DE102021129551A1 - Eccentrically adjustable tool chuck - Google Patents

Abstract

An eccentrically adjustable tool chuck is specified, with a housing (12) which has a connection (16) for the rotary drive and defines an axis of rotation (17); with a shaft (20) which is rotatably mounted in the housing (12), an axis of rotation of the shaft (20) being offset eccentrically with respect to the axis of rotation (17) of the housing (12); with a tool holder (26) in the shaft (20) for receiving a tool (18), which is offset eccentrically with respect to the axis of rotation of the shaft (20); with a fixing device (27) for fixing the tool (18) in a predetermined position secured against rotation within the tool holder (26); and an adjustment device (36) for angularly adjusting the shaft (20) relative to the housing (12).

Description

The invention relates to an eccentrically adjustable tool chuck, in which the tool holder can be adjusted between a centrally aligned position, which is suitable for example for drilling, and between an eccentrically offset position, which is suitable for example for turning or deburring.

From the DE 10 2015 013 247 A1 a drill with a counter-drilling function and a drilling method for lightweight materials are known, with which on the one hand a drilling process can be carried out in a centrally aligned position of the drill and on the other hand with an eccentrically offset arranged position with a particularly laterally ground cutting edge in the opposite direction of rotation drilling to the finished dimension takes place.

Such drills are used in particular in lightweight construction, in order to avoid fraying of the bore during production in the case of multilayer materials which contain, for example, a titanium layer and a carbon fiber layer. For example, in aircraft construction, numerous such holes have to be made in multi-layer materials. In the known drill mentioned above, switching between a centrally aligned drilling operation and an eccentrically offset operation takes place by reversing the direction of rotation by means of a corresponding drill chuck.

The reversal of the direction of rotation has proven to be particularly disadvantageous, since this means that sufficient chip removal is no longer guaranteed when the direction of rotation is reversed. Because the chips are no longer conveyed outwards, as in normal operation, but run into the workpiece. This leads to only a very limited punching time of the drill. In addition, with the eccentric offset of the drilling tool, there is no longer any balancing, which is why the range of use is limited to a maximum of around 4000 rpm.

From the EP 0 075 061 A1 Another drill with a deburring option and a drill chuck are known, with which an adjustment between a centered position for drilling and an off-center position for deburring is made possible. For adjustment between the two positions, the drill chuck has an outer sleeve in which an inner sleeve is held, with the two sleeves being coupled to one another in a rotationally fixed manner via a transverse pin. A contact means is used for switching, by means of which a movement between the two positions and latching takes place.

Such a drill chuck has a relatively complicated structure and has an imbalance, which is why the field of application is very limited.

From the EP 0 103 291 A1 Another drill chuck is known that allows a drill tool to be adjusted between a centered and an off-center position. Here, a clamping unit for receiving the drilling tool is pivotably coupled to a drive shaft. The clamping unit includes a clamping cone with a spherical peripheral surface, which is held in an inner cylindrical surface of a cup-shaped area of a drive element. A displacement movement between the two positions is generated by means of a pneumatic piston-cylinder unit.

This drill chuck is also constructed in a relatively complicated manner and has an imbalance, which is why the field of application is very limited.

Against this background, the invention is based on the object of creating a simply and reliably constructed, eccentrically adjustable tool chuck with which an adjustment of the tool holder between a centrally aligned position and an eccentrically offset position is possible without reversing the direction of rotation.

• - einem Gehäuse, welches einen Anschluss zum Drehantrieb aufweist und eine Drehachse definiert;
• - einer Welle, die im Gehäuse drehbar gelagert ist, wobei eine Drehachse der Welle gegenüber der Drehachse des Gehäuses außermittig versetzt angeordnet ist;
• - einer Werkzeugaufnahme in der Welle zur Aufnahme eines Werkzeuges, die gegenüber der Drehachse der Welle außermittig versetzt angeordnet ist;
• - einer Fixiereinrichtung zur Festlegung des Werkzeugs in einer vorbestimmten, gegen Verdrehen gesicherten Lage innerhalb der Werkzeugaufnahme; und
• - einer Stelleinrichtung zur winkelmäßigen Verstellung der Welle relativ zum Gehäuse.

According to the invention, this object is achieved by an eccentrically adjustable tool chuck with:

• - A housing which has a connection to the rotary drive and defines an axis of rotation;
• - A shaft which is rotatably mounted in the housing, with an axis of rotation of the shaft being offset eccentrically with respect to the axis of rotation of the housing;
• - A tool holder in the shaft for receiving a tool, which is arranged eccentrically offset relative to the axis of rotation of the shaft;
• - A fixing device for fixing the tool in a predetermined position secured against rotation within the tool holder; and
• - An adjusting device for the angular displacement of the shaft relative to the housing.

The invention is completely solved in this way.

Due to the eccentric arrangement of the shaft, which is rotatably mounted in the housing, in combination with the tool holder in the shaft, which is offset eccentrically in relation to the axis of rotation of the shaft is arranged, can be adjusted by an angular adjustment of the shaft relative to the housing, the tool holder without a reversal of direction of rotation between a centrally aligned position and an eccentrically offset position.

Such an arrangement allows for a simple and reliable construction while at the same time allowing high speed rotation in the centered position since the chuck can be balanced in this position.

According to a further embodiment of the invention, the shaft is angularly between a first position, in which the tool holder is centrally aligned with the axis of rotation of the housing, and a second position, in which the tool holder is arranged eccentrically offset with respect to the axis of rotation of the housing, preferably between two stops adjustable.

Through the use of two stops, a position of the tool holder aligned centrally to the axis of rotation of the housing can be reliably ensured and a precise offset to the axis of rotation of the housing can also be ensured by the stop at the other end.

According to a further embodiment of the invention, the tool chuck is balanced in the first position with respect to the axis of rotation of the housing.

This is first ensured mathematically by a corresponding weight distribution of the masses within the tool chuck. In addition, in the centrally aligned position, a balancing treatment is preferably carried out on a balancing machine in order to ensure balanced operation even at high speeds. For this purpose, bores are preferably made in the housing at suitable points in order to achieve a balanced run.

In this way, all parts of the tool chuck, including the part of a tool held in the tool holder, can be balanced. Only the part of a tool outside the tool holder cannot be included in the balancing process.

In this way, operation in the first, centered position is possible up to high speeds, for example in the range of up to 12,000 rpm or more.

According to a further embodiment of the invention, the fixing device comprises a pin which bears against an associated surface of the tool, for example a Weldon surface, and is preferably braced by means of a screw.

This ensures that the tool is securely fixed in a predetermined position within the tool holder.

According to a further embodiment of the invention, the stops are formed by two screws held in the housing, which interact with a groove on the shaft.

This is a simple and effective way of limiting the angle of rotation of the shaft and thus adjusting the eccentric displacement.

According to a further embodiment of the invention, the adjusting device has a link guide, which converts an axial movement of a drive device into a rotary movement of the shaft.

In this way, a simple and reliable angular adjustment of the shaft is guaranteed.

According to a further embodiment of the invention, the drive device can be driven by means of a fluid pressure.

In this case, the drive device preferably has a piston which can be moved in the axial direction against a prestressing force.

According to a further embodiment of the invention, the piston is guided in an axially movable manner within a cavity of the housing and is axially prestressed by a plurality of spring elements.

In this case, a fluid under pressure can preferably be fed into the cavity formed between the piston and the housing for the axial movement of the piston.

In this way, a simple and reliable adjustment of the tool chuck between the first position aligned with the axis of rotation of the housing and the second eccentrically offset position is made possible.

According to a further embodiment of the invention, a fluid connection for a minimum quantity lubrication leading to the tool holder is provided, which can be coupled to the cavity via a first valve.

In this way, a minimum quantity lubrication that is already provided on the tool chuck can be used to switch over the tool chuck between the first and second position.

For this purpose, the first valve preferably has a predetermined opening pressure for activation, which is dimensioned such that an axial movement of the piston occurs against the prestressing force of the spring elements when the opening pressure is reached.

This measure has the advantage that in the event of a pressure failure, the piston is automatically returned to its starting position by the prestressing force of the spring elements, so that the tool holder is in the first, centrally aligned position.

According to a further embodiment of the invention, the first valve is designed, when activated, to interrupt the fluid supply for the channel leading to the tool holder for minimum quantity lubrication and to apply the fluid pressure to the cavity for axial movement of the piston.

In this way, a suitable increase in pressure enables the tool chuck to be switched between the first and second position on the one hand and, on the other hand, when the first valve is activated by a high pressure, a fluid supply for the channel leading to the tool holder is interrupted, so that there is no adverse effect on the minimum quantity lubrication.

According to a further embodiment of the invention, a second valve is provided which is designed to open below the predetermined opening pressure for the first valve in order to vent the cavity to the outside.

This ensures that as long as the predetermined opening pressure for activating the first valve is not applied, the piston cannot move against the biasing force of the spring elements, so that a stable position in the first, centrally aligned position is ensured.

According to a further embodiment of the invention, a third valve is provided, which is designed to vent the cavity between the housing and the piston to the outside if the fluid pressure fails.

In this way, in the event of a pressure failure, it is ensured that there is no adjustment to the second, eccentrically offset position.

According to a further embodiment of the invention, the tool holder is designed as a bore at the outer end of the shaft.

This enables a tool to be easily accommodated, in particular in the form of a drilling tool.

It goes without saying that the features of the invention mentioned above and those yet to be explained below can be used not only in the respectively specified combination but also on their own or in other combinations without departing from the scope of the invention.

• 1 eine perspektivische Darstellung eines erfindungsgemäßen Werkzeugfutters;
• 2 eine Längsansicht des Werkzeugfutters gemäß 1;
• 3 einen Schnitt durch das Werkzeugfutter gemäß 2 längs der Linie III-III in vergrößerter Darstellung;
• 4 einen Schnitt durch das Werkzeugfutter gemäß 2 längs der Linie IV-IV;
• 5 eine perspektivische, quer geschnittene Darstellung des Werkzeugfutters gemäß 4;
• 6 einen Schnitt durch das Werkzeugfutter gemäß 4 längs der Linie VI-VI in vergrößerter Darstellung;
• 7 eine perspektivische Darstellung des Werkzeugfutters gemäß 1, jedoch ohne das Gehäuse;
• 8 eine perspektivische Ansicht des Werkzeugfutters gemäß 1, jedoch ohne das Gehäuse, gesehen von der Unterseite; und
• 9 eine perspektivische Ansicht des Werkzeugfutters gemäß 7, ohne das Gehäuse, in einer gegenüber 8 leicht abgewandelten Position.

Further features and advantages of the invention result from the following description of a preferred exemplary embodiment with reference to the drawing. Show it.

• 1 a perspective view of a tool chuck according to the invention;
• 2 a longitudinal view of the tool chuck according to FIG 1 ;
• 3 according to a section through the tool chuck 2 along the line III-III in an enlarged view;
• 4 according to a section through the tool chuck 2 along line IV-IV;
• 5 a perspective, cross-sectional view of the tool chuck according to 4 ;
• 6 according to a section through the tool chuck 4 along the line VI-VI in an enlarged view;
• 7 according to a perspective view of the tool chuck 1 , but without the case;
• 8th a perspective view of the tool chuck according to FIG 1 , but without the case, seen from below; and
• 9 a perspective view of the tool chuck according to FIG 7 , without the housing, in a opposite 8th slightly modified position.

A tool chuck according to the invention is in the 1 until 9 shown and denoted overall by the number 10.

The tool chuck 10 has according to 1 a hollow-cylindrical housing 12 which is closed off at its first end by a closing flange 14 and at this end has a connection 16 for rotary drive by a machine tool, for example in the form of an HSK connection. At the opposite second end, the housing 12 is bounded by a ring 22 of reduced diameter completed, in front of it sits a union nut 24, which is screwed to a slightly protruding shaft 20 to the outside. A tool 18 in the form of a drill can be seen projecting outwards from the shaft 20 .

The tool chuck 10 or the housing 12 can be driven in rotation about an axis of rotation 17 by means of the connection 16 .

According to 3 a shaft 20 is rotatably mounted within the housing 12, which has an axis of rotation which is offset eccentrically relative to the axis of rotation 17 of the housing 12, so that a certain eccentricity results.

A tool holder 26 in the form of a bore is provided within the shaft 20 at the second, outer end, in which a tool 18 can be accommodated. The tool 18 can be fixed in a predetermined rotational position within the tool holder 26, for which purpose a fixing device is provided, which is denoted by 27 in its entirety.

For this purpose, the tool 18 has a flat surface 28 in the area of its tool shank, which can be a so-called Weldon mount. An associated pin 29 is pressed against the flat surface 28 by means of a screw 30 so that the tool 18 is in a defined position within the tool holder 26 or the shaft 20 .

The shaft 20 is angularly adjustable by means of an adjusting device, which is generally designated 36, between a first position in which the tool holder 26 is aligned centrally with the axis of rotation 17 of the housing and a second position in which the tool holder 26 is opposite the axis of rotation 17 of the housing 12 is arranged offset eccentrically. The adjustment angle required for this can be approximately 30°, for example.

The first position and the second position are each limited by stops. For this, as in the 3 until 5 As can be seen, a first screw 32 is received on one side of the housing 12, the end of which engages in a corresponding groove provided in the surface of the shaft 20. The groove 33 extends over a certain angular range and has a first end 56 and a second end 57 .

A second screw 34 is accommodated on the opposite side of the housing 12 , the end of which in turn engages in an associated annular circumferential groove 35 on the shaft 20 . This second groove 35 has a first end 58 and a second end 59 .

How out 4 As can be seen, it is thus possible to adjust the shaft 20 between the first position shown in the figures, in which the tool holder 26 is centrally aligned with the axis of rotation 17 of the housing 12, and the second position, in which there is an eccentric offset of the Tool holder 26 relative to the axis of rotation 17 of the housing 12 results. Here, the first position is limited by a stop of the second screw 34 at the first end 58 of the associated groove 35 . Furthermore, the second position is limited by a stop of the first screw 32 at the second end 57 of the first groove 33 .

To adjust the shaft 20 between the first position and the second position, an adjusting device denoted overall by 36 according to FIG 3 . The actuating device 36 has a drive device 37, by means of which a piston 38, which is accommodated in an axially displaceable manner within a cavity 40 of the housing 12, can be displaced along an inner surface 41 of the cavity 40 by means of fluid pressure. The piston 38 is a total of five spring elements 42, which are each constructed identically and their arrangement in particular from the 4 and 5 can be seen, biased towards the first position, so that the piston 38 under the action of the spring force according to 3 moves to the right and rests against an inner flange 49.

An axial movement of the piston 38 within the cavity 40, which is generated by fluid pressure, leads to a rotation of the shaft 20 relative to the housing 12. The link guide has a screw 54 which is held in the shaft 20 and engages in an associated, inclined guide groove 53 of the piston 38 . If the piston 38 thus moves against the action of the spring elements 42 from the in 3 shown position to the left, this leads to a rotary movement of the shaft 20 relative to the housing 12.

In order to move the shaft 20 between the first position and the second position, the drive device 37 is provided, which enables the piston 38 to be moved by means of fluid pressure against the biasing force of the spring elements 42 .

A minimum quantity lubrication MMS provided on the tool chuck 10 is used for this purpose. A central fluid connection 44 for the MQL is connected to the cavity 40 via a first valve 46 and an associated channel 55 . A connecting channel 51 leads from the fluid connection 44 via the first valve 46 to a central lubricant channel 50 for MQL, which leads to the tool holder 26 . The ends of the central Lubricant channel 50 and the connecting channel 51 are each closed by associated plugs 48 and 47, respectively.

in the in 3 The position shown can the compressed air, via which the MQL is fed, thus reach the first valve 46 in the central lubricant channel 50. In normal operation, the MQL is operated with an air pressure of around 2 bar, for example. If the pressure within the MQL is now increased to a predetermined operating pressure so that the force of the spring elements 42 can be overcome, e.g. to a pressure of 5 bar, the first valve 46 switches through and enables the fluid pressure to overflow via the connecting channel 55 into the cavity 40, while at the same time the connection to the central lubricant channel 50 via the connecting channel 51 is closed.

The pressure within the cavity 40 thus leads to a movement of the piston 38 against the prestressing force of the spring elements 42 and, as a result of the link guide 52, leads to a rotation of the shaft 20 relative to the housing 12. The piston 38 itself is held in the housing 12 by means of a screw 64 , which engages in an axially extending groove 66 on the piston 38, secured against rotation.

So that no force is exerted on the cylinder 38 below the predetermined pressure for activation, which leads to the rotation of the shaft 20, an associated second valve 60, which is in 6 is recognizable, designed to bring about a venting of the cavity 40 to the connection 44 for the MQL down to just below the opening pressure of the first valve 46 .

A third valve 62, also in 6 is recognizable, is intended to vent the channel 50 leading to the tool holder 26 to the outside in the event of a pressure failure of the fluid for the MQL.

The housing 12 is sealed towards the outside on the tool side, for which purpose a seal 23 is provided which is held by a ring 22 which is screwed onto the shaft 20 . In addition, a union nut 24 screwed onto the outside of the shaft 20 serves to secure the ring 22.

The tool chuck 10 is balanced in the first position, in which the tool holder 26 is aligned centrally with the axis of rotation 17 of the housing 12, for which purpose the mass distribution within the tool chuck 10 is adjusted by means of suitable bores or projections such that a balanced state results. Before the tool chuck is put into operation, it is preferably additionally finely balanced on a balancing machine in order to ensure balanced operation even at high speeds.

As a result of the special design of the drive device 37, a loss of fluid pressure causes the piston 38 to move into its right starting position under the action of the spring elements 42, so that the first, centrally aligned position of the tool holder 26 results.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102015013247 A1 [0002]
• EP 0075061 A1 [0005]
• EP 0103291 A1 [0007]

Claims (16)

Eccentrically adjustable tool chuck, with: - A housing (12) which has a connection (16) for rotary drive and defines an axis of rotation (17); - A shaft (20) which is rotatably mounted in the housing (12), an axis of rotation of the shaft (20) being offset eccentrically relative to the axis of rotation (17) of the housing (12); - A tool holder (26) in the shaft (20) for receiving a tool (18) which is offset eccentrically relative to the axis of rotation of the shaft (20); - A fixing device (27) for fixing the tool (18) in a predetermined position secured against rotation within the tool holder (26); and - An adjusting device (36) for the angular adjustment of the shaft (20) relative to the housing (12). tool chuck after claim 1 wherein the shaft (20) is angularly positioned between a first position in which the tool holder (26) is centered with the axis of rotation (17) of the housing (12) and a second position in which the tool holder (26) is opposite the Axis of rotation (17) of the housing (12) is arranged eccentrically offset, preferably between two stops (57, 58) is adjustable. tool chuck after claim 2 , which is balanced in the first position with respect to the axis of rotation (17) of the housing (12). Tool chuck according to one of the preceding claims, in which the fixing device (27) comprises a pin (29) which bears against an associated surface (28) of the tool (18), preferably braced by means of a screw (30). Tool chuck according to one of claims 2 until 4 , in which the stops are formed by two screws (32, 34) held in the housing (12) and cooperating with a groove (33, 35) on the shaft (20). Tool chuck according to one of the preceding claims, in which the adjusting device (36) has a link guide (52) which converts an axial movement of a drive device (37) into a rotary movement of the shaft (20). tool chuck after claim 6 , wherein the drive device (37) can be driven by means of a fluid pressure. tool chuck after claim 6 or 7 , In which the drive device (37) has a piston (38) which is movable in the axial direction against a biasing force. tool chuck after claim 8 In which the piston (38) is guided in an axially movable manner within a cavity (40) of the housing (12) and is axially prestressed by a plurality of spring elements (42). tool chuck after claim 9 , in which, for the axial movement of the piston (38), a fluid under pressure can be fed into the cavity (40) formed between the piston (38) and the housing (12). tool chuck after claim 10 In which a fluid connection (44) is provided for a tool holder (26) leading to minimum quantity lubrication (50) which can be coupled to the cavity (40) via a first valve (46). tool chuck after claim 11 , in which the first valve (46) has a predetermined opening pressure for activation, which is dimensioned such that an axial movement of the piston (38) against the biasing force of the spring elements (42) results when the opening pressure is reached. tool chuck after claim 12 , in which the first valve (46) is designed, when activated, to interrupt the fluid supply for the channel (50) leading to the tool holder (26) for minimum quantity lubrication and to close the cavity (40) for the axial movement of the piston (38) with the fluid pressure pressurize Tool chuck according to one of Claims 11 until 13 , in which a second valve (60) is provided, which is designed to open below the predetermined opening pressure for the first valve (46) in order to vent the cavity (40) to the outside. tool chuck after Claim 14 , in which a third valve (62) is provided, which is designed to vent the cavity (40) between the housing (12) and the piston (38) to the outside if the fluid pressure fails. Tool chuck according to one of the preceding claims, in which the tool holder (26) is designed as a bore at the outer end of the shaft (20).

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