EP1990133B1 - Grinder as tool for a processing device - Google Patents

Description

The invention relates to a grinding unit as a tool for a machining device, with a connecting means for a work spindle of the machining device and a rotation by a connection of a support member of the grinding unit with a non-rotating with the drive spindle part of the processing device.

The grinding of wood workpieces, especially the grinding and possibly profiling of the edges, carried out with this purpose edge grinding machines, which are designed for high-quality woodworking. Similarly, workpieces made of other materials, such as plastic and metal, can be machined by grinding. The use of edge grinding machines makes sense for mass production. However, there is also the need to be able to carry out sanding without having to purchase expensive special machines for this purpose, which can not be operated economically due to lower quantities and low utilization.

It is therefore known grinding units as tools for a processing device, for example in the form of a machining center or a machining robot to train roboters. Accordingly, a usually height-adjustable spindle drive of the processing device is available for the grinding unit, with which the grinding unit is connectable so that the rotational movement is transferable to a drive shaft, wherein a support member of the grinding unit against the rotation of the work spindle is rotatably connected to the machining center.

This grinding wheels are used, the working surface consists in the cylindrical surface. As far as an edge profiling is to be effected, the grinding wheels may have a corresponding negative contour of the desired profile of the edge of the workpiece. There are also known corresponding grinding wheels, which are supplemented by glued on the cylindrical surface grinding blocks, so that, for example, seven rotating grinding blocks cause edge processing and are interchangeable for a modified edge profile.

DE 43 11 534 A1 discloses a belt sander which is connectable to the work spindle of a work machine. The belt sanding unit consists of two axially parallel pulleys, around which a sanding belt is guided. With the work spindle, a drive spindle of the belt sanding unit is aligned, which is arranged in the linear center between the two pulleys. The pulleys are profiled designed to be able to grind with the sanding belt directly to the pulleys. In addition, a pressure shoe is arranged stationary between the pulleys. On the back side of the pressure shoe there is a tension roller for the sanding belt between the deflection rollers. The tension pulley is attached to a piston of a pneumatic cylinder and serves the resilient tension of the abrasive belt. In addition to grinding with the pressure shoe, the profiled arc areas of the deflection rollers, which support the sanding belt, are provided for grinding.

The known grinding units, which serve as a tool for a processing device are regularly suitable only for simple applications and do not allow high-quality grinding operations.

By DE 198 21 982 A1 is a profile belt grinding machine is known, which is equipped with a grinding head with an endless revolving around four pulleys grinding belt. The grinding head is used for the edge processing of workpieces and is deliverable in different angular positions on the edge of the workpiece. For grinding, the sanding belt is deformed with a pressure shoe according to the desired edge shape. A special feature is that around the pulleys two parallel sanding belts are guided, which can be effective with separate pressure shoes on the edge of the workpiece. A servomotor drives a drive roller with a belt drive and is located within the area bounded by the abrasive belt near the run of the abrasive belt with which the pulp machining is performed.

The invention is therefore based on the object, a grinding unit as a tool for a processing device in such a way that even grinding tasks higher quality can be done.

To solve this problem, a grinding unit according to the invention of the type mentioned is characterized in that arranged on the support member at least three guide rollers for guiding an endlessly running around a two-dimensional surface sanding belt that connectable via the connecting means to the work spindle drive unit in the center of the Abrasive belt limited area arranged and rotatably connected to at least one of the guide rollers, that at least one pressure shoe between two guide rollers for applying a pressure perpendicular to the plane of the abrasive belt is arranged and that at least one of the guide rollers for adjusting a constant belt tension is mounted resiliently adjustable.

The grinding unit according to the invention has at least three guide rollers, preferably four guide rollers, with which thus a two-dimensional surface is defined, which is bounded by the endless rotating abrasive belt. The drive unit is located between the guide rollers, in the center of the limited by the abrasive belt surface. The guide rollers are preferably arranged at an equal radial distance from the center of the surface and thus form an equilateral polygon. By dispensing with a direct drive of one of the guide rollers by the work spindle, it is possible to form a weight-balanced and compact grinding unit, which also offers significant application advantages when its support member is rotatably mounted about the axis of the work spindle, as will be explained in more detail below ,

The grinding unit according to the invention thus uses a grinding belt whose length is large by its clamping over a two-dimensional surface relative to the required area and therefore has a relatively long service life. The abrasive belt is occupied in the usual way with an abrasive grain whose grains are evenly distributed on the surface of the abrasive belt and whose grain size and optionally material of the grinding task is adjusted.

For a well reproducible grinding result, a pressure shoe between two guide rollers is provided, which exerts a pressure perpendicular to the plane of the grinding belt and thus deflects the grinding belt from the straight connection between the peripheral surfaces of the adjacent guide rollers something. In order to enable this deflection of the grinding belt, and to realize a constant belt tension, at least one of the guide rollers for adjusting a constant belt tension is adjustably mounted.

The grinding unit according to the invention thus enables the setting of the grinding parameters as in a high-quality stationary grinding machine. Only the available sanding belt length can be selected smaller than in a conventional edge sanding machine in order to achieve a well-handled sanding unit. The reduced service life due to the smaller strip length takes into account the fact that such a replaceable grinding unit is regularly required for shorter operating times.

The pressure of the pressure shoe to the sanding belt can be controlled electrically or pneumatically, with the electrical supply of tools through the machining center is provided more frequently. In a preferred embodiment of the invention, however, the grinding unit is self-sufficient, thus requires no power supply. For this purpose, the pressure shoe is preferably arranged resiliently against the grinding belt pressing. This arrangement allows several application variants. Is a long-stroke spring provided for the pressure of the pressure shoe, the delivery of the workpiece, which leads to a depression of the pressure shoe against the restoring force of its pressure spring, the effective spring force practically does not change. In this way, a constant grinding force can thus also be realized for different deflections of the grinding belt by the delivered workpiece.

If, however, a short-stroke spring is used, a different strong pressure of the workpiece against the pressure shoe to different pressure forces, so by the type of delivery of the workpiece relative to the revolving belt or relative to the pressure shoe different pressure forces - and thus different grinding intensities - can be realized.

The autarkic design of the grinding unit also contributes, if the adjusting the belt tension adjustable guide roller is resiliently arranged against the grinding belt pressing. The spring is preferably designed so that an always constant belt tension is obtained.

In a preferred embodiment of the arrangement according to the invention four guide rollers are provided, which are preferably arranged in a rectangle, in particular in a square, in a plane, so that the grinding belt limits the corresponding rectangular or square area.

It may be expedient if the grinding unit has at least one second pressure shoe which is arranged between two guide rollers, of which at least one is not identical with the guide rollers, between which the first pressure shoe is arranged. Preferably, in a quadrangular arrangement of the guide rollers, the arrangement of the pressure shoes at an angle of 90 °. Particularly expedient is the arrangement of two pressure shoes when they have different profiles and when complement the profiles of the pressure shoes to a desired profile. For a straight edge, its transition to the horizontal Surface is rounded, for example, a pressure shoe, the straight edge and the bottom rounding grind, while the other pressure shoe, the straight edge and the upper curve grinding.

The support member of the grinding unit is preferably rotatably disposed about the axis of the work spindle, even if the connection to the work spindle is already established. If the processing device is formed with a rotatable hollow tube surrounding the work spindle, which is generally called C-axis, the carrier part can be rotated by the processing device such that the second pressure shoe that may be present can be brought to the previous position of the first pressure shoe, so that the workpiece can remain in the position oriented relative to the grinding unit and is now subjected to a supplementary grinding operation by means of the second pressure shoe. Of course, it is also possible by the operation of the C-axis, in conjunction with a corresponding XY displacement of the work spindle by the processing device, a predetermined trajectory corresponding to the course of the edge of the workpiece, and thus also a non-straight edge of a Grind workpiece. The Schleibearbeitung of the workpiece can be further improved by the support member is pivotally mounted relative to the axis of the work spindle and that transmitted to the connecting means rotational movement of the work spindle via a pivotable gearbox to a work spindle of the drive unit is transferable. The transmission of the rotational movement to a standing by the pivoting movement at an angle to the work spindle axis can be done by any suitable homokinetic gear, but also with a flexible shaft or via a suitable bevel gear with larger swivel angles. The support member may preferably be provided with a controllable pivot drive, so as to allow different feed angles to the edge. In an advantageous embodiment, the carrier part can be fixed in its pivoted position, in particular by a clamping device.
The support member is preferably a support platform on which the guide rollers and the drive unit are mounted. The transmission of the rotary motion transmitted to the drive unit to at least one guide roller preferably takes place with a flexible means, for example in the form of a chain or a drive belt. In particular, the possible slip in a non-profiled drive belt slip These are prevented by the use of a toothed belt as a drive belt.

Figur 1

einen Hochschnitt durch ein erstes Ausführungsbeispiel eines erfindungsgemäßen Schleifaggregats, das in eine Arbeitsspindel eines Bearbeitungszentrums eingesetzt ist;

Figur 2

eine schematische Ansicht der Unterseite des Schleifaggregats gemäß Figur 1;

Figur 3

einen schematischen Querschnitt durch ein zu schleifendes Werkstück und einen ersten Druckschuh sowie eines zu schleifenden Werkstücks mit einem zweiten Druckschuh;

Figur 4

eine schematische Darstellung eines zweiten Ausführungsbeispiels eines erfindungsgemäßen Schleifaggregats mit einem gegenüber der Achse der Arbeitsspindel schwenkbar ausgebildeten Trägerteil;

Figur 5

eine schematische Darstellung einer Verschwenkeinrichtung zur Festlegung der Schwenkstellung des Trägerteils;

Figur 6

eine alternative Verschwenkung des Trägerteils durch eine Verschiebung der Arbeitsspindel in Achsrichtung;

Figur 7

schematisch die Anwendung eines erfindungsgemäßen Schleifaggregats bei einem Drei-Achs-Bearbeitungskopf mit einer C-Achse;

Figur 8

die Anwendung eines erfindungsgemäßen Schleifaggregats mit einer Verschwenkmöglichkeit gemäß Figur 4 bei einem Drei-Achs-Bearbeitungskopf mit einer C-Achse;

Figur 9

eine Anwendung eines erfindungsgemäßen Schleifaggregats mit einem Fünf-Achs-Bearbeitungskopf ohne C-Achse und

Figur 10

eine schematische Darstellung der Anwendungsmöglichkeit eines erfindungsgemäßen Schleifaggregats mit einem Fünf-Achs-Bearbeitungskopf mit zusätzlicher C-Achse.

The invention will be explained in more detail below with reference to exemplary embodiments illustrated in the drawing. Show it:

FIG. 1

a high section through a first embodiment of a grinding unit according to the invention, which is inserted into a work spindle of a machining center;

FIG. 2

a schematic view of the underside of the grinding unit according to FIG. 1 ;

FIG. 3

a schematic cross section through a workpiece to be ground and a first pressure shoe and a workpiece to be ground with a second pressure shoe;

FIG. 4

a schematic representation of a second embodiment of a grinding unit according to the invention with a relative to the axis of the work spindle pivotally shaped support member;

FIG. 5

a schematic representation of a pivoting device for determining the pivotal position of the support member;

FIG. 6

an alternative pivoting of the support member by a displacement of the work spindle in the axial direction;

FIG. 7

schematically the application of a grinding unit according to the invention in a three-axis machining head with a C-axis;

FIG. 8

the application of a grinding unit according to the invention with a pivoting possibility according to FIG. 4 in a three-axis machining head with a C-axis;

FIG. 9

an application of a grinding unit according to the invention with a five-axis machining head without C-axis and

FIG. 10

a schematic representation of the application of a grinding unit according to the invention with a five-axis machining head with additional C-axis.

FIG. 1 shows in section a work spindle 1 of a machining center forming a machining center. The work spindle 1 is formed at the lower free end for receiving a connecting means 2 in the form of a conical adapter. The connecting means 2 ensures a rotationally fixed connection between the work spindle 1 and a drive shaft 3 of a drive unit 4 in the form of a belt pulley and a drive belt 5. The work spindle 1 is surrounded by a hollow cylindrical shaft 6 which is rotatable independently of the work spindle 1.

The grinding unit used in the machining center with the connecting means 2 has a support part 7 in the form of a support platform, which is connected via a cylindrical pivot bearing 8 with the hollow cylindrical axis 6, which is commonly referred to as "C-axis". For non-rotatable connection, the support part 7 has a dowel pin 9, which is inserted into a corresponding blind bore 10 in the axis 6 and thus causes the rotationally fixed connection between the axis 6 and carrier part 7. On the support member 7, a chassis plate 11 is fixed, which extends parallel to the support platform and are rotatably mounted on the four guide rollers 12, 13, 14, 15 for a revolving, endless abrasive belt 16. One of the guide rollers 12 is driven via the drive belt 5 and an associated, driven by the drive belt 5 pulley 17 and provides for the circulation of the grinding belt sixteenth

The sanding belt 16 is deflected at two places by two pressure shoes 18, 18 'from the straight line between two adjacent guide rollers 14, 15 and 12, 15, respectively, because the pressure shoes 18, 18' have the sanding belt 16 with a resilient bias relative to its circulating track Press P outward.

The view of FIG. 2 on the grinding unit from below illustrates the appropriate structure. Schematically, it is indicated that in addition to the driven guide roller 12 and the guide roller 15 with a further drive belt 5 ' can be driven. Both rollers are mounted with fixed axes of rotation. By contrast, one of the guide rollers, the guide roller 13, not stationary, but slidably mounted radially outwardly in a telescopic frame 19, as indicated by the double arrow in FIG. 2 is clarified.

For the elastic pressure of the pressure shoes 18, 18 'is in each case a compression spring 20, 20' is provided. The pressure of the guide roller 13 to the outside is also determined by a compression spring 21, the spring constant determines the belt tension for the rotating belt 16.

By a corresponding delivery of the workpiece to the grinding unit, the deflection of the pressure shoe 18, 18 ', and thus the compression of the compression spring 20 can be changed. If a long-stroke spring 20 is used, the grinding force mediated by the pressure shoe 18, 18 'remains substantially constant. In the case of a short-stroke spring 20, on the other hand, the grinding force changes, so that the contact pressure can be varied via the feed of the workpiece to the pressure shoe 18, 18 '.

FIG. 3 schematically shows a possibility of use of the two pressure shoes 18, 18 ', which over the (in FIG. 3 not shown) abrasive belt 16 act on a workpiece 22. The formed for an L-shaped, rounded profile shape 23 pressure shoe 18 provides a round cut of a vertical edge 24 with a rounded transition 25 in a horizontal surface 26 of the workpiece. After the corresponding edge is finished on the workpiece, the support member 7 is rotated with the hollow cylindrical axis 6 (C-axis) by 90 °, so now the pressure shoe 18 'reaches the previous position of the pressure shoe 18. The pressure shoe 18 'has a mirror-symmetrical profile shape 27, with which a vertical edge portion 28, and an adjoining rounded transition 29 to a horizontal underside 30 of the workpiece 22 is ground.

By applying the edge of the workpiece 22 in succession to the pressure shoe 18 and the pressure shoe 18 'thus the complete desired profile shape of the edge of the workpiece 22 is produced, since the two profile forms 23, 27 of the pressure shoes 18, 18' to the target Complement profile form.

In the FIGS. 4 to 6 a further embodiment of a grinding unit according to the invention is shown, in which the support member 7 is connected via a hinge 31 with a mounting plate 32 which is fixed by means of the dowel pin 9 rotatably on the (not shown here) axis 6. The pivot 31 is housed in a housing 33 which is supplemented by a bellows 34 which extends to the support member 7. On the support part 7, the guide rollers 12 to 15 in completely the same way as in the embodiment according to FIG. 1 attached. By pivoting the carrier part 7, the workpiece 22 can be acted upon by different angles with the grinding belt 16, so that not only an edge grinding, but also a shaping contour grinding or surface grinding can be realized. On the housing 33, an angle scale 35 is provided on which the angular adjustment of the pivoted support member 7 is read in which an angle rigidly connected to the support member 7 bolt through a circular arc slot 36 and there clamped by means of a knurled nut 37 as a clamping device in the desired angular position is.

The support member 7 may be provided on one side with a guide rod 38, at the end of a bolt member 39 is attached.

FIG. 5 illustrates that in this way an external adjustment of the pivot angle of the support member 7 is adjustable by the bolt member 39 protrudes into a laterally open, U-shaped receptacle 40 which is height adjustable on a guide carriage 41 and a guide rod 42. By adjusting the height, the tilting of the support member 7 can be set directly, such as FIG. 5 illustrated by the dashed representation.

The machining center can also be provided with a removal device for different pressure shoes 18 from a pressure shoe magazine 43. This can be taken for the respective grinding task suitable pressure shoes and used in the grinding unit. The pressure shoes 18 may have different surfaces, different material hardnesses and in particular different profile shapes.

FIG. 6 illustrates that for the defined inclination of the support member 7 is not necessarily a displacement of the U-shaped receptacle 40 is required, but in an analogous manner by an axial displacement of (in FIG. 6 not shown) work spindle can be done. By the pivoting of the support member 7 now engages the sanding belt 16 under the in FIG. 6 drawn angle φ at a vertical edge of the workpiece 22 at.

The in the FIGS. 4 to 6 shown pivoting thus allows an all-round attack of the grinding belt 16 on a workpiece 22, even if the machining center is not equipped with a five-axis machining head, but for example, only has a three-axis machining head with a C-axis 6.

FIG. 7 shows the possibility of using a grinding unit according to the invention in the connection with a three-axis machining head with a hollow cylindrical axis 6 (C-axis). The abrasive belt can only grind vertical surfaces. The rotation by means of the C-axis 6 can be ground by 90 ° to each other standing edges, since the grinding unit with the pressure shoe 18 is rotatable in a corresponding manner by 90 °.

Is according to FIG. 8 an inventive grinding head used, the analog FIG. 4 has an additional pivot axis, an oblique hiring the grinding belt 16 is made possible to the edges of a workpiece 22. The movement of the grinding head is predetermined by the three axes of movement of the processing device.

FIG. 9 illustrates the use of a grinding unit according to the invention with a five-axis machining head. In this case, no C-axis is required because the corresponding rotational movement can take place on the head itself. All possible Anstellbewegungen are performed by the spindle head itself.

According to FIG. 10 the grinding unit according to the invention is used with a five-axis machining head, which is additionally provided with a C-axis 6. hereby a full range of motion as a six-axis grinding center in all grinding directions on a 3D workpiece 22 'possible. The grinding belt 16 can not only be aligned obliquely to the workpiece, but can also be attached to the surface of the workpiece 22 'with defined grinding directions. Of course, it is also possible in this case that an additional pivot axis is provided on the grinding unit itself.

It can be seen that the grinding unit according to the invention, in conjunction with conventional processing devices, in particular machining centers, makes it possible to perform high-quality grinding tasks.

Claims (16)

1. Sanding assembly as a tool for a machining apparatus, having a connecting means (2) for a work spindle (1) of the machining apparatus and rotation prevention by way of a connection of a carrier part (7) of the sanding assembly to a part (6) of the machining apparatus that does not rotate with the work spindle (1), characterized in that at least three guide rollers (12 to 15) for guiding a sanding belt (16) that runs endlessly around a two-dimensional area are arranged on the carrier part (7), in that a drive unit (4) that is connectable to the work spindle (1) via the connecting means (2) is arranged in the centre of the area bounded by the sanding belt (16) and is connected in terms of rotation to at least one of the guide rollers (12 to 15), in that at least one pressure shoe (18, 18') is arranged between two guide rollers (14, 15; 12, 15) in order to exert a pressure perpendicularly to the plane of the sanding belt (16), and in that at least one of the guide rollers (12 to 15) is mounted in an adjustably resilient manner in order to set a constant belt tension.
2. Sanding assembly according to Claim 1, characterized in that the pressure shoe (18, 18') is arranged in a manner pressing against the sanding belt (16) in a resiliently elastic manner.
3. Sanding assembly according to Claim 1 or 2, characterized in that the guide roller (13) that is adjustable in order to set the belt tension is arranged in a manner pressing against the sanding belt (16) in a resiliently elastic manner.
4. Sanding assembly according to one of Claims 1 to 3, characterized in that four guide rollers (12 to 15) are provided.
5. Sanding assembly according to Claim 4, characterized in that the four guide rollers (12 to 15) are arranged in a rectangle.
6. Sanding assembly according to one of Claims 1 to 5, characterized in that at least one second pressure shoe (18') is arranged between two guide rollers (12, 15), at least one of which is not identical to the guide rollers (12, 14) between which the first pressure shoe (18) is arranged.
7. Sanding assembly according to Claim 6, characterized in that the pressure shoes (18, 18') have different profile shapes (23, 27).
8. Sanding assembly according to Claim 7, characterized in that the profile shapes (23, 27) of the pressure shoes (18, 18') complement one another to form a desired profile.
9. Sanding assembly according to one of Claims 1 to 8, characterized in that the carrier part (7) is arranged so as to be rotatable about the axis of the work spindle (1) in the connection to the work spindle (1).
10. Sanding assembly according to one of Claims 6 to 9, characterized in that the second pressure shoe (18') can be brought into the previous position of the first pressure shoe (18) by rotation of the carrier part (7).
11. Sanding assembly according to one of Claims 1 to 10, characterized in that the carrier part (7) is arranged so as to be pivotable in relation to the axis of the work spindle (1), and in that the rotary movement of the work spindle (1) that is transmitted to the connecting means (2) is transmissible to a drive spindle of the drive unit (4) via a pivotable gear mechanism.
12. Sanding assembly according to Claim 11, characterized in that the carrier part (7), after being pivoted, is fixable in the pivoted position.
13. Sanding assembly according to Claim 11 or 12, characterized by a controllable pivot drive for the carrier part (7).
14. Sanding assembly according to one of Claims 1 to 13, characterized in that the carrier part (7) is a supporting platform.
15. Sanding assembly according to one of Claims 1 to 14, characterized in that the drive unit (4) is provided with a flexible means for transmitting the rotation to one of the guide rollers (12, 15).
16. Sanding assembly according to Claim 15, characterized in that the flexible means is a drive belt (5, 5').

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