EP3083137B1 - Method and grinding machine for measuring and producing a target outer contour of a workpiece by means of grinding - Google Patents

Description

The invention relates to a method for measuring and generating an outer contour of at least one region of a workpiece by grinding and a grinding machine for carrying out the method.
In-process measurements for the continuous measurement of workpiece areas directly during processing, ie in particular during grinding, with a corresponding adaptive control of the grinding process as a function of the current measured workpiece dimensions are known. In particular, in the grinding of shaft parts and in particular bearing points on crankshafts measuring devices, for example, the companies Marposs SpA or JENOPTIK Industrial Metrology Germany GmbH are used. From the WO 01/66306 A1 , Which represents the closest prior art to the subject matter of claims 1 and 13, a method for measuring and generating an outer target contour (r (p)) of at least a portion of a workpiece, in particular a crankshaft known, wherein in terms of dimensions and shape Longitudinal grinding or plunge grinding by means of a grinding wheel on a grinding center with CNC control for their relative to the longitudinal extent of a workpiece area to be grounded at right angles directed X-axis, in which an actual contour is measured on the workpiece; the measured values are transmitted to the CNC control and the CNC control is controlled in such a way that any deviations from the desired contour are corrected and the nominal contour of the respective workpiece area is adaptively ground on the basis of the measured values acquired for the respective measurement planes of a workpiece area.

That's how it is DE 694 13 041 T2 a sensor from Marposs SpA known for the control of linear sizes. The measuring device known for measuring inside diameters of bores as well as outside diameters has a movable probe in the form of a spherical element, wherein an additional element is provided, which transmits deflections to the spherical element. In this case, the workpiece is measured with respect to its diameter in a contact region on the outer or on the inner surface, which lies substantially in a plane perpendicular to the longitudinal direction of the component to be measured. In the known measuring device, the spherical member is in contact with a stopper surface on which it is movable in oblique direction, wherein the stopper surface is concave in cross-section, which serves as a seat for the spherical member and this leads in the oblique direction. The measuring plane of the respective diameter to be measured is defined as the reference position.
Furthermore, in DE 33 36 072 C2 described a sensing device for measuring linear dimensions, which has also been registered by the company Marposs SpA. Here too the measurement is carried out with the known probes for external dimensions as well as for internal dimensions in a plane perpendicular to the longitudinal axis of the finished finished to be measured Workpiece portion. A measurement of shape deviations such as roundness error is not described.

In the brochure MOVOLINE In-process measuring technology from Jenoptik, in-process measuring technology is used to measure the larger dimensions of machined workpiece areas including the continuous measurement of these dimensions for adaptive control of the grinding process depending on the measured workpiece parameters as well as the optional use of these measuring devices Control of the roundness described, the latter being measured at the end of the machining process (see there the measuring systems DF500 or DF700, page 15). In this known measuring system is also described to work for the determination of outer diameters with two measuring heads in the sense of an in-process measurement. However, the shape dimensions are also made after completion of grinding or a grinding process step, but not used for adaptive control.

For the particular in the grinding industry constantly increasing demands on the accuracy, for example in the production of crankshafts including their bearings, it is no longer necessary to pay very close attention to the achievement of the required nominal dimensions in the smallest possible tolerance range, but it is necessary form deviations, for example To minimize the roundness of the workpiece area to be ground, in particular a bearing point of a centric bearing of a crankshaft. This requirement exists above all in the production of high-precision shaft sections.

In the known technical embodiments described above, there is the problem that the measurements, in particular the diameter of the workpiece areas to be ground, preferably always take place in the center of the grinding wheel, which also corresponds approximately to the center of the bearing point to be ground or the workpiece area. The location of the measurement at a particular location is called a measurement track, i. in the case described, the measuring track is in the axial direction, seen in the grinding wheel width, in the center of the grinding wheel. If, for example, lubrication holes in the grinding area or the use of steady rests during grinding is provided, the measuring track is also arranged eccentrically, i. it is measured off-center.

If, in the known systems, a measurement of the roundness or the roundness error is carried out after the grinding, then at least the current workpiece can no longer be influenced. The known measuring systems described do not provide sufficiently accurate measurement results on the basis of which one obtains highly accurate grinding results could, if a workpiece area to be ground deviates from the cylindricity or if this area is intentionally conical or convex or concave, since the acquisition of the measured values takes place only in one measuring track.

The object of the present invention is therefore to provide a method and a grinding machine by means of which by means of an in-process measurement both the dimensions and the shape of a workpiece to be ground during grinding detected and the desired shape based on these measured values can be corrected adaptively.

This object is achieved by a method having the features according to claim 1 and by a grinding machine having the features according to claim 13. Advantageous developments are defined in the respective dependent claims.

According to the invention, the method is used to measure an outer nominal contour of at least one area of a workpiece, in particular a crankshaft, in terms of dimensions and shape and also to produce dimensions and shape by longitudinal or plunge grinding by means of a grinding wheel on a grinding center with CNC control. In the process, an actual contour is first measured on the workpiece or workpiece area. The measured values of the dimensions and the shape, in at least two spaced-apart, extending transversely to the longitudinal extent of the respective workpiece area, located in the grinding wheel engagement area measurement levels are detected by a measuring device. The at least two measurement planes are generated by a relative movement between the workpiece area and the measuring device in the Z-axis direction relative to the movement of the grinding wheel in the direction of its Z-axis. This means that on the one hand the measuring device is movable in the axial direction of the longitudinal extent of the workpiece area to be ground on this, with a fixed grinding wheel, but on the other hand it is also possible that the measuring device is fixed and the workpiece is moved relative to the measuring device. The grinding wheel itself can be moved in the Z-axis direction along the workpiece area to be ground; However, it is also possible to use a grinding wheel with a width that the entire workpiece area to be ground can be ground in the sense of a plunge grinding without moving the grinding wheel in its Z-axis direction. The measured values of the dimensions and the shape of the ground workpiece area at the at least two measurement levels are transmitted to the CNC controller. On the basis of these measured values, the CNC control is controlled in such a way that any deviations from the desired contour, namely with respect to dimension and shape, are corrected and the sol contour of the respective workpiece region is adaptively ground on the basis of the measured values acquired for the respective measurement planes of a workpiece region becomes. Adaptive grinding is to be understood here as meaning that both the dimensions and the shape of the workpiece area to be ground are measured permanently or at intervals and entered into the control device in the sense of an in-process measurement, wherein the control device is designed such that it opens Based on these measurements both in terms of dimensions and in terms of shape such as roundness of the workpiece section to be ground is adaptively deliverable. This ensures that the quality of the workpiece area to be ground in terms of dimensions and also shape, in particular roundness, is significantly better than that which can be produced with the known grinding and measuring methods.

With the method according to the invention, therefore, the measuring track is adjusted in the axial direction over the grinding wheel width during grinding, so that the entire outer contour can be detected during grinding and the corresponding measured values can be entered into the control device for the delivery of the grinding wheel, so that also the Form deviations can be permanently corrected, ie be automatically compensated.

The method according to the invention is also applicable, above all, to pendulum lifting grinding, which is used for grinding, in particular, the crank bearings of a crankshaft. The grinding of the rod bearings is now for the first time in an in-process measurement with respect to the diameter as well as the shape of the bearing as well as in terms of shape tolerances as well as the shape, for example, cylindricity, conicity or deviations thereof or a spherical or concave shape of the respective journal, and measured through the bearing width feasible. To achieve the highly accurate nominal contour, an adaptive grinding realized on the basis of the measured values determined in several measuring tracks is also used during grinding of the stroke bearings.

In a preferred embodiment, in which the measuring device moves in the Z-axis direction relative to the grinding workpiece, so the measuring device with respect to the width of the grinding wheel, i. in relation to the geometric longitudinal axis of the workpiece to be ground, move automatically. The number of measurement tracks or measurement planes to be measured on the workpiece to be ground depends on the required accuracy and also on the desired shape of the outer contour to be measured.

Preferably, the deviation of the shape, such as roundness, cylindricity, conicity, crowning and / or concavity, is measured by two measurement planes farthest on the workpiece area, and more preferably, the measurement planes are continuously adjusted over the entire measuring range. This has the advantage that for any measurement task and for each any desired contour, the number of measurement levels to be measured or their distance from each other can be set arbitrarily. For reliable determination of crowning or concavity at shaft sections at least measurements in three measurement planes are provided.

Further preferably, the measuring device is stationary on the wheelhead relative to this in the X direction and arranged movable relative to this in the Z direction and the wheelhead movable in the Z-axis direction, so that here also the respective desired measurement levels or measurement tracks individually and stepless each can be adjusted according to accuracy and to be ground target outer contour.

Preferably, the movement of the measuring device by means of an electric drive, which is preferably controlled freely programmable. With a freely programmable control, the measuring device and thus the flexibility of the method according to the invention obtains a high degree of freedom and forms the basis for the application to a wide variety of external target contours to be ground.

Preferably, however, it is also possible that the measuring device is moved hydraulically or pneumatically in the Z direction. The use of a hydraulic or pneumatic drive device for the movement of the measuring device or the use of a freely programmable electric drive depends on the particular application and on the envisaged budget for the machine on which the inventive method is realized.

Preferably, as is the case with in-process measurements, it is measured during grinding. Preferably, this in-process measurement is performed during finish grinding. However, it is also possible that for the purpose of measuring the grinding wheel feed is interrupted and continued after measuring the grinding process, wherein the grinding wheel remains in its holding position until the measuring process is completed. Furthermore, it is possible for the measured values in the at least two measuring planes to be detected only after finish grinding and for the measured contour of the workpiece to be evaluated in its entirety, and then the results for grinding the next workpiece optionally with a correction for the contour incorporated in the control by means of CNC control of the grinding wheel are taken into account.

Often it is necessary in particular for bearing journals that the desired outer contour slightly deviates from an ideal cylindrical shape. As a rule, this form deviation is determined by the technical and lubrication technology by the intended use of the component.

With such a relatively small deviation from cylindricity, this deviation is generated by pivoting the grinding wheel in a horizontal plane about a CNC-controlled axis. The horizontal plane runs horizontally to the central axis of the workpiece. With the method according to the invention, in such a case, in such a number of measurement planes in the axial longitudinal extent of the workpiece region to be ground, it is measured that the outer nominal shape can be determined with the required high accuracy and, accordingly, the grinding wheel via its CNC control for producing this outer -Sollform is controlled in terms of their delivery to the workpiece area. The desired shape of the workpiece area is usually ground by a grinding program entered into the CNC control, wherein as a result of the measurement of the outer target shape of the workpiece area an adaptive adjustment of the grinding program is made, which means that corrections or correction functions are entered into the grinding program be so that during grinding otherwise resulting or overlapping errors can be further reduced.

Preferably, it is also possible to produce the desired shape of the workpiece region to be ground by means of a grinding wheel previously dressed in accordance with the desired shape to be achieved with a dressing wheel and grinding the workpiece region in a corrected manner by re-dressing the grinding wheel. This means that the method according to the invention can also be applied to a dressing wheel, so that the corresponding accuracies in terms of dimensions and shape can be achieved on the workpiece area to be ground also by a regular high-precision dressing of the grinding wheel in a manner which in terms of accuracy with respect to known are significantly improved or increased.

Thus, with this method according to the invention, the cylindricity, conicity or a crowned or concave shape of a bearing, in particular a crankshaft over the bearing width already on the grinding machine during grinding can not only be measured exactly, but also directly by selective adaptive influence and correction via the grinding program also be corrected. In the known methods, it was necessary that the crankshaft first had to be measured externally for this purpose. On the finish-ground workpiece these deviations in shape could not be corrected without the bearing was then ground, for example, too small, so that the crankshaft broke.

This disadvantage is even stronger when the crankshafts have large dimensions, which is often the case with crankshafts for truck engines or stationary diesel engine units. Especially when grinding large crankshafts, the demands on the cycle time are included the production of crankshafts not critical to the extent critical for smaller components. As a result, increased measurements in just according to the invention several measurement planes are performed, which although the processing times slightly increased, but this contributes to the considerable increase in the quality of the finished component. After all, the price of this particular large crankshaft is already relatively high after prefabrication and is several hundred or several thousand euros. Thus, the method according to the invention becomes even more effective, the more expensive and complex the production of the blank in the processing steps before grinding. This is especially true for the production of special crankshafts with small batch sizes.

• Abrichten der Schleifscheibe hinsichtlich einer zu erzeugenden speziellen Zylinderform, Konizität, Balligkeit oder Konkavität;
• dem Vorsehen einer CNC-gesteuerten B-Achse durch Schwenken der Schleifscheibe in horizontaler Ebene zur Mittelachse der Kurbelwellenlängsachse, insbesondere für die Erzielung einer Zylinderform bzw. Konizität;
• durch Vorsehen einer so genannten CNC-gesteuerten "Mini-B-Achse" durch Schwenken der Schleifscheibe in horizontaler Ebene zur Mittelachse der Kurbelwellenlängsachse in geringen Schwenkwinkeln für eine geringe von der Zylinderform abweichende Konizität oder Balligkeit oder Konkavität (siehe dazu insbesondere die Anmeldung mit der Anmeldenummer WO 2012/126 840 A1 desselben Anmelders); und
• dem speziellen, auf das erfindungsgemäße Verfahren des Messens in mehreren Messspuren bzw. Messebenen angepassten Schleifprogramm.

According to the preferred embodiments of the method according to the invention, the high qualities and narrow dimensional and shape tolerances can be obtained for grinding components

• Dressing the grinding wheel with respect to a particular cylinder shape, taper, crown or concavity to be produced;
• the provision of a CNC-controlled B-axis by pivoting the grinding wheel in the horizontal plane to the central axis of the crankshaft longitudinal axis, in particular for achieving a cylindrical shape or conicity;
• by providing a so-called CNC-controlled "mini-B axis" by pivoting the grinding wheel in a horizontal plane to the central axis of the crankshaft longitudinal axis in small pivoting angles for a small deviating from the cylindrical shape conicity or concavity (see in particular the application with the application number WO 2012/126 840 A1 the same applicant); and
• the special, adapted to the inventive method of measuring in several measuring tracks or measurement levels grinding program.

According to a further aspect of the present invention, a grinding machine according to the invention is provided, on which the method according to one of claims 1 to 12 is carried out. This grinding machine according to the invention has a measuring device, by means of which dimensions and shape such as diameter and or roundness of workpiece areas of a rotating around a center workpiece, in particular a crankshaft, are measured and generated with a central longitudinal axis. This grinding machine has a mounted in a wheelhead grinding wheel, which grinds during grinding with simultaneous feed movement in the direction of its X-axis. In the usual way, the X-axis is understood to mean the movement of the grinding wheel at right angles, relative to the longitudinal extension of the workpiece region to be ground. The grinding machine according to the invention belonging measuring device is arranged on the wheelhead and designed such that a sensor to the workpiece area for installation is pivoted, wherein the measuring device or the actual measurement exporting probe or the probe element arranged transversely to the longitudinal axis of the workpiece area measuring planes, which in the direction of Workpiece longitudinal center axis can be arranged according to the movement of the measuring device or the probe in this direction for the purpose of measuring at any position. Of course, it is also possible that the measuring device is fixedly arranged, whereas a workpiece spine spanning the workpiece is movable in the Z-direction. By means of such a grinding machine according to the invention it is thus possible to measure the ground workpiece areas during grinding, in terms of their dimensions as well as their shape, and at the same time optionally deviations from the target contour adaptive, ie correcting the delivery of the grinding wheel, ie their Act on X-axis delivery. As a result, the accuracy of the ground workpiece is significantly increased.

Preferably, the measuring device or its sensor is in the form of two arranged in the manner of a prism measuring surfaces. During measurement, these measuring surfaces touch the workpiece area on the contact area at a defined distance from each other. The measuring surfaces are arranged on the legs of the prism, on each leg of the prism a measuring surface is provided. The actual probe element for measuring is arranged in the middle part of the prism between the measuring surfaces. The measuring device is moved by means of a hydraulic, pneumatic or electric drive to the contact area. Preferably, this is a CNC-controlled measuring device, which is arranged on the wheelhead, so that a defined investment position and thus highly accurate measurement can be realized.

The grinding wheel used for grinding the workpiece area preferably has a width which corresponds approximately to the length of the workpiece area. In such a constellation or such a wide grinding wheel, the grinding wheel grinds in its delivery the workpiece area to be ground quasi by means of plunge grinding, without the grinding of the respective shaft portion would require a feed movement of the grinding wheel in the direction of its Z-axis.

According to a further embodiment, the grinding wheel is formed with a width which is smaller than the axial length of the workpiece area to be ground, the grinding wheel in such a case along its axis of rotation over the axial longitudinal direction the grinding of the workpiece area performs a longitudinal grinding and thus is moved during grinding along its Z-axis.

Further preferably, the grinding machine has a measuring device designed in such a way that a conical, crowned or concave shape of the workpiece region can be determined by means of the measuring planes of the respective workpiece region, in particular cranked journal, on which a measured, and based on the measured values can be generated.

Figur 1:

eine prinzipielle Seitenansicht einer Anordnung zum Schleifen eines Hublagers beim Pendelhubschleifen mit einer Messvorrichtung zum Messen des Durchmessers eines Hublagerzapfens gemäß dem Stand der Technik;

Figur 2:

eine Teilansicht einer Anordnung gemäß Figur 1 an der Messstelle des Hublagerzapfens in vergrößerter Darstellung beim Schleifen und Messen an einem Lagerzapfen gemäß dem Stand der Technik;

Figur 3:

eine Teil-Vorderansicht auf den Schleifspindelstock beim Schleifen eines Hublagers einer Kurbelwelle mit einer Messvorrichtung gemäß der Erfindung;

Figur 4:

eine Teilschnittansicht mit einer Führungsschiene zur Verstellung der Messvorrichtung in Richtung einer ZM-Achse gemäß der Erfindung;

Figur 5:

eine Schnittdarstellung der erfindungsgemäßen Messvorrichtung entlang einer Schnittebene A gemäß Figur 4;

Figur 6:

eine Teilansicht einer Schleifscheibe im Eingriff an einer Lagerstelle einer Kurbelwelle mit prinzipieller Angabe zweier in Längsrichtung der Lagerstelle beabstandeter Messebenen gemäß der Erfindung;

Figur 7:

eine Teilansicht eines Lagerzapfens einer Kurbelwelle während des Schleifens mit einer Schleifscheibe mit einer geringeren Breite als die Länge des Zapfenbereiches und angegebenen unterschiedlichen, axial voneinander beabstandeten Messebenen;

Figur 8:

ein Hublagerzapfen einer Kurbelwelle mit angedeuteter konischer Sollkontur; und

Figur 9:

ein Hublagerzapfen mit einer balligen, konvexen sowie mit einer angedeuteten konkaven Außen-Sollkontur.

Further advantages, applications and specific embodiments will now be explained in detail with reference to the accompanying drawings. In the drawing show:

FIG. 1:

a schematic side view of an arrangement for grinding a stroke bearing in the pendulum stroke grinding with a measuring device for measuring the diameter of a stroke bearing pin according to the prior art;

FIG. 2:

a partial view of an arrangement according to FIG. 1 at the measuring point of the pin bearing pin in an enlarged view during grinding and measuring on a bearing pin according to the prior art;

FIG. 3:

a partial front view of the wheel spindle when grinding a crank bearing of a crankshaft with a measuring device according to the invention;

FIG. 4:

a partial sectional view with a guide rail for adjusting the measuring device in the direction of a ZM axis according to the invention;

FIG. 5:

a sectional view of the measuring device according to the invention along a sectional plane A according to FIG. 4 ;

FIG. 6:

a partial view of a grinding wheel in engagement with a bearing point of a crankshaft with a principle indication of two spaced apart in the longitudinal direction of the bearing measuring planes according to the invention;

FIG. 7:

a partial view of a journal of a crankshaft during grinding with a grinding wheel with a smaller width than the length of the pin portion and specified different axially spaced measuring planes;

FIG. 8:

a crankpin of a crankshaft with indicated conical target contour; and

FIG. 9:

a pintail with a convex, convex and with an indicated concave outer contour desired.

In FIG. 1 an arrangement is shown in a schematic representation, which shows the pendulum lifting of a stroke bearing pin 2 by means of a pendulum lifting a perform grinding wheel 5. A grinding headstock 4 carries at its upper area with respect to the grinding wheel 5 a measuring device 1, which consists of a in abutment position on the measured to be measured crankpins 2 of the crankshaft 3 measuring arm corresponding to the solid lines in a retracted position, in which is not measured, in dashed lines is movable. The grinding wheel 5 with its axis of rotation 13 can be controlled via a CNC-controlled X-axis controlled on the stroke bearing pin to be ground. The rotational axis 13 of the grinding wheel is also referred to as C-axis and is also CNC-controlled. The necessary for the realization of the movement in the X-axis direction elements and the workpiece headstock with its C-axis, which is not shown here separately, are constructed in a conventional manner on a machine bed, also not shown. The grinding takes place in the interpolating grinding process via respective adjustments of the CNC-controlled X and C axes.

This in FIG. 1 shown einschwenkbare measuring system 1 is arranged with its drive on the wheel spindle 4 and has an articulated arm, at the front end of a measuring head 7 is arranged. With the articulated arm of the measuring device 1 of the measuring head 7 can be adjusted to the outer contour of the illustrated pin bearing pin 2 for measuring its dimensions. During grinding at the grinding wheel engaging portion 8, the crankshaft 3 also rotates around its center 6, and the pendulum lifting grinding wheel 5 follows the eccentric movement of the crankpin 2 and remains in constant grinding engagement with it throughout the grinding operation. The measuring device 1 shown abuts against the contact area 9 with the measuring sensor 7 and can thus measure the actual diameter of the stroke bearing journal 2 by means of the feeler element 15. If it is not desired to measure, as is the case, for example, when a new crankshaft is loaded into or unloaded from the grinder, the measuring device with its articulated arm and probe is in a retracted position, indicated by dashed lines in the figure.

The measuring device 1 is arranged stationarily on the wheelhead with respect to its X-axis, so that during a movement of the grinding wheel 5 with the wheelhead 4 along the X-direction, the measuring device 1 also mitausführt this movement.

In FIG. 2 is an enlarged partial view of the engagement of the grinding wheel 5 at the grinding wheel engagement region 8 shown on the to be grounded crankpin 2, whose longitudinal axis is denoted by 14. By means of the grinding wheel 5, the outer nominal contour 10 of the pin bearing journal 2 is generated. During grinding, the measuring device 1 is applied with its measuring head 7 and its measuring surfaces 11 arranged thereon on the abutment region 9 of the crank journal 2. The measuring surfaces 11 form a prism, which applies to different diameter to be ground. Between the measuring surfaces 11, the actual measuring device is arranged, which is a linear measuring device and according to the diameter to be measured or the contour to be measured of the to be ground lifting bearing pin 2 in the direction of the double arrow shown is movable. The delivery of the grinding wheel 5 to the stroke bearing journal 2 is shown by the indicated X-axis. The prism-shaped measuring fork rests on the workpiece in a prism-shaped support by a predetermined bearing force with the two measuring surfaces 11 defined by support pins on the component to be measured, ie on its surface. The support pins are made of carbide or diamond coated material. The actual measuring device, which is arranged between the two support pins approximately in the middle of the V-shaped prism, is a probe, by means of which the measurement of the bearing point is made.

In FIG. 3 is a partial front view of the wheel spindle 4 during grinding of a crank pin 2 a crankshaft 3 shown. The crankshaft 3 is indicated by two truncated main bearings, two crank webs and a crank bearing 2 arranged between the two crank webs. The rotational movement of the crankshaft 3 is realized by the CNC-controlled C axis. The grinding wheel 5 with a width B is engaged with the pin bearing pin 2 and is shown during its grinding. The measuring device 1 is shown on the side of the stroke bearing journal 2 that is circumferentially offset from the engagement region 8 of the grinding wheel 5, which measuring device is set against the stroke bearing journal 2 with its measuring surfaces 11 for the purpose of measuring. The measuring device 1 is mounted on the wheelhead 4 by means of a feed carriage and performs the same feed movements of the X-axis of the grinding wheel 5, which is mounted on a grinding spindle. According to one exemplary embodiment of the invention, the measuring device 1 can be moved in the Z direction by means of a CNC-controlled separate ZM axis into a plurality of measuring planes on the stroke bearing journal 2 to be measured (indicated by the double arrow above the measuring device 1). At the bottom right in the figure is the indication of the Z-axis for the grinding wheel 5 and the wheel spindle 4. The movement of the measuring device 1 in the Z-axis direction is realized by the illustrated stand-alone CNC ZM axis.

In the usual way, the grinding wheel 5 is delivered via its X-axis, which is also CNC-controlled, to be driven to the crankpin 2. The Z-axis of the wheelhead 4 may be located either below the X-axis, in which case preferably a cross slide design (not shown) is provided, or below the grinding table, in which case the grinding table with associated grinding table structures such as the workhead and tailstock (not shown) is moved. These two embodiments are quite common in the design of grinding machines.

According to the invention, it is important that between the workpiece, i. the crankshaft 3, and the grinding wheel 5 is provided a relative movement in the direction of the Z-axis or ZM-axis. As a result, measurements are made in different measuring planes with the measuring device 1, so that the component to be measured can be measured accurately in several planes along its axis and also the complete outer nominal contour 10 can be measured, which is the case in measuring devices and systems according to the prior art so far not the case.

Out FIG. 3 is thus apparent that the measuring device 1 axially parallel to the axis of rotation 13 of the grinding wheel 5 during grinding, ie during the grinding cycle can be automatically moved to any number of spaced measuring planes which are perpendicular to the longitudinal axis 14 of the pin bearing pin 2. The direction for this movement is indicated by the designation "ZM".

Since the CNC-controlled ZM-axis is independent of the CNC-controlled Z-axis, the measuring device 1 in the direction of the ZM-axis, the measuring plane on the straight ground pin bearing pin 2 parallel to the axial direction of the grinding wheel 5 on the pin bearing pin 2 automatically during the Adjust grinding. It is thus possible with the measuring device 1 according to the invention, that carried out during grinding the measurements at the respective straight ground bearing, ie during the continuous grinding process, ie in an in-process measuring method, in terms of cylinder shape, taper, crown or concavity and the deliveries the grinding wheel 5 are also corrected by the grinding program during grinding. Thus, with the method according to the invention, highly accurate bearing points are produced because the results of the in-process measurement are entered into the control device in terms of size and shape of the bearing point to be measured, and a corrected outer nominal contour 10 is generated on the basis of these measured values. This results in a significantly higher quality of the ground workpiece areas, ie bearing points of the crankshaft.

In FIG. 4 is shown in a partial sectional view of a rail guide of the measuring device 1 along its ZM axis. The ZM axis is arranged perpendicular to the plane of the drawing. With the double arrow and "X" is indicated that the X-axis takes place via the movement of the wheelhead 4, because the measuring device 1 is fixedly mounted on this wheel spindle 4, thus mitausführt the movements of the wheelhead 4 along the X-axis. In FIG. 4 It is shown that the base plate of the measuring device 1 is mounted on a guide by means of guide rails 12 on the wheelhead 4. In the present case, a guide is shown, which consists of two guide rails 12 and is constructed in each case with backlash-biased ball or Rollenumlaufschuhen. In the middle between the guide rails 12, a final drive by means of a ball screw is shown in a simplified representation.

FIG. 5 shows a sectional view through the measuring device 1 along the in FIG. 4 The cutting plane is located below an unmarked adjusting plate which receives the first pivot bearing of the pivoting arm of the measuring device 1.

In FIG. 5 the two guide rails 12 are shown with the associated ball or Rollenumlaufschuhen in plan view. The ball or roller circulating shoes are firmly connected to the adjusting plate by a screw connection. In the middle between the guide rails 12 of the adjusting drive is shown, which in this case is a drive via a ball screw, not shown, which is mounted separately and is driven via a coupling with a CNC-controlled servo motor. Such a configuration of the displacement or movement of the measuring device 1 in its ZM-axis direction is stable and rigid enough, in conjunction with the CNC control, a highly accurate positioning of the measuring device 1 in any desired, depending on the surface shape of the ground journal tap planes arranged in a defined Automatically guarantee number during the grinding process.

In FIG. 6 is shown a crank journal 2 of a two cheeks indicated crankshaft 3, which is ground by means of a grinding wheel 5 with a width B. The width B of the grinding wheel 5 is so large that the length L of the stroke bearing pin 2 to be ground can be ground in the way of plunge grinding. Furthermore, the mutually parallel longitudinal axes 14 of the pin bearing journal 2 and the axis of rotation 13 of the grinding wheel 5 are shown. In the grinding wheel engagement region 8, the arrangement of three measuring planes of the measuring device, not shown, is shown schematically, wherein the average measuring plane between the two marked by the double arrow ZM outer Measuring levels, which limit the measuring range, is arranged. As a result of the adjustability of the measuring device 1 along the CNC-controlled ZM axis, displacement of the measuring plane in the entire region, which can be determined by the design of the ZM axis depending on the design and dimensioning, can be carried out continuously. The illustrated stroke bearing has on both sides of the actual stroke bearing journal 2 undercuts. However, a plunge grinding for generating the outer nominal contour 10 of the pin bearing journal 2 can also be effected in the way of plunge grinding in such a case, if instead of the reliefs transition radii are provided on both sides of the plan.

Also FIG. 7 shows a partially illustrated stroke bearing with a crankpins 2 between two partially illustrated cheeks of a crankshaft 3. The crankpins 2 with a crankpins L length is sanded by means of a grinding wheel 5 at the grinding wheel engagement area 8. The width B of the grinding wheel 5 is less than the stroke bearing journal length L, so that the grinding wheel 5 along its rotation axis 13, which runs parallel to the longitudinal axis 14 of the crank journal 2, by way of longitudinal grinding, the outer target contour 10 of the pin bearing pin 2 generates. By way of example, six different measurement planes running in the axial direction of the longitudinal axis 14 of the crankpin 2 are shown, two of which are identified by means of the double arrow indicated by the ZM. The grinding wheel 5 is thereby by longitudinal grinding from its left position, in FIG. 7 is shown, moved to its maximum right position, in which the grinding wheel 5 is shown in dashed lines. In principle, it is also possible, with a width B of the grinding wheel 5 as drawn, to produce the outer nominal contour 10 of the pin bearing journal 2 by two recess grinding operations, instead of the described longitudinal grinding. If sanding is carried out with at least two recess grinding operations, the bearing point must be ground by two or more puncture prongs, one after the other and next to each other. The different measuring levels can be arranged over the entire width of the stroke bearing and steplessly approached. The number of measurement planes in which a measuring operation is carried out during grinding depends on the accuracy of the external target shape 10 to be achieved as well as on the shape thereof.

In FIG. 8 is a lift bearing with a crankpin 2 between two partially illustrated cheeks of a crankshaft 3 shown, which has a Hubzapfenlänge L. The dashed lines are intended to illustrate what is to be understood by taper of a journal in the context of this application. On the one hand, the taper on the crankpins 2 is ground by a specially profiled or obliquely arranged grinding wheel, wherein, depending on the width of the grinding wheel or length of the journal bearing by means of plunge grinding or longitudinal grinding or Doppeleinstechschleifens the outer contour of the journal can be generated. By a corresponding number of measurement levels and executions of ongoing measurements during grinding, ie, performing a so-called in-process measurement, a highly accurate conical shape of a bearing pin can be ground without the end of the grinding, as may stand The technique is the case, when measuring after grinding should be found that the conical outer contour against the target contour to be achieved is too small and thus the entire crankshaft committee.

For reasons of load as well as for example for lubrication reasons, the shape of a crank pin 2 may also be spherical or concave. This is in FIG. 9 shown, wherein the solid lines represent the spherical shape of the crank pin 2 and the dashed form represents a concave shape. The stroke bearing journal 2 has in its transitions to the cheeks of the crankshaft 3 undercuts. With the aid of the measuring method according to the invention in conjunction with the grinding method, by means of which the measured values obtained in the process are continuously entered into the control for the infeed of the grinding wheel, it is thus possible to grind almost any desired outside contour contour 10 of a journal, ie also of a journal bearing journal 2, wherein a very high accuracy of the respective ground journal can be achieved.

LIST OF REFERENCE NUMBERS

1

measurement device

2

crankpins

3

crankshaft

4

Wheelhead

5

grinding wheel

6

Center of the crankshaft

7

probe

8th

Wheel engagement area

9

plant area

10

Target outside contour

11

measuring surfaces

12

guide rail

13

Rotation axis grinding wheel

14

Longitudinal axis of crankpins

15

scanning element

B

Grinding wheel width

L

Hublagerzapfenlänge

Claims (19)

1. Method for measuring and generating an external setpoint contour (10) of at least one region of a workpiece, in particular of a crankshaft (3), with regard to dimensions and shape by longitudinal grinding or plunge grinding by means of a grinding disc (5), which has an axis of rotation, on a grinding centre with CNC controller for the X axis of said grinding disc, which X axis is directed at right angles relative to the longitudinal extent of a workpiece region to be ground, in which method

   a) an actual contour on the workpiece is measured;

   b) measurement values of the dimensions and of the shape in at least two mutually spaced-apart measurement planes, which extend transversely with respect to the longitudinal extent of the respective workpiece region and which are situated in the grinding disc engagement region, are detected by means of a measurement device (1) during the grinding process;

   c) the measurement planes are generated by means of a relative movement between the workpiece region and the measurement device (1) in a Z axis direction, which is formed along the axis of rotation in the longitudinal direction of the workpiece region to be ground, relative to the movement of the grinding disc (5) in the direction of the Z axis during the grinding process;

   d) the measurement values are transmitted to the CNC controller, and

   e) the CNC controller is controlled such that any deviations from the setpoint contour are corrected, and the setpoint contour of the respective workpiece region (2) is ground in adaptive fashion on the basis of the measurement values detected for the respective measurement planes of a workpiece region.
2. Method according to Claim 1, in which the workpiece regions (2) are measured with regard to roundness, cylindricity, conicity, sphericity and/or concavity along the spacing between at least two measurement planes which are spaced apart at the workpiece region (2), wherein the measurement planes are adjusted in continuously variable fashion.
3. Method according to Claim 1 or 2, in which the workpiece is clamped so as to be positionally fixed with regard to its longitudinal axis (6), and the measurement device (1) is moved in the direction of the longitudinal axis (6) in the respective measurement plane.
4. Method according to one of Claims 1 to 3, in which the measurement device (1) is arranged on the grinding spindle stock (4) and is moved relative to the latter in the direction of the Z axis for the purposes of measurement in different measurement planes.
5. Method according to one of Claims 1 to 4, in which the movement of the measurement device (1) is performed by means of an electric drive which is controlled in freely programmable fashion.
6. Method according to one of Claims 1 to 4, in which the measurement device (1) is moved hydraulically or pneumatically in the Z direction.
7. Method according to one of Claims 1 to 6, in which measurement is performed during the grinding process, in particular during the finish grinding process.
8. Method according to one of Claims 1 to 6, in which measurement is performed during an interrupted grinding disc feed movement, and, during the measurement process, the grinding disc (5) remains in a holding position until the measurement has been performed.
9. Method according to Claim 8, in which the measurement values are detected after the finish grinding process, the measured contour of the workpiece is evaluated, and during the grinding of the next workpiece, a possibly required correction of the contour is performed by means of the CNC controller of the grinding disc (5).
10. Method according to one of Claims 1 to 9, in which the setpoint shape of the workpiece region to be ground is generated by pivoting of the grinding disc (5) in a horizontal plane about a CNC-controlled axis, wherein the plane lies horizontally with respect to the central axis of the workpiece.
11. Method according to one of Claims 1 to 10, in which the setpoint shape of the workpiece region is ground by means of a grinding program input into the CNC controller.
12. Method according to Claim 8 or 9, in which the setpoint shape of the workpiece region to be ground is generated by means of the grinding disc (5), which is dressed in advance in a manner corresponding to the setpoint shape by means of a dressing disc, and the workpiece region is ground in a corrected manner by means of redressing of the grinding disc.
13. Grinding machine for carrying out the method according to one of Claims 1 to 12, having a measurement device (1) for measuring dimensions and shape, such as roundness, of workpiece regions (2) of a region of a workpiece revolving around a centre, in particular of a crankshaft (3), having a central longitudinal axis, the grinding machine having:

    a) a grinding disc (5) which is mounted in a grinding spindle stock (4) and which, during the grinding process, performs grinding with a simultaneous feed movement in the direction of an X axis which is directed at a right angle relative to the longitudinal extent of a workpiece region to be ground,

    b) wherein the measurement device (1) is arranged on the grinding spindle stock (4) and is designed such that a measurement sensor (7) is movable such that it can be pivoted in in the direction of the workpiece central longitudinal axis onto, and so as to abut against, an abutment region (9), which is situated in the grinding disc engagement region (8), on the workpiece region (2) in freely programmable measurement planes which are arranged transversely with respect to the longitudinal axis (10) of the workpiece region (2) and which are formed during the grinding process,

    wherein the measurement planes are generated by means of a relative movement between the workpiece region and the measurement device (1) in a Z axis direction, which is formed along the axis of rotation in the longitudinal direction of the workpiece region to be ground, relative to the movement of the grinding disc (5) in the direction of the Z axis during the grinding process.
14. Grinding machine according to Claim 13, in which the measurement sensor (7) has two measurement surfaces (11) arranged in the manner of a prism, which measurement surfaces each make contact with the workpiece region (2) at the abutment region (9) during the measurement process.
15. Grinding machine according to Claim 13 or 14, in which the measurement device is displaceable hydraulically, pneumatically or electrically.
16. Grinding machine according to one of Claims 13 to 15, in which the measurement device (1) is displaceable in CNC-controlled fashion on the grinding spindle stock (4).
17. Grinding machine according to one of Claims 13 to 16, in which the grinding disc (5) has a width corresponding to the length of the workpiece region (2).
18. Grinding machine according to one of Claims 13 to 16, in which the grinding disc (5) has a width (B) smaller than the axial length (L) of the workpiece region (2), and said grinding disc performs longitudinal grinding along its axis of rotation (13) over the axial longitudinal direction of the workpiece longitudinal axis.
19. Grinding machine according to one of Claims 13 to 18, in which the measurement device (1) measures the dimensions of the respective workpiece region, in particular crankpin bearing journal, at such a number of measurement planes of said workpiece region that a conical, spherical or concave shape can be determined and can be generated on the basis of the measurement values.

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