EP2394783B1 - Rotary grinding machine without points and method for grinding without points with height-adjustable control wheel - Google Patents

Description

The invention relates to the technical field of production technology and in particular to a centerless grinding machine according to claim 1 and a corresponding method according to claim 16.

Centerless cylindrical grinding usually involves sanding above or below the centers of the grinding and regulating wheel. The tangent angle at which the workpiece abuts the grinding and regulating wheel is typically between 6 and 11 degrees.

To achieve this, the workpiece support is adjusted in height. This happens, for example, via a wedge, an eccentric shaft or via a motor-adjustable axle.

In addition, the diamond for dressing the regulating wheel in the center height, i. be brought to the height of the axis of rotation of the workpiece to obtain a straight surface line at the contact height of the workpiece with the regulating wheel. For this purpose, the diamond height of the regulating wheel must first be designed adjustable. However, an exact adjustment is still difficult because the dressing must be carried out offset to the circumference.

When working in the oblique engraving method, where the axis of rotation of the grinding wheel is not parallel to the workpiece support and the axis of rotation of the regulating wheel, the support must be tilted to avoid distortion to avoid or minimize a shoulder of the workpiece.

Regardless of the grinding stitch, adjusting the support height is always tedious. In addition, different heights must be tested in advance to achieve optimum roundness. In addition, the height must be readjusted when the grinding wheel wears. However, since the space between grinding and regulating wheel only offers limited space, height adjustment systems can not be made as solid as would be necessary for supporting a workpiece. When grinding outside the center height of the grinding wheel, profile distortions therefore occur on the shoulders during oblique engraving.

Documents JP2003-191153 and US4570387 show grinding machines and methods according to the preamble of claims 1 and 16.

It is an object of the present invention to overcome these disadvantages and to provide a centerless cylindrical grinding machine, which allows easy, fast and accurate manipulation of the grinding settings, as a result reliably high-quality joints can be produced, and beyond the simple design and inexpensive to produce is.

This object is achieved by a cylindrical grinding machine according to claim 1.

In complete departure from any previously known teaching, an essential point of the cylindrical grinding machine according to the invention is that now the centers of the grinding wheel and the workpiece lie in one plane and an adjustment of the workpiece support exclusively via a - decoupled from all other movements - Height adjustment of the regulating wheel is made. The respective center of the grinding and regulating wheel as well as the workpiece is to be understood in the following to mean the point which is formed by the latter in the viewing direction of the respective axis of rotation.

This has quite a number of advantages, above all that a stable axle can be constructed for the height adjustment of the regulating wheel. As a result, the center height of the workpiece can be adjusted very accurately via the procedure of the infeed carriage of the regulating wheel. This can be used to grind always at the optimum height, especially at large Abschliff, in which the diameter of the workpiece changes. In addition, the diamond or the rotating dressing tool for the regulating wheel can be mounted at a fixed height, since the regulating wheel can be moved to the correct height. The height of its axis of rotation can come to lie both above and below the common plane. Since all settings on only one axis, namely the corresponding position of the axis of rotation of the regulating wheel are made, a particularly simple construction of the machine is possible.

Preferred developments of the cylindrical grinding machine according to the invention are specified in the subclaims.

In an advantageous embodiment, it is provided that the axes of rotation of the grinding wheel and the regulating wheel are not aligned axially parallel to each other, in particular are arranged for Schrägeinstichschleifen. On the one hand, there is the need for an angular position of the axes of the workpiece profile, for example, a diagonal stitch requires. On the other hand, also from the nature of the grinding process, such as during continuous grinding with an axis that is inclined a slope forming to the other axis. In both cases, it may increasingly lead to profile distortions, which essentially result from removal of the grinding and / or regulating wheel and / or by grinding the workpiece with a consequent wandering of the workpiece from an original position. The height adjustability of the regulating wheel now makes it possible to compensate for these profile distortions by adjusting the regulating wheel alone, whereby the advantages of continuous as Schrägeinstichschleifens, such as grinding high volumes and complex workpiece profiles, are much easier to use.

In a further preferred embodiment, a motor drive for adjusting the regulating wheel is provided. Basically, of course, a manual adjustment of the regulating wheel is conceivable.

Preferably, a computing unit for automatically controlling the motor drive is also provided. A computer-controlled drive allows an already high degree of automation, e.g. by using a CNC (Computer Numeric Control) controller. This inaccuracies of a manual presetting are reliably excluded, which increases the machining quality of the workpieces.

In set-up mode, for example, different heights of the regulating wheel can be approached quickly via the CNC control in order to optimize the roundness of the workpieces. These optimal height settings of the regulating wheel are included preferably deposited on a storage unit and retrievable. Since the values are already available on the machine, a particularly fast presetting of the regulating wheel is possible. These height settings can also be stored workpiece-related, so that a quick changeover to different workpieces is possible. As a result, the processing time per workpiece decreases, which enables a rapid passage of different batches.

A particularly high degree of automation arises from the fact that the arithmetic unit is connected to the memory unit for retrieving optimum height settings of the regulating wheel. As a result, the usually required set-up time of the machine drops again considerably, since the regulating wheel can automatically retrieve the optimum height setting in each case and start in the sequence.

The arithmetic unit is further preferably designed to compensate for deviations of the axis of rotation of the workpiece from the common plane with the axis of rotation of the grinding wheel out by adjusting the regulating wheel. Such a deviation can be caused by removal of the grinding and / or regulating wheel and / or by grinding of the workpiece itself. This can be compensated by the fact that the arithmetic unit reacts to measured values of a corresponding sensor system which detects an emigration of the workpiece from its original center position. In the memory unit optimum height settings are stored for each of these deviations, which are approached by the regulating wheel.

Preferably, the arithmetic unit is also for automatically dressing the regulating wheel on at least one Dressing tool designed, which also the dressing process can be carried out automatically and thus easily, quickly and reliably. This reduces the set-up time of the machine before the actual grinding process.

It is advantageous if the at least one dressing tool is guided in the common plane of the rotation axis of the grinding wheel and the axis of rotation of the workpiece. This eliminates all adjustments in the height of the tool, which on the one hand simplifies the construction of the machine and on the other hand makes the dressing itself very simple and reliable. In addition, the tool is easily accessible for maintenance, since it is arranged to be moved out between the grinding wheel and the regulating wheel.

Another advantage arises when the at least one dressing tool can be controlled and moved in a changeable position and / or via additional axes. This facilitates the dressing of the grinding as well as the regulating wheel itself on such workpiece geometries that change greatly along the axis of rotation of the workpiece. The grinding machine is thus also quickly and reliably adjustable to workpieces that are considered to be rather difficult to grind.

It is furthermore advantageous if the at least one dressing tool has a dressing diamond or a dressing device for the grinding wheel and / or a dressing diamond or a dressing device for the regulating wheel or is prepared for the optional assembly with such dressing devices. The dressing diamond or the dressing device can be the first dressing tool for the grinding wheel and / or used as a second dressing tool for the regulating wheel.

In a further preferred embodiment, the grinding machine further includes a coolant supply, through which coolant can be brought into an engagement region of the grinding wheel with the workpiece. As a result, a reliable cooling is ensured, whereby the life of the grinding and regulating wheel is increased. Another advantage of this direct cooling is the assurance of high thermal stability. For example, an outlet nozzle of the coolant supply can be attached to a housing of the machine. Since this nozzle is permanently arranged in the grinding gap, its position must not be compensated for an operational decrease in the diameter of the grinding wheel.

The grinding wheel preferably comprises a plurality of partial grinding wheels arranged one behind the other on the axis of rotation of the grinding wheel, and the regulating wheel comprises a plurality of partial regulating wheels arranged one behind the other on the axis of rotation of the regulating wheel. Thus, several grinding operations can be performed at the same time. This reduces the time required for loading and unloading the workpiece and for loading the grinding machine.

The workpiece support is preferably designed so that the workpiece for performing sequential grinding operations along its axis of rotation is moved sequentially. For this purpose, the workpiece support in the vertical direction is designed to be rigid and movable in the horizontal direction. A total time required for the grinding operation is thereby significantly shortened. At the same time the loading the workpieces outside the grinding area, the dressing (diamond) of the grinding and regulating wheel and also an oscillation of the workpieces supported.

Preferably, the grinding machine is constructed on a machine bed of thermostable natural granite, which ensures a high mechanical and thermal stability of the components of the grinding machine.

Finally, the above object is also achieved by a method according to claim 16.

An essential point of the inventive method is that it is particularly easy to carry out. Surprisingly, namely - unlike previously thought - the grinding process can be controlled solely by a kinematically decoupled adjustment of the regulating wheel, if the centers of grinding wheel and workpiece are at a level, ie their axes of rotation form a plane. This makes a particularly efficient and effective process control possible, which can also be easily implemented in terms of design.

Preferred embodiments of the inventive method are given in the dependent claims.

As already described in connection with the cylindrical grinding machine according to the invention, it is advantageous if optimum height settings of the axis of rotation of the regulating wheel are stored and recalled. As a result, the corresponding values are quickly available, allowing a quick presetting of the regulating wheel. In addition, there are also optimal height settings for different workpieces can be stored, so that a quick change of settings for grinding different workpiece batches is feasible.

A significant simplification, acceleration and quality improvement of the grinding process is achieved by compensating for a deviation of the axis of rotation of the workpiece from the common plane with the axis of rotation of the grinding wheel by automatically adjusting the regulating wheel. For this purpose, abrasions of the grinding and / or regulating wheel and / or a grinding of the workpiece can be detected and an associated optimum height adjustment of the regulating wheel calculated or retrieved, which must be approached by the regulating wheel to compensate for the deviation of the workpiece. The abradings or the abrasion can be derived by an angle change between the center of the regulating wheel and the center of the grinding wheel on the one hand and the center of the regulating wheel and the center of the workpiece on the other hand.

If the dressing tool is guided in the common plane of the axis of rotation of the grinding wheel and the axis of rotation of the regulating wheel, eliminates errors that may be caused by a height-adjustable tool. The dressing tool can be rigidly mounted in the vertical direction. Since therefore only the regulating wheel must be adjusted to perform the dressing process, this can be carried out according to more accurate and reliable.

Figur 1

eine Prinzipskizze einer erfindungsgemässen Anordnung von Schleif-, Regelscheibe und Werkstück;

Figur 2

eine perspektivische Ansicht von schräg oben auf eine erfindungsgemässe erste Anordnung von Schleif-, Regelscheibe und Werkstück in geradem Einstich, und

Figur 3

eine perspektivische Ansicht von schräg oben auf eine erfindungsgemässe zweite Anordnung von Schleif-, Regelscheibe und Werkstück in schrägem Einstich.

In the following, exemplary embodiments of the invention with reference to the accompanying figures in detail explained. The same or equivalent parts are provided with the same reference numerals. Show it:

FIG. 1

a schematic diagram of an inventive arrangement of grinding and regulating wheel and workpiece;

FIG. 2

a perspective view obliquely from above on a first arrangement according to the invention of grinding, regulating wheel and workpiece in a straight groove, and

FIG. 3

a perspective view obliquely from above on a second arrangement of grinding, regulating wheel and workpiece according to the invention in an oblique recess.

The FIG. 1 shows a schematic diagram of the inventive arrangement of grinding wheel 10, regulating wheel 20 and workpiece 30. The workpiece 30 is located on a workpiece support 40 which is dimensioned and arranged in accordance with the dimensions of the workpiece 30 that according to the invention a center of the workpiece 30, ie its axis of rotation A-30 (Axis-30), in a common plane P (plane) with the center of the grinding wheel 10, that is, the axis of rotation A-10. For grinding the workpiece 30, the grinding wheel 10 and the regulating wheel 20 along the directions H-10 (horizontal-10) and H-20 deliver the workpiece 30 and remove it again when the grinding operation is completed. The discs 10 and 20 rotate during grinding in the specified directions R-10 and R-20. A center or rotation axis A-20 of the regulating wheel 20 has a plane P opposite to the one Height adjustment D (displacement) according to the invention, about which it has moved vertically beyond the plane P. In the figure, the axis of rotation A-20 of the regulating wheel 20 is shifted downwards relative to the plane P in the height adjustment D. However, the axis of rotation A-20 can also be adjusted by the height adjustment D upwards compared to the plane P.

The regulating wheel 20 can be moved in the directions V-20, and decoupled from the movements along the directions H-20. Thus, while the grinding wheel 10 and the workpiece 30 are invariable in height, all adjustments required for grinding are made solely via the regulating wheel 20. This includes the first start of a desired, optimal contact surface with the workpiece 30, which can be done automatically, for example via a CNC-controlled motor drive (not shown). Whose control can have a memory unit, are deposited in the optimal height settings D depending on the workpiece 30 to be grounded and retrieved by an operator. The storage unit can also record height settings D, which are dependent on a removal of the grinding wheel 10 and / or the regulating wheel 20 and / or by grinding the workpiece 30 are approached. In this case, other process variables, such as the speed and / or type of the two discs 10 and 20, flow rate of the workpiece 30, type of grinding oil, ambient temperature, etc, are taken into account. In the simplest case, a sensor system may be provided for this purpose, which detects a wandering of the workpiece 30 out of its position via an angle change between the center A-20 of the regulating wheel 20 and the center A-10 of the grinding wheel 10. The inventive arrangement is characterized by the sole height adjustment of the regulating wheel 20 structurally particularly easy to implement, especially in the area of the regulating wheel 20 sufficient space for arranging a corresponding stable vertical guidance including motor drive. In addition, all process-relevant adjustments and adjustments via the regulating wheel 20 alone feasible, which significantly simplifies the control of grinding. This control can also be used to deliver the regulating wheel 20 to a dressing tool (not shown) ideally located between the discs 10 and 20 in the plane P. In sum, therefore, the arrangement according to the invention allows for a particularly simple construction of a respective grinding machine, which moreover has a high degree of automation, with the result of significantly easier, faster and more accurate machining of the workpieces.

The FIG. 2 shows a perspective view obliquely from above on a first arrangement according to the invention of grinding wheel 10, regulating wheel 20 and workpiece 30 in a straight recess, with the same functional elements as in FIG FIG. 1 , The FIG. 2 serves in particular the representation of spatial aspects of the inventive arrangement. It can thus be seen that the workpiece 30 has different diameters. A wandering of the workpiece 30 from a desired center position can be done here only by removing the grinding wheel 10 and / or the regulating wheel 20 and / or by grinding the workpiece 30 itself. Profile distortions are not usually expected in this arrangement. By contrast, in continuous grinding, for example, the axis of rotation A-20 of the regulating wheel 20 would be slightly inclined in order to produce a slope along which the workpiece 30 moves between the discs 10, 20. In the case of a non-optimal height adjustment of the regulating wheel 20, this would lead to profile distortions over the entire circumference of the workpiece 30. An optimal surface contact of the regulating wheel 20 to the workpiece 30 is according to the invention but now by adjusting a height adjustment D of the regulating wheel 20 on the plane P (see FIG. 1 ) along the V-20 directions. This is by sole adjustment of the regulating wheel 20 optimal roundness of the workpiece 30 to produce that was previously only laboriously and time consuming by iterative adjustment of the height of the grinding wheel 10, the height of the workpiece support 40 and the height of the regulating wheel 20 was reached.

The FIG. 3 shows a perspective view obliquely from above on a second arrangement according to the invention of grinding wheel 10 ', regulating wheel 20' and workpiece 30 'in an oblique recess. This figure is intended to clarify the spatial aspects of the inventive arrangement again. Grinding and regulating wheel 10 'and 20' are thereby the workpiece 30 'delivered at an angle between the directions H-10' and H-20 '. Such a puncture is particularly applied where in a single operation a cylindrical seat of the workpiece 30 'is to be ground together with his / her shoulder (s). In this case, a wandering of the workpiece 30 'out of its optimum grinding position, either by removal of the grinding wheel 10' and / or the regulating wheel 20 'and / or by grinding on the workpiece 30' itself lead to profile distortions at the shoulders. To profile distortions leads mainly the exit of the Grinding wheel 10 ', which leads to a further erosion at the center height after the grinding operation.

By adjusting the height of the axis of rotation A-20 'of the regulating wheel 20' in directions V-20 'beyond a plane P', this can be avoided in a particularly simple manner. Since the axes of rotation A-10 'and A-30' of grinding wheel 10 'and workpiece 30' remain in the plane P ', a simple control of the grinding process alone on the regulating wheel 20' is possible. This makes a particularly simple type of control possible, which requires only a drive for height adjustment, or height adjustment of the regulating wheel 20 '. This control can provide that an optimum height adjustment D 'of the regulating wheel 20' with respect to the grinding wheel 10 'and the workpiece 30' automatically approached and even with changing diameters of the discs 10 ', 20' and / or the workpiece 30 'is adjusted , For this purpose, a sensor system may be provided, which e.g. the angle between a connection of the centers A-10 'and A-20' and / or the centers A-30 'and A-20', each to the plane P ', determined. In the figure, the axis of rotation A-20 'of the regulating wheel 20' relative to the plane P 'offset by the height adjustment D' down. Depending on the application, the axis of rotation A-20 'can also be offset upwards relative to the plane P' by the height adjustment D '. Associated values of optimum height settings D 'may be stored in a memory unit accessed by the controller to adjust the regulating wheel 20' accordingly. Even in the oblique puncture thus a highly automated, faster and high quality grinding of the workpiece 30 'is possible, and this also with a simple and inexpensive construction of a corresponding grinding machine.

Claims (19)

1. A centreless cylindrical grinder, with a grinding disc and a regulating disc (10, 20, 10', 20'), which can be positioned laterally to a workpiece (30; 30'), which can be held between the said discs (10, 20; 10', 20'), and with a workpiece support (40; 40') for depositing the workpiece (30; 30'), which is rigid in the height direction and arranged and dimensioned in such a manner that a rotational axis (A-30; A-30') of the workpiece (30; 30') and a rotational axis (A-10; A-10') of the grinding disc (10; 10') lie in a common plane (P; P'), characterised in that a height setting (D; D') of the rotational axis (A-20; A-20') of the regulating disc (20; 20'), which is kinematically decoupled from the lateral positionability thereof, can be changed beyond the plane (P; P') for positioning the regulating disc (20; 20') on the depositable workpiece (30; 30').
2. The grinder according to claim 1, in which the rotational axes (A-10, A-20; A-10', A-20') of the grinding disc and the regulating disc (10, 20; 10', 20') are not aligned axially parallel to one another, particularly for angular plunge-cut grinding.
3. The grinder according to claim 1 or 2, with a motor drive for adjusting the regulating disc (20; 20').
4. The grinder according to claim 3, with an arithmetic unit for automatically controlling the motor drive.
5. The grinder according to one of the preceding claims, with a memory unit, at which the optimum height settings (D; D') of the regulating disc (20; 20') can be stored and retrieved again.
6. The grinder according to claim 5, in which the arithmetic unit is connected to the memory unit for retrieving optimum height settings (D; D') of the regulating disc (20; 20').
7. The grinder according to one of Claims 4 to 6, in which the arithmetic unit is designed to compensate deviations of the rotational axis (A-30; A30') of the workpiece (30; 30') from the common plane (P; P') with the rotational axis (A-10; A-10') of the grinding disc (10; 10') by adjusting the regulating disc (20; 20').
8. The grinder according to one of claims 4 to 7, in which the arithmetic unit is designed for automatically dressing the regulating disc (20; 20') on at least one dressing tool.
9. The grinder according to claim 8, in which the at least one dressing tool is guided in the common plane (P; P') of the rotational axis (A-10; A-10') of the grinding disc (10; 10') and the rotational axis (A-30; A-30') of the workpiece (30; 30').
10. The grinder according to claim 8 or 9, wherein the at least one dressing tool can be controlled and moved in a changeable position and/or via additional spindles.
11. The grinder according to one of claims 8 to 10, in which the at least one dressing tool has a dressing diamond or a dresser for the grinding disc (10; 10') and/or a dressing diamond or a dresser for the regulating disc (20; 20') or is prepared for optional equipping with dressers of this type.
12. The grinder according to one of the preceding claims, furthermore with a coolant supply, by means of which coolant can be brought to an engagement region of the grinding disc (10; 10') with the workpiece (30; 30').
13. The grinder according to one of the preceding claims, wherein the grinding disc (10; 10') comprises a plurality of partial grinding discs arranged one behind the other on the rotational axis (A-10; A-10') and the regulating disc (20; 20') comprises a plurality of partial regulating discs arranged one behind the other on the rotational axis (A-20; A-20').
14. The grinder according to claim 13, wherein the workpiece support (40) is designed to sequentially move the workpiece (30; 30') along the rotational axis (A-30; A-30') thereof to carry out sequential grinding operations.
15. The grinder according to one of the preceding claims, with a machine bed which is built from thermostable natural granite.
16. A method for the centreless grinding of a workpiece (30; 30') between a grinding disc and a regulating disc (10, 20; 10', 20'), in which the workpiece (30; 30') is arranged between the discs in such a manner that a rotational axis (A-30; A-30') of the workpiece (30; 30') comes to lie in a common plane (P; P') with a rotational axis (A-10; A-10') of the grinding disc (10; 10'), and in which the grinding disc (10; 10') and the regulating disc (20; 20') are positioned laterally to the workpiece (30; 30'), characterised in that a height setting (D; D') of the rotational axis (A-20; A-20') of the regulating disc (20; 20') can be changed beyond the plane (P; P') for positioning the regulating disc (20; 20') on the depositable workpiece (30; 30').
17. The method according to claim 16, in which optimum height settings (D; D') of the rotational axis (A-20; A-20') of the regulating disc (20; 20') are stored and retrieved again.
18. The method according to claim 16 or 17, in which a deviation of the rotational axis (A-30; A30') of the workpiece (30; 30') from the common plane (P; P') with the rotational axis (A-10; A10') of the grinding disc (10; 10') is compensated by automatically adjusting the regulating disc (20; 20').
19. The method according to one of claims 16 to 18, in which at least one dressing tool is guided in the common plane (P; P') of the rotational axis (A-10; A-10') of the grinding disc (10; 10') and the rotational axis (A-30; A-30') of the workpiece (30; 30').

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