WO2018149696A1

WO2018149696A1 - Honing tool and fine machining method using the honing tool

Info

Publication number: WO2018149696A1
Application number: PCT/EP2018/052943
Authority: WO
Inventors: Josef Schmid
Original assignee: Elgan-Diamantwerkzeuge Gmbh & Co. Kg
Priority date: 2017-02-17
Filing date: 2018-02-06
Publication date: 2018-08-23
Also published as: US20190366504A1; CN110520247A; HUE064435T2; EP3582931A1; EP3582931B1; DE102017202573A1; CN110520247B

Abstract

A honing tool (100) for machining an inner surface (322) of a borehole (320) in a workpiece (300) with the help of at least one honing operation comprises a tool body (110), which defines a tool axis, and an expandable cutting group (330), which is attached to the tool body and has a plurality of cutting material body supports (150), which can be radially advanced and which each cover a circumferential angle range, and can be radially advanced with respect to the tool axis by means of a cutting group advancing system associated with the cutting group. Each cutting material body support carries, on its radial outer side, a plurality of narrow cutting material bodies (140), which are formed as narrow cutting material strips (140-1, 140-2, 140-3, 440-1, 440-2) in the circumferential direction and have a width, in the circumferential direction, that is small in relation to the axial length of the cutting material strips. The cutting material bodies are arranged spaced apart from each other. In an intermediate space between a cutting material body (140) and the cutting material body support (150) that carries the cutting material body, an elastically yielding intermediate layer (160) is arranged that fills the intermediate space between the cutting material body and the cutting material body support. A preferred area of application is the honing of cylinder running surfaces during the production of cylinder blocks or cylinder liners for reciprocating piston machines.

Description

Honing tool and finishing process using the honing tool

APPLICATION AND PRIOR ART K

The invention relates to a honing tool according to the preamble of claim 1 and a finishing method according to the preamble of claim 13. A preferred field of application is the fine machining of cylinder surfaces in the manufacture of cylinder blocks or cylinder liners for reciprocating engines.

The cylinder surfaces in cylinder blocks (cylinder crankcases) or cylinder liners of internal combustion engines or other reciprocating engines are exposed during operation of a strong tribological stress. Therefore, it is important in the production of cylinder blocks or cylinder liners to edit these cylinder surfaces so that later in all operating conditions sufficient lubrication is ensured by a lubricant film and the frictional resistance between relatively moving parts is minimized.

The quality-determining finishing of such tribologically stressable inner surfaces is usually carried out with suitable honing methods, which typically comprise several successive honing operations. Honing is a machining process with geometrically indeterminate cutting edges. In a honing operation an expandable honing tool is moved within the bore to be machined to generate a stroke in the axial direction of the bore with a stroke frequency up and down or back and forth and simultaneously rotated to produce a lifting movement superimposed rotary motion at a rotational frequency. The cutting material bodies attached to the honing tool are pressed against the inner surface to be machined via a cutting material body feed system with a feed force acting radially to the tool axis. During honing, the honing process generally produces a cross-cut pattern with intersecting machining marks, also referred to as "honing marks." Pre-machining by precision boring, sometimes also known as "honing", can be used to prepare the workpieces to be worked Fine boring operations carried out with precision boring tools with a geometrically determined cutting edge usually serve to determine the desired position and angular position of the borehole, if necessary also for producing bore shapes that are of a circular cylindrical shape An essential task of the honing operation with a smaller oversize compared to fine boring is the generation of the required surface structure.

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 holes and the surface structure is of particular importance.

In some finishing processes, a bore shape deviating from the circular cylindrical shape is produced by means of fine boring and / or honing. Such bore shapes are usually asymmetric in the axial direction and / or in the circumferential direction, because the deformations of the cylinder block are usually not symmetrical. In the operating state, an ideal circular cylindrical shape should usually result, so that the piston ring package can seal well over the entire bore circumference.

Due to different requirements different honing tool types were developed. They can be distinguished first in honing tools, which can be delivered during processing, and honing tools, which are presettable. Honing tools that can be delivered during processing can be subdivided further into strip honing tools, such as single-bar honing tools, multi-bar honing tools and special tools, and into largely full-surface tools, such as cup tools and shank tools. The category of presettable honing tools includes the so-called mandrel tools or Precidor honing tools.

Single-bar honing tools are often used in the machining of high-precision small parts. Multi-bar honing tools are available for various applications in a wide variety of designs. Due to the high cutting agent volume and their use parameters, high metal removal rates can be achieved during honing.

When drilling with large interruptions, the use of classic grooved hone tools can lead to problems. Although the individually guided honing stones can provide concentric expansion and optimum roundness of the bore, there is a risk of them catching in the workpiece in the event of major interruptions. Among other things, for these applications, the so-called shell tools have been developed in which cutting means are arranged on a circumferentially relatively wide cutting material body carrier. One Shell tool can be constructed, for example, with only two Schneidstoffkörper carriers (half shells), possibly with three or four or more Schneidstoffkörper carriers correspondingly smaller circumferential width. Shell tools can be designed with different designs.

The publication DE 1652074 describes a honing tool with shell segments, which are made with a single piece chipping as a sintered part and which can have a plurality of outwardly projecting ribs as a carrier for the machining lining.

DE 102013204714 A1 discloses e.g. Honing tools designed as shell tools, which are suitable for machining, rotationally symmetrical bores, which have bore sections of different diameter and / or shape. Thereby, e.g. Holes with bottle shape, cone shape or barrel shape machined and / or produced. The honing tool has an expandable annular cutting group with a plurality of cutting bodies distributed around the circumference of the tool body whose axial length measured in the axial direction is smaller than an effective outside diameter of the cutting group with the cutting bodies completely retracted a plurality of radially deliverable Schneidstoffkörper carrier, each covering a circumferential angular range which is greater than the axial length of the cutting group.

Due to the relatively short axial length of the cutting group such honing tools are particularly well suited for the generation of an axial contour and / or for tracking an existing axial contour of the bore. In addition, small axial lengths of the cutting group may be advantageous to produce sufficient surface pressure for machining. The fact that the cutting group has a plurality of radially deliverable Schneidstoffkörper- carrier, each covering a circumferential angle range which is greater than the axial length of the cutting group, can be achieved, inter alia, that, for example, transverse bores in the wall of a cylinder bore during honing in the circumferential direction can be bridged , so that despite axially short cutting material body does not run the risk of uneven machining in the range of cross holes. In addition, with the use of such honing tools, very little honing overflow can be made at the axial ends of a bore without problems of uneven cutting body wear. However, it has been observed that in some cases when machining non-cylindrical holes (eg holes with bottle shape, cone shape or barrel shape) locally different surface structures due to different cutting depths can be generated. These can cause technical disadvantages. In the case of undesired excessively high local roughness, eg oil consumption and blow-by can be increased. If locally too little removal of material is generated, the risk of chilling during operation of an internal combustion engine may increase due to too little removal of material damage from upstream processing stages. In the vicinity of the axial ends of a bore, deviations of the grinding pattern from the grinding pattern in the rest of the bore may occur.

TASK AND SOLUTION

It is an object of the present invention to provide a generic honing tool and a fine machining method that can be performed therewith, which allow holes of different shapes to be machined such that the machined bore surfaces have a well-defined surface structure over the entire bore length.

To solve this problem, the invention provides a honing tool having the features of claim 1. Furthermore, a finishing method having the features of claim 13 is provided. Advantageous developments are specified in the dependent claims. The wording of all claims is incorporated herein by reference. The attached to the tool body, expandable cutting group has a plurality of radially deliverable cutting material body support, each covering a circumferential angular range and are radially deliverable by means of the cutting group associated cutting group delivery system to the tool axis. The circumferential angle range can be e.g. at 30 ° or more, at 40 ° or more, or at about 60 ° or more, or even at 90 ° or more. Each cutting material body carrier carries on its radial outer side a plurality of narrow cutting material bodies, which are arranged with mutual lateral spacing from one another and in each case cover only a fraction of the circumferential angle range. Between the cutting material bodies thus gaps or gaps remain without cutting material. As a result, a reliable lubrication with coolant and a sufficient removal of processing residues can be ensured even with heavy material removal.

The cutting material body are formed as circumferentially narrow cutting strips whose width in the circumferential direction is small compared to the axial length of the cutting strips. If necessary, a particularly uniform cover over the entire bore length can be achieved, even at the bore ends where a honing overflow may be desired. An aspect ratio between the axial length and the width to be measured in the circumferential direction may be, for example, in the range of 4: 1 to 20: 1.

The cutting bodies may consist entirely of cutting means or may be made of e.g. comprising metal carrier carrying the cutting means. The cutting means may e.g. Diamond or cubic boron nitride (CBN) cutting grains bonded in a metallic or ceramic matrix.

The cutting group has cutting material body, which are not directly or directly applied to the radial outer side of the associated Schneidstoffkörper carrier and not rigidly connected thereto. Rather, it is provided that in an intermediate space between a cutting material body and the cutting material body carrying Schneidstoffkörper- carrier an elastically resilient intermediate layer is arranged, which fills the gap between the cutting fabric body and the cutting material body carrier.

Such an intermediate layer may be provided in all cutting bodies of a cutting group. It is also possible that only a portion of cutting material bodies of a cutting group is supported by such an intermediate layer and another portion is rigidly connected to the cutting body carrying it. Preferably, all of the cutting material body of a cutting material body carrier are either resiliently connected via an elastic intermediate layer with the associated Schneidstoffkörper carrier or all are rigidly attached to this, so that there is no mixture of rigid and flexible coupled cutting material bodies on a cutting material body.

Each cutting material body carrier thus carries a cutting material body group with two, three, four, five, six, seven, eight or more relatively narrow cutting bodies, between which gaps remain in the circumferential direction. The cutting material body group (group of cutting material bodies) is supported by the substantially rigid cutting material body carrier, so that all cutting bodies of the cutting material body group are delivered together radially when the cutting body carrier is delivered radially. The requirement for radial deliverability of the cutting material body carrier requires that the carrier must be movably mounted relative to the workpiece body, wherein above all a mobility in the radial direction is required. However, a certain tilting of a cutting material body carrier can not be completely excluded, for example in the area of the honing overflow, since an unequal loading of the cutting material body and thus of the associated cutting material body carrier arises there in the axial direction. Due to the elastically yielding intermediate layers between the cutting material bodies and the cutting material body carrier carrying them, individual flexibility or mobility of the cutting material body relative to the supporting (rigid) cutting material body carrier and relative to other cutting material bodies of the cutting material body group is given to a certain extent. It has been found that, as a result, the adaptability of the honing tool or of the cutting material body to different orientations of the surface to be processed compared to conventional solutions can be further improved.

Improvements may arise, in particular, in conical shapes and / or in the region of axial transitions between cylindrical and conical bore sections and / or in the region of axial transitions between sections of different cone angles.

Furthermore, the cutting material body may possibly also existing deviations from the

Roundness of the hole in oval bore shapes or roundness deviations higher

Better to follow order. Optionally, improvements may also result in the area of the reversal point of the axially reciprocating honing movement, that is, where at

Direction change a tilting moment on the arrangement of cutting material bodies and the bearing cutting material body carrier may arise.

Among other things, it can be achieved by the intermediate layer that a cutting material body remains largely parallel to the machined bore surface, despite a tilting moment possibly acting on the overall arrangement (cutting material body carrier with cutting material bodies), whereby a well-definable uniform surface structure also in axial transition regions of different surface orientation and up to the axial bore ends can be ensured. Due to the fact that the intermediate layer fills the gap between the cutting material body and the cutting material body carrier, no abrasion between cutting material body and cutting material body carrier can reach, so that the individual flexibility is maintained even with heavy material removal over the entire honing process. Likewise, the surface damage caused by scratches and / or grooves can thus be prevented, which can occur due to the interposition of abrasion and / or coarse cutting grains or foreign bodies in the recesses of sprung strip carriers.

Honing tools according to the invention are particularly suitable for honing holes with an axial contour. The individually flexibly or flexibly mounted cutting material body can adapt particularly well to changing in the axial direction of the bore inclinations of the bore inner surface, eg at the transition between a circular cylindrical bore portion and a conical bore portion. Honing operations in which the cutting material bodies are intended to follow the contour of the bore as well as possible without changing the macroscopic shape of the bore are also referred to here as "trailing honing." Honing of non-round bore shapes with deviations from the rotational symmetry can also provide the advantages of inventive honing tools be used.

It has been determined by numerous experiments that it is generally favorable if the intermediate layer has a layer thickness which is in the range of 0.1 mm to 2 mm, in particular in the range of 0.5 mm to 1 .5 mm. In the case of layer thicknesses that are significantly below the lower limit, the tiltability of the cutting material body in relation to the cutting material body carrier element that can be achieved as a result is generally insufficient to be able to compensate for all misorientations that occur. With layer thicknesses which are clearly above the upper limit, it becomes more difficult to obtain sufficient stability of the cutting edges against transverse loads. In order to allow a good compromise between sufficient stability of the intermediate layer against transverse loads and sufficient flexibility to compensate for misalignments, it has proven to be advantageous if a Shore hardness of the intermediate layer in the range of about 70 Shore A to 95 Shore A. , For larger hardnesses a sufficient yield is usually no longer given. At significantly lower hardnesses, the arrangement of the cutting material strips on the cutting material body support element can become too unstable, so that when honing not sufficient machining forces can be brought to the surface to be machined.

In preferred embodiments, the intermediate layer has an elastic layer of an elastomer, in particular of a rubber-elastic polyurethane elastomer. The term "elastomer" here stands for dimensionally stable, but elastically deformable plastics whose glass transition point is below the operating temperature.An elastomer can deform elastically under tensile and compressive loading, but then returns to its original undeformed shape Adhesive elastomers are particularly easy to use An advantage of polyurethane elastomers lies in the particularly high resistance of the material properties to the influence of typical cooling lubricants. In some embodiments, it is provided that the intermediate layer is vulcanized directly onto a contact surface on the cutting material body or onto the outer surface of the cutting material body carrier element. In this case, no further material (such as a primer or an adhesive) is needed to make the bond between the intermediate layer and the adjacent element. The surface connection with the other element (cutting material body or outer surface of the cutting material body-carrier element) can be realized for example by a thin adhesive layer.

In some embodiments, the intermediate layer has a multilayer structure. In particular, the intermediate layer may be constructed such that it has a first layer and at least one second layer connected thereto in a planar manner, wherein the first layer is a layer of an elastomer and the second layer is an adhesive layer connected in a planar manner to the first layer.

Although it is possible that the adhesive layer (second layer) is thicker than the elastomer layer (first layer), it is preferably provided that the layer thickness of the first layer is larger than the layer thickness of the second layer. It can thereby be achieved that the essential contribution to the desired elasticity or flexibility of the cutting material body relative to the cutting material body carrier element is determined by the properties of the first layer (elastomer layer).

It is possible that an optionally relatively small contribution to the overall elasticity of the intermediate layer is made by the adhesive layer. This can be achieved by the adhesive layer itself being elastically deformable. To produce the adhesive layer, for example, viscoplastic adhesives, for example a viscoplastic two-component acrylate-based plastic adhesive, can be used. When selecting the material for the adhesive layer, it should preferably be ensured that there is good adhesion to the material of the cutting material body and / or to the material of the outside of the cutting-material body-carrier element.

To improve the adhesion at a splice, at least one of the surfaces adjacent the adhesive layer may be roughened by sandblasting or grinding or otherwise by applying the adhesive. The average roughness depth R _{z of} a surface of a cutting material body carrier made of steel, for example, and / or of the cutting material body adjacent to the adhesive layer is preferably in the range from R _z = 10 μm to R _z = 30 μηι. As a result, permanently high adhesive strengths can be achieved. Also, the adhesive coming into contact surface of the intermediate layer material (eg plate or strip of Polyurethane elastomer) can be roughened beforehand. Mean roughness depths in the range of R _z = 15 μηη to R _z = 40 μηη have proven to be particularly favorable.

The invention can be used with different honing tool types. For example, the cutting body carriers can be longer in the axial direction than in the circumferential direction. In contrast, in many embodiments, the cutting group has an axially measured axial length which is less than an effective outer diameter of the cutting group for fully retracted cutting bodies. Such a cutting group may be referred to as an annular cutting group. Even with an annular cutting group cutting material body can be formed as circumferentially narrow cutting strips whose width in the circumferential direction is small compared to the axial length of the cutting strips.

The honing tool preferably has exactly one single annular cutting group. An annular cutting group can be designed so that in the axial section covered by the annular cutting group substantially more contact surface between cutting bodies and bore inner surface may exist than in a comparatively narrow axial section of a conventional honing tool with relatively narrow honing stones.

The axial length of the cutting material body may be, for example, less than 40% or less than 30% of the effective outer diameter of the honing tool, in particular between 15% and 30% of this outer diameter. For honing tools for machining typical cylinder bores in engine blocks for cars or trucks, the axial length may be, for example, in the range of 5 mm to 40 mm, in particular 10 mm to 35 mm. For example, based on the bore length of a bore to be machined, the axial length may be less than 20% or less than 10% of that bore length. For example, based on the bore diameter of a bore to be machined, the axial length may be in the range of 20% to 50% of the bore diameter.

Since in such an annular cutting group the cutting material body in the axial direction are relatively short compared to conventional honing stones, even with stable intermediate layers with a relatively small thickness (eg 0.5 mm to 1, 5 mm) can adjust sufficiently strong inclination angle between cutting material body and tool axis, which promotes a special contour tracking capability. If at least three cutting body supports are provided in the cutting group, the machining forces can be distributed well and relatively uniformly over the circumference of the cutting group over the entire effective outer diameter of the honing tool available by means of expansion. For example, in the cutting group exactly three, exactly four, exactly five, exactly six, exactly seven or exactly eight cutting material body carriers of the same or different circumferential width can be provided. Although more than eight cutting material carriers within a cutting group are possible, they make the design more complicated and are generally not required. In some cases, it may also be sufficient if the honing tool has only two Schneidstoffkörper- carrier.

There are exemplary embodiments in which all cutting material body carriers or all cutting material bodies of the honing tool can be delivered radially with a single common infeed. Such honing tools are referred to as honing tool with simple expansion. Other embodiments are characterized in that the honing tool is designed as a honing tool with double widening. In such honing tools, the cutting assembly includes a first group of cutting material body carriers and a separate second group of cutting material carriers, the first group and the second group being independently deliverable. When using a honing tool with double widening fine machining methods are possible in which each of the cutting material body carriers of a group are delivered together radially and withdrawn. As a result, for example, one of the groups can be disengaged from the bore inner surface by retraction, so that the bore inner surface is machined only by the other group. It is also possible to machine the bore inner surface at the same time as all the cutting material bodies of the first and the second group. The use of a double widening honing tool offers the potential for shortening cycle times, as it may eliminate the need for tool changes between successive different honing operations. In some embodiments, an initial first honing operation is performed first with the first group, this first group is thereafter withdrawn, the other group (second group) is preferably delivered radially outward at the same time as the first group is retracted, and thereafter with the cutting material bodies becomes the second Group performed a subsequent second honing operation.

The cutting material body of the first and the second group can have different overall removal characteristics or other properties specific to the material removal. For example, the cutting body of the two groups may have different widths and / or be mounted with different circumferential distances and / or different pitch on the respectively associated Schneidstoffkörper carriers. It is alternatively or additionally also possible that the cutting material body of one of the groups for a coarser machining with coarser grain and the cutting material body of the other group are equipped for finer processing with finer grain. Thus, it is possible, for example, to carry out a pre-honing operation with substantial material removal and a downstream prefabricated honing operation with less or almost no material removal predominantly for smoothing the previously structured surface in succession with the same honing tool. Some embodiments of double-widening honing tools are distinguished by the fact that in the first group the cutting-material bodies are fastened directly to the associated cutting-material body carrier without the interposition of an elastic intermediate layer and are thus rigidly connected to the cutting-material body carrier, whereas in the second group the cutting-material bodies are individualized are resiliently attached via an elastic resilient intermediate layer on the associated cutting material body-carrier. For example, with the double widening, it is possible to first use the first group to perform a first honing operation designed as a contour honing operation to selectively alter the axial contour of the bore from a previous machining operation. Thereafter, the first group out of engagement and the second group are brought into engagement with the bore inner surface to perform a second honing operation in the form of a Nachlaufhon operation with the second group, in which only weakly abrasive and elastically yielding cutting material body of the previously generated contour in Trace essentially and improve the surface structure in the first place.

The invention also relates to a fine machining method for machining the inner surface of a bore in a workpiece, in particular for fine machining cylinder surfaces in the manufacture of cylinder blocks or cylinder liners for reciprocating engines. In the course of the finishing process, at least one honing operation is performed, in which an expandable honing tool moves up and down within the bore to produce a stroke in the axial direction of the bore and at the same time is rotated to produce a rotational movement superimposed on the lifting movement. In this honing operation, a honing tool according to the claimed invention is used. This honing operation is preferably the last finishing operation of a multi-stage finishing process and substantially determines the surface structure of the final product. Before starting the honing operation, a bore shape that deviates significantly from a circular cylindrical shape can be produced by fine boring (with geometrically determined cutting edge), honing (with geometrically indeterminate cutting edges) or by a combination of both fine machining processes (eg first fine boring, then honing). For example, the bore may be preprocessed to obtain an axial contour (eg, barrel shape, bottle shape, or cone shape) and / or one or more sections of deliberately non-circular shape (eg, oval shape or cloverleaf) before the honing operation begins. The honing operation can then be carried out in a substantially shape-retaining manner such that the final desired surface structure is produced on the bore inner surface essentially without changing the macro-shape of the bore using the honing tool. In this case, the cutting material bodies follow the predetermined surface shape or follow this, resulting in a particularly good Nachverfolgsignung by the individually compliant storage of the individual cutting material body. BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and aspects of the invention will become apparent from the claims and from the following description of preferred embodiments of the invention, which are explained below with reference to the figures. Showing:

Fig. 1 is a diagonal perspective schematic view of an embodiment of a

Honing tool according to the claimed invention;

2 is a schematic sectional view through a part of a Schneidstoffkörper-

Carrier, on the outside of which several strips of cutting material are each fastened with the interposition of an elastically yielding intermediate layer;

Fig. 3 is a schematic representation of a processing situation in the area of

Transition between a cylindrical and a conical section of a rotationally symmetrical bore with an axial contour;

Fig. 4 is an axial view of another embodiment of a honing tool;

Figure 5 is a schematic sectional view through part of a Schneidstoffkörper- carrier on the outside of an elastically resilient layer is applied, which carries a plurality of cutting material body, and an enlarged detail. 6 shows in FIGS. 6A and 6B a first exemplary embodiment with a laterally inhomogeneous intermediate layer; and

Fig. 7-9 further embodiments with laterally inhomogeneous intermediate layer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The diagrammatic FIG. 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 means of honing and, in the example, is designed to honing cylinder running surfaces in the manufacture of cylinder blocks or cylinder liners for reciprocating engines. The honing tool is also particularly suitable for machining rotationally symmetrical boreholes 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 for machining circular cylindrical bores, ie rotationally symmetrical bores without axial contour progression.

The honing tool has a made of a steel material material body 1 10, which defines a tool axis 1 12, which is also the axis of rotation of the honing tool during honing. At the spindle-side end of the honing tool is a coupling structure 120 for coupling the honing tool to a drive rod or a work spindle of a honing machine or other processing machine, which has a work spindle, which is both oscillating about the spindle axis and parallel to the spindle axis back and forth movable ,

In embodiments for use on the work spindle of a machining center, e.g. a coupling structure may be provided in the manner of a hollow shaft cone or another cone.

At the end portion facing away from the spindle of the tool body is an expandable annular cutting group 130 having a plurality of distributed around the circumference of the tool body Schneidstoffkörpern 140-1, 140-2, etc., measured in the axial direction axial length LS is smaller by a multiple than an effective outer diameter AD the cutting group 130 at completely retracted in the radial direction cutting bodies. The Cutting material body 140-1 etc. are formed as narrow cutting strips in the circumferential direction whose width BS measured in the circumferential direction is small compared to the axial length LS of the cutting material strips. An aspect ratio between length LS and width BS may be in the range of 4: 1 to 20: 1, for example. In terms of absolute values, the length may be, for example, in the range of 10 mm to 20 mm and the width in the range of 2 mm to 5 mm.

The honing tool has only a single annular cutting group 130. This is arranged more or less flush with the spindle distal end of the tool body, so that, if necessary, even hole bores can be edited to the bottom of the hole. Shown dashed is an optional existing slender coupling portion at the spindle end facing away from the honing tool. This coupling portion may e.g. be used as coding element in the context of an automatic tool change.

The cutting group or the cutting material body of the cutting group are fed by means of a cutting group associated with the cutting group delivery system radially to the tool axis. Since this functionality, which is typical for honing tools, is known per se, the components provided for this purpose (for example, feed rod (s), expansion cone, etc.) will not be described in more detail here.

The expandable annular cutting assembly 130 includes a plurality of radially deliverable cutting material body supports 150-1, 150-2, etc., each covering a circumferential angular range greater than the axial length LS of the cutting material body or cutting group. In the example of FIG. 1, six cutting material body carriers 150-1 to 150-6 are provided, which each cover a circumferential angle range of between 45 ° and 60 ° and are arranged uniformly over the circumference of the honing tool.

Between immediately adjacent cutting material body carriers non-cutting guide strips 1 15-1 etc. are attached to the tool body. 1 shows the honing tool 100 with retracted cutting material bodies, so that the outer surfaces of the guide strips serving as guide surfaces project beyond the abrasive outer surfaces of the cutting material bodies in the radial direction. Before and / or during the honing process, the cutting-material-body carrier elements are delivered radially outwards so that they engage with the inner surface of the bore to be machined.

The cutting material body support are made in one piece from a steel material in the example and therefore essentially rigid in itself. Each cutter body carrier has one in the circumferential direction relatively wide support portion 152-1, etc. with a cylindrically curved outer side 154 and a tool body facing, substantially flat inside, on which a plate-shaped feed portion 156 projects inwardly. On the outside of the outer side 154 facing away from the Zustellabschnitts is an inclined surface which cooperates with a corresponding inclined surface of an axially displaceable Zustellkonus like a wedge drive, so that an axial movement of the Zustellstange inside the tool body leads to a radial movement of the cutting material body carrier. The Zustellabschnitt 156 of the cutting material body-carrier sits radially movable in a substantially rectangular recess of the tool body, so that a radial movement possible, but tilting movements in the transverse direction to be largely avoided. The cutting body carriers are biased by means of a plurality of rotating coil springs in the retracted inward position, so that the radial outward delivery takes place against the force of these return springs.

There are exemplary embodiments in which all cutting material body carriers or all cutting material bodies of the honing tool can be delivered radially with a single common infeed (honing tools with simple widening).

In the embodiment of the honing tool 100 in Fig. 1 is a honing tool with double widening. The annular cutting group 130 has two independently deliverable groups of cutting body carriers, wherein the three cutting body carriers of a group are circumferentially offset from each other by 120 ° so that a cutting material body carrier of the other group is arranged between two adjacent cutting body carriers of one of the groups is.

Special design precautions have been taken on the honing tool which can help to optimize the machining result on the holes machined with the honing tool so that over the entire bore length, in particular also in the area of transitions between bore sections of different shape and / or in the area of reversal points the axial Honbewegung the desired surface structure can be produced with relatively uniform quality.

As can be seen in FIG. 1, each cutting-material-body carrier has on its radial outer side 154 a plurality of cutting-material bodies in the form of cutting-material strips which are arranged with mutual circumferential spacing from one another. These cutting material body groups or strip groups of cutting material strips mounted together on a cutting material body carrier can, for example, consist of between three and ten cutting strips consist. In the example case, seven cutting strips are arranged uniformly spaced from one another on each cutting-material body carrier. The circumferential distance is in the narrower cutting strips approximately in the order of the width of the cutting strips or above, in the wider cutting strips about the size of the width of the cutting strips or below.

The cutting material bodies are not rigidly connected to the cutting material body carrier carrying them. Instead, there is a gap between each of the cutting edges and the cutting material carrier carrying the cutting strip, in which an elastically flexible intermediate layer 160 is arranged, which substantially completely fills the gap between the cutting strip and the cutting element carrier element. Due to the elastically yielding intermediate layer, it is achieved that the cutting material bodies can move to a limited extent and to a limited extent against the restoring force through the intermediate layer relative to the cutting material body carrier during external loading. The cutting strips each have individual flexibility, so they can each shift slightly regardless of the adjacent cutting strips.

The intermediate layer has in the example a layer thickness SD of about 1 mm, whereby a good compromise between sufficient flexibility and sufficient stability of the cutting material against transverse forces can be achieved. The intermediate layer essentially consists of a rubber-elastic polyurethane elastomer having a hardness in the hardness range of between 75 and 85 Shore A. Suitable elastic polyurethane plastics are commercially available, for example, under the trade name Vulkollan® or Urepan®. The interlayer material is pore-free, so dense, so that no cooling lubricant can penetrate and the elastic properties remain permanently stable. The material is also chemically resistant to cooling lubricants and mechanically sufficiently resistant to the abrasion of the honing process in the harsh machining environment.

It is possible, in the manufacture of the honing tool prefabricated narrow thin strips of the interlayer material first stick to the outside of the Schneidstoffkörper- carrier and then stick the designated formförmigem Schneidstoffkörper (cutting strips) with a suitable adhesive. A variant of the production comes without adhesion promoter between the intermediate layer material and the cutting material bodies. In this variant, first a plate made of cutting material body material is produced. Thereafter, on the attachment side (contact side) provided side, a layer of the precursor of finished intermediate layer material vulcanized so that a mechanically strong adhesive contact between the cutting material body material and the intermediate layer material is formed by the vulcanization. Subsequently, the individual, each provided with intermediate layer cutting material body can then be prepared by separating the coated cutting material body plate. It would also be possible to provide individual cutting strips each on one side with a vulcanized elastomer layer and then glue these onto the cutting material body-carrier element.

It is also possible firstly to coat the outside of a cutting-material-body carrier element with a layer of intermediate layer material more or less completely (for example by gluing) and then to adhesively secure the cutting-material strips in the places provided for this purpose. The intermediate layer material then remains between adjacent strips of cutting material (see FIG. 5).

For the preparation of a sheet bond between a cutting body and a strip of elastic interlayer material and / or an adhesive bond between an intermediate layer of polyurethane plastic and the outside of the cutting body-carrier element, in preferred embodiments a tough, two-component acrylate-based construction adhesive is used. The resulting bond is characterized by high adhesion. In addition, the adhesive layer is slightly elastic in itself, so that a multi-layer elastic resilient intermediate layer is formed, which offers good adhesion even after permanent cycling.

An improvement in the adhesive strength can be achieved if the surfaces of the intermediate layer material, the cutting material body carrier and / or the cutting material body coming in contact with the adhesive have a relatively rough surface structure. If necessary, the surfaces can be roughened by grinding, sandblasting or in some other way prior to application of the adhesive, for example to average roughnesses in the range from R _z = 15 μηη to R _z = 30 μηη.

By interposing an elastically resilient intermediate layer between the cutting strips and the cutting material body support elements, the ability of the honing tool for contour tracking in the processing and / or production of holes with axial contour can be generally improved, since the cutting strips relative to the rigid cutting material body support element slightly align and so can achieve a more uniform contact pressure on the bore inner surface. A special phase of the processing is shown schematically in FIG. A section of a workpiece 300 in the form of an engine block (cylinder crankcase) for an internal combustion engine can be seen. The bore 320 to be machined is delimited by a bore inner surface 322. The bore inner surface is the workpiece surface to be machined during honing. The bore 320 is rotationally symmetrical with respect to its bore axis, not shown, and extends over a bore length from the illustrated, in the installed state the cylinder head facing bore inlet 314 to an axially opposite bore outlet. The bore can be subdivided into a plurality of axially adjacent bore sections of different function, which merge into one another without the formation of steps or edges. Immediately at the bore entry 314 begins a first bore portion 322, which should have a substantially circular cylindrical shape, so no axial contour course after completion of the processing. A conical second bore section 324, in which the bore diameter continuously increases from the inlet side in the direction of the outlet side, adjoins this circular-cylindrical bore section in the direction of the opposite bore end. The conical bore section can extend to the bore exit. It is also possible for the conical bore section to be adjoined by a further substantially circular-cylindrical section, which then has a larger diameter than the inlet-side first bore section 322. In such a case, the bore would then have at least approximately a bottle shape. The transition areas between the bore sections are (in deviation from the schematic drawing) continuously curved. There may be convex or concave transition areas.

FIG. 3 shows a phase of the honing process in which the annular cutting group 330, for example during a downward movement from the bore inlet 314 in the direction of the bore exit, at the level of a transitional section 323 between the circular cylindrical first bore section 322 and the downward conical second bore section 324 located. The transition section usually has a slight rounding with a suitable transition radius, so it is not sharp-edged. An anticipatory part of the cutting material body 140 has already reached the conical bore section coming from the cylindrical bore section, in which the bore widens and the lateral surface of the bore is inclined or inclined relative to the bore axis. Here, an axially unequal load may result, which may lead to the formation of a tilting moment and possibly to a slight tilting of the cutting material carrier 150. The resilient intermediate layer 160 may compensate for a portion of this tilt by compressing the upper portion more than the lower end leading to the bore end. This can also be used during honing of the conical Hole section provide relatively uniformly distributed machining forces, so that the surface structure over the entire bore length, including both the cylindrical bore portion and the conical bore portion and the transition section can remain relatively uniform. Because of the elastically yielding intermediate layer, the cutting material bodies are tiltable with respect to the cutting material body carrier not only in the axial direction (about a tilting axis tangential to the honing tool), as shown schematically in FIG. A tilt in the circumferential direction is possible to a small extent. This tilting movement can take place, for example, about a substantially axis-parallel tilting axis. As a result, the cutting material bodies of the bore inner surface can follow even without constraining forces, even if the macroscopic shape of the bore inner surface in the machined portion deviates significantly from a rotationally symmetrical shape. For example, bore sections of oval shape or cloverleaf shape or out of roundness of higher orders or irregular non-rotationally symmetric shapes can be honed by virtue of the individual flexibility of the cutting bodies by honing to produce a relatively uniform over the entire circumference and / or the entire length of the bore Surface structure can be achieved. This is achieved, inter alia, by the fact that the cutting material bodies of the given surface shape can run to a certain extent due to the elastically yielding intermediate layer, so that pressure force peaks, as might occur with cutting bodies fixed rigidly to the cutting material body carrier, are alleviated or avoided. Thus, despite a non-circular bore and / or axial bore contour over the entire bore inner surface a relatively uniform depth of cut can be achieved. This can be favorable both for largely smooth end surfaces and for surfaces with a plateau structure. In this context, it is worth mentioning that the expansion force is usually a multiple of the "spring force" of the intermediate layer, resulting in a relatively uniform cutting depth even with "bumps", which are usually only radial deviations of a few μηη.

In the honing tool 100 with double widening, the three cutting-material-body carriers of a group are circumferentially offset from each other by 120 °. The cutting material body of a group are preferably identical to each other. The cutting material bodies of a first group preferably differ from the cutting bodies of a second group. For example, the cutting bodies of the two groups can have different widths and / or they can be mounted on the cutting material body carriers with different circumferential distances and / or different pitches. It is possible that the cutting bodies of one of the groups for coarser processing with coarser grain and the cutting material bodies of the other group are equipped for finer processing with finer grain. It is also possible that not all of the cutting material body of an annular cutting group are fixed by means of an elastically resilient intermediate layer on the associated Schneidstoffkörper carriers. It may be, for example, that in a first group the cutting material body sit directly on the cutting material body carrier without the interposition of an elastic intermediate layer and are thus rigidly connected to it, while in the other group the cutting material individually compliant via an elastic intermediate layer on the cutting material body carrier are attached. For example, a first group may be provided which is intended for contour honing and has cutting edges connected rigidly to the cutting material body carriers, while the second group is provided for a subsequent finish honing process and is equipped with cutting material bodies which resiliently fix relative to the cutting material body carrier are. In another process chain, it is also possible to design a first group for a Zwischenhonprozess and the second group for the subsequent finished honing process, the cutting material body of both cutting groups are resiliently mounted on the associated Schneidstoffkörper carriers.

A honing tool 400 according to another embodiment will be explained with reference to FIG. 4. Fig. 4 shows the honing tool in an axial view from the spindle end remote. The honing tool has a single annular cutting group 430 which is disposed at the distal end portion of the tool body and a total of eight Schneidstoffkörper- support 450-1 to 450-8, which are deliverable radially to the tool axis 412 and each cover a circumferential angle range, which is greater than that axial length of the cutting material body or the cutting group is. Each of the cutting body carriers covers a circumference of about 40 °.

The cutting body carriers 450-1 and 450-2, together with the respective diametrally opposed cutting material body supports 450-5 and 450-6, belong to a first group of cutting material body carriers carrying relatively narrow cutting bars 440-1. The cutting material body supports 450-3, 450-4, 450-7 and 450-8 belong to a second group of cutting material body carriers whose cutting material body carriers each carry cutting edges 440-2 with a somewhat larger circumferential width. Non-cutting guide strips 415-1, etc. are attached between immediately adjacent pairs of cutting material body supports. Thus, immediately adjacent cutting material body carriers of the same group without intermediate guide strip in the circumferential direction next to each other, while between adjacent cutting material body carriers of different groups each one of the guide rails is arranged. The four cutting material body carriers of a group can each be radially delivered together and withdrawn, the two groups can be fed radially independently and withdrawn. It is thus possible to carry out a first, first honing operation with a first group, then to withdraw this group, to deliver the other group radially and then to carry out a downstream second honing operation with the cutting material bodies of the second group.

Another possibility for fastening individual strip-form cutting material bodies 540-1, etc., to a common cutting material body carrier 552 will be explained with reference to FIG. In this embodiment, a thin flexible plate 560 'made of elastomer (thickness about 1 mm) on the cylindrically curved outer side 554 of the metallic Schneidstoffkörper- carrier 552 vulcanized or glued. The individual cutting bodies 540-1 etc. are then glued to the outside of the elastomer layer. For this purpose, the outside 562 is first sandblasted, sanded or otherwise reduced to an average surface roughness of e.g. 20-40 μηη roughened. In addition, the rear side 542 of the cutting material body to be connected to the elastic intermediate layer is also roughened by sandblasting, grinding or otherwise, with typical roughness depths are usually in the range between 10 μηη and 20 μηη. The adhesive for the adhesive layer 565 can be applied on one side or on both sides before the respective cutting material body is pressed at the intended location on the outside of the elastomer plate until the adhesive has cured. The roughening of the adhesive layer 565 adjacent surfaces of the cutting material body and the elastomeric plate, the permanent adhesive strength can be significantly increased compared to non-roughened surfaces. This flexible plate 560 'forms an elastomeric layer that, together with (at least) one adjacent adhesive layer 565, forms a multilayer interlayer 560. The intermediate layer may have spatially homogeneous elasticity properties in the region between the cutting material body carrier and the cutting material body carried by the intermediate layer, which may be achieved, for example, by an intermediate layer of homogeneous elastic material completely filling the intermediate space. It is also possible for the intermediate layer to be designed such that it is spatially inhomogeneous in the region which carries a cutting material body and / or has inhomogeneous elasticity properties, ie elasticity properties that extend beyond the area of the site used to support a cutting material body to change location.

For exemplary explanation, FIGS. 6A, 6B and FIGS. 7 to 9 show some variants of exemplary embodiments with spatially, in particular laterally inhomogeneous intermediate layers. The intermediate layer 660, which is shown in vertical section in FIG. 6A and in plan view in FIG. 6B, was made from a flat, plane-parallel piece of elastomeric material into which blind holes 662 of different depth and / or size are provided, according to a predetermined distribution, from that for supporting a cutting material body 640 provided side, for example by mechanical drilling or laser machining. The holes can be evenly or irregularly distributed. They can also all have the same depth and / or same diameter. The cutting material body 640 is adhered to the multiple openwork free surface and closes the holes to the outside, so that the intermediate layer is protected circumferentially and from above and below against penetration of honing sludge or the like into the cavities.

FIG. 7 shows a plan view of a flat intermediate layer 760 made of elastomeric material, which is designed in the manner of a circumferentially closed frame with a single long inner cavity 762. After sticking the associated Schneidstoffkörpers and this cavity is completed on all sides. In the variant of the intermediate layer 860 in FIG. 8, obliquely extending slits 862 are introduced into the original flat material made of elastomer, which, like the bores in FIG. 6A, are circumferentially closed after adhesive bonding of the supported cutting body and are thus protected against penetration of honing slurry etc.

These are some examples of intermediate layers which have more or less large cavities of different and / or identical shape and / or size and which thereby tend to be more elastically resilient than the corresponding elastomeric solid material into which the cavities (bores, slots or the like) are introduced were. It is also possible intermediate layers of closed-porous elastomeric material, ie such elastomeric material, in which already after manufacturing all sides enclosed cavities (closed pores) are present.

In one embodiment of FIG. 9, the elastomeric material of the intermediate layer 960 completely fills the gap between the cutting material body carrier and the cutting material body 940. The elastomeric material is laterally structured and has a succession of adjacent strips 964-1 of a relatively softer elastomeric material and 964-2 of relatively harder elastomeric material.

The examples of FIGS. 6 to 9 illustrate that there are different ways of precisely matching the elasticity properties of the intermediate layer with simple means intended use of the honing tool designed therewith adapt. In the examples, a layer of elastomer material laterally structured by means of cavities and / or uneven material distribution is provided for this purpose. The layer thicknesses, which determine the distance between cutting material body carrier and cutting material body in the unloaded state, are usually in the range of 0.1 to 2 mm, in particular in the range of 0.5 to 1 .5 mm.

The advantages of honing tools according to the invention can be achieved independently of the type of pre-machining of the hole to be honed. Before starting the honing operation using the honing tool, a bore shape significantly different from the circular cylindrical shape can be produced by fine boring and / or honing. By means of the honing operation, the surface texture desired on the bore inner surface can then be substantially performed without changing the predetermined macro-shape of the bore due to the use of a honing tool with individually elastically compliant cutting bodies.

Claims

claims

Honing tool (100, 400) for machining an inner surface of a bore (320) in a workpiece (300) by means of at least one honing operation, in particular for

Honing of cylinder surfaces in the production of cylinder blocks or

Cylinder liners for reciprocating engines, comprising:

a tool body (110) defining a tool axis (1 12, 412);

an expandable cutting group (130, 430) attached to the tool body and having a plurality of radially deliverable cutting body carriers (150-1, 150-2, 450-1, 450-2), which each cover a circumferential angle range and are cut by means of a cutting group Delivery system radially to the tool axis (1 12, 412) are deliverable, wherein

each cutting-material-body carrier carries on its radial outer side (154, 454) a plurality of narrow cutting-material bodies (140-1, 140-2, 140-3) which serve as circumferentially narrow cutting-material strips (140-1, 140-2, 140-3, 440-1, 440-2) are formed whose width (BS) in the circumferential direction is small compared to the axial length (LS) of the cutting material strips, wherein the cutting material bodies are arranged at a mutual distance from each other,

characterized in that

in an intermediate space between a cutting material body and the cutting material body carrying Schneidstoffkörper carrier (150-1, 150-2, 450-1, 450-2) an elastically resilient intermediate layer (160, 560, 660, 760, 860, 960) is arranged is, which fills the gap between the cutting material body and the cutting material body carrier.

Honing tool according to claim 1, characterized in that the intermediate layer (160, 560, 660, 760, 860, 960) has a layer thickness (SD) which is in the range of 0.1 mm to 2 mm, in particular in the range of 0.5 mm to 1, 5 mm.

Honing tool according to claim 1 or 2, characterized in that a Shore hardness of the intermediate layer (160, 560) is in the range of 70 Shore A to 95 Shore A.

Honing tool according to one of the preceding claims, characterized in that the intermediate layer (160, 560, 660, 760, 860, 960) comprises a layer of an elastomer, in particular of a rubber-elastic polyurethane elastomer. Honing tool according to one of the preceding claims, characterized in that the intermediate layer (160) is vulcanized directly onto a contact surface on the cutting material body (140-1, 140-2, 140-3) or the outer surface (154) of the cutting material body support member.

The honing tool according to any one of the preceding claims, characterized in that the intermediate layer (560) comprises a first layer and at least one second layer bonded thereto, wherein the first layer is a layer (560 ') of an elastomer and the second layer is one with the the first layer is a surface-bonded adhesive layer (565).

Honing tool according to one of the preceding claims, characterized in that the cutting group has an axial length (LS) measured in the axial direction, which is smaller than an effective outer diameter (AD) of the cutting group at fully retracted Schneidstoffkörpern.

Honing tool according to claim 7, characterized in that the honing tool has at least one of the following properties:

(i) the axial length (LS) of the cutting bodies is less than 40% of the effective outside diameter of the cutting group;

(ii) the axial length (LS) of the cutting material bodies is in the range of 5 mm to 40 mm;

(iii) the axial length (LS) of the cutting material bodies is less than 20% of the bore length of the bore;

(iv) the axial length (LS) of the cutting bodies is in the range of 20% to 50% of the bore diameter;

(v) An aspect ratio between the axial length (LS) and the width (BS) of the cutting bodies is in the range of 4: 1 to 20: 1.

Honing tool according to one of the preceding claims, characterized in that the cutting group (130, 430) comprises at least three cutter body support, which are arranged such that machining forces over the entire available by expansion effective outer diameter of the honing tool evenly distributed over the circumference of the cutting group , wherein the cutting group preferably, exactly four, exactly six or exactly eight cutting material body carrier of the same or different circumferential width. Honing tool according to one of the preceding claims, characterized in that the honing tool (100, 400) is designed as a double-widening honing tool, the cutting group (130, 430) comprising a first group of cutting-material body supports (450-1, 450-2, 450-5, 450-6) and a second group of cutting material body carriers (450-3, 450-4, 450-7, 450-8) deliverable independently of the first group.

Honing tool according to claim 10, characterized in that the cutting material bodies of the first group differ from the cutting bodies of the second group, preferably in that the cutting bodies of the two groups have different widths and / or with different circumferential distances and / or different pitch on the Schneidstoffkörper- Carriers are mounted and / or that the cutting material body of one of the groups for coarser processing with coarser grain and the cutting material body of the other group are equipped for finer processing with finer grain.

Honing tool according to claim 10 or 1 1, characterized in that in the first group, the cutting material without the interposition of an elastic intermediate layer attached directly to the associated Schneidstoffkörper carrier and are rigidly connected to the cutting material body carrier and in the second group, the cutting material body individually compliant over an elastic intermediate layer are mounted on the associated cutting material body carrier.

Finishing method for machining the inner surface of a bore in a workpiece, in particular for fine machining of cylinder surfaces in the manufacture of cylinder blocks or cylinder liners for reciprocating engines,

the finishing method comprising at least one honing operation in which an expandable honing tool moves up and down within the bore to produce a stroke in the axial direction of the bore and at the same time is rotated to produce a rotational movement superimposed on the lifting movement,

characterized in that

in the honing operation, a honing tool having the features of at least one of the preceding claims is used. Finishing method according to claim 13, characterized in that prior to the start of the honing operation by fine boring and / or honing a deviating from the circular cylindrical shape bore shape is generated and that a honing operation for generating the surface desired on the bore inner surface substantially without changing the macro-shape of the bore using the Honing tool is performed.

Finishing method according to claim 13 or 14, characterized in that a double widening honing tool is used in which a cutting group (130, 430) of the honing tool comprises a first group of cutting body carriers (450-1, 450-2, 450-5, 450 6) and a deliverable independent of the first group second group of Schneidstoffkörper- carriers (450-3, 450-4, 450-7, 450-8), wherein each of the cutting material body carriers of a group are delivered radially together and withdrawn , With the first group, an upstream first honing operation is performed, this group is then withdrawn, the other group is radially delivered and then with the cutting material bodies of the second group, a downstream second honing operation is performed.

Finishing method according to claim 13 or 14, characterized in that the first group rigidly connected to the cutting material body carriers cutting material body and the first honing operation is a Konturhon operation, and that the second group is equipped with cutting material bodies, which at the associated Schneidstoffkörper- Carriers are resiliently secured via an elastically resilient intermediate layer, wherein the second honing operation is a Nachlaufhon operation.