DE102019201465A1 - Honing tool and finishing process using the honing tool - Google Patents

Abstract

A honing tool (100) for machining an inner surface of a bore in a workpiece using at least one honing operation comprises a tool body (110) which defines a tool axis (112); a first cutting group (160-1) attached to the tool body with a plurality of radially deliverable first carriers (150-1) which can be advanced radially to the tool axis (112) by means of an assigned first cutting group infeed system (170-1), each first carrier on its radial outer side covers a circumferential angular range of at least 20 ° and on the outer side (154) carries a single first cutting material body wide in the circumferential direction or several narrow first cutting material bodies (140-1) which are arranged at a mutual distance from one another; and a second cutting group (160-2) which is attached to the tool body and has a plurality of radially adjustable second carriers (150-2) which are radially to the first carriers (150-1) by means of an associated second cutting group infeed system (170-2) Tool axis (112) can be advanced, with each second carrier (150-2) carrying a single narrow second cutting material body (140-1, 140-2) on its radial outer side (154). All cutting material bodies (140-1, 140-2) of the first and second cutting groups are arranged in an axially short cutting area (130) which has a length measured in the axial direction that is significantly smaller than an effective outer diameter of the cutting groups when the cutting material bodies are completely retracted .

Description

APPLICATION AREA AND PRIOR ART

The invention relates to a honing tool according to the preamble of claim 1 and a fine machining method according to the preamble of claim 12. A preferred area of application is the fine machining of cylinder liners in the manufacture of cylinder blocks or cylinder liners for reciprocating piston machines.

The cylinder running surfaces in cylinder blocks (cylinder crankcases) or cylinder liners of internal combustion engines or other reciprocating piston machines are exposed to severe tribological stress during operation. Therefore, when manufacturing cylinder blocks or cylinder liners, it is important to machine these cylinder liners in such a way that sufficient lubrication is guaranteed by a lubricant film under all operating conditions and that the frictional resistance between parts moving relative to one another is kept as low as possible.

The quality-determining finishing of such tribologically stressable inner surfaces is generally carried out using suitable honing processes, which typically involve several successive honing operations. Honing is a cutting process with geometrically undefined cutting edges. In the case of a honing operation, an expandable honing tool is moved up and down or back and forth within the bore to be machined to produce a lifting movement in the axial direction of the bore, and is simultaneously rotated to produce a rotary movement superimposed on the lifting movement. The cutting material bodies attached to the honing tool are pressed against the inner surface to be machined via a feed system with a feed force acting radially to the tool axis. During honing, a cross-cut pattern typical of honing is created on the inner surface with intersecting machining marks, which are also referred to as "honing grooves".

With increasing demands on the economy and environmental friendliness of engines, the optimization of the tribological system piston / piston rings / cylinder surface is of particular importance in order to achieve low friction, low wear and low oil consumption. The macroscopic shape (macro shape) of the bores and the surface structure are of particular importance.

In some fine machining processes, a bore shape that differs from the shape of a circular cylinder is created by means of fine boring and / or honing. Such bore shapes are generally asymmetrical in the axial direction and / or in the circumferential direction, because the deformations of the cylinder block are also generally not symmetrical. In the operating state, the ideal circular cylinder shape should usually result, so that the piston ring assembly can seal well over the entire circumference of the bore.

The DE 10 2013 204 714 A1 discloses honing tools which are suitable, inter alia, for machining, rotationally symmetrical bores, which have bore sections of different diameters and / or shapes. For example, rotationally symmetrical bores with bottle shape, cone shape or barrel shape can be processed and / or generated. The honing tool has an annular expandable cutting group with a plurality of cutting material bodies distributed around the circumference of the tool body, the axial length of which in the axial direction (parallel to the tool axis) is smaller than an effective outer diameter of the cutting group when the cutting material bodies are completely retracted. The cutting group has a plurality of radially adjustable supports which carry cutting material bodies in the form of honing segments on their radial outer sides, each of which covers a circumferential angle range which is greater than the axial length of the cutting group.

Because of the relatively short axial length of the cutting group, such honing tools are particularly well suited for generating an axial contour and / or for tracking an existing axial contour of the bore. In addition, small axial lengths of the cutting group can be advantageous in order to generate a sufficient surface pressure for the machining. The fact that the cutting group has a plurality of radially adjustable supports, each of which covers a circumferential angle range that is greater than the axial length of the cutting group, means that, for example, transverse bores in the wall of a cylinder raceway can be bridged in the circumferential direction during honing that, despite the axially short cutting material body, there is no risk of uneven machining in the area of cross bores. When using such honing tools, it is also possible to work with a very small honing overflow at the axial ends of a bore without problems with uneven cutting body wear.

The DE 10 2014 212 941 A1 the applicant shows similar honing tools with a relatively short annular cutting group in the axial direction, in which a large proportion of the circumference is covered with cutting means. In addition, a guide group with adjustable guide rails is provided. The annular cutting group has a relative circumferential direction wide beams that can be fed together radially via an infeed system. In some exemplary embodiments, the outer sides of the carriers are covered with a shell-shaped full covering (honing segment). It may also be the case that the outer sides each carry cutting material bodies with axial longitudinal grooves, so that the radially outer cutting surfaces are interrupted several times in the circumferential direction. Variants are also described in which a plurality of relatively narrow honing stones are attached to the outside of the rigid supports, which are curved in the shape of a circular arc in the circumferential direction and have a circumferential spacing from one another, so that groove-like spaces are formed between the honing stones. The grooves or spaces allow efficient supply and removal of cooling lubricant and removal of abrasion.

It has been observed that in certain cases when machining non-cylindrical bores (e.g. rotationally symmetrical bores with bottle shape, cone shape or barrel shape) locally different surface structures can be created due to different cutting depths. These can cause technical disadvantages. If the local roughness is too high, e.g. Oil consumption and blow-by are increased. If too little material removal is generated locally, the risk of seizure in the operation of an internal combustion engine may increase due to the insufficient elimination of material damage from upstream processing stages. Close to the axial ends of a hole, the micrograph can deviate from the micrograph in the rest of the hole.

TASK AND SOLUTION

It is an object of the present invention to provide a honing tool of the generic type and a finishing process which can be carried out with it, which allow bores of different shapes to be machined in such a way that the machined bore surfaces have a well-defined surface structure over the entire bore length.

To achieve this object, the invention provides a honing tool with the features of claim 1. Furthermore, a finishing process with the features of claim 12 is provided. Advantageous further developments are specified in the dependent claims. The wording of all claims is incorporated by reference into the content of the description.

The honing tool has a tool body that defines a tool axis. Directions parallel to the tool axis are referred to as the “axial direction” or “axial direction”. Two independently adjustable cutting groups are attached to the tool body, namely a first cutting group and a second cutting group. The first cutting group has a plurality of first carriers which can be advanced radially to the tool axis by means of an assigned first infeed system. The first carriers each cover a relatively wide circumferential angle range of at least 20 ° on their radial outside.

The circumferential angle range covered by a first carrier can e.g. 25 ° or more or 30 ° or more. The circumferential angle range is preferably at most 120 ° or at most 90 °.

The number of first carriers can vary from embodiment to embodiment, e.g. depending on their circumferential width. Preferably three or more first carriers are provided, e.g. three, four, five or six first carriers, possibly only two first carriers.

On their relatively wide radial outer sides, the first carriers either carry a single circumferentially wide first cutting material body, e.g. in the manner of a bowl-shaped full covering with a continuous (uninterrupted) or cutting surface interrupted by grooves, or a plurality of narrow first cutting material bodies which are arranged at a mutual distance (in the circumferential direction) from one another. Most of the first carriers have the same type of first cutting surface (full surface, possibly with grooves or strip group with several narrow first cutting material bodies), but this is not mandatory.

The second cutting group, which is likewise attached to the tool body, has a plurality of second carriers which can be advanced radially to the tool axis by means of an assigned second infeed system. Each of the second carriers carries only a single narrow second cutting material body on its radial outside.

The term “cutting material body” describes the abrasive elements of the honing tools. In honing tools, a cutting material body, which can also be called a cutting surface, essentially consists of irregularly shaped cutting grains of different shapes and sizes, which are bound within a binding system. By selecting the type of cutting surface, a honing tool can be adapted particularly precisely to the desired machining task. Cutting grains can be, for example, diamond grains or cubic boron nitride (CBN) grains. Cutting grains can also consist of corundum and / or other types of ceramic materials, such as SiC. The binding can for example consist of a ceramic material or made of synthetic resin. Metallic binding systems, for example galvanically produced bonds or sintered bonds, are also possible, and possibly also solder bonds.

The term “narrow” in connection with cutting material bodies means that the width of the (narrow) cutting material bodies in the circumferential direction is significantly smaller than a length measured in the axial direction. An aspect ratio between (axial) length and (measured in the circumferential direction) width can be, for example, in the range from 5 or more, in particular in the range from 8 to 25. Narrow cutting material bodies are often also referred to as cutting bars or honing bars. Expressed in absolute values, the narrow first cutting material bodies can e.g. Have circumferential widths in the range from 1.5 mm to 5 mm, possibly also above or below.

A first cutting material body, which is relatively wide in the circumferential direction, which e.g. can be designed in the manner of a bowl-shaped full covering, preferably has a significantly smaller aspect ratio, e.g. can be in the range of 3 or less, possibly also 1 or less, so that the width in the circumferential direction can be greater than the axial length.

The optimal dimensions of the cutting material body are usually dependent on the effective diameter of the honing tool or the diameter of the bore to be machined.

The cutting material bodies of the first cutting group and the second cutting group are arranged in an axially relatively short cutting area. The cutting area has a length measured in the axial direction, which is considerably smaller than an effective outer diameter of the cutting groups when the cutting material bodies are completely retracted. “Much smaller” here means that the axial length or extension of the cutting area is at most 80% of the effective outer diameter of the cutting groups. In other words, “significantly smaller” means: at least 20% smaller. The axial length can e.g. be less than half the effective outer diameter. The first cutting material bodies and the second cutting material bodies are thus arranged in such a way that they all lie completely within a cutting region that is relatively short in the axial direction. Because of the relatively short axial length of the cutting area, honing tools of this type are particularly well suited for producing bore shapes with an axial contour, that is to say with different diameters in the axial direction. Alternatively or additionally, they can also be used to track such an existing axial contour of the bore.

The axial length or extension of the cutting area can e.g. are less than 40% of the effective outer diameter of the cutting groups and / or less than 20% of the bore length of the bore.

Investigations by the inventors have shown that the special division of cutting material bodies on the first and second carriers offers particular advantages. Each of the first carriers covers a certain, relatively wide circumferential area with the first cutting material bodies attached to it (e.g. a wide solid covering or several narrow, strip-shaped cutting material bodies per carrier). It has been shown that when honing using the first cutting group, i.a. particularly good roundness values of the bore produced can be achieved. In the variants with several narrow cutting material bodies per first carrier, the large number of first cutting material bodies, which are simultaneously in engagement with the inner wall of the bore, results in good service lives even in the case of strongly material-removing shapes. In the variants with relatively wide first cutting material bodies, a relatively efficient material removal with little wear is also possible.

According to the inventors' findings, the second cutting group with individual, relatively narrow cutting material bodies offers other advantages. It was found that individual, individually adjustable second cutting material bodies, which can be adjusted in different radial directions, tend to lie more firmly (better, more even surface contact) on an existing surface than first cutting material bodies, which only work together or in groups per second carrier in a common radial direction against the inner wall of the bore can be pressed. This enables particularly high surface qualities to be achieved.

The total cutting area of the second cutting group can be less than the total cutting area of the first cutting group. This can be particularly advantageous if only relatively little substantial material removal is to be achieved with the second cutting group, e.g. when plateau honing or smoothing a surface previously worked with coarser cutting agent.

The first and the second cutting group can be adapted to one another and to the honing process with regard to the type and dimensioning of the cutting material bodies in such a way that they wear out more or less equally or equally quickly in the intended honing process. Among other things, this is favorable for an economical new equipment.

In many embodiments, the number of second cutting material bodies is greater than the number first cutting material body, among other things in order to obtain comparable service life and coverage.

In the variants with a plurality of narrow cutting material bodies per first carrier, more than two first cutting material bodies are preferably attached to the radial outside of a first carrier, for example three, four, five, six, seven or more first cutting material bodies. Experience has shown that between three and seven first cutting material bodies per carrier are often advantageous.

In some embodiments of these variants, the mutual distance between immediately adjacent first cutting material bodies is of the order of magnitude of the circumferential width of the cutting material bodies or less. If the mutual distance is smaller than the circumferential width of the first cutting material body, viewed in the circumferential direction, a relatively high proportion of the area of the abrasive material of the first cutting material body can be ensured, so that high material removal with low wear is possible. Material chips that have been removed can be removed well by means of cooling lubricant through the channels lying between the first cutting material bodies, so that the risk of clogging of the abrasive outer surfaces of the cutting material bodies can be kept low.

The outer cutting surfaces of the first cutting material bodies carried by a first carrier preferably cover a total circumferential angle range which corresponds to at least 30% or at least 50% of the circumferential width of the carrier, so that a relatively large total cutting surface is used in the first cutting group when viewed in the circumferential direction and thus a relatively high stock removal rate can be achieved with a long service life.

It may be sufficient if the second cutting group has a relatively small number of narrow second cutting material bodies that can be set in different radial directions, for example four, six, eight or ten second cutting material bodies. The second cutting material bodies can be distributed symmetrically or asymmetrically over the circumference of the honing tool.

In some embodiments, the first carrier and second carrier and the associated cutting material bodies are arranged alternately on the tool body in the circumferential direction. The distribution in the circumferential direction can vary. At least one second carrier is preferably arranged between first carriers which are adjacent in the circumferential direction. It may be that exactly a second carrier with an associated second cutting material body is arranged between a pair of immediately adjacent first carriers. At another point on the circumference and / or in another embodiment, it may be the case that two or more second carriers are arranged between immediately adjacent first carriers, so that there are second carriers which are immediately adjacent in the circumferential direction. In this way, the circumferential density of the second carrier and / or the second cutting material body carried by it can be optimized for each application.

A uniform distribution of the first and second carriers, viewed in the circumferential direction, is possible. In many embodiments, however, the first carriers and the second carriers are arranged unevenly distributed in the circumferential direction, in particular such that intermediate circumferential angles vary.

The arrangement is preferably such that pairs of the same type of carrier and cutting material body are arranged at diametrically opposite positions on the circumference, so that, due to this symmetry, there are no design-related resulting transverse forces which lead to an undesired deflection of the honing tool during machining can.

The first cutting material body and the second cutting material body can have the same length in the axial direction. If, moreover, all are arranged in the same axial section, the axial length of the cutting region results from the axial length of the first and second cutting material bodies. The first and second cutting material bodies can also be slightly axially offset from one another, so that the axial length of the cutting region can become somewhat larger than the axial length of the longest of the cutting material bodies.

In one embodiment, the first cutting material bodies are shorter in the axial direction than the second cutting material bodies. The axial length of the first cutting material body can be, for example, less than 80% or less than 70% of the axial length of the second cutting material body, but generally not less than 50% of this length. In this way it can be achieved that the first cutting group in the delivered state, that is to say when machining the inner bore surface, acts in an effective first cutting area that is shorter than the cutting area of the honing tool. With this e.g. Bore sections with a larger diameter change in the axial direction (small radii) can be machined particularly well. It is also possible that second cutting material bodies are shorter in the axial direction than first cutting material bodies.

In some embodiments, the second cutting material bodies are related to the Tool body resiliently supported. The ability of the second cutting material bodies to follow the contour without contact pressure peaks can be improved by the elastically flexible bearing, which can have a positive effect on the quality of the surfaces that can be achieved. The elastic compliance can be achieved in different ways. For example, it is possible to work within the second infeed system up to the carrier without any design-related flexibility and to provide an elastic flexibility between the carrier and the worn cutting material body. This can be achieved, for example, by arranging an elastically flexible intermediate layer in an intermediate space between a cutting material body and the carrier carrying the cutting material body, which intermediate layer can be formed, for example, by a layer made of an elastomer. The intermediate layer can completely fill the intermediate space in order to prevent penetration of cutting agent residues or abrasion. With regard to this sub-aspect, reference is made to the DE 10 2017 202 573 A1 referred to the applicant, which describes the implementation options for this. In this respect, the disclosure content of this document is made the content of the description by reference.

In some embodiments, the elastic flexibility is achieved in that the second carrier has an elastically flexible section with (recess material-free) recesses and spring elements formed in one piece with the carrier, close to or adjacent to a second cutting material body. In comparison to similarly possible designs with separate springs within the delivery system, such variants with monolithically integrated spring elements are characterized, among other things, by the fact that the spring force can be specified with high precision during the manufacture of the carriers. This solution is also extremely robust and durable.

In the case of variants with separate springs for the flexible storage of the second cutting material bodies and in the case of variants with the cutouts in the carrier material, it can happen that abrasion gets into the spring area and impairs the function. In some embodiments, this is prevented by filling the area between spring windings or in the recesses free of spring material with an elastically flexible elastomer material or another elastically flexible filling material. This keeps the spring effect in the long term. By selecting suitable elastically flexible filling materials, the spring characteristics, e.g. the "hardness" of the suspension can be set precisely. Some of the free spaces in the spring area can be filled. These measures can be used independently of the other features of the invention also in honing tools not according to the invention with elastic compliance in the honing tool

In some embodiments, the honing tool has a guide group with a plurality of guide strips distributed around the circumference of the tool body. These can be firmly attached to the tool body. Individual, several or all guide strips can at least partially extend into axial areas outside the cutting area. In some embodiments, the guide strips are arranged only within the cutting area. This can ensure that the guide strips do not come into unwanted contact with the inner surface of the bore even in bore sections with an axially widely varying diameter. One, several or all guide rails can be arranged directly next to a second carrier, so that the adjacent second carriers are protected by the immediately adjacent guide rail.

A further contribution to achieving high surface qualities is achieved in some embodiments in that the honing tool has an integrated multi-axis joint for coupling the tool body to a connecting piece with limited mobility. It is preferably provided that an axial distance between the joint and the cutting area configured with cutting material bodies is smaller than the effective outer diameter of the cutting groups when the cutting material bodies are completely retracted. This results in an axially compact design. In addition, any tilting moments when the tool axis is inclined relative to the axis of rotation of the drive spindle can be kept low, which, according to the inventors' experience, can have a positive effect on the surface quality of the honed inner bore surface. The axial distance is measured in the context of this application between the plane of the hinge point and the axial end of the cutting area.

The invention also relates to a finishing process for machining the inner surface of a bore in a workpiece, in particular for finishing cylinder running surfaces in the production of cylinder blocks or cylinder liners for reciprocating piston machines. The finishing process comprises at least one honing operation in which an expandable honing tool is moved back and forth within the bore to produce a lifting movement in the axial direction of the bore and is simultaneously rotated to produce a rotary movement superimposed on the lifting movement, wherein a honing tool according to the claimed invention is used in the honing operation is used.

According to a further development, a honing operation is carried out as a multi-stage honing operation, the first cutting group being pressed against the inner surface of the bore in a first honing stage and a bore shape which deviates from the circular cylindrical shape, preferably being rotationally symmetrical, is generated using the first cutting group by means of axially uneven material removal, and the second cutting group is then fed in a second honing step and a desired surface structure is produced on the inner surface of the bore by means of the second cutting group, essentially without changing the macro shape of the bore. The honing tool can therefore be used here without changing the tool on the one hand to change the shape of the bore by means of axially uneven material removal (first honing step) and, afterwards, with the first cutting group withdrawn and the second cutting group delivered, to improve the surface structure of the inner bore surface, essentially without further material removal or with at most very little material removal.

Since there is no need for a tool change between the two honing stages, the cycle time can be significantly reduced compared to methods with tool change. In addition, inaccuracies that can be caused by a tool change can be avoided.

In the first honing stage, a path control is preferably used in order to achieve the desired bore shape with high accuracy. In the second honing step, honing is preferably carried out under force control. In some variants, it is provided that honing over the entire length of the bore with an essentially constant pressing force in order to achieve a surface structure that is largely uniform over the entire length.

In other variants, the bore is subdivided in terms of control technology into at least two adjacent axial bore sections (a first bore section and at least a second bore section) and the control is carried out in such a way that the honing parameters differ in the bore sections, e.g. honing in one of the bore sections with greater pressing force than in another bore section. The surfaces in the bore sections can thus be optimized with regard to different conditions during intended use (e.g. piston speed in reciprocating engines).

Figure list

• 1 zeigt eine schrägperspektivische schematische Ansicht einer Ausführungsform eines Honwerkzeugs gemäß der beanspruchten Erfindung;
• 2 zeigt eine Ansicht des Honwerkzeugs aus 1 in Axialrichtung auf das spindelferne Ende;
• 3 zeigt eine Seitenansicht des Honwerkzeugs aus 1;
• 4 zeigt einen Schnitt in einer die Werkzugachse enthaltende Radialebene durch einzeln zustellbare zweite Schneidstoffkörper gemäß Linie IV-IV in 2;
• 5 zeigt einen Schnitt in einer die Werkzugachse enthaltende Radialebene durch erste Träger gemäß Linie V-V in 2;
• 6 zeigt einen Schnitt in einer die Werkzugachse enthaltende Radialebene durch erste Träger einer anderen Ausführungsform;
• 7 bis 10 zeigen verschiedene Varianten von leistenförmigen zweiten Trägern, die im Bereich nahe der Außenfläche zur Befestigung eines Schneidstoffkörpers durch ein Muster von Ausnehmungen und integrale Federelemente elastisch nachgiebig ausgestaltet sind.

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

• 1 shows an oblique perspective schematic view of an embodiment of a honing tool according to the claimed invention;
• 2nd shows a view of the honing tool 1 in the axial direction to the end remote from the spindle;
• 3rd shows a side view of the honing tool 1 ;
• 4th shows a section in a radial plane containing the tool axis through individually deliverable second cutting material body according to line IV-IV in 2nd ;
• 5 shows a section in a radial plane containing the tool axis through first carrier according to line VV in 2nd ;
• 6 shows a section in a radial plane containing the tool axis through first carrier of another embodiment;
• 7 to 10th show different variants of strip-shaped second carriers, which are designed to be elastically resilient in the area near the outer surface for fastening a cutting material body by means of a pattern of recesses and integral spring elements.

DETAILED DESCRIPTION OF THE EMBODIMENTS

1 shows an oblique perspective view of a honing tool 100 according to an embodiment of the invention. The honing tool is used for machining an inner surface of a bore in a workpiece by honing and, in the example, is designed to hone cylinder running surfaces in the manufacture of cylinder blocks or cylinder liners for reciprocating piston machines. The honing tool is particularly well suited for machining rotationally symmetrical bores which have bore sections of different diameters and / or different shapes, for example bottle-shaped bores, barrel-shaped bores and / or bores which have at least one cone-shaped bore section with an axially continuously variable diameter. However, the honing tool can also be used to machine circular cylindrical bores, i.e. rotationally symmetrical bores without an axial contour.

The honing tool has a material body made of a steel material 110 which is a tool axis 112 defined, which is also the axis of rotation of the honing tool during honing. A coupling structure is located at the end of the honing tool on the spindle side 120 for coupling the honing tool to a drive rod or a work spindle of a honing machine or another processing machine which has a work spindle which can be rotated back and forth both about the spindle axis and oscillating parallel to the spindle axis. In 1 is the coupling structure 120 designed as a functional part of a bayonet connection. In embodiments for use on the work spindle of a machining center, for example, a coupling structure in the manner of a hollow shaft cone or another cone can be provided.

In that of the coupling structure 120 or the end section of the tool body facing away from the work spindle (not shown) is the cutting area 130 of the honing tool, in which all abrasive cutting material bodies (general reference number 140 ) are attached. Within the cutting area 130 many cutting material bodies distributed around the circumference of the tool body are arranged, which have an axial length in an axial direction running parallel to the tool axis LS have, which is several times smaller than a minimum effective outer diameter AD of the honing tool in the cutting area equipped with cutting material bodies 130 .

In the exemplary embodiment, all cutting material bodies are designed as narrow cutting material strips in the circumferential direction, whose width BS measured in the circumferential direction is small compared to the axial length LS is. An aspect ratio between length LS and width BS can range, for example, from 4: 1 to 25: 1.

The honing tool has only one cutting area 130 . This is arranged more or less flush with the end of the tool body remote from the spindle in the end section of the tool body facing away from the spindle, so that blind holes can also be machined as far as the bottom of the hole.

With the honing tool 100 in 1 is a honing tool with double expansion, which is characterized in that a first cutting group on the tool body 160-1 and a second cutting group that can be delivered independently 160-2 is arranged. The first cutting group 160-1 has several (exactly four in the example) first carriers 150-1 on that by means of an assigned first delivery system 170-1 in associated radial directions radially to the tool axis 112 can be delivered. The second cutting group 160-2 has several (in the example, a total of eight) second carriers 150-2 on that regardless of the first carriers 150-1 in associated radial directions radially to the tool axis 112 can be delivered, including a second delivery system 170-2 is provided.

With the porters 150-1 , 150-2 that the respective cutting material body 140-1 or. 140-2 wear, it is in each case one-piece, made of steel material components that are essentially rigid. Each of the first carriers 150-1 has a relatively wide carrier section in the circumferential direction 152-1 with a generally cylindrically curved outside 154-1 and a substantially flat inner side facing the tool body, on which a plate-shaped infeed section 156-1 protrudes inside. On the outside 154-1 There are inclined surfaces facing away from the inside of the infeed section, which interact with a corresponding inclined surface of an axially displaceable first infeed cone in the manner of a wedge drive, so that an axial movement of the infeed cone inside the tool body leads to a radial movement of the carrier. The delivery section 156-1 of the carrier 150-1 sits in a radially movable manner in a substantially rectangular recess in the tool body, so that a radial movement (radial to the tool axis 112 ) is possible, but tilting movements in the transverse direction are largely avoided. The carriers are pretensioned into the inwardly retracted position with the aid of several circumferential coil springs, so that the radial inward movement takes place against the force of these return springs.

The outer beam sections 152-1 are so wide in the circumferential direction that the first carriers each cover a circumferential section of more than 20 ° circumferential width, in the example it is more than 30 °, namely about 35 ° circumferential width. In the case of infeed in the radial direction to the workpiece axis, only the central region of this carrier section, viewed in the circumferential direction, is advanced exactly radially to the tool axis. The areas further outside are fed parallel to this central radial direction, so that there is a small angular deviation between the local radial direction and the actual delivery device. Therefore, in many embodiments, the circumferential width is no greater than 45 °, no greater than 60 °, or no greater than 90 °.

The second bearer 150-2 are in the area of their radial outer sides 154-2 significantly narrower than the wide girder sections 152-1 . In the example, they each cover a circumferential angle range of less than 10 °, the circumferential angle range being approximately 5 ° to 7 ° in the example. Absolutely seen the widths can range from 1.5 mm to 4.0 mm, for example. Like the first carriers, the second carriers have a plate-shaped infeed section which projects inwards and, on its tapered inside, inclined surfaces for cooperation with an axially displaceable infeed cone of a second infeed system 170-2 having. Here, too, the feed sections are radially movable, but essentially immovable in the transverse direction in a rectangular recess in the tool body, so that radial displacement is possible and displacements transverse to it are prevented.

The first porters 150-1 each carry six relatively narrow first cutting material bodies on their radial outer sides 140-1 in the form of cutting strips, or the like, with mutual circumferential spacing on the outside of the carrier section, for example by gluing, soldering, screwing. are attached. There are groove-like, axially parallel spaces between the cutting material bodies, the circumferential width of which is smaller than the circumferential width of the respectively adjacent cutting material bodies. With their outer cutting surfaces, the cutting material bodies cover a total circumferential angle range of approximately half or a little more than the circumferential width of the carrier section, so that there is a relatively high surface density of abrasive cutting surfaces in the circumferential direction, but is interrupted by longitudinal gaps that allow the supply and discharge of Favor coolant and possibly abrasion.

Each of the second carriers 150-2 on the other hand carries only a single, relatively narrow cutting material body 140-2 whose axial length determines the axial length of the cutting area. The circumferential width is only approx. 20% of the length, but in the example it is larger than the circumferential width of the many narrower first cutting material bodies in the first cutting group.

The first cutting material bodies 140-1 are in the example of 1 only about half as long as the second cutting material bodies (between 40% and 70% of this length) and close on the side facing away from the spindle at the same height as the second cutting material bodies 140-2 . The first cutting material bodies thereby define an effective first cutting area which is only about half as long as the cutting area 130 whose length is defined by the length of the second cutting material body.

In other embodiments, the shorter first cutting material bodies can also be arranged approximately in the middle of the cutting area or at the upper end of the cutting area facing the coupling section.

The first cutting material bodies are very wear-resistant and preferably have diamond cutting grains in a metallic bond. The second cutting material bodies can be constructed differently, e.g. with ceramic bond or plastic bond.

The honing tool also has a guide group with a plurality of non-cutting guide strips distributed around the circumference of the tool body 180 on, which are fixedly attached to the tool body at predetermined positions, ie cannot be delivered. The guide strips, which are aligned parallel to the tool axis, have an axial length which corresponds approximately to the length of the cutting area and are only within the cutting area 130 arranged. The guide strips made, for example, of hard metal are no longer axially than the cutting material bodies, so that the guide in the axial direction is limited to the area in which material can also be removed. There is no outside the cutting area 130 arranged guide rails. The guide group has six guide strips that are evenly spaced around the circumference of the tool body at 60 ° intervals 110 are distributed. The arrangement is such that each of the guide rails 180 immediately next to a single second cutting material body 140-2 , that is to say an individually deliverable cutting material body of the second cutting group. The distance in the circumferential direction is smaller than the guide width of the respective guide strips measured in the circumferential direction.

Two diametrically opposite guide rails 180-m are designed as measuring strips. They have measuring nozzles in the middle, i.e. halfway up the cutting area 185 of a pneumatic diameter measuring system. Depending on the application, these can also be above or below the center.

Some special features of the honing tool that are not recognizable from the outside can be seen from the sectional views of the 4th and 5 recognizable. It shows 4th a section through a radial plane that goes through the carrier and cutting strips of the second cutting group (with individual strips), while 5 a section through the first carrier 150-1 and first cutting bars 140-1 the first cutting group shows.

The first delivery system 170-1 has an axially displaceable first feed element 172-1 in the form of a tube, which has two axially offset conical sections at the end facing away from the spindle. The first carriers operatively connected to it 150-1 The first cutting group have two inclined surfaces that are axially offset from each other Conical sections work together like a wedge drive. As a result, each first carrier is supported on the associated infeed element in two regions lying at an axial distance from one another, so that tilting of the first carrier is reliably avoided.

The infeed for the second cutting group is solved analogously. The second delivery system has a second delivery element 172-2 in the form of a rod which is guided in the interior of the tube (first feed element) so as to be axially displaceable relative to it. At the end of the rod there are two conical sections at an axial distance from one another. The second bearer 150-2 Correspondingly, they have two axially offset inclined surfaces on their radial inner side, which interact with the corresponding conical surfaces. As a result, tilting of the second carrier during delivery is thus reliably avoided.

As in 6 shown, alternative solutions are also possible in which, for example, the first supports have only a single inclined surface on their radial inner sides, which cooperates with a cone attached to the feed element. The same is also possible for the second carrier.

The sectional views of the 4th to 6 also show another special feature. The honing tool 100 has an integrated joint 190 , with the help of which the tool body 110 is limitedly coupled to the connector, which is used for connection to the work spindle of the processing machine. The joint 190 is formed in the example as a ball joint, in which the joint ball 192 is formed at the lower end of the connector, while the corresponding bearing elements with concave spherical bearing surfaces within the tool body 110 are attached. This allows a limited mobility of the tool body in relation to the connecting piece about an infinite number of directions running transversely to the tool axis, as a result of which the honing tool can follow the surfaces particularly well, especially when reworking inner bore surfaces to improve the surface quality. The axial distance AB between the articulation point (in the center of the articulation ball) or the plane defined thereby, orthogonal to the tool axis and the end remote from the spindle of the cutting area equipped with cutting material bodies 130 is smaller than the effective outer diameter AD of the cutting groups when the cutting material bodies are completely retracted. As a result, the tilting moments that may occur in the event of an offset between the spindle axis and the bore axis can be reduced by a larger distance than conventional designs, which has a positive effect on the machining quality.

The second bearer 150-2 , which carry the individual cutting material bodies of the second cutting group, can be manufactured completely as rigid components made of solid material, for example made of steel. In particular for tracking non-circular cylindrical inner bore surfaces when improving the surface quality by means of the second cutting group, it can be advantageous to incorporate a certain degree of flexibility in the force flow when pressing on the second cutting material bodies, so that pressing force peaks can be avoided.

In the embodiments that are based on the 7 to 10th are shown, this is solved in each case in that the plate-shaped, narrow strip-shaped second carrier near or on the radial outside, which is provided for carrying a narrow cutting material body, an elastically flexible section 150-2E exhibit. The elastic resilience is achieved in these embodiments in that cutouts A of suitable shape, size and distribution are worked out in the initially monolithic carrier by means of spark erosion or in some other way in such a way that the material adjacent to the cutout under external load in the manner of a spring acts elastic so that the outer section 150-2E overall becomes resilient in the radial direction of the carrier. This solution with integral spring elements FE has proven to be particularly robust and durable. The spring force can be adjusted by suitable dimensioning of the recesses or remaining spring elements.

A variant of these designs is based on 8th explained. In this exemplary embodiment, the cutouts are free of carrier material A not empty, but completely with an elastically flexible elastomer material EL filled. This can prevent material abrasion from entering the cutouts. In addition, the spring characteristic can be selected by a suitable choice of the elastic filler material (elastomer material EL ) can be set precisely and any vibrations can be damped. As shown, all recesses or only a part of the recesses can be filled.

The honing tool can be used for a variety of finishing processes to machine the inside surface of a hole with a workpiece. In one variant of the method, the honing tool is provided for the fine machining of cylinder running surfaces in the manufacture of cylinder blocks or cylinder liners for Reciprocating machines to be used, in which, starting from a bore with, for example, a circular cylindrical starting shape, a preferably rotationally symmetrical bore with an axial contour profile is to be produced, i.e. a bore that has different diameters in different axial sections, which merge more or less continuously into one another. It can be, for example, a conical bore shape or a bottle-shaped bore shape or barrel-shaped bore shape.

For this purpose, the honing tool is coupled to the work spindle of a processing machine. In the example, the initial shape is circular-cylindrical and can be produced by honing or also by means of fine machining with a defined cutting edge, for example fine turning. The first cutting group is used in a first honing stage. After inserting the honing tool into the hole, it is pressed against the inner surface of the hole using the first infeed system. Using the first cutting group, a rotationally symmetrical bore shape deviating from the circular cylinder shape is then produced starting from the initial shape by axially uneven material removal. For this purpose, for example, the pressure force as a function of the stroke position of the honing tool in the bore can be varied by means of the control system in such a way that more material is removed in areas with a higher pressure force, so that larger inner diameters are created than in other areas. Alternatively or additionally, an axially non-uniform material removal can be produced by varying the stroke length of the machining strokes, for example by reducing the axial height of the upper reversal point of the stroke movement while the lower reversal point remains the same.

When the desired rotationally symmetrical bore shape has been reached within the specification provided for this first honing step (can be determined, for example, by means of pneumatic diameter measurement), the first cutting group is withdrawn and the second cutting group is fed. In the second honing step that then follows, only a small amount of material or almost no material is removed with the aid of the individual strips of the second cutting group, which are supplied in different radial directions, so that the macro shape of the bore does not change or does not change significantly, but rather only the desired surface structure is created.

In many cases, the finishing process is used to create a rotationally symmetrical bore shape with an axial contour, i.e. axially different diameters, and to generate the appropriate surface structure or surface structure distribution without having to change tools in the meantime. In principle, it is also possible to use the honing tool for producing and / or machining bore shapes that have at least one bore section with a cross-sectional shape that deviates from the circular shape. For example, a bore may have an oval bore shape or a cloverleaf shape in at least one section. Honing tool embodiments suitable for this purpose preferably have only a single pair of diametrically opposed first carriers with corresponding first cutting material bodies (for example full coating or several individual strips at a distance from one another) in the first cutting group, that is to say with the first carriers which are relatively wide in the circumferential direction. The circumferential width is preferably less than 90 or less than 60 °. When producing this type of bore, for example, the pressing force can be varied depending on the rotational position of the honing tool in order to produce areas with a larger diameter by increasing the contact pressure in phases and by reducing the contact pressure to produce areas with a smaller diameter. If necessary, methods according to EP 1 815 943 A1 using vibrational movements.

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102013204714 A1 [0006]
• DE 102014212941 A1 [0008]
• DE 102017202573 A1 [0037]
• EP 1815943 A1 [0075]

Claims (14)

Honing tool (100) for machining an inner surface of a bore in a workpiece using at least one honing operation, in particular for honing cylinder running surfaces in the production of cylinder blocks or cylinder liners for reciprocating piston machines, comprising: a tool body (110) defining a tool axis (112); a first cutting group (160-1) attached to the tool body with a plurality of radially deliverable first carriers (150-1) which can be delivered radially to the tool axis (112) by means of an assigned first cutting group delivery system (170-1), each first carrier covers a circumferential angle range of at least 20 ° on its radial outside and carries a single circumferentially wide first cutting material body or a plurality of narrow first cutting material bodies (140-1) which are arranged at a mutual distance from one another on the outside (154, 454); and a second cutting group (160-2) attached to the tool body with a plurality of radially deliverable second carriers (150-2) which, independently of the first carriers (150-1), radially to the tool axis by means of an assigned second cutting group delivery system (170-2) (112, 412) are deliverable, each second carrier carrying a single narrow second cutting material body (140-2) on its radial outside (154, 454), wherein all cutting material bodies (140-1, 140-2) of the first and the second cutting group are arranged in an axially short cutting area (130) which has a length measured in the axial direction which is substantially smaller than an effective outer diameter (AD) of the cutting groups with completely retracted cutting material bodies. Honing tool Claim 1 , characterized in that the first cutting material bodies (140-1) attached to a first carrier (150-1) cover with their outer cutting surfaces a total circumferential angle range which is at least 30% or at least 50% of the circumferential width of the outside (154-1) of the first carrier. Honing tool Claim 1 or 2nd , characterized in that each first carrier (150-1) carries on its radial outside more than two first cutting material bodies (140-1), preferably three, four, five, six or seven first cutting material bodies (140-1), and / or that a mutual distance between immediately adjacent first cutting material bodies (140-1) is of the order of magnitude of the circumferential width of the first cutting material bodies or less. Honing tool according to one of the preceding claims, characterized in that at least one second carrier (150-2) is arranged between first carriers (150-1) which are adjacent in the circumferential direction. Honing tool according to one of the preceding claims, characterized in that the first carrier (150-1) and the second carrier (150-2) are arranged unevenly distributed in the circumferential direction. Honing tool according to one of the preceding claims, characterized in that the first cutting material bodies (140-1) are shorter in the axial direction than the second cutting material bodies (140-2), an axial length of the first cutting material bodies preferably being less than 80% and / or more than 50% or axial length of the second cutting material body is. Honing tool according to one of the preceding claims, characterized in that the honing tool has an integrated joint (190) for coupling the tool body (110) to a connecting piece with limited mobility, preferably an axial distance (AB) between an articulation point of the joint (190) and an end of the cutting area (130) remote from the spindle is smaller than the effective outer diameter (AD) of the cutting groups when the cutting material bodies are completely retracted. Honing tool according to one of the preceding claims, characterized in that the second cutting material bodies (140-2) are elastically resiliently mounted with respect to the tool body (110), the second carrier (150-2) preferably being close to or adjacent to a second cutting material body has an elastic section (150-2E) with recesses (A) and spring elements (FE) formed in one piece with the carrier. Honing tool according to one of the preceding claims, characterized by a guide group with a plurality of guide strips (180) distributed around the circumference of the tool body, the guide strips (180) preferably being arranged exclusively within the cutting area (130). Honing tool Claim 9 , characterized in that one, several or all of the guide strips (180) are arranged directly next to a second carrier (150-2), a circumferential distance between a second carrier (150-2) and the guide strip (180) preferably being less than the width of the Guide bar is in the circumferential direction. Honing tool according to one of the preceding claims, characterized in that the first cutting group infeed system (170-1) and / or the second cutting group infeed system (170-2) has an axially displaceable infeed element which has a first conical section and axially offset from it has second conical section, the first carrier (150-1) and / or the second carrier (150-2) having on their radial inside two axially offset inclined surfaces which are designed to interact with the first and the second conical section. Finishing process for machining the inner surface of a bore in a workpiece, in particular for finishing cylinder running surfaces in the manufacture of cylinder blocks or cylinder liners for reciprocating piston machines, the finishing process comprising at least one honing operation in which an expandable honing tool (100) within the bore for generating a lifting movement in Axial direction of the bore moved back and forth and simultaneously rotated to produce a rotary movement superimposed on the lifting movement, characterized in that a honing tool (100) with the features of at least one of the preceding claims is used in the honing operation. Finishing process after Claim 12 , characterized in that a honing operation is carried out as a multi-stage honing operation, a first cutting group being pressed against the inner surface of the bore in a first honing stage and using the first cutting group using axially uneven material removal starting from an initial shape and producing a preferably rotationally symmetrical bore shape which deviates from a circular cylindrical shape, and that a second cutting group is then delivered in a second honing step and a desired surface structure is produced on the inner surface of the bore by means of the second cutting group, essentially without changing the macro shape of the bore. Finishing process after Claim 13 , characterized in that in the first honing stage is honed with a path control and / or in the second honing stage is force-controlled.

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