EP1419030B1 - Method and device for centerless cylindrical grinding - Google Patents

Abstract

During centerless cylindrical grinding, attention must be paid to the fact that the workpiece ( 3 ) is placed in a very specific position between the grinding wheel ( 1 ), the regulating wheel ( 2 ) and the support guide ( 4 ). The optimal position of the workpiece ( 3 ) initially set cannot be maintained as a result of the progression of the grinding process and the changes caused by said process in the diameter and contour of the workpiece ( 3 ). The invention provides a solution to said problem, whereby height adjustment and/or the oblique position of the support guide ( 4 ) are automatically modified in accordance with the progression of the grinding process and during said grinding process with the purpose of achieving operationally optimal readjustment. The progression of the grinding process can be detected using measuring techniques, e.g. by measuring the diameter of the workpiece ( 3 ) or its deviation from roundness and using said measurement as output variable for adjusting the support guide ( 4 ).

Description

The invention relates to a method for centerless cylindrical grinding, according to the preamble of claim 1 and a device according to the preamble of Claim 5.

Such a method and apparatus are known from EP 498 763 A.

A procedure of this kind, which is often referred to as "centerless procedure" in company practice. is designated, is known for example from DE 32 02 341 A1. In this document it is stated that for optimum grinding results Required position of the workpiece between the grinding wheel, the regulating wheel and the support ruler is not easy to adjust. As the regulating wheel also To cause the feed of the workpiece, it has a slight from the horizontal tilted location. The workpiece is in a not exactly defined Way between the regulating wheel and the support ruler; it will be in this position pressed in through the grinding wheel. It is advantageous, if that too Support ruler is slightly tilted out of the horizontal. The relevant settings When preparing the machine for the grinding process are the center distance between the grinding wheel and the regulating wheel as well as the height adjustment of the support ruler. The best for any workpiece diameter appropriate center distance of grinding wheel and regulating wheel, and this must again the most suitable height adjustment of the support ruler found out become. The tuning of these settings requires a lot of experience.

So when converting the machine to a new type of workpiece not each time awkward a setting by hand, if necessary, by trial and error and test runs, must be made in DE 32 02 341 A1 already proposed, each center distance between the grinding wheel and the Regulating disc assign a certain height adjustment of the support ruler. For this purpose, the regulating wheel is in the usual way in a headstock slide stored, which can be made in the direction of the grinding wheel. A mechanical one Forced coupling of the headstock carriage with the support ruler causes that when adjusting the grinding wheel and regulating wheel to a certain Center distance corresponding to a specific diameter of the workpiece at the same time a very definite value for the height adjustment of the Support ruler comes about. The said adjustment can be made according to the proposal DE 32 02 341 A1 are even made during the grinding process, when the pressure force of the grinding wheel has to be corrected. In the result is at each further approach of the regulating wheel to the grinding wheel at the same time raised the support ruler by a certain amount.

The once set, quite difficult machining position of the workpiece changes but very quickly, who the outside diameter of the workpiece when grinding decreases. This is especially the case with large changes in diameter, how they are accomplished very quickly with today's conventional CBN grinding wheels. But if the optimal operating position of the workpiece between the grinding wheel and the regulating wheel is disturbed, the grinding result is worse; It can even come about a labile position of the workpiece. In each In the case, there is a risk that the workpiece will be ground non-round. With the known Apparatus for grinding this defect can not be eliminated. Although it allows by specific adjustment by hand, a certain change in the Distance of grinding and regulating wheel in a forced coupling with the height adjustment of the support ruler. But with today's usual requirements the accuracy of grinding in mass production range the possibilities the known device no longer off.

The invention is therefore based on the object, a method for centerless To provide cylindrical grinding of the type mentioned, in which even with stronger Material removal during the entire grinding process one for an optimal Grinding result required position of the workpiece between the grinding wheel, the regulating wheel and the support ruler is guaranteed.

The solution of this task is carried out according to the claim 1.

The progress of the grinding process, on many, familiar to the expert Is to be detected by measurement or by empirical values is thus as Influence size used to determine the position of the support ruler during the grinding process adapt the changing contour of the workpiece. The correct processing position of the workpiece during the grinding process then leads to the largest possible Accuracy of the grinding result.

An advantageous embodiment of the method according to the invention can therein exist that during the grinding process, the contour of the workpiece metrologically detected and adjusted the support ruler in accordance with the measurement result becomes.

In this case, according to further advantageous embodiments, the diameter of the Workpiece be measured continuously or at intervals. It is also possible, during the grinding process continuously deviations of the workpiece contour to measure from the circular shape and when exceeding a certain Value of the deviation, the height adjustment and / or the inclination of the support ruler to correct this deviation. The last mentioned Possibility can with the ongoing measurement of the workpiece diameter be combined. Be used to adjust the support ruler just mentioned Factors used, this leads to a high accuracy and dimensional accuracy the finished workpieces. However, this working method is very expensive.

In mass production is often worked more economically in the way can be that the height adjustment and / or the inclination of the support ruler controlled by a fixed operating program, which is the one for a particular Workpiece type required changes, depending on from the grinding cycle and is repeated for each individual workpiece. This embodiment of the working method, the subject of a further advantageous Design is, thus takes the grinding process to each one Workpiece of a constant type in the manner of a program automatic before. With sufficiently large quantities are easily reliable reference values about the optimal adjustment of the support ruler during the grinding process obtained, so that such automatic program also to very good results leads.

Depending on the shape of the workpiece to be ground, according to a further advantageous Design also be done so that during the grinding process the workpiece with its one end face in its center of rotation supported by a stationary tip in the axial direction and around this as Swivel center is pivoted upwards. This way of working comes e.g. for valve body in question, in the known manner from a valve disk and a valve stem. Then you can in a single grinding process the valve disk and the shaft are ground.

For particularly large demands on the accuracy of the finished ground Workpieces can be provided in addition to the height adjustment and / or tilt of the support ruler and the distance between the grinding wheel and the regulating wheel automatically in the sense of an optimal operational setting will be changed. As the regulating wheel and / or the grinding wheel mostly Already stored in an adjustable headstock slide, can be this procedural measure on existing grinding machines without introduce excessive difficulties.

Finally, according to a last advantageous embodiment also provided be that the center axis of the regulating wheel inclined to the horizontal is and that the inclination angle of the central axis in accordance with the progressive Grinding process is also automatically adjusted.

The invention also relates to a device for centerless cylindrical grinding, according to claim 5.

In contrast to the prior art eliminates the difficult to estimate intervention by hand, because it is with the possibilities known today to the exact Controlling the grinding process is possible, based on stored Empirical values or calculated values precise parameters for the automatic To enter the control of the adjustment process.

Mechanically, the device can advantageously be designed in such a way be that two actuators are provided which engage the support ruler, connected to the control device and by these independently are actuated, such that during the grinding process in addition also the inclination of the support bar relative to the horizontal is specifically adjustable.

In detail, it may be advantageous to proceed in such a way that two in the vertical direction acting actuators in the longitudinal direction of the support ruler spaced at this attack.

Advantageously come as actuators adjusting spindles with CNC-controlled axes in question, each adjusting spindle is controllable for itself.

For workpieces of suitable shape, such as valve body, the Device according to the invention can be configured particularly advantageously by that it has a support with a tip, in the longitudinal direction of the support ruler arranged in front of this and on the center of rotation of the to be ground Workpiece is aligned. In such a device configured during the grinding process ensures a precise axial fixation of the workpiece, so that despite different outside diameter and also in the presence radial face or ring surfaces that are to be ground, an accurate result comes about.

In many cases, it will be sufficient for the support ruler to be a single continuous one Body is. For rotationally symmetrical bodies with different diameter ranges However, according to a particularly advantageous proposal of the above Invention an approximately over the entire length of the support ruler reaching Carrier body provided on which attack the actuators and on the two or more support bodies are arranged articulated transversely to the longitudinal direction the support body extending pivot axes in the manner of rockers with are connected to the carrier body and have different support heights. The Support ruler is so multi-part. By means of the articulated support body can a workpiece with different measurements on the outside diameters support well on the support ruler and is therefore optimal to grind.

When doing each support body on both sides of its pivot axis via compression springs is supported on the support body, can easily a self-adjusting Zero position of the carrier body can be achieved.

This embodiment can be further optimized by that between a support body and the support body located pivot axis the side of the support body and / or the support body in a vertically is mounted to the carrier body extending biased bearing. The multipart Support ruler becomes so adaptable that even workpieces with graded, different diameters can be ground. Thereby It becomes possible, entire parts families without retooling the support ruler on to grind the same grinder.

With regard to the control device of the invention is according to a further proposal characterized particularly advantageous that the support ruler a measuring device is assigned by which during the grinding process the diameter and / or deviations of the workpiece contour from the circular shape be measured, and that the measuring device with an evaluation is connected, in turn, for forwarding control signals of the control device connected is.

A simpler and particularly suitable for mass production design However, the device according to the invention can also consist in that the Control device is connected to a program unit, the control unit in accordance with a time-dependent operating program for grinding a supplies required control signals for each type of workpiece and for each individual Repeated workpiece of this type.

Fig. 1

veranschaulicht grundsätzlich den Vorgang des spitzenlosen Rundschleifens, wobei der Maschinenständer, das Stützlineal sowie die Schleif- und Regelscheibe zusammen mit dem Werkstück nur schematisch dargestellt sind.

Fig. 2

enthält eine schematische Darstellung zum Verstellen des Stützlineals mittels zweier Stellantriebe entsprechend dem Schnitt A-A in Fig. 1.

Fig. 3

hat das Schleifen eines rotationssymmetrischen Werkstücks mit unterschiedlichen Durchmesserbereichen zum Gegenstand, ebenfalls entsprechend dem Schnitt A-A in Fig. 1.

Fig. 4

ist eine Ansicht entsprechend dem Pfeil B in der Fig. 3.

Fig. 5

erläutert das Prinzip eines mehrteiligen Stützlineals entsprechend dem Schnitt A-A in der Fig. 1.

The invention will be explained in more detail with reference to exemplary embodiments, which are illustrated in the figures.

Fig. 1

basically illustrates the process of centerless cylindrical grinding, the machine stand, the support ruler and the grinding and regulating wheel are shown only schematically together with the workpiece.

Fig. 2

contains a schematic representation for adjusting the support ruler by means of two actuators corresponding to the section AA in Fig. 1st

Fig. 3

The object of the invention is the grinding of a rotationally symmetrical workpiece with different diameter ranges, likewise corresponding to the section AA in FIG. 1.

Fig. 4

is a view corresponding to the arrow B in FIG. 3rd

Fig. 5

explains the principle of a multi-part support ruler corresponding to the section AA in FIG. 1.

In Fig. 1 is the process of centreless cylindrical grinding, centerless loops called, shown schematically. Here are a grinding wheel 1 and a regulating wheel 2 arranged substantially parallel to the axis side by side. The Workpiece 3 is located on a support ruler 4, which with a wear-resistant Covering 5 is provided. The support ruler 4 is opposite to the machine stand 10 in the height adjustable, as indicated by the double arrow 6. With 7, 8 and 9 are the central axes and thus also rotational axes of the workpiece 3, the Grinding wheel 1 and the regulating wheel 2 indicated.

So that the workpiece 3 can be set in rotation, the regulating wheel 2 rotationally driven, that is, it rotates about its central axis 9. By Contact with the workpiece 3 at its outer diameter comes its rotation conditions. For grinding the workpiece surface, the grinding wheel 1 also offset in rotation about its central axis 8. The directions of rotation of Grinding wheel 1 and the regulating wheel 2 are by the curved directional arrows 11 and 12 illustrates. In the usual and known machines for Centerless cylindrical grinding are the grinding wheel 1 in a main spindle and the regulating wheel 2 is received in a regulating wheel spindle headstock. one or both headstocks can be displaced in the x direction on a common Machine stand 10 to be mounted. The x-direction is - as you know - The transverse to the longitudinal axis of the workpiece direction. Execution such headstocks and the drive of the discs are customary and therefore not shown further.

The position of the workpiece 3 on the support ruler 4 is not as clearly defined as that they could suggest schematic representation of FIG. 1. To one To achieve feed, namely the regulating wheel 2 with slightly from the horizontal tilted axis may be arranged. This also raises the workpiece slightly sloping down, which again by an inclination of the support ruler can be compensated. Thus dimensionally accurate and contoured honed Surfaces come about, the workpiece must have a very specific location between the grinding wheel 1, the regulating wheel 2 and the support bar 4 occupy. However, a situation set at the beginning of the grinding process is so exact quickly changed again when the diameter and contour of the workpiece as Change sequence of the grinding process. This is especially the case with today's conventional CBN grinding wheels the case with which a strong removal is achieved in a short time.

The remedy is that during the grinding process, the support ruler on raised and also its inclination is corrected until the optimal conditions are restored and the workpiece is ground round.

FIG. 2 therefore explains with reference to a sectional view of FIG. 1, as the Adjusting the support ruler during the grinding process is going on. The support ruler 4 with the workpiece 3 rests on two actuators 15 and 16, the in turn are supported on the machine stand 10. The actuators are in Longitudinal direction of the support bar 4 spaced from each other. In the illustrated Embodiment, the actuators by adjusting spindles with CNC-controlled Axes formed, each control spindle is controllable for itself. A Parallel displacement of the support ruler upwards can be generated by the fact that the two adjusting spindles are controlled synchronously. If in addition a tilt of the support ruler 4 by the angle α relative to the horizontal required is, the actuator 16 must be adjusted more than the actuator 15. Die Adjustment directions of the actuators are shown in Fig. 2 by the double arrows 13 and 14 marked.

Also, Fig. 3 includes a representation corresponding to the section A-A of Fig. 1. The workpiece is here a valve body 17, in the known manner consists of a shaft 18 with the valve plate 19. The valve body 17 rests Although here on a support ruler 4. On the machine frame 10 is here but In addition, a support 21 secured by screws 22, and on the support 21st a tip 20 is formed. At this point 20, the valve body 17 is supported with its front, located on the valve plate 19 end face. It can thus not occur here that the valve body 17 under the influence of the axial Grinding forces resulting from the grinding of the bevel on the valve seat, in axial direction emigrates from the grinding zone.

The central axis of the tip 20 is located at substantially the same elevation like the center axis of the grinding wheel. The axis of rotation of the valve body 17 corresponds approximately to the central axis 23 of the tip 20, as long as the support body horizontally.

These ratios are shown even better in Fig. 4, which corresponds to a view contains the arrow B in Fig. 3.

Fig. 5 illustrates a support ruler 24 in a multi-part design. It exists first from a carrier body 25, which in the manner of the support ruler shown in Fig. 2 supported by two actuators 15 and 16 on the machine frame 10 is. By different adjustment of the actuators 15 and 16 can also be achieve an inclination of the carrier body 25 here. Different, however, is that on the carrier body 25 two support body 26, 27 articulated are. These are transverse to the longitudinal axis of the support body extending pivot axes 28, 29 provided. The support body 26, 27 are characterized in the manner of Rockers connected to the carrier body 25; their pivoting mobility is illustrated by the round arrows 35 and 36. The support bodies can be different Pad heights have.

On both sides of their pivot axes are the support body 26, 27 via compression springs 30, 31 and 32, 33 supported on the carrier body 25. This turns out for possible pendulum movement of the carrier body 25, 26 in a simple manner a zero position one.

In this embodiment, the support body 26, 27 to a certain extent Adjust the dimension of workpieces where deviations of the workpiece diameter of the nominal size. During the grinding process, the Oscillating motion compensated by the process forces acting on the support body, which superimpose the spring forces.

Another advantage of the multi-part support ruler according to FIG. 5 is that that on this ruler by the pendulum movement of the support body 26, 27 Workpieces with different diameters can be ground. Thereby It is possible, entire parts families without retooling the support ruler on the same Machine to grind. Even stronger diameter differences can be be compensated by that between a support body 26, 27 and the support body 25 located pivot axis 28, 29 by adjusting by the two actuators 15,16 is brought into different height position.

Claims (11)

1. Method for centerless cylindrical grinding, for which the rotationally symmetrical workpiece (3) is located between the grinding disk (1), the regulating wheel (2) and the support guide (4) during the grinding process and for which the distance between the grinding disk (1) and the regulating wheel (2) as well as the height adjustment and/or the inclined position of the support guide (4) can automatically be varied selectively during the grinding process, characterized in that the height adjustment and/or the inclined position of the support guide (4) is controlled by a fixed operating program, which takes into consideration changes required for a particular type of workpiece and proceeds as a function of the grinding time and is repeated for each individual workpiece (3).
2. The method of claim 1, characterized in that the different inclined position of the support guide (4) is accomplished by an inclination in its longitudinal direction with respect to the horizontal.
3. The method of claim 2, characterized in that, during the grinding process, the workpiece (3) is supported in the axial direction with its one end face in its center of rotation by a stationary point (20) and is swiveled upward about this point as a center of swiveling.
4. The method of one of the preceding claims, characterized in that the central axis (9) of the regulating wheel (2) is inclined with respect to the horizontal and that the angle of inclination of the central axis (9) is likewise adjusted automatically as required by the progressing grinding process.
5. Device for centerless cylindrical grinding, with a driven grinding disk (1) and a driven regulating wheel (2), at least one of which is mounted in a headstock carriage, which can be adjusted transversely to the axial direction of the workpiece (3), and with a supporting guide (4), which supports the workpiece (3), is located between the grinding disk (1) and the regulating wheel (2) and the height of which can be adjusted by at least one actuating drive (15, 16), a control device being provided, which, during the grinding process, automatically actuates the actuating drive (15, 16) of the support guide (4) in the sense of an adjustment, which is optimum for the grinding process, especially for carrying out the method of one of the claims 1 to 4, characterized in that the control device is connected with a programming unit, which supplies control signals, required for grinding a particular type of workpiece, to the control device as required by a time-dependent operating program and repeats for each individual workpiece (3) of this type..
6. The device of claim 5, characterized in that two actuating drives (15, 16) are provided, which engage the support guide (4), are connected with the control device and can be actuated by the latter independently of one another in such a manner that, during the grinding process, the inclination of the support guide (4) with respect to the horizontal can additionally be adjusted selectively.
7. The device of claim 6, characterized by two actuating drives (15, 16), which act in the vertical direction and engage the support guide (4) at a distance from one another in the longitudinal direction of the support guide (4).
8. The device of one of the claims 5 to 7, characterized in that adjusting spindles with CNC-controlled axes are provided as actuating drives (15, 16) and that each adjusting spindle can be controlled individually.
9. The device of one of the claims 5 to 8, characterized in that it has a support (21) with a point (20), which is disposed ahead of the support guide (4) as seen in the longitudinal direction of the latter and is directed towards the center of rotation of the workpiece, which is to be ground.
10. The device of one of the claims 5 to 9, characterized in that a supporting body (25), which extends over the whole length of the support guide (24) and which is engaged by the actuating drives (15, 16), is provided and that two or more support bodies (26, 27), which are connected over swiveling axes (28, 29) extending transversely to the longitudinal direction of the supporting body (25) in the form of rockers, are hinged to the supporting body (25) and have different support heights.
11. The device of claim 10, characterized in that each support body (26, 27) is supported on the supporting body (25) by compression springs (30, 31; 32, 33) on either side of its swiveling axis (28, 29).

Images