DE102010010901B4 - Method and apparatus for fine machining a crankshaft bearing bore - Google Patents

Method and apparatus for fine machining a crankshaft bearing bore Download PDF

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Publication number
DE102010010901B4
DE102010010901B4 DE102010010901.0A DE102010010901A DE102010010901B4 DE 102010010901 B4 DE102010010901 B4 DE 102010010901B4 DE 102010010901 A DE102010010901 A DE 102010010901A DE 102010010901 B4 DE102010010901 B4 DE 102010010901B4
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Prior art keywords
honing
bore
tool
bearing
spindle
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DE102010010901A1 (en
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Bernd Nagel
Martin Mayer
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Nagel Maschinen und Werkzeugfabrik GmbH
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Nagel Maschinen und Werkzeugfabrik GmbH
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B24GRINDING; POLISHING
    • B24BMACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B33/00Honing machines or devices; Accessories therefor
    • B24B33/02Honing machines or devices; Accessories therefor designed for working internal surfaces of revolution, e.g. of cylindrical or conical shapes
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B24GRINDING; POLISHING
    • B24BMACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B33/00Honing machines or devices; Accessories therefor
    • B24B33/08Honing tools
    • B24B33/084Honing tools having honing stones at the end of bars

Abstract

Method for fine machining a bore in a workpiece, in particular for fine machining a crankshaft bearing bore in a cylinder crankcase of an internal combustion engine, in which, starting from a prepared bore, a finished bore having a predefinable nominal dimension, a predefinable target structure of the bore inner surface and a predefinable target position of the bore axis is generated, characterized by at least one performance honing operation, wherein an honing of at least 0.5 mm is produced by honing the bore relative to the diameter of the bore, wherein the power honing operation is performed as an aligning honing operation such that the power honing operation translates the bore axis into Direction of the target position takes place, wherein a spindle distal end portion of the honing tool on one of the inlet side of the bore opposite outlet side in a counter-holder dre is stored, which is moved with an axial stroke movement of the honing tool with the honing tool.

Description

  • BACKGROUND AND PRIOR ART
  • The invention relates to a method for fine machining a bore in a workpiece, in particular for fine machining a crankshaft bearing bore in a cylinder crankcase of an internal combustion engine, according to the preamble of claim 1. Furthermore, the invention relates to a device suitable for carrying out the method.
  • The cylinder crankcase (ZKG), which is often referred to simply as "crankcase" or "engine block" to, is an integral part of internal combustion engines or internal combustion engines, such as those used in passenger cars or trucks, aircraft, ships or stationary equipment. The most common design are multi-cylinder engines whose pistons are connected via connecting rods with the rotating crankshaft, which forwards the power generated by the engine to wheels, propellers, propellers, generators or the like.
  • The crankshaft is located in series or V engines below, in a boxer engine between the cylinders and is supported on the cylinder crankcase in the bearings of the crankshaft bearing bore. The bearings are usually designed as a plain bearing, possibly also as a rolling bearing. In order to ensure a high concentricity of the crankshaft and thus to minimize undesirable signs of wear and vibrations during operation, the crankshaft must comply with high form tolerance requirements. The bearings are also closely tolerated in terms of their size and location in the cylinder crankcase.
  • The relatively narrow tolerances of the relevant parts of an internal combustion engine and a cylinder crankcase arise from the complex functions of these parts. The shape, the dimension and the surface topography of the cylinder bore are decisive factors for the wear, the friction, the oil consumption and the emission values of the internal combustion engine as well as the performance and the efficiency as a result of the friction. Above all, the compressed combustion chamber volume determines the compression of the engine. This has an impact on performance and combustion also influences emissions and engine noise.
  • The exact position of the crankshaft relative to the piston or to the cylinder bores is inter alia important for reducing wear on the highly loaded engine parts. These are in particular piston / piston pin, connecting rod and bearing of the connecting rod on the crankshaft and the bearing of the crankshaft in the cylinder crankcase. Not only the absolute position in the room, but also its angular position or orientation play a role in the position of the bore axis. For example, run in manual transmissions with clutch, the crankshaft and the input shaft of the transmission together. Therefore, a coaxiality of the two waves is crucial for a long service life.
  • When the crankshaft bearing and the coaxiality of the bearings is important to each other. The bearings should be as well as possible in alignment so that the crankshaft can run around and rests substantially uniformly at all bearing points.
  • The workpiece area around a crankshaft bearing bore is generally composed of two individual parts. These are in the most common case, the bearing webs of the cylinder crankcase on the one hand and the bearing cap screwed thereon on the other. Alternatively, the crankshaft bearing bore also lie at the interface of two cylinder crankcase halves, such as. B. in the boxer engine. The items are usually pre-machined in the unmounted state by semi-circular surface sections are made on the bearing webs of the cylinder crankcase and on the bearing caps. In a subsequent process step, the individual parts are screwed together so that in each case a substantially cylindrical bore section results from the semicircular surface sections in the region of a bearing point. Several in series with distance one behind the other hole sections then yield the entire crankshaft bearing bore.
  • The hole prepared in this way is then subjected to a fine machining. In order to achieve the tolerances in the production of cylinder crankcases, a combination of one or more drilling operations and subsequent honing operations is used today. The variety of operations is provided because irregularities resulting, for example, from the casting of the cylinder crankcase, necessitate relatively large discharges of several tenths of a millimeter or more at the same time but can also form and position tolerances in the lower micrometer range and thus require a high-precision machining.
  • Drilling has two main tasks. An object of the drilling operation is to establish the position of the entire crankshaft bearing bore with respect to a workpiece-fixed coordinate system, for example with respect to a corresponding datum surface on the cylinder crankcase. By means of the drilling operation, the setpoint position of the bore axis predetermined for the workpiece is thus generated. The other task of drilling is to position the individual bearings to each other, which is referred to in professional circles as "coaxiality" of the crankshaft bearing bore. With regard to the bore diameter, the cuts in the drilling operation typically lie in the range of several tenths of a millimeter, possibly even at one millimeter or above.
  • After drilling, a honing of the crankshaft bearing bore takes place. By honing, above all, the required final quality in terms of diameter tolerance, cylindrical shape and surface roughness is achieved so that the tolerances with respect to the predefinable nominal dimension and the predefinable target structure of the bore inner surface are maintained. The position and coaxiality of the crankshaft bearing bore should not be changed during honing, as they have already been determined by the upstream drilling operation. Therefore, for honing an articulated coupling between the honing tool and honing spindle is provided so that the honing tool can follow the already predetermined with respect to their position hole, without actively changing their position. The cutoffs relative to the bore diameter are typically in the range below 100 μm in the honing operation.
  • The EP 0 968 069 B2 describes a drill that is useful in mass production of cylinder crankcases for drilling crankshaft bearing bores.
  • From the DE 196 34 415 B4 For example, a honing tool is known which can be used, for example, in honing crankshaft bearing bores or other sectioned bores having aligned bore portions therein. The honing tool has at least one honing area which can be set according to the nominal dimension before the start of processing and which has a cutting area and a calibrating area, each with at least one cutting pad, and a guide cutting area with at least one cutting pad, the guide cutting area being radially expandable.
  • The DE 103 48 419 B3 describes a method for roughing the lateral surface of a bore, namely a cylinder surface in an engine block. In the method, a honing tool is inserted into the bore, the longitudinal axis of the bore having a offset from the finish machined bore prior to roughing. This offset is compensated during the scrubber operation so that an axis-correcting honing operation occurs. The honing tool is attached to a cantilevered work spindle.
  • The article "Modular Honing Machines Gain Importance" by T. Abeln, G. Flores and U. Klink in: Machine Market, 1/2, 2009, pages 24 to 27 refers in a section to the above-mentioned position honing and mentions that thereby the fine boring and the pre-honing of cylinder bores can be summarized. It is mentioned that the requirements for a removal of up to 0.8 mm in diameter require a radical redesign of the complete honing unit. Among other things, the honing tool is flanged directly to the honing spindle.
  • The utility model DE 79 02 603 U1 describes a device for holding workpieces, in particular gears, for honing work. An example shown workpiece holding device receives two workpieces, which are each received in rectangular workpiece receiving plates, which are arranged one above the other in the axial direction of the honing tool and are individually mounted for lateral movement transversely. The honing tool is rigidly clamped in a work spindle of the honing machine and mounted at its end opposite the clamping end in a bore of a guide bush, which in turn is mounted in a bore of a base plate of the workpiece holding device.
  • TASK AND SOLUTION
  • It is an object of the invention to provide a method for fine machining bores in workpieces as well as a device suitable for carrying out the method, with which, in particular, crankshaft bearing bores and other bores of relatively large length while maintaining maximum Precision machining requirements can be more finely machined from a relatively crude preparation than previously.
  • To achieve this object, the invention provides a method having the features of claim 1 and a device having the features of claim 8. Advantageous developments are specified in the dependent claims. The wording of all claims is incorporated herein by reference.
  • The invention results in a considerable shortening of the process chain with the potential for a much more economical implementation of fine machining. The honing process is used not only to set the diameter tolerance, cylinder shape and surface texture, but also to set the correct position of the bore axis relative to a workpiece-fixed reference frame. In the generation of the exact position of the bore axis, a correction or displacement of the position of the bore axis in the direction of its nominal position usually takes place. When drilling with axially spaced bore sections where it is required, at the same time an improvement of the coaxiality of the bore is achieved. As this usually relatively much material is removed in a relatively short time, this honing operation is referred to as "Leistungshonoperation".
  • The term "honing" in this application refers to a machining process with geometrically indeterminate cutting, in which multi-bladed honing tools perform a two-component working movement, which leads to a characteristic surface structure of the machined inner surface, which usually, but not necessarily, has crossed machining marks. The transferred from a honing spindle of a honing machine to the honing tool working movement is usually made of an axially reciprocating stroke movement and one of these superimposed rotational movement.
  • In comparison to drilling tools that work with geometrically determined cutting edges, honing tools have a considerably longer tool life, so that larger quantities can be machined without changing tools. While in drilling tools wear of the geometrically determined cutting can lead to a gradual change of engagement conditions and thus deterioration of surface quality and dimensional accuracy, the cutting performance of honing tools due to the self-sharpening effect of the cutting grains provided with cutting groups during the entire service life is substantially constant, so that even with large quantities machined workpieces largely consistent qualities of the surface microstructure can be achieved.
  • In the honing process one can distinguish between the classic honing and the so-called thorn honing. In classical honing honing tools are used with radially deliverable cutting groups during honing in order to gradually achieve the desired desired size of the bore by a plurality of strokes. In contrast, during mandrel honing, a mandrel honing tool preset to the specified size (finished size) is used, which usually has a conical cutting area and an adjoining, likewise intersecting, cylindrical calibrating area. The entire removal process requires Dornhonen usually only one or a few, z. B. maximum three, double strokes. Both honing methods can be used within the scope of the present invention alternatively or in combination.
  • Performance honing can completely replace the conventional combination of drilling operation and honing operation. As a result, the conventional separate Bohroperation and the necessary separate drilling station can be saved. In preferred embodiments, no drilling operation is interposed between the preparation of the prepared bore and the power honing operation. When machining crankshaft bearing bores, the performance honing operation may, for. B. immediately after assembly of the crankshaft bearing bore forming items (cylinder crankcase and bearing caps or the parts of the cylinder crankcase) done. The assembled or prepared in another way workpiece must be clamped only once in a workpiece holder, a time-consuming re-clamping is eliminated.
  • However, it is also possible to perform a drilling operation (eg fine boring or fine spindles) prior to power honing in order to pre-process the prepared hole for power honing.
  • One of the characteristics of the power honing process is the high material removal compared to conventional honing, which among other things enables the correct positioning of the bore axis or a displacement of the bore axis. The actual removal required on a workpiece depends on the preparation and can vary from workpiece to workpiece of a series. Often, at least one or several workpieces of a series produces a removal of at least 1 mm, wherein the removal may in particular also be between 1 mm and 2 mm. In the case of individual, particularly well-prepared workpieces or workpiece sections, the removal may also be less than 0.5 mm or less than 0.3 mm. The removal is usually well above 100 microns or 150 microns.
  • In order to enable economical finishing within short cycle times, in some variants of the method during the power honing process, material is removed at least in phases by means of geometrically indeterminate cutting edges with a material removal rate Q W = V / t which is significantly greater than with conventional honing. Here, V is the volume of the workpiece cut by machining and t is the machining time required for it, so that the dimension [mm 3 / s] results. For the volume V, the approximation V ≈ (π (D 2 - d 2 ) L) / 4 applies, where d is the (smaller) diameter of the bore before erosion, D the (larger) diameter after erosion and L the length of the bore Edit bore or the enlarged diameter bore section is.
  • In order to achieve comparability of numerical values, the time-wasting volume in this application is referred to a processing time t = 20 s (corresponding to a typical honing time) and a length L = 20 mm (corresponding to a typical web width of a single bearing web of a crankshaft bearing bore of a passenger car engine) , The normalized in this way removal rate is referred to herein as a "specific" removal rate and abbreviated Q W S.
  • If one now considers typical bores with nominal diameters in the range of 40 mm to 70 mm, then the specific chip removal volume is preferably more than 13 mm 3 / s (for 40 mm) or more than 22 mm 3 / s (for 70 mm). , These typical lower limits are usually clearly exceeded. For a nominal diameter of 40 mm, z. Q W S > 30 mm 3 / s, occasionally Q W S > 50 mm 3 / s or even Q W S > 100 mm 3 / s. For a nominal diameter of 70 mm, z. Q W S > 50 mm 3 / s, occasionally Q W S > 100 mm 3 / s or even Q W S > 150 mm 3 / s.
  • High chip removal rates may occur. a. be promoted by unconventionally high cutting speeds, which in turn depend on the rotational speed (speed) and / or the lifting speed of the honing tool.
  • In some process variants, the honing tool is rotated during the power honing at least in phases at a speed of more than 400 U / min, wherein the speed is preferably at least in phases more than 1000 U / min, in particular more than 1500 U / min. Often the speed is in the range of 1500 rpm to 2500 rpm.
  • Alternatively or additionally, the honing tool during classical honing (with expandable honing tool) during the power honing at least in phases with a maximum lifting speed of more than 20 m / min are moved, the maximum lifting speed preferably at least in phases between 30 m / min and 50 m / min or even more than 50 m / min. When mandrel honing (with preset tool) maximum lifting speeds of more than 12 mm / min, in particular more than 20 m / min can be achieved.
  • The spindle drive of the honing machine is then designed accordingly in terms of maximum speed, maximum lifting speed and drive power.
  • A special design of the cutting means may favor the achievement of high Abtragsraten or Zeitspanvolumina and other processing criteria. For example, it may be convenient to use relatively long cutting strips. In some embodiments, a honing tool is used which has a plurality of cutting bars distributed around a tool body, wherein a length of the cutting bars is more than 60%, in particular more than 80% of the axial bore length. Alternatively or additionally, the length of the cutting bars can be more than three times or more than four times or more than five times the effective diameter of the honing tool. For the processing of typical crankshaft bearing bores, z. B. with diameters in the range of 40 mm to 70 mm, the cutting bar length z. B. at 200 mm or above, z. B. between 300 mm and 400 mm. When using relatively long cutting strips can be processed simultaneously in honing tools with radially deliverable cutting edges large areas of the bore. When using conical cutting bars (Dornhonen) can be brought in a single stroke a large change in diameter. Relatively long cutting bars are also favorable with regard to the straightness of the bore produced in the rule.
  • In the power honing relatively coarse-grained cutting means are preferably used, especially those with very hard cutting grains, eg. B. with diamond cutting grains. If the power honing process is carried out in one stage, average particle sizes in the range between approximately 50 μm and approximately 150 μm (with diamond strips, for example, from D54 to D151) will often be advantageous in order to achieve a good compromise between high removal rate and at the same time sufficiently fine To obtain surface structure of the machined inner surfaces after completion of the power honing. In particular, in a multi-stage, z. B. two-stage, Leistungshonbearbeitung even coarser cutting means can be used. For example, in a first stage, cutting means having mean grain sizes of more than 150 .mu.m can be used, for diamond cutting grains z. Up to D181. The second stage can then be driven with much finer grain size, z. B. with D35 to D64 in the classical variant (expandable honing tool) or with D91 to D126 Dornhonen.
  • In some variants of the method, the workpiece is fixed in a workpiece position and the honing tool is inserted coaxially to the desired position of the bore axis in the bore and moved within the bore. Incorrect positioning of the actual bore axis (actual bore axis) with respect to the workpiece-fixed reference system after pre-machining thus causes the honing tool to be eccentrically inserted into the prepared bore and the tool axis remains in position during the entire power honing operation while the actual position of the bore axis is in the As the machining progresses, it approaches its intended position dictated by the position of the tool axis.
  • In order that the position of the bore axis can be predetermined by the power honing and optionally changed by axially and / or circumferentially unequally distributed material removal, an exact determination of the position of the tool axis (with respect to position in space and angular position or orientation) is provided during honing. This can be achieved by a radial guidance of the honing tool. Preferably, the honing tool with a spindle-side coupling structure is rigidly coupled to a honing spindle or to a rigidly coupled to the honing spindle drive rod and guided at least one axially spaced from the coupling structure bearing point, wherein between the coupling structure and the bearing at least one cutting group of the honing tool is arranged , The radial forces acting on this cutting group can thus be absorbed on both sides of the cutting group, whereby the position of the tool axis in the region of the cutting group remains stable even with strong lateral forces. Especially with axially long holes, z. B. with a length-diameter ratio of significantly more than 3 or more than 4 or more than 5 or more than 6, this type of rigid guidance of the axial movement has been proven.
  • According to the claimed invention, a spindle distal end portion of the honing tool is rotatably mounted on the exit side of the bore opposite discharge side in a counter-holder. This variant is possible with all workpieces with a continuous bore. The counter-holder is moved with the honing tool during an axial stroke movement of the honing tool, either passively (without its own displacement drive) or actively (by means of displacement drive). In a co-moving counter-holder, the clamping length of the honing tool between the spindle-side coupling structure and the anvil remains constant during the lifting movement, which can have a positive effect on the quality of machining.
  • When not belonging to the claimed invention variants, it is also possible that the counter-holder is fixed to a machine-fixed position, so that the honing tool moves during the lifting movements relative to the counter-holder. Such embodiments are structurally particularly simple, as can be dispensed with linear guides and possibly a drive for the anvil.
  • Variants with guide points in front of and behind the bore (front and rear guide) and / or variants with inner guide are also possible.
  • The crankshaft bearing bore is an example of an axially relatively long bore having a plurality of bore portions arranged in alignment with each other and aligned in series with each other. In such workpieces, it is possible that at least one tool storage for the honing tool lies between two adjacent bore sections. In some embodiments, such an "inner guidance", i. H. a tool guide device in the interior of the workpiece between two adjacent bore portions, and thus between the bore entry and hole exit, provided. The axial distance between the bearing points for the honing tool can be kept short in this way, whereby a particularly stable against lateral forces storage or leadership achieved and a bending of the honing tool between bearings can be prevented or reduced.
  • In a variant suitable for an inner guide, a tool bearing serving as a guide device has a bearing element fixed to the machine on or in which a guide element freely rotatable relative to this bearing element is rotatably mounted, which during operation rotates with and guides the rotating honing tool and guides it supported against radial forces. The rotatable guide element may have at least one driver element which is provided for engagement with a recess provided on the tool body of the honing tool so that the guide element can be made simple and robust as a passive element (without its own drive). Axially continuous recesses may be provided on the inner circumference of the guide element, through which the cutting elements (eg, honing stones) attached to the honing tool pass without contact.
  • The inner guide can also be useful in conjunction with a group tool in which a plurality of axially spaced apart cutting groups for simultaneous honing of a plurality of axially spaced bore sections are arranged on a tool body, wherein the number of cutting groups preferably the number of simultaneously processed Bore sections corresponds. A group tool for a four-cylinder in-line engine block can, for. B. have five cutting groups for the five bearings. An inner tool storage can then attack between two cutting groups on the tool body. There may be provided two or more inner tool bearings, for. B. one for each gap between cutting groups.
  • The invention also relates to a device suitable for carrying out the method for fine machining a bore in a workpiece, in particular for fine machining a crankshaft bearing bore in a cylinder crankcase of an internal combustion engine, with at least one drivable by a spindle drive honing spindle to which a honing tool is coupled or coupled, and a Bearing device for axial guidance of a lifting movement of the honing tool.
  • Preferably, the honing tool is rigidly coupled or coupled to the honing spindle, directly or with the interposition of a rigid drive rod, and the bearing device is adapted to engage the honing tool at a bearing point arranged at an axial distance from a spindle-side coupling structure of the honing tool in such a way that the coupling structure and the Bearing at least one cutting group or a portion of a cutting group of the honing tool is arranged. A front and / or a rear guide and / or an inner guide may be provided.
  • The foregoing and other features will become apparent from the claims and from the description and drawings. In this case, the individual features can be implemented individually or in the form of subcombinations in one embodiment of the invention and in other areas, and can represent advantageous embodiments. Preferred embodiments will be explained with reference to the accompanying drawings.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • 1 shows a schematic side view of a horizontal honing machine for power honing of crankshaft bearing bores;
  • 2 shows various views of an engine block with crankshaft bearing bore;
  • 3 shows a schematic side view of an arrangement with an end-opposed group tool, which has its own group of cutting strips for each bore section;
  • 4 shows a schematic side view of an arrangement with a group tool, which is mounted in the interior of the workpiece between adjacent bearing webs in the region between cutting groups;
  • 5 shows a schematic side view of the processing of a crankshaft bearing bore with an end-mounted Dornhonwerkzeug with conical cutting area;
  • 6 shows a schematic side view of an arrangement with an end-mounted honing tool with conical cutting area and integrated, two-stage front group;
  • 7 shows a schematic side view of an arrangement with a mounted in a front and a rear guide honing tool, which is fastened by means of a drive rod to the honing spindle; and
  • 8th shows a schematic side view of an arrangement with a directly rigidly coupled to the honing spindle, equipped with continuous cutting edges honing tool, which is rotatably mounted in the interior of the workpiece between adjacent bearing webs by means of an inner guide;
  • DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
  • In 1 is a schematic side view of a designed as a horizontal honing machine device for fine machining of crankshaft bearing bore in cylinder crankcases shown. The honing machine is set up for a complete fine machining of the crankshaft bearing bore immediately following the assembly of the crankshaft bearing bore forming parts of the engine block. The honing machine is designed so that on the one hand the correct position of the bore axis of the crankshaft bearing bore with respect to a workpiece-fixed reference system can be adjusted with the aid of the manufacturing process honing and on the other hand the tolerances with respect to diameter, cylindrical shape and surface structure of the bearing points can be produced.
  • On a machine bed 102 the honing machine 100 is a horizontally movable spindle slide 104 mounted, which has a headstock 106 carries in which the honing spindle 110 the honing machine with horizontal spindle axis 111 is rotatably mounted. The electric rotary drive 107 for the spindle rotation is mounted on the spindle box. The one for the stroke movement parallel to the spindle axis 111 required lifting drive 105 is mounted in the machine bed and drives a horizontally oriented threaded spindle, on the one with the spindle slide 104 coupled mother is running.
  • The lifting drive is designed for maximum lifting speeds in the range of 40 m / min or 50 m / min or more, the rotary drive for maximum speeds from about 2,500 rpm to 3,000 rpm. The available drive power for stroke and rotation is more than 10 kW.
  • The workpiece to be machined 150 is in the example a cylinder crankcase for a straight four-cylinder engine (see. 2 ). The workpiece is fixed on a workpiece holder 140 mounted, which is attached to the top of the machine bed. By means of a mechanically or manually operable actuator, the workpiece holder is in a horizontal, perpendicular to the spindle axis 111 (Z-axis) extending direction (X-direction) can be moved horizontally. The workpiece lies with its flat oil sump connection surface 156 on the workpiece holder and is using indexing pins 142 accurately positioned so that over the position of the workpiece holder 140 the exact position of the workpiece relative to the spindle axis 111 can be determined.
  • The oil pan interface 156 used in this setup as a production reference surface for fixing the workpiece-fixed coordinate system relative to the machine-fixed coordinate system. In other variants of the method is already processed previously opposite top surface 154 (Mating surface for the cylinder head) as a manufacturing reference surface.
  • On the spindle-distal side of the workpiece holder is on the machine bed one parallel to the spindle axis 111 extending, horizontal linear guide device 130 fixed on a sled 132 running, which is a bearing element 134 for a rotatable chuck 135 carries, which in the bearing element about a coaxial with the spindle axis 111 extending horizontal axis is rotatably mounted. The horizontally movable, rotatable chuck 135 is provided as a counterhold for the distal end of the honing tool. The sled 132 is in the example with the carriage 104 the lifting drive mechanically positively coupled. It is also possible that the movement of the passive sled 132 is generated exclusively by the moving tool. In another variant, the anvil has its own drive, which is synchronized with the lifting drive of the honing spindle.
  • The honing tool 170 is by means of a rigid drive rod 120 rigid with the honing spindle 110 connected. For this purpose, the releasable coupling structure 125 formed between the drive rod and the honing spindle as a non-rotatable, rigid rigid coupling structure, for example in the form of a screw or a simple flange connection. Also the detachable connection between drive rod 120 and honing tool 170 is rigid and rotatable. For this purpose, the spindle-side coupling structure 172 of Honing tool, for example, be designed as a screw thread, which cooperates with a corresponding counter-thread on the tool-side end of the drive clamp.
  • In other embodiments, the spindle-side coupling structure of the honing tool is attached directly to the tool-side end of the honing spindle, so that working without interposed drive rod (see. 5 ).
  • The honing tool 170 has an elongated-cylindrical tool body 174 , on the spindle side, the spindle-side coupling structure 172 and on the spindle side facing away from a cylindrical guide shaft 176 are formed. The tool axis running centrally in the tool body 175 is coaxial with the spindle axis due to the rigid coupling 111 , In radial openings of the tool body sit radially movably mounted support strips, which axially elongated cutting strips 178 Wear with diamond cutting material. A radial delivery of the cutting strips of this expandable honing tool is carried out by means of a not shown, electric or hydraulically driven, positive feed system, which comprises a running through the honing spindle and the drive rod in the honing tool, axially displaceable feed rod, at the end of an expansion cone with simple or multiple support is arranged, which cooperates with conical mating surfaces on the inner sides of the support strips to ensure axial displacement of the Zustellstange a radial delivery of the cutting bars without tilting the cutting bars.
  • The measured parallel to the tool axis length of the cutting bars is preferably more than 60%, possibly even more than 70% and in the example even slightly more than 80% of the length of the honing tool to be processed crankshaft bearing bore, which on the one hand promotes high Abtragsleistungen and on the other hand favorable the straightness of the bore or the coaxiality of the processed bearing webs effect.
  • The far-off end of the leadership shaft 176 is in the illustrated processing configuration of the honing machine in the rotatable chuck 135 clamped. This is the result of the cutting strips 176 formed single cutting group of the honing tool between two the position of the tool axis stabilizing bearings arranged. One of the bearing points is the bearing of the honing spindle 110 in the headstock 106 formed, the opposite bearing by that on the slide 132 mounted and with the honing tool axially movable chuck 135 which serves as an abutment.
  • Some peculiarities of the workpiece 150 are determined by 2 explained at the 2A a longitudinal section, 2 B a plan view parallel to the bore axis of the crankshaft bearing bore and 2C a plan view shows parallel to the bore axes of the cylinder bores. For engine blocks and the functional surfaces and holes formed there are sometimes very tight tolerances to ensure reliable operation. The cylinder bores 151 are tolerated with respect to cylinder shape and diameter of the cylinder bore typically in the range of a few micrometers, with particular attention being paid to the surface topography. For the distance ZA of the bore axes 152 The cylinder bores, the so-called gauge, are typically tolerances in the range of 100 microns.
  • A slightly larger form tolerance than in the cylinder bores have the bearings for the crankshaft in the crankshaft bearing bore 160 , The crankshaft bearing bore is compared to the cylinder bore (typical ratio of length to diameter 2.5 maximum) a relatively long bore, typically with a length-diameter ratio LDV, which is substantially greater than 2.5 or 3 and in the example is about 6. The crankshaft bearing bore has five bore sections in a four-cylinder clean engine 161 to 165 which are arranged in alignment with each other in the mutual axial distance from each other in series. The bore sections form the bearings for the crankshaft. When the crankshaft bearing particular coaxiality of these bearings is important to each other. The bearings should be aligned as well as possible so that the crankshaft can run around and rest evenly on all bearing points. The coaxiality of the individual bearings should not exceed 15 microns or not significantly. For the definition of "coaxiality" reference is made to DIN ISO 1101, the content of which is included in this description.
  • Another important criterion regarding the crankshaft bearing bore is the position of its bore axis 166 which defines the position of the crankshaft axis during operation of the engine. The term "position of the bore axis" is intended here to include both the absolute position of this axis in space, as well as their angular position, ie their orientation in space. The vertical position can z. B. by the distance ADA of the bore axis to the top surface 154 of the engine block at the hole entry or at the hole exit (or corresponding distance AÖ to the oil sump connection surface 156 ) To be defined. The distance between crankshaft and top surface is one of the criteria for the compression of the engine. Although tolerances in the micrometer range are generally not required here, tolerances in the range of less than 100th of a millimeter are desirable. The exact position of the crankshaft or the bore axis of the crankshaft bearing bore to the cylinder bores is also important for reducing wear on the highly stressed components, which include not only the piston / piston pin, connecting rod and connecting rod bearings on the crankshaft and the bearings of the crankshaft in the cylinder crankcase. Also the angular position of the bore axis 166 , ie their orientation with respect to a workpiece-fixed reference system, plays a role here. Typically, the position of the bore axis should be 166 vary with respect to the total bore length BL maximally 0.05 mm, whereby this value both for the vertical direction (direction deck surface) and transversely thereto (horizontal direction in 2 B ) applies.
  • With the help of the honing machine 100 It is possible, in an engine block immediately after assembly of the crankshaft bearing bore forming parts, the crankshaft bearing bore 160 To finish by honing so that all tolerances can be achieved with respect to the position of the bore axis and also with regard to the required surface quality of the bearing points. This can be done as follows.
  • First, the workpiece 150 , So the cylinder crankcase, immediately after assembly, ie without intermediate drilling, on the correctly positioned, very torsionally rigid executed workpiece holder 140 with the help of the indexing pens 142 Spaced exactly so that the spindle axis 111 the honing spindle is coaxial with the desired desired position of the bore axis of the crankshaft bearing bore. As a rule, this axis position will not be centered, but eccentric, at least with respect to some of the bore sections to be machined. The bore sections also have in relation to their nominal diameter undersize, which is removed by honing. Depending on the quality of the preparation, the undersize may be in the range of at least 0.5 mm or more, for example in the range between 1 mm and 2 mm.
  • After tightening the workpiece, the honing tool is introduced into the crankshaft bearing bore from the spindle-facing inlet side so far that the spindle-distal end portion of the guide shaft 176 in the chuck 135 introduced and can be clamped there. The cutting strips are in this preparation phase in its retracted position, so that the rigidly coupled to honing spindle and drive rod honing tool can be partially inserted from this without touching the bearing inner sides in the crankshaft bearing bore.
  • Thereafter, the lifting drive, the rotary drive and the drive of the delivery system for the widening of the cutting group are turned on. In order to achieve a possibly substantial material removal in relatively short cycle times, the maximum lifting speeds and the maximum speeds are typically significantly higher than the corresponding values for the conventional honing machining, as are customary, for example, in the machining of cylinder bores. Maximum lifting speeds may be more than 20 m / min or more than 30 m / min to, for example, about 40 m / min, the maximum speeds typically being more than 1,000 rpm or more, at least during a honing process, rarely more than 2,500 rpm will be required.
  • With progressive expansion (increase in diameter) of the honing tool are then machined by the high-speed and rapidly oscillating axially honing tool, the innermost sections of the bearings through the multi-bladed cutting edges. With increasing expansion of this one-sided partial section is gradually over in a running over the entire circumference of a bore section full section. In this case, all bore sections gradually get one to the tool axis 175 centered, cylindrical shape, so that on the one hand results in a displacement of the actual bore axis in the direction of the predetermined by the position of the tool axis target position of the bore axis and on the other hand, an improved coaxiality of the bearings. The cutting speeds may be in the range of 250 m / min or more, for example more than 300 m / min or more than 350 m / min or more than 400 m / min. The achievable chip removal rate of the fine machining can be significantly higher than in conventional honing operations, for example in the range of more than 200 mm 3 / s or even more than 500 mm 3 / s or more, at least in the final phase when material is removed at all bore sections ,
  • In order to determine the chip removal volume, in this application a specific removal rate Q W S = V / t [mm 3 / s] is assumed, where V is the volume of the workpiece cut off by machining and t is the required processing time. For the volume V, the approximation V ≈ (π (D 2 - d 2 ) L) / 4 applies, where d is the (smaller) diameter of the bore before erosion, D the (larger) diameter after erosion and L the length of the bore Edit bore or the enlarged diameter bore section is. The specific chip removal volume here is based on a processing time t = 20 s (corresponding to a typical honing time) and a length L = 20 mm (corresponding to a typical web width of a single bearing web of a crankshaft bearing bore of a passenger car engine). The values given in Table A (see end of the description) for the chip removal rate are given for typical nominal bore diameters of 40 mm to 70 mm. In those columns where the number of lands is 1, the values correspond to the specific chip removal volume for the four different diameters.
  • For a typical crankshaft bearing bore of a series four-cylinder with 60 mm diameter and 5 bearing webs (bore sections), each with 20 mm length results in z. B. a minimum value of the Zeitspanvolumens of about 94 mm 3 / s (corresponding to a removal of 0.2 mm in diameter), and a value of 942 mm 3 / s corresponds to a removal of 2 mm.
  • Frequently achieved (total) Zeitspanvolumina in the crankshaft bearing bore machining with typical bore diameters of about 40 mm to about 70 mm are in the range of about 300 mm 3 / s to about 700 mm 3 / s. This is a significant increase over conventional honing methods, where today, when honing crankshaft bearing bores, maximum total chip removal rates in the range of up to about 45 mm 3 / s are typically achieved.
  • The high drive power in conjunction with unconventionally high speeds and lifting speeds allow a significant increase in cutting speed compared to conventional honing. As a result, abrasions in the range between 1 mm and 2 mm in diameter can be achieved within normal honing times of, for example, 20 s to 25 s, which corresponds to a removal rate of significantly more than 200 mm 3 / s or even more than 500 mm 3 / s. The process parameters of the power honing operation can thus be adjusted so that the honing times for the power honing operation are in the range of the honing times of the conventional honing machining of a crankshaft bearing bore, ie in a maximum of 20 to 25 seconds. However, since the power honing operation can save the previously required upstream drilling operation, a faster and thus more economical fine machining of crankshaft bearing bores is possible with at least constant quality.
  • By honing machining in the cases of not perfectly prepared workpieces an active change in position of the bore axis of the crankshaft bearing bore is brought about. Depending on the state of preparation, displacements of the bore position can be achieved up to 150 μm (based on the total bore length), if necessary also over it. At the same time an accuracy of the Bohrungsachsenposition of less than ± 20 microns can be achieved due to stable against lateral forces bilateral bearing of the honing tool in the rule.
  • In this case, coaxialities of less than 30 microns or even less than 15 microns can be achieved.
  • In order to be able to relocate the bore position significantly, a stiff and precise machine concept has been implemented in the honing machine. Thus, the honing spindle on the carriage guide of the spindle to the workpiece holder precise and rigid units are provided which have little in common with corresponding units of traditional honing machines. For example, the honing spindle is typically mounted in conventional honing machines with simple, non-strained angular contact ball bearings. In contrast, the storage inside the headstock 106 a higher quality storage before, which can be biased, so a preload radial / thrust bearing.
  • Furthermore, working with comparatively long and slender honing tools, which are exposed when moving the bore axis optionally high, one-sided Abdrängkräften. The position of the tool axis remains stable under these difficult conditions coaxial with the target position of the bore axis, since the honing tool on the spindle side rigidly connected to the honing spindle and on the spindle side facing away from the anvil 135 is counter-stored.
  • In the embodiment of 1 a traveling counter bearing is provided, which is moved by the stroke of the spindle carriage and therefore does not require its own drive (passively moving counter bearing). The stroke of the counter bearing can be, for example, in the range of 500 mm. Alternatively, a fixed counter-bearing may be provided, for example in the form of a fixedly mounted on the machine bed bearing blocks, in which a coaxial with the spindle axis 111 arranged, cylindrical bearing opening is provided, through which the cylindrical guide shaft 107 and 176 backlash-free and can be passed through low friction by hydrodynamic lubrication.
  • A combination of an input-side front guide and an output-side rear guide is possible (see. 7 ).
  • The honing machine 100 is designed as a horizontal machine, so that integration into automated production lines is particularly easy. The horizontal structure is also favorable for the accessibility of the machine components and in view of the fact that due to the counter bearing a relatively long in the axial direction construction is needed. However, a construction as a vertical machine, ie with vertically aligned spindle axis, is basically possible.
  • In many cases, the power honing process can be performed in a single processing step with a simple expanding honing tool. Due to the required high removal rates cutting bars with diamond cutting grains are advantageous, but if necessary, other hard cutting grain materials, such as boron nitride, can be used. When working with average grain sizes in the range between about 50 microns and about 100 microns to 150 microns, so a good compromise between relatively high removal rate and a sufficiently low roughness of the finished inner surfaces can be achieved for the often only residual roughness of less as about 15 microns R z (average roughness) are required.
  • In particular, when lower residual roughness is desired, it is also possible to work in two successive stages. In a first stage, with relatively coarse grains, a substantial portion of the material removal can be achieved and in a second stage a comparatively lower residual removal and the required surface roughness can be produced. For this purpose, a double widening honing tool can be used, in which a first set of cutting bars for the first stage coarse grain size, for example, up to about 200 microns average grain size, while the cutting strips a second, independently deliverable cutter set finer grain size, for example, less than 80 microns or less than 50 microns average grain size. In the case of a double widening honing tool, one and the same honing tool can be used for two consecutive or temporally overlapping processing stages. In other variants of the method, a tool change between the processing stages or another processing station is provided. It is also possible to use the first processing stage of the honing with an expandable honing tool of the 1 to perform a subsequent second, finer processing stage with a finished set honing tool with conical cutting area, as for example in connection with 5 is explained.
  • Based on 3 and 4 Embodiments are explained in which instead of an expandable honing tool with a single set of relatively long cutting strips (see 1 ) so-called group tools are used. The honing tool 370 in 3 is a group tool where the cylindrical tool body 374 five with mutually axially spaced cutting groups 376A to 376E are arranged. The number of cutting groups corresponds to the number of bearings to be machined. The axial lengths of the individual cutting strips of the cutting groups are relatively short and are approximately of the order of the axial length of a bearing section to be machined (for example from 20 mm to 30 mm). As a result, longer sections of the tool body are free between the individual cutting groups. All radially expandable or contractible cutting groups are actuated by the same feed system, which has a Zustellstange inside the honing tool with five assigned to each cutting groups Zustellkoni. All cutting groups can therefore be delivered simultaneously to the same effective Bearbeitungsmaß. With the group tool a simultaneous processing of all bore sections is possible, but in contrast to the embodiment of 1 the stroke length is much shorter. It may, for example, on the order of magnitude correspond to the length of the cutting strips in order to guarantee a cylindrical shape of the inner surface over the respective axial Eden of the bore sections in the case of bilateral overflow. As with the embodiment in 1 is the axial guidance of the honing tool spindle side by rigid coupling to one with the honing spindle 310 rigidly coupled drive rod 320 and at the distal end of the spindle by a moving counter-holder 335 ensured.
  • In the embodiment of 4 becomes a group tool 470 used, also by means of a rigid drive rod 420 rigid with the honing spindle 410 is coupled. The counter bearing of the honing tool 470 However, it is not realized by an acting on the distal end spindle counter-holder, but by "inner" tool guiding devices 436 . 437 in the interior of the workpiece, ie in the area between inlet side and outlet side, between the cutting groups of the group honing tool on the tool body 474 attack and support this against transverse loads and lead axially. The Tool guidance device 436 . 437 are fixed on the machine bed or workpiece holder by screws or otherwise, so do not move with the lifting movement of the honing tool. Such between two adjacent bore sections 462 . 463 respectively. 463 . 464 engaging tool guide means may be provided in addition to an end abutment to provide support for the honing tool against deflection in the central region of the long workpiece bore. As in 4 However, such internal tool guiding devices (one or more) but also instead of an end-engaging counter-holder can be used. In any case, optionally, a tool guiding device may be provided in each intermediate space between adjacent bore sections. Since in this embodiment, the axial distance between adjacent bearing points for the honing tool can be kept low, against axial forces particularly stable axial guidance and storage of the honing tool is possible.
  • In the embodiment in 5 For honing a crankshaft bearing bore, a honing tool preset to the specified dimension (finished dimension) is used 570 used, without the interposition of a rigid drive rod directly to the honing spindle 510 is rigidly attached. A spindle-facing, cylindrical guide pin 576 is similar to the embodiment of 1 in a rotatable chuck of a passive with the honing tool mitbewegbaren counter-holder 535 clamped in order to counteract possibly unilaterally acting Abdrängkräfte during honing the position of the tool axis 575 always to maintain the desired target position of the bore axis. The honing tool 570 has a relatively long conical cutting area 577 and a spindle side immediately adjacent thereto, substantially cylindrical cutting area 578 whose outer diameter corresponds to the desired finished dimension of the bore sections. The diameter of the conical cutting area increases continuously from the spindle-facing front end to the spindle-facing end with a cone angle of a few degrees.
  • Although the cutting edges in the conical cutting area and in the calibration area are manually adjustable before installation in the honing machine, a delivery during honing operation, but not provided and not necessary, so that the design effort for a delivery system can be omitted. Since the honing tool is exactly guided with respect to its axial movement by the rigid coupling to the honing spindle and the counter-holder on the side facing away from the spindle, the honing tool requires no optionally expandable guide rails for support within the bore, so that the honing tool can have a relatively simple construction ,
  • While in conventional honing with expandable honing tools many double strokes are required in connection with a gradual widening of the honing tool, the entire removal process using such Dornhonwerkzeuge usually requires only a double stroke or a few double strokes. The axial stroke speed is typically lower by a factor of 5 to 10 than in the case of corresponding honing methods with expandable honing tools. The axial stroke speeds may be in the range of 12 m / min or more in the power honing example. Due to the high spindle speeds, which can be up to 2500 rpm or even up to 3000 rpm in this machining variant, in conjunction with the relatively low lifting speed, the bore sections are gradually brought to finished dimensions when the honing tool is pushed through and at the same time, if necessary, with regard to their position corrected so that after completion of one or two double strokes the actual position of all bore sections with the through the tool axis 575 predetermined target position coincides and the inner surfaces of the bore sections have the desired cylindrical shape and surface structure.
  • In the performance honing in 6 becomes a thorn honing tool 670 used, which is similar to the embodiment of 5 a conical cutting area 675 and a spindle side adjoining cylindrical Kalibrierbereich 678 Has. The spindle-facing end is via a rigid drive rod 620 with the honing spindle 610 rigidly coupled, at the end facing away from the spindle is a cylindrical guide pin 676 whose end is in the chuck of a mitbewegbaren counter-holder 635 is clamped.
  • A special feature of the honing tool is that in the feed direction in front of the conical cutting area 677 a multi-level opening act 690 is arranged, which is optimized for particularly high removal rate. The opening act 690 has one to the leadership 676 subsequent first ring 691 first cutting elements 692 wherein the effective outer diameter of the first ring is slightly larger than the outer diameter of the guide shaft but smaller than the minimum diameter in the conical cutting region. This is followed by a second ring 693 second cutting elements 694 whose effective outer diameter is greater than that of the first ring 691 and is substantially equal to the effective diameter at the tapered end of the tapered cutting area. The cutting elements of the multi-stage Supporting group each contain a variety of bound in a relatively hard bond, hard cutting grains, such as diamond, the grain size can be significantly larger than in the conical cutting area. The cutting elements of the preliminary group operating in the manner of end cutters can produce a strong, stepwise removal in diameter during the first advance of the honing tool, so that the diameter enlargement to be produced by the conical cutting region is only slight. As a result, the quality of the finished bore can be further improved with the same honing time. One-stage pre-groups or those with three or more rings of different diameters are also possible.
  • In a non-illustrated embodiment, the cutting elements of the preliminary group respectively defined cutting, so that initially cut with defined cutting in the advancing movement of the honing tool and immediately honed with indeterminate cutting. In this way, a drilling operation and immediately afterwards a honing operation on the crankshaft bearing bore can be performed in a single working movement of the honing tool. Such a honing tool with pre-group can also be used independently of the other features of the invention with advantage.
  • Instead of mitbewegbaren counter-holder 635 It is also possible to provide a stationarily mounted, stable counterbearing in the manner of a honing bush, in which the spindle facing away from the guide of the honing tool is guided free of play and axially slidable. Instead of the rotatable chuck can be provided on the counter-holder of this or another embodiment, a conical tip, which engages in a concave-tapered receiving opening of a spindle facing away from the honing tool to receive the honing tool clearance.
  • The 7 and 8th show further possibilities, a reliable compared to its diameter relatively long honing tool with a long cutting strip area in a long bore, namely a crankshaft bore, and to guide stable against transverse forces. In the embodiment of 7 is the elongated honing tool 770 over a limited flexible drive rod 720 with the honing spindle 710 connected. On the spindle-near and the spindle-distant side of the cutting edges 778 the substantially cylindrical tool body forms cylindrical guide shafts, namely a spindle facing away from the guide shaft 776 and a spindle-like leadership shaft 777 , at the free end of the coupling structure is mounted for coupling to the drive rod. The spindle-distal guide shaft is located in a spindle-distal, arranged on the output side of the workpiece rear guide bushing 731 guided axially movable. The spindle-facing leadership 777 is on the input side of the workpiece in a correspondingly shaped front guide bushing 732 axially slidably guided. The center axes of the guide bushes determine the position and orientation of the tool axis and thus also the position and orientation of the finished crankshaft bearing bore. An end restraint is not required here.
  • In the embodiment of 8th is that with continuous, long cutting strips 878 equipped honing tool 870 in the interior of the workpiece between two axially adjacent bearing webs with the aid of a tool storage 890 radially immovable and rotatably guided about the tool axis. In the 8A in an axial section and in 8B shown in plan view "inner" tool storage 890 has a plate-shaped bearing element 891 , which is attached to the top of the machine bed. In a cylindrical opening of the bearing element sits a substantially annular guide element 892 , with the help of a rolling bearing against the machine-fixed bearing element 891 Is stored unlimited rotation. The guide element 892 has an outer diameter of the honing tool adapted, axially continuous guide opening 893 for passing the honing tool. Over the circumference of the guide element are on its inside a plurality of uniformly distributed over the circumference radial recesses 894 provided, the number of which corresponds to the number of cutting strips and which are dimensioned so that the cutting bars fit into the recesses even at maximum expansion of the honing tool, without touching the guide element. On the annular guide element 892 is a driver element 895 fastened, which via the inner circumference of the annular part of the guide element inwardly into the otherwise largely circular passage opening 893 protrudes. The inwardly projecting portion is dimensioned so that it is substantially free of play in the circumferential direction in a tool body 874 the honing tool provided longitudinal groove 879 fits, which extends over the entire length of the tool body centrally between two circumferentially adjacent cutting strips parallel to the tool axis.
  • Before the honing process starts, it becomes directly rigid with the honing spindle 810 attached honing tool 870 pushed from the input side into the crankshaft bearing bore and passes first with its spindle distant guide shaft 876 the guide opening 893 the inner tool storage 890 , The relative rotational position of honing tool and rotatable guide element 892 is chosen so that the inwardly projecting portion of the driver element 895 already in the area of the spindle away Guide shank in the longitudinal groove 879 is threaded largely free of play. As a result, it is ensured for the further introduction of the honing tool that the cutting edges 878 without touching the guide ring 892 can be passed through this. Once the honing tool has been inserted far enough, the free end of the guide shaft becomes 876 in the counterholder 835 clamped. During honing, the honing tool moves in accordance with the axial stroke in the guide hole 893 back and forth while simultaneously by the rotation of the honing tool on the driver element 895 the annular guide element is rotated within the bearing element. As a result, a reliable support of the honing tool is ensured within the workpiece, so that a deflection of the long honing tool is largely avoided even with strong radial forces. Because the rotatable guide element 892 is passive, ie has no own drive, but is taken over the movement of the honing tool, such a solution is relatively inexpensive and at the same time very robust and reliable.
  • Such, in a space between axially adjacent bore sections positionable "inner guide" can also in other embodiments, for example in the in 1 be realized embodiment shown. It can also be provided two or more inner guides. On an end-side abutment can optionally be waived, especially if in the last end-side bearing web gap an inner guide is attached.
  • The crankshaft bearing bore is a typical example of a relatively long bore, i. H. a bore with a relative to the bore diameter relatively large axial length. "Long holes" for the purposes of this application typically have a length-to-diameter ratio LDV of significantly more than 2.5 or 3, wherein LDV z. B. may be more than 4 or more than 6 or more than 8. In contrast, have "short holes, such as cylinder bores in internal combustion engines, typical length-to-diameter ratios of maximum 2.5 LDV. The devices and methods described in this application are particularly optimized for the machining of long holes, but can in principle be used even with short holes.
  • Figure DE102010010901B4_0002

Claims (11)

  1. Method for fine machining a bore in a workpiece, in particular for fine machining a crankshaft bearing bore in a cylinder crankcase of an internal combustion engine, in which, starting from a prepared bore, a finished bore having a predefinable nominal dimension, a predefinable target structure of the bore inner surface and a predefinable target position of the bore axis is generated, characterized by at least one power honing operation, in which using a honing tool by honing the bore with respect to the diameter of the bore an ablation of at least 0.5 mm is produced, wherein the power honing operation is performed as a position correcting honing operation such that the power honing operation, a displacement of the bore axis toward the target position, wherein a spindle distal end portion of the honing tool rotatably mounted on an inlet side of the bore opposite exit side in a counter-holder is, which is moved with an axial stroke of the honing tool with the honing tool.
  2. The method of claim 1, wherein no drilling operation is interposed between the preparation of the prepared bore and the power honing operation, wherein preferably during machining of a crankshaft bearing bore in an engine block, the power honing operation occurs immediately after assembling the crankshaft bearing bore forming parts of the engine block.
  3. Method according to claim 1 or 2, wherein at least phase-wise material with a specific removal rate of more than 13 mm 3 / s, in particular more than 20 mm 3 / s, is removed by machining during the power honing operation.
  4. Method according to one of the preceding claims, wherein the honing tool is rotated during the power honing at least in phases at a speed of more than 400 U / min, wherein the speed is preferably at least in phases more than 1000 U / min, in particular more than 1500 U / min, and / or wherein the honing tool during the power honing is moved at least in phases with a maximum lifting speed of more than 12 m / min, the maximum lifting speed preferably at least in phases more than 20 m / min, in particular between 30 m / min and 40 m / min is.
  5. A method according to any one of the preceding claims, wherein the workpiece is fixed in a workpiece position and the honing tool is inserted into the bore coaxial with the target position of the bore axis and moved within the bore.
  6. Method according to one of the preceding claims, wherein the honing tool with a spindle-side coupling structure rigidly coupled to a honing spindle or to a rigidly coupled to the honing spindle drive rod and is guided on at least one axially spaced from the coupling structure bearing point, wherein between the coupling structure and the bearing point at least one cutting group of the honing tool is arranged.
  7. A method as claimed in any one of the preceding claims, wherein the bore has a plurality of bore portions aligned in alignment with each other in series with each other, the honing tool being guided at at least one position between two adjacent bore portions and supported against radial forces.
  8. Device for fine machining a bore in a workpiece, in particular for fine machining a crankshaft bearing bore in a cylinder crankcase of an internal combustion engine, according to the method according to one of the preceding claims, with at least one honing spindle drivable by a spindle drive (US Pat. 110 ) to which a honing tool ( 170 ) is coupled or can be coupled, and a bearing device for guiding a lifting movement of the honing tool, wherein the honing tool is coupled directly or with the interposition of a rigid drive rod rigidly to the honing spindle or coupled and the bearing device ( 135 ) is arranged at an axial distance from a spindle-side coupling structure ( 172 ) arranged bearing of the honing tool on the honing tool such that between the coupling structure and the bearing at least one cutting group ( 178 ) of the honing tool, characterized in that a workpiece holder ( 140 ) is provided for the workpiece and the bearing means on one of the honing spindle ( 110 ) facing away from the workpiece holder an abutment ( 135 ) for rotatably supporting the honing tool ( 170 ), wherein the abutment is mitbewegbar in the lifting movement of the honing tool with the honing tool.
  9. Apparatus according to claim 8, wherein the apparatus is adapted to machine a workpiece, wherein the bore has a plurality of bore portions ( 462 . 463 . 464 ), which are arranged in alignment with each other in line and in mutual distance in series, wherein at least one tool storage ( 426 . 437 . 890 ) is provided for insertion into a space between two adjacent bore sections,
  10. Apparatus according to claim 9, wherein the tool storage ( 890 ) a machine-fixed fixable bearing element ( 891 ) and with respect to the bearing element freely rotatable, on or in the bearing element rotatably mounted guide element ( 892 ) with a guide opening ( 893 ) for passing the honing tool, wherein the rotatable guide element preferably at least one entrainment element ( 895 ), which is provided for engagement in a recess provided on the tool body of the honing tool.
  11. Device according to one of claims 8 to 10, wherein the honing tool has a plurality of cutting strips (16) distributed around a tool body ( 178 ) and a length of the cutting bars is more than three times, in particular more than four times the effective diameter of the honing tool.
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CN103447903B (en) * 2013-09-04 2015-09-09 潍柴动力(潍坊)再制造有限公司 The reproducing method of engine cylinder block assembly main bearing hole
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CN105382600A (en) * 2015-12-09 2016-03-09 重庆市钜铖机械有限公司 Drilling fixture for end face of cam shaft
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