Manufacturing method for workpiece holders and rotationally symmetrical tools

Abstract

To provide a workpiece holder capable of measuring a position and a direction of a held workpiece.SOLUTION: A workpiece holder (3) couples a workpiece (2) provided with reference surfaces (30) to a machining device for manufacturing a rotational-symmetrical tool having at least one geometrically defined cutting edge. The workpiece holder (3) comprises: a machining portion part configured to be connectable to the machining device in a releasable rotationally fixed manner; and a clamping portion configured to receive and clamp the workpiece (2) in a releasable manner. The clamping portion of the workpiece holder (3) comprises at least one slot (40) provided at a circumference thereof and configured to provide access to the reference surfaces (30) of the clamped workpiece (2) through the slot (40).SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a workpiece holder for manufacturing a substantially symmetrically rotating (rotationally symmetric) tool such as a drill or a milling cutter, particularly a ball track milling cutter for manufacturing a ball track of a constant velocity joint. Further, the present invention relates to a method for manufacturing a rotationally symmetric tool and a machining apparatus.

Background Art

[0002] The manufacture of rotationally symmetric tools such as drills and milling cutters, for example ball track milling cutters and radius end milling cutters, is a multi-step process performed on a plurality of machining apparatuses. At least one of the steps includes accurately temporarily holding a workpiece, such as a rotationally symmetric workpiece, relative to the rotational axis of the machining apparatus and relative to a machining tool such as a grinding wheel during grinding, or at a position defined within a laser unit. The holding means for temporarily holding the workpiece during machining is known as a cause of a plurality of errors. In order to machine the workpiece from all directions, it is rotated about the rotational axis of the machining apparatus, and at this time, preferably, the rotational axis and the longitudinal axis or the central axis of the workpiece are the same. In practice, there are mounting tolerances, similar to the tolerances of a part of the holding means held by the clamping mechanism of the machining apparatus and the tolerances for clamping the workpiece by the holding means. In particular, when measuring the workpiece from the outside, the machining process must be interrupted, and the reproducibility of the clamping may cause further errors. Further, due to the influence of heat during machining, the position of the holding means relative to the clamping mechanism of the machining apparatus and the position of the holding means relative to the machine tool may change. These effects affect the reproducibility and accuracy when manufacturing a high-quality and high-precision rotationally symmetric tool.

[0003] High-precision ball track milling cutters are used to machine the running surface or track outline of bearing balls formed on the circumferential side surface of cylindrical components of homokinetic (constant-velocity) joints. A type of homokinetic joint consists of a spherical inner shell with grooves or raceways formed therein, and a similar outer shell, where each groove or raceway guides a single bearing ball. Homokinetic joints, also known as constant-velocity joints, are used particularly in the automotive sector, allowing a drive shaft to transmit power through a variable angle (angel) at a constant rotational speed without significantly increasing friction or play.

[0004] The manufacture of ball track milling cutters involves machining the workpiece with different machining equipment. For example, the mounting portion may be created with one machining equipment, and the functional portion with another machining equipment by grinding, laser, or other appropriate processing. To manufacture the functional portion of a ball track milling cutter that forms the milling head, the workpiece may not be held in a tool holder used with the milling equipment, but rather in a temporary holding means. Common efforts to avoid errors in the manufacture of ball track milling cutters and to achieve the precise shape of the functional portion include measuring the raw functional portion of the workpiece before machining, and relying on the maximum geometric accuracy of the interface between the (multiple) reference planes of the raw functional portion of the workpiece before machining and the temporary holding means. However, it is known that each interface between the machining equipment and the workpiece, and each change in the holding means, can introduce geometric errors that limit the achievable accuracy of the finished cutting tool, and consequently, the accuracy of the performance of the finished cutting tool may be limited.

[0005] Patent Document 1 (DE102005007038) discloses a tool grinding machine equipped with a workpiece spindle stock for receiving workpieces in a collector that provides inaccuracy correction. For inaccuracy correction and / or compensation, the spindle is configured to be motor-aligned so that the collet, and thus the workpiece, is perpendicular to the spindle line by mechanically changing the position of the workpiece. However, adjustments with respect to diameter are limited to correcting small inaccuracies within a limited degree of freedom.

[0006] Patent document 2 (EP2311600) describes an adjustment method for minimizing runout of a workpiece for a machine tool. The workpiece is held by a workpiece holding mechanism, and a floating mechanism transmits the rotation of the workpiece spindle to the workpiece holding mechanism, thereby enabling relative movement of the workpiece holding mechanism with respect to the workpiece spindle. The adjustment method includes a method for adjusting the runout of the rotating workpiece and a method for adjusting the rotation axis of the workpiece and the machining equipment to be horizontal. This adjustment method is complex and fragile, and is further limited to only two translational degrees of freedom. The mismatch between the clamp diameter and the machining diameter cannot be adjusted.

[0007] Tool holders are known for reversibly fixing to machining equipment and for reversibly receiving tools such as milling cutters. Such tool holders, collet chucks, or collet holders can be realized in a multi-part form. Generally, a tool holder consists of a mechanical or holding part that reversibly fixes the tool holder to the machining equipment, i.e., the spindle of the machine, and a clamping part for reversibly receiving the tool. Furthermore, the mechanical part can consist of shaped parts such as a conical part or a radial projection part that provides a contact surface with the corresponding opposing surface of the clamping mechanism of the machine. One type of tool holder known as the HSK holder (hollow shank taper) provides double contact between the tool holder and the clamping mechanism of the machining equipment. HSK holders are characterized by high repeatability and precision, fast tool changes, and minimal influence of temperature changes.

[0008] A rotationally symmetrical tool received in a tool holder may comprise at least two parts, such as a mounting or joint portion having a shaft portion, and a functional or cutting portion, such as a milling cutter head having at least one cutting edge for removing material from the workpiece being processed. Tool holders, adapters, spacers, extensions, etc., used to hold the tool, or the machine spindle itself, are configured to fit the tool mounting portion and can be modified accordingly. The mounting portion of the tool, received and securely held in the tool holder, forms an interface with the tool holder. For stability, rigidity, and dimensional accuracy, the interface between the tool and the tool holder is important. The interface can consist of a reference plane specially designed according to the specifications of the bender, for example.

[0009] The functional part of a rotationally symmetric tool, such as a milling cutter, has at least one geometrically defined cutting edge, which can be formed as the intersection line between the rake face and the flank face. Various types of milling cutters are known. For example, one type is configured as a solid tool consisting of a base body, with at least one cutting edge integrally formed with the base body. Another type is configured to form a cutting edge on a cutting tip or cutting plate made of another material, which is brazed, soldered, welded, or clamped to a base body made of another material. Preferably, the cutting tip is made of a hard material such as cubic boron nitride (CBN), polycrystalline cubic boron nitride (PCBN), or polycrystalline diamond (PCD), and preferably the base body is made of a tough material such as steel or cemented carbide. Generally, this type of milling cutter is machined to form cutting edges on individual cutting tips so as to fill a predetermined envelope surface that contributes to the final machined surface. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] German Patent Application Publication No. 102005007038 Specification [Patent Document 2] European Patent Application Publication No. 2311600 [Overview of the project] [Problems that the invention aims to solve]

[0011] One object of the present invention is to provide a workpiece holder for temporarily holding a workpiece. The workpiece holder as a holding means is used in a machining apparatus, particularly a grinding apparatus or a laser apparatus, for manufacturing at least a portion of a substantially rotationally symmetric tool, such as a shank tool or, preferably, a milling cutter such as a ball-track milling cutter, by grinding and / or laser processing. The workpiece holder is receivable and fixed by the machining apparatus and is configured to measure and adjust the position and / or orientation of the workpiece in the clamped position so as not to cause errors in the accuracy of the finished tool after machining.

[0012] Another object of the present invention is to provide a method for manufacturing such a rotationally symmetric tool, which includes a measurement step performed on a workpiece while it is held in a workpiece holder. The method provides adapting the machining process to take into account at least one of the position and orientation of the workpiece held in the workpiece holder when machining the workpiece, particularly when creating the functional part of the final rotationally symmetric tool. The method is configured to reduce runout errors due to deviations of at least one of distance and angle.

[0013] Another objective of the present invention is to generate measurement data of a clamped workpiece related to a reference plane of the workpiece, which can be used to machine the functional parts of the final rotationally symmetric tool, and in particular for the manufacture of high-precision tools such as ball-track milling cutters.

[0014] Furthermore, the present invention aims to provide a machining apparatus configured to measure a clamped workpiece and adapt the machining process based on the measurement data of the clamped workpiece, in order to manufacture a rotationally symmetrical tool from the workpiece. [Means for solving the problem]

[0015] These challenges are addressed by the independent claims. Advantageous embodiments of the present invention are disclosed in the figures and dependent claims.

[0016] These challenges are addressed by a workpiece holder that connects a workpiece with a reference plane to a machining apparatus for producing rotationally symmetrical tools. Preferably, the workpiece holder is configured to hold a substantially rotationally symmetrical workpiece to be machined by a milling cutter, i.e., a ball-track milling cutter.

[0017] The workpiece holder is configured to be connectable to a machining device in a detachable, rotatable locking manner. In particular, the workpiece holder is received by the clamping system of the machining device and can be securely clamped. The machine component can be received in an axially conical housing and configured to be secured by the clamping system or clamping mechanism of the machining device. As a result of the shape of the interface between the workpiece holder and the housing of the machining device, contact between two compatible shapes is achieved. Therefore, the workpiece holder aligns relative to the machining device with no play in the axial and radial directions, and is further detachable and rotatable locking. The configuration of the machine part of the workpiece holder achieves high repeatability and accuracy of relative positioning of the workpiece holder with respect to the machining device, i.e., relative positioning with respect to machine tools such as grinding wheels, and high-speed replacement of the workpiece holder.

[0018] The workpiece holder comprises a clamping portion configured to receive a workpiece and clamp it in a releaseable manner. The clamping portion of the workpiece holder is configured to be compatible with a mounting portion having a reference surface for the workpiece, so as to ensure that the workpiece is securely clamped, and the raw functional parts of the workpiece can be machined. The workpiece mounting portion may be machined in at least one previously performed machining process. The mounting portion may have any shape suitable for providing a retaining means, in particular a seating or bearing surface that bears the load against the compatible surface of the workpiece holder, in order to provide axial and / or radial positioning and orientation of the clamped workpiece. The workpiece mounting portion may comprise a shaft portion as a first seating surface. The shaft portion may have a conical or cylindrical shape to ensure secure seating in the workpiece holder by radial positioning. The conical or cylindrical shape may have a rounded cross-section along the entire length of the shaft portion, or alternatively, a rounded polygonal cross-section. The shaft portion may have a transition section to a radial portion configured to withstand the surface of a suitable configuration of the workpiece holder in order to ensure seating by axial positioning. This radial portion may be configured as a conical or annular ring with shoulders. The workpiece holder may be configured to provide a radial portion and a conical or cylindrical portion to accommodate the workpiece mounting portion. This clamping portion may be provided individually according to the specifications of the tool. Furthermore, the clamping end face of the shaft portion may be a screw clamp or a press clamp to securely hold the workpiece mounting portion to the workpiece holder or other holding means.

[0019] However, the mounting portion of the workpiece is not only configured to be securely fixed to the holding means, but also has a reference surface. The reference surface may be a cylindrical or conical shaft portion and at least a portion of an adjacent radial portion formed in a ring shape or tapered shape.

[0020] The workpiece holder includes a clamping section that clamps the workpiece in a releaseable rotational locking manner. The clamping section of the workpiece holder is configured to securely fix the workpiece mount by forming axial and radial interface surfaces between the workpiece holder and the workpiece mount. Thus, the workpiece holder securely holds the workpiece when manufacturing functional parts of finished rotationally symmetrical tools, such as the head portion of a milling cutter, including a ball-track milling cutter having at least one geometrically defined cutting edge for removing material.

[0021] According to the present invention, the clamp portion of the workpiece holder is provided on its periphery and includes at least one slot, preferably accessible from the outside, on the reference surface of the clamped workpiece. Here, a slot generally refers to an opening that is composed of various forms such as a hole or a groove.

[0022] In some cases, the workpiece may be clamped while mounted in the workpiece holder so that at least a portion of the mounting portion, i.e., the shaft portion, extends beyond the workpiece holder. Thus, the reference plane of the workpiece can be accessed by a measuring device for direct measurement. Alternatively, the rear of the workpiece can be clamped more precisely as an option for the laser unit. When manufacturing the functional parts of a rotationally symmetric tool by laser processing, very little force acts on the clamped workpiece. In this specific case, measurement of the reference plane of the clamped workpiece can be performed directly, not necessarily through a provided opening or slot in the workpiece holder. The generated measurement data can be used as described below, namely for tight tolerances related to dimensional, shape, and / or positional accuracy.

[0023] Since direct measurement of the clamped workpiece is possible, it is not necessary to repeat the steps of mounting the workpiece on the workpiece holder, machining the workpiece with a machining device, re-chucking the workpiece holder, and moving the workpiece holder with the clamped workpiece to an external measuring device to measure the machined workpiece until the final shape of the functional part is reached. The repeated re-chucking may cause well-known chuck errors and, in any case, causes errors in that high precision and ultra-high precision cannot be reliably achieved despite accurate tool guidance. Thus, manufacturing high-precision tools by repeating processes such as measurement, polishing, and measurement many times results in a high rejection rate and longer processing times.

[0024] To directly measure the position and orientation of the clamped workpiece, it is necessary to access the mounting part of the workpiece through a reference surface previously formed on the workpiece, that is, at least one slot provided in the circumferential part of the workpiece holder, or other openings such as holes, grooves, and recesses. The workpiece clamped in the workpiece holder is composed of a predefined reference surface created in advance. Advantageously, at least one slot is configured as an elongated slot that extends partially in the longitudinal direction of the workpiece holder, and the measuring probe of the measuring device is preferably inserted therein from the outside so that it can directly contact at least a part of the reference surface of the clamped workpiece. Measurement and probing by touching the reference surface widely assume the use of non-contact probe tips such as laser probes and electrostatic probes. Further, advantageously, at least one slot is configured such that measurement of the reference surface is performed. According to one embodiment, the measurement can be performed by an optical measuring device such as a camera or a laser system, or other measuring devices that can be built-in or mounted on the machining device. Preferably, the opening or slot is configured such that tactile measurement is performed. Thus, the measuring probe can be inserted and moved along a defined direction while contacting the reference surface.

[0025] In one embodiment, preferably, the elongated slot is configured such that at least a part of the three-dimensional measurement probe of the measuring device can be inserted therein. Also, the dimensions of at least one slot may be configured such that the measuring head of the measurement probe can be inserted with play. For example, when using a spherical measuring head, the width of at least one slot may be 0.5 mm to 1 mm larger than the diameter of the spherical measuring head. Advantageously, a plurality of slots may be provided in the circumferential portion of the workpiece holder. The number and arrangement of the slots in the circumferential portion of the workpiece holder are variable within a certain range, but preferably, the number of slots can be three or more as long as the mechanical stability of the clamping of the workpiece is not yet provided.

[0026] According to one aspect of the present invention, the workpiece holder is configured to hold the workpiece holder during the machining of the functional part of the rotationally symmetric tool.

[0027] According to one embodiment, the workpiece holder is configured to hold the workpiece while machining at least one cutting tip connected to the base body of the workpiece in order to create a geometrically defined cutting edge of the rotationally symmetric tool. Preferably, the rotationally symmetric tool is a ball track milling cutter.

[0028] Generally, one type of rotationally symmetric tool includes a base body and a cutting tip or cutting plate connected to the base body and providing at least one geometrically defined cutting edge. For example, a ball track milling cutter can be composed of a cutting tip or cutter blade made of a hard material and bonded. In order to manufacture a high-precision ball track milling cutter from a workpiece using a bonded cutting tip, at least one of a precise grinding process and a laser processing process is required to meet very high surface and dimensional requirements. In order to obtain the predetermined planar running accuracy of the finished tool, careful measurements must generally be made to correct the manufacturing tolerance of the functional part of the ball track milling cutter, which is generally too high, to the planar running accuracy required for the finished ball track milling cutter.

[0029] According to another embodiment of the present invention, the workpiece holder comprises at least one cam or notch provided on its outer diameter. This at least one cam or notch is configured to activate at least one measurement process at a predetermined position of the workpiece holder in the machining apparatus. The activation signal activates a measuring device, including a measuring probe, in particular a three-dimensional measuring probe, to insert into at least one slot and bring into direct contact with a reference plane of the workpiece held in the workpiece holder. Furthermore, the provided cam or notch can be used to position the workpiece holder relative to the machining apparatus in a clamping system. When the workpiece holder is connected to the machining apparatus, the workpiece holder is rotatable to a predetermined position about a rotation axis, such as the so-called B-axis.

[0030] According to one embodiment, the workpiece holder provides measurement of the displacement between the rotation axis of the machining apparatus and the longitudinal axis of the workpiece holder. This displacement may include the displacement of the longitudinal axis of the workpiece holder relative to the rotation axis of the machining apparatus and / or the axis of the workpiece. Since the clamped workpiece, preferably the reference plane of the clamped workpiece, is directly accessible from the outside, the positioning and orientation of the clamped workpiece can be confirmed using the relationship between the reference plane of the clamped workpiece, the reference point of the machining apparatus, and at least one of the reference axis. Furthermore, a reliable coordinate system can be generated using the measurement data, and the manufacturing of the functional parts of a rotationally symmetric tool can be performed based on it.

[0031] External direct measurement allows for the detection of deviations caused by incorrect settings in the machining equipment, workpiece holder, and workpiece. Therefore, setting errors may be corrected prior to machining, or they may be considered through adjustments to the machining process. Adjustments to the machining process may include settings related to rotation, pitch, and plane movement to prevent slight wobble in the workpiece due to axis shifts or offsets each time the workpiece rotates.

[0032] An advantage of the workpiece holder according to the present invention is that the reference plane of the clamped workpiece is accessible by a measuring probe. Measurement of the clamped workpiece may be performed to determine the displacement of at least one axis between the rotation axis of the machining equipment, particularly the B axis, and the workpiece axis, and further include the displacement between the workpiece axis and the longitudinal axis of the workpiece holder and / or the longitudinal axis of the workpiece holder and the rotation axis of the machining equipment, and can be corrected based on the measured value so that the position of the workpiece axis is corrected and fixed to a desired position relative to the rotational machine axis.

[0033] According to one embodiment of the present invention, a method is provided for manufacturing a rotationally symmetric tool having at least one geometrically defined cutting edge, using a workpiece holder according to the present invention to hold a workpiece. The workpiece provides a reference surface and preferably comprises at least one cutting tip in its raw functional portion. The method comprises the steps of: releasably rotating and fixing the workpiece holder to a clamping system of a machining apparatus; connecting the mounting portion of the workpiece to the workpiece holder; performing at least one measurement process to generate measurement data by introducing a measuring probe of a measuring device into at least one slot provided on the circumference of the workpiece holder and bringing it into contact with the reference surface of the clamped workpiece; correcting a displacement detected between the rotation axis of the machining apparatus and the axis of the workpiece; and processing the measurement data to obtain a curve of at least one geometrically defined cutting edge of the rotationally symmetric tool, relating to the reference surface of the workpiece used to manufacture a rotationally symmetric tool by a machining process.

[0034] In another embodiment of the present invention, the step of processing measurement data to obtain a geometrically defined cutting edge curve uses a predetermined envelope plane of the functional part of a rotationally symmetric tool. The measurement data may include data relating to the position of at least one connected cutting tip relative to a coordinate system, preferably data relating to the position of each of a plurality of cutting tips. The coordinate system may be related to a reference plane of the individual clamped workpiece.

[0035] For each rotationally symmetric tool, a predetermined ideal envelope plane is known. The envelope plane of a tool, such as a milling cutter, can be viewed as a combination of the regions of the individual envelope planes of each cutting edge that contribute to a predetermined final machined surface. Each individual envelope plane of a cutting edge can be generated as a plane of rotation by rotating around the machining axis. Therefore, deviations from the ideal position of the cutting edge, or the presence of runout, can generate an effective envelope plane that differs from the predetermined ideal envelope plane. By machining a geometrically defined cutting edge with each cutting tip, a machining process adapted to create an ideal cutting edge with respect to a predetermined ideal envelope surface can be generated using the measurement data determined for each cutting tip.

[0036] However, each of the multiple cutting tips will be measured individually to determine the measurement data of this cutting tip, which should be processed to calculate the ideal or effective cutting edge. The measurement process for individual cutting tips may include determining the position of the cutting tip using a measuring probe of a measuring device. Preferably, the measurement to determine the actual position of an individual cutting tip is performed even when the workpiece is precisely oriented within the workpiece holder. The measuring probe is inserted into at least one slot of the workpiece holder and determines the rough position of the cutting tip by contact or without direct contact. After determining the rough position of the cutting tip, measurements are performed by the measuring probe at different measurement points, preferably at least three measurement points, of the cutting tip. The obtained measurement data, including the actual precise position of the cutting tip, can be processed to generate or calculate a virtual plane of the actually positioned cutting tip.

[0037] The calculated shape of a geometrically defined cutting edge, particularly its curves, can be viewed as the intersection of a given ideal envelope surface and a virtual plane of the actually positioned cutting tip. By processing measurement data and calculating the intersection lines of individual cutting edges used to define the machining path that creates at least one of the geometrically defined cutting edge and, for example, its chamfer, the functional parts of cutting tools can be manufactured with high precision.

[0038] Another aspect of the present invention relates to a machining apparatus configured to manufacture a workpiece into a rotationally symmetric tool. The machining apparatus may be a commonly known multi-axis grinding apparatus comprising at least a control device or controller, a clamping system for holding a workpiece holder according to the present invention, and a measuring device adapted for performing measurements on the clamped workpiece.

[0039] To better understand the present invention and its advantages, exemplary embodiments of the invention will be described in more detail below with reference to the accompanying drawings, where the same reference numerals indicate the same parts. [Brief explanation of the drawing]

[0040] [Figure 1] Figure 1 is a schematic perspective view of a rotationally symmetric cutting tool, specifically a ball-track milling cutter. [Figure 2] Figure 2 is a schematic perspective view of a workpiece holder according to a first embodiment of the present invention. [Figure 3] Figure 3 is a schematic longitudinal cross-sectional view of a workpiece holder according to the first embodiment of the present invention and a workpiece inserted therein. [Figure 4] Figure 4 is a schematic cross-sectional view of a workpiece holder, a mounted workpiece, and a measuring probe during measurement processing according to the first embodiment of the present invention. [Figure 5] Figure 5 is a schematic side view of a ball-track milling cutter, showing the actual and ideal positions of the cutting edges of a rotationally symmetric tool with multiple geometrically defined cutting edges. [Figure 6] Figure 6 is a schematic perspective view of the components of a grinding apparatus for processing a workpiece into a cutting tool, showing a workpiece clamped to a workpiece holder according to the embodiment shown in Figure 2. [Figure 6a] Figure 6a is a detailed view of the grinding apparatus shown in Figure 6. [Modes for carrying out the invention]

[0041] Figure 1 is a perspective view of the head portion of a rotationally symmetric tool 1 having at least one geometrically defined cutting edge 10, in this case a total of four geometrically defined cutting edges 10, of which only one is shown. The multiple cutting edges 10 are arranged at equal intervals in the circumferential direction, and preferably each geometrically defined cutting edge 10 is identically designed. The cutting edges 10 are formed as the intersection lines of the rake face 10a and flank face 10b attached to each cutting edge 10, and the cutting edges 10 may also have chamfers 10c.

[0042] The rotationally symmetric tool 1 may be a ball-track milling cutter 100, which is configured to be received and held in a tool holder of a milling machine, and in particular to be clamped to the spindle of the milling machine. The rotationally symmetric tool 1 comprises a mounting portion 12, also referred to as a shaft portion, and a functional portion 14, with at least one geometrically defined cutting edge 10 in the head portion 18 of the rotationally symmetric tool 1. The head portion 18 comprises a base body 16, preferably made of steel or cemented carbide, and a plurality of geometrically defined cutting edges 10 that constitute the functional portion 14 of the tool 1. Hereinafter, the term functional portion 14 refers to the completed functional portion 14 of the tool 1, but also refers to the unprocessed functional portion 14 of the workpiece to be machined that has entered the completed functional portion 14 of the tool 1. In the embodiment shown in Figure 1, the cutting edges 10 are preferably formed on a cutting edge tip 15 connected to the base body 16 by soldering or brazing. The cutting edge 10 is made of or constructed from a hard material that can be selected from the group consisting of cubic boron nitride (CBN), polycrystalline cubic boron nitride (PCBN), and polycrystalline diamond (PCD).

[0043] The cutting edges 10 of the functional component 14 can be manufactured by removing material from connected cutting tips 15 made of a hard material by grinding, laser, or erosion. The cutting edges 10 are machined, preferably ground, from each cutting tip 15 already fixed to the base body 16. The grinding process can be performed on an automated multi-axis grinder, controlled by a control unit and according to a programmable computer program product. One of the methods of the present invention is to manufacture at least one geometrically defined cutting edge 10 having a defined cutting shape by removing material from the cutting tips 15.

[0044] The head portion 18 has a virtual central axis M that corresponds to the rotation axis of the tool 1 during the intended machining of the workpiece in the tooling device. Furthermore, the head portion 18 has a working end side 19 and a clamping end side 20 as a mounting portion 12 that faces the working end side 19 along the central axis M. The working end side 19 of the ball track milling cutter 100 shown in Figure 1 faces the workpiece intended to be machined by the milling device.

[0045] A mounting portion 12, preferably configured as a shaft, is provided at the end opposite to the working end 19 of a rotationally symmetric tool 1, preferably a ball-track milling cutter 100, i.e., the clamp end side 20. It should be noted that the mounting portion 12, including the clamp end side 20 of the tool 1, is manufactured before the functional components 14 of the tool 1 are manufactured. Thus, the mounting portion 12 of a workpiece 2 (not shown in Figure 1) corresponds to the finished tool 1. In the illustrated embodiment, the mounting portion 12 is cylindrical, but it can also be configured as conical in the direction toward the clamp end side 20. The clamp end side 20 may have an internal thread 21 that can be connected to a complementary threaded portion provided by the retaining means of the machining apparatus. The clamp end side 20 may be configured in a different form, such as having an external thread so that the clamp end side 20 can be fixed to the retaining means in a rotatably fixed manner that is secure and releasable.

[0046] The mounting portion 12, which has a shaft portion that can be integrally attached to the head portion 18 of the tool 1, has a first seating surface 23 that abuts against the end face of a retaining means (not shown) in the clamping position, facing the head portion 18. The first seating surface 23 may be configured as a radial portion integrated into the shaft portion 12, or as a conical or annular surface that provides a shoulder portion. A second seating surface 24, which is formed in a conical or cylindrical shape, is provided between the first seating surface 23 and the clamp end side 20. The conical or cylindrical second seating surface 24 and the first seating surface 23 form axial and radial interface surfaces that conform to the formed portion of the retaining means when the mounting portion 12 is inserted into and fixed in the retaining means of the machining apparatus. The conical or cylindrical second seating surface 24 and the radially formed first seating surface 23 form the reference surface 30 of the tool 1, which is described as the location of the workpiece 2 (not shown in Figure 1).

[0047] However, the manufacture of the rotationally symmetric tool 1 is a multi-step process. In the previous step, a rotationally symmetric workpiece 2 (not shown in Figure 1) having a central workpiece axis W (not shown in Figure 1) is machined to form the clamp end side 20 and the first seating surface 23 and second seating surface 24 that provide the reference surface 30, and is configured to be connectable to a holding means such as a workpiece holder 3 (not shown in Figure 1).

[0048] Figure 2 is a perspective view of a workpiece holder 3 according to one preferred embodiment. The workpiece holder 3 consists of a machined portion 31 and a clamping portion 32. According to the illustrated embodiment of the workpiece holder 3, the machined portion 31 is insertable into the clamping system of a machining apparatus (not shown in Figure 2). A rotationally symmetric workpiece 2 (not shown in Figure 2) may be mounted to the clamping portion 32 of the workpiece holder 3 in a releaseable, rotatably fixed manner. The workpiece holder 3 includes a conical or cylindrical portion 33 and a radial flange portion 34 in the machined portion 31. As shown in Figure 2, the radial flange portion 34 is positioned between the machined portion 31 and the clamping portion 32. The conical or cylindrical portion 33 extends along the longitudinal axis WH of the workpiece holder 3. In the case of the conical portion 33, the cone is inclined at a predetermined angle to assist in centering the workpiece holder 3 in the clamping system of the machining apparatus. The radial flange portion 34 is formed as a shoulder portion that provides an end face 34a perpendicular to the longitudinal axis WH of the workpiece holder 3, and may form a contact portion or support surface with the clamping system of the machining equipment when the workpiece holder 3 is clamped.

[0049] To connect the workpiece holder 3 to a machining apparatus, the clamping system may include a retraction finger or split collet having a clamping surface structured and positioned to engage with the inner surface of the workpiece holder 3. The retraction finger is radially extruded outward to clamp, for example, a hollow shank workpiece holder 3 with the clamping system of the machining apparatus. The hollow shank workpiece holder 3 may be designed as a known hollow shank tool holder, HSK.

[0050] As shown in Figure 2, the workpiece holder 3 is equipped with a cam 36 that protrudes from the outer diameter 35a at the outer diameter 35a. Furthermore, in the illustrated embodiment, a notch 37 is provided at the second circumferential diameter 35b. When the workpiece holder 3 is received and securely connected by the clamping system of the machining equipment in a rotatable locking manner that can be released, not only the workpiece holder 3 but also at least one of the cam 36 and the notch 37 is rotatable about the longitudinal axis WH of the workpiece holder 3. At a predetermined position, at least one of the cam 36 and the notch 37 triggers the movement of the measuring device 50 (not shown in Figure 2), which consists of a measuring probe 51 (not shown in Figure 2), from a stationary position to a measuring position. At the measuring position, the measuring probe 51 directly contacts the reference surface 30 of the clamped workpiece 2. The movement of the measuring probe 51 can be controlled by a control unit (not shown in Figure 2).

[0051] As shown in Figure 2, the workpiece holder 3 has a series of slots 40 arranged circumferentially in the clamp portion 32, which are preferably evenly spaced circumferentially and of the same design. Each slot 40 extends parallel to the longitudinal axis WH of the workpiece holder 3 for a predetermined length from the end of the clamp portion 32a toward the machining portion 31. In a preferred embodiment, each slot 40 has a width 41 sufficient to allow the passage of a measuring probe 51 to contact a portion of the clamped workpiece 2, particularly to directly access the reference surface 30 of the workpiece 2. The number and arrangement of the slots 40 may vary, but preferably there are at least three slots 40, which are evenly spaced circumferentially on the circumference of the workpiece holder 3.

[0052] Figure 3 is a schematic longitudinal cross-sectional view of the workpiece holder 3, showing the workpiece 2 inserted and clamped by the clamp portion 32 of the workpiece holder 3. The machined portion 31 of the workpiece holder 3 is configured to have an opening 31a at its end, which is configured and positioned to receive a component of the clamping system of the machining apparatus. The workpiece 2, having a reference surface 30, in particular a first seating surface 23 extending radially with respect to the central workpiece axis W and a second seating surface 24 extending axially, is inserted into the workpiece holder 3 such that the first seating surface 23 and the second seating surface 24 each form an interface with a complementaryly formed surface of the workpiece holder 3. Thus, the workpiece holder 3 provides the clamp portion 32 with radial portions and conical or cylindrical portions that are at least partially complementary to the first seating surface 23 and the second seating surface 24 of the workpiece 2, so as to provide secure seating of the workpiece 2 within the workpiece holder 3. Note that in Figure 3, the radial portion and the conical or cylindrical portion of the workpiece holder 3 are not visible.

[0053] The workpiece 2 is fixed within the workpiece holder 3 by fixing means 38 provided in the workpiece holder 3. The fixing means 38 may be configured to include a screw that can be connected to a screw formed on the clamp end 20 of the workpiece 2.

[0054] Figure 4 is a longitudinal cross-sectional view of a workpiece holder 3 equipped with a measuring probe 51 and a workpiece 2 that has been inserted and clamped. As can be seen from Figure 4, the workpiece 2 is positioned axially and radially within the workpiece holder 3 such that the longitudinal axis WH of the workpiece holder 3 coincides with the central axis W of the workpiece 2.

[0055] By initiating a measurement process performed in a manner controlled by the measuring device 50, the measuring probe 51 (preferably a three-dimensional measuring probe with a spherical measuring head) is moved from a stationary position to a measurement position. At one of the measurement positions, the measuring probe 51 is partially inserted into at least one slot 40 provided in the workpiece holder 3, and is configured to partially pass through it and make direct contact with the reference surface 30 of the clamped workpiece 2. The inserted measuring probe 51 not only contacts the reference surface 30 but also moves along the reference surface 30, enabling measurement in different directions and orientations. Different measurement points 52 are shown, and multiple measurement points 52 may be located on the reference surface 30, particularly on the first seating surface 23 and the second seating surface 24 of the workpiece 2, and multiple measurement points 52 may be located at different positions on the unmachined functional part 14 of the workpiece 2, particularly on the cutting tip 15.

[0056] By measuring at different (multiple) measurement points 52, at least one of the virtual plane of the actually positioned cutting tip and the virtual center of the central workpiece axis W of the clamped workpiece 2 can be calculated from the measurement data. To ensure the correct orientation of the workpiece 2 clamped to the workpiece holder 3, the rotation of the workpiece 2 around the axis of the machining equipment may be simulated and monitored by an inserted measurement probe 51, as well as calculated by a control device. Furthermore, by measuring the cutting tip 15 at at least three measurement points 52, the actual position of the cutting tip 15 can be determined. This measurement data can be used to calculate an ideally shaped, positioned, and geometrically defined cutting edge 10, and to manufacture this geometrically defined cutting edge 10 by grinding or laser.

[0057] Figure 5 is a schematic side view of a ball track milling cutter 100, showing the actual position 60 of the cutting tip 15 and / or cutting edge 10 and the ideal position 70 of the cutting tip 15 and / or cutting edge 10. The actual position 60 of the cutting tip 15 can be seen as a result of the process of connecting the cutting tip 15 to the base body 16, for example by soldering or brazing, as well as the original shape of the connected cutting tip 15. According to one embodiment, the geometrically defined cutting edge 10 is preferably generated on the cutting tip 15 after the cutting tip 15 is connected to the base body 16. The cutting tip 15 connected to the base body 16 usually has a circular or elliptical shape and, due to the ideal shape of the geometrically defined cutting edge 10, provides sufficient material to be removed.

[0058] The cutting edge 10 can be manufactured by a method according to the present invention, which includes measuring the actual position 60 of the cutting chip 15. This method can be controlled by a control device on which a computer program product is executed, or by another computing device configured to control a machining device such as a grinding machine and operably connected to the machining device. The machining device preferably comprises a control unit or computing device that executes a computer program and a data storage device.

[0059] Figure 6 is a schematic perspective view showing components of a machining apparatus 200, particularly a grinding machine equipped with a grinding wheel 201. The grinding machine 200 includes, in particular, a clamping system 202 that receives and clamps a workpiece holder 3. The workpiece holder 3 is configured to be releasably rotatably fixed to the grinding apparatus 200, particularly to the clamping system 202. The workpiece 2 is inserted into and held in the workpiece holder 3. Furthermore, a measuring device 50 is positioned so that a measuring probe 51 of the measuring device 50 can move from a stationary position (illustrated) to a measuring position, and the measuring probe 51 is partially inserted through at least one slot 40 or opening provided in the workpiece holder 3. At least one slot 40 is provided so that the measuring probe 51 can contact a reference surface 30 provided in the workpiece 2, which is at least partially covered by the workpiece holder 3. As shown in Figure 6, the machining apparatus 200 includes a control unit 210 configured to control not only the performance of the machining apparatus 200 but also the measurement process of the measuring device 50. The central axis W of the workpiece 2 and the longitudinal axis WH of the workpiece holder 3 coincide with the rotation axis M of the machine device 200. Small deviations in the axes can be measured by the measuring probe 51 and examined by processing the measurement data according to the method described.

[0060] Figure 6a shows details of the hold of the workpiece 2 clamped in the workpiece holder 3. The slots 40 provided in the workpiece holder 3 are arranged and configured so that the reference surface 30 can be measured even if at least a portion of the reference surface 30 is covered by the workpiece holder 3. This application offers, for example, the following perspectives. [Perspective 1] A workpiece holder (3) for connecting a workpiece (2) having a reference surface (30) to a machining apparatus (200) for manufacturing a rotationally symmetric tool (1) having at least one geometrically defined cutting edge (10), A machining unit (31) configured to be connectable to a machining device (200) using a releaseable rotational locking method, A workpiece holder (3) includes a clamping section (32) configured to receive a workpiece (2) and clamp it in a releaseable rotational locking manner, A workpiece holder (3) is characterized in that the clamp portion (32) of the workpiece holder (3) is provided on its periphery and comprises at least one slot (40) configured to provide access to the reference plane (30) of the clamped workpiece (2). [Perspective 2] The workpiece holder (3) according to viewpoint 1, characterized in that the clamp portion (32) of the workpiece holder (3) comprises a conical or cylindrical portion and a radial flange portion configured to form an interface between the clamped workpiece and a complementaryly formed reference surface (30). [Perspective 3] The workpiece holder (3) according to viewpoint 1 or 2, characterized in that at least one slot (40) is configured as an elongated slot (40) that partially extends in the direction of the longitudinal axis (WH) of the workpiece holder (3), and is configured such that a measuring probe (51) of a measuring device (50) can be inserted therein so as to directly contact at least a portion of the reference surface (30). [Perspective 4] A workpiece holder (3) according to viewpoint 1 or 2, characterized in that at least one slot (40) is configured to allow non-contact measurement of a reference surface (30) by an optical measuring device (50). [Perspective 5] A workpiece holder (3) according to any one of viewpoints 1 to 4, characterized in that it is provided with multiple slots (40). [Perspective 6] The workpiece holder (3) according to any one of viewpoints 1 to 5, characterized in that the workpiece holder (3) is configured to hold the workpiece (2) when machining the functional part (14) of the rotationally symmetric tool (1). [perspective 7] The workpiece holder (3) according to any one of views 1 to 6, characterized in that the workpiece holder (3) is configured to hold the workpiece (2) while machining at least one cutting tip (15) connected to the base body (16) of the workpiece (2) in order to form a geometrically defined cutting edge (10) of a rotationally symmetric tool (1). [Perspective 8] A workpiece holder (3) according to any one of viewpoints 1 to 7, characterized in that the rotationally symmetric tool (1) is a ball track milling cutter (100). [Perspective 9] A workpiece holder (3) according to any one of viewpoints 1 to 8, characterized in that the workpiece holder (3) comprises at least one cam (36) located on its first circumferential diameter (35a) and at least one of the cam (36) and the notch (37) is configured to activate at least one measurement process at a predetermined position of the workpiece holder (3) in a machining apparatus (200). [Perspective 10] The workpiece holder (3) according to viewpoint 9, characterized in that it measures the displacement between the rotation axis (M) of the machining apparatus (200) and the workpiece axis (W). [Perspective 11] A method for manufacturing a rotationally symmetric tool (1) having at least one geometrically defined cutting edge (10) using a workpiece holder (3) described in any one of viewpoints 1 to 10, for coupling a workpiece (2) having a reference surface (30) to a machining apparatus (200), wherein the method is as follows: - The step of connecting the machined portion (31) of the workpiece holder (3) to the clamping system (202) of the machining device (200) in a releasable rotational locking manner. - A step of connecting the mounting portion (12) of the workpiece (2) to the clamp portion (32) of the workpiece holder (3) in a releasable, rotatable, and fixed manner. - A step of generating measurement data of a clamped workpiece (2) by performing at least one measurement process and introducing the measurement probe (51) of the measuring device (50) into at least one slot (40) provided on the circumference of the workpiece holder (3) and bringing it into contact with the reference surface (30) of the clamped workpiece (2), - A step of processing measurement data to determine the actual orientation of the workpiece axis (W), The process involves processing measurement data to obtain the actual orientation of the workpiece axis (W) in order to correct the displacement detected between the rotation axis of the machining equipment and the workpiece axis (W), and - To manufacture a rotationally symmetric tool (1) by machining, the process involves processing measurement data to obtain the curve of at least one geometrically defined cutting edge (10) of the rotationally symmetric tool (1) relative to the reference plane (30) of the workpiece (2), and A manufacturing method that includes the following features. [Perspective 12] The method according to viewpoint 11, characterized in that processing the measurement data includes calculating a virtual plane of the actually positioned cutting tip (15) of the workpiece (2), and using the virtual plane of the actually positioned cutting tip (15), obtaining at least one geometrically defined cutting edge (10) curve as the intersection line between a predetermined envelope plane of the functional part (14) of a rotationally symmetric tool (1) and the virtual plane of the actually positioned cutting tip (15) of the workpiece (2). [Perspective 13] A machining apparatus (200) for manufacturing a rotationally symmetric tool (1) by the method described in viewpoint 11 or 12, - Control unit (210), - Machining tools such as grinding wheels (201), - A clamping system (202) configured to receive a workpiece holder (3) as described in any of viewpoints 1 to 10 and to connect it in a releasable, rotatable, and fixed manner, - A measuring device (50) comprising a measuring probe (51) configured to be inserted through at least one slot (40) provided on the circumference of a workpiece holder (3) in order to directly measure the reference surface (30) of a clamped workpiece (2) and A machining apparatus (200) equipped with the following. [Perspective 14] The machining apparatus (200) according to viewpoint 13, characterized in that the machining apparatus (200) is a multi-axis grinding apparatus.

Claims

1. A workpiece holder (3) for connecting a workpiece (2) having a reference surface (30) to a machining apparatus (200) for manufacturing a rotationally symmetric tool (1) having at least one geometrically defined cutting edge (10), A machining unit (31) configured to be connectable to the machining device (200) in a releaseable rotational locking manner, A workpiece holder (3) comprises a clamping portion (32) configured to receive the workpiece (2) and clamp it in a releaseable rotational locking manner, The clamp portion (32) of the workpiece holder (3) is provided with at least one slot (40) on its periphery, configured to provide access to the reference surface (30) of the clamped workpiece (2), The at least one slot (40) is configured as an elongated slot (40) that partially extends in the direction of the longitudinal axis (WH) of the workpiece holder (3), and is configured so that the measuring probe (51) of the measuring device (50) can be inserted therein so as to directly contact at least a portion of the reference surface (30). A workpiece holder (3) characterized by the following.

2. The workpiece holder (3) according to claim 1, wherein the clamp portion (32) of the workpiece holder (3) comprises a conical or cylindrical portion and a radial flange portion configured to form an interface between the clamped workpiece and the complementaryly formed reference surface (30).

3. The workpiece holder (3) according to claim 1 or 2, characterized in that a plurality of the aforementioned slots (40) are provided.

4. The workpiece holder (3) according to any one of claims 1 to 3, characterized in that the workpiece holder (3) is configured to hold the workpiece (2) when machining the functional part (14) of the rotationally symmetric tool (1).

5. The workpiece holder (3) according to any one of claims 1 to 4, characterized in that the workpiece holder (3) is configured to hold the workpiece (2) while machining at least one cutting tip (15) connected to the base body (16) of the workpiece (2) in order to form a geometrically defined cutting edge (10) of the rotationally symmetric tool (1).

6. The workpiece holder (3) according to any one of claims 1 to 5, characterized in that the rotationally symmetric tool (1) is a ball track milling cutter (100).

7. The workpiece holder (3) according to any one of claims 1 to 6, wherein the workpiece holder (3) comprises at least one cam (36) located on its first circumferential diameter (35a) and at least one of the cam (36) and the notch (37) is configured to activate at least one measurement process at a predetermined position of the workpiece holder (3) in the machining apparatus (200).

8. A method for manufacturing a rotationally symmetric tool (1) having at least one geometrically defined cutting edge (10), using a workpiece holder (3) according to any one of claims 1 to 7, for coupling a workpiece (2) having a reference surface (30) to a machining apparatus (200), wherein the method is as follows: - The step of connecting the machined portion (31) of the workpiece holder (3) to the clamping system (202) of the machining device (200) in a releasable rotational locking manner. - The step of connecting the mounting portion (12) of the workpiece (2) to the clamp portion (32) of the workpiece holder (3) in a releasable, rotatable, and fixed manner. - A step of generating measurement data of the clamped workpiece (2) by performing at least one measurement process and introducing the measurement probe (51) of the measuring device (50) into at least one slot (40) provided on the circumference of the workpiece holder (3) and bringing it into contact with the reference surface (30) of the clamped workpiece (2), - A step of processing measurement data to determine the actual orientation of the workpiece axis (W), The process involves processing measurement data to obtain the actual orientation of the workpiece axis (W) in order to correct the displacement detected between the rotation axis (M) of the machining equipment and the workpiece axis (W), and - To manufacture a rotationally symmetric tool (1) by machining, the process involves processing measurement data to obtain the curve of at least one geometrically defined cutting edge (10) of the rotationally symmetric tool (1) relative to the reference plane (30) of the workpiece (2), and A manufacturing method that includes the following features.

9. The method according to claim 8, characterized in that processing the measurement data includes calculating a virtual plane of the actually positioned cutting tip (15) of the workpiece (2), and using the virtual plane of the actually positioned cutting tip (15) to obtain at least one geometrically defined cutting edge (10) curve as the intersection line of a predetermined envelope surface of the functional part (14) of the rotationally symmetric tool (1) and the virtual plane of the actually positioned cutting tip (15) of the workpiece (2).

10. A machining apparatus (200) for manufacturing a rotationally symmetric tool (1) by the method described in claim 8 or 9, - Control unit (210), - Machining tools such as grinding wheels (201), - A clamp system (202) configured to receive and connect a workpiece holder (3) according to any one of claims 1 to 7 in a releaseable, rotatable, and fixed manner, - A measuring device (50) comprising a measuring probe (51) configured to be inserted through at least one slot (40) provided on the circumference of the workpiece holder (3) in order to directly measure the reference surface (30) of the clamped workpiece (2) and A machining apparatus (200) equipped with the following.

11. The machining apparatus (200) according to claim 10, characterized in that the machining apparatus (200) is a multi-axis grinding apparatus.

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