DE8814664U1 - Device for connecting a tool holder to a carrier, in particular a machine tool spindle - Google Patents

Description

Device for connecting a tool holder white a Carrier, especially a toolbox.

The invention relates to a device for connecting a tool holder to a carrier, in particular a machine tool spindle, with a centering bore or a centering projection arranged on the carrier concentrically to a carrier axis, with at least two clamping pieces which can be displaced in a transverse recess of the carrier which runs radially to the carrier axis, with an actuating member which is axially movable on the carrier in the direction of the carrier axis and which acts on the first ends of the clamping pieces via wedge surfaces, with a centering projection or a centering bore provided on the tool holder, which has inclined surfaces arranged at a certain angle to the carrier axis, on which the clamping pieces act with their second ends in the clamping position and thereby axially press annular surfaces which surround the centering projection or the centering bore together.

In such a known device for connecting a tool holder to a machine tool spindle (OE 35 22 555 A1), a cylindrical centering projection is provided on an attachment flange that can be connected to the machine tool spindle. The tool holder can be pushed onto the centering projection with a cylindrical centering hole. Two clamping pieces are arranged diametrically opposite one another in the centering projection, the radially outer ends of which are provided with inclined surfaces inclined at an acute angle to the carrier axis. In the clamping position, these inclined surfaces interact with the inclined surfaces provided on the tool holder in the area of the centering hole. As a result, the ring surfaces of the carrier and tool holder are pressed axially against one another with a certain clamping force when the

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Actuating member is moved in the axial direction. The size of the clamping force depends essentially on the axial force acting on the actuating member. The axial force is generated by a conventional tool clamp, which is arranged in the machine tool spindle. The

However, the axial force generated by the tool clamp cannot be increased indefinitely due to the design. It has also been shown that from a certain axial force onwards, the clamping force no longer increases linearly with the axial force, but can only be increased insignificantly. However, it is desirable to increase the clamping force, since the rigidity of the connection between the carrier and the tool holder and also the torque that can be transmitted through the connection depend on it.
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: The invention is therefore based on the object of creating a device for connecting a tool holder to a carrier, in particular a machine tool spindle, of the type mentioned at the beginning, in which, without increasing the axial force acting on the actuating member, a < significant increase in the clamping force with which the

Ring surfaces of carrier and tool holder are pressed axially together.

This is achieved according to the invention by providing a ball at the second end of each clamping piece in a

The ball socket provided for the clamping piece is recessed

and is rotatably mounted, the depth of which is slightly more than half the ball diameter, the ball diameter being dimensioned and the bevel surface being arranged opposite the ball so that in the clamped position the ball and the bevel surface touch at a force application point which is at a distance from the edge at which the bevel surface changes into an axis-parallel surface.

It has been shown that with this design of the device, a significantly higher axial clamping force can be achieved between the two ring surfaces for a given axial force acting on the actuating member. The device according to the invention therefore has the advantage that less wear occurs on the clamping parts and the inclined surfaces.

Further advantageous embodiments of the invention are characterized in the subclaims.

The invention is described in the following, with reference to the drawing

illustrated embodiments, explained in more detail. It

show: 15

Figure 1 shows a first embodiment in axial section,

Figure 2

and 3 partial axial sections of variants of the first version form,

Figure k shows an axial section of a further embodiment,

Figure 5 shows an axial section of a third embodiment.

In the drawing, 1 denotes a carrier, which is preferably a machine tool spindle. The carrier 1 can, however, also be a so-called attachment flange that can be connected to the machine tool spindle, as indicated by dash-dotted lines. The carrier may also be a turret or a part connected to the turret.

The carrier 1 usually has a centering recess 2 arranged concentrically to the carrier axis A, which in the case of the

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In the exemplary embodiment, the centering recess is cylindrical. If necessary, however, this centering recess could also be conical. The carrier 1 is also provided with two diametrically opposed transverse recesses 3. In each of the transverse recesses 3, a clamping piece U is mounted so as to be displaceable radially to the carrier axis A. The clamping pieces U preferably have a cylindrical cross-section and consequently the transverse recesses 3 are also designed as cylindrical bores. The radially inner, first end Ua of each clamping piece U is provided with a wedge surface 5 which interacts with a corresponding wedge surface 6 on the actuating member 7. The actuating member 7 is axially displaceable in the direction of the carrier axis A. It can be connected directly to the drawbar 8 of a known tool clamp arranged in the machine tool spindle 1. Instead of this direct connection, it is also possible to provide the actuating element with a pull bolt, which is then engaged by a collet connected to the drawbar of the tool clamp. 20

At the ends of the clamping piece U , a ball 9, preferably made of hard metal, is countersunk and rotatably mounted in a ball socket 10 provided in the clamping piece U. So that the ball 9 is captively connected to the clamping piece U , the depth t of the ball socket 10 is slightly more than half the diameter d of the ball 9. The area of the end Ub of the clamping piece U surrounding the ball 9 is flanged towards the ball.

The tool holder 12 usually has a centering projection 13 that fits into the centering recess 2. This centering projection 13 is hollow in the embodiment shown and has on its inside in the area of the balls 9 an inclined plane arranged at an acute angle μ to the support axis A.

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flSr.he 1U. The bevel surface 1U 1 is, up to this embodiment, part of a circumferential annular groove 15. In this embodiment, transverse grooves 16 are provided in the spindle 1 to transmit the torque, into which slot nuts 17 engage, which are connected to the tool holder 12.

In the clamping position of the clamping pieces U shown in Figure 1, the ball 9 and the inclined surface 1U touch at a point of contact, which is referred to below as the force application point P, since at this point the clamping forces are transferred from the clamping pieces U and their balls 9 to the inclined surface 1U. It is intended that the force application point P is at a distance from the edge 1Ua, at which the inclined surface 1U merges into the axially parallel surface 13a of the centering pin 13. This avoids contact and force transmission at the edge 1Ua and thus impermissible surface pressures and edge pressures at this edge 1Ua. The force transmission takes place at a distance from the edge 1Ua. By adjusting the ball diameter d and/or the corresponding arrangement of the inclined surface IU i" with respect to the ball 9, it is possible to ensure that the force application point (P) is always at the desired distance from the edge 1Ua.

It has proven advantageous if the ball diameter d is approximately 2/3 of the diameter D of the clamping piece U.

Starting from the clamping position shown in Figure 1

If, for a tool change, the drawbar 8 is moved downwards as shown in the figure, whereby the wedge 7a of the actuating member 7 comes into the position shown in dash-dotted lines, the tool holder 12 is released from the tool machine machine spindle 1 downwards, then press the

I) Inclined surface 14 on the balls 9 and thus shifts dls

. clamping pieces U radially inwards. As soon as another tool holder 12 with its centering projection 13 is inserted into the centering hole 12, the drawbar &thetas; is again 'r 5 moves upwards. The wedge surfaces 6 of the wedge 7a move the clamping pieces 4 radially outwards, whereby their balls 9

come into contact with the inclined surface 14. Until the point " ^5p9 " is reached, the ^balls 9 can roll off the inclined surface 14 and rotate in their ball sockets 10. As a result, the ring surfaces 1B, 19, which surround the centering hole 2 or the centering pin 13, are pressed against one another with a high clamping force V.

To increase the clamping force V, you can change the angle

μgr;, which the inclined surface 14 encloses with the carrier axis A &igr; and which in the embodiment shown is 45°,

An increase in the clamping force can also be achieved by inclining the wedge surfaces 5, 6 at a &igr; smaller angle to the support axis A.

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Figures 2 and 3 show two variants of the embodiment shown in Figure 1. In this embodiment, in the area of each ball 9, a screw 20, 20' is inserted into a radial threaded bore 21, 21' of the centering set 13. This screw 20, 20' has a conical recess 1 *&diams; ·, which also forms a beveled surface that is inclined in a pointed spelt to the support axis A. However, it is important that the axis A1 of the screw 20, 20' is opposite the axis formed by the ball center point radial plane R towards the ring surface 19, so that the ball 9 comes to rest on the conical recess 14 on one side. The arrangement of the conical recesses 14" in the screws 20, 20' has advantages. If after a long period of use

If wear occurs on the conical recesses 1i»' during use of the tool, the screws can be easily replaced with new ones. It is also possible to manufacture the screws ZO, 20' from particularly wear-resistant material and to harden them. Hardening problems that may arise when hardening an inclined surface worked directly into the tool holder are thus avoided. In addition , torques can also be transmitted through the conical recesses Hi', so that additional devices for torque transmission such as the transverse grooves 16 and sliding blocks 17 described above can be omitted.

The embodiments shown in Figures 1, 2 and 3, in

bleach the centering projection 13 is hollow and surrounded by the centering recess 2 provided in the machine tool spindle 1, also have other significant advantages. !namely, the clamping parts U are pressed outwards, then the balls 9 on the bevel- fische H» also radially outward directed force components. This causes the hollow centering projection 13 to expand radially elastically and is pressed with its outer surface against the centering hole 2. The slight play required for inserting the cylindrical centering projection 13 into the

Centering recess 2 is required, this will

This results in a better positive connection between the centering projection 13 and the centering recess 2. This in turn results in an increase in the rigidity of the connection between the machine tool spindle 1 and the tool holder 12. In addition, the positioning accuracy is increased.

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In the embodiments shown in Figures U and 5, parts with the same function are designated with the same reference numerals as they were covered in the previously described embodiments. The above description therefore also applies analogously to the embodiments shown in Figures U and 5. In these embodiments too, it is possible to replace the inclined surfaces M* with conical depressions which are arranged on corresponding screws. In these embodiments, as in the previous embodiments, the conical depressions could also be arranged directly in the tool holder if necessary.

In the embodiment shown in Figure <», the clamping pieces U are arranged in a part 1' of the machine tool spindle 1 surrounding the centering projection 13. The actuating element in this case is a ring 7" which concentrically surrounds the part ¹¹ and is axially displaceable.

In the embodiment shown in Figure 5, the carrier 11 to be attached to the machine tool spindle ¹ is designed as a spindle attachment flange. It usually has a centering projection 22 in which the clamping parts <· are mounted so as to be radially displaceable. In this case, the tool holder 12' is provided with a centering bore 23 which fits onto the centering projection 22. All other parts correspond in structure and function to the parts of the embodiment shown in Figure 1.

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Claims (5)

f β I 1 t · Claims 1. Device for connecting a tool holder to a carrier, in particular a machine tool spindle, with a centering bore arranged on the carrier concentrically to a carrier axis and a centering projection, with at least two clamping pieces which can be displaced in a transverse recess of the carrier which runs radially to the carrier axis, with an actuating member which is axially movable on the carrier in the direction of the carrier axis and which acts on the first ends of the clamping pieces via wedge surfaces, with a centering projection &oacgr;&zgr;&ohgr; provided on the tool holder. a centering bore, which has inclined surfaces arranged at an acute angle to the carrier axis, on which the clamping pieces act with their second ends in the clamping position and thereby axially press ring surfaces, which each surround the centering projection or the centering bore, together, characterized in that at the second end (<fb) of each clamping piece (U) a ball (9) is arranged countersunk and rotatably mounted in a ball socket (10) provided in the clamping piece (U) , the depth (t) of which is slightly more than half the ball diameter (d), the ball diameter being dimensioned and the inclined surface (1U, 11»·) being arranged opposite the ball (9) in such a way that in the clamping position the ball (9) and the inclined surface (11», 1U ¹ ) touch at a force application point (P) which is at a distance from the edge (1<*a) at which the inclined surface (1U) in a axially parallel surface (13a). 2* Device according to claim 1, characterized in that the area of the respective end (<»a) of the clamping piece (i») surrounding the ball (9) is flanged towards the ball (9). > IIII I ₁ .. I Iff··· ·· ·· - 10 - 3. Device according to claim 1 or 2, characterized in that the balls (9) consist of hard metal. U. Device according to claim 1, 2 or 3, characterized in that the ball diameter (d) is approximately 2/3 of the diameter (D) of the cylindrically formed clamping piece (*»). 5. Device according to claim 1, characterized in that the inclined surface is formed by a conical recess (1U') of a screw (20, 20') which is screwed into a threaded bore (21, 21') in the tool holder (12) running radially to the carrier axis (A).