DE102004009352B4 - Device for producing a finished contour of a workpiece by grinding and method thereto - Google Patents

Abstract

The invention relates to a method for producing a finished contour of a workpiece contour having a blank contour by grinding in several operations, in which the blank contour of the workpiece is abraded by a predetermined amount in each operation, so that after the last operation, the finished contour of the workpiece is present. In order to achieve such a method that the time required for the production of a finished contour is shortened as far as possible and yet a tool breakage or an inadmissible component heating is prevented, the following method steps are proposed: DOLLAR A a) before the beginning of the grinding process, the blank contour of Workpiece measured; DOLLAR A b) the measured values are transmitted directly or indirectly to a control unit (4) for controlling the delivery of an abrasive of a grinding machine (3); DOLLAR A c) in dependence on these measured values, a grinding program adapted to the actual blank contour is calculated, in which the control of the delivery of the grinding means of the grinding machine (3) takes into account the actual blank contour in such a way that the abrasive material with immediate delivery speed the actual blank contour or up to a predefinable safety distance is approached to the actual blank contour.

Description

The The invention relates to a method for producing a finished contour a workpiece having a blank contour by grinding in several Operations, in which the blank contour of the workpiece in each operation to a specifiable measure ground off is so that after the last operation, the finished contour of the workpiece is present. The invention also relates to a device for grinding a finished contour of cam of a camshaft with a grinding machine and a controlling this controlling means, wherein by the control means Abrasive programs can be specified, which default values with regard to the grinding parameters rotational speed of the abrasive and / or the workpiece, feed, Delivery and axial position of the workpiece include.

From the prior art, different methods and apparatus for producing a finished contour of a workpiece by grinding in several operations are known. For example, from the DE 29 35 897 A1 a first embodiment is known in which the contour of the workpiece to be ground during the grinding process is measured. In a modified second embodiment, the contour is measured immediately after a successful first grinding operation and thus calibrated the grinding wheel for a further grinding operation by comparing the measurement with the Schleifbockzustellung for the first grinding operation.

From the DE 37 02 594 C3 a method for grinding two or more cams of a camshaft is known, in which a measuring device is moved up to the cam, while a last revolution of the cam is unwound at the end of a grinding interval, and that subsequently with further rotation of the cam, the measurement is made. In each case the base circle diameter or the sum of the base circle diameter and the maximum elevation value of the ground contour of the cam is measured.

Finally, out of the DE 40 23 587 C2 A method is known in which the workpiece contour is measured during grinding and the infeed of the grinding wheel is regulated inline with these measured values.

at The above-mentioned method according to the prior art will not the blank contour of the workpiece measured before the grinding process, but the measurements find while the grinding process instead.

at the machining of workpieces by means of grinding must the blanks have a contour within a tolerance band an oversize in comparison to the measure of Having prefabricated components. Because the blanks differ the tolerance band fulfill, is the grinding program usually designed so that a groping approach to the material achieved becomes what unnecessary Air overflows (air loops) leads, where no material is removed. These air overflows require unnecessary manufacturing time.

specially for the production of assembled camshafts are the cams and other functional components of camshafts according to tolerance specifications manufactured as blanks and mounted on the camshaft. It arises a tolerance band in which the outer contour of the unpolished mounted cams / functional components moved. This contour is called Blank contour designated. This blank contour must have a grinding allowance.

in the After installation, the cams, bearing points and, if necessary, additional functional surfaces ground. The grinding allowance is removed. The allowance is required to get a really polished surface at the end of the machining and certainly not to fall below the target contour (finished contour).

The grinding is carried out according to the prior art in several operations in such a way that the grinding wheel is moved very quickly programmatically very fast to the taking into account the allowable tolerance outer circumference of the blank contour and then the actual grinding process begins. In the actual grinding process, the grinding wheel is driven programmatically with a predetermined feed at a given speed to the specified size of the finished contour to be ground. This feed movement is relatively slow, so that the workpiece to be ground does not overheat and the grinding wheel is not damaged. Depending on the thickness of the layer to be ground, the feed rate at the beginning is set faster (roughing) and later more slowly (finishing, fine finishing). When the nominal contour is reached, no further delivery takes place. The workpiece is cleared. After a certain period of time Freifunkens, the workpiece has the specified size, ie the finished contour and the process is terminated by quickly returning the grinding wheel. The multiple successive feed movements are referred to as multiple operations.

The for the Control of the grinding wheels required programs Values for axial and radial feeds (Workpiece rotational speeds) as well as radial infeeds, with which the grinding wheels to the workpiece be approached. There are grinding machines with one and Grinding machines with multiple spindles.

adversely in the previously known control programs for grinding machines is ever according to the size of the blank contour, this means depending on the actual Grinding allowance of unpolished functional component, the grinding wheel over partially several 1/10 mm, despite the lack of contact with the workpiece, very slowly moved up to the blank contour of the functional component. This process is often referred to in the art with air loops. The duration of air grinding depends on the position of the blank contour different in the tolerance field. As a result, in many cases unnecessarily much time for the grinding needed. additionally leads the high quality requirement for safer manufacturing processes, that the allowable tolerance range is not fully exhausted becomes. As a result, in the majority of cases, unnecessarily long air loops occur. Indeed can not be dispensed with the air grinding, because again and again individual blanks the largest permissible blank contour or could have.

The The object of the invention is a method and a device specify, with or with the for the production of a finished contour a workpiece having a blank contour by grinding in several operations needed Time as far as possible shortened and yet prevents tool breakage or improper component heating becomes.

Regarding of the method, this object is achieved by a method with the Characteristics of claim 1 or claim 2 solved. advantageous Primary and Further Education of the method are given in the subclaims 2 to 9. in the With regard to the device, the object is achieved by a device solved with the features of claim 10.

By the above solution is advantageously achieved that an unnecessary, the processing time extending Air loops is avoided. By the measure that measuring is functional separated from the grinding machine will continue to be advantageous a further reduction in working hours on the relative to a testing device reached expensive grinding machine.

The The invention relates in a specific embodiment to a method for Producing a finished contour of a blank contour having workpiece by grinding in several operations, in which the blank contour of the workpiece is abraded by a predetermined amount in each operation, so that after the last operation, the finished contour of the workpiece is present.

• a) vor Beginn des Schleifprozesses wird die Rohteilkontur des Werkstückes gemessen;
• b) die ermittelten Messwerte werden direkt oder indirekt an eine Steuereinheit zur Steuerung der Zustellung eines Schleifmittels einer Schleifmaschine übermittelt;
• c) in Abhängigkeit von diesen Messwerten wird ein auf die tatsächliche Rohteilkontur angepasstes Schleifprogramm errechnet, bei dem die Steuerung der Zustellung des Schleifmittels der Schleifmaschine unter Berücksichtigung der tatsächlichen Rohteilkontur in der Weise erfolgt, dass das Schleifmittel mit maximaler Zustellgeschwindigkeit unmittelbar an die tatsächliche Rohteilkontur oder bis zu einem vorgebbaren Sicherheitsabstand an die tatsächliche Rohteilkontur herangefahren wird.

According to a first embodiment of the invention, the method has the following method steps:

• a) before the beginning of the grinding process, the blank contour of the workpiece is measured;
• b) the measured values determined are transmitted directly or indirectly to a control unit for controlling the delivery of an abrasive of a grinding machine;
• c) as a function of these measured values, a grinding program adapted to the actual blank contour is calculated, in which the control of the delivery of the abrasive of the grinding machine taking into account the actual blank contour in such a way that the abrasive at the maximum feed rate directly to the actual blank contour or is approached to a predetermined safety distance to the actual blank contour.

• a) vor Beginn des Schleifprozesses wird die Rohteilkontur des Werkstückes gemessen;
• b) die ermittelten Messwerte werden direkt oder indirekt an eine Steuereinheit zur Steuerung der Zustellung eines Schleifmittels einer Schleifmaschine übermittelt;
• c) in Abhängigkeit von diesen Messwerten wird ein vorgegebenes und abgespeichertes Schleifprogramm ausgewählt, bei dem die Steuerung der Zustellung des Schleifmittels der Schleifmaschine an die tatsächliche Rohteilkontur im Vergleich zu den übrigen auswählbaren Schleifprogrammen in der Weise am besten angepasst ist, dass das Schleifmittel mit maximaler Zustellgeschwindigkeit unmittelbar an die tatsächliche Rohteilkontur oder bis zu einem vorgebbaren Sicherheitsabstand an die tatsächliche Rohteilkontur herangefahren wird.

In a second embodiment of the invention, the method has the following method steps:

• a) before the beginning of the grinding process, the blank contour of the workpiece is measured;
• b) the measured values determined are transmitted directly or indirectly to a control unit for controlling the delivery of an abrasive of a grinding machine;
• c) in response to these measurements, a predetermined and stored grinding program is selected in which the control of the delivery of the grinding means of the grinding machine to the actual blank contour in the best way compared to the other selectable grinding programs is adapted that the abrasive is moved up to the actual blank contour with maximum feed rate directly or up to a predetermined safety distance to the actual blank contour.

• • eine Messeinrichtung zum Messen der zu schleifenden Rohteilkontur des Werkstückes;
• • ein Prozessrechner zur Bestimmung und/oder Auswahl eines oder mehrerer Schleifprogramme;
• • eine erste Datenübertragungseinrichtung zwischen der Messeinrichtung und dem Prozessrechner sowie eine zweite Datenübertragungseinrichtung zwischen dem Prozessrechner und der Steuereinrichtung, wobei die von der Messeinrichtung gemessenen Messwerte der Rohteilkontur über die erste Datenübertragungseinrichtung dem Prozessrechner zuführbar sind, in Abhängigkeit von diesen Messwerten im Prozessrechner mindestens ein Schleifprogramm bestimmt und/oder ausgewählt wird, bei dem das Schleifmittel mit maximaler Zustellgeschwindigkeit unmittelbar an die tatsächliche Rohteilkontur oder bis zu einem vorgebbaren Sicherheitsabstand an die tatsächliche Rohteilkontur des Werkstücks herangefahren wird und dieses Schleifprogramm über die zweite Datenübertragungseinrichtung der Steuereinrichtung zuführbar ist und die Schleifmaschine von der Steuereinrichtung entsprechend dem bestimmten und/oder ausgewählten Schleifprogramm steuerbar ist.

With regard to the device according to the invention according to the preamble of claim 10, the object underlying the invention is achieved in that at least the following device components are provided:

• A measuring device for measuring the workpiece contour to be ground;
• A process computer for determining and / or selecting one or more grinding programs;
• A first data transmission device between the measuring device and the process computer and a second data transmission device between the process computer and the control device, wherein the measurement values of the blank contour measured by the measuring device can be supplied to the process computer via the first data transmission device determines at least one grinding program depending on these measured values in the process computer and / or is selected, in which the abrasive is moved up to the actual blank contour or to a predefinable safety distance to the actual blank contour of the workpiece at maximum feed rate and this grinding program on the second data transmission device of the control device can be fed and the grinding machine of the control device accordingly the particular and / or selected grinding program is controllable.

there it is first irrelevant whether the data connection by means of a fixed connection, for example about Cable, radio, etc., or by means of a non-fixed connection, for example via a Floppy disks or markings on the workpiece - the respective camshaft - etc., is shown.

In a preferred embodiment Both data connections are fixed connections in the form of cables educated. The data transmission over the usual protocols or bus systems used in industrial control technology, such as Profibus or Interbus. The process computer can an industrial-grade personal computer, a microcomputer or another data processing device.

at In the invention, the grinding programs are performed in the following manner determined: The measurement of the blank contour is determined directly, to what extent the Grinding wheel with maximum feed rate to be sanded workpiece can be approached. Ideally, this is the grinding wheel with maximum infeed speed right up to the blank contour moved up. But it can also be a precaution for the grinding wheel not completely be approached to the measured blank contour, but a Air loops over a distance of 0.02 mm to 0.1 mm are preset. The size determines from the measuring accuracy of the measuring system for measuring the Contours. From the measured blank contour is simultaneously the Grinding, this means the thickness of the material to be ground, determined. It will become the different areas for the roughing, finishing and fine finishing grinding and thus the associated Delivery speeds set. Here, the material including the hardness and the geometric design of the workpiece to be ground of Importance. thin Components can not so much heat lead away like thick solid components. Depending on the material condition different amounts of heat Released at the same feed rate. In the same way be, depending on the possibility the machine, the speeds of workpiece and tool set. For the interpretation of such programs are the expert criteria and Defaults known.

With the method according to the invention is, contrary to the prior art, the Schleifmaßmaß accordingly the measuring accuracy of the measuring system known. This will after the usual in grinding technology Process the grinding program with the optimum delivery program certainly. This means: In each case, exactly adjusted, the fastest possible delivery is determined, with no overheating yet of the workpiece takes place and the finished contour is reached exactly. For the determination the delivery programs in which the feed per revolution of the workpiece specified is the energy and power input associated with the grinding process essential, thus grinding errors, such as grinding burn and soft skin formation, can be prevented. The allowable feed rate is also material-dependent.

by virtue of the exact knowledge of the layer thickness to be abraded is at the invention, a precise coordination of the roughing and finishing and fine sanding operations allows. The grinding program adapted in each case to the grinding allowance to be abraded leads often to optimized and shortened grinding times, since e.g. the delivery route for The roughing can be increased in comparison to the finishing, while the Air grinding phase is reduced to a minimum or even eliminated.

In a preferred embodiment The procedure involves a large number of precalculated programs their respective assignment to a specific blank contour in the Process computer stored. While of the manufacturing process is the respectively measured blank contour assigned program selected by the process computer.

In Another advantageous development of the method is even possible to calculate the grinding programs in-line. As calculation criterion can Here the energy and / or current account are used. there become dependent of layer thickness and other usual Parameters the maximum permissible Infeed paths per revolution of the workpiece and mathematical basis From this the grinding program with the delivery program determines which the processing time is minimized.

The inventive method is both for Camshafts with any number of cams as well as others applicable to grinding functional components. It can be for each Component a separate grinding program or in simpler cases too for groups of functional components the same grinding program can be selected. The transfer The data for controlling the grinding machine takes place either in the block all for needed the appropriate parts Grinding programs or piece for pieces as needed immediately before delivery of the grinding wheel to the corresponding Position.

In An advantageous development of the invention, the components with markings, such as serial numbers, barcodes or similar provided, which are linked in the process computer with the measurement data of the blank contours. This data can then also be transmitted off-line to the control of the grinding machine. When the waves enter the grinding machine, these codes become read and from it the associated Programs loaded. Here is the mark in a development directly the marking of the grinding programs to be used.

On the basis of in the 1 and 2 embodiments shown, the invention is explained in detail.

1 shows the schematic structure of the inventive device for grinding camshafts.

In 2 the cam and the position of the finished part contour as well as the lower and upper tolerance limit of the blank contour are shown.

In the 1 is shown schematically as the camshaft 1 with the functional component to be ground 2 , For example, the cam, located in the measuring station for measuring the blank contour at the end of the assembly line (not shown here). With a sensor used for measuring 13 , here in the example a probe or a laser triangulation device, the profile data of the cam 2 detected. The measured values are transmitted via the signal line 9 a process computer 5 fed. The process computer 5 has a data store 7 for storing a plurality of grinding programs, which in particular include delivery programs. Furthermore, the process computer has 5 via an arithmetic unit 6 , a second data store 8th and corresponding internal data lines 10 which are usually realized by a data bus. In the calculator 6 of the process computer 5 is due to the input on the signal line 9 , the measured value, a corresponding grinding program from the data memory 7 selected and in the data store 8th stored. Via the data line 11 is the corresponding grinding program, which in particular includes the corresponding Zustellprogramm to the controller 4 the grinding machine 3 transfer.

Parallel to this, the camshaft 1 with a corresponding transfer handling 14 , for example a robot, into the grinder 3 introduced for editing. Via the control signal lines 12a and 12b The data required to control the grinding machine are transmitted and the camshaft 1 Ground according to the selected control program.

In a modification of the method described above, the camshaft is clearly marked after the measurement of the blank contour (eg barcode) and via the control line 12a Also, a detection signal for detecting which camshaft is currently inserted in the grinding machine, to the controller 4 transfer. The marking carries the information about the measured blank contour or the grinding program to be selected. The control 4 then selects the corresponding grinding program from an assignment of detection signals to grinding programs.

In an alternative embodiment, the controller requests 4 , based on the detection signal, the grinding program from the process computer 5 at.

According to the invention, the process computer 5 and the controller 4 into a computing unit 15 be integrated. However, the exact configuration of the arithmetic unit can be very different. Also, the data lines 9 . 10 . 11 . 12a . 12b be integrated into a bus system, as is common in mechanical engineering.

With reference to Table 1 and the 2 a comparison of the prior art for the method according to the invention. As an example, a camshaft 1 with cams 2 selected in which the oversize of the blanks to be abraded within the envelopes 17 to 18 lies. This excess of blanks after assembly, based on the finished part contour 16 , also called allowance, varies in production due to the example in an interval of finished part contour plus 0.1 mm (Envelope 17 ) to finished size plus 0.5 mm (envelope 18 ). The oversize must be at all points of the outer circumferential contour of the cam within the range between the envelope 17 and the envelope 18 lie. In the example selected, the actual excess at any point in the contour is 0.35 mm.

The Delivery of the grinding wheel must be done so that in no case the grinding wheel with highest Speed, as for the approach of the disc is used to the workpiece, immersed in the workpiece surface.

In the prior art, as shown in the left half of Table 1, therefore, the grinding wheel becomes the envelope 18 approached for the greatest possible excess. Following this, certain delivery routes are run per revolution of the workpiece, until in the last step, here the 7 , Rotation, the free spark with 0 mm delivery takes place and the workpiece on the finished part contour 16 was ground.

To In the prior art, this means 7 deliveries with a total delivery path of 0.5 mm. The entire process time is then approx. 7 seconds.

As However, as the table shows, the delivery was made for one Way of 0.15 mm with for the grinding adapted speed performed, though even no abrading of material has occurred. This process will also referred to in the art with air loops.

With the method according to the invention, as it is in the right half Table 1, this air grinding is completely eliminated. The delivery is made directly to the envelope of the measured oversize, here +0.35 mm. In 5 further revolutions of the workpiece is the grinding operation completed. The saving in process time in the example mentioned is approximately 2 seconds per cam.

As is further shown in Table 1, when using the the method according to the invention Deliveries for the first 2 turns larger than in the prior art. Here is an advantageous development of the method shown in which the feed rate in dependence adapted to the thickness of the excess becomes. For excesses, the are relatively large, As a rule, grinding takes place at a high infeed speed (rough grinding). Only with small oversizes a lowering of the infeed speed (finishing, fine finishing grinding or sparking out). The high infeed speed during rough grinding must be sized so that not too much power is introduced into the workpiece and, accordingly, no overheating of the workpiece he follows. Thus, in the example, the maximum value is the excess of 0.500 mm, a delivery of 0.400 mm per 4 revolutions to an allowance of 0.100 mm and a corresponding power input provided. However, the excess is only 0.350 mm, this delivery can be up to the allowance of 0.100 mm even increased where the total delivery is the value of the original Do not exceed the power input may. As a measure of this, the Time span volume be used.

Tabelle 1

Table 1

About the described advantages addition, the inventive method provides even more important benefits. So allows the measurement before the Sanding a sorting of waves where the blank contour the functional components are already too small, i. no longer in the tolerance band lies. In this case, the wave can also be further processed no longer become a good part, so a grinding no longer necessary is. As a result, rejects are no longer processed and the one for that force Saved processing times and costs.

The even greater advantage is also to be seen in the fact that workpieces with an oversize, over the maximum envelope 18 can be processed without consequential damage. This makes it possible to lower the tolerance requirements partially or for the time of certain production problems.

Farther can the quality of the blanks are determined with statistical width, so that a early detection of emerging problems in upstream manufacturing processes possible becomes.

It It is obvious that the method described here and the Device described here also for other components than built Camshafts can be applied. The application can, for example, too for cast or forged camshafts, crankshafts, control shafts as well the grinding of bearings of transmission shafts done.

1

camshaft

2

Functional component, cam

3

grinding machine

4

control

5

process computer

6

calculator

7

data storage

8th

data storage

9

signal line

10

internal data line

11

data line

12a

Control signal line

12b

Control signal line

13

sensors, probe

14

Feed camshaft in grinding machine, transfer handling

15

computer unit

16

Finished part contour

17

envelope, lower tolerance limit of the blank contour

18

envelope, upper tolerance limit of the blank contour

Claims (10)

A method for producing a finished contour of a workpiece having a blank contour by grinding in several operations, in which the blank contour of the workpiece is abraded by a predetermined amount in each operation, so that after the last operation, the finished contour of the workpiece is present, characterized by the following method steps: before starting the grinding process, the blank contour of the workpiece is measured; b) the measured values determined are sent directly or indirectly to a control unit ( 4 ) for controlling the delivery of an abrasive of a grinding machine ( 3 ) transmitted; c) as a function of these measured values, a grinding program adapted to the actual blank contour is calculated, in which the control of the delivery of the abrasive of the grinding machine ( 3 ) takes place taking into account the actual blank contour in such a way that the abrasive is moved up to the actual blank contour with maximum feed speed directly to the actual blank contour or up to a predefinable safety distance. A method for producing a finished contour of a workpiece having a blank contour by grinding in several operations, in which the blank contour of the workpiece is abraded by a predetermined amount in each operation, so that after the last operation, the finished contour of the workpiece is present, characterized by the following method steps: before starting the grinding process, the blank contour of the workpiece is measured; b) the measured values determined are sent directly or indirectly to a control unit ( 4 ) for controlling the delivery of an abrasive of a grinding machine ( 3 ) transmitted; c) in dependence on these measured values, a predetermined and stored grinding program is selected, in which the control of the delivery of the abrasive of the grinding machine ( 3 ) is best adapted to the actual blank contour compared to the other selectable grinding programs in such a way that the abrasive is moved up to the actual blank contour or to a predefinable safety distance to the actual blank contour with maximum feed rate. A method according to claim 1 or 2, characterized in that the determined measured values of the blank contour in the context of the indirect transmission to the control unit ( 4 ) first to a process computer ( 5 ), which carries out the calculation of the grinding program adapted to the actual blank contour or the selection of the predetermined and stored grinding program. Method according to claim 2, characterized in that that at a non-changeable Grinding program with several grinding operations, depending on the determined measured values the blank contour, a first grinding operation skipped becomes. Method according to claim 4, characterized in that that in addition to the first grinding operation more, skipped to the first subsequent grinding operations become. Method according to one of claims 1 to 5, characterized that the abrasive with maximum feed rate to at a maximum safety distance of 0.1 mm and a minimum of 0.02 mm is moved to the blank contour. Method according to one of claims 1 to 6, characterized that in dependence from the difference between blank contour and finished contour the delivery speed while The grinding is sized so that it is as large as possible and at the same time no overheating of the workpiece he follows. Method according to one of claims 1 to 7, characterized in that means are provided with which by the measuring device ( 13 ) measured values and / or in a process computer ( 5 ) certain grinding programs are assigned directly or indirectly to the individual workpiece. A method according to claim 8, characterized in that further means are provided, which associate the workpiece with the measurements and / or the grinding programs containing coding and that further means are provided, which encode the insertion of the workpiece in the grinding machine ( 3 ) read. Device for grinding a finished contour of cams ( 2 ) a camshaft ( 1 ) with a grinding machine ( 3 ) and a control device ( 4 ), whereby the control device ( 4 ) Grinding programs can be specified, which contain default values with regard to the grinding parameters rotational speed of the abrasive and / or the workpiece, feed, infeed and axial position of the workpiece, characterized in that at least the following components are provided: 13 ) for measuring the raw part contour of the workpiece to be ground; • a process computer ( 5 ) for determining and / or selecting one or more grinding programs; A first data transmission device ( 9 ) between the measuring device ( 13 ) and the process computer ( 5 ) and a second data transmission device ( 11 ) between the process computer ( 5 ) and the control device ( 4 ), whereas those of the measuring device ( 13 ) measured values of the blank contour over the first data transmission device ( 9 ) the process computer ( 5 ) can be supplied, depending on these measured values in the process computer ( 5 ) at least one grinding program is determined and / or selected, in which the abrasive material is moved up to the actual blank contour contour or up to a predefinable safety distance to the actual blank contour of the workpiece at maximum feed rate, and this grinding program via the second data transmission device ( 11 ) of the control device ( 4 ) and the grinding machine ( 3 ) from the control device ( 4 ) is controllable according to the determined and / or selected grinding program.