EP3164244A1

EP3164244A1 - Honing tool and honing method

Info

Publication number: EP3164244A1
Application number: EP15730796.8A
Authority: EP
Inventors: Fabio Antonio XAVIER; Florian KRANICHSFELD; Joachim Weiblen; Oliver Bachmann
Original assignee: Elgan Diamantwerkzeuge GmbH and Co KG
Current assignee: Elgan Diamantwerkzeuge GmbH and Co KG
Priority date: 2014-07-03
Filing date: 2015-06-23
Publication date: 2017-05-10
Anticipated expiration: 2035-06-23
Also published as: DE102014212941A1; EP3164244B1; HUE038938T2; WO2016001014A1

Abstract

A honing tool for machining an inner surface of a bore in a workpiece with the aid of at least one honing operation comprises a tool body (210) which defines a tool axis (212), an expandable annular cutting group (220) having a plurality of cutting material bodies distributed around the circumference of the tool body, the axial length of said cutting material bodies, measured in the axial direction, being less than an effective outside diameter of the cutting group with the cutting material bodies fully retracted, wherein the cutting material bodies are arranged in an end region, remote from the spindle, of the tool body and are infeedable radially with respect to the tool axis by means of a cutting group infeed system assigned to the cutting group; and an expandable guiding group (300) having a plurality of guiding strips (320) distributed around the circumference of the tool body, said guiding strips (320) being arranged on the tool body partially or fully between the annular cutting group (220) and a spindle-side coupling structure of the honing tool and being radially infeedable independently of the cutting material bodies by means of a guiding group infeed system. The honing tool can be used in particular for honing cylinder surfaces in the production of cylinder blocks or cylinder liners for reciprocating piston engines.

Description

Honing tool and honing method

AREA OF APPLICATION AND PRIOR ART

The invention relates to a honing tool according to the preamble of claim 1. Furthermore, the invention relates to a honing method according to the preamble of claim 10. A preferred application is the honing 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, a cross-cut pattern typical for honing is usually produced on the inner surface with intersecting machining marks, which are also referred to as "honing marks".

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 friction ratio of the piston group can be up to 35%, so that friction reduction in this area is desirable. Different approaches are used to reduce the mechanical losses of an actuator. These include the use of thermally-molded cylinder surfaces, the use of coated piston rings, the development of particularly optimized honing surfaces, etc.

A technology that is becoming increasingly important for the reduction of friction and wear is the avoidance or reduction of cylinder distortions or deformations of the engine block (cylinder crankcase) during assembly and / or operation. After conventional honing, a cylinder burr should typically have a bore shape that is as small as possible, e.g. a few micrometers, deviates from an ideal circular cylinder shape. During assembly or operation of the engine, however, it can lead to significant form errors, which can be up to several hundredths of a millimeter and reduce the performance of the engine. The causes of distortions or deformations are different. It may be static or quasi-static thermal and / or mechanical loads or dynamic loads. The construction and design of cylinder blocks also influence the tendency to deform. The sealing function of the piston ring package is typically degraded by such hard-to-control deformations, which can increase blow-by, oil consumption and also friction.

In order to reduce problems due to distortion during assembly or in certain operating states, it has been proposed for example in DE 28 10 322 C2 to deform the engine block for honing machining with the aid of a tensioning device in such a way that the later deformation is simulated by the cylinder head , In the clamped state, which corresponds to the state present after assembly later, the honing takes place to produce a circular cylindrical bore shape, which should then be set again after assembly.

Another technology that is intended to ensure or approximate the formation of an ideal shape after assembly or in the operating state of the engine by an inversion of the cylinder distortions (generation of a negative shape of the error) is the so-called Formhonen. In this case, a defined from the circular cylindrical shape bore shape is generated on the unstrained workpiece by honing, for example, a cloverleaf. Such bore shapes are usually asymmetrical, because the deformations of the cylinder block usually not symmetrical are. In the operating state, the most ideal circular cylindrical shape should result, so that the piston ring package can seal well over the entire circumference of the bore. Various variants of the mold honing are described, for example, in EP 1 790 435 B1 and in the prior art mentioned therein.

It has also been proposed to produce rotationally symmetrical bore shapes having bore portions of different diameters. The corresponding honing methods are sometimes referred to as "contour honing." For example, holes having a bottle shape, cone shape, or barrel shape can be machined and / or produced.

TASK AND SOLUTION

It is an object of the present invention to provide a generic honing tool and a honing method practicable using the honing tool which make it possible to produce reciprocating engines having improved friction loss, oil consumption and blow-by characteristics.

To solve this problem, the invention provides a honing tool having the features of claim 1. Furthermore, a honing method with the features of claim 10 is provided. Advantageous developments are specified in the dependent claims. The wording of all claims is incorporated herein by reference.

The honing tool has an annular cutting group, preferably exactly one single annular cutting group. An annular cutting group is characterized in comparison to conventional honing stones, inter alia, that in the covered by the annular cutting group substantially more contact surface between the cutting material body and bore inner surface exists as in a comparatively narrow axial portion of a conventional honing tool with relatively narrow honing stones. In some embodiments, more than 60% of the circumference of the annular cutting group is coated with cutting means, more preferably even more than 70% or more than 80% of the circumference of the cutting group.

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

It is preferably provided that the cutting material bodies are designed as wide in the circumferential direction and narrow in the axial direction Honsegmente, wherein measured in the axial direction axial length of the Honsegmente is smaller than a measured width in the circumferential direction. A hearing segment is usually rigid in itself, so that the entire hearing segment as a whole is moved during delivery. A hearing segment may define an uninterrupted cutting surface, but the cutting surface may possibly also be interrupted once or several times.

If at least three honing segments are provided, the machining forces can be distributed well and relatively evenly over the circumference of the cutting group over the entire effective outer diameter of the honing tool available through expansion. For example, in the cutting group exactly three, exactly four, exactly five or exactly six honing segments of the same or different circumferential width can be provided. Although more than six honing segments 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 only has two honing segments.

The axially narrow design of the cutting group, so its relative to the outer diameter short axial extent, can also help that at relatively low pressure forces large cutting performance can be achieved and that the paths for the removal of abraded material, ie from abrasion, are relatively short. Thereby clogging of the abrasive cutting surfaces of the cutting body can be avoided by abrasion and the cutting body remain permanently schneidfreudig. Due to the short design, a better cooling lubricant supply than with longer honing stones is possible, which in turn creates the opportunity to operate the honing tool for material removal at relatively high speeds, so that more removal can be achieved at lower cutting forces.

The honing tool is preferably designed such that the cutting material bodies can be delivered radially, so that the cutting material bodies are delivered radially (perpendicular to the tool axis), for example, during expansion of the cutting group. Due to the radial Zustellbar- speed, ie a displacement of the Honsegmente in the radial direction during the delivery, it can be achieved that the engagement conditions between cutting material body and bore inner surface remain practically constant. By avoiding cutting material body tilting during rend the radial feed uneven removal in the bore can be avoided.

In some embodiments, the cutting material bodies are elastically yielded with respect to the tool body. This can possibly improve the ability to trace the contour during axial movement. For example, spring elements (e.g., leaf springs, spiral compression springs of the like) may be interposed between the support members and the cutting material bodies. It is also possible to make the support elements elastically yielding, e.g. in that weakenings of the carrier material cross-section in the form of slots or the like are constructively provided at suitable locations.

The considerable advantages of the axially narrow shape of the annular cutting group can be used particularly well when the honing tool is designed so that, if necessary, the risk of tilting of the honing tool in the bore can be counteracted. For this purpose, the honing tool has an expandable guide group with a plurality of circumferentially distributed around the tool body guide rails - viewed in the axial direction - partially or completely disposed between the annular cutting group and a spindle-side coupling structure of the honing tool on the tool body and by means of a Führungsgruppen delivery system regardless of the cutting material radially are deliverable. By means of the deliverable if necessary guide rails, the honing tool can be supported within the bore in a suitable circular cylindrical bore portion so that the axial movement of the honing tool is guided within the bore.

Preferably, an axial length of the guide rails is more than twice as large as the axial length of the cutting group. In most cases, it is favorable if the axial length of the guide strips is at least four times as large as the axial length of the cutting group. In particular, an aspect ratio between the axial length of the guide rails and the axial length of the cutting group may be in the range of 5 to 20. A large guide length improves the axial stroke guiding properties and provides relatively low surface pressure in the area of the guide rails so that the bore surface can be spared.

The guide rails can be arranged at an axial distance from the cutting group or, viewed in the axial direction, connect to it. Then, the cutting region defined by the cutting group and the guide region defined by the guide strips are separated from each other in the axial direction. It is also possible that the guide rails protrude with a spindle distant portion in the axial region of the annular cutting group and there seen with this section in the circumferential direction between the cutting material bodies of the annular Cutting group are arranged. In this case, the guide area and the cutting area overlap, if necessary so far that the cutting group lies completely within the guide area.

To avoid contact pressure peaks, it is preferably provided that the guide strips have a width of at least 3 mm in the circumferential direction. The circumferential width may e.g. lie between 3 mm and 20 mm and / or in the range of 10% to 40% of the effective circumference in the region of the guide rails, possibly even less than 10% of this circumference.

The number of guide bars can be adapted to the processing task; it can be even or odd. Preferably, three, four, five or six guide rails are provided, which are preferably distributed uniformly around the circumference in order to achieve all-round uniform guidance.

Although the outside of the guide rails e.g. with fine-grained cutting grains, e.g. Diamond cutting, can be occupied, it is preferably provided that the guide rails are formed as non-cutting guide rails. In this case, they can not change the shape or the diameter despite contact with the bore inner surface and the surface structure can be largely retained. In particular, when the guide strips at least in the region of an outer surface to be turned on the inside of the bore consist of a material selected from the group: polycrystalline diamond (PKO), monocrystalline diamond (MKO), silicon-infiltrated diamond (SCO), hard metal and hard plastic , a bore-friendly guidance with a very long service life is possible.

The honing tool can be used for different honing processes, also for machining circular cylindrical holes. In a variant of a honing process, a bore shape deviating from the circular cylindrical shape is produced, which has a first bore-cylindrical first bore portion adjacent to a bore entry and a second bore portion remote from the bore entry and at least partially having a second diameter larger than the first bore Diameter is. The bore thus widens in the direction of the bore end lying opposite the inlet side and has a somewhat narrower "neck." The (larger in diameter) second bore section can likewise be circular-cylindrical and coaxial with the first bore section, so that the bore as a whole is rotationally symmetrical Between the first and the second bore portion may be a transition portion with a continuous transition from the first to the second diameter, so that a bottle shape results. Other contours are possible, such as a cone shape in the second bore section.

Here, the honing tool can be used with particular advantage by machining the second bore section by means of the annular cutting group in at least one processing phase and at the same time the guide rails are applied to the inner surface of the bore in the first bore section such that an axial movement of the honing tool by the guide rails in the first hole section is guided secured against tilting. Despite the small axial dimensions of the Schneidstöffkörper and / or any existing lability of the geometry of the components to be honed thereby a pure axial movement is ensured (without tilting parts), which systematically surfaces can be achieved with high quality. The honing tool can be used permanently or in phases even with retracted guide rails, so that only the cutting material body of the annular cutting group are in engagement or in contact with the bore inner wall.

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:

1 shows a schematic longitudinal section through such a bottle-shaped bore in a workpiece in the form of an engine block for an internal combustion engine.

Fig. 2 shows an embodiment of a honing tool, wherein Fig. 2A shows a longitudinal section and Fig. 2B shows an axial view of the honing tool from the side of the spindle-side coupling structure;

3 shows a processing situation in which a bottle-shaped bore is machined by means of a honing tool according to an embodiment;

Fig. 4 shows another embodiment of a honing tool, wherein Fig. 4A shows a longitudinal section and Fig. 4B shows an axial view of the honing tool from the side of the spindle-side coupling structure. DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following, embodiments of honing methods and honing tools are described that can be used in the context of embodiments of the invention in the material-removing machining of workpieces having one or more holes, which should have the macro-shape of a bottle in the finished state.

Fig. 1 shows a schematic longitudinal section through such a bottle-shaped bore 1 10 in a workpiece 100 in the form of an engine block (cylinder crankcase) for an internal combustion engine. The bore is rotationally symmetrical with respect to its bore axis 1 12 and extends over a bore length L from a bore entry 1 14 facing the cylinder head in the installed state to the bore exit 16 at the opposite end. The bore may be subdivided into three contiguous sections of different function, which may be slidable, i. without formation of steps or edges, merge into each other.

A first bore portion 120 at the entrance end has a first diameter D1 and a first length L1. At the opposite exit-side end extends over a second length L2, a second bore portion 130 whose inner diameter (second diameter) D2 is greater than the first diameter D1. Between the first bore section 120 and the second bore section 130 there is a partially conical transition section 140 in which there is a continuous transition from the first diameter to the second diameter. Between the central, substantially conical part of the transition section and the first bore section, a first radius R1 is formed, while a second radius R2 is formed between the transition section and the second bore section. The radii R1 and R2 may be substantially equal, but it is also possible that the first radius is smaller or larger than the second radius.

For example, in typical bore geometries, the first length L1 may be between 10% and 60% of the bore length L. The second length L2 is typically greater than the first length and is often between 30% and 80% of the bore length L. The transition section is normally relatively short to the adjacent bore sections. Typical third lengths L3 may range from 5% to 20% of the bore length L. Even deviations from these geometrical conditions are possible.

The difference in diameter between the first diameter D1 and the second diameter D2 is well outside the tolerances typical for the honing processing, which for a cylindrical shape in the order of a maximum of 10 μηι (based on the diameter) lie. With an absolute value of the inner diameter in the order of between 70 mm and 150 mm, the difference in diameter may for example be between 20 μηη and 90 μηη.

The radii R1, R2, the lengths of the outer bore portions and the transition portion, and the tangent angle T between the bore axis and a tangent to the transition portion may be optimized to provide low blow-by, low oil consumption, and low wear in typical engine operating conditions Give piston rings.

The bottle shape of the bore causes the bore in the near-entry region is relatively narrow, so that the piston rings of the piston running in the bore are pressed under high hoop stress to the bore inner surface 1 18. As a result, where the combustion takes place mainly and high pressures occur, a reliable seal is achieved and the oil film is stripped in the downstroke. The piston accelerated by the combustion then moves in the direction of the bore exit, whereby the piston rings first pass (partially) through the transition section with the continuously enlarged inner diameter and then the second bore section. In the transition section, the piston rings can gradually relax, with the seal remaining sufficient because the pressure difference across the piston rings decreases. At the beginning of the second bore section, the ring package reaches its lowest tension, so that friction losses are reduced by reduced ring tension, especially in the range of maximum piston speed. During the upward stroke, the hoop tension then increases again as soon as the piston rings reach the exit-side radius of the transition section and pass through it in the direction of the first bore section.

A finishing process that can economically produce such a well in both high quality with respect to the macro-shape (bottle shape) and the surface structure of the tribologically stressed bore inner surface includes in embodiments of the invention at least one honing operation using a honing tool of particular construction, which is incorporated herein by reference An embodiment is shown in Fig. 2. Here, Fig. 2A shows a longitudinal section and Fig. 2B shows an axial view of the honing tool from the side of the spindle-side coupling structure (not shown in the figure) ,

The honing tool has a cutting group attached annularly to the tool body with cutting material bodies distributed around the circumference of the tool body, which are delivered or returned in the radial direction by means of an associated cutting material body feed system. can be withdrawn. The cutting material bodies are designed as Honsegmente whose width in the circumferential direction is significantly greater than their length in the axial direction. The cutting material bodies responsible for material removal on the workpiece are concentrated in an axially relatively narrow zone (a ring of the cutting group) and occupy a relatively large portion of the circumference of the honing tool. As a result, bore shapes can be produced with a relatively high material removal rate, in which bore sections of different diameters adjoin one another in the axial direction.

The honing tool 200 has a single annular cutting group 220 and a guide group 300 disposed between it and the spindle-side coupling structure. The honing tool 200 has a tool body 210 defining a tool axis 212 which is also the axis of rotation of the honing tool during honing. At the spindle-side end of the honing tool (in Fig. 2A above) is a coupling structure not shown for coupling the honing tool to a drive rod of a honing machine or other machine tool, which has a work spindle, which is both about the spindle axis rotatable and parallel to the spindle axis oscillating is movable back and forth.

The honing tool is hinged to the honing spindle to allow limited movement of the honing tool relative to the honing spindle. For this purpose, a multiaxial joint is formed at the spindle-side end of the honing tool, e.g. a gimbal joint or a ball joint (see Fig. 3 or 4).

At the spindle end facing away from the tool body (in Fig. 2A below) is the annular cutting group 220, which has several (in the example, three) evenly distributed over the circumference of the tool body Schneidstoffkörper 220-1, 220-2, 220-3, which by means of a Cutting material body delivery system radially to the tool axis 212 can be delivered to the outside to press the abrasive outer sides of the Schneidstoffköpers with a defined pressure force or contact force against the inner surface of a bore to be machined. Each of the three curved cutting material body is designed as a very wide in the circumferential direction, in contrast, in the axial direction against narrow Honsegment which covers a circumferential angle range between 90 ° and 1 10 °. The honing segments are decoupled from the tool body and displaceable radially relative to the tool axis 212. The ring formed by the hearing segments closes on the side facing away from the spindle almost flush or flush with the tool body. The ring sits completely within the spindle facing away quarter of the tool body at the spindle end facing away from the ring tool. The axial length of the cutting material body defines here the axial length of the cutting area. The axial length LHS of the heel segments is less than 20%, in particular less than 10% of the bore length. The honing segments are about 5 mm to 30 mm, in particular about 10 mm high (in the axial direction), which in the example between 5% and 30%, in particular between 10% and 20% of the effective outer diameter of the cutting group (with completely retracted cutting bodies) equivalent. The axial length LHS corresponds here simultaneously to the axial length of the entire cutting region of the honing tool.

Each cutting material body is fixed to an outside of an associated support bar 224-1, 224-2 made of steel by soldering. Alternatively, the cutting material body can also be attached by gluing or by screws, whereby an easier replacement is possible. Each support bar has on its inner side an inclined surface which cooperates with a conical outer surface of an axially displaceable, tubular or inside hollow feed cone 232 in such a way that the support bars are delivered with the cutting material carried therefrom radially outward when the Zustellkonus means of a machine side Zustellvorrich- against the force of (not shown) return springs in the direction of the spindle facing away end of the ring tool is pressed. In the case of an opposing feed movement, the carrying strips with the honing segments are brought back radially inward with the help of circulating return springs. The radial position of the cutting material body is thereby controlled without play on the axial position of the Zustellkonus 232.

The guide assembly 300 has three identical guide rails 320-1, 320-2, 320-3 distributed evenly around the circumference of the tool body with a circumferential angular separation of 120 °. Each guide rail sits at a small axial distance in the middle above an underlying Honsegments. However, the guide rails can also be located elsewhere, e.g. sit above the transitions between adjacent hearing segments. It can also be provided more than three guide rails, for example, four or six. The axial length of the guide rails defined here the axial length of the guide portion, which is here at an axial distance from the cutting area and does not overlap with this.

Another variant, in addition to radially deliverable guide rails also have fixed measuring strips that carry components of a diameter measuring system, e.g. Measuring nozzles of a pneumatic measuring system (see Fig. 4).

The guide strips of the radially expandable guide group 300 can be delivered radially independently of the cutting material bodies of the radially expandable annular cutting group. For this purpose, each guide rail is fastened on a guide rail support body 324-2, etc., which at its radial inner side has two obliquely arranged one above the other at an axial distance. has surfaces which cooperate with corresponding inclined surfaces of an axially displaceable feed cone 332 of a guide group feed system in the manner of a wedge drive, so that an axial displacement of the feed cone 332 to the distal end causes a radial displacement of the guide rails to the outside (and vice versa). The feed cone 332 of the guide group feed system sits radially backlash-free, but axially movable in the interior of the tubular delivery cone 232 of the cutting group feed system.

The guide rails can be withdrawn radially inward to the extent that they are radially surmounted by the cutting bodies, so that they are e.g. when working a circular cylindrical bore with distance to the working bore inner wall and do not touch.

The guide rails should have exclusively leading function in this embodiment and cause no material removal. They are therefore made of a hard metal and have on their the bore inside facing outer surface on a smooth polished surface, which is slightly curved cylindrically, to produce the largest possible contact when pressed against the bore inner surface. In other variants, the guide rails are made at least in the area of the outside of PCD, a ceramic or a hard plastic. The circumferential width of the guide rails can be many times less than the circumferential width of the cutting material body, but should not fall below 3 mm to 10 mm usually so that the radial pressure to the outside surface pressure on the bore inner surface remains as low as possible.

The honing tool can be operated with any processing machine which has two separately controllable feed drives for the two delivery systems. Honing machines for honing tools with double widening are known per se and can be used for this purpose.

There are various ways of making contour bores (e.g., bottle-shaped bores or conical-section bores or cone-shaped bores) having a desired surface texture of the bore inner surface using one or more of the honing tools of the type described in this application. A variant will be explained in more detail with reference to FIG.

In the variant of the method, a conventional honing tool with axially relatively long, narrow honing stones was first used in order to produce a honed bore with a circular cylindrical form starting from, for example, a pre-machined hole by precision boring. The axial strip length was about 1/2 to 2/3 of the total bore length. At a first peration (pre-honing) was carried out with diamond strips of the type D107, a subsequent Zwischenhonoperation was carried out with fine grain size (grain size D54). As a result, a substantially circular-cylindrical bore shape with little deviation from the ideal shape and with a relatively smooth surface (R _z <8 μm) was produced. The inlet-side and outlet-side honing overflow was about 1/3 of the strip length, similar to conventional methods. The honing overflow can be shortened when machining V or monoblock motors.

In a variant of the method, in the contour honing operation, e.g. used in the production of a bottle-shaped bore shape from a previously still circular cylindrical bore shape, an expandable ring tool WZ with guide strips FL. For this purpose, it is provided that the control of the expansion system for the radial delivery of Honsegmente (ie the cutting group delivery system) is coupled to the control for the stroke position so that the ring tool can generate the transition section with the changing diameter accurately and in the cylindrical first and second bore section operates with a suitable contact force. The contour honing operation may be provided as a second honing operation immediately after prehone.

The Hubabhängige control of expansion then takes place so that the Honsegmente HS of the cutting group SG delivered in a downward stroke corresponding to the bottle shape in response to the stroke position and force controlled radially outwards and in an upstroke according to the bottle shape as a function of the stroke position in the Transition section radially retracted again. Thus, from the beginning, a smooth contour in the transition section can be achieved.

On the honing machine, this can be achieved by inputting certain stroke ranges corresponding to the first to third bore sections in the control program, so that the cutting group expands by way and away widening during the downward stroke from the end of the first bore section. On the upstroke, the widening of the cutting group then travels back from the end of the third bore section to generate the desired programmed bottle-shaped cylinder.

Due to the articulated coupling of the tool body WK via a joint G to the work spindle, it can not always be ruled out that, especially at the transition of machining from a narrower bore area to another bore area, the honing tool tends, due to the component design, easily from the work spindle herauszukippen coaxial position. Any tilting tendency is the honing tool thereby Prevents that compared to the cutting group axially very long guide strips FL by means of the guide bar delivery system at any time with a suitable application force to the inside of the hole in the near-first bore portion BA1 are created. The engagement length can essentially correspond to that length over which the first bore section BA1 has a uniform diameter or circular cylindrical shape. As soon as, on a downward stroke, the annular cutting group moves from the first bore section into the underlying, widening transition area and is gradually delivered radially outward, the guide rails FL within the first bore section BA1 guide the axial movement by producing, without material removal, along the bore inside. The guide rails FL are dimensioned such that they are also in engagement with the bore over the entire length of the first bore section BA1, when the annular cutting group SG has arrived at the entry-distant bore bottom or at the entry-distant reversal point. The guide rails should therefore be longer than the axial length of the larger diameter second bore portion BA2. The guide is maintained even during the upward movement of the honing tool.

Referring to Fig. 4, an embodiment of a honing tool 400 is explained, with which a workpiece 600 (eg cylinder liner) is processed, which has a rotationally symmetrical bore 615, which has a circular cylindrical first bore portion 620 at the hole entrance, which is slightly below the center of the bore in a conical second section 630 merges, in which the diameter of the bore to the entry-distal end is continuously expanding. 4B shows an axial plan view of the processing situation, FIG. 4A a longitudinal section along the line A-A in FIG. 4B.

The honing tool has a tool body 410 which is coupled via a ball joint 450 to a spindle-side coupling structure 460 which serves the tool connection to the work spindle. The honing tool thus has an integrated joint. The tool body and the components carried thereby are limited by the work spindle in several axes movable.

The tool body carries at the distal end of the spindle a single annular cutting group 420, which can be seen only in the plan view Fig. 4B. The axial dimensions are similar to those of the embodiment of FIG. 2. More than 30% to 50% of the circumference of the annular cutting group is occupied by cutting means. The axial length of the cutting material body is less than 30% of the effective outer diameter of the cutting group and / or in the range of 5 mm to 30 mm and / or less than 20% of the bore length of the bore. The annular cutting group has here six radially deliverable Honsegmente 420-1 etc., which can be delivered radially together analogous to the embodiment of FIG. 2 via a cutting group delivery system. The cutting group has six identical honing segments, each covering a circumferential angular range of approximately 45 °. The inherently rigid Honsegmente carry on their outer sides each cutting material body with axial longitudinal grooves, so that the radially extending cutting surface is interrupted in the circumferential direction many times. It is also possible to fasten relatively narrow honing stones to the outer side of the rigid cutting-material-body carrier element that is curved in the circumferential direction in the circumferential direction, which have a circumferential distance from each other, so that groove-like intermediate spaces are formed between the honing stones. By running in the axial direction (or at an acute angle) grooves or gaps a very efficient removal of abrasion by means of the cooling lubricant is possible.

Furthermore, a radially expandable guide group 500 with four circumferentially distributed around the circumference of the tool body, radially deliverable guide rails 520 is provided on the tool body, which can be delivered radially independently of the cutting material bodies using a guide group delivery system. In order to ensure a radial delivery without risk of tilting in spite of the large axial length of the guide rails, three axially spaced sections are provided with inclined surfaces in this embodiment on the inner sides of the guide rail support, which cooperate with three axially spaced cone sections of the Zustollkonus 532.

The guide rails are arranged in pairs diametrically opposite each other in two axial planes offset by 60 °. Between those circumferentially adjacent guide rails, which enclose a circumferential angle of about 120 °, undetectable, so permanently mounted measuring strips 550 are attached to the tool body. Each of the measuring strips carries a measuring nozzle of a pneumatic diameter measuring system of the honing tool. Since such measuring systems are known per se, a detailed description is omitted here.

Unlike in the embodiment of FIG. 2, the axially elongate guide strips 520-1, 520-2, etc., extend into the axial area of the annular cutting group 420, so that the spindle distal sections of the guide strips are arranged between adjacent cutting bodies resp are. The axially relatively long guide region covered by the guide strips here completely overlaps with the axially relatively short cutting region defined by the annular cutting group. However, a larger length portion of the guide rails, eg more than 50% or more than 60% or more than 70% of the total length of the guide rails, extends in the range between the annular cutting group and the spindle-side coupling structure of the honing tool. As a result, the honing tool can also be guided by means of the guide rails in the first bore section 620 close to the inlet, when the spindle-distal cutting group processes the bore in the region of the conical bore section 630. On the other hand, it is possible by the overlap of the guide area and cutting area, to guide the honing tool in the first bore section, when the cutting group machined the inlet end or even partially protrudes into the area outside of the bore at honing overflow at the upper reversal point.

Honing tools or ring tools of the type described here can be used not only for the production or processing of bottle-shaped holes, but can bring significant benefits without modification in the processing of holes with different geometry.

It is e.g. possible to produce and / or work with a ring tool with guide rails a Bohrungsform having a frusto-conical bore portion (cone section), which merges relatively abrupt or with transition radius in an adjacent cylindrical bore portion, without another hole section adjoins. Thereby, e.g. a bore of funnel shape having an input cylindrical first bore portion having a first diameter which increases conically in an adjacent second bore portion to the bore bottom to a maximum diameter (see Fig. 4A). The difference in diameter between the cylindrical first bore portion and the maximum diameter in the conical second bore portion may be less than 200 μηη and e.g. between about 20 μηη and about 90 μηη lie. The axial length of the cylindrical first bore portion may be e.g. between 20% and 80% of the total bore length.

Furthermore, it is possible to use a ring tool with guide rails in a bore a barrel-shaped bore portion, i. to create a bulge in an otherwise largely cylindrical bore. The bulge may e.g. in the middle or close to one of the bore ends. It is also possible to machine holes with a circular cylindrical shape by means of such honing tools.

Claims

claims

1. Honing tool for machining an inner surface of a bore in a workpiece by means of at least one honing operation, in particular for honing cylinder running surfaces in the manufacture of cylinder blocks or cylinder liners for reciprocating engines, comprising:

a tool body (210) defining a tool axis (212);

an expandable annular cutting group (220, 420, SG) with a plurality of circumferentially distributed around the circumference of the tool body, whose axially measured axial length is smaller than an effective outer diameter of the cutting group with fully retracted cutting material bodies, the cutting material body in a distal end of the spindle Tool body arranged and by means of one of the cutting group associated cutting group delivery system are deliverable radially to the tool axis; and

an expandable guide assembly (300, 500) having a plurality of guide rails (320, 520, FL) distributed about the circumference of the tool body partially or entirely between the annular cutting assembly (220, 420, SG) and a spindle-side coupling structure (460) of the honing tool Tool body arranged and bodies are radially deliverable by means of a guide group delivery system regardless of the cutting material.

2. Honing tool according to claim 1, characterized in that the honing tool has at least one of the following properties:

(i) at the annular cutting group (220) more than 60% of the circumference is occupied by cutting means, in particular more than 70% or more than 80% of the circumference of the cutting group;

(ii) the axial length (LHS) of the cutting material bodies is less than 30% of the effective outside diameter of the cutting group, in particular between 10% and 20% of this outside diameter;

(iii) the axial length (LHS) of the cutting bodies is in the range of 5 mm to 30 mm;

(iv) the axial length (LHS) of the cutting bodies is less than 20% of the bore length of the bore.

3. honing tool according to claim 1 or 2, characterized in that the cutting material body as wide in the circumferential direction and narrow in the axial direction honing segment (220-1, 220-2, 220-3) are designed, wherein the axial length of the Honsegmente is smaller than a measured width in the circumferential direction.

4. Honing tool according to one of the preceding claims, characterized in that the cutting group (220) has at least three Honsegmente (220-1, 220-2, 220-3), wherein preferably three, four, five or six Honsegmente same or different circumferential width are provided.

5. honing tool according to one of the preceding claims, characterized in that an axial length of the guide strips (320, FL) is more than twice as large as the axial length of the cutting group, wherein preferably a length ratio between the axial length of the guide rails and the axial length the cutting group is in the range of 5 to 20.

6. honing tool according to one of the preceding claims, characterized in that the guide strips (320, 520, FL) in the circumferential direction have a width of at least 3 mm.

7. honing tool according to one of the preceding claims, characterized in that three, four, five or six guide rails (320, 520, FL) are provided.

8. honing tool according to one of the preceding claims, characterized in that the guide strips (320, 520, FL) are formed as non-cutting guide rails.

9. honing tool according to one of the preceding claims, characterized in that the guide strips at least in the region of the inside of the bore zuwendenenden outer surface (322-2) consist of a material which is selected from the group: polycrystalline diamond, monocrystalline diamond, silicon infiltrated diamond , Carbide and hard plastic.

10. Honing method for machining the inner surface of a bore in a workpiece by means of at least one honing operation, in particular for honing cylinder surfaces in the manufacture of cylinder blocks or cylinder liners for reciprocating engines, wherein, during a honing operation, an expandable honing tool is moved up and down within the bore to produce a stroke movement in the axial direction of the bore and at the same time rotated to produce a rotational movement superimposed on the lifting movement,

characterized in that

a honing tool (200, 400, WZ) having the features of at least one of the preceding claims is used.

1 1. Honing method according to claim 10, characterized in that a different from the circular cylindrical shape bore shape is produced, which subsequent to a hole entry a circular cylindrical first bore portion (120, 620, BA1) with a first diameter (D1) and remote from the bore entry a second bore portion ( 130, 630, BA2), which at least in sections has a second diameter (D2) which is greater than the first diameter.

The honing method of claim 1 1, characterized in that the second bore portion (130) is circular cylindrical and between the first and second bore portions is a transition portion (140) having a continuous transition from the first diameter to the second diameter.

13. honing method according to claim 1 1 or 12, characterized in that in at least one processing phase, the second bore portion (BA2) by means of the annular cutting group (SG) is processed and at the same time the guide strips (FL) to the inner surface of the bore in the first bore portion (BA1 ) are applied so that an axial movement of the honing tool (WZ) is guided by the guide rails in the first bore portion (BA1).