DE102004009352A1 - Process and assembly to grind complex curved metal shape e.g. automotive crankshaft to final dimensions has sensor linked to control unit - Google Patents

Abstract

In a process to grind a crankshaft to its final dimensions, the grinding assembly has a sensor (13) in touch with the crankshaft and a data processing unit holding a record of the target dimensions. The data processing unit is coupled to and regulates operation of the grinding tool. Also claimed is a commensurate grinding tool.

Description

The The invention relates to a device according to the preamble of the claim 1 and a method according to the preamble of claim 8.

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 done according to the prior art in several operations in the way that the grinding wheel is programmatically very fast under consideration the permissible Tolerance extremely possible outer periphery the blank contour is moved up and then the actual grinding process begins. During the actual grinding process is the grinding wheel with a predetermined feed at a given Speed on nominal dimension of Programmatically driven to be ground ready contour. This delivery movement takes place relatively slowly, so that the workpiece to be ground does not overheat and the grinding wheel is not damaged. Depending on the thickness of the To be ground layer is the speed of delivery at the beginning faster (roughing) and later slower (finishing, fining) set. Upon reaching the target contour is no further delivery. The workpiece becomes free radioed. After a certain duration of the free fall, this indicates workpiece the nominal size, i.e. the finished contour on and the process is by fast return the grinding wheel finished. Here are the multiple successively following delivery movements 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 device and a method specify, with or with the for 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.

With regard to the device this object is achieved by a device having the features of claim 1. Advantageous embodiments and further developments are described in claims 2 to 7. With regard to the method, the object is achieved by a method with the characteristics of the godfather claim 8 solved. Advantageous developments of the method are specified in the claims 9 and 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 to a device in a specific embodiment for grinding a finished contour of cam of a camshaft with a grinding machine and a control device controlling it, wherein grinding programs can be predetermined by the control device, which default values with regard to the grinding parameters speed of Abrasive and / or the workpiece, feed, delivery and Axial position of the workpiece include.

• • eine Messeinrichtung zum Messen der zu schleifenden Rohteilkontur des Werkstückes;
• • einen 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 und über die zweite Datenübertragungseinrichtung der Steuereinrichtung zuführbar ist und die Schleifmaschine von der Steuereinrichtung entsprechend dem bestimmten und/oder ausgewählten Schleifprogramm steuerbar ist.

According to the invention, the device preferably has the following components:

• 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 and can be fed to the control device via the second data transmission device and the grinding machine can be controlled by the control device in accordance with the determined and / or selected grinding program.

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.

Further The invention relates to a method for producing a finished contour a workpiece having a blank contour by grinding in several Operations, preferably on cams of a camshaft, 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 übermittelt;
• c) in Abhängigkeit von diesen Messwerten wird entweder ein auf die tatsächliche Rohteilkontur angepasstes Schleifprogramm errechnet, bei dem die Steuerung der Zustellung des Schleifmittels der Schleifmaschine unter Berücksichtigung der tatsächlichen Rohteilkontur erfolgt, oder 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 am besten angepasst ist.

According to the invention, the following method steps are carried out in this method:

• 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;
• c) depending on these measured values, either 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, or a predetermined and stored grinding program is selected, in which the control of the delivery of Grinding machine of the grinding machine is best adapted to the actual blank contour compared to the other selectable grinding programs.

The grinding programs are determined in the following manner: From the measurement of the blank contour, it is determined directly to what extent the grinding wheel can be moved up to the workpiece to be ground at the maximum feed rate. Ideally, the grinding wheel is moved up to the blank contour with maximum feed rate. However, for safety's sake, the grinding wheel can not be completely moved up to the measured blank contour, but an air grinding over a distance of 0.02 mm to 0.1 mm can be preset. The size is determined by the measuring accuracy of the measuring system for measuring the contours. At the same time, the grinding allowance, that is to say the thickness of the material to be abraded, is determined from the measured blank contour. From this, the various areas for the roughing, finishing and fine finishing grinding and thus the associated delivery speeds are determined. Here is the material including the hardness and the geometric design of the workpiece to be ground importance. Thin components can not dissipate as much heat as thick solid components. Depending on the nature of the material, different amounts of heat are released at the same infeed speed. In the same way, depending on the possibility of the machine, the speeds of workpiece and tool set. For the interpretation of such programs, those skilled in the criteria and specifications are 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 procedure described above, the camshaft is clearly marked after the measurement of the blank contour (eg bar code) 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. Subsequently, certain feed paths are moved per revolution of the workpiece until, in the last step, in this case the 7th revolution, the free sunk with a 0 mm infeed takes place and the workpiece is placed 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 further shown in Table 1, when using the method according to the invention, the deliveries for the first 2 revolutions are greater than in the prior art. Here is an advantageous one Development of the method shown, in which the feed rate is adjusted in dependence on the thickness of the excess. For oversize, which are relatively large, is usually ground with high infeed speed (rough grinding). Only with small excesses is a reduction in the delivery speed (finishing, fine finishing grinding or sparking). The high infeed speed during rough grinding must be such that not too much power is introduced into the workpiece and accordingly no overheating of the workpiece takes place. Thus, in the example, as a maximum value, with an oversize 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 is provided. However, if the oversize is only 0.350 mm, this infeed may even be increased to 0.100 mm, where the total delivery may not exceed the value of the original contribution. As a measure of this, the Zeitspanvolumen can 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)

Device for producing a finished contour of a workpiece having a blank contour by grinding in several operations, preferably on cams ( 2 ) a camshaft ( 1 ), comprising a grinding machine ( 3 ), which has an abrasive for grinding one of the difference between blank contour and finished contour corresponding oversize, and a control device ( 4 ) for driving the grinding machine ( 3 ), characterized in that a measuring device ( 13 ) is provided for measuring the actual blank contour of the workpiece, which by means of at least one data transmission device ( 9 . 10 . 11 . 12a . 12b ) with the control device ( 4 ) is coupled directly or indirectly, so that the measuring equipment ( 13 ) measured values of the control device ( 4 ) and from these measured values from the control device ( 4 ) at least default values for the control of the delivery of the abrasive can be determined. Apparatus according to claim 1, characterized in that the measuring device ( 13 ) separately from the grinding machine ( 3 ) and between the measuring device ( 13 ) and the grinding machine ( 3 ) A transport device is provided for the workpiece transport. Apparatus according to claim 1 or 2, characterized in that between the measuring device ( 13 ) and the control device ( 4 ) a process computer ( 5 ), to which the measured values of the measuring device ( 13 ) via a first data transmission device ( 9 ) can be supplied, so that by the process computer ( 5 ), depending on the measured values, a grinding program suitable for the present grinding task can be selected, which is controlled via a second data transmission device ( 11 ) to the control device ( 4 ) is transferable. Device according to one or more of claims 1 to 3, characterized in that means are provided with which by the measuring device ( 13 ) measured values are assigned directly or indirectly to the individual workpiece. Apparatus according to claim 4, characterized in that the means to assign the workpiece a coding containing the measured values and that further means are provided which the coding when inserting the workpiece in the grinding machine ( 3 ) read. Device according to one of claims 1 to 5, characterized in that means are provided, with which workpieces after measuring the blank contour in the measuring device ( 13 ) are then not supplied to a further processing if the measured blank contour falls below the finished contour beyond a permissible tolerance field. Device for grinding a finished contour of cams ( 2 ) a camshaft ( 1 ) with a grinding machine 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 and 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. Method for producing a finished contour of a workpiece having a blank contour by grinding in several operations, preferably on cams ( 2 ) a camshaft ( 1 ), 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 steps: a) before the beginning of 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 ) transmitted; c) depending on these measured values, either a grinding program adapted to the actual blank contour contour is calculated, in which the control of the feed of the grinding means of the grinding machine ( 3 ) taking into account the actual blank contour, or 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. Method according to claim 8, 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 9, characterized in that that in addition to the first grinding operation more, skipped to the first subsequent grinding operations become.