EP2167277B1 - Grinding center and method for simultaneous grinding of a plurality of bearings and end-side surfaces of crankshafts - Google Patents

Abstract

A grinding center for the simultaneous grinding of a plurality of main and rod bearings and/or central and end-side sections of crankshafts includes first and second stations. Two main bearing grinding spindles, of which the first is movable only in the Z-direction and the second only insignificantly movable in the X-direction, are mounted on a common rod bearing-compound slide. In the final phase of grinding, a correction of variations in size between the two processed rod bearings occurs via a separated drive of the second rod bearing-grinding spindle in accordance with a size or roundness correction. The variations are detected by measuring devices. An inclined profiled grinding wheel is provided for the grinding of the end sections.

Description

The invention relates to a grinding center for grinding main and lifting bearings having crankshafts, wherein a plurality of main and stroke bearings and end surfaces, in particular a flange, are ground substantially simultaneously.

Such grinding centers are used for pre and / or fine grinding of crankshafts in high quantities. These are often crankshafts for four-cylinder in-line engines in the automotive industry, in which two stroke bearings are arranged in the same angular position with respect to the longitudinal axis of the crankshaft. These two stroke bearings are ground simultaneously to increase productivity (parallel to time). Such an approach is for example in the EP 1 044 764 A2 and the EP 1 088 621 A2 described.

For the main bearings of crankshafts, the simultaneous grinding of several bearings has been known for some time, eg from the US 3,487,588 , In this case, the grinding spindle for the main bearing on a number of grinding wheels, which is the same number of main bearings. The grinding wheels are on a common axis. A newer representation can be found in the DE 101 44 644 A1 ,

At the grinding center for crankshafts after the EP 1 044 764 A2 For the simultaneous grinding of two crank bearings of a crankshaft, a roughing wheel and a finish grinding wheel are used which are each fixedly mounted on a separate cross slide via the associated grinding spindle. The two cross slides are independent of each other in crankshaft longitudinal direction (Z-direction) movable and deliverable in the direction of the crankshaft (X-direction). By means of a corresponding control of the cross slides and grinding spindles, a simultaneous machining of two crank bearings in one clamping is possible, the one pilot bearing pre-ground and the other finished grinding. in this connection there is a continuous monitoring of the grinding process via associated measuring equipment.

In the EP 1 088 621 A2 a method and an apparatus for simultaneous grinding of at least two bearings of a crankshaft is described in the far-reaching constructive and operational conformity with that in the EP 1 044 764 A2 consists of grinding center shown. Both systems have in common that they each use their own cross slide for each of the two grinding spindles used. Each of these cross slides requires a separate control for the entire grinding process and a constant monitoring and correction in accordance with real-time data on the roundness and the size of the ground bearing determined by measuring heads. The construction of the grinding center with two separate cross slides - only for the machining of two bearings - requires a large space requirement and a considerable amount of components and associated controls.

In the WO2005 / 080048 A1 a machining machine for machining workpieces is described in which grinding and / or rotating devices are present. The grinding device has a profiled grinding wheel inclined with respect to the Z axis, by means of which the workpiece can be ground flat as well as ground externally. The workpiece is turned and ground in the same setup.

In the WO 2004/069472 A1 For example, a grinding center for grinding crankshafts is known which has main bearings, crank bearings and end surfaces. The grinding center has a first and a second grinding station, each of which is equipped with a grinding spindle with one or two grinding wheels for pre- or finish grinding of the main or stroke bearings. At least one of the grinding stations can also be provided with a further profiled grinding wheel whose grinding spindle is arranged at an angle to the grinding spindles for the main and lifting bearings. This further grinding wheel is preferably used for grinding end faces of the crankshafts. The disadvantage is in the in the WO 2004/069472 A1 described grinding station, that the grinding spindle is arranged with the profiled grinding wheel together with the other Schleispindel on a swivel headstock and must be swung on a relatively long way to the working position. This leads to an extension of the cycle time for processing.

In the WO 2005/000507 A1 is a machine tool for a machining described, in which two mutually parallel tool spindles in three directions are adjustable relative to each other. The adjustment in one or two axes takes place here by means of a rotatable and lockable eccentric sleeve. These are mechanically, electrically or hydraulically actuated via associated adjusting devices and allow exact adjustments in the range of a few millimeters.

Based on this prior art, it is an object of the invention to provide a grinding center for grinding crankshafts, in which the design complexity and space requirements is substantially reduced and with the simultaneous grinding of main bearings, crank bearings and end surfaces in a particularly fast and efficient Way with high quality is possible.

The solution to this problem is given by a grinding center with the features of claim 1.

Space requirements and structural complexity are advantageously already reduced in the grinding center according to the invention in that two stations for simultaneous (simultaneous) grinding of at least two camps are combined to form a grinding center. Together with the main bearings and centric circumferential parts of the journal-side and flange-side crankshaft end can be ground in the first station be, on the plan side and / or in diameter, by means of a relative to the Z-axis of the workpiece with respect to its axis of rotation inclined profiled grinding wheel; Preferably, this grinding wheel is arranged in the first station. Since all main bearings can be ground simultaneously in the first station, in contrast to the second station there is a time reserve that can be exploited. End-side surfaces, in particular those of the crankshaft flange, are ground at least temporarily parallel to the main and / or stroke bearings.

If both stations are arranged with the common axial direction of the crankshafts to be ground, the conversion of the crankshafts from one to the other station is also very simple. In addition, there are several advantages through the arrangement of two grinding spindles for machining stroke bearings on a common cross slide. These additional advantages are seen in particular in a simplification of the control of the grinding process and the reduction of the number of components and the space required.

The control of the common grinding of two stroke bearings is inventively such that the propulsion and the monitoring / correction of the removal and the concentricity of the ground bearings initially only via the control of the movements of the common stroke bearing cross slide. In this phase, the main removal of the grinding takes place for both stroke bearings. Only when the nominal dimensions are approximately reached, the first grinding spindle and the second grinding spindle are controlled differently in terms of movement. The first stroke bearing grinding spindle, which is rigidly connected to the stroke bearing cross slide with respect to the feed direction (X direction) of the grinding wheels, is further controlled via the control of the stroke bearing cross slide in accordance with dimensional and roundness values determined via a measuring device the required end setpoint values for the relevant grinding operation are achieved.

Preferably, the end flanges of the crankshaft are ground time-parallel to the main bearings, preferably finished ground. The designated grinding wheel is profiled and inclined with respect to the axis of rotation so inclined to the Z direction that the flat end surfaces and the cylindrical surfaces of the flange or the pin can be preferably ground in one operation.

The roundness values do not necessarily have to be measured at every stroke bearing. These correction values, after a measurement in the control system, can be detected and stored for a specific number of crankshafts until a further roundness measurement takes place.

Although the feed of the second stroke-bearing grinding spindle also follows the movement of the stroke-bearing cross slide in this phase, this movement is superimposed on another movement component in the X-direction. This further movement component serves for a differential correction of dimensional and / or roundness deviations which occur on the two simultaneously processed stroke bearings. Such deviations can be caused for example by different wear of the two grinding wheels. Another major reason for this deviation is that the waves distort slightly during grinding as stresses in the material can be released. They are detected according to the invention by continuous determination of the dimensions and the roundness of the two stroke bearings, including corresponding measuring devices are provided for each stroke bearing.

The differences to be corrected between the two crank bearings are only slight in the final phase of grinding; According to experience, they are in the range of hundredths or thousandths of a millimeter. Therefore, only a small adjustment range for the movement of the second stroke bearing grinding spindle is sufficient. This area advantageously only needs to cover about +/- 0.2 mm.

In accordance with claim 2, a mutual adjustability of the two stroke bearing grinding spindles in the axial direction is prescribed on the stroke bearing cross slide. As a result, adaptation to different axial distances of the stroke bearing pairs to be grounded is made possible, as is adjustment to different types of crankshaft. Appropriately, the axial adjustability is included in the machine control and triggered automatically. In general, the second stroke bearing grinding spindle, which is arranged in an adjustable manner anyway in the radial direction, will also be axially adjustable, but the reverse design is also conceivable in that the second stroke bearing grinding spindle is axially fixed on the stroke bearing cross slide while the first stroke bearing grinding spindle used for axial adjustment on the rotary bearing cross slide.

An embodiment of the drive for the movement of the one (second) grinding spindle in the dimensional and roundness correction axis is preferred in accordance with the invention Claim 3 as NC axis, as such can be easily integrated into the CNC machine control.

An advantage also results in an embodiment of the grinding cell according to claim 4, wherein for the processing in the first station also a grinding of the plan sides of the cheeks of the crankshaft, which usually form the transition from the bearing to the actual cheek is provided. As a result, the time T _{1 can} be exploited and adapted so that in the corresponding time T ₂ two pairs of crank bearings are processed.

The grinding of the face sides of the cheeks at the bearing points of the crankshafts can be done either by displacing the main bearing cross slide in the Z direction or by axially displacing the main bearing grinding wheels on the main bearing grinding spindle, cf. However, it is also possible to offset the crankshaft in the axial direction relative to the main bearing grinding wheels, see. Claim 7.

If the processing times T ₁ and T ₂ for the main or lifting bearings are matched according to claim 6, results in a particularly efficient operation of the grinding center, since then the placement or discharge of the two stations can be performed simultaneously and thus eliminates waiting times.

According to claim 9, the pendulum lifting method is preferably used for grinding the stroke bearings, which results in simplifications for the bearing and the drive of the crankshaft for the machining of the stroke bearings. Here, the ground in the first station main bearings can readily be used for storage of the crankshaft in the second station, whereby a high accuracy in the processing of the stroke bearings can be achieved. Furthermore, the inventive arrangement and control of the two stroke bearing grinding spindles on only one cross slide, that only a single feed carriage is present. The main movement of the two grinding wheels, namely the Pendelhubbewegung and the feed, are thus effected by a single feed carriage. This leads to a substantial simplification of the control over the prior art, since during the vast majority of processing only one feed carriage is to be monitored and controlled. The different control of the movement of the two grinding spindles in the final phase of grinding ensures that any deviations between the two stroke bearings are detected and compensated, so that at the end both stroke bearings are ground to the specified size.

The clamping and the rotational drive of the crankshafts via specially designed main bearing or stroke bearing headstocks or corresponding tailstocks according to claim 10 allows a particularly flexible use of the grinding center. A clamping of the crankshaft with the possibility of rotation about the main bearing longitudinal axis or the longitudinal axis of the roller bearing allows the choice between a normal grinding or the pendulum lifting for the Hublagerschleifen.

A continuous measurement of the dimensions and the roundness of the bearing in process according to claim 11 allows a timely detection and highly accurate correction of the grinding result.

Preferably, the grinding wheel is arranged for grinding the flange with respect to the side of the crankshaft on which the grinding wheels of the lifting and main bearings are arranged. However, it is also possible according to a further preferred embodiment that all grinding wheels are arranged on one side of the crankshaft. The grinding wheel for grinding the flange and / or the pin is provided either in the first station for grinding the main bearings or in the second station for grinding the stroke bearings or in each of the two stations.

With a grinding center according to the invention, of course, in addition to four-cylinder crankshafts, other crankshafts can also be ground if they each have two crank bearings mounted in the same angular position on the crankshaft. Similarly, the machining of camshafts is possible if they each have at least two main bearings and two arranged in the same angular position cams.

The invention also relates to a method for grinding the main and stroke bearings and / or centric parts of crankshafts according to claim 14. Embodiments of this method are listed in subclaims.

In the method according to the invention, which is realized in particular by means of a grinding center according to claim 1, the end faces of the flange or the pin of the crankshaft are at least partially ground time parallel to their main and / or stroke bearings.

• Fig. 1 eine schematische Draufsicht auf ein als Schleifzelle ausgebildetes Schleifzentrum nach der Erfindung;
• Fig. 2 eine schematische Draufsicht auf die erste Station der Schleifzelle, die zur Bearbeitung der Hauptlager einer Kurbelwelle dient;
• Fig. 3 eine schematische Draufsicht auf die zweite Station der Schleifzelle, die zur Bearbeitung der Hublager eingesetzt wird;
• Fig. 4 die Einspannung der Kurbelwelle in der ersten Station der Schleifzelle;
• Fig. 5 Einzelheiten der Einspannung der Kurbelwelle in der zweiten Station der Schleifzelle;
• Fig. 6 die Anordnung einer Messeinrichtung für das Maß und die Rundheit eines zu bearbeitenden Lagers in der zweiten Station;
• Fig. 7 ein Schnitt durch eine Schleifzelle nach der Erfindung gemäß dem Schnitt C-C in Fig. 1;
• Fig. 8 eine schematische Ansicht der ersten Station der Schleifzelle mit gegenüber den Hauptlagern-Schleifscheiben angeordneter profilierter Schleifscheibe für den Flansch;
• Fig. 9 eine Ansicht gemäß Fig. 8, jedoch mit Anordnung der profilierten Schleifscheibe auf der Seite der Hauptlager-Schleifscheiben; und
• Fig. 10 eine schematische Ansicht der zweiten Station der Schleifzelle mit gegenüber den Hublager-Schleifscheiben angeordneter profilierter Schleifscheibe für den Flansch.

In the following, the grinding center and the method according to the invention are explained in more detail with reference to the exemplary embodiments illustrated in the drawings. Show it:

• Fig. 1 a schematic plan view of a designed as a grinding cell grinding center according to the invention;
• Fig. 2 a schematic plan view of the first station of the grinding cell, which is used to process the main bearing of a crankshaft;
• Fig. 3 a schematic plan view of the second station of the grinding cell, which is used for processing the stroke bearings;
• Fig. 4 the clamping of the crankshaft in the first station of the grinding cell;
• Fig. 5 Details of the clamping of the crankshaft in the second station of the grinding cell;
• Fig. 6 the arrangement of a measuring device for the dimension and the roundness of a bearing to be processed in the second station;
• Fig. 7 a section through a grinding cell according to the invention according to the section CC in Fig. 1 ;
• Fig. 8 a schematic view of the first station of the grinding cell with respect to the main bearing grinding wheels arranged profiled grinding wheel for the flange;
• Fig. 9 a view according to Fig. 8 but with the profiled grinding wheel on the side of the main bearing grinding wheels; and
• Fig. 10 a schematic view of the second station of the grinding cell with respect to the Hublager grinding wheels arranged profiled grinding wheel for the flange.

In the Fig. 1 a grinding center designed as a grinding 1 grinding center is shown in plan view. This grinding cell has a common machine bed 2, on which two stations 3, 4 are arranged for machining crankshafts 22 by grinding. The stations 3, 4 have a common grinding table 5, on which respective holding devices and drives for the crankshafts 22 are present. The grinding cell usually also has a machine hood and loading and unloading devices for the supply and removal of the crankshafts 22 and for their transport from the first station 3 to the second station 4. These are however in Fig. 1 not shown, as well as not the CNC control device with input keyboard and hydraulic and / or pneumatic supply facilities.

The first station 3 of the grinding cell 1, which in Fig. 2 is shown individually, serves to grind the main bearing 23 of the crankshaft 22. For reasons of clarity, the most important functional parts of the first station 3 are therefore provided with the additional designation "Hauptlager-". The main bearings 23 ( Figure 4 ) are ground by means of a plurality of main bearing grinding wheels 10, which are arranged on a main bearing grinding spindle 9. The main bearing grinding spindle 9 is in turn attached to a main bearing cross slide 6, the CNC controlled in the Z direction, which corresponds to the crankshaft longitudinal axis 29, and in the X direction, which allows a delivery in the direction perpendicular to the crankshaft longitudinal axis 29 , is movable. Guideways or slide rails on which the main bearing cross slide 6 is moved in the Z direction are not visible, because they are covered by covers 16. The crankshaft 22 to be machined is clamped between a main bearing workpiece headstock 7 and a main bearing tailstock 8, as shown in FIG Fig. 4 is shown more clearly, and is in accordance with the representation of Fig. 2 set in rotation by the main bearing headstock 7. In the first station 3, at least two main bearings 23 of the crankshaft 22 are roughed or ground at the same time, for which a time T _{1 is} required.

The second station 4 of the grinding cell 1, which in Fig. 3 is shown individually, is used to edit the crank bearings 24 to 27 of the crankshaft 22, wherein in each case two stroke bearings 24 to 27, which are in the same angular position with respect to the crankshaft longitudinal axis 29, are ground simultaneously. The time required for grinding all four stroke bearings 24 to 27 is T ₂ . For reasons of clarity, the most important functional parts of the second station 4 are provided with the additional designation "stroke bearing".

Also in the second station 4, the crankshaft 22 to be ground is clamped centrally, ie the common longitudinal axis of the two-sided clamping devices is identical to the longitudinal axis 29 of the crankshaft 22, which is defined by its main bearing 23. As the Figures 3 and 5 can be seen, the crankshaft 22 is clamped in the second station 4 at its outer main bearings 23 which have been ground in the first station 3. As a result, an exact reference of the lift bearings 24 to 27 is made to the main bearings 23 of the crankshaft.

For clamping is in accordance with the Fig. 3 On both sides of the crankshaft 22 each have a stroke bearing workpiece headstock 12, 13 is provided. The chucks 31 of these pin bearing work spindle heads 12, 13 are provided with support shells and are driven by a respective C1 or C2 axis, which rotate absolutely synchronously. The crankshaft 22 can in the second Station 4 but also be taken between tips and is then at least driven only on one side by a lifting bearing workpiece headstock 12, the chuck is provided with floating jaws 33 and causes a compensating radial backlash-free rotary drive. The alignment of the crankshaft 22 then takes place through their centers on the centering tips.

The shape of the receptacle of the crankshaft 22 in the second station 4 can be varied and optimized depending on the specific individual case.

In both stations 3 and 4, the crankshaft 22 can be supported by one or more self-centering steady rests.

In the second station, a stroke bearing cross slide 11 is provided which is movable in the direction of the mutually perpendicular axes Z2 and X2, ie parallel to the crankshaft longitudinal axis 29 and perpendicular thereto. The stroke bearing cross slide 11 carries a first stroke bearing grinding spindle 14 and a second stroke bearing grinding spindle 15. From this, the first stroke bearing grinding spindle 14 in the direction perpendicular to the crankshaft longitudinal axis 29 is fixedly connected to the stroke bearing cross slide 11. By contrast, the second stroke-bearing grinding spindle 15 is arranged movably on the stroke-bearing cross slide 11 in the direction perpendicular to the crankshaft longitudinal axis 29. Their movement is controlled in accordance with a dimensional or roundness error obtained from in-process measurement during grinding. For this purpose, in-process measuring heads 19 of a measuring device 20 ( FIG. Fig. 6 ) measured the diameter of the pairs to be grounded stroke bearings 24, 27 and 25, 26 continuously during grinding.

Each of the two crank-bearing grinding spindles 14, 15 carries a crank-bearing grinding wheel 17, 18, the axial distance from each other must correspond to each other the distance of the pairs to be grounded crank bearings 14 to 17. For this purpose, the two stroke-bearing grinding spindles 14, 15 in its axial direction, ie in the direction of the axis of rotation of their crank-bearing grinding wheels 17, 18, on the stroke bearing cross slide 11 against each other to be moved. The axial distance between the pin bearing grinding spindles and grinding wheels must be adjusted each time a crankshaft of a different type is to be ground or, for a given crankshaft, there is a pair of pinion bearings at a different distance from the grinding. In this respect, the change in the distance must be included in the overall control of the grinding process. In this case, the first stroke bearing grinding spindle 14 or the second stroke bearing grinding spindle 15 in the direction of its longitudinal axis on the stroke bearing cross slide 11 be arranged adjustable.

Fig. 5 makes particularly clearly recognize a peculiarity of crankshafts 22 for four-cylinder inline engines: the two outer stroke bearings 24 and 27 have a common angular position with respect to the rotational and longitudinal axis 29 of the crankshaft 22 and also the two inner stroke bearings 25 and 26, wherein the angular position of the two stroke bearing pairs 24 and 27 on the one hand and 25 and 26 on the other hand is different.

This peculiarity is used for the economic operation of the grinding center according to the invention. With the two stroke bearing grinding wheels 17 and 18, the two stroke bearings 24, 27 and 25, 26 are each ground simultaneously, the word "simultaneously" also being used for the terms encountered in grinding technology "time-parallel" or "simultaneously". In each case, this means that the grinding process takes place in approximately the same time, but not that it must be finished at exactly the same time. The second stroke bearing is often finished only after the first finished by z. B. is still a residual allowance of 0.02 mm ablate.

Fig. 6 shows the arrangement of a measuring device 20 for continuously measuring the roundness and the dimensions of a stroke bearing in the second station 4 by means of a measuring head 19. The measuring head 19 comes during grinding in abutment against the stroke bearing to be monitored 24-27 and continuously generates signals with respect to the dimensions and / or the roundness of the stroke bearing 24-27, which are evaluated by the CNC control and used to generate control commands for the drives of the stroke bearing cross slide 11 and / or the Maß or roundness correction axis 44. In the Fig. 6 Dashed position of the measuring device 20 corresponds to a retracted position, which occupies the measuring device 20 approximately during a dressing operation and / or during the part handling of the pin bearing grinding wheels 17, 18.

In Fig. 7 is a schematic side view of the first station 3 of the grinding cell 1 according to the section CC in Fig.1 shown.

At the beginning of the stroke bearing grinding in the second station 4, the mutual axial distance between the two stroke bearing grinding wheels 17, 18 is set, for example, to the distance of the stroke bearings 24 and 27. Thereafter, the grinding of these stroke bearings 24, 27 begins in the CNC controlled Pendelhubverfahren. For this purpose, first the two stroke-bearing grinding spindles 14, 15 are moved together perpendicular to the crankshaft longitudinal axis 29; The second stroke bearing grinding spindle 15 remains immovable relative to the stroke bearing cross slide 11. This applies to the coarse or rough grinding phase. However, it is measured at each of the stroke bearings 24, 27 during grinding of the diameter just reached and determines the roundness. With the approach to the finished dimension in the phase of fine grinding, the movement of the second grinding spindle 15 is decoupled from that of the stroke bearing cross slide 11. The stroke bearing cross slide 11 is moved in accordance with the measurement at the stroke bearing 24 in the sense of a dimensional or roundness correction axis 44, by means of the first stroke bearing grinding spindle 14 finally the final dimension and the required roundness of the stroke bearing 24 can be achieved. At the same time, the second stroke-bearing grinding spindle 27 carries out correction movements with respect to the stroke-bearing cross slide 11 in accordance with the separate measurement on the stroke bearing 27, insofar as the measurements on the stroke bearing 27 deviate from those of the stroke bearing 24. These deviations result from the continuous measurement at both stroke bearings 24 and 27. The machine control computer analyzes the measurement results and forms corresponding correction and control signals for driving the second stroke-bearing grinding spindle 15.

The second stroke-bearing grinding spindle 15 naturally needs to be movable relative to the stroke-bearing cross slide 11 only to a small extent in the direction of the X-axis. An adjustment path that is advantageous in practice may, for example, be in the range of +/- 0.2 mm. The grinding center can be set so that the grinding time T _{1 is} equal to the grinding time T ₂ . Two of the main bearings 23 are then ground at about the same time as a pair 24, 27 or 25, 26 of the rod bearings.

Subsequently, the stroke bearing cross slide 11 is moved back, the distance between the two stroke bearing grinding spindles 14, 15 set from each other to the distance of the middle stroke bearings 25, 26, and the grinding cycle begins again.

In Fig. 8 is a schematic view of the first station of the grinding cell shown in a simplified representation, in which in the first station, the Mehrlagerschleifen the main bearing 23 of the crankshaft 22 by means of main bearing grinding wheels 10 is performed. The main bearing grinding wheels 10 grind in the first station 3, the main bearing 23. If the flat surfaces of the cheeks of the crankshaft 22, which point to the respective main bearing pin, are ground, the spindle with the main bearing grinding wheels axially moved to the crankshaft 22. However, it is also possible that the crankshaft 22 is moved along its axis of rotation relative to the main grinding wheels 10. In contrast to the main bearing grinding wheels 10, a profiled grinding wheel 45 is arranged on a spindle 46 inclined to the Z axis, ie to the spindle axis of the main bearing grinding wheels 10. The grinding wheel 45 is thereby profiled and arranged with respect to its angle to the Z-axis so that at the same time the flat end faces as well as the cylindrical surfaces of the flange 47 of the crankshaft 22 can be ground. The grinding wheel 45 is deliverable along the feed axis X.

In Fig. 9 is a view according to Fig. 8 shown, in which, in contrast to the arrangement according to Fig. 8 the profiled grinding wheel 45 is arranged with its spindle 46 on the same side of the crankshaft 22 as the main bearing grinding wheels 10. With the profiled grinding wheel 45, the end faces 48, namely the flat faces as well as the cylindrical surfaces of the flange ground in a single operation, the profiled grinding wheel 45 along its feed axis X can be delivered.

According to this embodiment, the main bearing grinding wheels 10 are arranged on a common spindle and grind the main bearings between the respective cheeks 49 of the crankshaft 22.

Fig. 10 shows a schematic view of the second station 4 of the grinding cell with respect to the roller bearing grinding wheels 17, 18 arranged profiled grinding wheel 45 for grinding the cylindrical and flat surfaces 48 of the flange 47 of the crankshaft 22. The profiled grinding wheel 45 with its spindle 46 is along its Zustellachse X deliverable and grinds the flange 47 in one operation. The profiled grinding wheel 45 is arranged opposite the crank-bearing grinding wheels 17, 18 in order to avoid any collision between the grinding wheels or to secure a simultaneous machining of the respective working surfaces. The stroke bearing grinding wheels 17, 18 with their respective spindle 14, 15 thereby grind the respective stroke bearings between the cheeks 49 in the pendulum stroke grinding process.

LIST OF REFERENCE NUMBERS

1

grinding cell

2

machine bed

3

first stop

4

second station

5

grinding table

6

Main bearing compound slide

7

Main bearing Workhead

8th

Main bearing tailstock

9

Main bearing grinding spindle

10

Main bearing grinding wheels

11

Pin bearing compound slide

12

Pin bearing workpiece headstock

13

Pin bearing workpiece headstock

14

first stroke bearing grinding spindle

15

second stroke bearing grinding spindle

16

cover

17

first stroke bearing grinding wheel

18

second stroke bearing grinding wheel

19

probe

20

measuring device

22

crankshaft

23

main bearing

24

pin bearings

25

pin bearings

26

pin bearings

27

pin bearings

28

plan page

29

Crankshaft axis

30

Pin bearing longitudinal axis

31

chuck

32

bearing shells

33

jaws

34

(Centering) peaks

41

Z-axis

42

X axis

43

axis of rotation

44

Dimensional and roundness correction axis

45

profiled grinding wheel for flange

46

grinding spindle

47

flange

48

end surfaces

49

cheek

Claims (19)

1. Grinding center that is for grinding crankshafts (22) having main bearings (23), pin bearings (24, - 27), and end-side surfaces (48), and that has

   - a first station (3) for grinding the main bearings (23), and

   - a second station (4) for grinding the pin bearings (24 - 27), and

   - a profiled grinding wheel (45) that is driven by means of a grinding spindle (46) arranged at an angle to the grinding spindles (9 and 14, 15) of the main bearings (23) and pin bearings (23 and 24 - 27),
   characterized

   - in that a group of main bearing grinding wheels (10) is arranged on a main bearing grinding spindle (9), arranged on a main bearing compound slide rest (6), such that a number of main bearings (23) that equals the number of main bearing grinding wheels (10) are ground time-parallel in a time T₁;

   - in that in the second station two pin bearing grinding wheels (17, 18) grind two pin bearings (24 - 27) on the crankshaft (22) by pairs in a time T₂; and

   - with their respective pin bearing grinding spindle (14, 15) are borne on a pin bearing compound slide rest (11) such that the first pin bearing grinding spindle (14) is arranged location-fast on the pin bearing compound slide rest (11) in the adjusting direction (X axis) and the second pin bearing grinding spindle (15) can be slightly displaced in the adjusting direction (X axis) relative to the first pin bearing grinding spindle (14) only in the sense of a dimension or roundness correction axis (44); and

   - in that the end-side surfaces of the crankshaft (22) can be ground by means of the profiled grinding wheel (46).
2. Grinding center in accordance with claim 1 in which the two pin bearing grinding spindles (14, 15) disposed on the pin bearing compound slide rest (11) can be displaced in the axial direction (Z2 axis) relative to one another.
3. Grinding center in accordance with claim 1 or 2 in which the second pin bearing grinding spindle (15) in the second station (4) can be adjusted by means of an NC axis that is effective in narrow limits for dimension and/or roundness correction, regardless of the movement of the pin bearing compound slide (11) towards the crankshaft 22.
4. Grinding center in accordance with one of claims 1 through 3, in which the main bearing grindings wheels (10) of the main bearing grinding spindle (9) in the first station (3) can be adjusted radially for grinding the main bearings (23) and can be displaced axially for grinding planar sides (28) of cheeks (49) on the crankshaft (22).
5. Grinding center in accordance with claim 4, in which the axial offset of the main bearing grinding wheels (10) occurs using the main bearing compound slide rest (6).
6. Grinding center in accordance with claim 4, in which the axial offset of the main bearing grinding wheels (10) occurs in that the main bearing grinding wheels (10) are arranged axially displaceable on the main bearing grinding spindle (9).
7. Grinding center in accordance with one of claims 1 through 3, in which, for grinding its planar sides (28) of cheeks (49), the crankshaft (22) is axially displaceable in the crankshaft longitudinal direction by means of the main bearing grinding wheels (10).
8. Grinding center in accordance with one of claims 1 through 7, in which T₁ is approximately equal to T₂.
9. Grinding center in accordance with one of claims 1 through 8, in which the pin bearing compound slide rest (11) is embodied such that a pendulum liftingmovement of the pin bearing grinding wheels (17, 18) can be generated.
10. Grinding center in accordance with one of claims 1 through 9, in which the first station (3) and the second station (4) each has a workpiece headstock (7, 12, 13) and a tailstock (8) and each workpiece headstock (7, 12, 13) and tailstocks (8) for the first and second station (3 or 4) are embodied such that the crankshaft (22) that has a main bearing longitudinal axis (29) and at least one pin bearing longitudinal axis (30) can be rotated about the main bearing longitudinal axis (29).
11. Grinding center in accordance with one of claims 1 through 10, in which a measuring device (20) for continuously measuring dimensions and roundness is provided that supplies a signal for controlling the movement of the pin bearing grinding spindle (14 or 15) in the adjusting axis (X axis) or in the dimensional and roundness correction axis (44).
12. Grinding center in accordance with one of claims 1 through 11, in which the grinding wheel (45), for grinding the end-side surfaces (48), has profiling such that an end-side flange (47) and/or pin on the crankshaft (22) can be ground with its axial and radial surfaces, and is arranged on a side of the crankshaft (22) that is opposite the side of the main bearing grinding wheels (10) or pin bearing grinding wheels (17, 18).
13. Grinding center in accordance with one of claims 1 through 11, in which the grinding wheel (45) for grinding an end-side flange (47) and/or pin on the crankshaft (22) with its axial and radial surfaces by means of the profiling is arranged on the side of the main bearing grinding wheels or pin bearing grinding wheels.
14. Method for grinding main bearings (23) and/or center sections and pin bearings (24 through 27) and end-side surfaces (48) of crankshafts (22) in a grinding cell that has two stations (3, 4), having the following method steps:

    a) in the first station (3), the main bearings (23) on the crankshaft (22) and/or center sections are ground with a set of main bearing grinding wheels (10) that are disposed on a common shaft of a main bearing grinding spindle (9);

    b) the crankshaft (22) is moved into the second station (4);

    c) in the second station (4), two pin bearings (24 and 27 or 25, 26), that have the same angular position relative to the rotational axis of the crankshaft (22) are ground at the same time by two pin bearing grinding wheels (17, 18);

    d) the adjusting movement for each of the two pin bearing grinding wheels (17, 18) disposed on pin bearing grinding spindles (14, 15) being arranged on a pin bearing compound slide rest (11), is individually computer-controlled, whereas the first pin bearing grinding wheel (17) is arranged location-fast in the adjusting direction (X axis) on the pin bearing compound slide rest (11) and is adjusted therewith, while the adjusting movement for the second pin bearing grinding wheel (18) relative to the first pin bearing grinding wheel (17) being made only according to a deviation from the adjusting movement of the first pin bearing grinding wheel (17);

    e) two crankshafts are always machined simultaneously in the grinding cell, the grinding time T₁ in the first station (3) being approximately the same as the grinding time T₂ in the second station (4); at least one of the end-side surfaces (48) is ground time-parallel, at least in part, to the main bearings and/or pin bearings.
15. Method in accordance with claim 14 in which the second pin bearing grinding spindle (15) with the second pin bearing grinding wheel (18) can be adjusted by means of an NC axis that is effective in narrow limits for dimension and/or roundness correction.
16. Method in accordance with claim 14 or 15, in which the main bearing grinding wheels (10) of the main bearing grinding spindle (9) are adjusted radially for grinding the main bearings (23) and are displaced axially for grinding planar sides (28) of cheeks (49) on the crankshaft (22).
17. Method in accordance with claim 16, in which the main bearing grinding wheels (10) are axially displaced in that the main bearing compound slide (6) is axially displaced.
18. Method in accordance with claim 16, in which the main bearing grinding wheels (10) are axially displaced in that they are axially displaced on the main bearing grinding spindle (9).
19. Method in accordance with claim 14 or 15, in which the planar sides (28) of the cheeks (49) on the crankshaft (22) are ground by means of the main bearing grinding wheels (10) in that the crankshaft (22) is axially displaced.

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