Ultra-precision lathe and method for ultra-precision forming using same

Abstract

The present invention relates to an ultra-precision lathe (1) for the ultra-precision forming of a workpiece (3), the ultra-precision lathe (1) comprising: - a spindle (7) having a workpiece receptacle (5) for receiving a workpiece (3) to be machined, the spindle (7) defining an axis of rotation (L) about which the spindle (7) can be rotated with a workpiece (3) received by means of the workpiece receptacle (5), - at least one tool (9) which can be advanced dynamically relative to the spindle (7), for removing material by cutting, and - at least one sensor for directly or indirectly determining an imbalance of the spindle (7), characterized in that the ultra-precision lathe (1) also has a balancing ring (13) which is releasably attached to the spindle (7) coaxially with respect to the axis of rotation (L), the balancing ring (13) having an inner diameter which is greater than an outer diameter of the workpiece receptacle (5), and it being possible to remove material from the balancing ring (13) rotationally asymmetrically by dynamically advancing the at least one tool (9) while the spindle (7) is rotating, in order to compensate for an imbalance determined by means of the at least one sensor by removing material from the balancing ring (13) by cutting.

Description

[0001] Applicant: InnoLite GmbH

[0002] Title: Ultra-precision lathe and method for ultra-precise shaping with it

[0003] Our reference number: INNP 3716 WO

[0004] Description

[0005]

[0001] The present disclosure relates to an ultra-precision lathe and a method for ultra-precise forming therewith. The surfaces of workpieces machined by this machine, whose shape is to be produced in this way, are intended to have a dimensional tolerance below

[0006] 5:5 pm.

[0007]

[0002] Ultra-precision lathes are used to machine workpieces by machining, resulting in a very precisely defined surface finish. The goal of ultra-precision machining with an ultra-precision lathe is to achieve a particularly high level of surface finish.

[0008] 10. Surface quality with a dimensional tolerance of less than 5 pm across the entire machined surface of the workpiece. A dimensional tolerance of less than 5 pm across the entire machined surface means that a peak-to-valley value (Rt according to DIN EN ISO 4287) of 5 pm is not exceeded across the entire machined surface.

[0009]

[0003] Such surface qualities are particularly required for special optics made of glass, glass-ceramics, or plastic. However, metallic workpieces may also require such surface qualities, for example, if they form a negative surface of a mold insert.

[0010] 20 zes for the replicative production of optical surfaces, for example in injection molding or injection compression molding processes, should be defined.

[0011] Patent Attorneys Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025

[0004] Regardless of the material of the workpiece or the material used as a tool for machining, it is essential to achieve such surface qualities by machining the ultra-precision lathe before machining the workpiece.

[0012] 5 to balance very precisely. Any imbalances of the spindle of the ultra-precision lathe, for example in the first order due to eccentricity, in the second order due to wobble, or in higher orders due to deformations or vibrations, can lead to the required dimensional tolerance below 5 m not being exceeded.

[0013] 10 velvet-finished surfaces can be achieved.

[0014]

[0005] Therefore, the spindle of an ultra-precision lathe is typically balanced in a lengthy manual adjustment procedure before each machining operation of a newly clamped workpiece. Small set screws distributed circumferentially around the spindle are used for this purpose.

[0015] 15 are manually adjusted. For fine-tuning, adhesive strips are even applied to the spindle to compensate for any imbalances. This process is iterative, meaning that after each adjustment, the change in imbalance is measured, and the spindle is readjusted until the imbalance is below a tolerable level. This process

[0016] Manual balancing is not only very time-consuming, but also requires highly experienced operators who must know a specific model of ultra-precision lathe intimately in order to reduce imbalances to an acceptable level. Due to the complexity of this manual balancing process, readjustment is generally avoided.

[0017] 25 moderately waived once material removal from the workpiece has begun.

[0018]

[0006] This results in the task of accelerating and simplifying the manual balancing process, so-

[0019] Patent attorneys Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025 that it no longer depends so much on the experience of the operating personnel and readjustment is possible if material has already been removed from the workpiece.

[0020]

[0007] According to the present invention, to solve this problem

[0021] Five lems provide an ultra-precision lathe and a method according to the independent claims. Advantageous embodiments of the invention can be found in the dependent claims, the description, and the drawings.

[0022]

[0008] According to a first aspect of the invention, an ultra-precision lathe is provided for the ultra-precise shaping of a workpiece, wherein the ultra-precision lathe comprises: a spindle with a workpiece holder for receiving a workpiece to be machined, wherein the spindle defines an axis of rotation about which the spindle rotates with a workpiece holder by means of the workpiece holder.

[0023] 15. The workpiece is rotatable, the machine comprises at least one tool that can be dynamically adjusted relative to the spindle for machining material, and at least one sensor for directly or indirectly determining an imbalance of the spindle, characterized in that the ultra-precision lathe further comprises a balancing ring that is detachably attached to the spindle coaxially to the axis of rotation, wherein the balancing ring has an inner diameter that is larger than an outer diameter of the workpiece holder, wherein the material of the balancing ring

[0024] 25 by dynamically adjusting the at least one tool while the spindle is rotating, in order to compensate for an imbalance determined by means of the at least one sensor by machining material from the balancing ring.

[0025] Patent Attorneys Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025

[0009] Optionally, the balancing ring can have at least one annular end face and the at least one tool can be configured to remove material from the at least one end face of the balancing ring in a rotationally asymmetric manner by dynamically adjusting the spindle while the spindle is rotating.

[0026] 5. This is particularly advantageous because advancing the tool in the direction of the axis of rotation is relatively easy, even if the workpiece is also being machined on its end face. The tool for material removal on the balancing ring can be the same as the one used for machining the workpiece, or a separate tool. If the balancing ring has the same

[0027] 10. If the material is the same as the workpiece, it may be advantageous to use the same balancing tool that is also intended for machining the workpiece. If the balancing ring is made of a different material than the workpiece, it may be advantageous to use a different balancing tool than the one intended for machining the workpiece.

[0028]

[0010] Optionally, the balancing ring can have at least two annular end faces in a stepped configuration, wherein the at least two annular end faces are axially spaced apart from each other. This is advantageous in order to

[0029] 20. Any second-order imbalances, such as wobbling, can be achieved by removing material from the different end faces.

[0030]

[0011] Optionally, the balancing ring can be designed in multiple parts, with each part of the balancing ring providing a material removal surface, preferably on its end face, wherein the material removal surfaces are axially spaced apart from one another. This is advantageous in order to design the balancing ring to be compact on the one hand and to achieve the largest possible axial distance between the material removal surfaces on the other, thereby effectively counteracting any second-order imbalances, for example, wobble.

[0031] 30 tiver can be balanced.

[0032] Patent Attorneys Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025

[0012] Optionally, the parts of the balancing ring can be detachably attached to the spindle with an axial distance from each other and coaxial to the axis of rotation. In principle, the greater the axial distance, the better a second-order imbalance, for example wobble, can be eliminated.

[0033] 5 are the same. However, both material removal surfaces must be located in a machine area where controlled approach of the tool to the respective material removal surface is possible quickly and easily.

[0034]

[0013] Optionally, the parts of the balancing ring can have different outer diameters. This can be advantageous so that two separate tools are not required for each part of the balancing ring, but rather all, preferably two, parts of the balancing ring can be machined for balancing with the same tool, particularly from one end face.

[0035] 15

[0014] Optionally, the at least one tool can be suitable for both machining material removal from the balancing ring and machining material removal from a workpiece held by means of the workpiece holder. As already mentioned above, this is particularly useful if the balancing ring has the same material as the

[0036] 20 workpieces.

[0037]

[0015] Optionally, the ultra-precision lathe can also have at least one additional tool that can be dynamically positioned relative to the spindle for machining the workpiece. As mentioned above, this is particularly useful if the balancing ring is not made of the same material as the workpiece.

[0038]

[0016] Optionally, the at least one tool can be configured to perform one or more operations during or between machining steps.

[0039] 30. To remove material from the balancing ring of a workpiece held by means of the workpiece holder by dynamically adjusting the feed while the spindle is rotating, in a rotationally asymmetric manner. Such readjustment is particularly useful when the workpiece is rotationally asymmetric.

[0040] Patent attorneys Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025, are involved in processing, such that an imbalance is introduced by the machining of the workpiece. Such an imbalance can be compensated for by removing material from the balancing ring during or between machining steps.

[0041] 5

[0042]

[0017] According to a second aspect of the present invention, a method is provided for ultra-precise shaping of a workpiece using an ultra-precision lathe, wherein the method comprises the following steps:

[0043] 10. Rotating a spindle of the ultra-precision lathe about a rotary axis, wherein the spindle has a workpiece holder for receiving a workpiece to be machined,

[0044] Direct or indirect determination of an imbalance of the rotated spindle by means of at least one sensor, characterized in that the method further comprises:

[0045] Balancing the turned spindle by machining material from a balancing ring which is detachably attached to the spindle coaxially to the axis of rotation and has an inner diameter larger than an outer diameter of the workpiece holder, where

[0046] 20 where the material of the balancing ring is removed by dynamically adjusting at least one tool while the spindle is rotating in a rotationally asymmetrical manner in order to compensate for an imbalance determined by means of at least one sensor by removing material from the balancing ring.

[0047]

[0018] The method according to the invention is preferably carried out on an ultra-precision lathe according to the invention.

[0048]

[0019] Optionally, the steps of rotating, determining the Un-

[0049] 30. Balancing and balancing during or between machining steps of a workpiece held by means of the workpiece holder may be carried out and / or repeated.

[0050] Patent Attorneys Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025

[0020] Optionally, the same tool can be used for machining the workpiece as for balancing. Alternatively, a separate tool that is not used for balancing can be used for machining the workpiece.

[0051] 5

[0052]

[0021] Optionally, during balancing, the material of the balancing ring can be removed by dynamically adjusting the at least one tool while the spindle is rotating, in a rotationally asymmetric manner, from an annular end face of the balancing ring.

[0053]

[0022] Optionally, when determining the imbalance, a wobbling movement of the spindle can be detected and, during balancing, material can be removed from at least two material removal surfaces of the balancing ring, wherein the at least two material removal surfaces have an axial

[0054] They should be 15 cm apart.

[0055]

[0023] Optionally, the at least two material removal surfaces can be located on different end faces of a stepped balancing ring and / or on two different parts of a multi-part balancing ring.

[0056] 20

[0057]

[0024] Optionally, the method can further include a step of smoothing the balancing ring before or after machining a workpiece held by means of the workpiece holder, wherein the balancing ring is smoothed by removing the material of the balancing ring by the at least one tool with rotating spindle until the balancing ring has a rotationally symmetrical material distribution again.

[0058]

[0025] A method according to the invention and / or an inventive device

[0059] A 30-inch ultra-precision lathe can be used to produce optical surfaces in metal for mirrors or molding tools, in infrared materials such as germanium, silicon, or zinc selenide, or directly in plastics, especially for rotationally symmetric optics. The workpiece to be machined rotates on the spindle and

[0060] Patent attorneys Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025: The tool can be moved by two interpolating linear axes in such a way that a target geometry is established on the workpiece, taking radius correction into account. Even non-rotationally symmetrical surfaces can be produced in this way by moving the tool

[0061] 5. A dynamic feed movement synchronized with the spindle rotation is superimposed on the cutting action.

[0062]

[0026] This method can even achieve dimensional accuracy of less than 100 nm over diameters of 50 mm and more with roughness

[0063] Achieving surface finishes of less than 1 nm Ra on the workpiece is possible. Numerous aspects can be considered to achieve such qualities in this machining process using a tool with a geometrically defined cutting edge, for example made of natural or synthetic monocrystalline diamond.

[0064]

[0027] For example, a monocrystalline diamond tool, if correctly oriented, can be lapped in such a way that cutting edge radii of only 50 nm are set for particularly high cutting performance. The tool geometry can have a radius

[0065] 20, where particular attention is paid to a minimal remaining waviness.

[0066]

[0028] First and foremost, the material of the workpiece to be machined should exhibit a high degree of homogeneity. Grain boundaries in metals, impurities, or voids can limit the quality of the result.

[0067]

[0029] Data for surface description and routines for calculating machine programs should have a sufficiently high resolution. This applies both to program calculations that determine the rotational speed

[0068] 30 digkeits of the spindle and the feed movements of the tool are determined, as well as for a further processing CNC (Computer Numerical Control).

[0069] Patent Attorneys Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025

[0030] The machine itself should meet the highest accuracy standards in order to achieve the surface qualities described above. For this purpose, the ultra-precision lathe according to the invention can have mechanically non-contact linear axes with fluidic bearings (ae¬

[0070] The 5-axis linear direct drive (either erostatic or hydrostatic) features a high-resolution optical scale. The spindle can be aerostatically mounted in the bearing gap to minimize frictional resistance due to increased relative speeds. Granite can be used as the material for the machine bed to ensure low thermal expansion.

[0071] to have 10 and, due to the open porosity of the material, to lap the relevant guideways by hand to flatness below 1 m per meter.

[0072]

[0031] Furthermore, by actively controlling the temperatures of cooling water, oil in hydrostatics and / or compressed air, the temperature fluctuations can be kept in the range of a few tens of millikelvin.

[0073]

[0032] As already explained above, in addition to the workpiece material, the tool, the data and the machine parts, the balance condition

[0074] 20 when turning ultra-precise surfaces, a significant influence on the achievable surface qualities.

[0075]

[0033] An imbalance arises when masses are unequally distributed around the ideal axis of rotation of the spindle. If the center of mass of this mass distribution is not located on the axis of rotation, a centrifugal force arises according to the formula wxoxr * m, where GO is the angular velocity, r is the radius between the axis of rotation and the center of mass, and m is the eccentrically located mass. The resulting centrifugal force acts as a disturbance on the machine and affects

[0076] 30 affects the achievable precision. Due to limited mechanical rigidity in the machine structure and individual components, it can

[0077] Patent attorneys Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025, state that displacements can occur due to the disturbing force, and consequently, inaccuracies. In particular, any air gap in the preferably aerostatically mounted spindle, in which the spindle rotor can shift, must be considered. However, mechanical structural components can also cause displacements.

[0078] 5. The linear axes, the machine bed or the spindle mount can experience displacements.

[0079]

[0034] Traditionally, machine stiffnesses are given in N / pm, with the values ​​being considered across the entire machine structure.

[0080] The force from the so-called tool center point to the component is typically 20-30 N / pm on good machines. However, since in the case of ultra-precision machining considered here, stiffness-related deviations of just 50 nm can have a significant impact, even disturbance forces on the order of 1 N can lead to unacceptable quality losses.

[0081]

[0035] Furthermore, the disturbance force caused by an imbalance also affects the axis control. A position controller of the control system can, for example, receive target position values ​​from a CNC machine. The controller can then

[0082] The controller attempts to minimize the deviation between a specified target value and the actual achieved position value in 20 steps. The remaining deviation between the target and actual values ​​is called the following error. An external disturbance force, such as imbalance, is extremely difficult for the controller to compensate for. In a rest state (no spindle rotation), a well-tuned linear axis of an ultra-precision lathe can exhibit following errors of < 1 nm. Rotation of the spindle with insufficient balance can increase the following error to unacceptable values ​​of > 100 nm and more.

[0083] 30

[0036] The phenomenon of imbalance can be considered in several planes. For example, a rotor of an aerostatic spindle of an ultra-precision lathe according to the invention can have a length of 300 mm. At the front end of the rotor, the

[0084] Patent attorneys Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025. A workpiece holder, for example a clamping system, may be arranged to hold a workpiece. At the rear end of the rotor, the motor may be located with a rotary encoder for determining the angle of rotation. The imbalances at both ends of the spindle rotor can be reduced by...

[0085] 5. The absolute magnitudes of the imbalance vectors, as well as their vector orientations, can differ. A purely radial deflection observed when considering imbalance in one plane can result in rotor wobble when considering it in two planes.

[0086] 10

[0037] Balancing can preferably be performed in at least two planes spaced apart in the direction of the axis of rotation when the spindle is initially set up. The process can be iterative, since the spindle rotor may not be considered ideally stiff and there may therefore be an influence of the balancing state of the front to the back. An uneven mass distribution around the axis of rotation of the spindle may not be directly determinable as a mass with eccentricity. Two approaches for the metrological characterization of the imbalance are preferred.

[0087] 20

[0038] Firstly, acceleration sensors can be mounted on the spindle. In addition, the angular position and rotational speed of the rotor can be measured with an optical or electrical sensor. The imbalances can be determined from the synchronously read signals of the acceleration in the radial direction and the angular position. The acceleration signal can be integrated so that a vibration velocity or, after a second integration, the rotor displacement is obtained as a measured value. By using two acceleration sensors, measurements can be taken in two planes. In addition to the pure displacement of the rotor in one plane, a tau-

[0088] The 30-degree movement of the rotor is determined by analyzing the phase positions of the two accelerometers. A measuring system consisting of an accelerometer, a rotation sensor, and evaluation electronics with

[0089] Patent attorneys Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025 Software can be used as a standalone unit that can be attached to the spindle for the purpose of balancing.

[0090]

[0039] Alternatively or additionally to the use of acceleration¬

[0091] With 5 sensors, an integrated position measurement system can be used. Instead of an external rotation sensor, a machine-integrated rotary encoder is used to determine the angular position of the spindle. Instead of an accelerometer, a linear encoder of the linear axis on which the spindle can be mounted can be read. The Ro-

[0092] The rotation axis of the spindle is preferably orthogonal to the direction of travel of the linear axis, so that the radially acting imbalance force of the rotating spindle acts in the direction of the drive motor of the linear axis. A following error detected here can be related to the angular position of the spindle rotor and used to determine the actual imbalance.

[0093]

[0040] According to the invention, the imbalance is not compensated manually by adjusting screws or applying adhesive strips, but rather the rotated spindle is counteracted by rotationally asymmetric machining.

[0094] The balancing ring is balanced by removing material from a balancing ring. It is detachably mounted coaxially to the axis of rotation on the spindle and has an inner diameter larger than the outer diameter of the workpiece holder. The balancing ring is therefore a wear part or consumable of the ultra-precision lathe according to the invention. When the balancing ring is worn, it must be replaced with a new one.

[0095]

[0041] The workpiece holder can be, for example, a vacuum chuck or another system for mechanical, magnetic or adhesive clamping.

[0096] 30 siven clamping of a workpiece.

[0097]

[0042] The balancing method according to the invention can run fully automatically, by automatically determining an imbalance

[0098] Patent attorneys Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025: A turning program is calculated to create recesses in the balancing ring using a dynamic feed movement of a tool. The measurement, the calculation of the correction, and the machining of the balancing ring can all be fully automated.

[0099] The five recesses can have different geometries: fine cups, longer indentations, or larger recesses. By reducing the cup depth and width, fine balancing can be achieved with this approach. It is particularly advantageous to incorporate a circumferential groove or channel into one end face of the balancing ring, whereby the

[0100] 10. The depth of the groove or slot is rotationally asymmetrically distributed, meaning that the depth of the groove or slot is calculated to vary across the angle of rotation in order to compensate for a specific imbalance. The depth of the groove or slot can vary in a wavy pattern along the angle of rotation, with the wave amplitude and / or wave frequency also varying across the angle of rotation. For larger imbalances, two or more such grooves or slots may be advantageous.

[0101]

[0043] By using online measurement technology of the machine to determine residual imbalance, it is possible to detect this during or after between

[0102] The workpiece's balance can be checked and corrected as needed during 20 machining steps for quality control purposes. This is particularly useful for rotationally asymmetrical workpiece geometries, which inherently introduce an imbalance during manufacturing. Therefore, after partial machining of the rotationally asymmetrical workpiece, the imbalance can be measured and corrected to ensure optimal balancing conditions for the final machining cut.

[0103]

[0044] Before clamping and balancing a second component, the

[0104] 30 balancing rings already used for balancing are continuously over-rotated and thus reset. This iterative processing of the lost balance

[0105] Patent attorneys Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025 The balancing ring for individual balancing and subsequent resetting can be performed until a minimum thickness of the balancing ring has been reached. After that, the used balancing ring must be exchanged and replaced.

[0106] 5

[0107]

[0045] If integrated sensors make it possible to measure the balance state in two planes, two axially offset separate balancing ring parts mounted in the chuck and a correspondingly extended mathematical calculation of the balance state can also be used to measure the balance state in two planes.

[0108] 10 levels will be corrected.

[0109]

[0046] The disclosure is explained in more detail below with reference to exemplary embodiments illustrated in the drawings. The drawings show:

[0110] Fig. 1 shows a perspective detail view of an exemplary embodiment of an ultra-precision lathe according to the invention;

[0111] Fig. 2 shows a perspective view of an exemplary embodiment of a balancing ring according to an ultra-precision rotary tool according to the invention.

[0112] 20 machines;

[0113] Fig. 3 shows a perspective view of another exemplary embodiment of a balancing ring according to an ultra-precision lathe according to the invention; and

[0114] Fig. 4 shows a perspective view of the embodiment of the balancing ring according to Fig. 2 with a schematic detail view of material removal structures; and

[0115] Figure 5 shows a schematic flowchart of an embodiment of the balancing method according to the invention.

[0116] Patent Attorneys Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025

[0047] Fig. 1 shows an ultra-precision lathe 1 for ultra-precise forming of a workpiece 3. The workpiece 3 is held in a workpiece holder 5, here in the form of a vacuum chuck, wherein the workpiece holder 5 is located at an end face of a spindle

[0117] 5 7 of the ultra-precision lathe 1. The spindle 7 is rotatably mounted about a rotary axis L. A motor (not shown here) of the ultra-precision lathe 1 is configured to rotate the spindle 7 at a defined speed about the rotary axis L, so that the workpiece 3, which is held by means of the workpiece holder 5, also rotates about

[0118] 10 the axis of rotation L rotates.

[0119]

[0048] The ultra-precision lathe 1 also has a tool 9 for material removal that can be dynamically adjusted relative to the spindle 7. The tool 9 can, for example, be a monocrystalline diamond tool. The spindle 7 is, in the embodiment shown,

[0120] 15. Example: Mounted on a linear axis 1 1 oriented horizontally perpendicular to the axis of rotation L. A linear encoder (not shown here) of the linear axis 1 1 can serve as a sensor for the indirect determination of an imbalance of the spindle 7, since an imbalance force acting radially to the axis of rotation L of the rotating spindle 7 in the direction of a drive motor (not shown here)

[0121] (20 shows) the linear axis 1 1 acts. A following error read by the linear encoder can be related to the current angular position of the spindle 7 and used to determine the actual imbalance. Alternatively to a linear encoder of the linear axis 1 1, for example at least one accelerometer can be used for the direct determination of

[0122] 25 mung of an imbalance on the spindle 7 be arranged.

[0123]

[0049] According to the invention, the ultra-precision lathe 1 has a balancing ring 13 which is detachably attached to the spindle 7 coaxially with the axis of rotation L. The inner diameter of the balancing ring 13 is larger than the outer diameter of the workpiece holder 5, so that the balancing ring 13

[0124] Patent attorneys Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025 the workpiece holder 5 can be detachably attached to the spindle 7 in a circumferential manner. The balancing ring 13 serves as a consumable material that can be removed rotationally asymmetrically by dynamically adjusting the tool 9 while the spindle 7 is rotating, in order to achieve a result by means of the linear encoder

[0125] 5 coders of the linear axis 1 1 to compensate for a certain imbalance by machining material from the balancing ring 13.

[0126]

[0050] The material of the balancing ring 13 can be removed from an end face 15 of the balancing ring 13 and / or from a circumferential surface 17 of the balancing ring 13. Material removal from the end face is preferred.

[0127] 10 15 of the balancing ring 13, since the workpiece 3 is also essentially machined on its end face. The tool 9 for machining material from the balancing ring 13 can be the same tool 9 that is also used for machining the workpiece 3, or a separate tool 9.

[0128] 15

[0051] For better orientation in the figures, a right-handed Cartesian coordinate system is shown in each case, in which the z-axis runs in the direction of the axis of rotation L, the x-axis extends in the direction of the horizontal linear axis 1 1 of the spindle 7 and the y-axis corresponds to a vertical axis upwards. The tool 9 is preferably

[0129] 20 in the y-direction at the same vertical height as the axis of rotation L of the spindle 7. If the material removal from the balancing ring 13 takes place from the cylindrical surface 17 of the balancing ring 13, the tool 9 is positioned in the z-direction so that it is next to the balancing ring 13 in the x-direction and is moved by radial dynamic feeding of the spindle 7 along the

[0130] 25 Linear axis 1 1 is brought into machining engagement with the material of the balancing ring 13. Alternatively or additionally, the tool 9 can be dynamically moved radially onto the cylindrical surface 17 of the balancing ring 13 on a linear axis supported in the x-direction.

[0131] Patent Attorneys Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025

[0052] In the preferred material removal from the end face 15 of the balancing ring 13, the tool 9 is positioned in the z-direction in front of the end face 15 of the balancing ring 13 and is dynamically moved axially, i.e. in the z-direction, in order to engage in machining with the end face 15 of the balancing ring 13.

[0132] 5 Regardless of whether the material removal takes place from the end face 15 and / or from the cylindrical surface 17 of the balancing ring 13, the dynamic positioning of the tool 9 uses the machine-internal information about the angular position of the spindle 7 at any given moment to carry out the material removal in the desired angular range in a rotationally asymmetric manner in order to compensate for an imbalance determined by means of a linear encoder of the linear axis 1 1.

[0133]

[0053] Fig. 2 shows the balancing ring 13 and the workpiece holder 5 for receiving the workpiece 3 in more detail. The cylindrical surface 17 of the balancing ring 13 can have two cylindrical surface sections 17a,b, which are

[0134] 15 are arranged offset from each other in the direction of the axis of rotation L, i.e., in the z-direction. The balancing ring 13 can be designed in two parts, wherein a first lateral surface section 17a of the balancing ring 13 can belong to a first balancing ring part 13a and a second lateral surface section 17b of the balancing ring 13 can belong to a second balancing ring part 13b.

[0135] 20 can be heard. In this case, the balancing ring parts 13a,b are arranged offset from each other in the z-direction. The advantage of the cylindrical surface sections 17a,b, offset in the longitudinal direction of the axis of rotation L, is that balancing can be carried out in different planes offset in the z-direction in order to compensate for second- or higher-order imbalances by selectively performing material removal from either the first cylindrical surface section 17a and / or the second cylindrical surface section 17b, depending on the current angular position. The balancing ring parts 13a,b can preferably have an axial distance from each other in the z-direction to provide a larger lever for compensation.

[0136] 30 of second or higher order imbalances.

[0137] Patent Attorneys Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025

[0054] Fig. 3 shows an embodiment of the balancing ring 13, in which the balancing ring 13 is stepped and has two annular end faces 15a,b, wherein the two annular end faces 15a,b have an axial distance A from each other. The annular end faces 15a,b can

[0138] 5 be formed by a one-piece balancing ring 13, which is stepped in a stair-like manner, or belong to different balancing ring parts 13a,b, wherein the balancing ring part 13b, which is offset rearward by the axial distance A in the z-direction, has a larger outer diameter than the balancing ring 13a, which is arranged further forward in the z-direction. Regardless of whether the balancing ring 13 is designed as a single piece or in multiple parts, the embodiment according to Fig. 3 offers the advantage that by removing material from either the front end face 15a and / or the rear end face 15b by means of dynamic feed of the tool 9 in the z-direction, different areas are created in the z-direction by the axial distance A.

[0139] 15 levels can be used to compensate for second or higher order imbalances.

[0140]

[0055] Figure 4 schematically shows that the dynamic positioning of the tool 9 towards the balancing ring 13 can lead to different material removal structures 19 on the balancing ring 13. The geometry of the material

[0141] The material removal structure 19 can correspond to fine cups, elongated indentations, or larger recesses. By adjusting the cup depth, width, and / or density, very fine balancing can be achieved automatically without the need for manual adjustments of screws or adhesive strips. It is particularly advantageous to incorporate a circumferential groove or channel 21 into the end face 15 of the balancing ring 13 as the material removal structure 19, wherein the depth T of the groove or channel 21 is rotationally asymmetrically distributed, i.e., the depth T of the groove or channel is calculated so that it varies with the angle of rotation. <p variiert, um eine bestimmte Unwucht auszugleichen. Die Tiefe T der Nut bzw. Rille

[0142] 30 21 varies here in a wavy pattern along the rotation angle cp, with the wave amplitude and / or the wave frequency also varying over the rotation angle

[0143] Patent attorneys Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025 <p variiert. Die endgültige Rille bzw. Nut 21 kann in Tausenden von Umdrehungen eingearbeitet werden. Bei größeren Unwuchten können zwei oder mehr solcher Nuten bzw. Rillen 21 sinnvoll sein. Es kann auch zusätzlich jederzeit bei Bedarf zwischen Bearbeitungsschritten am Werkstück 3

[0144] 5. The balance can be readjusted by removing material from the balancing ring 13.

[0145]

[0056] Fig. 5 shows a flowchart of an embodiment of the balancing method according to the invention. In a first step 501, the spindle 7 is rotated with the workpiece 3 clamped in it. The remaining steps of the method preferably take place with the spindle 7 rotating, so that the ultra-precision lathe 1 does not have to be stopped and restarted for balancing. In a second step, an imbalance is determined as described above, for example by means of the linear encoder of the linear axis 1 1 of the ultra-precision lathe 1, on which

[0146] 15 The spindle 7 is mounted to be movable in the x-direction. In the following step 505, it is checked whether a desired balance quality has been achieved, i.e., whether the imbalance just determined is below a predetermined tolerance limit. If this is the case (yes), then the machining of the workpiece 3 follows in step 507. After or during the machining

[0147] 20. Machining of workpiece 3 in step 507, or after partial machining of workpiece 3 in step 507, an imbalance can again be determined in step 503 and the balance quality checked in step 505. Therefore, if the workpiece is not yet finished in step 509 (no), the process can continue from step 503 to readjust the balance.

[0148]

[0057] If the required balance quality is not achieved in step 505 (no), a material removal profile is calculated in step 511. The material removal profile defines the desired shape of the balancing ring 13, which is necessary to compensate for the imbalance determined in the preceding step 503. The material removal profile can, for example, consist of one or more grooves.

[0149] 30 len or grooves 21 define, the depth T of which depends on the angle of rotation <p variiert.

[0150] Patent Attorneys Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025 In the following step 513, the imbalance is then corrected by removing material from the balancing ring 13 according to the calculated material removal profile. Once the material removal profile has been completed, the balance quality is recursively checked again in step 505.

[0151] Step 5 is now reached. If so, proceed to step 507; if not, steps 511 and 513 are repeated. If the workpiece is finished in step 509 (yes), the balancing ring can be smoothed in a final step 515 for subsequently processed workpieces, so that it is rotationally symmetrical again.

[0152]

[0058] The numbered designations of the components or directions of movement as “first”, “second”, “third”, etc. are chosen here purely arbitrarily for the purpose of distinguishing the components or directions of movement from one another and can be chosen differently at will. No rank of importance is associated with them. A designation of a component or technical

[0153] The fact that the 15th niche feature is the "first" should not be misinterpreted to mean that there must be a second component or technical feature of this type. Furthermore, any process steps, unless explicitly stated otherwise or absolutely necessary, can be carried out in any order and / or partially or completely overlapping in time.

[0154]

[0059] Equivalent embodiments of the parameters, components, or functions described herein that appear obvious to a person competent in the field of this description are hereby included as if they were explicitly described. Accordingly, the protection-

[0155] 25. The scope of claims includes such equivalent embodiments. Features described as optional, advantageous, preferred, desirable, or similar, such as "may," are to be understood as optional and not as limiting the scope of protection.

[0156] Patent Attorneys Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025

[0060] The described embodiments are to be understood as illustrative examples and do not constitute an exhaustive list of possible embodiments. Each feature disclosed in relation to an embodiment may be used alone or in combination with one or

[0157] 5. Several other features may be used, regardless of the embodiment in which the features are described. While at least one embodiment is described and shown herein, modifications and alternative embodiments that appear obvious to a person skilled in the art in view of this description are also covered by the scope of protection of this disclosure. Furthermore, the term “have” is not intended to exclude additional other features or process steps, nor is “a” or “an” intended to exclude a plurality.

[0158]

[0061] List of reference symbols:

[0159] 15 I Ultra-precision lathe

[0160] 3 workpieces

[0161] 5 Workpiece holder

[0162] 7 spindles

[0163] 9 tools

[0164] 20 II Linear axis

[0165] 13 Balancing ring

[0166] 13a,b Balancing ring parts

[0167] 15 Front

[0168] 15a,b End face sections

[0169] 17 Surface area

[0170] 17a,b lateral surface sections

[0171] 19 material removal structures

[0172] 21 groove or slot

[0173] 501 Turning the spindle

[0174] 30 503 Determining an imbalance

[0175] 505 Checking the balance quality

[0176] Patent attorneys Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025 507 Machining of the workpiece

[0177] 509 Check if the workpiece is completely machined

[0178] 51 1 Calculating a material removal profile

[0179] 513 Balancing by material removal from the balancing ring

[0180] 5 515 Smoothing the balancing ring

[0181] A axial distance

[0182] L axis of rotation

[0183] T Depth of the groove or slot

[0184] 10

[0185] Patent attorneys Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025

Claims

Claims 1. Ultra-precision lathe (1 ) for ultra-precise shaping of a workpiece (3), wherein the ultra-precision lathe (1 ) comprises: 5 a spindle (7) with a workpiece holder (5) for receiving a workpiece (3) to be machined, wherein the spindle (7) defines a rotational axis (L) about which the spindle (7) with a workpiece (3) received by means of the workpiece holder (5) is rotatable, 10 at least one tool (9) that can be dynamically adjusted relative to the spindle (7) for material removal by machining, and at least one sensor for directly or indirectly determining an imbalance of the spindle (7), characterized in that the ultra-precision lathe (1) further comprises a balancing ring (13) which is detachably attached to the spindle (7) coaxially to the axis of rotation (L), wherein the balancing ring (13) has an inner diameter that is larger than an outer diameter of the workpiece holder (5), wherein material of the balancing ring (13) is dynamically 20. The adjustment of the at least one tool (9) with the spindle (7) rotating is rotationally asymmetrical in order to compensate for an imbalance determined by means of the at least one sensor by machining material from the balancing ring (13).

2. Ultra-precision lathe (1) according to claim 1, wherein the balancing ring (13) has at least one annular end face (15) and the at least one tool (9) is configured to dynamically feed material from the at least one end face (15) of the balancing ring (13) while the spindle (7) is rotating asymmetrically. 30 balancing rings (13) to be removed. Attorneys at Law Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025 3. Ultra-precision lathe (1) according to claim 1 or 2, wherein the balancing ring (13) has at least two annular end faces (15) in a stepped manner, wherein the at least two annular end faces (15) have an axial distance (A) from each other. 5 4. Ultra-precision lathe (1 ) according to one of the preceding claims, wherein the balancing ring (13) is designed in multiple parts, wherein each part (13a,b) of the balancing ring (13) provides a material removal surface (15a,b, 17a,b) preferably on its end face, wherein the material removal surfaces (15a,b, 17a,b) have an axial distance (A) 10 to each other.

5. Ultra-precision lathe ( 1 ) according to claim 4, wherein the parts (13a,b) of the balancing ring (13) are detachably attached to the spindle (7) with an axial distance to each other and coaxial to the axis of rotation (L). 15 6. Ultra-precision lathe (1 ) according to claim 4 or 5, wherein the parts ( 13a, b) of the balancing ring ( 13) have different outer diameters.

7. Ultra-precision lathe (1) according to one of the preceding claims, wherein the at least one tool (9) is used both for 20 material removal from the balancing ring (13) as well as material removal from a workpiece (3) held by means of the workpiece holder (5).

8. Ultra-precision lathe (1) according to one of the preceding claims, further comprising at least one additional dynamically re- 25. Applicable tool (9) to the spindle (7) for machining the workpiece (3). Attorneys at Law Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025 9. Ultra-precision lathe (1) according to one of the preceding claims, wherein the at least one tool (9) is configured to be picked up once or several times during or between machining steps of a workpiece by means of the workpiece holder (5).

5. Material is removed from the balancing ring (13) by dynamically adjusting the workpiece (3) while the spindle (7) is rotating asymmetrically.

10. Method for ultra-precise shaping of a workpiece (3) using an ultra-precision lathe (1) , wherein the method comprises the following steps: Rotating (501) a spindle (7) of the ultra-precision lathe (1) about a rotary axis (L), wherein the spindle (7) has a workpiece holder (5) for receiving a workpiece (13) to be machined, 15 Direct or indirect determination (503) of an imbalance of the rotated spindle (7) by means of at least one sensor, characterized in that the method further comprises: balancing (513) of the rotated spindle (7) by machining material of a balancing ring (13) which is detachably attached to the spindle (7) coaxially to the axis of rotation (L) and has an inner diameter that is larger than an outer diameter of the workpiece holder (5), wherein the material of the balancing ring (13) is dynamically asymmetrically spac¬ by dynamically adjusting at least one tool (9) while the spindle (7) is rotating 25 is removed to compensate for an imbalance determined by means of the at least one sensor by machining material from the balancing ring (13). 1 1. Method according to claim 10, wherein the steps of rotating (501), determining (503) the imbalance and balancing (513) during atentanwälte Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025 26 / 28 or between machining steps (507) of a workpiece (3) held by means of the workpiece holder (5) are carried out and / or repeated.

12. Method according to claim 10 or 11, wherein for a machining operation 5 processing (507) of the workpiece (3) the same tool (9) is used as for balancing (513).

13. Method according to claim 10 or 1 1 , wherein a separate tool (9) is used for machining (507) the workpiece (3) which is not used for balancing (513). 10 14. Method according to one of claims 10 to 13, wherein during balancing (513) the material of the balancing ring (13) is removed by dynamically adjusting the at least one tool (9) with a rotating spindle (7) in a rotationally asymmetric manner from an annular end face (15) of the balancing ring (13).

15. Method according to any one of claims 10 to 14, wherein a wobbling motion of the spindle (7) is detected when determining the imbalance and material is removed from at least two material removal surfaces (15a,b, 17a,b) of the balancing ring (13) during balancing, wherein the at least two material removal surfaces (15a,b, 17a,b) 20 have an axial distance (A) from each other.

16. The method of claim 15, wherein the at least two material removal surfaces are located on different end faces (15) of a stepped balancing ring (13) and / or on two different parts (13a,b) of a multi-part balancing ring (13). Attorneys at Law Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025 27 / 28 17. Method according to any one of claims 10 to 16, further comprising a step of smoothing (515) the balancing ring (13) before or after machining (507) a workpiece (3) received by means of the workpiece holder (5), wherein the balancing ring (13) 5 is smoothed so that the material of the balancing ring ( 13) is removed by the at least one tool (9) with rotating spindle (7) until the balancing ring (13) again has a rotationally symmetrical material distribution. 10 attorneys Hemmer Lindfeld Frese INNP 3716 WO, 21 / 10 / 2025

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