EP1955808A1 - Grinding machine for grinding workpieces between points, grinding without points and grinding method - Google Patents

Abstract

The grinding machine grinds has a grinding wheel (1) and a controller (2) arranged independently to the work piece (3). The control (2) drives the propulsion of the work piece (3) between high parts (4) and serves to grind the peaks. An independent claim is included for a grinding method.

Description

The invention relates to a grinding machine for grinding workpieces between tips as well as for centerless grinding according to claim 1 and a grinding method for grinding a workpiece between points according to one of the claims 7, 8 or 9.

In particular, the invention relates to a grinding machine with which the advantages of grinding with tips can be combined with those of centerless grinding.

In the well-known traditional lace sharpening, the main advantage is that all the ground diameters have the same well-defined center on the workpiece axis between the tips. The disadvantage of this method is the higher cost caused by the need for centers or tips. Often the workpiece must be processed in steps, because first still a driving device must be mounted to rotate the workpiece.

In centerless cylindrical grinding, on the other hand, the workpiece is merely placed on a support between a grinding wheel and a regulating wheel. The workpiece is rotated via the drive of the regulating wheel, grinding is carried out with the likewise driven grinding wheel. Because of this construction, there is no need for tips. The advantage of this method is that it is faster and more economical, especially for large lot sizes. The disadvantage here, however, the generally quite high tooling costs and the fact that waves may not be concentric with centers or holes etc.

For example, the "KRONOS L dual" from Mikrosa, a machine available on the market, uses a technique also known as dual grinding. Dual-looping is a combination of the methods described above. The waves or parts are first ground between points. The workpiece is driven via a workpiece spindle and a workpiece entrainment. In this function, grinding between tips' thus the centricity is guaranteed. Subsequently, the workpiece is released from the tips and the centerless grinding process is performed so that the workpiece is driven by the regulating wheel and supported on each seat, whereby a stable behavior during the centerless grinding is to be achieved. This machining process should ensure that the workpiece center is not lost and the concentricity to the center is maintained. The method is particularly well-suited for producing long, slender waves, because the errors caused by the deflection can be better controlled in the final centerless grinding. The disadvantage here is that nevertheless a workpiece entrainment must be present and the conversion of the operating modes is quite expensive.

From the U.S. 3,903,655 is a grinding machine with a 'yielding' regulating wheel known. This grinding machine has a drive for a grinding wheel and a drive for a regulating wheel, wherein the drive of the grinding wheel is apparently designed for a relatively high speed. Between the grinding wheel and the regulating wheel, a workpiece is mounted on a workpiece axis between points or other suitable holding means. The drive axles of Grinding wheel and the regulating wheel and the workpiece axis are aligned in parallel. The grinding wheel, the regulating wheel and also the workpiece are mounted on separate guides, which makes it possible to adjust both the distance between the workpiece and the grinding wheel and the distance between the workpiece and the regulating wheel. The drive of the regulating wheel serves to drive the workpiece via frictional force transmission. For this purpose, the regulating wheel is made of a relatively hard but "yielding" material. Thus, the workpiece rotates here in a direction and speed determined by the regulating wheel. However, it is contemplated that the regulating wheel in this grinding machine rotates at a relatively low speed compared to the grinding wheel. This grinding machine is intended for the production of precision machine parts.

Probably in the grinding machine according to U.S. 3,903,655 The machine is not designed for a flexibility that allows both the 'grinding between tips' and the 'centerless grinding' and the guides for The grinding wheel, regulating wheel and also the workpiece are all designed for precise and defined mechanical positioning. But it is also mentioned that in principle not all three guides must be present. The disclosure does not give any details as to how a sufficient frictional force is generated between the regulating wheel and the workpiece in order to ensure that the workpiece has and also maintains the rotational speed necessary for the machining. The relevant information on the structure and the effect of the regulating wheel from a relatively hard, but "yielding" Material is merely general.

The object of the invention is to provide an improved grinding machine which combines the advantages of 'grinding between tips' with those of 'centerless grinding'. A method is also to be specified which allows greater flexibility and reliability in the manufacture of ground products.

The object is solved by the features of the device claim 1 and the method claims 7, 8 and 9.

In a grinding machine according to the invention, the drive of the regulating wheel serves both for driving the workpiece for grinding between tips and for driving the workpiece during centerless grinding. In addition, a means for measuring the contact pressure of the regulating wheel to the workpiece is present for grinding between tips.

By the drive of the workpiece for both types of grinding via the regulating wheel, can be omitted when grinding between tips otherwise necessary workpiece entrainment. In addition, by providing a means for measuring the contact pressure of the regulating wheel to the workpiece, the rotation monitoring of the workpiece is facilitated and of course can be automated.

1. a) die Regelscheibe und die Schleifscheibe besitzen unabhängige Stellantriebe und ein Werkstücksupport ist fest angeordnet;
2. b) die Schleifscheibe und ein Werkstücksupport besitzen unabhängige Stellantriebe und die Regelscheibe ist fest angeordnet;
3. c) die Regelscheibe und ein Werkstücksupport besitzen unabhängige Stellantriebe und die Schleifscheibe ist fest angeordnet.

Die jeweils gewählte Bauweise beeinflusst in der Folge natürlich auch die für die Ausführung eines Schleifvorganges zwischen Spitzen zu befolgende Verfahrensschrittfolge. Unabhängig von der gewählte Bauweise erhält man aber auch beim spitzenlose Schleifen den dort gleichermassen erwünschten Handling-Spielraum; d.h. ein dritter Stellantrieb (wie bei der US-3 903 655 ) erweist sich in keiner Betriebsart als notwendig).Furthermore, fundamentally different possibilities arise as to how the independent deliverability of grinding wheel and regulating wheel to the workpiece can be realized. The following three construction variants ac can be realized:

1. a) have the regulating wheel and the grinding wheel independent actuators and a workpiece support is fixed;
2. b) the grinding wheel and a workpiece support have independent actuators and the regulating wheel is fixed;
3. c) the regulating wheel and a workpiece support have independent actuators and the grinding wheel is fixed.

Of course, the construction chosen in each case also influences the sequence of steps to be followed for the execution of a grinding operation between points. Regardless of the chosen construction, but also in the centerless grinding there is the equally desired handling latitude; ie a third actuator (as in the U.S. 3,903,655 ) proves to be unnecessary in any operating mode).

As a means for measuring the contact pressure of the regulating wheel to the workpiece, a pressure sensor may be provided. However, the means for measuring the contact pressure of the regulating wheel on the workpiece can also include a rotation monitoring of the workpiece. If a pressure sensor is used, it can be mounted on a tailstock, on which the workpiece is mounted between points. Advantageously, when choosing a pressure sensor, for example, a known to the expert piezoelectric sensor can be used. Of course, other sensor types, such as strain gauges, can be used.

The workpiece support can advantageously also have an arrangement of tips for the simultaneous machining of a number of workpieces with successively one above the other or one behind the other and stacked pairs of tips. This allows for simultaneous Machining of several workpieces. Of course, the grinding machine in this case must be equipped with a corresponding number of grinding and regulating wheels, but the design-related overhead of the grinding machine can be kept relatively modest because still for the grinding wheel, the regulating wheel and the adjustment of the grinding wheel, the Regulator and the workpiece support no further additional drives are necessary.

Due to its basically simple construction, the grinding machine according to the invention can easily be switched over from the mode of operation of grinding workpieces between tips for centerless grinding (or vice versa). All that is required is to change the workpiece support or the workpiece holder. The former can be done for example by movability of the workpiece support in the direction of the workpiece axis, the latter, for example, by suitable additional mechanisms on the workpiece support itself. In principle, there are no dependencies on the three basic construction variants a-c of the grinding machine described above.

For the reasons mentioned above, the grinding machine according to the invention can also be used in various types of applications. Thus, the grinding machine according to the invention can be used either only for grinding between points or only for centerless grinding. But it is also possible to produce workpieces in the rough grinding with the grinding between tips, then change the operating mode of the grinding machine and then finish the workpieces finely finished with centerless grinding.

In the mode of centerless grinding the proposed machine structure also allows quite a lot of flexibility. Thus, the centerless grinding can be done either in a straight line or in a diagonal direction. The choice between these modes depends only on whether the delivery of the grinding wheel also allows a rotation of the grinding wheel about a vertical axis.

On the whole, the previously simple construction of the grinding machine achieves a versatility which has not yet been achieved.

In the following the invention will be described in more detail with reference to drawings.

Fig. 1

Eine Prinzipdarstellung zum Rundschleifen zwischen Spitzen mit einer Schleifscheibe und einer Regelscheibe,

Fig. 2

Eine Prinzipdarstellung zum gängigen spitzenlosen Rundschleifen mit einer Schleifscheibe und einer Regelscheibe,

Fig. 3

Eine weitere Prinzipdarstellung zum Rundschleifen zwischen Spitzen, mit gleichzeitigem Schleifen zweier verschiedener Durchmesser am Werkstück,

Fig. 4

Eine Prinzipdarstellung von drei Bauvarianten a bis c für eine erfindungsgemässe Schleifmaschine,

Fig. 5

Eine Prinzipdarstellung für die gleichzeitige Bearbeitung von zwei Werkstücken beim Schleifen zwischen Spitzen, und

Fig. 6

Eine Prinzipdarstellung für die gleichzeitige Bearbeitung von vier Werkstücken beim Schleifen zwischen Spitzen.

In the drawings show:

Fig. 1

A schematic diagram for cylindrical grinding between tips with a grinding wheel and a regulating wheel,

Fig. 2

A schematic representation of common centerless cylindrical grinding with a grinding wheel and a regulating wheel,

Fig. 3

Another schematic diagram for cylindrical grinding between points, with simultaneous grinding of two different diameters on the workpiece,

Fig. 4

A schematic representation of three construction variants a to c for a grinding machine according to the invention,

Fig. 5

A schematic diagram for the simultaneous machining of two workpieces when grinding between tips, and

Fig. 6

A schematic diagram for the simultaneous machining of four workpieces when grinding between tips.

The FIG. 1 shows a schematic diagram of a device for cylindrical grinding between tips with a grinding wheel 1 and a regulating wheel 2. In this case, a workpiece to be machined 3 in centers between tips 4 (see Fig. 3 ). The tips 4 define with the workpiece 1 a workpiece axis W. The tips 4 are located on a tailstock 5, which is attached to a holder 6 of a workpiece support 7. During operation, ie during a grinding process, the workpiece 3 is driven by the rotating regulating wheel 2. As already mentioned, the advantages in grinding between points, in particular in the centricity to the workpiece axis W, are for all the ground diameters on the workpiece 1.

In addition, in the form of a pressure sensor 8, a means for measuring the contact pressure of the regulating wheel 2 to the workpiece 3 is present. The pressure sensor 8 (shown only schematically here) is mounted on the tailstock 5, on which the workpiece 3 is mounted between the tips 4. The pressure sensor 8 is preferably a piezoelectric element, but other sensor types or even other means for indirect measurement of the contact pressure can also be used (cf also the comments on the grinding process below).

To a workpiece 3 in the in the FIG. 1 Of course, suitable feed means must also be present to bring the working position shown for grinding between points. For details, see FIG. 4 ,

The FIG. 2 shows a schematic diagram of an apparatus for conventional centerless cylindrical grinding with a grinding wheel 1 and a regulating wheel 2. The workpiece 3 is placed here only on a support 9, which is attached to the workpiece support 7. Driven, ie rotated, the workpiece 3 is also here through the regulating wheel 2. The workpiece 3 is ground by the likewise driven grinding wheel 1. The grinding wheel 1 and the regulating wheel 2 rotate at different speeds, wherein the rotational speed of the grinding wheel 1 is greater than the rotational speed of the regulating wheel 2, but both with the same direction of rotation. As already mentioned, the advantages of this method are in particular the higher throughput, because time-consuming clamping operations are eliminated. The centerless grinding is therefore particularly suitable for the production of large batch sizes with identically shaped workpieces.

To the device in the in the FIG. 2 Of course, suitable feed means must also be present here in order to bring the illustrated working position for centerless grinding. However, basically the same configuration of delivery means can be used as in the previously outlined loops between tips.

The FIG. 3 shows yet another schematic diagram for cylindrical grinding between tips, here with simultaneous grinding of two different diameters on the workpiece 3. In contrast to the FIG. 1 it is a view from above, otherwise reference is made to the statements there.

The FIG. 4 now shows a schematic diagram of three construction variants a to c for a grinding machine according to the invention. With all three construction variants, the grinding wheel 1 and the regulating wheel 2 can be delivered to the workpiece independently of each other. In all three of the following brief descriptions of the method steps, it is assumed that in a starting position, the grinding wheel 1, the workpiece 3 and the regulating wheel 2 do not touch each other and are spaced apart. The possibilities of movement of the respective delivery devices are indicated by the double arrows.

Construction variant a:

In the construction variant a, the regulating wheel 2 and the grinding wheel 1 independent actuators (not shown) and the workpiece support 7 is fixed.

• das Werkstück 3 auf dem Reitstock 5 zwischen den Spitzen 4 gelagert wird,
• die rotierende Regelscheibe 2 an des Werkstück 3 zugestellt wird, bis das Mittel zur Messung des Anpressdruckes der Regelscheibe 2 an das Werkstück 3 eine für den Schleifvorgang genügende Anpressdruckkraft zwischen Regelscheibe 2 und Werkstück 3 registriert, und
• anschliessend die Schleifscheibe 1 an das Werkstück 3 zugestellt wird und das Werkstück 3 zwischen den Spitzen 4 geschliffen wird.

The method for grinding a workpiece 3 between tips is done in such a way that

• the workpiece 3 is mounted on the tailstock 5 between the tips 4,
• the rotating regulating wheel 2 is delivered to the workpiece 3 until the means for measuring the contact pressure of the regulating wheel 2 on the workpiece 3 has a contact pressure force sufficient for the grinding operation registered between regulating wheel 2 and workpiece 3, and
• then the grinding wheel 1 is delivered to the workpiece 3 and the workpiece 3 is ground between the tips 4.

Construction variant b:

In the construction variant b, the grinding wheel 1 and the workpiece support 7 independent actuators (not shown) and the regulating wheel 2 is fixed.

• das Werkstück 3 auf dem Reitstock 5 zwischen den Spitzen 4 gelagert wird,
• das Werkstück 3 an die rotierende Regelscheibe 2 zugestellt wird, bis das Mittel zur Messung des Anpressdruckes der Regelscheibe an das Werkstück 3 eine für den Schleifvorgang genügende Anpressdruckkraft zwischen Regelscheibe 2 und Werkstück 3 registriert, und
• anschliessend die Schleifscheibe 1 an das Werkstück 3 zugestellt wird und das Werkstück 3 zwischen den Spitzen 4 geschliffen wird.

The method for grinding a workpiece 3 between tips is done in such a way that

• the workpiece 3 is mounted on the tailstock 5 between the tips 4,
• the workpiece 3 is delivered to the rotating regulating wheel 2 until the means for measuring the contact pressure of the regulating wheel on the workpiece 3 registers a contact pressure force between the regulating wheel 2 and the workpiece 3 sufficient for the grinding operation, and
• then the grinding wheel 1 is delivered to the workpiece 3 and the workpiece 3 is ground between the tips 4.

Construction variant c:

In the construction variant c, the regulating wheel 2 and the workpiece support 7 have independent actuators (not shown) and the grinding wheel 1 is fixed.

• das Werkstück 3 auf dem Reitstock 5 zwischen Spitzen 4 gelagert wird,
• die rotierende Regelscheibe 2 an des Werkstück 3 zugestellt wird, bis das Mittel zur Messung des Anpressdruckes der Regelscheibe an das Werkstück 3 eine für den Schleifvorgang genügende Anpressdruckkraft zwischen Regelscheibe 2 und Werkstück 3 registriert, und
• anschliessend das Werkstück 3 und die Regelscheibe 2 (gemeinsam) an die Schleifscheibe 1 zugestellt werden und das Werkstück 3 zwischen den Spitzen 4 geschliffen wird.

The method for grinding a workpiece 3 between tips is done in such a way that

• the workpiece 3 is mounted on the tailstock 5 between tips 4,
• the rotating regulating wheel 2 is delivered to the workpiece 3 until the means for measuring the contact pressure of the regulating wheel on the workpiece 3 registers a contact pressure force between the regulating wheel 2 and the workpiece 3 sufficient for the grinding operation, and
• Subsequently, the workpiece 3 and the regulating wheel 2 (jointly) are delivered to the grinding wheel 1 and the workpiece 3 is ground between the tips 4.

It should be noted that in all three described methods only a means for measuring the contact pressure of the regulating wheel is mentioned. It has already been mentioned earlier that a sufficient contact pressure of the regulating wheel on the workpiece can also be determined indirectly. Thus, instead of a pressure sensor 8, a rotation monitoring for the workpiece 3 can be provided. As soon as or as long as the workpiece 3 rotates with sufficient speed, it can be assumed that a sufficient contact pressure is present. Of course, a control or regulating device can be provided for this purpose. Only after reaching a desired setpoint speed of the workpiece 3, the grinding wheel 1 is delivered and the grinding process can begin.

Furthermore, it is also possible with all three variants of the method a-c that the workpiece 3 is ground between points 4 and finished on the support 9 with centerless grinding.

The FIGS. 5 and 6 show (in a non-scale manner) still schematic representations for the simultaneous processing of, for example, two or four workpieces 1 at Grind between points according to the FIGS. 1 . 3 and 4 , Thus, it is possible to design the workpiece support 7 with the tailstocks 5 in such a way that a number of workpieces 1 can be held and processed simultaneously adjacent to one another or one above the other and one above the other in a tailstock arrangement between tips 4. In the case of the adjacent tailstock arrangement according to Fig. 5 The grinding machine extends only in the direction of the workpiece axis W. For adjacent tailstock arrangements of this type, there is no need for further drive motors, since the respective grinding and regulating wheels 1 and 2 (not shown here for clarity) can be driven jointly and coaxially.

In the case of superimposed tailstock arrangement according to Fig. 6 Of course, the dimensioning in the height (distance between the workpiece axes W) must be adapted to the conditions and the diameter of the respective grinding and regulating wheels 1 and 2, and an equiaxial drive is no longer possible. Nevertheless, such arrangements can be very advantageous for the simultaneous production of precise workpieces in large numbers, because the production output can be multiplied with extremely compact machines. Mechanisms that allow the finish grinding of the workpieces 3 in the centerless operation on supports 9 and deliverable if necessary, can naturally complicate the construction of the tailstock assembly. These and other aids, which are necessary or may be necessary for the automatic processing or finishing of the workpieces to be produced, are not shown here for the sake of simplicity, but are in principle well known to the person skilled in the art.

In the representations according to the Figures 1-4 the drive axes of the grinding wheel 1, the regulating wheel 2 and the workpiece 3 are parallel. However, both when grinding between peaks as well as centerless grinding, the drive axis of the grinding wheel 1 does not necessarily have to run parallel to the workpiece axis W. If the feed device for the grinding wheel is additionally provided with a device for tilting the grinding wheel axis, it is possible to work with both a straight line engraving method and a beveling method. The latter allows the grinding of shoulders on the workpiece.

In the FIGS. 5 and 6 not shown, the person skilled in principle known as a constructive measure, but also the possibility to provide on the holder 6, a device with which a (not shown here) height-adjustable support 9 can be inserted for the centerless cylindrical grinding on which the workpiece. 3 in case of release by the tips 4 can be supported for further centerless grinding. Such a support 9 could then, for example, a shape as in the schematic drawing according to Fig. 2 shown have. With devices of this type, therefore, a grinding machine designed according to the invention could even be used for a partially or fully automated change of grinding processes by means of grinding between tips to grinding operations by means of centerless grinding.

List of reference numerals:

1

grinding wheel

2

Regulating wheel

3

workpiece

4

sharpen

5

tailstock

6

bracket

7

Workpiece support

8th

pressure sensor

9

edition

W

Workpiece axis

Claims (11)

Grinding machine for grinding workpieces (3) between points as well as for centerless grinding, with a drive for a grinding wheel (1) and a drive for a regulating wheel (2), wherein the workpiece (3) between the grinding wheel (1) and the regulating wheel (2) can be stored either between tips (4) on a workpiece axis (W) or on a support (9) for centerless grinding, and wherein - At least the drive axes of the regulating wheel (2) and the workpiece axis (W) are aligned in parallel and - The grinding wheel (1) and the regulating wheel (2) are independently deliverable to the workpiece (3), characterized in that the drive of the regulating wheel (2) for driving the workpiece (3) during grinding between tips (4) or for driving the workpiece (3) is used for centerless grinding and wherein for grinding between tips (4) means for measuring the contact pressure of the regulating wheel is present on the workpiece. Grinding machine according to claim 1, characterized in that the grinding wheel (1) and the regulating wheel (2) are independently deliverable to the workpiece (3) by one of the following three construction variants a, b or c is realized: a) the regulating wheel (2) and the grinding wheel (1) have independent actuators and a workpiece support (7) is fixed; b) the grinding wheel (1) and a workpiece support (7) have independent actuators and the Regulator (2) is fixed; c) the regulating wheel (2) and a workpiece support (7) have independent actuators and the grinding wheel (1) is fixed; Grinding machine according to claim 1 or 2, characterized in that the means for measuring the contact pressure of the regulating wheel (2) on the workpiece (3) is a pressure sensor (8). Grinding machine according to claim 1 or 2, characterized in that the means for measuring the contact pressure of the regulating wheel (2) to the workpiece (3) includes a rotation monitoring of the workpiece. Grinding machine according to claim 3, characterized in that the pressure sensor (8) on a tailstock (5) is mounted, on which between the tips (4) the workpiece (3) is mounted. Grinding machine according to one of the claims 2 to 5, characterized in that the workpiece support (7) has an array of tips for simultaneously processing a number of workpieces with one behind the other or one above the other or one behind the other and stacked pairs of tips. A method for grinding a workpiece between points (4) with a grinding machine according to claim 2, wherein the construction variant a) is realized, characterized in that - The workpiece (3) on the tailstock (5) between the tips (4) is stored, - The rotating regulating wheel (2) is delivered to the workpiece (3) until the means for measuring the contact pressure of the regulating wheel to the workpiece registered for the grinding process contact pressure between regulating wheel (2) and workpiece (3), and - Which then the grinding wheel (1) is delivered to the workpiece (3) and the workpiece (3) between the tips (4) is ground. Method for grinding a workpiece (3) between points (4) with a grinding machine according to claim 2, wherein the construction variant b) is realized, characterized in that - The workpiece (3) on the tailstock (5) between the tips (4) is stored, - The workpiece (3) is delivered to the rotating regulating wheel (2) until the means for measuring the contact pressure of the regulating wheel to the workpiece registered for the grinding process contact pressure between regulating wheel (2) and workpiece (3), and - Which then the grinding wheel (1) is delivered to the workpiece (3) and the workpiece (3) between the tips (4) is ground. Method for grinding a workpiece (3) between points (4) with a grinding machine according to claim 2, wherein the construction variant c) is realized, characterized in that - The workpiece (3) on the tailstock (5) between the tips (4) is stored, - The rotating regulating wheel (2) is delivered to the workpiece (3) until the means for measuring the Contact pressure of the regulating wheel to the workpiece registered for the grinding process contact pressure between the regulating wheel (2) and the workpiece (3), and - Then the workpiece (3) and the regulating wheel (2) are delivered to the grinding wheel (1) and the workpiece (3) between the tips (4) is ground. Method for grinding a workpiece according to one of the claims 7, 8 or 9, characterized in that the workpiece (3) is ground between points (4) and then finished on the support (9) with centerless grinding. A method for centerless grinding a workpiece with a grinding machine according to claim 1 or 2, wherein - The workpiece (3) is placed on the support (9) for the centerless grinding, and - The workpiece (3) is then ground in a centerless grinding process, either in a straight line or in a Schrägeinstichverfahren.

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