) comprises a control device (58) which is designed to control the fixing device (51), the measuring head, and the movement device (53) such that they carry out the method according to one of the preceding claims on the cutting tool (1, 21). Coordinate measuring device according to claim 14, characterized in that it is equipped with a surface scanner (59). which grips the surface of the cutting tool (1, 21) at least in those sections of the cutting tool (1, 21) which comprise the cutting insert (3, 4, 5, 23).

17. Coordinate measuring device according to claim 15 or 16, characterized in that the measuring head comprises at least one tactile sensor which contacts the surface of the cutting insert (3, 4, 5, 23) at the measuring points (16) by contact.

18. Coordinate measuring device according to claim 15 or 16, characterized in that the measuring head comprises at least one sensor which probes the surface of the cutting insert (3, 4, 5, 23) at the measuring points without contact.

19. Coordinate measuring device according to claim 18, characterized in that the sensor is an electrical or optical sensor.

20. Coordinate measuring device according to one of claims 15 to 19, characterized in that the control device is a CNC control.

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