WO2022167205A1

WO2022167205A1 - Honing bar, method for producing a honing bar and honing tool

Info

Publication number: WO2022167205A1
Application number: PCT/EP2022/050887
Authority: WO
Inventors: Jochen Brandstetter; Joachim Wiederhold
Original assignee: Kadia Produktion Gmbh + Co.
Priority date: 2021-02-05
Filing date: 2022-01-17
Publication date: 2022-08-11
Also published as: US20240042569A1; CN116917080A; EP4288247A1; DE102021201070A1

Abstract

The invention relates to a honing bar (200) for use in a honing tool for processing the inner surface of a bore, comprising a cutting layer carrier (202) which carries a cutting layer (210) on an outer side, which cutting layer has cutting grains (215) bound within a binding (213) and an abrasive work surface (220) for engaging on the inner surface of the bore. The honing bar (200) defines a longitudinal direction (L) to be oriented parallel to a bore axis. The work surface (220) extends in a width direction (B), perpendicular to the longitudinal direction, between a first lateral surface (212-1) and a second lateral surface (212-2) of the cutting layer. The work surface (220) has a generally convex macroscopic design having at least two macroscopically flat facets (230-1, 230-2, 230-3) of different orientation which transition along edges (235-1 to 235-4) extending in the longitudinal direction to an adjacent facet or a lateral surface.

Description

Honing stone, method for producing a honing stone and honing tools

FIELD OF APPLICATION AND PRIOR ART

The invention relates to a honing stone according to the preamble of claim 1, a method for producing such a honing stone and a honing tool that has at least one such honing stone.

The honing manufacturing process is often used for the quality-determining finishing of tribologically stressable inner surfaces of bores. For example, cylinder running surfaces in cylinder blocks (cylinder crankcases) or cylinder liners, bearing surfaces for shafts, e.g. in a crankshaft bearing bore, cylindrical inner surfaces in connecting rod eyes, bearing surfaces on connecting rods, gears or components for other power and work machines, such as compressors, are often processed using honing.

Honing is a machining process with geometrically undefined cutting edges, which is usually carried out with an expandable honing tool. During a honing operation in the bore, the honing tool performs a work movement consisting of two components, which leads to a characteristic surface structure of the machined inner surface. The working movement usually consists of an axially reciprocating lifting movement and a rotary movement superimposed on this. The surface structure usually shows crossed processing marks.

The honing process works with bonded cutting grain with constant surface contact between the abrasive working surfaces of the honing tool and the bore surface. The working surfaces therefore usually have a more or less strong convex-cylindrical (or also slightly conical) curvature. The cutting grains are bound in a binding system (also referred to as "binding") and together with the binding system form a cutting layer. The binding system has the task of holding the bound cutting grains in place until they are blunted by the cutting process. Then they should be released so that new, still sharp-edged cutting grains can engage with the workpiece (self-sharpening effect). For this purpose, the bond should be set back from exposed parts of the cutting grains so that there is what is known as a grain overhang. A honing tool of the type contemplated in this application has a tool body that defines a tool axis about which the honing tool rotates during honing. At least one radially advanceable honing stone is arranged on the tool body, which has a cutting surface on an outside. The cutting layer has cutting grains bonded within a bond and an abrasive working surface for engaging the inner surface of the bore.

If honing tools are equipped with fresh (newly manufactured or freshly prepared) honing stones when they are newly manufactured or as part of later maintenance or repair work, they cannot usually be used immediately with the best removal rate, but a certain running-in phase is necessary to ensure a good, to achieve a flat adaptation between the working surfaces of the honing stones and the inner surfaces of the bore to be machined. The run-in phase takes time. In addition, no good parts can usually be produced in the run-in phase, so that rejects are produced.

In order to achieve a favorable running-in behavior, a tool body is equipped with new honing stones in a known method, the honing tool assembled in this way is clamped in a cylindrical grinding machine and processed by means of cylindrical grinding with the aid of a grinding wheel while the honing tool is rotated about its tool axis. A cylindrically curved macro-shape of the abrasive working surfaces of the cutting linings is produced by the grinding process. During this grinding process, the cutting surface is given the desired roundness or cylindrical shape of the working surface, the curvature of which corresponds approximately to the curvature of the bore inner surface to be machined, so that a flat working engagement is possible. In addition, the cutting surface is given the desired straightness parallel to the tool axis. As a rule, the binding can also be set back by circular grinding, so that the work surface is easy to cut from the start.

European patent EP 3 195 978 B1 describes alternative methods for producing tools for cutting with a geometrically undefined cutting edge, the cutting grains being bound in a bond and the tool having at least one working surface. In the method, starting from a blank of the tool, the shape and/or the position of the working surface are determined by a locally limited structural change in the bond. After the structural change has been produced, the later working surface lies on the inside of the blank at the border between an edge zone whose structure has changed and the remaining structure of the cutting layer, which has not been changed. This should make it possible to process the usually sintered blank in one operation in such a way that the working surface and a downstream one are formed Sharpening the work surface is not required. Rather, the blank should be able to be used without further processing.

TASK AND SOLUTION

The object of the invention is to provide a honing stone, the use of which enables a honing tool equipped with it to produce bores with a high honing quality after just a short run-in phase. A further object is to provide a method for producing such a honing stone that can be carried out efficiently with reasonable effort and a honing tool equipped with at least one such honing stone.

To solve these problems, the invention provides a honing stone with the features of claim 1, a method for producing such a honing stone with the features of claim 8, and a honing tool with the features of claim 12. Advantageous developments are specified in the dependent claims. The wording of all claims is incorporated into the description by reference.

A honing stick according to the invention is intended to be inserted into a honing tool and to be used in the honing tool for machining the inner surface of a bore. The honing stone has a cutting layer carrier, which carries a cutting layer on an outer side, which has cutting grains bound within a bond and an abrasive working surface for engaging on the inner surface of the bore. The cutting layer contains a large number of cutting grains, which are usually distributed homogeneously within the bond.

The bond can be a metallic bond or a vitrified bond, for example. Depending on the intended application of the honing stone, the cutting grains can be, for example, diamond grains or grains of cubic boron nitride, optionally also cutting grains of silicon carbide (SiC) or corundum (aluminum oxide). Typical mean particle sizes can be, for example, in the range from 5 μm to 251 μm, in particular in the range from 10 μm to 126 μm.

The honing stick defines a longitudinal direction which, when the honing tool is assembled ready for operation, is aligned essentially parallel to the tool axis and to the bore axis of the machined bore during the honing operation. The width direction runs perpendicular to the longitudinal direction, which in the fully assembled state is essentially perpendicular to the tool axis runs. The working surface, which is located on the side of the cutting surface facing the inner wall of the bore when the honing tool equipped with the honing stone is used as intended, extends in the width direction between a first side surface and a second side surface of the cutting surface or a first and a second side edge. The side edges are the linear areas where the work surface merges into the side surfaces. When the honing stone built into the honing tool is used as intended, one of the side edges precedes the other side edge as the honing tool rotates, ie the side edges are offset relative to one another in the circumferential direction of the bore.

According to one formulation of the invention, the working surface has a generally convex macroscopic configuration in the sense that a central region between the side surfaces or side edges projects outwards, i.e. away from the cutting layer carrier, with respect to a common plane spanned by the side edges. The macroscopic shape of the work surface is characterized by at least two macroscopically planar facets of different orientation, which merge into an adjacent facet along edges running in the longitudinal direction or into a side surface at one side edge. Adjacent facets form an interior angle of less than 180° at the included edge. For example, the interior angle may be in the range of 150° to 179°.

It has been shown that such honing sticks provide a sufficiently good honing quality very quickly after the start of the running-in phase, since the macroscopic shape of the working surface adapts very quickly to the curved shape of the inner surface of the bore due to the initially faceted macro shape. At present, this surprising effect is understood in such a way that the working surface, which is still faceted at the beginning, comes into contact with the bore inner surface only along one or more longitudinal edges when the honing stone is advanced radially. Due to the more or less linear contact, there is high surface pressure in the area of the edges and correspondingly high wear on the cutting surface, so that the macro shape of the working surface, starting from the edges in both circumferential directions, adapts very quickly to the curved shape of the inner surface of the bore. As a result, complete surface contact between the work surface and the inner surface of the hole is quickly established over the entire width between the side edges.

These advantages in running-in behavior can be achieved in a relatively simple and correspondingly cost-effective manner, since the production of macroscopically planar facets on a cutting layer is simpler and cheaper to produce in terms of production technology than, for example, the production of cylindrically curved work surfaces during cylindrical grinding.

Another advantage is that the diameter range around a nominal diameter for which a honing stone with a faceted working surface can be used is comparatively larger than the diameter range that can be easily covered by a working surface that has already been cylindrically curved. Honing stones according to the claimed invention are thus characterized by being relatively easy and inexpensive to manufacture, quick adaptation to the bore surface to be machined and a certain tolerance with regard to the bore diameter.

It can be sufficient if the work surface has only exactly two facets between the side surfaces or the side edges, so that the work surface assumes a roof shape. Preferred embodiments have more than two facets, such as three, four, five, or six facets. As a result, a continuously curved surface can be better approximated.

It has turned out to be particularly advantageous if the work surface has exactly three facets. This number represents a good compromise between good adaptability to the inside diameter of the bore on the one hand and simple production on the other.

In some embodiments, the facets have substantially equal widths. A "substantially equal width" is given when the widths of the facets to be compared do not differ by more than ± 20%. This results in a particularly even distribution of the contact pressures in the edge areas and a correspondingly even adjustment during the running-in phase.

According to one development, the facets are dimensioned such that the side edges and the at least one edge between facets lie on a common cylindrical surface that has a radius of curvature that essentially corresponds to a nominal radius of the borehole to be machined later. In this way it can be achieved that right at the beginning both the edges that form on the side edges between the side surface and the side facet and the edges in between (one or more) rest more or less simultaneously under similar pressing conditions on the inner wall of the bore, which causes the change in shape is distributed favorably over all edges right from the start in the running-in phase. In preferred exemplary embodiments, the bond is set back on the working surface in relation to exposed parts of the cutting grains, so that there is a grain protrusion. The facets are therefore ready to cut right from the start, even during the running-in phase.

In a method for producing such a honing stone, a honing stone blank is first provided, which has a cutting surface carrier which carries a cutting surface on an outside, which has cutting grains bound within a bond. An abrasive working surface intended for engagement with the inner surface of the bore is then produced on the cutting layer. As mentioned above, viewed in the width direction, this extends between a first and a second side edge or between the side surfaces of the cutting surface. The work surface is created to have a generally convex shape with at least two facets merging along longitudinal edges to an adjacent facet or face.

The facets could already be produced during the production of the cutting layer, for example during the sintering of a sintered cutting layer by appropriate shaping of a mold.

However, the facets are preferably produced by local material removal starting from a raw state of the cutting layer. In most cases, blanks are used in which a cutting layer of constant thickness is applied to a flat outer side of the cutting layer carrier, so that the honing stone blank has a rectangular cross-sectional shape overall before the facets are produced on the cutting layer by locally unequal material removal.

In preferred embodiments, the facets on the cutting surface of the honing stone blank are produced by surface grinding, in particular face grinding. Face grinding results in a particularly even wear of the face grinding tool, so that large quantities can be processed without having to dress the grinding tool again. A cup wheel, for example, can be used as the grinding tool.

In many cases, a surface grinding tool with diamond cutting grains, which can be bonded in a metallic matrix, for example, is used to produce the facets. Such grinding tools are characterized, among other things, by a long service life and can process many different types of cutting layers in a material-removing manner. Preferably, the manufacture of the honing stone also includes resetting the bond on the work surface at the facets. The creation of the work surface is preferably achieved in two successive stages. In a first step, essentially planar facets without grain overhang are produced, before the bond on the facets is reset in a second step in relation to the cutting grains in a reset operation.

For the resetting operation, a face grinding tool with a cutting surface can be used, the cutting grains of which are harder than the bond of the cutting surface of the honing stone, but cannot cut the cutting grains of the cutting surface of the honing stone.

The invention also relates to a honing tool which has at least one honing stone of the type described here.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and aspects of the invention result from the claims and from the description of exemplary embodiments of the invention, which are explained below with reference to the figures.

1 shows a longitudinal section through an embodiment of a single-stick honing tool with an inserted honing stick before the running-in phase;

2 shows a schematic cross-section through the cutting area of the honing tool and through the honing stone;

3 shows a schematic representation, not true to scale, of a cross section through the honing stone, taken perpendicularly to the longitudinal direction of the honing stone;

4A, 4B, 4C show different phases of the manufacture of the honing stone.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

In the following description of exemplary embodiments, identical or similar features are denoted by the same reference symbols in all examples shown for reasons of clarity. 1 shows a longitudinal section through an embodiment of a honing tool 100 parallel to the tool axis (axis of rotation) 112 of the honing tool. The honing tool is designed as a single-bar honing tool, ie it has only a single honing bar 200. Other embodiments have a plurality of honing bars distributed over the circumference, for example two, three or four (multi-bar honing tool). 2 shows a schematic cross section through the cutting area with the honing stone.

The honing tool 100 has a tool body 110 made of steel or hard metal in the form of a tube that is open on both sides and has a relatively large wall thickness. An end section of the tool body is inserted into a cylindrical receiving opening of a tool shank 120 in a rotationally fixed manner and is fixed there with the aid of a retaining screw 122 . The tool shank 120 is used to couple the honing tool to the honing spindle of a machine tool. Tool shank and tool body can also be detachably or non-detachably connected to one another in other ways, for example by clamping, by soldering or the like.

The cutting area of the honing tool is located in a free end section of the tool body opposite the tool shank. The bore has a nominal diameter D, which can be, for example, in the range from 10 mm to 40 mm, but it can also be larger or smaller if necessary.

In the cutting area, the tool body 110 has a rectangular honing stone receiving opening 140 that extends outwards from the interior of the tool body and in which the honing stone 200 is accommodated with a precise fit and in a radially displaceable manner when the honing tool is assembled.

In its longitudinal direction L running parallel to the tool axis 112 , the honing stone 200 has a length that is greater than the width measured in the width direction B, which runs perpendicular to the longitudinal direction L and to the radial direction R. It is also possible for the axial length of a hollow strip to be shorter than the width measured in the circumferential or widthwise direction.

On the side opposite the honing stone receiving opening 140, two guide strips 180, 181 made of hard metal, sintered metal or another hard material, for example ceramic, are attached to the tool body and are circumferentially offset by approximately 90°. These are designed to support themselves with their smoothly polished, curved outer surfaces on the inner wall of the bore to be honed. The guide rails can have a coating made of diamond, for example, which forms a wear-resistant outer surface.

The overall plate-shaped honing stone 200 has a plate-shaped cutting layer carrier 202 made of steel, often also referred to as a supporting strip, on whose flat, radial outside 204 a cutting layer 210 is applied, which holds the cutting material grains 215 bound in a bond 213 . The cutting layer of the example has diamond cutting grains bound in a metallic bond (e.g. made of a bronze alloy). In the example, the cutting layer 210 is sintered onto the cutting layer carrier 202, but in other embodiments it can also be glued or soldered on or fastened to the cutting layer carrier by rivets or screws. A honing stone can also be formed by a one-piece sintered body. On the radially outer side of the cutting pad 210 is an abrasive working surface 220 intended to engage the inner surface of the bore.

The radial inner side of cutting pad carrier 202 has a flat inclined surface 216 which interacts with a complementary flat inclined surface on the lower end of an infeed rod 130 guided in the tool body in the manner of a wedge drive in such a way that honing stone 200 is pressed radially outwards within honing stone receiving opening 140 when the The feed rod is pushed in the direction of the cutting area of the honing tool by the feed drive housed in the honing machine.

During honing, the honing tool 100 with the abrasive working surface 220 should be in constant surface contact with the inner surface 192 of the bore 195 . In the case of a well-run-in honing tool, the abrasive working surface is therefore essentially cylindrically curved and has a radius of curvature which essentially corresponds to the inner radius of the machined bore.

However, this is not yet the case with the honing tool 100 . It is a honing tool equipped with a newly manufactured or reconditioned honing stone 200 that has not yet undergone a honing operation. The honing tool can therefore be a new tool or a used honing tool that is fitted with a new or fresh honing stone 200 .

The honing stick 200 is characterized by special features that enable the honing tool to produce good parts with high honing quality on the inner surface of the bore after a very short running-in phase. For illustration, Fig. 3 shows a schematic, not true-to-scale representation of a cross section perpendicular to the longitudinal direction L of the honing stone through the honing stone 200. The cutting coating 210 is firmly applied to the flat, radial outside 204 of the cutting coating carrier 202 either directly or with at least one intermediate layer in between. The cutting layer has a (mean) thickness DS, which can be of the order of 1 mm, for example. In the width direction B, the cutting layer is delimited by side faces 212-1, 212-2, which in the example shown are flush with the side faces of the plate-shaped cutting layer carrier 202, so that the honing stone has a plate shape overall.

There are also variants in which the cutting pad carrier is wider than the cutting pad. For example, a narrower groove can be milled or produced in some other way in the middle or off-center of the wide outside of the cutting pad carrier, in which the cutting pad is accommodated. Then there are supporting edges made of the material of the cutting layer carrier on both sides of the cutting layer.

The work surface 220 has a generally convex macroscopic shape such that the central portion of the work surface bulges outward in the radial direction R relative to the edge portions at the side surfaces. However, the convex shape is not rounded but faceted. Specifically, the work surface 220 has three macroscopically planar facets 230-1, 230-2, 230-3, which merge along edges running in the longitudinal direction L (longitudinal edges) to an adjacent facet or a side edge or a side surface. The first facet 230-1 adjoining the side surface 212-1 that can be seen on the left encloses an angle of more than 90° with this side surface at the side edge and forms a first edge 235-1 with it. A second facet 230-2, which runs parallel to the flat outside 204 of the cutting pad carrier 202, encloses an interior angle IW of less than 180° with the first facet 230-1 and together with this forms a second edge 235-2 at the transition. On the side that can be seen on the right, there is a third facet 230-3, which transitions to the second facet in the area of a third edge 235-3 and encloses an interior angle of less than 180° with it. The third facet merges into the right side surface 212-2 or the right side edge along a fourth edge 235-4.

On the faceted surfaces, the cutting grains protrude beyond the level of the bond, so there is a grain protrusion, so that the freshly prepared, faceted work surface is easy to cut, especially in the area of the longitudinal edges 235-1 etc.

The proportions are not shown to scale. Depending on the nominal diameter for which the honing stone is optimized, as well as depending on the number of Facets, the interior angles IW can be, for example, in the order of magnitude between 170° and 179°, optionally also above or below. The widths of the facets measured in width direction B are approximately the same size, they preferably differ by no more than ±20%. If there is an odd number of facets, a central facet (here the second facet 230-2) is preferably provided, the facet surface of which runs parallel to the outer surface 204 of the cutting pad carrier. The second facet can be formed by the original surface of the cutting layer initially applied with a uniform layer thickness DS, or it can already be machined by being set back in parallel.

The number of facets and the widths of the facets are preferably coordinated in such a way that the edges consisting of cutting material essentially lie on a common cylindrical surface Z (shown with a dashed line) whose radius of curvature corresponds to the nominal radius of the bore to be machined. This ensures that the fresh honing stone rests against the inner wall of the bore on all edges (longitudinal edges) when it is first fed in the direction of the inner wall of the bore. In contrast, in the areas between the longitudinal edges, viewed in the radial direction, there is in each case a more or less large gap between the facet and the inner wall of the bore.

The faceted geometry of the abrasive working surface 220 enables short run-in times before the honing stone is in full, large-area engagement with the inner wall of the bore on its working surface. At the beginning of the running-in phase, only the longitudinal edges are in contact with the inner wall of the bore. Due to the resulting high surface pressure, the wear on the cutting surface is greatest in the edge areas, so that the edges quickly round off and the rounded areas of adjacent edges quickly approach one another until the facets disappear and a consistently cylindrically curved working surface is created. Thus, honing tools that are equipped with such honing stones can work productively after a very short time, so that there is little or no scrap on the machined workpiece.

Fresh honing stones of the type described here can be produced in a relatively simple and cost-effective manufacturing process with a geometry that can be specified precisely. An exemplary manufacturing process is explained with reference to FIGS. 4A to 4C.

First, a honing stone blank is produced, in which a cutting coating 220 with a constant layer thickness is applied to the flat outside of a plate-shaped cutting coating carrier 202, for example by sintering. Then starting from the more or less flat outer surface of the cutting layer facets attached, which lead to the desired faceted macro shape. In the example, a surface grinding method is used for this purpose using a cup wheel 300, which is driven to rotate about an axis of rotation 302 and is fitted with diamond cutting means. The face 305 oriented perpendicularly to the axis of rotation is in grinding engagement with the cutting surface (face grinding). In the case of the third cut described here, one of the side facets (first or third facet) is first produced, then the grinding tool and the honing stone are tilted relative to one another in such a way that the other facet surface (third or first facet) is produced by face grinding. Depending on the pre-machining quality, the middle facet (second facet) can remain unmachined or it can also be reworked by surface grinding, so that all facets essentially have the same surface quality.

In the example, the cutting grains of the surface grinding tool 300 are harder than the cutting grains 215 in the cutting layer of the honing stone, so that cutting grains of the cutting layer are at least partially removed and a macroscopically flat grinding surface with partially cut cutting grains is created.

In a second process step, the bond is then mechanically set back in relation to the cutting grains (cf. FIG. 4C). The honing stone remains in the same clamping position, so it does not have to be re-clamped. Instead of the diamond cup wheel, however, a surface grinding tool with silicon carbide abrasive is used, which can reset the bond but leaves the harder cutting grains unharmed. The infeed of the grinding tool is selected in such a way that there is a balance between abrasion on the cutting surface of the honing stone and wear on the grinding wheel. After resetting the binding, the honing stone is ready for use.

There are numerous variants. The number of facets is not limited to three; only two facets can be provided, for example, so that the abrasive working surface initially has a roof shape. More than three facets can also be provided, for example four or five facets. This can be beneficial to achieve an even faster break-in period, but has to be traded off against a slightly longer manufacturing process. Furthermore, it is not absolutely necessary that the facets all have essentially the same width. Facets with unequal widths can also be created. As a rule, however, the faceted surface is essentially mirror-symmetrical to a plane of symmetry that lies between the broad sides of the honing stone in the width direction. The concept of the invention can be used with different types of cutting coatings, for example cutting coatings with a metallic bond or ceramic bond or with a synthetic resin bond.

Claims

patent claims

1. Honing stick (200) for use in a honing tool (100) for machining the inner surface (192) of a bore (195), comprising: a cutting pad carrier (202) which carries a cutting pad (210) on an outside, which is inside a binding (213) has bonded cutting grains (215) and an abrasive working surface (220) for engaging the inner surface (192) of the bore (195), the honing stone (200) defining a longitudinal direction (L) to be aligned parallel to a bore axis and the working surface (220) extends in a width direction (B) perpendicular to the longitudinal direction between a first side surface (212-1) and a second side surface (212-2) of the cutting layer, characterized in that the working surface (220) has a generally convex macroscopic shape with at least two macroscopically planar facets (230-1, 230-2, 230-3) of different orientation adjacent to one along longitudinal edges (235-1 to 235-4). th facet or a side face.

2. Honing stone according to claim 1, characterized in that adjacent facets at the included edge form an interior angle of less than 180°, the interior angle preferably being in the range of 170° to 179°.

3. Honing stone according to claim 1 or 2, characterized in that the working surface (220) has exactly three facets (230-1, 230-2, 230-3).

4. Honing stone according to one of the preceding claims, characterized in that the facets (230-1, 230-2, 230-3) have substantially the same widths.

5. Honing stone according to one of the preceding claims, characterized in that the facets (230-1, 230-2, 230-3) are dimensioned such that the edges (235-1, 235-4) on the side surfaces and the at least an edge (235-2, 235-3) between facets (230-1, 230-2, 230-3) lying on a common cylindrical surface (Z) having a radius of curvature substantially equal to a nominal radius of the bore (195) is equivalent to.

6. Honing stone according to one of the preceding claims, characterized in that on the working surface (220) the bond (213) is set back in relation to exposed parts of the cutting grains (215), so that there is a grain protrusion.

7. Honing stone according to one of the preceding claims, characterized in that the cutting surface (210) contains diamond cutting grains (215) in a metallic bond (213).

8. A method for producing a honing stone (200) for use in a honing tool (100) for machining the inner surface (192) of a bore (195), comprising the following steps:

Providing a honing stone blank with a cutting layer carrier (202) which carries a cutting layer (210) on an outer side (204) which has cutting grains (215) bound within a bond (213);

Generating an abrasive working surface (220) on the cutting surface (210) intended for engagement on the inner surface of the bore, the working surface defining a longitudinal direction (L) to be aligned parallel to a bore axis and extending in a width direction (B) perpendicular to the longitudinal direction between a first side surface (212-1) and a second side surface (212-2) of the cutting pad (210), characterized in that the working surface (220) is created such that it has a generally convex shape with at least two facets (230-1, 230-2, 230-3) merging along longitudinal edges (235-1 to 235-4) to an adjacent facet or face.

9. The method as claimed in claim 8, characterized in that some or all of the facets (230-1, 230-2, 230-3) are produced by removing material from a raw state of the cutting layer (210).

10. The method according to claim 9, characterized in that the facets (230-1, 230-2, 230-3) on the cutting surface (210) of the honing stone blank are produced by surface grinding, preferably with a surface grinding tool diamond cutting grains is used.

11. The method according to claim 8, 9 or 10, characterized by resetting the binding (213) on the facets (230-1, 230-2, 230-3) of the working surface (220), wherein preferably when generating the facets in in a first step, essentially flat facets without grain protrusion are produced and then in a second step the bond (213) on the facets is reset in a reset operation, with a surface grinding tool with a cutting surface preferably being used in the reset operation, - 16 - whose cutting grains are harder than the bond of the cutting layer of the honing stone, but cannot cut the cutting grains of the cutting layer of the honing stone.

A honing tool (100) for machining the inner surface (192) of a bore (195), comprising: a tool body (110) defining a tool axis (112) about which the honing tool (100) rotates during honing; at least one honing stone (200) arranged on the tool body, which can be advanced radially to the tool axis (112) and has a cutting surface (210) on an outside, the cutting grains (215) bound within a bond (213) and an abrasive working surface (220) for engagement on the inner surface (192) of the bore (195), characterized in that the honing stone (200) is designed according to one of Claims 1 to 7.