EP1427568B1 - Method and device for grinding central bearing positions on crankshafts - Google Patents

Description

The present invention relates to a device and a procedure for grinding centric bearings of crankshafts (see, for example, FR-A-1 487 669).

For carrying out the grinding of centric bearings or main bearings of crankshafts in mass production are, among other things, various possibilities to disposal.

Thus, the centric bearing points, for example, by means of individual grinding wheels be finished, but with a significantly higher grinding time goes hand in hand, since each main warehouse is processed individually. In addition, one is relatively complicated machine design needed to provide the flexibility for a to provide such a grinding process.

In addition, it is known, but not widely used in mass production, this Perform bearings on the crankshafts by means of the so-called "centerless" grinding.

The method most widely used in terms of mass production concerns the so-called multi-bearing grinding, in which several grinding wheels of a grinding spindle simultaneously engaged with the crankshaft at said locations of the respective Main camp come. The machines used for this purpose are Well known and have such a structure that on a machine bed a feed unit by means of a grinding spindle and a dressing device is constructed. The dressing device is preferably linear in direction delivered to an axis transverse to the main axis or center axis of the Rotation of the crankshaft runs. In the front area of such a grinding machine is arranged a sanding table, which either fixed on the machine bed is constructed or by means of a CNC axis in the direction of an axis which is transverse to Zustellachse and parallel to the axis of rotation runs, can be moved. On This grinding table is made up of a workpiece headstock and a tailstock. wherein the workpiece headstock includes the workpiece spindle. The workpiece spindle is known to be the inclusion of a chuck or a Driver for the crankshaft. The tailstock is also on the grinding table constructed and manually to adjust different lengths of the crankshaft displaceable. A tailstock quill can be used to load and unload the crankshaft automatically advanced and retracted, as is conventional Cylindrical grinding machines is well known.

For the clamping of the crankshaft, which is done on the headstock side, are offered the possibilities of either a floating entrainment system or of centrically exciting chucks. By means of a motor, the workpiece headstock and thus the crankshaft rotated. The tailstock quill is provided with a corresponding counter-tip, which is generally referred to as so-called. standing tip is executed. Between the workpiece headstock and the Tailstock is then inserted between the respective tips of the crankshaft their centers, thereby ensuring that the central axes the workpiece spindle on the one hand and the tailstock quill on the other hand with the central Axis or rotation axis of the crankshaft is exactly aligned.

For a precise monitoring of the grinding process, the workpiece is during the grinding by means of two measuring devices automatically in real time and measured Corrected the machine accordingly.

In the described Mehrlagerschleifverfahren are generally corundum grinding wheels, especially in crankshaft production, widely used. These Machines are characterized by being in the grinding wheel diameter have a wear amount of about 1100 to 600 mm. It is assumed, that every 20 to 30 ground crankshafts must be dressed and the dressing amount is on the order of about 0.03 mm.

In the method of multi-bearing grinding, it is advantageously possible centric bearings or main bearings to grind, the lateral undercuts have, i. No plan pages are ground here. In addition, it is it also possible to have main bearings with lateral radius transitions to this plan side and the plan side of this main bearing with a height of about 4 to 5 mm mitschleleifen.

The grinding of such main bearings with lateral radius transitions and possible plan pages proves to be considerably more difficult, since this is the procedure with regard to the grinding technology used more critical behaves.

Moreover, it is with the method of multi-bearing grinding on crankshafts also possible, the grinding of their central bearings or main bearings with and without lateral radius transitions and possible plan sides, as well as the grinding of centric parts on the flange or pin, however, at these central parts of the flange and the pin no plan surfaces are mitgeschliffen.

Depending on the size and design of a crankshaft to be ground already when grinding with corundum grinding wheels due to the grinding wheels generated grinding pressure on the crankshaft to support the same when grinding lunettes used.

This problem of increased grinding pressure with concomitantly increased Zerspankräften occurs in the so-called. CBN grinding wheels in appearance since With them increased metal removal services must be driven, in general to make the grinding process economical. This is not only in the required cycle time, which should be achieved desirably, but also in the properties of the CBN grinding wheel itself. CBN grinding wheels, preferably those which are ceramically bonded and have a lining height of about 5 mm, on the one hand have the advantage that with them On the other hand, however, an increased cutting volume can be driven associated with the disadvantage that the cutting forces due to the specification The grinding wheels are higher, resulting in the entire grinding process technically made considerably more difficult.

However, there is a serious advantage of grinding with CBN grinding wheels in that increased cutting volume can be driven and that the dressing cycles increase by about ten times, which means that the main and Nebenzeiten itself in total on the production of a crankshaft related lower are. This is an increased output of crankshafts in relation possible on the time unit.

Although the use of such CBN grinding wheels is desirable by the increased grinding pressure, however, when sanding is just the grinding the crankshaft in the region of a main bearing at least until the hiring of the Abstützlünette as grinding technically particularly problematic.

Based on these considerations, it is the object of the present invention to develop a method and a device with which a considerable Improvement in terms of grinding the Lünettensitzes goes.

This object is achieved with a device according to the features of the claim 1 and a method according to the features of claim 8.

Basically, it is of considerable importance when grinding the Lünettensitzes firstly, that this has a very good concentricity with respect to the grinding Main bearing and secondly has a very good roundness in this regard.

According to the invention, the device is characterized by the fact that an additional processing unit for preparing at least one centric Bearing point of the crankshaft is provided for the final operation of the multi-bearing grinding is provided as a bearing seat for hiring a steady rest.

The processing unit is preferably an additional one Grinding unit with at least one grinding wheel for grinding the intended for the Lünettenlagersitz centric bearing of the crankshaft.

It is advantageous if the at least one grinding wheel of the processing unit has a narrower width than the width of the central bearing point, so a wide ground track for the bezel on the main bearing is generated, that the lunette jaws can be easily recognized. Here, the ground track must pass through the narrow grinding wheel is generated, be at least about 2 mm wider than the Lünettenbacken itself. These The procedure is mainly used where main bearings with corner radii must be ground.

According to the invention, the additional processing unit is the crankshaft either fed or swiveled to this when the grinding spindle for final multi-stage grinding of the crankshaft in disengaged position located with the crankshaft.

According to the invention, the multi-bearing grinding is performed so that before the Grinding the centric bearing points to final dimensions at least pre-ground the bearing point which is to serve as a bearing seat for a bezel. That is, all Processing steps are carried out at a clamping of the workpiece.

For this purpose, according to the invention, two fundamentally different possibilities. When grinding main bearings with lateral undercuts, in which the plan side of the main bearing is not mitgeschliffen is this procedure without the use of a so-called. Additional grinding possible, as previously in Connection with the device according to the invention described. Here it is required that on a main bearing of the crankshaft during pre-machining by means of whirl milling or turning an elevated contour stops, so that then during subsequent multi-bearing grinding in a grinding machine for multi-bearing grinding this increase is first ground off. The increase must be there represent at least the width of the produced Lünettensitzes, these Increase must already be cleanly ground before an adjacent one Main bearing is processed with the grinding wheel set. In other words, it can also here in terms of the required accuracy in terms of concentricity and roundness of the steady seat optimal values can be achieved. Subsequently the bezel is attached to this ground track and afterwards The grinding wheel set of the grinding spindle in the feed direction will continue to do so supplied and the one or more main bearings to the final finished size finished.

Another possibility is as previously related to described the device to grind the Lünettensitz by means of a grinding wheel, with an additional grinder inside the grinder is used.

In both cases, according to the invention, the steady rest for a perfect counter bearing during the multi-bearing grinding on the final dimension of the bearing always tracked, with gauges automatically turning the crankshaft during the process measure, making the grinding process virtually identical to grinding Corundum grinding wheels can be driven.

Figur 1

eine schematische Draufsicht auf eine Schleifzelle der erfindungsgemäßen Vorrichtung beim Schleifen des Lünettensitzes;

Figur 2

eine vereinfachte schematische Seitenansicht zur Darstellung der Anordnung der einzelnen Schleifscheiben;

Figur 3

eine schematische Draufsicht beim Mehrlagerschleifen der Kurbelwelle;

Figur 4

eine vereinfachte schematische Seitenansicht mit ausgeschwenkter Zusatzschleifeinrichtung;

Figur 5

einen Eingriff der Schleifscheibe beim Schleifen von Lagerstellen mit seitlichen Radien; und

Figur 6

ein Schleifen eines Lünettensitzes an einer Lagerstelle mit vorbearbeiteter erhöhter Laufspur.

In the following, the method and the device according to the invention in the course of the description of the embodiments illustrated with reference to the accompanying drawings. Show it

FIG. 1

a schematic plan view of a grinding cell of the device according to the invention when grinding the Lünettensitzes;

FIG. 2

a simplified schematic side view illustrating the arrangement of the individual grinding wheels;

FIG. 3

a schematic plan view of the multi-bearing grinding of the crankshaft;

FIG. 4

a simplified schematic side view with swiveled additional grinding device;

FIG. 5

an intervention of the grinding wheel when grinding bearings with lateral radii; and

FIG. 6

a grinding of a steady seat at a bearing with pre-machined elevated track.

FIG. 1 shows a simplified representation in the form of a plan view, wherein a crankshaft 1 with the clamping situation and the grinding wheel set 12, 13 is shown. The crankshaft 1 is in a floating chuck 6 is recorded with a tip 8 in the center of the crankshaft 1 and is positioned by a longitudinal stop 7 in its length.

The floating jaws of the chuck 6 span the Crankshaft 1 at its flange, so that the Radialmitnahme ensures grinding is.

On the side of the tailstock, the crankshaft 1 is also through a centering tip 9, so that the crankshaft 1 at both ends in their already machined centerings is added and tensioned, causing them in their position and tension is precisely positioned for grinding.

Furthermore, the measuring devices 4 and 5 constructed on the grinding table are shown, However, when grinding the bezel seat not on the crankshaft attack.

The bezel 3 is also built on the grinding table, but is located when grinding the bezel seat inevitably not with their jaws on the workpiece created.

The crankshaft 1 has a plurality of main bearings 15, namely in the present Example I, II, III and IV. The grinding of the Lünettensitzes takes place in the in Figure 1 shown representation on the centrally rotating main bearing II.

Here comes a processing unit 11 in the form of an additional grinding device For use, preferably with a spindle unit in the form of a Motor spindle is formed. This motor spindle increases in the front area her spindle nose a grinding wheel 10 on.

Thus, these additional grinding device 11 are pivoted to the crankshaft can, it must be parallel to the Z-axis, which is the CNC-axis represents the grinding table, and the grinding wheels 13 must by means of the X-axis, which serves for the feed movement of the grinding headstock 12, cleared become.

So that the crankshaft 1 does not have to be moved in the direction of the X-axis, When grinding the steady seat this additional grinding device 11 in the Art pivoted that the narrow grinding wheel 10 for grinding the Lünettensitzes essentially centrally in front of a grinding wheel 13 of the grinding wheel set the grinding spindle 12 is arranged. The X-axis, used for the procedure of Grinding headstock is used, on which also the additional grinding device 11 is constructed is used is that the grinding wheel 10 delivered to the crankshaft can be.

FIG. 1 further shows the grinding spindle 12, which is exactly parallel to the crankshaft extending central axis 14 around which the grinding wheels 13, for processing the main bearing I to IV, are rotatable.

The main bearings to be ground on the crankshaft 1 are denoted by the reference numeral 15 marked.

In order to minimize the cutting pressure when grinding the steady seat, the grinding wheel 10 has a width of about 10 to 12 mm, wherein the Lunette jaws, for example, about 8 mm wide As an abrasive for grinding the Lünettensitzes example, a grinding wheel made of corundum or a CBN grinding wheel are used.

In the present example, the auxiliary grinding device 11 is as einschwenkbare Unit described. However, it is also possible to use this additional grinding device 11 either at any position within the grinder or retract to swing.

FIG. 2 shows a greatly simplified side view in the region of the main bearing II of Figure 1 shown. The grinding wheel 10 for grinding the Lünettensitzes is arranged in front of a grinding wheel 13 of the grinding spindle 12. On average, the Crankshaft 1 shown. As can be seen, the center axes are all Grinding wheels 10 and 13 and the center axis of the crankshaft 1 aligned in parallel, these central axes preferably lie in a horizontal plane.

In Figure 3, the final operation of the multi-bearing grinding of the bearing I is now to IV shown, which are now polished time-parallel. This is mandatory since all grinding wheels 13 on the grinding spindle 12, which are mounted on both sides is, are included. The grinding wheel set is determined by the X-axis CNC-controlled. During the multi-bearing grinding is now at the main bearing II hired the bezel 3 with their jaws so that the workpiece during the grinding process is very well supported. To exact on the crankshaft 1 To achieve the diameter of the main bearings are preferably at the main bearings I and IV respectively a diameter measuring head 4 and 5 employed. During the Grinding, the crankshaft 1 is continuously in relation to the target and actual dimensions compared. The corrections then take place via the CNC control of the Machine, the measuring devices continuously the actual values at the diameter of the Main camp I and IV record. Once at one of the main bearings of the crankshaft 1 has reached the desired level during grinding, the grinding cycle is then ended and the grinding spindle 12 cleared.

Although the grinding of the main bearings on the crankshaft 1 is shown in FIG. However, it is also possible that more centric parts of the crankshaft 1 in the same setting with a modified accordingly Grinding wheel set can be ground.

FIG. 4 shows a simplified side view of that shown in FIG Top view in the area of the working space of the main warehouse II on it can be seen that then the additional grinding device 11 with the grinding wheel 10 upwards is swung out, but it is also conceivable that they are after construction of the Grinder and the available space in any other arbitrary Position can be pivoted in or out or moved.

Figure 5 shows in detail the process of grinding with the grinding wheel 13 am Main bearing of the crankshaft 1, wherein the main body of the grinding wheel 13A and the CBN pad is designated 14. The lining height is generally about 5 mm. On the main bearing of the crankshaft 1 shown here are also the lateral radii 15, as can be seen mitgeschliffen. At the radius transition in relation on the flat surfaces, for example, a Planschulterhöhe of about 4 grinded to 5 mm.

In the figure 6 is shown as a simplified representation, as with the grinding wheel 13 is ground at the main bearing. The main bearing has an elevation 16 on, by pre-processing, such as whirling or turning on one separate device was applied. It is clear that the Grinding wheel 13 only at the elevation 16 at this main bearing in schleifendem Engage, however, the side zones 17 and the other main bearings the crankshaft 1 when grinding the Lünettensitzes not be mitgeschliffen. After the lunette seat is sanded on the circumference of the elevation 16, is employed the bezel.

Subsequently, the grinding wheel set is delivered further, so that the crankshaft 1 can be ground to the finished final size.

LIST OF REFERENCE NUMBERS

1

crankshaft

2

Main camp I, II, III, IV

3

bezel

4, 5

Measuring device

6

chuck

7

longitudinal stop

8, 9

centering

10

grinding wheel

11

Machining unit, additional grinding device

12

grinding spindle

13

grinding wheels

14

central axis

15

Lateral radii

16

increase

17

Lateral zones

Claims (10)

1. Apparatus for the grinding of center bearings of crankshafts, having a clamping unit for clamping and for driving said crankshaft in its axis of rotation, a grinding spindle unit with a grinding spindle, the axis of rotation of which runs parallel to the axis of rotation of said crankshaft and which can be moved into place perpendicular to said crankshaft, wherein said grinding spindle carries a number of grinding wheels that corresponds to the number of center bearings to be ground, and at least one steady rest opposing said grinding spindle is used for bearing said crankshaft in the region of at least one center bearing, characterized in that one additional machining unit (11) is provided for preliminary work on at least one center bearing (2) of said crankshaft (1) for forming a bearing seat for the steady rests (3) which is elevated relative to the bearing, and wherein said steady rest (3) is embodied such that it can always be guided during the grinding of the bearings for counter bearing until the finished dimensions are attained.
2. Apparatus in accordance with claim 1, wherein said machining unit (11) is a grinding unit with at least one grinding wheel (10).
3. Apparatus in accordance with claim 2, wherein said grinding wheel (10) has a width that is less than the width of the center bearing (2).
4. Apparatus in accordance with claim 2, wherein said machining unit (11) can be driven into or pivoted into contact with said crankshaft (1) between said crankshaft (1) and said grinding spindle (12) when the grinding spindle (12) is in a non-contact position.
5. Apparatus in accordance with claim 4, wherein the drive of said machining unit (11) is embodied separately.
6. Apparatus in accordance with any of claims 1 through 5, wherein the steady rest (3) can be automatically positioned at the corresponding center bearing of said crankshaft (1).
7. Apparatus in accordance with any of claims 1 through 6, wherein said grinding wheels (10, 13) are CBN grinding wheels.
8. Method for the grinding of center bearings of crankshafts, wherein said center bearings are ground simultaneously by using a wheel set for the grinding of multiple bearings, characterized in that prior to the final grinding of said center bearings (2) to their final dimensions, on at least one bearing, a bearing seat for a steady rest (3) with a higher dimension relative to the bearing is ground, and during grinding of said bearing seat to the final dimensions, said steady rest (3) is guided to the final dimensions of said bearing seat.
9. Method in accordance with claim 8, wherein said bearing seat is initially ground with a first grinding wheel (10) and then the grinding of the center bearings (2) of said crankshaft (1) is finished with said grinding wheel set after said steady rest (3) has been positioned.
10. Method in accordance with claim 8, wherein said bearing seat is initially ground with a grinding wheel (13) of said grinding wheel set to an elevated contour (16) of said main bearing and then the grinding of the center bearings of said crankshaft (1) is finished with said grinding wheel set after said steady rest (3) has been positioned.

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