Workpiece clamping unit, workpiece receiving device, and honing machine

Abstract

The invention relates to a workpiece clamping unit (1) for clamping a workpiece (2, 2') to be machined, in particular during the honing of workpiece bores (3), comprising a housing (4) and a workpiece-surrounding, elastically deformable clamping bush (6) for applying against a workpiece surface (2A). The clamping bush (6) is disposed inside the housing (4) and has a central receiving opening (7) for receiving and clamping the workpiece (2, 2'). An annular pressure chamber (8) is formed between an inner side (5B) of the housing (4) and an outer side (6A) of the clamping bush (6), which pressure chamber is or can be filled and, in the event of a fluidic pressurization, can be applied radially against the workpiece (2, 2') received in the central receiving opening (7). In order to adapt to a contour of the workpiece surface (2A) of the workpiece (2, 2') to be machined, the clamping bush (6) has a plurality of longitudinal grooves (9) on the inner side (6B) of the clamping bush, the longitudinal grooves being distributed about a central axis (M).

Description

[0001] P 62159 WO 18 November 2025

[0002] - 1 - FK / Mu

[0003] Workpiece clamping unit, workpiece holding device and honing machine

[0004] SCOPE OF APPLICATION AND STATE OF THE ART

[0005] The invention relates to a workpiece clamping unit for clamping a workpiece to be machined, particularly during the honing of workpiece bores. The workpiece clamping unit comprises a housing and a workpiece-enclosing, elastically deformable clamping sleeve for contact with a workpiece surface of the workpiece to be machined. The clamping sleeve is arranged within the housing and has a central receiving opening for receiving and clamping the workpiece. A circumferential pressure chamber is formed between an inner side of the housing and an outer side of the clamping sleeve. This chamber is filled or fillable such that, when the pressure chamber is pressurized with fluid, the clamping sleeve can be radially pressed against the workpiece held in the central receiving opening.

[0006] The invention also relates to a workpiece holding device with such a workpiece clamping unit and a honing machine with such a workpiece clamping unit or such a workpiece holding device.

[0007] Honing is a machining process with geometrically undefined cutting edges. A honing tool performs a two-component cutting motion within a bore being machined, maintaining constant surface contact between one or more cutting elements of the honing tool and the bore's inner surface. Honing stones are typically used as the cutting elements. The kinematics of an expandable honing tool are characterized by a superposition of a rotary motion, a stroke motion (usually oscillating) in the axial direction of the bore, and a feed motion that changes the effective diameter of the honing tool. This results in a surface structure on the bore's inner surface with intersecting machining marks.Surfaces finished by honing can meet high requirements regarding dimensional and form tolerances, so that, for example, cylinder bores in cylinder crankcases or cylinder liners, inner surfaces of firearm barrels, bearing surfaces for shafts, e.g., in a crankshaft bearing bore, cylindrical inner surfaces in connecting rod eyes, bearing surfaces on connecting rods, gears, or components for other power and working machines, such as compressors, are frequently machined by honing. The workpieces to be machined can be, for example, turned parts, i.e., workpieces that have already been machined by the turning process.

[0008] In honing, the workpiece is clamped into a workpiece clamping unit. The workpieces must be fixed against both rotation and displacement. One of the major challenges in honing is therefore, on the one hand, clamping relatively thin-walled workpieces without damage or with minimal deformation, and on the other hand, clamping workpieces that do not have a suitable or have a complex outer contour for clamping units.

[0009] For certain workpiece types, hydraulic or pneumatic workpiece clamping units in the form of workpiece-encompassing clamping bushings are used in honing machining. These bushings apply fluidic pressure to the outer surface of the workpiece to be machined in a radial manner, thus enabling the transmission of machining forces via static friction and thereby fixing the workpiece in a force-fit manner.

[0010] German patent application DE 10 2009 051 849 A1 discloses a workpiece clamping device for clamping a workpiece during machining, comprising a frame and a workpiece holding element attached to the frame for contact with a workpiece surface. The workpiece holding element includes a cavity enclosed by wall sections, which is filled or fillable with a rheologically adjustable fluid. A viscosity control device is also provided for controlling the viscosity of the rheologically adjustable fluid contained in the cavity.

[0011] German patent application DE 42 39 180 A1 discloses a form-fit clamping jaw for a clamping device comprising a base body and a clamping surface arranged on the base body, which can be adapted to the surface contour of a workpiece. To enable the clamping surface of the form-fit clamping jaw to adapt to the surface contour of the workpiece, the clamping surface is composed of a plurality of pressure pieces that are displaceable relative to the base body and lockable in a clamping position on the base body.

[0012] German patent application DE 19 14 104 A discloses a holder for a workpiece comprising an elongated tubular sleeve with an inner and an outer surface, an annular elastic sleeve that rests against the inner surface of the sleeve, an annular clamping sleeve that is attached to the inner surface of the sleeve and rests against the inner surface of the elastic sleeve, and a device for supplying a flowable pressure medium into the sleeve, whereby the elastic sleeve is pressed inwards against the outer surface of the clamping sleeve in order to press it against a workpiece and to grip it.

[0013] Such clamping bushings are typically manufactured mechanically, for example by injection molding using specially designed molds, and usually consist of an elastic material, such as a suitable rubber compound, to give them high elasticity and a high coefficient of friction. A challenge in the design of clamping bushings with regard to dimensions, elasticity, and pressure resistance lies in the conflicting requirements. On the one hand, the material for the clamping bushing should be as thick-walled as possible to obtain the most robust clamping bushing possible, one that can reliably dissipate even high machining forces.On the other hand, the material for the clamping sleeve should be as thin-walled as possible in order to achieve good adaptability to the workpiece contour of the workpiece to be machined and thus ensure sufficient surface support even with different outer diameters and / or more complex outer contours.

[0014] TASK AND SOLUTION

[0015] The invention addresses the technical problem of providing a workpiece clamping unit of the type mentioned above, which offers further advantages over the prior art mentioned above, particularly with regard to adaptability to the workpiece to be machined, robustness, productivity, automation, and / or workpiece quality. Furthermore, a workpiece holding device with such a workpiece clamping unit and a honing machine with such a workpiece clamping unit or such a workpiece holding device are to be provided.

[0016] The invention solves this problem by providing a workpiece clamping unit with the features of claim 1, a workpiece holding device with the features of claim 8, and a honing machine with the features of claim 10. Advantageous embodiments of the invention are specified in the dependent claims, the wording of which is hereby incorporated by reference into the description. This includes, in particular, all embodiments of the invention resulting from the combinations of features defined by the cross-references in the dependent claims.

[0017] In the workpiece clamping unit according to the invention, the clamping sleeve has several longitudinal grooves on its inner surface, distributed around a central axis, to adapt to the contour of the workpiece surface of the workpiece to be machined. The clamping sleeve has a hollow cylindrical shape and is designed to completely enclose the workpiece to be machined. Depending on the design of the workpiece clamping unit or the clamping sleeve, and also the diameter of the workpiece to be clamped, the number of longitudinal grooves can vary. The number of longitudinal grooves can, for example, range from four to 30. The longitudinal grooves are preferably arranged evenly distributed around the central axis of the clamping sleeve. The longitudinal grooves are preferably parallel to the central axis of the clamping sleeve. The longitudinal grooves are preferably formed in the form of rectangular grooves. This allows for a relatively uniform material thickness of the wall of the clamping sleeve.Alternatively, the longitudinal grooves can also have a round or semicircular cross-section.

[0018] One advantage of this solution is that the longitudinal grooves on the inside of the clamping sleeve, due to the resulting geometric weakening of the wall, improve its adaptability to the outer contour of the workpiece being machined. This enables reliable clamping of workpieces with varying degrees of complexity. Furthermore, any fluid, such as oil, that enters or has entered the clamping sleeve between the inside and outside of the workpiece can drain away via these longitudinal grooves, preventing the formation of a lubricating film between the clamping sleeve and the workpiece and ensuring that static friction is maintained permanently.

[0019] In a further development of the invention, the clamping sleeve additionally features several longitudinal grooves on its outer surface, distributed around its central axis. This represents a structurally and functionally advantageous implementation of the clamping sleeve, as the longitudinal grooves on both the inner and outer surfaces of the clamping sleeve provide even better adaptability to the outer contour of the workpiece being machined. The longitudinal grooves are preferably arranged evenly distributed around the central axis of the clamping sleeve. The longitudinal grooves are preferably parallel to the central axis of the clamping sleeve. Depending on the design of the workpiece clamping unit or the clamping sleeve, and also the diameter of the workpiece to be clamped, the number of longitudinal grooves on the outer surface can vary. The number of longitudinal grooves can, for example, range from four to 30.The number of longitudinal grooves on the outside of the clamping sleeve preferably corresponds to the number of longitudinal grooves on the inside of the clamping sleeve. The longitudinal grooves on the inside and outside of the clamping sleeve preferably form a meandering wall shape. The actual wall of the clamping sleeve thus has a meandering cross-section. The longitudinal grooves on the inside and outside are therefore arranged alternately next to each other in the circumferential direction. The meandering wall shape also contributes to requiring relatively low fluidic pressure for workpiece clamping, since the meandering design geometrically weakens the clamping sleeve at suitable points, thus providing the lowest possible modulus of elasticity while still maintaining high strength. This is because, due to this design, the wall of the clamping sleeve has an actual material thickness that is significantly less than the effective thickness.

[0020] The longitudinal grooves on the inside and / or outside of the clamping sleeve preferably extend over substantially the entire length of the clamping sleeve. In alternative embodiments, the longitudinal grooves do not extend over the entire length and may, for example, be present only in certain sections, depending on the outer contour of the workpiece to be machined. This also applies to the distribution of the longitudinal grooves around the central axis of the clamping sleeve. It is possible that the longitudinal grooves of the clamping sleeve are arranged irregularly around the central axis of the clamping sleeve and, depending on the outer contour of the workpiece to be machined, are concentrated in a specific circumferential section of the clamping sleeve.

[0021] In a further development of the invention, the clamping sleeve is divided axially into several sections of different diameters. This represents a structurally and functionally advantageous implementation of the clamping sleeve, which further improves its adaptability to the outer contour of a workpiece being machined. The number of sections of different diameters can, for example, range from two to ten. The clamping sleeve is preferably adapted to a contour of the workpiece surface. Furthermore, despite the stepped design, the clamping sleeve is preferably formed in one piece, so that only one pressure chamber is required.

[0022] In a further development of the invention, the clamping bushing has a collar at at least one end. This increases the clamping bushing's rigidity. Furthermore, it allows for improved fastening of the clamping bushing in the housing and also improves the sealing of the pressure chamber. The collar is flange-shaped and projects radially outwards from the bushing body of the clamping bushing. The collar is preferably formed integrally with the clamping bushing. In advantageous embodiments, the clamping bushing has such a collar at each end.

[0023] In a further development of the invention, the clamping bushing is made of a polyurethane-based material. This material exhibits advantageous properties with regard to its adaptability, elasticity, and coefficient of friction with respect to the workpiece being machined. Other plastics with elastomeric properties are also conceivable.

[0024] In a further development of the invention, the clamping bushing is manufactured using a 3D printing process. This represents a structurally and functionally advantageous implementation for the production of clamping bushings. Conventional manufacturing of such clamping bushings can be relatively complicated, especially when the workpieces to be clamped do not have a circular cylindrical outer contour, but rather a more complex one. Using the 3D printing process, even more complex clamping bushing designs for workpieces with more complex outer contours can be produced economically. Furthermore, this also allows the number, arrangement, orientation, distribution, and / or length of the longitudinal grooves on both the inside and outside of the clamping bushing to be quickly and easily adapted to the workpiece being machined.

[0025] In a further development of the invention, an axial stop element associated with the clamping sleeve is provided to determine the axial position of the clamping sleeve in the housing. Besides axially fixing the clamping sleeve, this also improves the sealing of the pressure chamber, particularly at very high fluid pressures. The axial stop element has a stop surface, which is preferably perpendicular to the longitudinal axis of the clamping sleeve. The clamping sleeve rests against this stop surface with its end face. The axial stop element is preferably detachably connected to the housing.

[0026] In a further development of the invention, the workpiece clamping unit comprises a device for introducing or removing a fluid pressure medium into the pressure chamber for fluidic pressurization, whereby the clamping sleeve can be pressed against the outer surface of the workpiece to be machined in the direction of the central axis in order to grip it.

[0027] The workpiece holding device according to the invention comprises a workpiece clamping unit according to the invention and a receiving device for receiving the workpiece clamping unit. The receiving device is preferably a gimbal device, a floating device, or a clamping device. The workpiece clamping unit is pivotable about two mutually perpendicular gimbal axes by means of the gimbal device and is preferably displaceable along the gimbal axes. For this purpose, the gimbal device has a first gimbal holder, which is pivotable about a first gimbal axis relative to a bearing arrangement of the workpiece holding device, and carries a second gimbal holder, which is pivotable about a second gimbal axis relative to the first gimbal axis. The honing machine according to the invention is configured for machining an inner surface of a bore in a workpiece by means of at least one honing operation.The honing machine comprises a honing unit, which includes a spindle unit with a spindle shaft and a spindle axis. A honing tool can be directly or indirectly coupled to the spindle shaft. The honing tool has at least one cutting element that can be pressed against the inner surface of the bore for material removal. The spindle shaft can be moved back and forth parallel to the spindle axis by means of a reciprocating drive to generate a stroke motion, and can be rotated about the spindle axis by means of a rotary drive to generate a rotary motion superimposed on the stroke motion. The reciprocating drive and the rotary drive are connected to a control unit of the honing machine and can be controlled by control signals from the control unit.

[0028] The honing machine is associated with a workpiece clamping unit or a workpiece holding device according to the invention.

[0029] BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Further advantages and aspects of the invention will become apparent from the claims and from the description of exemplary embodiments of the invention, which are explained below with reference to the figures. These figures show:

[0031] Fig. 1 shows a schematic longitudinal section of a workpiece clamping unit according to the invention, in which a rotationally symmetrical workpiece is clamped,

[0032] Fig. 2 shows a schematic longitudinal section of the workpiece clamping unit of Fig. 1, wherein the view is rotated by 90° about a central axis of the workpiece clamping unit compared to Fig. 1.

[0033] Fig. 3 shows an oblique perspective top view of a first embodiment of a clamping bushing of the workpiece clamping unit,

[0034] Fig. 4 shows a longitudinal section of the clamping sleeve from Fig. 3,

[0035] Fig. 5 shows an oblique perspective top view of a second embodiment of a clamping bushing,

[0036] Fig. 6 shows a longitudinal section of the clamping sleeve from Fig. 5, Fig. 7 a sectional view along a line VII-VII from Fig. 6,

[0037] Fig. 8 shows an oblique side view of a third embodiment of a clamping bushing with several sections of different diameters,

[0038] Fig. 9 shows a schematic longitudinal section of a workpiece holding device according to the invention with a workpiece clamping unit according to the invention, in which a workpiece with a complex outer contour is clamped, and

[0039] Fig. 10 shows a schematic side view of a honing machine according to an embodiment with a workpiece clamping unit according to the invention.

[0040] DETAILED DESCRIPTION OF THE EXECUTION EXAMPLES

[0041] Fig. 10 shows a schematic side view of a honing machine 100 according to an exemplary embodiment of the invention. The honing machine 100 is designed and configured to machine an inner surface of a bore 3 in a workpiece 2, 2' by means of at least one honing operation.

[0042] The honing machine 100 has a honing unit 110. The honing unit 110 comprises a spindle unit 111 with a spindle shaft and a spindle axis SA. A honing tool 120 can be directly or indirectly coupled to the spindle shaft of the spindle unit 111.

[0043] The honing tool 120 has at least one cutting material body 121 that can be pressed against the inner surface of the bore 3 for material removal machining of the inner surface.

[0044] The spindle shaft can be moved back and forth parallel to the spindle axis SA by means of a lifting drive to generate a lifting motion. The spindle shaft can also be rotated about the spindle axis SA by means of a rotary drive to generate a rotary motion superimposed on the lifting motion.

[0045] In the illustrated embodiment, the lifting drive and the rotary drive are connected via signal transmission to a control unit of the honing machine 100 (not shown in the figures) and can be controlled by control signals from the control unit. In the illustrated example, the control unit is already integrated into the honing machine 100. A workpiece holding device 30 according to the invention is associated with the honing machine 100 (Fig. 10).

[0046] The workpiece holding device 30 comprises a workpiece clamping unit 1 according to the invention and a receiving device for receiving the workpiece clamping unit 1. In the embodiment shown, the receiving device is designed in the form of a cardan joint device 50.

[0047] In the example shown in Figures 9 and 10, the workpiece clamping unit 1 is pivotable about two mutually perpendicular cardan axes K1 and K2 by means of the cardan joint 50 and axially displaceable within limits along the cardan axes K1 and K2 to achieve a floating motion. For this purpose, the cardan joint 50 has a first cardan holder 51, which is pivotable about a first cardan axis K1 relative to a bearing assembly 53 of the workpiece holding device 30, and carries a second cardan holder 52, which is pivotable about a second cardan axis K2 relative to the first cardan axis K2, as shown particularly in Figure 9.

[0048] The bearings have a small amount of axial play, so that the workpiece clamping unit 1 can perform a floating movement in addition to the angular compensation movement.

[0049] In embodiments not shown in the figures, the receiving device is a floating device or a clamping device, the workpiece clamping unit 1 and thus the workpiece 2, 2' are fixed immovably.

[0050] The workpiece clamping unit 1 is designed to clamp a workpiece 2, 2' to be machined during the honing of workpiece bores 3. In the example according to Figures 1 and 2, the workpiece 2 to be machined has a cylindrical outer shape. The workpiece 2' to be machined according to Figures 9 and 10, on the other hand, has a very complex outer contour.

[0051] The workpiece clamping unit 1 is cylindrical overall and has a housing 4 in which a recess 5 is provided in the form of an axially through-hole, which is radially widened outwards in sections. An elastically deformable clamping sleeve 6, 6', 6" is inserted into this through-hole for contact with a workpiece surface 2A of the workpiece 2, 2' to be machined, such that a circumferential pressure chamber 8 is formed between an inner surface 5B of the housing 4 and an outer surface 6A of the clamping sleeve 6, 6', 6". This pressure chamber 8 can be filled with a fluid. For this purpose, in the example shown (Fig. 2), the housing 4 has two radial fluid channels 15 leading into and out of the pressure chamber 8, which function as fluid inlet and / or fluid outlet.

[0052] The workpiece clamping unit 1 in the examples shown is hydraulic. The fluid used can be incompressible, which allows high forces to be transmitted or applied in the pressure chamber 8.

[0053] The clamping sleeve 6, 6', 6" is a sleeve body that is sleeve-shaped and rotationally symmetrical and has a wall 14 which encloses a central receiving opening 7 for receiving and clamping the workpiece 2, 2'. Due to the elastic deformability of the clamping sleeve 6, 6', 6" it can be radially pressed against the workpiece 2, 2' held in the central receiving opening 7 when fluidic pressure is applied. The clamping sleeve 6, 6', 6" thus adapts to the outer contour of the workpiece 2, 2' to be machined, as shown particularly in Fig. 9.

[0054] The clamping bushing 6, 6', 6" has a collar ring 12 at each end. The collar ring 12 has an increased outer diameter compared to the rest of the bushing body of the clamping bushing 6, 6', 6"; that is, the collar ring 12 is flange-shaped and projects radially outwards from the bushing body of the clamping bushing 6, 6', 6" as shown particularly in Figures 4 and 6.

[0055] The workpiece clamping unit 1 comprises an upper axial stop element 13, which is designed to define the axial position of the clamping bushing 6' in the housing 4. The upper axial stop element 13 is detachably connected to the housing 4 at its upper surface. The upper of the two collar rings 12 is firmly clamped between the upper surface of the housing 4 and a lower surface, or stop surface 18, of the upper axial stop element 13. The lower of the two collar rings 12 is firmly clamped between a lower surface of the housing 4 and a upper surface, or stop surface 19, of a lower axial stop element 16 (Figs. 1 and 2). The lower axial stop element 16 is screwed to a workpiece holder 17.

[0056] The clamping sleeve 6 of the first embodiment (Figs. 1 to 4) has several longitudinal grooves 9 on its inner surface 6B, in this example eight, distributed around a central axis M to adapt to the contour of the workpiece surface 2A of the workpiece 2 to be machined (Figs. 3 and 4). The longitudinal grooves 9 are formed in the wall 14. The longitudinal grooves 9 extend between the two flanged rings 12 over substantially the entire length of the clamping sleeve 6. The ends project into an end region of the flanged rings 12 and do not extend through, so that the flanged rings 12 retain high rigidity. The outer surface 6A of the clamping sleeve 6 according to the first embodiment is smooth.

[0057] The clamping sleeve 6' of the second embodiment (Figs. 5 to 7) has, in order to adapt to a contour of the workpiece surface 2A of the workpiece 2 to be machined, not only several longitudinal grooves 9 on its inner side 6B, in this example 13, distributed around the central axis M, but also several longitudinal grooves 10 on its outer side 6A, in this example 13, distributed around the central axis M, as shown in Fig. 5. In this example as well, the longitudinal grooves 9, 10 extend between the two flanged rings 12 over essentially the entire length of the clamping sleeve 6'. However, the ends of the longitudinal grooves 9, 10 do not project into the end region of the flanged rings 12, but are spaced apart from them (Fig. 6).

[0058] The clamping sleeve 6" of the third embodiment (Figs. 8 to 10) also has several longitudinal grooves 9, 10, arranged around the central axis M in this example, both on its inner side 6B and on its outer side 6A, to adapt to the contour of the workpiece surface 2A of the workpiece 2 to be machined, as shown in Fig. 8. The longitudinal grooves 9, 10 also extend between the two flanged rings 12 over essentially the entire length of the clamping sleeve 6".

[0059] In the second and third embodiments of the clamping sleeve 6', 6" the longitudinal grooves 9, 10 on the inner side 6B and on the outer side 6A are arranged alternately in the circumferential direction such that they form a meandering wall shape 11, as shown particularly in Fig. 7. This wall design results in a relatively thick effective thickness d1 of the wall 14, while the actual material thickness d2 of the wall 14 is relatively thin. Furthermore, this allows the clamping sleeve 6', 6" to expand accordion-like despite its high strength.

[0060] The longitudinal grooves 9, 10 are formed in the form of rectangular grooves in the examples shown, as is shown in particular in Fig. 7. This allows for a relatively uniform material thickness d2 of the wall 14.

[0061] In the area of ​​the collar rings 12, the receiving opening 7 of the clamping sleeve 6, 6', 6" widens radially outwards, as shown particularly in Figs. 4 and 6. This facilitates the insertion of the workpiece 2, 2' into the clamping sleeve 6, 6', 6".

[0062] The embodiments of the clamping bushings 6, 6' according to Figs. 3 and 5 each have a hollow cylindrical shape with a uniform diameter D along the axial length. In contrast, the third embodiment of the clamping bushing 6" (Fig. 8) is divided in the axial direction into several, in this example four, sections A of different diameters D. The clamping bushing 6" is adapted to a contour of the workpiece surface 2A of the workpiece 2' to be machined, as shown in particular in Fig. 9.

[0063] As the illustrated and the further embodiments mentioned above clearly demonstrate, the invention provides a workpiece clamping unit for clamping a workpiece to be machined, a workpiece holding device with such a workpiece clamping unit and a honing machine with such a workpiece clamping unit or such a workpiece holding device, which offer advantages over the prior art, in particular adaptability to the workpiece to be machined, productivity, automation and / or workpiece quality.

Claims

Patent claims 1. Workpiece clamping unit (1) for clamping a workpiece (2, 2') to be machined, in particular when honing workpiece bores (3), comprising: - a housing (4) and - a workpiece-encompassing, elastically deformable clamping bushing (6, 6', 6") for contact with a workpiece surface (2A), - wherein the clamping bushing (6, 6', 6") is arranged inside the housing (4) and has a central receiving opening (7) for receiving and clamping the workpiece (2, 2'), - wherein a circumferential pressure chamber (8) is formed between an inner side (5B) of the housing (4) and an outer side (6A) of the clamping sleeve (6, 6', 6"), which is filled or fillable, such that when the pressure chamber (8) is pressurized with fluidic pressure, the clamping sleeve (6, 6', 6") can be radially pressed against the workpiece (2, 2') received in the central receiving opening (7), characterized in that - the clamping sleeve (6, 6', 6") has several longitudinal grooves (9) arranged around a central axis (M) on its inside (6B) to adapt to a contour of the workpiece surface (2A) of the workpiece to be machined (2, 2').

2. Workpiece clamping unit (1) according to claim 1 , further characterized in that the clamping bushing (6', 6") has several longitudinal grooves (10) arranged around the central axis (M) on the outside (6A), wherein preferably the longitudinal grooves (9, 10) on the inside (6B) and on the outside (6A) form a meandering wall shape (11).

3. Workpiece clamping unit (1) according to claim 1 or 2, further characterized in that the clamping sleeve (6") is divided in the axial direction into several sections (A) of different diameters (D) and is in particular adapted to a contour of the workpiece surface (2A) of the workpiece (2, 2') to be machined.

4. Workpiece clamping unit (1) according to one of claims 1 to 3, further characterized in that the clamping bushing (6, 6', 6") has a collar ring (12) at least at one end.

5. Workpiece clamping unit (1) according to one of claims 1 to 4, further characterized in that the clamping bushing (6, 6', 6") is made of a polyurethane-based material.

6. Workpiece clamping unit (1) according to one of claims 1 to 5, further characterized in that the clamping bushing (6, 6', 6") is manufactured by a 3D printing process.

7. Workpiece clamping unit (1) according to one of claims 1 to 6, further characterized in that an axial stop element (13) associated with the clamping bushing (6, 6', 6") is provided for determining the axial position of the clamping bushing (6, 6', 6") in the housing (4).

8. Workpiece holding device (30) with a workpiece clamping unit (1) according to one of claims 1 to 7 and a receiving device for receiving the workpiece clamping unit (1), wherein in particular the receiving device is a cardan joint device (50), a floating device or a clamping device.

9. Workpiece holding device (30) according to claim 8, further characterized in that the holding device is a cardan joint (50), wherein the workpiece clamping unit (1) is pivotable about two mutually perpendicular cardan axes (K1, K2) by means of the cardan joint (50) and is preferably displaceable along the cardan axes (K1, K2), wherein the cardan joint (50) has a first cardan holder (51) which is pivotable about a first cardan axis (K1) relative to a bearing device (53) of the workpiece holding device (30) and carries a second cardan holder (52) which is pivotable about a second cardan axis (K2) relative to the first cardan holder (51) oriented perpendicular to the first cardan axis (K1).

0. Honing machine (100) for machining an inner surface of a bore (3) in a workpiece (2, 2') by means of at least one honing operation with: - a honing unit (110) comprising a spindle unit (111) with a spindle shaft and a spindle axis (SA), - wherein a honing tool (120) can be directly or indirectly coupled to the spindle shaft, which has at least one cutting material body (121) that can be pressed against the inner surface of the bore (3) for material removal machining of the inner surface, - wherein the spindle shaft can be moved back and forth parallel to the spindle axis (SA) by means of a lifting drive to generate a lifting motion and the spindle shaft can be rotated about the spindle axis (SA) by means of a rotary drive to generate a rotary motion superimposed on the lifting motion, - wherein the lifting drive and the rotary drive are connected to a control unit of the honing machine (100) via signal transmission and are controllable by control signals from the control unit, characterized in that - the honing machine (100) is associated with a workpiece clamping unit (1) according to one of claims 1 to 7 or a workpiece holding device (30) according to claim 8.

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