Honing tool

Abstract

Honing tool (100) for machining a bore in a workpiece, comprising: a tool body (110) defining a tool axis (112); at least one cutting material body (180) which can be fed radially to the tool axis (112) in the direction of an inner surface of the bore by means of a feed system, and at least one guide bar (120-1, 120-2) arranged on the circumference of the tool body (110) for guiding the honing tool (100) in the bore, wherein the guide bar (120-1, 120-2) is replaceable, characterized in that the tool body (110) has on its circumference for the at least one guide rail (120-1, 120-2) a receiving groove (130-1, 130-2) running parallel to the tool axis (112) with a receiving cross-section which is delimited by two or more flat surfaces (132, 135) running parallel to the tool axis (112); the receiving groove (130-1, 130-2) has an axial end surface (136) at at least one axial end, which is suitable as an axial stop for the guide strip (120-1, 120-2) to be received in the receiving groove (130-1, 130-2); a guide strip (120-1, 120-2) received in the receiving groove (130-1, 130-2) has, on its outer side facing away from the tool body (110), a guide surface (122-1, 122-2) not interrupted by a bore for contact with the inner surface of the bore and, on a side facing the tool body (110), at least two flat surfaces (124-1, 124-2, 125, 126) for surface contact with corresponding flat surfaces (132, 135) of the receiving groove (130-1, 130-2); and a fixing device (150) which can be releasably connected to the tool body is provided for fixing the guide bar (120-1, 120-2) in the receiving groove (130-1, 130-2).

Description

FIELD OF APPLICATION AND STATE OF THE ART

[0001] The invention relates to a honing tool for machining a bore in a workpiece according to the preamble of claim 1.

[0002] The quality-determining final machining of tribologically stressed inner surfaces of bores, such as cylinder bores in cylinder blocks (cylinder crankcases) or cylinder liners, is generally carried out by honing. Honing is a machining process with geometrically indeterminate cutting edges, which is carried out using an expandable honing tool. A honing tool has a tool body and at least one cutting material body which can be fed radially to the tool axis towards an inner surface of the bore using a feed system. In a typical honing operation, the honing tool is moved back and forth within the bore to be machined in the axial direction of the bore and simultaneously rotated at a suitable speed to generate a rotary movement superimposed on the reciprocating movement.The cutting tool body (one or more) attached to the honing tool is pressed against the inner surface to be machined via the feed system with a feed force acting radially to the tool axis. Honing typically creates a cross-ground pattern on the inner surface, typical of honing, with intersecting machining marks, also known as "honing marks."

[0003] Honing tools are more or less bore-filling tools. A typical honing tool has one or more guide pads. Guide pads on honing tools are designed to define a guide diameter with their radially outer guide surface, which is usually slightly smaller than the inner diameter of the bore to be machined.

[0004] Single-stone honing tools, which have only a single adjustable cutting material body in the form of a honing stone and are typically used for relatively small bore diameters, often feature two circumferentially offset guide stones to support the honing tool on the inside of the bore, opposite the honing stone, during honing. Multi-stone honing tools are also available with two or more (e.g., four, six, or eight) radially adjustable cutting material bodies distributed around the circumference of the tool body.

[0005] To insert the honing tool, the cutting material bodies (one or more) are retracted radially so that their abrasive outer surfaces are retracted relative to the guide surfaces or the guide diameter.

[0006] In multi-block honing tools, the cutting tool bodies are then advanced radially outward for the honing operation, so that only the cutting tool bodies engage the inner surface of the bore. The outer surfaces of the cutting tool bodies, advanced to their maximum outward position, define a honing diameter that is typically a few hundredths of a millimeter larger than the guide diameter. In single-block honing tools, the cutting tool body, together with the guide pads, determine the honing diameter. The cutting tool body and the guide pads are in "engagement" together. Therefore, special attention must be paid to guide pad wear.

[0007] Guide rails are usually made of a wear-resistant material to withstand a variety of insertion and machining operations and / or machining operations without damage or substantial material abrasion. However, after extended use, guide rails may become worn and require replacement.

[0008] Generic honing tools are characterized by the fact that they have one or more guide rails that are attached to the tool body in a replaceable or interchangeable manner. This makes them easier to repair and maintain than honing tools where, for example, the guide rails are soldered on and therefore not easily replaceable.

[0009] CN 2 01 115 927 Y describes a honing tool with replaceable guide rails that are attached to the tool body with screws. The guide rails are provided with mounting holes extending from the guide surface inward for the mounting screws to pass through.

[0010] KR 2013 0 122 838 A describes a honing tool with replaceable guide rails in the form of round bars, each of which is inserted axially into an axially extending cylindrical receiving opening and then secured against falling out with a retaining plate screwed into the front end. The guide rails are designed to be able to rotate around their axes in the receiving openings to reduce guide rail wear.

[0011] DE 103 41 991 A1 discloses a honing tool with a tool body to which guide rails and honing stones are mounted radially movable and parallel to a rotational axis of the tool body. The guide rails define a guide area, while the honing stones define a working area that lies at least partially outside the guide area. An actuating device is provided for moving the honing stones in the radial direction. Furthermore, a control device is provided, which is at least temporarily coupled to this actuating device and is movably configured on the tool body for moving the guide rails in the radial direction against a preload applied by a preload device between a functional position and a rest position.The guide rails are located in longitudinal slots running parallel to the axis of rotation, which extend radially from an inner through-opening for the actuating device to the outer circumference.

[0012] DE 40 20 097 C1 discloses a honing tool with a honing stone holder. A face of the honing stone holder, associated with the free end of a tool shank, faces a guide bar, from which it is spaced a certain distance. The guide bar is formed as part of a ring extending around the circumference of the tool shank. This ring is screwed onto an external thread in the area of the free end of the tool shank. By screwing it more or less tightly, the distance between the stop surface of the guide bar and the opposite stop surface of the tool shank can be adjusted. TASK AND SOLUTION

[0013] It is an object of the invention to provide a generic honing tool having one or more guide rails that are easily replaceable for an operator and offer a secure guiding function when the honing tool is used as intended.

[0014] This object is achieved by a honing tool having the features of claim 1. Advantageous further developments are specified in the dependent claims. The wording of all claims is incorporated into the description by reference.

[0015] The honing tool is designed for machining a bore in a workpiece and has a tool body that defines a tool axis. When the honing tool is used as intended, the honing tool ideally rotates around the tool axis. The honing tool comprises at least one cutting material body that can be fed radially to the tool axis towards an inner surface of the bore by means of a feed system. A cutting material body consists of an abrasive material that has irregularly shaped cutting grains that are bound in a bond. This enables material removal with geometrically undefined cutting edges. Bar-shaped cutting bodies whose length in the axial direction is greater than their width measured in the circumferential direction are also referred to as “honing stones”. Furthermore, at least one guide bar is arranged on the circumference of the tool body, which is intended to guide the honing tool in the bore. The guide bar is replaceable orReplaceable. "Replaceable" or "interchangeable" in the context of this application means that a non-destructively removable fastening is provided for attaching the guide rails to the tool body. This results in improved ease of repair and maintenance compared to honing tools in which the guide rails are attached to the tool body, for example, by soldering.

[0016] The tool body has a receiving groove on its circumference for at least one guide rail, which runs parallel to the tool axis and has a receiving cross-section that is delimited by at least two flat surfaces that run more or less parallel to the tool axis. At least one of these flat surfaces can serve as a contact surface for the guide rail in the circumferential direction and help to precisely define the position of the guide rail in the circumferential direction. The receiving groove also has an axial end surface on at least one axial end. This can serve or be used as an axial stop for the guide rail to be received in the receiving groove, and is therefore suitable as an axial stop. A guide rail received in the receiving groove has a guide surface on its outer side facing away from the tool body, which is intended to make contact with the inside of the bore. This guide surface is not interrupted by a bore.This means that there is no hole for a fastening screw through the guide bar. The guide bar can have a uniform cross-section in the longitudinal direction. This makes it possible to provide a guide bar with a simple geometric shape and high mechanical stability. Furthermore, the guide surface can be designed uniformly over the entire area that potentially comes into contact with the honing tool, thus ensuring gentle guidance on the inside of the bore. On a side facing the tool body, the guide bar has at least two flat surfaces for surface contact with corresponding flat surfaces of the receiving groove. Furthermore, a fixing device that can be detachably connected to the tool body is provided for fixing the guide bar in the receiving groove.The axial end face, against which a corresponding end face of the guide rail inserted into the receiving groove can be placed, allows the axial position of the guide rail in the receiving groove to be defined. A flat surface running parallel to the axis ensures the precise position of the guide rail in the circumferential direction. The receiving groove thus provides a receiving structure with contact surfaces that can, if necessary, determine the position of an inserted guide rail in the axial direction, but especially in the circumferential direction.

[0017] With the aid of the fixing device which can be detachably connected to the tool body, the guide rail can be fixed in the receiving groove in such a way that it is in contact with the radial and / or axial contact surfaces and thus its position on the tool body is fixed.

[0018] The guide rails can be easy to manufacture and highly stable, particularly because no holes are required. The guide rails should be wear-resistant. They can be made of hard metal, for example. Alternatives include guide rails made of polycrystalline diamond (PCD) or silicon nitride, or of a material combination, e.g. with a diamond coating or diamond layer on the guide surface, or of a metal-ceramic composite (cermet). Suitably profiled semi-finished products made of these hard, wear-resistant materials can be used without great technical effort, particularly because no fastening holes need to be drilled into the material. When using the invention, many different guide rail materials are available, from which a choice can be made, for example, depending on the workpiece material to be machined.

[0019] Although it is possible for the honing tool to have only a single guide bar that is relatively wide in the circumferential direction, preferred embodiments provide for the honing tool to have a plurality of guide bars distributed around the circumference of the tool body.

[0020] Preferred embodiments have exactly two guide rails that are arranged circumferentially offset on the tool body.

[0021] In particular, the honing tool can be a single-stone honing tool, which has only a single adjustable cutting material body in the form of a honing stone and is typically used for relatively small bore diameters. These tools feature two circumferentially offset guide stones or two circumferentially offset receiving grooves to support the honing tool on the side opposite the honing stone on the inside of the bore during honing. The practical and economic benefit of the invention is particularly significant for single-stone honing tools, since the guide stones are, by their very nature, usually subject to greater wear than those of multi-stone honing tools and therefore need to be replaced more frequently.

[0022] The fixing device is preferably designed as a clamping device which can be actuated by means of at least one clamping screw. The clamping forces act in such a way that the guide rail can be pressed against the flat surfaces of the receiving groove which serve as contact surfaces. The clamping device preferably comprises precisely two axially offset clamping screws. This allows the clamping forces to be distributed more effectively over the length of the guide rail and axially uneven clamping forces can be avoided. In addition, static overdetermination of the clamping forces is avoided. The clamping force of the clamping device is applied by actuating the clamping screw. Using clamping screws, an operator can therefore very easily attach and fix guide rails in the receiving grooves (one or more) of the tool body or, by loosening the clamping device, release the fixation and remove the guide rails from the receiving grooves.

[0023] According to a further development, (at least) two circumferentially offset receiving grooves are formed on the circumference of the tool body for each receiving a guide rail, wherein the clamping device is arranged in an intermediate region between the receiving grooves. The at least one element of the clamping device arranged in the intermediate region can thus act simultaneously on guide rails in the two laterally adjacent receiving grooves. By actuating a single clamping device, two guide rails can thus be simultaneously secured or clamped in their corresponding receiving grooves. Conversely, when the clamping device is released, two adjacent guide rails are released and can be removed for replacement.

[0024] Preferably, the receiving grooves are open on the mutually facing sides in at least one fixing section. This allows the clamping device to engage particularly effectively on the mutually facing side surfaces of the two adjacent guide rails.

[0025] Preferably, at least one threaded hole for receiving a respective screw of the clamping device is arranged in the intermediate region between the receiving grooves. Usually, two threaded holes, in particular exactly two threaded holes, are provided.

[0026] In some embodiments, the threaded hole is located in the region of a fixing section, and a clamping screw equipped with a screw head is screwed into the threaded hole in the clamping configuration such that the screw head directly engages the facing side surfaces of the guide rails and presses them against the opposite flat surfaces of the receiving grooves. Such a clamping device therefore requires only one or more clamping screws to simultaneously clamp the circumferentially adjacent guide rails in their receiving grooves.

[0027] Preferably, the screw head of the clamping screw has a conical underside facing the threaded section. Its cone angle can be adapted to the orientation of the circumferentially distant flat surfaces of the receiving grooves so that the guide rails inserted into the receiving grooves can be directly attached to the tool body using a clamping screw. The guide rails are clamped in their receiving grooves by the conical surface on the underside of the screw head. With appropriate cone angles on the underside of the screw head, a material-protecting linear contact can be established between the underside of the screw head and the facing side surfaces of the guide rails, allowing sufficiently strong clamping forces to be applied without destroying the guide rails.

[0028] In other embodiments, the clamping device has at least one separate clamping element attachable to the tool body, said element having at least one through-bore for passing the threaded portion of a clamping screw, wherein the clamping element has opposing inclined surfaces for pressing against the mutually facing side surfaces of the guide rails. In this arrangement, the clamping force applied by a clamping screw is thus transmitted indirectly via the separate clamping element to the adjacent guide rails. This enables a particularly gentle, large-area transmission of clamping forces. Clamping screws are therefore provided that do not act directly on the guide rails to be clamped, but rather on the separate clamping element, which then clamps the guide rails firmly in their receiving grooves.

[0029] In some embodiments, the two circumferentially offset receiving grooves are open on the mutually facing sides essentially over their entire length, so that the fixing section extends essentially over the entire length of the adjacent receiving grooves. The length of the fixing section can, for example, be more than 80% or more than 90% of the axial length of the receiving grooves. A single, separate clamping element can then be used, which acts on the guide rails inserted into the receiving grooves essentially over the entire length of the guide rails, thereby achieving a particularly uniform clamping force distribution and thus gentle clamping.

[0030] In other embodiments, a receiving groove has a cross-sectional profile with an internal undercut, particularly a T-profile. If a guide rail to be inserted has a corresponding complementary profile, the guide rail can be inserted axially into the receiving groove and is then automatically secured against falling out in the axial direction.

[0031] From a manufacturing point of view, variants are particularly advantageous in which an associated guide rail is fastened to a separate support, so that a guide rail arrangement formed by the support and the guide rail carried thereby has a cross-sectional profile adapted to the cross-sectional profile of the receiving groove in such a way that the guide rail arrangement can be inserted axially into the receiving groove and is secured against radial falling out due to the undercut.

[0032] Since the guide bar accommodated in the receiving groove is already secured against radial fallout by the cross-sectional shape of the receiving groove and the guide bar / guide bar arrangement, an associated fixing device is not required to fulfill this function. It is therefore sufficient if the fixing device is designed to fix the accommodated guide bar in the axial direction. The fixing device preferably comprises a retaining plate that can be attached to the front of the tool body and closes a front opening of the receiving groove. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Further advantages and aspects of the invention emerge from the claims and from the following description of preferred embodiments of the invention, which are explained below with reference to the figures. Fig. 1 shows a side view of a first embodiment of a single-strip honing tool with two replaceable guide strips from the side of the guide strips; Fig. 2 shows the honing tool from Fig. 1 from the side of the honing stone; Fig. 3 shows an isometric view of the tool body from Fig. 1 with mounting grooves; Fig. 4 shows a section through the honing tool perpendicular to the tool axis from Fig. 1 and Fig. 2 in the area of a clamping screw of a clamping device; Fig. 5 shows a side view of a second embodiment of a single-stone honing tool with two guide stones from the side of the honing stone; Fig. 6 shows the honing tool from Fig. 5 from the side of the guide rails; Fig. Figure 7 shows an isometric view of the tool body of the honing tool of Fig. 5 and Fig. 6 with one-sided open grooves for the guide rails; Fig. 8 shows a section through the honing tool oriented perpendicular to the tool axis of the Fig. 5 and Fig. 6 in the area of a clamping screw; Fig. 9 shows a side view of a third embodiment of a single-stone honing tool from the side of the honing stone; Fig. 10 shows a side view of the honing tool from Fig. 9 from the side of the guide rails; Fig. 11 shows an isometric view of the tool body of the honing tool of the Fig. 9 and Fig. 10; Fig. 12 shows a section through the honing tool perpendicular to the tool axis of the Fig. 9 and Fig. 10; Fig. 13 shows an axially parallel section through the honing tool in the area of the front end; Fig. 14 shows an isometric view of a fourth embodiment of a single-bar honing tool; and Fig. 15 shows a section through the honing tool perpendicular to the tool axis from Fig. 14. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] Based on the Fig. 1 to 4, a first embodiment of a honing tool 100 in the form of a single-bar honing tool 100 is described. The honing tool has a tool body 110, which is made from a single piece of round steel and defines a tool axis 112, which represents the longitudinal center axis of the tool body. Using a connecting section 190 with a thicker diameter, the honing tool can be coupled to the work spindle or a drive rod of a honing machine.

[0035] In the end of the tool body facing away from the spindle there is a cutting area in which a single radially adjustable honing stone 180 is arranged, which serves as a cutting material body and has an axial length that is approximately 30% to 50% of the length of the tool body.

[0036] Inside the tool body, there is a guide opening 114 defined by plane-parallel sides, into which a flat feed element of the feed system, formed by a piece of flat steel, is inserted. The feed element has an inclined surface 118 in the area of the honing stone (see Fig. Fig. 13), which interacts with an inclined surface on the support of the honing stone 180 in the manner of a wedge drive in order to convert an axial feed movement of the feed element into a radial feed movement of the honing stone.

[0037] On the rear side of the honing tool 100 opposite the honing stone 180, two guide rails 120-1, 120-2 are arranged, which are offset from one another in the circumferential direction and which also Fig. 4. The guide rails are made of a wear-resistant material, for example hard metal, and are replaceably attached to the tool body. The guide rails have on their outer side, which in the assembled state is on the side facing away from the tool body 110, a substantially cylindrically curved guide surface 122-1 or 122-2, which lies radially outside the circumference of the tool body and serves to support the honing tool on the inner wall of the bore during honing. The guide surfaces should have a non-abrasive effect and are therefore machined in the example by fine-grain grinding, i.e. are relatively smooth. The guide surfaces are uninterrupted, i.e. the surface properties of the guide surfaces are essentially the same over the entire length and width.The guide rails have a flat surface 124-1, 124-2 on the side opposite the guide surface as well as axially extending flat surfaces 125, 126 aligned perpendicular to this flat surface, which form the side surfaces of the guide rail.

[0038] To insert the honing tool into the bore, the cutting tool body is retracted radially by 180° so that the abrasive outer surface (cutting surface) is retracted relative to the guide surfaces or the guide diameter. For the honing operation, the cutting tool body is then advanced radially outwards. The cutting tool body, together with the guide pads, determines the honing diameter. During honing, the cutting tool body and the guide pads are constantly in "engagement" with the inner surface of the bore, although the guide pads do not remove any material. The outer diameter of the guide pads (guide diameter) corresponds to the finished honing diameter. The cutting tool body never protrudes radially beyond the guide diameter. Only at the end of the honing operation, when the bore has reached the desired size, are the cutting edge diameter (diameter of the circular path of the cutting surface) and the guide diameter the same.

[0039] To accommodate the guide rails on the tool body, two receiving grooves 130-1, 130-2 are formed thereon, running parallel to the tool axis 112. The receiving grooves each have a receiving cross-section defined by several flat surfaces running parallel to the tool axis. Furthermore, each of the receiving grooves is defined at its axial end by an axial end surface oriented perpendicular to the tool axis (see, for example, axial end surface 136 in Fig. 3). An axial end face can serve as an axial stop for the guide rail to be accommodated in the receiving groove. If, as is often the case, an exact axial position is not important, a gap can be provided to facilitate installation and removal. The axial positioning of the guide rails usually plays a subordinate role. More important is the radial and circumferential positioning. This is ensured with high precision.

[0040] The receiving grooves are circumferentially offset by 90° relative to each other. Each receiving groove has been milled into the material of the tool body 110. Each receiving groove has an internal flat surface 132 oriented perpendicular to the radial direction, which, at its circumferential edges, transitions into flat surfaces 135 extending perpendicularly thereto. The receiving grooves thus have a rectangular cross-section over most of their length, with an axially extending web 137 remaining between the receiving grooves 130-1, 130-2.

[0041] In the area of the axial ends of the receiving grooves, the material of the tool body is milled away between them, so that the receiving grooves 130-1, 130-2 are open over a certain length on the sides facing each other. There, the guide rails are, as shown in Fig. 4, is delimited only on the radial inner sides and on the outer sides spaced apart from one another in the circumferential direction by flat surfaces 135. A radial threaded bore 152 is provided in each of these axial end sections. This bore belongs to a fixing device (explained below) with which the guide rails can be releasably secured in their receiving grooves. Those axial sections 165 in which the threaded bores 152 are located and in which the receiving grooves are laterally open to one another are also referred to here as fixing sections 165. Fig. 4 shows a section through such a fixation section.

[0042] The guide rails are secured in the receiving grooves using a fixing device 150. This device includes two clamping screws 155-1, 155-2, whose threaded portion fits into the bore 152. Each of the clamping screws has a screw head 156 with a conical underside on the side facing the threaded portion. The cone angle corresponds to the angle by which the guide rails or the receiving grooves are offset from each other in the circumferential direction, approximately 90° in the example.

[0043] To mount the guide rails 120-1, 120-2 on the tool body 110, they are first assembled as shown in Fig. 4, are inserted into their respective receiving grooves 130-1, 130-2. The guide rails are essentially fixed in the axial direction by the axial end faces 136 of the receiving grooves. To fix the guide rails in the receiving grooves, the corresponding clamping screws 155 are screwed into the threaded holes 152 in the area of the fixing sections until the conical underside of the screw head is pressed against the facing side surface of the guide rail along a more or less linear contact surface.

[0044] As in Fig. 4, two guide rails offset in the circumferential direction are pressed simultaneously into their receiving grooves using a single clamping screw 155. The clamping force acts with a circumferential component such that the guide rails are pressed against the circumferentially outer flat surfaces 126. In addition, they act with a radial component such that the guide rails are also pressed against the inner flat surfaces and are thus precisely fixed in their position. The clamping screw 156 is designed such that in this clamping configuration the outer side of the screw head is radially lower than the guide diameter defined by the guide surfaces, so that the screw head is countersunk and cannot come into contact with the inner wall of the bore.

[0045] Based on the Fig. A second embodiment of a single-strip honing tool 500 will now be described with reference to Figures 5 to 8. Since this is constructed in numerous features similar or identical to the first embodiment, the same reference numerals are used for identical or corresponding features for reasons of clarity.

[0046] A significant difference is that in the second embodiment, there is no web like the web 137 ( Fig. 3). Rather, the receiving grooves 130-1, 130-2 are open to each other on the facing sides over their entire length. A further flat surface 133 is formed on the tool body between the radially inner flat surfaces 132, with the flat surfaces 132, 133 merging into each other at longitudinal edges. The flat surface 133 forms an angle of approximately 45° with the adjacent bottom surfaces of the receiving grooves 130-1, 130-2 on both sides.

[0047] As in the first embodiment, threaded holes 152 are provided between the receiving grooves in the region of the axial ends, forming a functional component of the fixing device 150. Here, too, the fixing device 150 is designed as a clamping device. It includes a clamping element 160 separate from the tool body, whose axial length is greater than the length of the guide rails and approximately corresponds to the axial distance between the axial end faces 136 of the receiving grooves. In the example, the clamping element 160 extends beyond the front end face 136 and is flush with the end face of the tool body.

[0048] The cross-sectional area of the clamping element 160 is essentially trapezoidal, with the narrower base area having a width that essentially corresponds to the width of the flat surface 133. Adjacent to this base area at an angle of approximately 45° are flat inclined surfaces 162-1, 162-2, which are intended to be pressed against the facing lateral flat surfaces of the guide rails 120-1, 120-2. The clamping element 160 has two through holes at the axial distance from the threaded holes, which are conically countersunk on the outwardly facing outer side of the clamping element and have only a relatively short cylindrical bore section. This contour is in Fig. 8 can be clearly seen.

[0049] When assembling the honing tool, the two guide rails 120-1, 120-2 are first placed in their corresponding receiving grooves. Then, the separate clamping element 160 is placed between the guide rails and held there with one hand. In this position, the inclined side surfaces 162-1, 163-2 of the clamping element 160 press against the facing side surfaces of the guide rails, loosely securing them in the receiving grooves. Then, the two clamping screws 155-1, 155-2 are screwed in and tightened so tightly that the clamping element 160 presses with its inclined flat surfaces against the facing side surfaces of the guide rails, securing them in position in the receiving grooves.

[0050] The radial thickness of the clamping element 160 is dimensioned such that, in this clamping configuration, a small distance remains between the flat surface 133 and the base surface of the clamping element facing it, so that these flat surfaces do not abut one another, but rather the clamping screws are supported on the guide elements via the clamping element 160 and thus only indirectly on the tool body 110. This ensures secure fixation of the guide rails in the receiving grooves, even during extended use.

[0051] In the following, a third embodiment of a single-bar honing tool 900 is described with reference to the Fig. 9 to 13. In this exemplary embodiment, the two receiving grooves 930-1 and 930-2 each have a T-shaped cross-section with an outwardly open groove section, the circumferential width of which essentially corresponds to the width of the guide rails 920-1, 920-2 to be inserted. Adjoining this section is a widened foot section on the inside, so that each receiving groove has a T-shaped cross-sectional profile with an internal undercut.

[0052] The receiving grooves have an axial end surface in the direction of the connecting section 190 and are open at the opposite end, ie towards the front side or the free end of the honing tool.

[0053] Each of the guide rails 920-1, 920-2 is attached to a separate carrier 925-1, 925-2. The elongated, rail-shaped carrier has a width that is greater than the width of the guide rail. A rectangular groove for receiving a guide rail is machined into one wide side. The guide rail is fastened in the groove of the carrier, for example by soldering or gluing, and then, together with the carrier, forms a guide rail arrangement that is essentially T-shaped in cross-section. The width of the carriers essentially corresponds to the circumferential width of the wider section of the receiving grooves, so that the carriers fit into the widened sections of the receiving grooves 930-1, 930-2 with essentially no lateral play. The guide rails then protrude outwards through the narrower section of the receiving groove beyond the circumference of the tool body 110.

[0054] The fixing device for securing the guide rails in the receiving grooves engages the front side of the tool body and serves to axially secure the guide rails 920-1, 920-2 in the receiving grooves. For this purpose, a central threaded section 116 with an external thread is formed on the front end of the tool body. A retaining plate 170 belonging to the fixing device has an axial through-bore with an internal thread that fits onto the external thread of the extension. The retaining plate has a hexagonal circumferential surface and can be screwed on and off using a tool. When the retaining plate 170 is screwed on, the front openings of the receiving grooves are closed, and the inserted guide rails are axially fixed in their receiving grooves.

[0055] Numerous variations are possible within the scope of the invention. For example, it is possible to use a cylindrical feed element with a corresponding expansion cone or inclined surfaces in the area of the cutting group instead of the flat feed element.

[0056] Based on the Fig. 14 and Fig.15, a fourth embodiment of a honing tool 1400 is explained. The fixing device is based on the concept explained in connection with the third embodiment (receiving groove with undercut, guide rail arrangement with a T-shaped cross-section). However, here only a single guide rail 1420 is provided, which is arranged more or less diametrically opposite the single honing rail 180 of the single-rail honing tool. For this purpose, only a single axially extending receiving groove 1430 is machined into the tool body. The relatively wide guide rail is carried by a flat carrier which has a rectangular groove for receiving the guide rail. The receiving groove has a corresponding T-shaped cross-section with an internal undercut, wherein the receiving groove is dimensioned such that the carrier element fits into the wider section of the receiving groove with essentially no lateral play.After the guide rail assembly is axially inserted, the end-face retaining plate 1470 is screwed on to secure the guide rail. To provide a sufficiently large guide surface even with a single guide rail, the guide rail is relatively wide in the circumferential direction, so that the guide surface covers a circumferential angle range of more than 40° or even more than 50° (approximately 60° in the example).

[0057] The tool concept explained here using a few examples offers the possibility of quickly inserting or exchanging one or more guide rails made of different materials on a tool body. The tool concept can be implemented using relatively simple manufacturing resources. For example, starting from a round bar-shaped blank, it is possible to produce the tool body using only the machining processes of turning, drilling, and milling. The assembly time for the honing tools can be significantly reduced compared to previous solutions. Accordingly, tool preparation using the new tool concept is also much faster and easier for a machine operator than with conventional concepts.

[0058] The exemplary embodiments are single-stone honing tools. The invention can also be used with multi-stone honing tools with two or more (e.g., four, six, or eight) radially adjustable cutting material bodies distributed around the circumference of the tool body. In this case, guide stones arranged in pairs next to each other can each be secured by means of a common fixing device, e.g., by clamping.

Claims

[1] Honing tool (100) for machining a bore in a workpiece, comprising: a tool body (110) defining a tool axis (112); at least one cutting material body (180) that can be fed radially to the tool axis (112) in the direction of an inner surface of the bore by means of a feed system, and at least one guide bar (120-1, 120-2) arranged on the circumference of the tool body (110) for guiding the honing tool (100) in the bore, wherein the guide bar (120-1, 120-2) is replaceable, characterized by , that the tool body (110) has on its circumference for the at least one guide rail (120-1, 120-2) a receiving groove (130-1, 130-2) running parallel to the tool axis (112) with a receiving cross-section which is delimited by two or more flat surfaces (132, 135) running parallel to the tool axis (112); the receiving groove (130-1, 130-2) has an axial end surface (136) at at least one axial end, which is suitable as an axial stop for the guide strip (120-1, 120-2) to be received in the receiving groove (130-1, 130-2); a guide strip (120-1, 120-2) received in the receiving groove (130-1, 130-2) has, on its outer side facing away from the tool body (110), a guide surface (122-1, 122-2) not interrupted by a bore for contact with the inner surface of the bore and, on a side facing the tool body (110), at least two flat surfaces (124-1, 124-2, 125, 126) for surface contact with corresponding flat surfaces (132, 135) of the receiving groove (130-1, 130-2); and a fixing device (150) which can be releasably connected to the tool body is provided for fixing the guide bar (120-1, 120-2) in the receiving groove (130-1, 130-2). [2] Honing tool (100) according to claim 1, characterized bythat the honing tool (100) has a plurality of guide rails (120-1, 120-2) distributed around the circumference of the tool body (110), wherein preferably exactly two guide rails (120-1, 120-2) are provided. [3] Honing tool (100) according to claim 1 or 2, characterized by that the honing tool (100) is a single-bar honing tool (100, 500, 900) which has a single adjustable cutting material body in the form of a honing bar (180) and exactly two circumferentially offset guide bars (120-1, 120-2, 920-1, 920-2) which are configured to support the honing tool (100) on the inside of the bore on the side opposite the honing bar (180) during honing. [4] Honing tool (100) according to one of the preceding claims, characterized bythat the fixing device (150) is designed as a clamping device (150) which can be actuated by means of at least one clamping screw (155), wherein the clamping device (150) preferably comprises exactly two axially offset clamping screws (155). [5] Honing tool (100) according to one of the preceding claims, characterized by that two receiving grooves (130-1, 130-2) are formed on the circumference of the tool body (110) and are offset relative to one another in terms of their circumference, each for receiving a guide strip (120-1, 120-2), and the clamping device (150) is arranged in an intermediate region between the receiving grooves (130-1, 130-2) in such a way that at least one element of the clamping device (150) arranged in the intermediate region acts simultaneously on guide strips (120-1, 120-2) in the two laterally adjacent receiving grooves (130-1, 130-2). [6] Honing tool (100) according to claim 5, characterized bythat the receiving grooves (130-1, 130-2) are open on the mutually facing sides at least in one fixing section (165). [7] Honing tool (100 according to claim 5 or 6, characterized by that at least one threaded bore (152) for receiving a clamping screw (156) of the clamping device (150) is arranged in an intermediate region between the receiving grooves (130-1, 130-2). [8] Honing tool (100) according to claim 6 or 7, characterized by that the threaded bore (152) is arranged in the region of the fixing section (165) and a clamping screw (155) equipped with a screw head (156) is screwed into the threaded bore (152) in the clamping configuration such that the screw head (156) directly engages mutually facing flat surfaces of the guide strips (120-1, 120-2) and presses these against flat surfaces (132, 135) of the receiving grooves (130-1, 130-2). [9] Honing tool (100) according to one of claims 5 to 8, characterized byin that the clamping device (150) comprises a separate clamping element (160) which can be fastened to the tool body (110) and has at least one through-bore for passing through the threaded section of a clamping screw (155-1, 155-2), wherein the clamping element has opposite inclined surfaces (162-1, 162-2) for pressing against the mutually facing flat surfaces of the guide strips (120-1, 120-2). [10] Honing tool (100) according to one of claims 1 to 4, characterized byin that a receiving groove (930-1, 930-2) has a cross-sectional profile with an internal undercut, in particular a T-profile, wherein preferably an associated guide rail (920-1, 920-2) is fastened to a carrier (925-1, 925-2), so that a guide rail arrangement formed by the carrier (925-1, 925-2) and the guide rail (920-1, 920-2) carried thereby has a cross-sectional profile adapted to the cross-sectional profile of the receiving groove (930-1, 930-2) in such a way that the guide rail arrangement can be inserted axially into the receiving groove (930-1, 930-2) and is secured against radial falling out due to the undercut. [11] Honing tool (100) according to claim 10, characterized by that the fixing device has a holding plate (170) which can be fastened to the end face of the tool body (110) and closes a front-face opening of the receiving groove (130-1, 130-2).

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