EP0997229A1 - Method and apparatusfor finishing cylindrical workpieces - Google Patents

Abstract

The fine machining machine-tool , especially band finishing appliance has at least one support element (10,11) for directly supporting it on the workpiece surface (1). At least two separately operated pressure elements (19,20) positioned in a staggered formation in a peripheral direction are supported on one support element. The pressure elements press the fine machining tool against the workpiece surface.

Description

The invention relates to a method and an apparatus for fine machining of essentially cylindrical workpiece surfaces, especially workpiece outer surfaces.

The increasing performance increase of internal combustion engines through higher compression and faster speeds i.a. the demand for wear reduction of bearings, to get better running qualities. For this it is for example known to be essentially cylindrical or axially slightly curved main bearing and pin bearing of crankshafts or camshafts after grinding an additional one Undergo finishing treatment to the Surface according to structure, roughness and percentage of load further refine. This is what they have in particular External honing and band finishing proven. When honing as an abrasive finishing agent honing stones or diamond strips used to the relative to the finishing agent rotating and short-stroke axially moving workpiece surface be pressed. A belt is used for belt finishing or polishing tape used as a finishing agent. A form-fitting pressure element that itself is not subject to wear, the sanding belt presses over a suitable wrap angle to the rotating and axially oscillating workpiece surface.

Numerous suggestions have already been made, such as the quality of the machined workpiece surface can be improved. One from the German patent DE 30 08 606 known device for external honing of eccentrically rotating crankshaft crank pin has one Rotary drive for the crankshaft to be machined and one of the orbital revolving crankshaft crank pin Beam with two beam halves, which are above support members Support directly on the workpiece surface and with large Force can be pressed against this. One of the beam halves is used excluding the support, while the other half of the beam has a honing tool that supports itself press a support arm against the surface to be machined can and driven oscillatingly via a vibratory drive is. To improve the surface quality, it is proposed the halves of the carrier are adjustable in height relative to each other to train them so that they can move towards the Have the machined workpiece set. The device brings very good processing results. For one usually required multi-stage machining with honing and The carrier must be fully honed to replace the honing tool be opened. Then, if necessary, a new one Height adjustment may be required. The procedure until it is reached a desired surface quality can therefore be time consuming.

The invention has for its object a method and propose a device of the type mentioned that it enable a desired surface quality quickly and to achieve reliably, especially with orbital circumferential workpiece surfaces.

The invention proposes a method for solving this problem according to claim 1 and a device according to claim 11.

According to the invention, at least one is directly connected to the Supporting member supporting the workpiece surface on the workpiece surface pressed. There will be at least two in Circumferential direction of the workpiece surface are supported directly or indirectly on a support member, independently operable pressure elements for Pressing on fine processing agents, especially sanding belts, provided on the workpiece surface. It will be one Relative movement of workpiece and finishing tool around a machining axis running coaxially with the workpiece surface generated, which preferably a short-stroke relative movement is superimposed in the axial direction. The pressure elements are operated in such a way that none of the pressure elements, one pressure element or several pressure elements Press the finishing agent onto the workpiece surface.

This process, in which both honing stones or the like, as well as sanding belt as a finishing agent either can be used alternatively or in combination through a high variability of the process control, whereby practically every required surface quality quickly and can be reliably achieved. Usually with that large force pressing of support organs against the Workpiece surface can be achieved that on the Finishing agent acting pressure, which by a itself on the support member or on a support member firmly connected part of the device supporting pressing element is generated, not by dynamic additional forces is influenced, as in particular with eccentrically rotating Workpiece sections, such as crankshaft crank pins, occur. Due to a non-uniform course of the dynamic Forces during a workpiece rotation can be without corresponding support elements on the workpiece surface zones with different contact pressure for the fine processing agent arise, and thus also different sizes Deductions. Through the support on the workpiece surface these inertia-related dynamic additional forces of the support members or from the support members Carriers added so that the necessary for processing, force to be applied by the pressure elements dynamic additional forces remains unaffected. That is also at higher workpiece speeds, which ensures a fast Editing are advantageous, for example, without additional effort without active compensation of the additional forces mechanical or electronic master waves, an even one Material removal guaranteed on the workpiece circumference.

By providing several in the same axial area more effective, but in the circumferential direction of the workpiece surface staggered, independently operable The removal characteristics of the pressure elements are very variable adjustable. For example, it is possible that at least two different, preferably independent pressing elements that can be actuated from one another according to type and / or Grain or removal rate of different fine processing agents pressed simultaneously or alternately, which means that one previously not easily possible per circulation Mixed processing is made possible. In particular, it is possible that without interrupting the relative movement of the workpiece and finishing agents and / or without lifting off Support organs from the workpiece first by a first one Pressed a first fine machining means is that the first pressure element is then relieved of pressure, is withdrawn in particular and that thereafter by a second pressing element a second fine machining means is pressed, preferably another, in particular has a finer grain than the first finishing agent. It is possible pre-processing and finishing to achieve a workpiece in one operation without the device for changing fine machining means opened or the editing process in another way must be interrupted.

It is possible that a pressure element during the finishing or relative movement between pressing phases at times from the finishing agent or, on the pressure element firmly attached fine machining agent, from the workpiece surface is lifted off. In this way, for example Use of liquid processing aids, such as honing oil, achieved a better rinsing of the finishing agent be obtained, making it easier to cut longer remains and higher stock removal rates can be achieved. Furthermore can the free-rinse effects known in conventional processes be greatly reduced, e.g. in the area of lubrication holes in the workpiece surface a more intense Flushing occurs, which results in locally higher erosion and thus leads to form errors. During a phase with lifted pressing element can be assigned to this Fine machining agents advantageously also at least partially by other finishing agents, especially unused ones Finishing agents of the same type, replaced especially by retightening the finishing tape.

In a further training it can be provided that at at least one pressure element, preferably at least two independently operable pressure elements, Finishing agent, especially sanding belt, with a contact pressure varying in the axial direction of the workpiece and / or with a removal rate that varies in the axial direction is pressed. The variation is advantageously continuous or stepless, which means that the finished workpiece surface bumps running in the circumferential direction how grooves or steps can be avoided. The variation can be generated by e.g. Abrasive belt with in axial Pressed in the direction of varying elastic compliance becomes. A varying contact pressure in one direction Processing section offers the possibility, for example an undesired taper in a crankshaft bearing increased removal in the area of larger cross-section quickly and reliably eliminate or other deviations from a desired, for example cylindrical ideal shape remove. On the other hand, it also becomes possible, for example to produce a desired crowning of a bearing section, by in the edge areas of the Machining section with a larger contact pressure or higher Material removal rate is worked as in between Middle range. To create a desired crown it may be so, for example, that by at least one Pressing element fine processing means, such as sanding belt, is pressed in such a way that the contact pressure and / or the Material removal rate from a central area of the machining section to axial edge areas of the machining section, preferably continuous and / or symmetrical to Middle area increases or it can be used, for example, for reduction an undesirable crown so that the Contact pressure and / or the removal rate from the central area the edge areas preferably continuously and / or symmetrically decreases towards the central area.

With further training it is possible that at least one Pressing element with a through during the fine machining a pressure control can be specified, continuously or discontinuously changing contact pressure is applied, which is particularly hydraulic, but possibly also piezoelectric, can be generated electromechanically and / or pneumatically. It has proven to be particularly advantageous if with at least one pressure element during finishing pulsating contact pressure is applied, the pressure curve for example sinusoidal, rectangular or can be sawtooth-shaped and possibly the pulse frequency, e.g. can be between 2 and 100 pressing phases per revolution, can be customized. Preferably several or all pressing elements simultaneously with pulsating Contact pressure operated. A pulsating pressure can, if necessary, even without complete pressure relief better rinsing of the finishing agent can be used.

Another advantageous processing variant stands out characterized in that all pressure elements with rotating workpiece so relieved of pressure, in particular lifted off that only support elements are supported on the workpiece surface. Experiments on the impact of the support elements on the surface quality of the machined workpieces shown that this "idling" without pressing, material-removing, fine processing agents roughness tips the machined surface a little smoothed can, so that an even lower Ra value and a higher Load share can be achieved without measurable changes the macro shape of the processed area.

In a preferred development it is provided that the Shape and / or surface condition of the processed Workpiece surface during the relative movement by means of preferably emitting at least one sensor signal contactlessly operating sensor device is detected and that the contact pressure in at least one pressure element Dependence on the sensor signals is controlled. By the Use of such an in-process measurement control through which for example the level and / or the distribution of contact pressures at different points along the scope of processing can be controlled independently, for example the roundness profile of a Workpiece recorded and evaluated in this way be that at the relative high points of the profile Fine machining agent pressed on with higher contact pressure is considered at rock bottom. This also allows long-wave Correct roundness error. As an actuator such a measurement-dependent contact pressure control is suitable a pressure element particularly well, as this as an adjusting element has a much smaller moving mass than, for example an entire print arm of a band finish or Honing machine and because of the contact pressure without any consideration the dynamic additional forces derived via the support member can be varied.

The measurement control offers in connection with the support Another great advantage directly on the workpiece. At the Measurement-controlled processing becomes conventional when it is reached Target dimension of the machining process canceled in that the respective device opened and thus the finishing agent is peeled off the surface. When editing of eccentrically rotating bearings, such as crank pins, however, this means that the workpiece is stopped first must be opened before the device can be opened. At the invention, however, the processing process for one finished axial section can be finished by that the assigned pressure elements are relieved of pressure or be lifted off while associated support members continue to the workpiece surface remain pressed so that the device can follow the eccentric circumferential section. In this way it is e.g. possible when editing a crankshaft for each axial machining section separate processing when the target dimension is reached cancel while continuing in other places becomes.

A device suitable for carrying out the method has at least one for direct support on the workpiece surface trained support member, at least two in Circumferential direction of the workpiece arranged offset to itself a support member directly or indirectly, separately or independently operable pressing elements for Pressing fine machining agent onto the workpiece surface and means for generating a relative movement between Workpiece and finishing tool to be coaxial with the Machining axis, the workpiece surface preferably a short-stroke relative movement in the axial direction is superimposed.

Although a single support may be sufficient, one has preferred embodiment several, preferably evenly support members distributed around the circumference, each of which assigned at least one, preferably only one pressure element is. This allows a particularly uniform Achieve distribution of forces during machining. Is preferred an embodiment with two diametrically in operation Machining axis opposite, essentially identical in shape and preferably essentially mirror-symmetrical can be arranged to a mirror plane of the device Support organs. These can be on a common, two-armed Carrier device may be arranged, for example for a workpiece change, can be swiveled open.

A support member can extend over one or more support surface sections Support directly on the workpiece. Prefers It is when it is at least one, preferably several, in particular interchangeable on one example cup-shaped body of the support member attached separately Support elements directly on the workpiece surface supports. Rollers or rollers can be used as supporting elements be provided. Support elements in the form of axial are preferred trending guide rails, which at least in one of the Surface section facing the workpiece surface a hard, wear-resistant material to make one permanent sliding contact to the workpiece surface under large To be able to withstand contact pressure. The one in touch with the workpiece surface that comes into contact with the support surface preferably smooth or essentially non-abrasive, so that material-removing processing essentially only takes place where fine machining means through the Pressing elements is pressed onto the workpiece surface. in the However, the area of support elements can possibly be a material-displacing one and / or possibly solidifying the surface Surface treatment can be effected or it may be that with detached cutting grains with a lapping machining loose grain is effected.

To achieve an even, controlled surface treatment is preferred for each support member at least one, preferably only one, the associated pressing element upstream and at least one, preferably only one support element downstream of the pressing element provided, the pressing element preferably symmetrical is arranged between the support elements. A support on both sides of the pressure element ensures a special anti-tip guide. It has proven itself when the support elements a circumferential angular distance of less than 150 ° and preferably have more than 90 °, with angular distances between 100 and 130 °, in particular of approximately 120 ° preferred are. These provide good support after all Directions without pinching the workpiece and offer on the other hand, enough space between the support areas Attach several if necessary offset in the circumferential direction and / or pressing elements which may be extended in the circumferential direction.

The fine processing agent can be in the form of a pressure element sintered or soldered coating. In an embodiment designed for band finishing The finishing tool is an abrasive belt that is relative is movable to the pressure element. The pressure element preferably forms a cylindrical section, for example Pressure surface of a predetermined shape, that of the desired one Shape of the finished workpiece surface is adjusted. It has proven particularly useful if the Pressure surface a circumferential angle of more than 60 °, preferably between 70 ° and 90 °, in particular about 80 °. A possible sanding belt wrap angle of more than 60 ° per pressing element makes it possible that short-wave Roundness errors of the workpiece automatically special can be effectively corrected.

In some processing situations, for example for Generation of a desired crowning of a bearing section or ideally to remove unwanted taper is essentially cylindrical workpiece sections at a preferred embodiment provided at least one Pressure element, preferably at least two of each other independently actuate pressure elements so that through them fine processing agents, especially sanding belts, preferably in the axial direction of the workpiece continuously varying contact pressure and / or with in Axial direction preferably continuously varying Removal rate can be pressed, preferably the Contact pressure symmetrical to a central area of a machining section varies. This can be done, for example achieved that at least one pressing element Has pressing surface, in which a substantially cylindrical Curvature in the circumferential direction is a curvature in the axial direction is superimposed. The curvature preferably runs here in the axial direction continuously and / or symmetrically to one axial central area of the pressure surface. If the curvature in Axial direction to the workpiece surface is convex and the Pressure surface, for example in the middle area of the workpiece surface closest is so in this area Removal performance compared to the axial edge areas extraordinary big. Conversely, with a pressure element Pressure surface in the axial direction also from the workpiece surface concave away, so that for example in the middle the distance between the workpiece surface and the pressing surface compared to the edge areas is large and there there is a correspondingly lower removal rate.

It can be particularly advantageous if several in Circumferential direction offset pressing elements the course of the Pressing surface in the axial direction is different, so that for example at least one pressure element with an in Axial direction convexly curved pressure surface and at least a pressure element that can be actuated independently of this a pressing surface curved concavely in the axial direction is provided. This makes it possible to press the a suitable pressure force profile in each case suitable pressing elements to be used in the axial direction. Not that required pressure element can be relieved of pressure, in particular be withdrawn.

A particularly gently varying pressure distribution can be thereby achieve that on a pressure element Pressure-forming layer made of elastically compressible Material is arranged, the layer thickness in the axial direction, preferably continuously and / or symmetrically to one Middle area of the machining section varies. It can So one in the axial direction corresponding to the layer thickness of the elastic material varying elastic resilience the pressure surface can be created. The layer that may an essentially cylindrical section-shaped pressing surface can form, ensures that the pressure distribution in the axial direction softened compared to a rigid pressure surface is so that disadvantageous peaks of contact pressure and / or removal performance can be avoided.

An advantageous tape guide that allows only that Pressing element, but not the support member by a Sanding belt is undermined, is associated with a preferred embodiment explained in more detail.

Some developments of the invention can also be applied to methods and devices may be advantageous in which in one Axial section only in a single circumferential section or several pressure elements are provided. They are in particular the pulsating pressing of at least one Pressing element, the temporary lifting of at least one Pressing element during the finishing, if necessary with it connected retraction of the sanding belt in a lifting phase and the described measurement-dependent control of the contact pressure and process variants thereby made possible, in particular the application of an axially varying contact pressure through a single pressing element and the selective termination of the machining process in individual axial machining sections continuing processing in other, not yet finished sections.

Fig. 1

eine teilweise geschnittene Axialansicht einer Bandfinishvorrichtung, die insbesondere bei der Feinbearbeitung von Kurbelwellen-Lagerflächen einsetzbar ist und

Fig. 2

eine Draufsicht auf die in Fig. 1 gezeigte Vorrichtung und

Fig. 3

eine schematische Draufsicht auf ein Kurbelwellenlager mit zwei diametral gegenüberliegenden Andrückelementen zur Aufbringung eines in Axialrichtung variierenden Anpreßdruckes auf ein Schleifband.

These and other features emerge from the description and the drawings in addition to the claims, the individual features being realized individually or in groups in the form of sub-combinations in one embodiment of the invention or in other fields and can represent advantageous embodiments. Embodiments of the invention are shown in the drawings. Show it:

Fig. 1

a partially sectioned axial view of a belt finishing device, which can be used in particular in the fine machining of crankshaft bearing surfaces and

Fig. 2

a plan view of the device shown in Fig. 1 and

Fig. 3

is a schematic plan view of a crankshaft bearing with two diametrically opposed pressure elements for applying a varying contact pressure in the axial direction on an abrasive belt.

In Fig. 1 is a cylindrical bearing journal 1 in axial view a crankshaft 4 to be seen by a not shown Rotary drive is rotated about its longitudinal axis such that the journal in the direction of arrow 2 around its central Longitudinal axis 3 rotates. If the journal 1 a with the Crankshaft longitudinal axis is coaxial main bearing journal, so is Longitudinal axis 3 essentially stationary. It is Bearing journal 1, however, around an eccentric to the crankshaft longitudinal axis arranged crankshaft crank pin, so is the Rotational movement in direction 2 an orbital movement of the entire Bearing pin around the parallel to axis 3 Crankshaft longitudinal axis superimposed.

The bearing journal 1 is made of two halves 5 and 6, respectively surrounded as the finishing arm support 7, the two arms 8 or 9. The two arms 8, 9 are not in one machine part shown pivotally mounted against each other. Via a hydraulic adjustment device, for example the two arms can be used to install the workpiece in the Device opened and then closed in this way be that the two arms shown the workpiece in the Include Kind. Via an axial vibratory drive, not shown can move the workpiece and / or the Carrier in the axial direction 3 a short-stroke axial relative movement between the entire support 7 and the workpiece 1 be generated. The entire device has to be used simultaneously Machining of main bearings and connecting rod bearings several in Axial direction arranged side by side, on a common Machine frame arranged finish units of the shown Art. The units are each very narrow (Fig. 2) to simultaneously process adjacent bearings can. Their dimensions are no longer than the length of the bearing plus the proportional (half) axial dimensions of the Crank webs.

Each support half 5 or 6 has one at the lower end of the assigned arm firmly screwed support member 10 or 11, which has the basic shape of a narrow in the axial direction 3, upright cuboid (see FIG. 2) with a workpiece 1 facing, circular segment-shaped recess 12 or 13 has, which is why a support member as a shell or Finish bowl is called. The two support halves 5, 6 or support members 10, 11 are in the working position shown mirror image of one containing the longitudinal axis 3 Plane of symmetry 14 arranged. They are relative in height fixed to each other and to achieve the highest machining accuracy together concentrically in one device been ground out.

Using the example of the right finishing bowl 11, the construction of a Supporting organ explained in more detail. A support member 11 has Area of its shell recess 13 two at a circumferential angle of approx. 120 ° to each other and at an angle of approx. 30 ° to the plane of symmetry 14 offset from this Guide strips 15, 16, each made of hard material, over the entire axial width of a support member extend and a substantially smooth, the workpiece contour have an adapted surface facing the workpiece. she ensure a jam-free, direct support of the support member across the workpiece surface in all directions to axis 3.

There is a middle between the wear-resistant guide strips Steel pressure element designed as a pressure shoe 20 provided that a cylindrically curved, the workpiece facing pressure surface 21 has a predetermined shape, that of the desired shape of the finished workpiece surface is adapted and over a circumferential angle of extends approx. 80 ° in compliance with the workpiece. The pressure surface can as in the example shown, essentially rigid, for example made of hard material, or also flexible be and for example from an elastically compressible Be piece of material formed. It can also be distributed over a large area elastic areas in addition to essentially rigid areas available. The pressure shoe 20 is seated in a recess 13 opened rectangular recess 17 of the support member 11 and is opposite this by means of two in cylindrical bores of the support member guided bolt 24 so linear movably guided that it is radial to the machining axis 3rd is movable. One the pressure shoe 20 in the direction of the pressing device pushing the workpiece or moving it away has two against the actuator or actuator Force of a spring 23 can be advanced in the direction of the workpiece, with the bolt identical hydraulic piston 24, which has a Hydraulic line 25 can be acted upon with fluid pressure. If the hydraulic pressure exceeds that applied by the spring Back pressure, so the pressure shoe becomes a workpiece the shoe is pushed forward when the hydraulic pressure is weaker lifted from the workpiece by the return spring 23, if necessary to he with his flat back on the one serving as a stop Because of the rectangular recess 17 receiving it.

Although one or more hydraulic to generate the contact pressure Actuating pistons are preferred, in principle also any other actuators, e.g. Piezo translators or solenoids can be used. Instead of the one shown, centrically acting actuator, one in the axial direction essentially even contact pressure of the shoe 20 causes to produce a varying in the axial direction Contact pressure of a pressure element also several in axially offset and / or attacking, Actuators which can be operated independently of one another are provided be that can generate different forces to the Height of material removal in the axial direction of the workpiece controlled influence. A corresponding pressure shoe can, for example, in its associated support member approximately tangential to the workpiece surface and perpendicular vertical to the longitudinal direction of the workpiece (axis 3) Pivot axis be pivotally mounted.

The diametrically opposite to the machining axis 3, mirror-image pressure shoe 19 is in an analogous manner Interplay between hydraulic pressure and spring force can be pressed or retractable, the control via one of the line 25 separate hydraulic line 26 regardless of the control of the shoe 20. This is an arrangement with two circumferentially offset by 180 °, separately or independently pressure elements that can be actuated from one another. At other embodiments are several per support element, in particular two pressure elements which can be actuated independently of one another intended. Also versions with only one support element or with more than two, for example three or four, especially evenly distributed around the workpiece circumference Support organs are possible.

The pressure shoe 20 presses in the illustration in FIG. 1 through a band guide 30 in the area of the pressure shoe guided grinding belt 31 to the workpiece surface. The Belt guide has a pair of im for each pressing element essentially tangential to the workpiece surface and perpendicular vertical to axis 3, also good in Fig. 2 recognizing oval tape guide openings 32, 33, which vertically from the vertical top or bottom of the support member into the area of the pressing element 20 extend and the workpiece side between pressure element and the associated guide strips 15 and 16 in the processing area flow out. The finish belt can pass through these recesses be guided in the shell so that the support strips 15, 16 can rest directly on the workpiece 1 and not be undermined by finishing tape. 2 it can be seen that that the axial width of the guide openings 32, 33rd is less than half as wide as the axial width of one Support element / pressure element combination or that of this width corresponding width of the sanding belt. By the triple dashed expansion of the grinding belt in the opening area is indicated that the band 31 in the oval areas where it passed through the openings is turned in a U-shape, with the smooth side outside and the grinding side is inside. In the area of with Distance above or below the band guide openings 32, 33 arranged, roller-shaped deflection elements 34, 35 and in The area of the pressing element 20 then has the band again taken up its straight, fully unfolded form in the axial direction. The course of the belt between the deflection rollers 34, 35 is essentially straight forward, which means trouble-free operation promotes.

In the embodiment shown, the two become independent pressure segments 19 which can be actuated hydraulically from one another, 20 of the same type of sanding belt. It is however possible, separate on the left and right Abrasive belts, especially with different grain sizes to use. This means that pre-machining and finishing is one Workpiece possible in one operation, for example first with the left pressure element 19 lifted off Coarse grain finish belt through the right pressure element 20 is pressed, then this is relieved of pressure, so that it is lifted off the finish belt by the force of the spring 23 is, and that then by the left pressure element 19th a fine grain sanding belt for finishing is pressed. Then, as already mentioned, also the left finishing belt can be relieved of pressure, so that at next rotating crankshaft only the guide rails still on the Slide off the workpiece surface and, if necessary, through it Smoothing and / or solidifying material displacement.

In particular, it is also possible with the pressure element lifted off retighten the assigned sanding belt without first stop the workpiece or open the device have to. This results in a considerable time advantage especially when machining hard workpieces and / or workpieces with large roundness errors makes where relatively much material has to be removed.

With the embodiment shown, the finishing process be carried out under measurement control. The Device at least one during the machining process operable, designed to emit sensor signals Sensor 40 for detecting the shape and / or surface quality the machined workpiece surface. The only one schematically shown and in the example on the right support member 11 attached sensor, which in the applied state of the finishing arm arranged in the region of the plane of symmetry 14 and radial is aligned to the surface, for example electrically, electromechanically, optically or with the help of fluid jets work. Even though the material surface is touching Sensors, such as buttons, are possible because of the Protection of the surface and the sensor without contact Sensors, for example air jet sensors, are preferred. A control device, not shown, can transmit the sensor signals process and at least one actuator, for example the hydraulic actuator 23, 24, preferably several or all actuators depending on the sensor signals head for. As a result, the advantages described above of measurement-controlled finishing achievable.

When measuring controlled finishing, several are in axial Distributed direction of the machined workpiece section Sensors or a corresponding linearly spatially resolving sensor used, can, for example, with that described above Execution of one with axially varying contact pressure pressurizable element, a targeted shape correction of the workpiece in axial section. It this can result in an undesired conicity in particular correct or create a desired crown.

The schematic top view in FIG. 3 shows an embodiment, which enables shape corrections to be made Perform workpiece in axial section. The diametrical Pressure elements 45, 46 are exactly like those of the embodiment 1 arranged and independent of each other radially displaceable on the workpiece surface or from this can be lifted off. The pressure elements are in the range of their workpiece-facing pressing surfaces 48, 49 provided, one between the pressing element and the workpiece surface carried out grinding belt 43, 44 to the workpiece surface to press. Each of the pressure elements has one essentially incompressible, rigid, half-shell-shaped metallic body 50, 51 with a workpiece facing Front surface 52, 53, on which a thin layer 54, 55 is made a relatively pressure-resistant, but slightly elastic compressible material, for example Vulcolan is applied.

The coated front surfaces 52, 53 are circumferential essentially curved in the shape of a cylindrical section, wherein this curvature in an axial direction parallel to axis 3 another curvature overlaid. The one shown above Pressure element 45 runs the continuous axial Curvature symmetrical to the axial central region 56 such that the front surface is concave from the workpiece in the axial direction is curved away and to the axial edge regions 57, 58 continuously approaches the workpiece surface. At the bottom Pressing element 46, the conditions are reversed and the Front surface 53 extends in the axial direction to the workpiece surface curved so that the front surface in the middle 59 is closer to the workpiece surface than to both axial Edge areas 60, 61. The layer thickness of the compressible The material varies axially for both pressure elements Direction continuous and is chosen so that the Workpiece or the abrasive belt facing pressure surfaces of the Layers essentially cylindrical, that is, in the axial direction just passed.

It is therefore one in the axial direction corresponding to the layer thickness varying elastic compliance of the pressure surface created. Through this geometry it can be achieved that the sanding belt through the upper pressure element with a Middle region 56 pressed relatively weaker contact pressure which is symmetrical to both axial edge regions 57, 58 increases continuously. When pressing this pressure element and simultaneous pressure relief or withdrawal of the opposite pressing element can have a certain crowning the machined surface at which the Slightly smaller diameter of the journal in the middle is larger than in the area near the crank webs. At Andrükken the sanding belt by means of the opposing pressure element 46, on the other hand, becomes a comparatively in the central region 59 generates large contact pressure, which is symmetrical to both Edge areas decreases continuously. As a result, a if present, crowning can be reduced.

The embodiment shown enables the described Correction of the shape of the machined workpiece surface a single linearly guided pressure element, without that this can be pivoted in the manner described above must be trained. This means that a shape correction is also possible relatively simple constructed processing devices possible. Since the corresponding due to the guide rails 15, 16 Back pressure is guaranteed even if according to this Invention feature only a pressing element in the cutting insert is or both with different pressure and thus Cutting effect can work manually or dimensionally or -regulates a shape correction with respect to the axial Contour can be reached. The pressure elements are thus on both sides individually or in a specific pressing force or used in a specific chronological order.

The interposition of an elastically flexible layer between the rigid body of the pressure element and the with the contact surface interacting with the grinding belt helps expedient to mitigate pressure force peaks and by the Shape of the rigid body specified pressure distribution to smooth out. In principle, the axial variation of the Contact pressure can be achieved even without elastic layers, for example by pressing them directly onto the sanding belt Pressure element body 50, 51, in which case their Front surfaces 52, 53 form the pressing surface. It can also sufficient, the axial middle or edge area of the pressure surfaces to be provided with a small step or shallow groove, whose depth can be very small. For example, one more or less clear "paragraph" in the machined workpiece surface generated to influence certain areas. Instead of one around the one occupied by the pressure surfaces Circumferential contour (groove, step, curvature or the like) can these only take up part of the circumference. So can e.g. at the ends of the pressing element lying in the circumferential direction Areas in the (axial) center or the edge opposite the cylindrical contact surface should be slightly recessed.

As a result, the processing area there is reduced or Machining pressure varies.

A different inclination of the pressure or Machining areas opposite the axis direction or a other asymmetry can be useful to consciously match Workpiece contours, e.g. Conicity, to generate or dismantle.

Possibly. it may be sufficient to use just one pressure element to train. Pressure elements with axially varying elastic compliance of the pressure surface can also Devices not according to the invention, e.g. with only one Pressure element, be advantageous.

The advantages made possible by the invention come entirely especially when machining eccentric rotating Workpiece surfaces, such as crankshaft crank pins, for carrying, where it is possible thanks to the support elements, the mass forces or derive inertial forces via the support members and completely decouple from the pressure elements that regardless of the support organs with usually clearly lower contact pressure than the support members against that machining workpiece can be pressed. Because the Pressure elements completely freed from management tasks are, they can in the variable manner described pressed or lifted off to get the desired machining result to achieve quickly and with high quality.

Claims (25)

Method for fine machining a substantially cylindrical workpiece surface, in particular the workpiece outer surface, of a workpiece with the following steps: Pressing at least one support member that is supported directly on the workpiece surface onto the workpiece surface; Provision of at least two pressing elements, which are arranged offset in the circumferential direction of the workpiece surface and are supported on a support member and can be actuated independently of one another, for pressing fine machining means, in particular grinding belt, onto the workpiece surface; Relative movement of workpiece and fine machining agent; Actuation of the pressing elements in such a way that either no pressing element, one pressing element or several pressing elements press fine machining means onto the workpiece surface. A method according to claim 1, characterized in that by at least two different, preferably pressing elements which can be actuated independently of one another Different types and / or removal characteristics Finishing agents are pressed, in particular Sanding belts of different grain sizes. A method according to claim 1 or 2, characterized in that that without interrupting the relative movement and / or without lifting the support member from the workpiece surface first by a first pressing element Finishing agent is pressed that after that first pressure element relieved of pressure, in particular is withdrawn and that thereafter by a second Pressing element a second finishing tool is pressed, preferably a finer removal characteristics has as the first finishing tool. Method according to one of the preceding claims, characterized in that at least one pressing element during finishing between pressing phases temporarily withdrawn while removing contact pressure is, preferably during a phase with withdrawn Pressing element the assigned finishing agent is replaced, in particular unused Sanding belt in the area of the pressure element brought. Method according to one of the preceding claims, characterized in that with at least one pressure element, preferably at least two of each other independently operable pressure elements, finishing tools, especially sanding belt, with an in Axial direction of the tool, preferably continuously, varying contact pressure and / or with in the axial direction, preferably continuously, varying Removal rate pressed against the workpiece surface is, preferably by at least one pressure element Fine machining agent is pressed in such a way that the contact pressure and / or the removal rate in axial direction is changed, in particular by one Middle area of the assigned processing section to axial edge areas of the machining section, preferably continuous and / or symmetrical to Midrange increases or decreases. A method according to claim 5, characterized in that an elastic resilience of a pressing surface of the Pressure element from a central area of the assigned Machining section to axial edge areas of the Processing section, preferably continuously and / or increases symmetrically to the central region or decreases. Method according to one of the preceding claims, characterized in that at least one pressing element for fine machining with changing contact pressure, especially pulsating contact pressure is, preferably several or all of the pressing elements be applied with pulsating contact pressure. Method according to one of the preceding claims, characterized in that while maintaining the Relative movement relieves all pressure elements in such a way withdrawn in particular that only that Support member pressed onto the workpiece surface is. Method according to one of the preceding claims, characterized in that shape and / or surface quality the machined workpiece surface during the relative movement by means of at least one Sensor device emitting sensor signals are detected and that the contact pressure of at least one pressure element controlled depending on the sensor signals , preferably at relative radial high points a pressing surface with a workpiece surface higher contact pressure is applied and / or relative radial low points a pressure element is relieved of pressure. Method according to one of the preceding claims, characterized in that with several in the axial direction of the workpiece successive machining sections with independently controllable values Pressure elements in at least one processing section Pressure elements when a predefinable one is reached Machining result relieved of pressure, in particular withdrawn while pressing elements in others Processing sections continue to be pressed. Device for finishing a substantially cylindrical workpiece surface, in particular workpiece outer surface a workpiece (1) by means of fine machining means, especially belt finishing device, with at least one for direct support on the workpiece surface trained support member (10, 11); at least two staggered in the circumferential direction, supported on a support member, from each other independently operable pressing elements (19, 20; 45, 46) for pressing on the finishing agent (31; 43, 44) to the workpiece surface and Means for generating a relative movement between Workpiece surface and finishing tools. Device according to claim 11, characterized in that several support members evenly distributed around the circumference (10, 11) are provided, preferably each support member at least one, preferably only one Pressure element (19, 20; 45, 46) is assigned and / or that two diametrically to a machining axis (3) opposite, preferably essentially mirror-symmetrical to a mirror plane (14) of the device support elements (10, 11) which can be arranged are provided. Device according to one of claims 11 or 12, characterized characterized in that a support member (10, 11) at least one, preferably several, in particular interchangeable support elements attachable to a body of the support member (15, 16) for direct support on the workpiece surface has, preferably the support elements are designed as axial guide strips (15, 16). Device according to one of claims 11 to 13, characterized characterized in that the support member, in particular that Support element (15, 16), one for contact with the support surface provided for the workpiece surface, which is essentially smooth and / or non-abrasive. Device according to one of claims 11 to 14, characterized characterized in that at least one, preferably only one in the circumferential direction the pressure element (19, 20; 45, 46) upstream and at least one, preferably only one the support element (15 or 16) is provided, preferably the support elements are arranged symmetrically to the pressing element. Device according to one of claims 11 to 15, characterized characterized in that the support areas, in particular Support elements (15, 16) of a support member Circumferential angular distance between 90 ° and 150 °, in particular between 100 ° and 130 °, preferably approx. Is 120 °. Device according to one of claims 11 to 16, characterized characterized in that a pressure element one, preferably cylindrically curved, pressing surface (21) firmly predefined form that the desired shape of the finished machined workpiece surface is adjusted and / or that a pressing element has a pressing surface (21; 48, 49), which has a circumferential angle of more than 60 °, preferably between 70 and 90 °, in particular approximately 80 ° includes and / or that a pressure element a rigid Pressing surface, in particular made of hard material, or a resilient pressure surface, in particular elastic material, or a pressure surface with a Combination of hard and resilient Areas. Device according to one of claims 11 to 17, characterized characterized in that at least one pressing element Front surface (52, 53) has one in the axial direction has a changing contour, especially with regard to diameter, effective working area and / or elasticity, wherein preferably the front surface (52, 53) one in substantially cylindrical curvature in the circumferential direction a course is superimposed, from one to the workpiece axis axis-parallel course deviates, especially one Forms curvature in the axial direction, where appropriate the curvature in the axial direction continuously and / or symmetrically to an axial central area of the front surface runs, preferably at least one Pressure element (46) the curvature in the axial direction Workpiece surface is convex and / or that at the curvature in at least one pressing element (45) Axial direction concave away from the workpiece surface runs. Device according to claim 18, characterized in that on the front surface (52, 53) a layer (54, 55) is made of resilient material, whose layer thickness in the axial direction, preferably continuous and / or symmetrical to a central area, varies, the layer preferably a essentially cylindrical pressure surface (48, 49) forms. Device according to one of claims 18 or 19, characterized characterized in that at least one pressure element (46) with a front surface convexly curved in the axial direction (53) and at least one independent of these actuatable pressing element (45) with one in the axial direction concave curved front surface (52) is provided. Device according to one of claims 11 to 20, characterized characterized in that a pressing element (19, 20) and / or in the associated support member (10, 11) is linearly movable, preferably such that it in a radial to the workpiece surface Direction is displaceable, and / or that the device at least one on the pressure element (20) and the assigned supporting member (21), preferably hydraulic, actuator (23, 24) for generation a relative movement of the pressing element and support member having. Device according to one of claims 11 to 22, characterized characterized in that the finishing agent at least an abrasive belt (31; 43, 44), the is movable relative to the pressing element. Device according to one of claims 11 to 22, characterized characterized in that for guiding the grinding belt (31) in one or from the area of a pressure element (20) Band guide (30) is provided, the band guide opening (32, 33), which in the circumferential direction between a Pressure element (20) and associated support areas, in particular support elements (15, 16) are arranged, preferably a tape guide opening (32, 33) in the essentially tangential to the cylindrical workpiece surface runs and / or that one, preferably oval, Band guide opening has an axial diameter that is less than an axial width of an associated one Pressure element and / or grinding belt. Device according to one of claims 11 to 23, characterized characterized in that they have at least one during the Relative movement operable to deliver sensor signals trained, preferably working without contact Sensor unit (40) for detecting the shape and / or Surface quality of the machined workpiece surface has, preferably the device one designed to process the sensor signal Control device through which at least one Actuator (23, 24) for a pressure element depending can be controlled by the sensor signal. Device according to one of claims 11 to 24, characterized characterized in that an axial movement device for Generation of a short-stroke oscillating axial relative movement between workpiece and one with at least a support element provided pressing element is provided is.

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