EP2279829B1 - Method for honing bores and honing tool therefor - Google Patents

Description

The invention relates to a method for honing the inner surface of a bore in a workpiece, in particular for honing a cylinder surface in the manufacture of engine blocks for internal combustion engines. Furthermore, the invention relates to a honing tool which is particularly suitable and configured for carrying out the method.

In the production of cylinder blocks of internal combustion engines, the cylinder surfaces are usually finished by a honing process. When using the finishing process Honing considerable efforts are often made to achieve the required component shape with the lowest possible form error.

Even if there are no shape defects immediately after the machining, often the assembly-optimized component geometry is lost by elastic deformation after assembly or during operation of the machined workpiece. For example, it is known that the assembly of the cylinder head on a cylinder block (engine block) can lead to a non-negligible deformation of the cylinder bores, especially in the area of the cylinder head bolts. During engine operation, however, the piston rings, the cylinder bore warped by the mechanical deformation but also by thermal deformation, should be filled in such a way that a clean seal of the combustion chamber is ensured during engine operation. A complete investment of the piston rings on the cylinder bore with the most even and small clearance between the piston ring and the inner cylinder wall is facilitated if the mounted and warm engine has cylinder bores with low cylinder shape error. If the cylinder shape error is too large, the piston rings will not seal properly, engine particulate emissions will increase, efficiency will decrease, and system life may be shortened.

To avoid such problems is in the DE 28 10 322 C2 has been proposed to avoid the deterioration of the cylinder shape of the cylinder bores in the assembly of the cylinder head in that the honing machine block is deformed by means of a chip device which simulates the later deformation by the cylinder head. In the tensioned state, which corresponds to the state present later in the assembly, the honing takes place, then the tension is released again. A similar proposal is in the JP 11-267960 described.

In addition, in order to simulate the deformation by the action of temperature, it is also known to heat the workpiece by means of hot honing oil. However, these methods are complex and expensive and associated with high safety risks for the machine operator. They are therefore used only for one-off production, but not in series production.

The European patent application EP 1 321 229 A1 describes a method for producing a bore, which has an initial shape in the unloaded state and in the operating state a deviating from the initial shape desired shape. The method includes determining the deformation of a hole with a desired shape in the operating state. By means of the desired shape and the determined deformation, the initial shape is determined and the bore is brought by a machining process in the initial shape. The initial shape produced by the method should assume the desired nominal shape in the operating state. In the described embodiment, the desired shape is cylindrical, while the starting shape has a substantially circular cylindrical portion, a substantially elliptical portion and an intermediate transition portion.

In the dissertation " Variable Form Honing by Computer-aided Honing Process Control "by R. Zurrin, published in: wbk - Research Reports from the Institute for Machine Tools and Industrial Engineering of the University of Karlsruhe, Volume 26 (1990 ) it is proposed to solve the problems described by the manufacturing process "Formhonen". This is understood in this document to mean honing with controlled feed movement, which makes it possible to achieve different removal rates during the honing process locally (stroke and angle position-dependent) in order to produce a negative form of the deformations with a defined surface (compare in particular pages 10 to 20). Form honing is explained using the example of deformed cylinder blocks, in which the cylinder bores have a quadruple-symmetrical fourth-round runout, ie a bore shape with 4-fold radial symmetry with respect to the bore axis, have. This non-circular bore shape is achieved by controlling the feed force or the contact pressure of a simply expanding honing tool on the stroke and the rotation angle.

The Japanese patent application JP 2000-291487 A describes methods and honing tools with which a form honing can be performed. In one embodiment, a honing tool has two or three honing stones on its circumference. On the opposite side of the honing stone of the tool body rollers are mounted, which roll during machining on the inner surface of the machined cylinder bore and serve to support the resulting during processing reaction forces against the inner surface of the bore. A delivery system ensures the radial delivery of the honing stone and changes the infeed pressure during the rotation. The delivery system has an electrically controllable piezoelectric element which is arranged between the body of the honing tool and the carrier for the honing stone. As a result, a quick change of the delivery pressure during the rotation of the honing tool is possible. In another embodiment, two axially offset piezoelectric elements are provided for the delivery of a honing stone, so that the holder of the controlled honing stone is pivotable about an axis perpendicular to the tool axis of rotation axis. This makes it possible to produce conical bore shapes.

It is an object of the invention to provide a method of honing the inner surface of a bore with a workpiece that allows non-circular cylindrical bore shapes to be formed with complex deviations from exact circular cylindricity by honing. It is another object of the invention to provide such a method that allows a high flexibility with respect to the non-round bore shape to be achieved in the forming honing. It is another object of the invention to provide a suitable for performing the method honing tool.

To solve these and other objects, the invention provides a method having the features of claim 1 and a honing tool having the features of claim 8.

Advantageous developments of the invention are specified in the appended claims. The wording of all claims is incorporated herein by reference.

In an inventive method for honing the inner surface of a bore in a workpiece, in particular for honing a cylinder surface in the manufacture of cylinder blocks for internal combustion engines, a honing tool is axially movable within the bore and driven to rotate about its tool axis and attached to the honing tool cutting group with at least a cutting material body for material-removing machining of the inner surface is pressed with a feed force to the inner surface. According to the invention, a substantially rigid guidance of the axial movement takes place the honing tool for generating an axial movement of the honing tool substantially parallel to the bore axis of the bore and a temporally asymmetric control of the feed force of a cutting group attached to the honing tool on one side of the tool axis in dependence on the angular position and optionally the stroke position of the honing tool such that the Hole receives a non-circular cylindrical bore shape at least in an axial bore section.

Ideally, during honing of cylinder bores in cylinder blocks, a shape of the cylinder bore should be created which, in the mounted and operating condition of the engine, results in a minimal error in cylinder shape (cylindricity error). To achieve this manufacturing goal of "optimum hole geometry", the negative shape of the defect created by the deformations generated during assembly and during operation should be generated by honing and thus maintained. However, stiffness and thermal deformation are present in structurally nonuniform workpieces e.g. by wall thickness differences and by different connections of the cylinder liners to the engine-internal cooling system o. The like. Not symmetrical. Therefore, for the ideal imaging of the negative mold a honing process is required, which allows the creation of any, usually asymmetrical bore shape.

However, conventional honing methods are limited in this regard. The basic principle of conventional honing lies in the planar contact of the cutting material body and a double cardanic, movable mounting of the honing tool. When delivering completely or nearly symmetrically distributed around the circumference honing an automatic alignment of the tool takes place in the cylinder bore. In the production of non-circular bore shapes, however, there is the problem with this approach that in the Increasing the feed force or the contact pressure at a cutting group on the diametrically opposite to the tool axis side of the tool axis of the contact pressure from there in engagement with the bore wall standing cutting material bodies also automatically increases. Each change of the feed force thus acts on the diametrically opposite side of the tool axis (pressure and counter-pressure side) in the same or very similar manner, so that the shape of the machined bore on diametrically opposite sides changes in substantially the same way. In the approaches described in the prior art, this leads to the formation of a not-circular, but in any case with respect to the bore axis 2-fold radially symmetrical bore shape. This may in particular be an elliptical bore shape or the hole shape with 4-fold radial symmetry described in the dissertation by Zurrin, which represents a special form of the 2-fold radial symmetry.

The invention overcomes this limitation. The substantially rigid guidance of the axial movement of the honing tool in conjunction with the control of the feed force of the cutting group ensures that this cutting group effects a removal of material in its pressure angle range, without necessarily leading to a comparable material removal on the diametrically opposite side of the bore inner surface. The opposing force counteracting the contact pressure of the cutting group is not applied by material-removing cutting body, but by the substantially rigid guidance of the axial movement of the honing tool, which prevents dipping of the honing tool transverse to the tool axis in one-sided pressing of the cutting material body to the bore inner surface.

For flexible control of the bore shape, in particular, a method or a system is proposed in which the contact pressure of cutting material bodies at a limited circumferential angle range the inner surface of the bore can be increased without this also leads to an increase in the contact pressure of other Schneidstoffköper on the diametrically opposite side.

It is possible that the honing tool has only a single cutting group whose cutting material body (one or more) are all arranged on one side of the honing tool. It is also possible to provide a plurality of cutting groups which can be controlled independently of one another and, if appropriate, can also be arranged on diametrically opposite sides of the honing tool. If cutting groups are arranged on opposite sides, at any given time, only on one of the opposite sides should a cutting group be in material-removing engagement with the bore inner wall while the cutting group located on the opposite side is relieved of pressure and thus does not or no substantial material removal ,

Thus, either a honing tool is used, which has a single cutting group with one or more cutting material bodies, which are all arranged on one side of the honing tool, or a honing tool is used which has a plurality of independently deliverable cutting groups, which is ensured by the controller in that the contact pressure of one cutting group is independent of the contact pressure of other cutting groups arranged in other circumferential positions.

The cutting group of the honing tool used is delivered in the claimed invention by means of a base delivery system in a predetermined radial position and starting from the predetermined by the base delivery system radial position is carried out a radial retraction or a radial retraction of the cutting group by means of a independent of the basic delivery system operable dynamic fine delivery system.

The feed movement of the cutting material body of the cutting group is thus controlled by means of a cutting group delivery system, which is divided into two independently operable subsystems. The basic delivery system can be designed so that, in a coarse feed, the material-removing regions of the cutting material body can be approximated with the aid of the base delivery system of the inner surface of the bore at a relatively large first adjustment to a small distance or to the touch. In contrast, the dynamic fine delivery system can be designed for generating short-term change of the delivery pressure and short second adjustment travel relative to the first adjustment path.

Since the fine delivery system can be designed so that only relatively low moving masses are required, the fine delivery system can be designed highly dynamic. In some embodiments, during a single revolution of the honing tool, the fine delivery system generates multiple, in particular now two and ten, periodic or aperiodic changes between increase and decrease in delivery force. As a result, contours of the bore inner wall that are complexly curved and provided with a large number of local maxima and minima can be generated with high accuracy.

During rough delivery, the cutting group can be delivered by means of the base delivery system, for example via a first adjustment, which is at least 1 mm, preferably at least 4 mm. By contrast, the cutting group can be adjusted by means of the fine delivery system via a second adjustment path, which lies in the range below 100 μm, in particular in the range of 20 μm and 60 μm in radius.

In some embodiments, the base delivery system is actuated via a drive located outside of the honing tool and the fine delivery system via a drive disposed within the honing tool. The drive of the base delivery system may be located, for example, in the honing machine. The drive arranged within the honing tool can be, for example, an electromechanical drive or a piezoelectric drive.

These and other embodiments will be explained in connection with the drawing figures.

In a further development of the method, the honing tool is supported for substantially rigid guidance of the axial movement within the bore in an axially slidable manner and substantially immovably transversely to the tool axis. This makes it possible to dispense with outside of the workpiece to be arranged guide devices.

In a further development, a honing tool is used for this purpose, which comprises a set of distributed around the circumference of the honing tool guide rails for axial guidance of the honing tool in the bore, which are preferably fed independently of the cutting group in the direction of the inner surface of the bore, wherein the substantially rigid guidance of the axial movement is achieved in that the guide rails are pressed during the movement of the honing tool in the bore to the inner surface of the bore.

In this process variant, the guide rails center the honing tool within the bore. The guide rails are preferably designed so that they generate little or no material removal, which is referred to herein as "substantially non-cutting guide rails". The guide rails can at least in the coming into contact with the inner surface of the bore areas of a plastic, rubber, an elastomer of suitable hardness (eg Vulkollan®), a metal, a hard metal or a ceramic or it may be honing stones with a high cutting material content.

It is also possible for the substantially rigid guidance of the axial movement of the honing tool to be attained in that the honing tool is guided axially immovably outside the bore of the workpiece and substantially immovably transversely to the tool axis. Depending on the type of bore can this purpose a one-sided guide exclusively on the inlet side of the bore, a one-sided guide only on the inlet side opposite exit side of the bore (in through holes), or provided a two-sided guide both on the inlet side, as well as on the opposite outlet side be. A rigidly against transverse load coupling of the honing tool to a rigidly guided against transverse load honing spindle may possibly also be sufficient to ensure the rigid guidance of the axial movement of the honing tool. Then possibly can be completely dispensed with guide elements in the field of honing tool. The exclusively external guidance of the axial movement of the honing tool requires the highest accuracy in the relative positioning between the workpiece and the honing tool.

In order to obtain the most flexible possible control of the shape of the bore cross section in the machining area, it is provided in a variant that a honing tool is used which has a single separately deliverable cutting group, which preferably has a pressure angle of less than 90 °. The term "pressure angle" here describes the angular range along the circumference of the honing tool, are in the cutting material body of the cutting group in engagement with the bore wall. It is often beneficial when the pressure angle between about 1 ° and about 70 °, it may for example be between 5 ° and 60 ° and / or between 20 ° and 45 °. The smaller the pressure angle, the more accurate is a complex shape of the contour of the inner surface to be achieved by controlling the feed force in dependence on the angular position of the honing tool.

As mentioned honing tools can be used with several independently deliverable cutting groups, if it is ensured by the control that the contact pressure of a cutting group is independent of the contact pressure of other arranged at other circumferential positions cutting groups. If, for example, a honing tool is used with four cutting groups each offset by 90 °, their feed pressure can be controlled in such a way that in each case 90 ° out of phase delivery pressure curves are produced between cutting groups circumferentially offset by 90 °. It can thereby be achieved that during a single revolution of the honing tool, the same peripheral portion of the bore inner wall is reworked by the four cutting groups in succession material removal. As a result, the removal rate can be increased overall.

With the aid of the method, in addition to the non-circular bore shapes which can also be produced by conventional methods, hitherto not possible non-circular bore shapes can be produced. In one embodiment, the control of the feed force is carried out so that the feed force or the contact pressure during a full rotation of the honing tool to the tool axis in a predetermined axial bore area more than two, in particular more than four local maxima and minima passes. The local maxima or minima result from a periodic or aperiodic change between increase and decrease in the feed force during a tool revolution. For example, consider a 4-way symmetric one Circular form deviation in an axial bore area, the feed force of a honing tool with a single unilaterally arranged cutting group would require four evenly spaced maxima and four intermediate, equally spaced local minimums of the delivery force in one revolution of the honing tool to the quadruple symmetrical shape starting from to produce an ideal circular cylindrical shape. If the control of the honing machine, however, configured so that significantly higher numbers of local maxima and minima are generated, so for example a complex bore cross-sectional shape can be generated, the basic shape of the 4-fold symmetrical shape is similar, but the short-wave diameter or radius variations according to Art superimposed by "harmonics".

In the axial direction of the bore different non-circular and circular axial bore sections can alternate or merge. This can be achieved by simultaneous variation of the feed pressure as a function of the angular position and of the stroke position (axial position). In this way, twisted bore shapes can also be achieved. Such a bore shape results, for example, if a local bulge (local radius enlargement) runs essentially along a helical line in the axial direction on a bore inner surface.

In some variants of the method bores are produced with a bore shape that deviates significantly from a relative to the bore axis two-fold radially symmetrical shape.

The achieved shape deviations from a relative to the bore axis 2-fold radially symmetric shape are well outside the usual, in the honing process considered here applicable tolerances of the cylindricity error, which should be less than 10 microns in many cases.

In preferred variants, the shape deviations from a 2-fold radially symmetrical shape relative to the bore axis correspond to a cylindricity error of significantly more than 10 .mu.m, the cylindricity error preferably being more than 20 .mu.m, in particular between 20 .mu.m and about 60 .mu.m. The cylindricity error is described here by the cylinder shape tolerance. The associated tolerance zone is determined by two to the bore axis and mutually coaxial, the bore inner wall inside or outside touching cylinder, wherein the radial distance between the two cylinders is a measure of the cylinder quality. For the purposes of this application, the cylindricity ΔZ is defined as ΔZ = (D _A -D _I ) / 2, where D _{A is} the diameter of the outer bore contacting cylinder and D _{I is} the diameter of the bore bore internally contacting cylinder.

A suitable for performing the method honing tool has a tool body which defines a tool axis; a cutting group attached to the tool body with at least one cutting material body for material-removing machining of the inner surface; and a cutting group feed system associated with the cutting group for exerting a feed force acting radially to the tool axis on the cutting bodies of the cutting group. The honing tool is associated with an axial guide means for substantially rigid guidance of the axial movement of the honing tool substantially parallel to the bore axis. The axial guide device is designed to receive the reaction force generated by the pressed-on cutting group.

It is possible that the honing tool has a single cutting group with one or more cutting bodies, all on one Side of the honing tool are arranged. Alternatively, it is also possible for the honing tool to have several cutting groups which can be delivered independently of one another, it being ensured by the control that the contact pressure of one cutting group is independent of the contact pressure of other cutting groups arranged in other circumferential positions.

In particular, the honing tool may have a single cutting group, which preferably has an engagement angle of less than 90 °. Such a honing tool can be controlled such that, when the cutting body of this cutting group engages the inner wall of the bore in a peripheral region of at least 270 ° of the circumference, no cutting material bodies are simultaneously in material-removing engagement with the bore wall.

In one embodiment, the Axialführungseinrichtung comprises a set of distributed around the circumference of the honing tool guide rails for axial guidance of the honing tool in the bore, wherein the guide rails are deliverable by means of a guide bar feed device regardless of the cutting material bodies of the cutting group in the direction of the inner surface of the bore. In this case, for example, a gimbal, Doppelkardanisch or floating mounted honing tool with double widening, ie be used with two independently activatable delivery systems. A feed system activates the guide rails that center the honing tool in the hole. The other feed system activates a cutting group mounted on one side of the honing tool, which causes the locally limited material removal in its pressure angle range. The feed force of the cutting material body of the cutting group, which corresponds to a corresponding contact pressure of the cutting material body, is then controlled as a function of stroke position and / or angular position of the honing tool to along predetermined ranges the circumference and in the axial direction of the bore to effect a targeted material removal. The reaction force of the cutting material body in cutting engagement with the bore inner wall is intercepted on the opposite side from the guide rails without affecting the bore shape. The term "guide rails" in particular comprises strip-shaped guide elements, which ensure the centering. Also differently shaped guide elements should be detected, as far as they fulfill the function of the substantially rigid axial guidance of the honing tool by supporting on the inner wall of the bore.

The cutting group feed system acting on the cutting group can be controlled by a drive mounted in the honing machine, which acts on the cutting material body of the cutting group via a feed linkage or via a gear and determines its delivery force. In this case, the cutting group feed system of the honing tool is designed for transmitting the feed force of a drive arranged outside of the honing tool. It is also possible for the cutting group feed system for the cutting group to have a drive arranged within the honing tool.

A division of the cutting group delivery system into a (coarse) base delivery system and a dynamic fine delivery system is provided in the claimed invention, but is not mandatory. In other systems, the cutting group delivery system is undivided and configured such that the delivery force provided by a drive arranged outside the honing tool, in particular within the honing machine, is transmitted to the cutting group without intermediary drives.

In the feed systems for both the guide rails and for the cutting body of the cutting group hydraulic, electromechanical, piezoelectric, pneumatic and other suitable drives are used.

The substantially rigid axial guidance of the honing tool is achieved in some embodiments in that the axial guiding device comprises at least one guide unit to be arranged outside the bore during honing for substantially rigid guidance of the axial movement of the honing tool. Honing tools with a rigid tool guide can be used. In this case, only the cutting group feed system is needed to operate the cutting group mounted on one side of the honing tool. The reaction forces of the pressed cutting material body are absorbed by the rigid tool guide. In this case honing tools with simple expansion can thus be used.

In the method according to the invention, the complex, non-circular and possibly asymmetrical bore shape is produced by honing, starting from a bore shape produced by a pre-machining step. As a rule, this shaping by honing does not lead to the surface structure desired for the inner surface of the bore, which decisively influences the tribological properties of the inner surface. Therefore, in a preferred embodiment, after the shape-generating honing operation to produce the non-round bore shape, at least one substantially shape-neutral (ie, not substantially changing the macro-shape of the bore) machining operation for machining near-surface areas of the inner surface is performed. This may be, for example, a so-called "plateau honing" in which the tips of the roughness profile are cut to improve the motor enema. A Zwischenhonschritt or a sequence of Zwischenhonen and Plateauhonen is possible. To improve the homogeneity of the substantially shape-neutral processing steps known systems can be used in which by means of a metallic spring or the like, the cutting material body are applied to the inner surface of the bore. In conventional plateau hoist tools, a maximum of 5 to 7 separate cutting material bodies are present, which are supported on a metallic spring system. These systems can also be used in the context of inventive method in the case of form errors of less than about 10 μm. If, however, the form errors (in particular cylindricity errors) of a targeted, non-circularly machined bore are significantly greater, the inner surface is preferably machined with a plurality of relatively moveable, elastically mounted cutting material bodies in the substantially dimensionally neutral machining operation, which has a maximum extent of less in the circumferential direction of the honing tool than 3% of the effective range of the honing tool. The cutting material body can also be very small in the axial direction, for example, their axial length may be less than 10% of the honing tool length. By a honing tool with such highly segmented cutting material groups a surface contact of the small cutting material body is also secured to extremely rough shape honed bore inner surfaces, since the relatively small, elastic mounted cutting material body of the inner contour of the hole can follow while maintaining the flat contact.

A workpiece can be produced with at least one bore having a honed inner surface, wherein the bore in at least one axial bore section has a non-circular-cylindrical bore shape, which deviates significantly from a two-fold radially symmetrical shape relative to the bore axis, and in particular a cylindricity error of more than 20 microns. In particular, the workpiece may be a cylinder block for an internal combustion engine, wherein the bore is a cylinder bore of the cylinder block and the shape deviation is designed so that the cylinder bore in the ready-assembled state or in the operating state of the cylinder block with screwed onto the cylinder block Cylinder head has a cylindricity of less than about 10 microns.

A honing machine suitable for carrying out the method has a feed force control device for controlling the feed force of a cutting group attached to a honing tool as a function of the stroke position and / or the angular position of the honing tool in a bore, wherein the feed force control device is configured or configurable such that the bore receives a non-circular-cylindrical bore shape at least in an axial bore section, which deviates significantly from a 2-fold radially symmetrical shape relative to the bore axis. The feed force control device for controlling the feed force of a cutting group mounted on one side on a honing tool can in particular be configured so that the delivery force during a full rotation of the honing tool around the tool axis in a predetermined axial bore area more than two, in particular more than four local maxima and Minima goes through.

• Fig. 1 zeigt eine schematische Perspektivansicht eines 4-Zylinder-Motorblockes bei der Bearbeitung mit einer Ausführungsform eines erfindungsgemäßen Honwerkzeuges;
• Fig. 2 zeigt eine schrägperspektivische Ansicht einer Ausführungsform eines Honwerkzeuges mit Führungsleisten und einer einseitig an dem Honwerkzeug angebrachten Schneidgruppe mit zwei leistenförmigen Schneidstoffkörpern;
• Fig. 3 zeigt eine schrägperspektivische Ansicht einer anderen Ausführungsform eines erfindungsgemäßen Honwerkzeuges mit einer einseitig angeordneten Schneidgruppe mit zwei leistenförmigen Schneidstoffkörper und einer extern anbringbaren Axialführungseinrichtung;
• Fig. 4 zeigt einen schematischen Querschnitt durch eine Ausführungsform eines erfindungsgemäßen Honwerkzeuges mit Doppelaufweitung, bei dem das Schneidgruppen-Zustellsystem ein Basissystem zur Grobzustellung und ein dynamisches Feinzustellsystem umfasst;
• Fig. 5 zeigt eine schematische schrägperspektivische Ansicht eines Schneidgruppen-Zustellsystems mit einem Basiszustellsystem für die Grobzustellung und einem dynamischen Feinzustellsystem;
• Fig. 6 zeigt schematische Messdiagramme einer zylindrischen Bohrung mit geringem Zylindrizitätsfehler;
• Fig. 7 zeigt schematische Messdiagramme einer Zylinderbohrung mit großem Zylindrizitätsfehler und signifikanter Abweichung von einer 2-zähligen Radialsymmetrie;
• Fig. 8 zeigt schematische Diagramme zur Erläuterung des Zusammenhanges zwischen der Geometrie einer Bohrung mit großem Zylindrizitätsfehler und der zur Erzeugung der unrunden Bohrungsform erforderlichen Variation der Zustellkraft über die Winkelposition einer einseitig an einem Honwerkzeug angebrachten Schneidgruppe;
• Fig. 9 zeigt eine schematische Draufsicht einer Ausführungsform einer Schneidgruppe für die Plateau-Honbearbeitung einer unrunden Zylinderbohrung mit großem Zylindrizitätsfehler; und
• Fig. 10 zeigt einen schematischen Querschnitt durch die Schneidgruppe in Fig. 9.

Preferred embodiments will be explained with reference to the accompanying drawings.

• Fig. 1 shows a schematic perspective view of a 4-cylinder engine block during machining with an embodiment of a honing tool according to the invention;
• Fig. 2 shows an oblique perspective view of an embodiment of a honing tool with guide rails and a one-sided attached to the honing tool cutting group with two strip-shaped Schneidstoffkörpern;
• Fig. 3 shows an oblique perspective view of another embodiment of a honing tool according to the invention with a cutting group arranged on one side with two strip-shaped cutting material body and an externally attachable Axialführungseinrichtung;
• Fig. 4 shows a schematic cross-section through an embodiment of a double widening honing tool according to the invention, in which the cutting group delivery system comprises a basic roughing system and a dynamic fine delivery system;
• Fig. 5 shows a schematic oblique perspective view of a cutting group delivery system with a base delivery system for coarse delivery and a dynamic fine delivery system;
• Fig. 6 shows schematic measurement diagrams of a cylindrical bore with low cylindricity error;
• Fig. 7 shows schematic measurement diagrams of a cylinder bore with large cylindricity and significant deviation from a 2-fold radial symmetry;
• Fig. 8 shows schematic diagrams for explaining the relationship between the geometry of a bore with large cylindricity and the required for generating the non-circular shape bore variation of the delivery force on the angular position of a one-sided attached to a honing tool cutting group;
• Fig. 9 shows a schematic plan view of an embodiment of a cutting group for the plateau Honbearbeitung a non-circular cylinder bore with large cylindricity; and
• Fig. 10 shows a schematic cross section through the cutting group in Fig. 9 ,

Fig. 1 shows a schematic, oblique perspective view of a cylinder block (engine block) 100 for a 4-cylinder internal combustion engine. In the cylinder block consisting of a cast material or a light metal material, four axially parallel cylinder bores 101, 102, 103, 104 are arranged at equal distances in series next to one another such that their central bore axes 111 lie in a common plane (cylinder plane 112). From the upper side of the cylinder block are provided internally threaded bores 115 axially parallel to the cylinder head bores so that in each case four of these bores are distributed uniformly around the circumference of a cylinder bore. The holes 115 are used to receive cylinder head bolts, with the help of which, after completion of the processing of the cylinder block of the associated cylinder head is screwed onto the cylinder block 100 with the interposition of a cylinder head gasket.

It can be seen that the cylinder block 100 is a structurally nonuniform workpiece, in which in particular each of the cylinder bores 101-104 has a different workpiece environment, in particular with regard to the wall thickness in the region of the cylinder bores and also by different connections to the coolant channels of the engine block internal cooling system. For example, the inner cylinder bores 102 and 103 of the second and third cylinders each have two adjacent cylinder bores in the cylinder plane, while the outer cylinder bores (cylinders 1 and 4) have only one inner adjacent cylinder bore have and border on the opposite side to thicker wall sections of the workpiece.

The workpiece 100 formed by the cylinder block is clamped on a work table (not shown) of a honing machine, not shown, with two honing spindles, wherein only one honing spindle 120 is shown. The cylinder surfaces formed by the inner surfaces 130 of the cylinder bores are subjected to a quality-determining finishing on the honing machine, in which both the macro-shape of the cylinder surfaces, as well as their surface topography is produced by suitable honing processes. The honing machine comprises for each of its honing spindles a spindle motor for rotating the honing spindle about its longitudinal axis and a lifting drive for generating a vertical movement of the honing spindle when inserting the honing tool into the workpiece or when pulling out of the workpiece. The lifting drive is controlled during machining so that the honing tool executes a vertical reciprocating movement within the bore, which is superimposed on the rotational movement of the workpiece (see arrows).

At the lower end of the honing spindle, an embodiment of a honing tool 150 according to the invention is coupled, which is a gimbal-mounted honing tool with double widening. The honing tool has a tool body 155 which carries on one side of its circumference a cutting group 160 formed by a single honing stone, which can be delivered or withdrawn in the radial direction to the bore inner wall by means of a not-shown cutting group delivery system. Furthermore, a set of unevenly distributed around the circumference of the honing tool guide rails 170 is provided on the tool body, which are delivered by means of a guide rail feed system regardless of the cutting group 160 in the direction of the inner surface of the bore can. When the substantially non-cutting guide rails abut against the inner surface of the bore, substantially rigid guidance of the axial movement of the honing tool within the bore results parallel to the bore axis 113, so that the guide rails form an axial guide device for the honing tool.

The feed movement of both the guide rails and the cutting group and the respectively applied feed force are independently controlled by means of a Zustellkraft control device 180 of the honing machine, in particular the feed force of the cutting group 160 highly dynamically depending on the stroke position of the honing tool (measured along the bore axis) and the angular position of the cutting group (in the circumferential direction) can be selectively varied in rapid change.

The Fig. 2 to 4 show elements of various embodiments of inventive honing tools, which are designed especially for the processing of cylinder surfaces in cylinder blocks. The honing tool 200 in Fig. 2 has arranged on one side of the tool axis 201 cutting group 260 with two peripherally offset on the circumference of the tool body 255 mounted, formed by honing strips cutting material body 261 attack during honing in a pressure angle range 265 of about 45 ° on the bore inner wall. Their axial length is between 30% and 50% of the axial length 266 of the honing tool. Furthermore, the honing tool comprises an integrated axial guide device, which is formed in the example by a number of evenly distributed around the circumference of the honing tool guide rails 270 which are radially deliverable independently of the honing stones 261 of the cutting group 260. The guide rails extend substantially over the entire axial length 266 of the honing tool, the honing stones 261 are in the axial central region (at other embodiments in the lower end region) of the defined by the guide rails support length attached.

The honing tool 300 in Fig. 3 has arranged on one side of the tool axis 301 cutting group 360 with two peripherally offset on the circumference of the tool body 355 mounted, formed by honing strips cutting body 361 attacking during honing in an engagement angle range of about 45 ° on the bore inner wall. Their axial length is between 60% and 80% of the axial length of the honing tool. There are no guide rails. The axial guidance device 370 of the honing tool comprises a guide section 371, which is attached to the spindle-side end of the tool body and has a circular-cylindrical outer surface, which is axially and rotationally guided in a guide unit 372 (upper guide) arranged outside the workpiece and fastened to the honing machine.

Fig. 4 shows a guided perpendicular to the tool axis 401 section through a honing tool 400, which is a variant of the in Fig. 2 shown double-expandable honing tool is. The cutting group 460 mounted on one side of the tool axis 401 comprises two cutter bodies 461, 462 which are arranged offset by approximately 80 ° to 90 ° and can be controlled separately and which define an engagement angle range 465 of approximately 90 °. The integrated axial guide device comprises six guide rails 471-476 distributed around the circumference of the tool body, which can be delivered in the radial direction to the bore inner wall by means of a force-limited guide rail feed system 480, so as to be axially slidable within the tool, but substantially rigid within the bore axis to lead the bore. The guide rails are made of a hard, abrasion-resistant elastomer (Vulkollan ® here), have a substantially smooth pressure surface and exercise in the axially oscillating and rotating Movement of the honing tool in the cylinder bore no material removal.

The cutting group 460 is mounted on one side of the honing tool. This means, in particular, that all of the cutting material bodies standing in honing processing in material-removing engagement with the bore inner wall lie on the same side of the tool bisecting tool level 490, which contains the tool axis 401 and is perpendicular to the bisector of the cutting group 460. On the side of the cutting group is essentially only one, mounted between the cutting material body guide rails 471 and a part of the vertically aligned guide rails. On the side diametrically opposite the cutting group with respect to the tool axis 401, a high spatial density of guide rails corresponding to a comparatively large contact surface is provided, so that the opposing force acting on the opposite guide rails 473-475 when the cutting material body presses against the bore inner wall converts a relatively low contact pressure of these guide rails on the bore inner wall, whereby a bore wall gentle, smooth axial guidance of the honing tool is achieved within the bore.

The feed movement of the cutting material body 461 of the cutting group 460 is controlled by means of a cutting group feed system 450, which is subdivided into two independently operable subsystems. A Basiszustellsystem 452 has a relatively large displacement of several millimeters and serves to deliver the radial outer surfaces of the Schneidstoffkörper 461, 462 after applying the guide rails to the bore inner wall to a few microns to the bore inner wall. The radial position of support elements 453 of the base delivery system achieved by this adjustment movement remains unchanged during honing. The mechanical drive for the Base delivery system is seated in the honing machine, the drive movement is by suitable feed elements including a coaxially seated in the tool body feed cone (see. Fig. 5 ) causes.

Furthermore, a dynamic fine delivery system 454 is provided which, starting from the radial position predetermined by the base delivery system, permits radial delivery or radial retraction of the cutting material bodies. Piezoelectric elements 455, which are mounted between the carrier elements 453 of the base delivery system and the cutting bodies, and which can be controlled by applying an electrical voltage so as to enable a dynamic change in distance between the carrier elements of the base delivery system and the cutting bodies, serve as the drive of the fine delivery system. The characterized by low moving masses Feinzustellsystem is designed in this way highly dynamic and allows during a single revolution of the honing tool several, eg between two and ten, periodic or aperiodic change between increase and decrease in the delivery force to complex curved and with a variety of local maxima and minima to create contours provided the bore inner wall with high accuracy.

The piezoelectric or otherwise driven fine delivery system can also be arranged above the Zustellkonus between this and the coarse delivery system. In this position, the fine delivery system can be arranged both on the rotating part of the honing spindle, as well as on the non-rotating part of the honing machine.

In Fig. 5 Further details of a basic delivery system and a fine delivery system are shown schematically, which also in the honing tools according to Fig. 2 or Fig. 4 can be used in the illustrated or modified manner. The one-sided to the tool axis In this example, 501 cutting group 560 attached to the honing tool comprises five axially parallel honing strips 561, which are mounted on a common carrier 562 and overall define an engagement angle of approximately 30 °. The BasisZustellsystem 552 of the cutting group delivery system 550 includes a parallel to the tool axis axially movable cone 554. This works with a radially movable mounted in the tool body support member 553, which has a tapered inclined surface, so that in the manner of a wedge drive axial movement of the cone 554 is converted into a radial movement of the cutting group. With the help of this base delivery system, the support member 553 can be adjusted against the force of a radially inwardly acting return spring to a predetermined radial position.

On the radial outer side of the carrier element 553, a piezoelectric drive element 555 of the fine delivery system 556 is attached, which is arranged between the carrier element 553 and the carrier element 562 for the honing stones. The radial thickness of the piezoelectric actuator 555 is determined by applying appropriate control voltages provided by the controller 180 (FIG. Fig. 1 ) are provided, radially adjustable in an adjustment range of about 20 microns to about 60 microns to possibly allow a quick change of the delivery pressure of the cutting material body.

Based on Fig. 6 to 8 Now applications of the honing tools or the honing machine will be explained using the example of the processing of the cylinder surfaces of a cylinder block. To characterize the macro-shape of a cylinder surface shows Fig. 6 (a) a schematic peripheral record and Fig. 6 (b) a schematic longitudinal section of the dimensions of a cylinder surface. For circumferential writing, radial distances of the bore inner wall from the bore axis BA are dependent on the circumferential position along the Bore inside surface shown, wherein the zero point of the circumferential direction and the 180 ° position in the cylinder axis defined by the bore axes of the cylinder 112 (see. Fig. 1 ) and the 90 ° and 270 ° positions represent the perpendicular regions near the front and rear broad sides of the cylinder head. The curves R _O , R _M and R _U represent the radius in the vicinity of the upper inlet opening of the cylinder bore (R _O ), in the axial center region of the cylinder bore (R _M ) and in the vicinity of the lower end of the cylinder bore (R _U ). In the manner known to those skilled in the circulating measurement curves of the circumferential letter are each related to a zero line lying concentrically to the bore axis, which in the representation in Fig. 8 each dashed line is drawn. The same radial scale in the radial direction serves for all measuring curves. The longitudinal letters in Fig. 6 (b) each show the course of the generatrices (parallel to the bore axis) in the selected peripheral areas at 0 °, 90 °, 180 ° and 270 °.

The schematic Messschriebe in Fig. 6 represent at the selected resolution, a substantially circular cylindrical shape of the bore inner surface with a cylindricity .DELTA.Z of about 10 microns. Such a relatively small cylindricity error is considered in some applications to be sufficient to ensure adequate sealing during operation of the internal combustion engine in conjunction with substantially circular piston rings over the entire length of the cylinder.

Such, substantially circular cylindrical bore shape is thus in the operating condition of the engine, ie in the warm operating condition with screwed cylinder head, strive for. However, it has been shown that this goal of a "use optimal bore geometry" can not be achieved with sufficient precision, if in the honing process, ie without screwed cylinder head and possibly at lower, of the operating temperatures significantly different temperatures, a substantially circular cylindrical bore shape is generated. Rather, elastic deformation caused by screwing the cylinder head to the cylinder block and by increased temperatures during operation lead to significant deviations from the desired circular cylindrical shape. To avoid these problems, the procedure is as follows in one embodiment of a method according to the invention.

In a first method step, a cylinder block of a series of cylinder blocks to be manufactured is clamped in the honing machine. Then, the cylinder block is braced by means of a tensioning device, which essentially simulates the clamping forces acting on the cylinder block when a cylinder head is screwed onto the cylinder block. As a result, the stress state of the cylinder block in the operating state can be approximately adjusted. For this purpose, a clamping device according to the patent DE 28 10 322 C2 are used, the content of which is incorporated herein by reference. Alternatively, a bracing can be made, as in the Japanese patent application JP 11 267960 is described. If desired, the cylinder block can still be heated significantly above ambient temperature to generally simulate the conditions of a warm, fully assembled hull engine.

In the next step, the cylinder bores of the strained and possibly heated cylinder block are honed in a single-stage or multi-stage honing process to obtain a possible circular cylindrical bore shape. In typical process variants, a cylinder shape error ΔZ of less than 10 μm is achieved in this phase of machining. Typical calipers used to determine the shape of the bore can be found in Fig. 6 show characteristics shown. A typical machined cylinder bore has after this manufacturing step in all axial positions a substantially circular circumference with a surface contour without pronounced maxima, minima or inflection points and in the axial direction (longitudinal) at different positions along the circumference virtually no or only a very slight, gradual variation of the radius or of diameter ( Fig. 6 (b) ).

After completion of this phase of processing, the clamping device is removed, so that the elastic deformation produced by the clamping device and possibly by the action of temperature are reduced in the workpiece and this assumes a relaxed state.

In this relaxed state, the bore geometry of the honed cylinder bores is measured separately for each of the cylinder bores. Fig. 7 shows an example of the corresponding Fig. 6 recorded measurement records in the circumferential direction ( Fig. 7a ) and in the axial direction ( Fig. 7b ) of the marginal fourth cylinder bore 104 in Fig. 1 , It can be seen that the hole in the vicinity of the cylinder head side inlet side (represented by the curve R _O ) has an approximately 2-fold radial symmetry about the bore axis BA, in which the largest diameter obliquely to the cylinder plane in the range of the circumferential angle 135 ° or. 315 °, while perpendicular to it (corresponding to angular positions 45 ° and 225 °) also form local maxima of the radius, but which lie at smaller absolute radius values. The approximately 2-fold symmetrical basic shape are superimposed on smaller radius fluctuations, for example in the range of 180 °.

In the axial center region of the bore (curve R _M ) results in a much more complex relationship between circumferential position and bore radius or bore diameter. In the example shown arise in the circumferential direction about eight local maxima of the inner radius, which are separated by local minima of the inner radius. The largest radii tend to remain inclined to the cylinder plane.

In the cylinder head end region facing away from the end of the cylinder bore, represented by the curve R _U , the bore cross section is also asymmetrical, but the 2-fold radial symmetry still indicated at the cylinder head end no longer dominates and dominates an almost completely irregular bore cross-sectional shape.

In the axial direction of the bore inner wall also result in significant variations in the bore radius. While along the surface line at 0 °, the radius decreases to the lower end of the bore, the bore wall on the opposite side (at 180 °) is significantly distorted in the axial direction, so that there is a strong minimum radius near the entrance opening and in the lower third, while in the middle region the radius becomes maximum. If, on the other hand, a section perpendicular to the cylinder plane (at 90 ° and 270 °) results in minimal radii near the upper inlet opening, while in the lower third the bore radius assumes a local maximum.

In this example, the asymmetrically warped hole shape that can be characterized in this way corresponds to a cylindricity ΔZ of between 30 μm and 40 μm. This complex and asymmetrically deformed bore geometry will be deformed when placing and screwing a cylinder head and heating the resulting hull motor in the range of operating temperatures back to a largely cylindrical bore shape, as shown by Fig. 6 was explained.

In the method variant described here now the complex deformed hole geometry after removal of the clamping device In order to determine in this way the local radii of the distorted shape as a function of the axial position and the circumferential position. In this way, a data set is determined, which represents the relaxation, complex and asymmetrically deformed bore geometry. This complex bore shape corresponds to a "negative mold" that is to be achieved in the machining of the other cylinder blocks of the series by shaping honing machining, if the machined cylinder bores in the mounted state of the engine should have a largely cylindrical shape with low cylindricity.

The geometry data representing the complex unsymmetrical bore shape separately for each cylinder bore is stored in the controller 180 in a suitable form. During honing, they can be compared with measured values of a dimensional measuring system with tool-internal sensors (eg air measuring system) and converted into corresponding data for the feed pressure with which a one-sided attached to a honing tool cutting group must be belaufschlagt to axially rigid guide the honing tool and control of Adjusting force of the cutting group as a function of the axial position and the angular position of the honing tool to achieve the complex asymmetrically shaped bore shape.

On the basis of the obtained data set, subsequent cylinder blocks of the series are now processed by means of shaping honing. In the case of series processing, it is no longer necessary to clamp and / or heat up the individual cylinder blocks for honing machining. Rather, by honing on stress-free workpieces based Fig. 7 exemplified negative shape of the cylinder bore generated by means of the data stored in the control device.

Fig. 8 shows exemplary for two axial positions of the cylinder (represented by the curves R _O and R _M in Fig. 8 (a) ) the stroke and rotation angle-dependent radius profile of the bore (in Fig. 8 (a) ) and in Fig. 8 (b) the course of the feed force F on the rotation angle φ, respectively in the corresponding axial heights. In Fig. 8 (b) The dashed curve F _{O represents} the variation of the feed force over the rotation angle that would be required when a honing tool whose cutting group rotates in the upper end portion of the cylinder bore processes the inner surface. The solid line F _M corresponds to the temporal variation or angle variation that would be required in the middle region of the bore (R _M ). While the approximately, but not exactly 2-fold radially symmetrical bore cross-sectional shape at the upper end can be achieved essentially by a variation of the delivery force with two local maxima and intermediate local minima and a short-term Zustellkraftspitze at 180 °, the shaping honing in the central region of the bore (curve R _M ) in a single revolution of the honing tool a multiple, rapid change between increase and decrease of the delivery force, which leads to the formation of six to eight local minima and local maxima in one full revolution. Some local maxima are in Fig. 8 (b) indicated by arrows and correspond substantially to the local radii maxima of the curve R _M. If, during honing, the honing tool is moved in an axially oscillating manner and at the same time rotated about its tool axis, the actual time profile of the advancing force acting on the cutting group results from a superimposition of the profiles explained here for simplification, whereby the strong variation in the axial direction (FIG. Fig. 7 (b) ) in a contribution to the variation of the delivery force.

After performing the mold honing, the cylinder bore can be measured by means of a shape measuring system. A possibly still existing, measured difference of the actual shape to the desired shape can be used to correct the infeed system as a function of stroke position and angle of rotation be used. In particular, during and / or after a shape-generating honing operation, a measurement of the bore shape can thus be carried out for determining actual shape values, and a difference between the shape Is values and the desired shape can be processed to correct the control of the delivery force. By this control loop improved accuracy of the Formhonprozesses can be achieved.

In general, the material-removing machining steps for generating the complex, non-circular and possibly asymmetrical bore shapes are produced with the aid of a honing tool (or with the aid of a plurality of honing tools used in succession), the cutting group of these honing tools being designed for a substantial material removal, around the macro-shape of the bore in the desired manner. As a result, the microstructure of the machined inner bore surface may not meet the operational requirements for surface roughness and / or surface texture. Therefore, in preferred processes, after the predetermined processing steps, at least one substantially shape-neutral, i. the macro-shape of the bore is performed essentially non-altering machining operation. In this case, honing tools can be used with correspondingly adapted to the surface requirements grain of the cutting material body and / or brushing or Plateauhonwerkzeuge and / or other surface structure changing processing tools, such as non-contact tools, such as laser and / or water jet generator, the surface structure of the bore inner surface without affecting the Can change macro shape.

The FIGS. 9 and 10 show in plan view and cross-section, a cutting group 960, which is optimized for a "plateau honing" unsymmetrical bore shapes to those after the shaping honing To cut still existing peaks of the roughness profile and thereby increase the bearing ratio of the surface. Since in the previous processing steps a bore shape with possibly very small local radii in the range of local minima or maxima can be generated, a honing tool is provided whose cutting group 960 is capable of the corrugated surface of a targeted non-circularly machined bore with a cylindricity of to process substantially uniformly over 10 μm. For this purpose, a more segmented honing system is provided, in which the cutting material bodies 961 formed by honing stone segments are applied to an inherently elastic base body 965, for example a plate made of a rubber-like material. This intrinsically elastic base body is applied to the actual base material 966 of the honing stone, for example a support made of steel, copper or the like, by gluing or in some other way. In the example, the square honing stone segments 961 have an extension of 10mm x 10mm. Thus, in the case of plateau honing, a planar contact of the segments with the bore of the shape is ensured, since the cutting material bodies 961 can adapt to the wavy course of the bore inner surface under local elastic deformation of the elastic base body 965.

Honing tools with one or more such cutting groups can be used regardless of the other features of the invention and the method described herein in other honing process for the final machining of holes in workpieces.

Claims (14)

1. Method for the honing of the inner face of a bore in a workpiece, in particular for the honing of a cylinder running face in the production of cylinder blocks for internal combustion engines, wherein a honing tool is driven axially movably and so as to rotate about its tool axis within the bore, and a cutting group (160, 260, 460, 560), attached to the honing tool and having at least one cutting material body for the material-removing machining of the inner face, is pressed with a feed force onto the inner face, essentially rigid guidance of the axial movement of the honing tool takes place for generating an axial movement of the honing tool essentially parallel to the bore axis of the bore, the guidance of the axial movement serving for absorbing the reaction force generated by the pressed-on cutting group, and time-asymmetric control of the feed force of the cutting group is carried out as a function of the angular position and, if appropriate, of the stroke position of the honing tool, in such a way that the bore acquires a non-circular-cylindrical bore shape at least in one axial bore portion,
   a honing tool being used which has a single cutting group with one or more cutting material bodies which are all arranged on one side of the honing tool, or a honing tool being used which has a plurality of cutting groups feedable independently of one another, the control ensuring that the pressure force of one cutting group is independent of the pressure force of other cutting groups arranged in other circumferential positions,
   the cutting group being fed by means of a basic feed system (452, 552) into a predeterminable radial position and radial feed or radial withdrawal of the cutting group taking place, from the radial position predetermined by the basic feed system, by means of a dynamic precision feed system (454, 556) actuatable independently of the basic feed system.
2. Method according to Claim 1, wherein the precision feed system generates during a single revolution on the honing tool a plurality of, in particular between two and ten, periodic or aperiodic changes between an increase and a decrease in the feed force.
3. Method according to Claim 1 or 2, wherein the basic feed system (452, 552) is actuated via a preferably mechanical or hydraulic drive arranged outside the honing tool, which drive moves a cone movable parallel to the tool axis, the precision feed system (454, 556) being actuated via a drive (455, 555) actuated electromechanically or piezoelectrically, the drive of the precision feed system preferably being arranged inside the honing tool or on a rotating part of a honing spindle, carrying the honing tool, above the cone.
4. Method according to one of the preceding claims, wherein, for the essentially rigid guidance of the axial movement, the honing tool is supported within the bore axially slideably and so as to be essentially immovable transversely to the tool axis, a honing tool preferably being used which comprises guide strips for the axial guidance of the honing tool in the bore, which guide strips can be fed in the direction of the inner face of the bore preferably independently of the cutting group, the essentially rigid guidance of the axial movement being achieved in that, during the movement of the honing tool in the bore, the guide strips are pressed onto the inner face of the bore.
5. Method according to one of the preceding claims, wherein a non-circular-cylindrical bore shape is generated which deviates significantly from a shape which is radially symmetrical to two digits in relation to the bore axis, dimensional deviations which correspond to a cylindricity error ΔZ of more than 10 µm preferably being generated on the bore, the cylindricity error ΔZ preferably being more than 20 µm, in particular between 20 µm and approximately 60 µm, the cylindricity error being defined as ΔZ=(D_A-D_I)/2, D_A being the diameter of a cylinder touching the inner face of the bore on the outside, and D_I being the diameter of a cylinder touching the inner face of the bore on the inside.
6. Method according to one of the preceding claims, wherein, after the shape-generating honing operation for generating the non-round bore shape, at least one essentially shape-neutral machining operation is carried out for machining near-surface regions of the inner face, the shape-neutral machining operation preferably being plateau-honing machining wherein the tips of the roughness profile generated as a result of the preceding honing operations are cut and/or, preferably during the essentially shape-neutral machining operation, the inner face of the bore is machined by means of a multiplicity of elastically mounted cutting material bodies movable in relation to one another.
7. Method according to one of the preceding claims, wherein, during and/or after a shape-generating honing operation, measurement of the bore shape is carried out to determine shape actual values, and a difference between the shape actual values and the desired shape is processed in order to correct the control of the feed force.
8. Honing tool, in particular for carrying out the method according to one of the preceding claims, with a tool body which defines a tool axis (201, 401, 501), with a cutting group (160, 260, 460, 560) attached to the tool body and having at least one cutting material body for material-removing machining of the inner face, and
   with a cutting-group feed system (450, 550), assigned to the cutting group, for applying a feed force acting radially to the tool axis to the cutting material bodies of the cutting group,
   the honing tool having a single cutting group with one or more cutting material bodies which are arranged solely on one side of the honing tool, or the honing tool having a plurality of cutting groups which are feedable independently of one another and in which the pressure force of one cutting group can be controlled independently of the pressure force of other cutting groups arranged in other circumferential positions,
   the honing tool being assigned an axial guide device (170, 270, 470) for the essentially rigid guidance of the axial movement of the honing tool essentially parallel to the bore axis, the axial guide device being designed for absorbing the reaction force generated by a pressed-on cutting group,
   characterized in that the cutting-group feed system (450, 550) acting on the cutting group comprises a combination of a basic feed system (452, 552) with a dynamic precision feed system (454, 556), the basic feed system (452, 552) being designed such that, in the case of rough feed, the material-removing regions of the cutting material bodies can be brought with the aid of the basic feed system nearly to the inner face of the bore over a long first adjustment travel up to a small clearance or up to contact, and the dynamic precision feed system (454, 556) being designed for generating brief changes in the feed pressure and second adjustment travels short in relation to the first adjustment travel.
9. Honing tool according to Claim 8, wherein the first adjustment travel of the basic feed system (452, 552) amounts to at least one millimetre, preferably to at least 4 mm, and the second adjustment travel of the precision feed system (454, 556) lies in the region below 100 µm, in particular in the range of between 20 µm and 60 µm in radius.
10. Honing tool according to either one of Claims 8 and 9, wherein the basic feed system (452, 552) of the honing tool is designed for transmitting the feed force of a preferably mechanical or hydraulic drive arranged outside the honing tool, and the precision feed system (454, 556) possesses at least one preferably electromechanical or piezoelectric drive (455, 555) arranged inside the honing tool.
11. Honing tool according to one of Claims 8 to 10, wherein electrically activatable, in particular piezoelectric elements (455) are provided as the drive of the precision feed system (454) and are mounted between carrier elements (453) of the basic feed system and the cutting material bodies (461, 462) and can be activated by the application of an electric voltage such that they bring about a dynamic change in distance between the carrier elements of the basic feed system and the cutting material body.
12. Honing tool according to either one of Claims 8 and 9, wherein the basic feed system is designed for transmitting the feed force of a preferably mechanical or hydraulic drive arranged outside the honing tool and has a cone movable parallel to the tool axis, and a precision feed system driven piezoelectrically or in another way is arranged above the cone between the latter and the basic feed system.
13. Honing tool according to either one of Claims 8 and 9, wherein the honing tool is designed for coupling to a honing spindle, and wherein the precision feed system is arranged on a rotating part of the honing spindle.
14. Honing tool according to one of Claims 9 to 12, wherein the axial guide device comprises guide strips (170, 270, 471 - 476) for the axial guidance of the honing tool in the bore, the guide strips preferably being capable of being fed in the direction of the inner face of the bore by means of a guide-strip feed device (480), independently of the cutting group.

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