DE102004013192B3 - Bearing and cams grinding method e.g. for cam shaft, involves having cam shaft consisting of steel tube and cam directs tube toward grinding machine, with which after sharpening procedure directs cam shaft toward same grinding machine - Google Patents

Abstract

It be a method for grinding bearings and cams one built camshaft and for straightening the same on a grinding machine and a device described in particular for carrying out the method, by means of which after a grinding process on the same Schleifmaschne a straightening process is carried out by means of a straightening device. In particular, after the bearings have been finished are for what steadies used as supports be, first these supports out of engagement brought with the respective bearing point of the camshaft, to which preferably measuring a concentricity value of the bearing in the middle area connects. To Determination of the concentricity of the bearings in the middle area subsequently preferably on the basis of the measured concentricity value of the straightening process on the grinder. For this purpose, the device has a straightening device which is integrated in the grinding machine.

Description

The The invention relates to a method and a device for grinding of bearings and cams of a built camshaft.

built Camshafts go through in the operations preceding the grinding Joining of Components assembled to a complete camshaft. there is the actual body the camshaft made of a steel tube, which is usually drawn bare is and in addition indentations may have in areas between the individual cams. The cams are manufactured separately and, for example, in a shrinking process Shrunk on the corresponding points of the steel tube, wherein subsequently Before grinding can still take place turning and milling operations. The Shrunk cams are usually previously cured. such Built camshafts have the advantage that they are compared to the conventional casting camshafts a significant reduction in mass enable. In order to optimize the mass reduction, the wall thickness of the Steel tube as possible to keep low. The smaller the wall thickness of the steel tube of the camshaft is, the stronger it gets such a built camshaft then as a separate component relative unstable. Although this instability is in the installed state of Camshaft in the engine again somewhat eliminated by the camshaft is received and held in the bearing shells of the engine.

One Another advantage of built camshafts is that different Materials for cams and bearings can be used to differentiate To be able to take better account of loads on the component.

The built-in camshafts also exhibit the advantage that their production also partly considerably cheaper is. For these reasons Built-up camshafts are becoming increasingly popular in engine construction, being recognized that, despite the relative stabilization in the built Condition through the bearing shells of the engine block the requirements to the accuracy, in particular the concentricity of the camshafts, getting higher and higher.

On Reason of the described fact that the built camshafts in terms of their deflection with respect to their longitudinal axis are relatively soft, are for the machining of such built camshafts on grinding machines special requirements for their grinding process and their clamping to put while grinding. When grinding the bearings of the built Camshafts are two basic process variants known. To the one is the grinding of bearings in the so-called centerless grinding process, and on the other hand, the grinding of the bearings takes place in such a way that the camshaft is clamped between points and the bearings be ground sequentially, partially parallel or parallel. Since in this latter known grinding method when grinding the Bearings lunettes are used, already a relatively good concentricity, in particular the inner bearing points, i. the middle of the camshaft arranged bearings, with respect arranged at the shaft ends (outer bearings) Storage locations reached. Today, concentricity demands of for example 4/100 mm and less required, which complied with process reliability Need to become.

The Processing, i. the grinding of such built camshafts takes place in one or more fixtures. If it succeeds, to realize the clamping of the camshaft in the same places, play it for the final quality the generated camshafts do not matter, whether in two or more clamping work or even worked in one clamping becomes. The problem with the built camshafts is under also in the fact that the workpieces themselves when grinding the Bearings and the cam shape by the introduction of energy, by the grinding process as such and by the grinding the hardened surfaces warp the cam. This process is known per se. In such workpieces, which joined in the cold state have been and which on their surfaces such as just the cam surfaces are hardened, are due to these influences mentioned in the material contained Tension when grinding at least partially free. These tensions then lead to make the shaft distort. That means the camshaft After grinding is no longer straight, so a so-called blow occurs, which is particularly increased at the inner bearings, if only by a few hundredths of a millimeter. This increase in Blow leads ultimately, that the camshaft is no longer reliable in the required tolerance is.

So far one has proceeded in the operational practice so that the concentricity properties the built camshafts were measured before grinding. When passing The tolerance values were the built camshafts even before grinding directed. It was then expected that there would be an additional loop generated Impact was within the required tolerance for the finished camshaft. If the tolerance was still exceeded, had taken the relevant built camshaft from the manufacturing process become.

The Requirements for the concentricity of the assembled crankshafts but are always higher with time become. First, the steel pipes, which was the main body of the built crankshafts, always thin-walled, because the rotating Were to reduce masses. On the other hand, the tolerance limits for the Concentricity increasingly restricted. Therefore, it can no longer be used according to the usual practice in business practice Be proceeded way.

The DE 196 26 189 A1 deals with a method for grinding rotating workpieces, also mentioning the non-circular grinding of workpieces such as camshafts. This known grinding method assumes that the delivery of at least some delivery steps is controlled as a function of the respective remaining material allowance. For this purpose, the associated grinding machine is equipped with a measuring device that constantly provides information about the actual value of the material allowance during the grinding process. In a particular embodiment of the known method, it is provided that the rotating grinding wheel is adjusted to the workpiece at each workpiece revolution by a delivery amount which depends on the grinding-optimum clamping thickness and a correction quantity. The correction quantity detects the amount of elastic deflection that results at the workpiece transversely to its longitudinal axis, because the grinding wheel is pressed against the workpiece during grinding.

The current material allowance is in the known method according to the DE 196 26 189 A1 always detected at the end of a workpiece revolution, when the delivery of the grinding wheel has already taken place; Therefore, the measured value of material allowance can only be used to control the infeed during the following workpiece revolution. Since the workpiece deflection in the course of the following workpiece revolution with reduced material allowance but with the workpiece deflection during the previous workpiece rotation usually does not match, the expected for the following workpiece revolution workpiece deflection must be calculated in advance to to come to a useful value for the said correction quantity. Here, the rotational speed of the workpiece is taken into account.

In the DE 196 26 189 A1 is not addressed to the particular problems of built camshafts with thin-walled steel tubes as a basic body. In addition, due to the delivery of the grinding wheel coming elastic deflection of the camshafts is something other than the consideration of concentricity errors in the grinding process, because these concentricity errors are based on a stroke of the camshaft, ie a plastic deformation. From a blow and the straightening of the workpieces to eliminate the blow is in the DE 196 26 189 A1 nothing mentioned.

It is therefore the object of the invention, a method and an apparatus for grinding built-up camshafts with respect to the previously achievable accuracies improved concentricity properties to accomplish.

These The object is achieved by a method having the features of patent claims 1, 5 and 6 and by a device having the features of claim 19 solved.

By the inventive method and the device according to the invention is advantageously achieved that the delay in the finished Camshaft greatly reduced or even eliminated altogether. at the method according to the invention takes place according to a first aspect of grinding bearings and cams of built Camshafts and straightening these camshafts on a grinding machine, and that is after a grinding process on this grinder also done the judging. Preferably, the grinding process is either finish grinding the bearings and / or a pre-grinding of the cams and / or a Finish grinding of the cams. Preferably, according to a Development of the invention, the implementation of the method steps Finish grinding of bearings, rough grinding and finish grinding the cam and straightening in a single clamping.

According to one Another aspect of the invention, first, the bearings of a built camshaft on a first station of the grinder Finished and then the cams of the camshaft pre-ground on a second station of the grinding machine and Finished on this grinder also, after which Pre-grinding and / or finish grinding the camshaft on this second grinding machine is directed.

According to yet another aspect of the invention, the bearings of a built camshaft are finish ground on a first grinding machine and directed on the same grinding machine, followed by pre-grinding and finish grinding of the cams of the camshaft on a second grinding machine. It is of course possible that even on the second grinding a further straightening process can take place. This straightening process can be done after pre-grinding and / or after finishing grinding of the cams. Preferably, however, ge in the method according to the invention, only a single straightening performed.

Preferably is used for grinding bearings and cams of assembled camshafts on a grinder while grinding the bearings, the camshaft at bearings especially with lunettes supported being first the bearing points are finished and then the grinding process used supports, i. lunettes, solved become. That concludes measuring in a preferably second process step the bearings especially in the central area of the camshaft on concentricity accuracy. The measured concentricity value or the Deviation from ideal circulation is preferably stored and serves in a subsequent Procedural step to the camshaft based on the the same grinding machine. With this straightening becomes the concentricity not only improved, but the deviation from the ideal concentricity can even almost eliminated. This additional step of judging may after finishing grinding of the bearings and / or preferably after the pre-grinding of the cams and / or after finish grinding the Cams take place. The bearings can be used to, the for the straightening process required forces to initiate there. These straightening forces can also be initiated in addition to the depositories, in any case in the steel pipe.

at a component such as a camshaft with divided in the axial direction Sections, the maximum deviation from concentricity is known to occur mostly in the middle area. Therefore, the depository will become the Measure bearing points in central area of camshaft for concentricity. Subsequently In the area of these bearings, the straightening forces become Achieve as much as possible ideal concentricity initiated. Under concentricity should in the following in particular the concentricity of the inner bearing points to the outer bearing points and the bearing point to the base circle of the adjacent cam or Cam pair understood.

According to the invention is of Meaning that between different grinding operations a straightening process added becomes. However, it is also possible such a straightening process after completion of the last grinding process perform. In any case, it is necessary when grinding the bearings and / or the cam as a result of the released voltages themselves compensate for deteriorated runout characteristics a higher one Accuracy, i. a higher one precision the concentricity of the camshaft in the middle of Bearings regarding to reach the final bearings of the camshaft. These are the Finished bearings. In a further step, the Cam shape are pre-ground, followed by a straightening followed, in turn followed by a finish grinding operation for the cams. That's what it can do in turn connect a straightening process. Preferably, however, will only worked with a single straightening process.

If the straightening process after pre-grinding the cam of the camshaft takes place, are preferably the supports in the form of particular steadies again hired to the respective bearing points, whereupon the Finish grinding of the cam connects.

Preferably, the straightening is performed with a rotating camshaft, wherein the camshaft rotates at a speed of in particular 50-200 min ^-1 . The actual straightening is preferably achieved at the specified speed by introducing a compressive force at the central bearing point of the camshaft. In this Rollrichtverfahren a measurement of the camshaft with respect to concentricity accuracy is not mandatory because the camshaft is strained during straightening on the yield strength of their material.

Around To be able to effectively effect the straightening process is preferably done the straightening in the camshaft preferably at least partially over the Plug limit of the material of their steel pipe addition. Under "regionally" should in the following in particular, be understood that when about a Walk corresponding scrolling at least areas of the steel pipe in the structure essentially made tension-free by permanent deformations become. That the material of the camshaft is suppressed, followed by a gradual withdraw the deflection of the camshaft to substantially 0 mm connects. The practiced Pressure is thus gradually withdrawn so that the deflection goes back again.

According to a further preferred embodiment, however, it is also possible that the straightening takes place when the camshaft is stationary. Initially, the deviation from the ideal concentricity is determined at a bearing point, while the bearing point is measured, which has the highest deviation from the ideal concentricity. This will usually be a bearing point in the central region of the camshaft. During measurement, the largest impact, ie the radial position, is determined in which the highest runout occurs in terms of absolute value. At this radial point, the compressive force is then initiated, whereby by means of this pressure force a deliberate bending of the camshaft is generated. The initiation of the compressive force or reducing the amount of this compressive force is adjusted to the actually measured value of the runout on the respective La ger.

If at according to the first Aspect of the invention all Process steps are realized in a single clamping, has a device for carrying out the method in such Case a grinding machine with a corresponding number of grinding spindles and a straightening device. This has the advantage of transformer operations omitted and the otherwise additional Effort and additional Cost-requiring care, with renewed restraint at least almost identical clamping conditions to achieve, deleted there. Surprisingly has now been shown that with the inventive method even then desired Results regarding a high accuracy of the concentricity properties By built-in camshafts can be achieved when on a grinder with several workstations after finishing the bearings or pre-grinding the cams the camshaft re-clamped and the process of straightening is then in the second set, however, carried out on the same grinding machine. Unless when re-tightening at least almost identical clamping conditions can be achieved a re-clamping also take place between any method steps.

Preferably Furthermore, it is a concentricity measuring device in the grinding machine the device according to the invention integrated. This concentricity measuring device becomes a concentricity value or runout value determined. The concentricity measuring device is preferably over a control device connected to the straightening device, so that the straightening device based on the measured concentricity deviation value for the Straightening process is optimally controlled, in such a way that the runout after straightening is at least largely eliminated.

According to the first Aspect of the invention, the method takes place on a single grinding machine. However, this grinder may have two stations. On The first station of this grinding machine is finished grinding the depositories. On the second station, on the other hand, the Pre-grinding and finish grinding of the cams of the camshaft. It but it is also possible that the pre-grinding of the cams also already on the first station the grinding machine performed what is the finish grinding of the cams on the second Station of this grinder connects. The process step of Aligning the camshaft can after pre-grinding of the cam done on the first station. However, it is also possible the Step of straightening following finish grinding to perform the cam on the second station. Regardless of whether judging the camshaft takes place in the same clamping or whether the Straighten in the first station or in the second station of the grinder carried out is, the straightening process takes about 5 to 15 seconds. That means, that the straightening process itself is much faster than a second sanding cycle. To the other leads judging that the unit cost be significantly reduced. In view of the fact that camshafts always in relatively high volumes needed be, the unit costs play a crucial role for the Cost-effectiveness of the process. Surprisingly, it has become now shown that in the relatively short time of 5 to 15 seconds very good results in terms of improving the concentricity properties compared to those with conventional technologies achievable concentricity can be achieved.

According to the second and the third aspect of the invention, the finish grinding takes place on a first grinding machine and pre-grinding and finish grinding the cam on a second grinding machine. In any case, will the method on at least one grinding machine at least partially so realized that a grinding process and a straightening process on this Grinding machine performed become. On the one hand this can be a directing of the camshaft after the Finishing the bearings on the first grinding machine be. However, this can also be a straightening after pre-grinding and / or finish grinding the cams on the second grinding machine. However, it is also possible that on both the first grinding machine after finish grinding the bearings are straightened and after pre-grinding and / or finishing grinding on the second grinding machine.

According to a further aspect of the invention, the device according to the invention for grinding bearings and cams of a built camshaft and for directing such a built camshaft, in particular for carrying out the method according to the respective method claims, a grinding machine, which with a straightening device for Alignment of the camshaft is provided after a corresponding grinding operation and preferably also with a concentricity measuring device for measuring the concentricity or the runout of the camshaft. The concentricity measuring device - if this is available - and the straightening device are integrated into the grinding machine according to the invention. In the apparatus according to the invention is a grinding machine whose actual grinding task is extended by a straightening process, wherein preferably additionally the concentricity measuring device is integrated in this grinding machine. It is used to control the straightening device, ie to carry out the straightening on the basis of measured concentricity value or the measured concentricity deviation. With such a device, it is thus possible to produce built camshafts, the basic carrier is a hollow shaft on which the cams are pressed in particular in the joining process, with higher precision of their concentricity properties than is the case with the known grinding machines, which are not for the Step of judging are provided. Only with the device according to the invention can the straightening be carried out within the same modified grinding machine after a grinding operation. Under run-out characteristics or deviations of the concentricity properties should be understood how much the bearing point or bearings in the central region of the camshaft with respect to their concentricity with respect to the longitudinal axis of the camshaft deviates from the concentricity of the bearing points at the ends of the camshaft or deviate. Of course, these end bearings are much less subject to runout than the central and central camshafts because the end bearings are respectively clamped on tips in the grinding machine.

Of the essential part of the device according to the invention, namely the Grinding machine has in a conventional manner on one a machine spindle worn wheel spindle, which two in a respective grinding position einschwenkbare grinding wheels may have, as well as recorded on a grinding table Workhead and tailstock up. The built camshaft is between the tips of workpiece headstock and Tailstock clamped. Preferably, the Rundlaufinesseinrichtung on the wheelhead or on the grinding table and is the Straightening device attached to the wheelhead. By the Fixing the concentricity measuring device on the wheelhead or on the grinding table a high measuring accuracy is ensured because the reading is always on the through the respective grinding wheel scoring result is coupled. This also applies to the straightening device to which ensures by their arrangement on the wheelhead, that in conjunction with the high-precision measured value for the concentricity deviations a corresponding introduction of the straightening force in the camshaft guaranteed can be and thus with the device according to the invention a high precision of Straightening process can be achieved.

According to one preferred embodiment of the invention, the grinding machine the device according to the invention a first station for grinding the bearings and / or rough grinding the cam of the camshaft, in which also a straightening device can be provided for straightening the camshaft. Furthermore is the second station for finishing the cams of the camshaft also provided with a straightening device. The grinding machine the device according to the invention can therefore have a first station, in which a straightening device may be provided, but not must. Preferably is also in the second station provided a straightening device, so that after the finish grinding of the cam straightening or possibly the Endrichtung of the camshaft can be performed. in principle it goes without saying possible, split the straightening process into two parts, so that after pre-grinding the cam the straightener is used and that too after finishing the cams on the second station provided straightening device can be applied. Preferably has for this purpose both the first station and the second Station on a straightening device. This is a full flexibility of the grinding machine the device according to the invention given. However, it is also possible that the first station is designed so that the grinding of Bearings and the pre-grinding of the cams of the camshaft on it can be realized, the straightening device then either after the grinding of the bearings or after the subsequent roughing process the cam of the camshaft is used. In the second station the grinding machine of the device according to the invention then takes place only the finish grinding of the cam of the camshaft, what preferably also another straightening process, a so-called Final alignment process, connect can. Preferably, however, as always, the division is attempted the grinding operations and judging between the first and second stations, with a single straightening the required concentricity to achieve the built camshaft. It is also possible that the straightening device of the first station after pre-grinding not used and only the straightening device of the second station a single straightening process after finishing the cams realized.

Preferably, the straightening device is a roll straightening head, which is designed so that the straightening is executable with a rotating camshaft. The rotational speed in the roll straightening process performed by means of the roll straightening head is preferably in the range of a rotational speed of 50 to 200 revolutions per minute. Preferably, the roll straightening head has two rollers mounted in its front area. The term "front area of the roll straightening head" is to be understood as meaning the area which points directly onto the area of the corresponding bearing point of the camshaft to be straightened.The roll straightening head is preferably fastened on the wheelhead and preferably in the X direction on the bearings of the The delivery of the roll straightening head to the bearings depends on this the measured by the measuring device concentricity deviations at the respective bearing point and thus determines the force to be exerted on the camshaft at this bearing point to complete the straightening process so that after the straightening the camshaft as ideal as possible concentricity, ie has ideal concentricity.

It understands that for the control technology connection of the measuring device and the straightening head mutually corresponding calculation and control devices are provided including the corresponding actuators to implement the measured value the one you want Deflection corresponding introduced force value. When roll-straightening Preferably, measuring is not required. The straightening head is It is designed so that this after the initiation of Straightening these gradually withdraws again, i.e. reduced. The force, which with the roll straightening head on the corresponding bearing point of the camshaft is exercised, is so high adjustable, that exceeded the elastic deformation range becomes, so that by a plastic deformation actually one Straightening effect occurs. By a gradual, thus gentle modulation, i.e. withdraw the imprinted Straightening force can continue with the rotating camshaft during the Aligning the straightening process gradually to be ended. This makes it possible the strongest a deformation underlying central portion of the camshaft desired To give a straightening effect.

According to one another preferred embodiment if the straightening device is designed as a pressure element straightening head, which executes the straightening when the camshaft is stationary. at the straightening carried out with the camshaft stopped works in terms of control technology the measuring device with the straightening head via corresponding electronic devices together. First is determined with the measuring device, the value at which the corresponding bearings, in the radial direction of the respective bearing seen, the biggest rash, hence the biggest run-out error having. And exactly at this point or in this area of the biggest blow at the bearing point of the camshaft is the force by means of the pressure element straightening head initiated. This force will depend on the measured Beat adjusted so that the deformation in the plastic area goes, so that a permanent straightening effect is present. The straightening head can be designed so that in a single straightening process this straightening effect is achieved. However, it is also possible the To carry out leveling process in several steps, with different Forces then at different radial positions to eliminate the in initiated the respective area of the deposit existing blow can be.

Preferably the pressure element straightening head is designed as a mounted prism with a recess, by means of which a certain area of the circumference of a corresponding Bearings of the camshaft can be encompassed, being over this peripheral area the introduction of a respective desired straightening force over at least two circumferentially spaced Make a bearing point of the camshaft. However, it is also possible, to design the prism in such a way that the two side flanks and the base of the prism during the straightening process at the respective location abut the circumference of the bearing, so that the straightening force over three points is initiated. Such a tuning of the shape of the prism with the diameter of the bearing to be ground has the advantage that in particular with a blow of a larger kind an effective straightening allows becomes.

Besides that is it is preferably possible that the pressure element straightening head is a pressure element which has an in Essentially flat surface has to introduce the straightening force. With the pressure element is the corresponding straightening force a point at a bearing point of the camshaft can be introduced. Instead of the flat surface or of the prism, of course, other forms are conceivable such as a curved one Shape whose radius is larger as the radius of the corresponding bearing point.

Further Advantages and applications The invention will now be described with reference to the description on the attached drawing explained in detail. In the drawing show:

1 a built-up between spikes built camshaft whose bearings are being ground straight;

2 a built-up between spikes built camshaft whose cams are being ground;

3 a device according to the invention with two stations each for grinding and straightening the camshaft;

4a) to d) the essential process steps of the process according to the invention;

5 a roll straightening head of the device according to the invention at a bearing point of the camshaft;

6 a pressure element straightening head with pendulum-mounted prism when straightening at a bearing point of the camshaft;

7 a pressure element straightening head with plane surface when directing a bearing point of the camshaft; and

8th a further embodiment of the method or the device according to the invention in a schematic representation.

In 1 is a schematic representation of the construction of a built camshaft 1 with corresponding bearings 2 and shrunk cams 3 shown which between peaks 14 is held. The tips are on the workpiece headstock 12 and on the tailstock 13 arranged. The tips 14 are designed so that they engage in the center of the steel tube of the camshaft and achieve a corresponding clamping effect at these ends, so that on the one hand torque can be transmitted to the camshaft and on the other hand, the voltage is not so high that already by the clamping the camshaft undergoes deformations. Shown are two grinding wheels 23 . 24 , which are on a common wheelhead 7 are arranged and in the grinding position for grinding the respective bearings 2 the camshaft 1 to be brought. The grinding wheel 23 opposite is a bezel for support during the grinding process 11 arranged. Through the supporting effect of the bezel 11 ensures that when grinding in the bearing L2 of the camshaft 1 introduced grinding forces do not lead to a deformation of the camshaft. Another bezel 11 is attached to a place where grinding is not going on. Furthermore, the grinding wheel 24 engaged at a bearing L5. Not shown is a corresponding straightening device.

1 represents the first process step, according to which first the bearings 2 the camshaft 1 be finished. Only after all bearings 2 have been ground, a straightening process or a first straightening process can be performed.

In 2 is a state during the process shown in which the cams 3 through grinding wheels 9 . 10 be sanded. The grinding wheel 9 used for pre-grinding and the grinding wheel 10 for finish grinding of the cams. The bearings 2 are through lunettes 11 supported. The grinding wheels 9 . 10 are designed so that the pairs between them a respective bearing enclosing cams are ground simultaneously. In analogy to 1 is the camshaft 1 also between peaks 14 of the workpiece spindle 12 and the tailstock 13 added. For radial movement of the camshaft 1 is a chuck on the workpiece headstock 28 appropriate.

In 3 a device according to the invention is shown in which the grinding machine 4 from a first station 15 and a second station 16 consists. In the first station 15 is a camshaft 1 on tips 14 between a workpiece headstock 12 and a tailstock 13 clamped. steadies 11 are at warehouses 2 the camshaft 1 moved to support them. The lunettes 11 are approachable by an adjustment in the X direction to the respective bearing point for support. The lunettes 11 Opposite is a wheelhead 7 on a machine bed 8th arranged. The wheelhead 7 is pivotable in B direction and carries two spindles, of which a first spindle a first grinding wheel 23 and a second spindle a second grinding wheel 24 wearing. By pivoting the wheelhead 7 become the respective grinding wheels 23 . 24 pivoted into the grinding position for grinding the bearings. In the first station 15 the bearings are finish ground.

On the wheelhead 7 is a concentricity measuring device 5 arranged, which by pivoting the wheel spindle 7 can be brought into a measuring position in the central region of the camshaft. After the concentricity measuring device 5 it has been pivoted to its measuring position, it determines at a bearing to be measured 2 their concentricity properties or their deviation from an ideal concentricity. For clarity, is at the first station 15 the straightening device 6 only schematically drawn. The concentricity measuring device 5 controls the straightening device on the basis of the measured value of the concentricity of the measured bearing point in the central region of the camshaft 1 such that with her such a force, after the lunettes 11 have been moved out of their support position of the bearings, is introduced into the camshaft that the latter is directed and then has improved concentricity properties. The forces introduced are so high that by means of a permanent plastic deformation, the camshaft is brought closer to or even in their ideal condition with respect to the run-flat characteristics. The straightening is preferably done after completion of the finish grinding process of the bearings in the first station 15 , in the same setting and takes about 5 to 15 seconds. This is particularly advantageous, especially with high quantities in mass production, as is the case for camshafts.

In principle, however, can also be directed Process after the finish grinding of the bearings 3 in the first station 15 dispensed when straightening after pre-grinding or finish grinding the cam 3 in the second station 16 is carried out. The advantage of straightening at the end of the finish grinding operation for the cams is that it also eliminates straightening strains caused by the release of stresses when grinding the hardened surfaces of the cams, resulting in deformation of the entire camshaft as well 1 can contribute. The basic construction of the second station 16 corresponds to the first station 15 , where the first station 15 and the second station 16 to a single grinding machine 4 are joined together. This corresponds to a conventional modular design, whereby the advantage of the device according to the invention comes particularly to bear, because the straightening usually takes place in the same clamping as the respective grinding process. Also the second station 16 has a wheelhead 7 on which one on a machine bed 8th is stored. The wheelhead 7 has two spindles for one grinding wheel each 9 . 10 on. On the wheelhead 7 is in the range of the grinding spindle for the grinding wheel 10 a concentricity measuring device 5 provided, which is arranged so that when pivoting the grinding wheel 10 in the respective grinding position for finishing the cams the concentricity measuring device 5 can be brought to a bearing in the central region of the camshaft. The measurement of the bearing in the central region of the camshaft is above all useful and necessary, since there the distortion of the camshaft has the most effect. For reasons of clarity is also here in the second station 16 the straightening device 6 only schematically drawn. Of course, this concentricity measuring device is also 5 connected via a control device, not shown, with the straightening device in order to determine the distortion of the camshaft corresponding straightening force and to bring out after introduction of this straightening the straightening device with gradual reduction of the force introduced slowly back out of direct contact with the camshaft.

The camshaft 1 itself is between peaks 14 in a chuck 28 of the workpiece headstock 12 on one side and in a corresponding tip 14 of the tailstock 13 kept on the other side. The camshaft 1 itself is at their campsites 2 by a number of lunettes corresponding to the number of bearings 11 supported. Additionally in the second station 16 arranged is a dressing device 25 for dressing the grinding wheels 9 . 10 ,

In 4 is in principle the representation between peaks 14 held camshaft 1 for different process steps, which are carried out in the device according to the invention shown. The between peaks 14 held camshaft 1 is at her between the cams 3 located bearings 2 using lunettes 11 supported ( 4a ). The bearings 2 are already finished ground, so that at the finished ground bearings lunettes 11 supporting the camshaft 1 moved up. In this supported state, the cams 3 pre-sanded. By the support with the lunettes 11 is achieved that, despite the introduction of grinding forces on the cams 3 When grinding the cam, the deformation of the camshaft 1 is kept low due to the grinding operations.

After the cams 3 have been pre-ground, be in accordance with 4b) the lunettes 11 out of engagement with the camshaft 1 hazards. The between peaks 14 clamped camshaft 1 is in rotation and during its rotation by means of the concentricity measuring device 5 measured for their concentricity or concentricity deviations. This measurement takes place at the central bearing point of the camshaft, because there the expected runout is greatest.

After the concentricity measuring device 5 has determined the value for the concentricity deviation at the central bearing point, is a control device for the straightening device 6 a signal corresponding to the measured value is supplied. On the basis of this the concentricity deviation reflecting signal is the straightening device 6 in still not engaged lunettes 11 to the middle bearing point of the camshaft 1 hazards. The by means of the straightening device 6 in the camshaft 1 introduced force is chosen so that it is above the yield strength of the material of the camshaft to achieve a permanent deformation, thus achieving the desired straightening effect. The straightening compensates for the deformations occurring during grinding as a result of the introduction of grinding forces and as a result of internal stresses released by the grinding. The concentricity measuring device 5 is preferably not used when roll-straightening is used.

When the straightening process according to 4c) after finish grinding the cams 3 carried out, for example, in the second station 16 the grinding machine 4 (please refer 3 ) can be performed, then provides 4a) the state in which the finish grinding of the cam while supporting the corresponding bearings 2 through lunettes 11 is done or already finished. In this case, after completing the straightening process according to 4c) the camshaft 1 finished with maximum precision in terms of their concentricity properties and can be removed from the grinding machine 4 or the second station 16 the grinding machine machine 4 be removed.

If the according to 4a) to 4c) Procedures refer to the case in which the cams 3 it is of course necessary to carry out a further method step with the device according to the invention. This is in 4d) shown in which the lunettes 11 again to the appropriate storage locations 2 are introduced so that it is the finish grinding process for the cam 3 can connect. The actual grinding processes or the grinding wheels are for the sake of simplicity in 4 not shown, since the basic structure of the grinding machine 4 out 3 is apparent. At the finish grinding of the cams 3 according to 4d) Of course, also a straightening process according to 4c) connect.

5 shows an embodiment of a straightening device 6 for a case where the camshaft is pointing between the tips 14 of the workpiece spindle 12 and the tailstock 13 is recorded and is rotationally driven during straightening. For this purpose, the straightening device is a roll straightening head 17 formed, which at its front end two bearing rollers 18 having. This roll straightening head 17 with his roles stored 18 adapts to the contour of a camshaft 1 in the area of their bearings 2 at. The straightening device can be delivered to the camshaft in the X direction, so that with simultaneous rotation of the camshaft 1 and pressing the roll straightening head 17 with his roles 18 The camshaft can be deformed so that it is over the yield point of their material is suppressed. The straightening forces are thus on the also rotating during rotation of the camshaft roles 18 at the contact points of the rollers 18 at the respective bearing point in the camshaft 1 initiated. After the maximum straightening force has been initiated in the corresponding area of the bearing of the camshaft 1 , Then the deflection of the camshaft by gradual retraction of the roll straightening head 17 withdrawn to a deflection value of 0 mm. This roll straightening allows rotationally symmetric shafts to be directed relatively quickly and reliably. Above all, this procedure is also on the grinder 4 The device according to the invention can be used, since it is very fast. Such a roll straightening process takes about 5 to 15 seconds. This is considerably shorter than an otherwise to be performed second grinding pass, with which the concentricity with the precision, as they are achieved by the device according to the invention or the inventive method, yet can not be achieved.

In 6 is another embodiment of a straightening device 6 shown. It is a straightening device which is suitable for a pressure-straightening process. Such Druckrichtverfahren takes place when the camshaft is stationary 1 instead of. Here, first, the concentricity or the deviation from the concentricity at the central bearing point of the camshaft or at a bearing point in the central region of the camshaft is measured. This measurement measures the "highest point" of the bearing revolution to determine the radial position at which the maximum concentricity error occurs 1 is now bent with this pressure straightening against their maximum deflection so that this maximum deflection is eliminated as completely as possible. This straightening process can also be in the clamping of the camshaft between the tips 14 take place, after determining the maximum deflection, ie the maximum runout error, the camshaft is rotated radially so that a pressure element straightening head 19 in the X direction in this area of the circumference of the corresponding bearing point of the camshaft 1 is adjusted to the camshaft so that a corresponding straightening force can be applied to them. For this purpose, the printing element straightening head 19 on its front a stored prism 20 on which a recess 21 has, so that a peripheral region of the bearing 2 the camshaft 1 can be included or recorded. The straightening force is thus over two optionally also three contact areas in the recess 21 of the stored prism 20 initiated.

Another embodiment of a printing element straightening head 19 is in 7 shown. Here is the printing element straightening head 19 with a pressure element 22 provided, which has a flat or spherical (not shown) surface, via which the force in the region of the corresponding bearing point 2 is initiated. Analogous to the embodiment according to 6 The straightening force is also at the point in the corresponding bearing point of the camshaft 1 initiated, at which the largest deflection, ie the largest concentricity error occurs. In this straightening method according to the 6 and 7 Therefore, the camshaft is "bent" by a certain value against the highest circulation point in order to compensate for the existing concentricity error, whereby the camshaft stands still during the straightening.About its longitudinal axis, the camshaft is here merely rotated into the radial position required for straightening, but then stopped to perform the straightening process.

These straightening methods are also suitable for straightening a camshaft in such a way that the camshaft at the two outer bearings - instead of between tips 14 to be held - by lunettes 11 is supported. In such a case, the middle bezel 11 disengaged be, so the appropriate straightening device 6 in engagement with the center bearing of the camshaft can be brought to their straightening. This is in 8th represented in a principled way. Such a straightening method is especially advantageous when the camshafts have been ground "centerless" before the cam grinding.

In both straightening methods is the straightening device 6 on the wheelhead 7 arranged and is preferably delivered over the X-axis. The infeed values for both straightening methods are the camshaft geometry, the material and also the clamping of the grinding machine 4 or determined by the degree of hardness of the cam surfaces. The infeed values may be in the CNC control of the grinder 4 calculated, with respect to the previously measured concentricity error. After straightening, concentricity errors of less than 0.01 mm can be achieved at the middle bearing point. For grinding CBN grinding wheels are preferably used.

1

camshaft

2

depository (L1 to L5)

3

cam

4

grinding machine

5

Concentricity measuring device

6

leveler

7

Wheelhead

8th

machine bed

9 10

grinding wheels

11

steadies

12

Workhead

13

tailstock

14

sharpen

15

first Station of the grinding machine

16

second Station of the grinding machine

17

Roll straightening head

18

roll

19

Pressure element straightening head

20

prism

21

recess

22

pressure element

23 24

grinding wheels

25

dressing devices

28

chuck

Claims (31)

Method for grinding bearings and cams a built camshaft, with the camshaft made of a steel tube and the cam, and for straightening the same on a grinding machine, in which after a grinding process straightening the camshaft done on the same grinder. The method of claim 1, wherein the straightening the camshaft after a finish grinding of bearings and / or a pre-grinding of the cams and / or a finish grinding the Cams performed becomes. The method of claim 1 or 2, wherein the Process steps finish grinding of bearings, rough grinding and finish grinding of the cams and straightening in one clamping respectively. Method according to claim 1 or 2, wherein the Finish grinding the bearing points of the camshaft on a first Station of the grinding machine and pre-grinding and finish grinding the cam of the camshaft take place on a second station. Method for grinding bearings and cams a built camshaft, with the camshaft made of a steel tube and the cam, and for directing the same, in which the bearings are ground on a first grinding machine and then the camshaft is then directed on the first grinding machine and the cams of the camshaft on a second grinding machine pre-ground and finish ground. Method for grinding bearings and cams a built camshaft, with the camshaft made of a steel tube and the cam, and for directing the same, in which the bearings are ground on a first grinding machine and the cams of the camshaft on a second grinding machine pre-ground and finish ground and the camshaft after roughing and / or finish grinding the cams on the second grinding machine is directed. A method according to claim 5 or 6, wherein the Pre-grinding the cams of the camshaft on a first station the second grinding machine and the finish grinding of the cams of Camshaft on a second station of the second grinder respectively. Method according to one of claims 1 to 7, wherein during the Finish grinding the bearings in the area of the camshaft Bearings by supports, especially through lunettes, supported is and for straightening the supports except Intervention be brought by the bearing. The method of claim 8, wherein the supports after pre-grinding the cams to the areas of the respective Lagerstellen be reinstated and then the Cocks are finished. A method according to claim 5 or 6, wherein the Cam of the camshaft on the second grinding machine with employees supports, especially lunettes, pre-ground, then the supports at least in one be solved in the middle region of the camshaft and then the Straightening takes place, after which the supports in be reopened to this area of the depository and then the Cocks are finished. A method according to any one of claims 1 to 10, wherein judging at least for one of the bearings in the central region of the camshaft a true running value or runout value is measured. The method of claim 11, wherein the camshaft based on the measured concentricity value or concentricity deviation value is directed. Method according to one of claims 1 to 12, wherein the Aligning with rotating camshaft with a speed of 50 to 200 revolutions per minute. The method of claim 13, wherein the Camshaft in the area of their middle bearing point during the A straightening force is exercised. Method according to one of claims 1 to 12, wherein the Alignment is done with the camshaft stopped, with the first Depository with the highest Concentricity deviation is determined and a straightening force in this bearing, relative to the circumference, initiated in the region of the radial position becomes, at which this highest Runout exists. Method according to one of claims 1 to 15, wherein the Camshaft when straightening at least partially over the Yield strength of the material of the steel tube is suppressed and then the Deflection of the camshaft gradually up to approximately 0 mm is withdrawn. The method of claim 4, wherein the straightening done on the first station. The method of claim 4, wherein the straightening done on the second station. Device for grinding bearings ( 2 ) and cams ( 3 ) a built camshaft ( 1 ), wherein the camshaft consists of a steel tube and the cam, and for straightening the same, in particular for carrying out the method according to one of claims 1 to 18, which comprises a grinding machine ( 4 ) with a straightening device integrated in the grinding machine ( 6 ) for straightening the camshaft ( 1 ) after a grinding operation. Apparatus according to claim 19, in which a concentricity measuring device ( 5 ) for measuring a concentricity value or a runout value of the camshaft ( 1 ) in the grinding machine ( 4 ) is integrated. Device according to Claim 20, in which the grinding machine ( 4 ) one on a machine bed ( 8th ) worn grinding headstock ( 7 ) with at least two in a respective grinding position einschwenkbaren grinding wheels ( 9 . 10 . 23 . 24 ) and a workpiece headstock ( 12 ) and a tailstock ( 13 ), which are formed so that the camshaft ( 1 ) between peaks ( 14 ) is clamped and the Rundlaufinesseinrichtung ( 5 ) on the wheelhead ( 7 ) or on the machine bed ( 8th ) and the straightening device ( 6 ) on the wheelhead ( 7 ) are attached. Device according to one of claims 19 to 21, in which the grinding machine ( 4 ) a first station ( 15 ) and a second station ( 16 ) having. Device according to Claim 22, in which the first station ( 15 ) is designed so that on it a) the finish grinding of the bearings ( 2 ) of the camshaft ( 1 ) or b) the finish grinding of the bearings ( 2 ) and the pre-grinding of the cam ( 3 ) is feasible. Apparatus according to claim 22 or 23, wherein in the first station ( 15 ) the straightening device ( 6 ) is arranged. Device according to one of Claims 22 to 24, in which the second station ( 16 ) is designed so that on it the pre-grinding and / or the finish grinding of the cam ( 3 ) of the camshaft ( 1 ) is feasible. Device according to one of claims 22 or 23, in which in the second station ( 16 ) the straightening device ( 6 ) is arranged. Device according to one of claims 19 to 26, in which the straightening device ( 6 ) a roll straightening head ( 17 ), which is designed such that the straightening with rotating camshaft ( 1 ) is executable. Device according to claim 27, in which the roll straightening head ( 17 ) two rollers mounted in the front area ( 18 ), on the wheelhead ( 7 ) and in particular in the X direction on the bearings ( 2 ) of the camshaft ( 1 ) bar is. Device according to one of claims 19 to 26, in which the straightening device ( 6 ) a printing element straightening head ( 19 ), which is designed so that the straightening when the camshaft is stationary ( 1 ) is executable. Apparatus according to claim 29, wherein the printing element straightening head ( 19 ) a stored prism ( 20 ) with a recess ( 21 ) for introducing a straightening force over at least two circumferentially spaced locations in one of the bearing points ( 2 ) of the camshaft ( 1 ) having. Apparatus according to claim 29, wherein the printing element straightening head ( 19 ) a pressure element having a flat surface ( 22 ) for introducing a straightening force via a point in one of the bearing points ( 2 ) of the camshaft ( 1 ) having.