EP3520965A1 - Expanding mandrel assembly with pulldown effect - Google Patents

Abstract

A mandrel arrangement (1) for clamping a workpiece (9), comprising - an expandable mandrel (6), for engagement in a recess (23; 36) of the workpiece (9), - a counter bearing (4) for direct or indirect contact of the workpiece (9), - a relative to the mandrel (6) along an actuating axis (BA) movable actuator (7) with a spreading element (15), wherein by a relative movement of the expansion element (15) relative to the mandrel (6) along a Verspannrichtung (VR), which is parallel to the actuating axis (BA), the mandrel (6) is spreadable, and wherein the mandrel (6) relative to the counter bearing (4) along the actuating axis (BA) is designed to be movable, and- first elastic element (14), with which the mandrel (6) against the tensioning (VR) is biased away from the counter bearing (4) away from the counter bearing (4), characterized in that a base plate (8) is present on the a front bearing (12) f r is formed a rear bearing (24) an installation of the workpiece (9) and for an installation of the counter-bearing (4), that the base plate (8) has a recess (11; 30) is formed, in which the mandrel (6) along the actuating axis (BA) completely retractable behind the front bearing (12) in the recess (11, 30), and in that a tensioning device (2) is present, by means of which Actuator (7) along the clamping direction (VR) on the counter bearing (4) to and on the base plate (8) can be moved. The invention provides a mandrel arrangement that can be used well with a workpiece transport transverse to the axis of the mandrel.

Description

• einen aufspreizbaren Spanndorn, für einen Eingriff in eine Ausnehmung des Werkstücks,
• ein Konterlager, zur direkten oder indirekten Anlage des Werkstücks,
• einen gegenüber dem Spanndorn entlang einer Betätigungsachse beweglichen Betätiger mit einem Spreizelement, wobei durch eine Relativbewegung des Spreizelements gegenüber dem Spanndorn entlang einer Verspannrichtung, die parallel zur Betätigungsachse verläuft, der Spanndorn aufspreizbar ist, und wobei der Spanndorn relativ zum Konterlager entlang der Betätigungsachse beweglich ausgebildet ist, und
• ein erstes elastisches Element, mit welchem der Spanndorn gegenüber dem Konterlager entgegen der Verspannrichtung vom Konterlager weg vorgespannt ist.

The invention relates to a mandrel arrangement for clamping a workpiece, comprising

• an expandable mandrel, for engagement in a recess of the workpiece,
• a counter bearing, for the direct or indirect installation of the workpiece,
• a relative to the mandrel along an actuating axis movable actuator with a spreading element, wherein by a relative movement of the expansion element relative to the mandrel along a Verspannrichtung, which is parallel to the actuating axis, the mandrel is spreadable, and wherein the mandrel is designed to be movable relative to the counter bearing along the actuating axis , and
• a first elastic element, with which the mandrel opposite the counter bearing is biased against the clamping direction away from the counter bearing.

Such a mandrel arrangement is from the company publication " Spanndorne collet chuck "of Röhm GmbH, 89567 Sontheim / Brenz, DE, dated 09/2017, page 7017 , known.

For machining or measuring workpieces, it is generally necessary to hold the workpieces in a fixed position, so that the machining tools can perform the intended machining precisely to the workpiece, or the measurement data can be determined with good precision.

An attachment of a workpiece can be done in particular with a so-called mandrel. The mandrel is introduced relative to the workpiece axially in a recess of the workpiece and radially spread. This jams the mandrel in the workpiece and can hold it in position. The spreading of the mandrel can be done with a wedge-shaped expansion element, which is moved in the axial direction in the mandrel, such as by screwing. The braced workpiece is typically on a counter bearing, which is formed on a lower part of the mandrel component. Such a mandrel is for example from the Catalog "Control Elements | Standard Elements" of the Heinrich Kipp Werk KG, 72172 Sulz am Neckar, DE, page 767, edition 2016 , known.

Such mandrels can accurately position a workpiece transverse to the axis of the mandrel. For an exact positioning also in the axial direction usually an additional clamping device is used, which presses the workpiece onto the counter bearing.

From the company publication of the Röhm GmbH, loc. Cit., A mandrel arrangement is known, in which a sleeve clamping mandrel is displaceably mounted on a base body via a resilient pressure piece. In the sleeve mandrel a clamping cone is arranged, which has an intermediate piece can be moved axially relative to the main body. By pulling down the clamping cone both the sleeve mandrel is spread radially, as well as drawn axially to the body.

With this mandrel arrangement, a workpiece can also be clamped in the axial direction by being used on the base body, so that an additional clamping device is not necessary.

The clamping mandrel arrangement presented in the company publication of Röhm GmbH, loc. Cit., Is intended in particular for substantially round workpieces which are rotated during machining, for example by turning or toothing machining, for example by hobbing. Such workpieces are typically introduced for attachment to the mandrel assembly along the axis of rotation of the workpiece or along the axis of the mandrel to the mandrel and placed on the mandrel, and then the mandrel is spread. After machining, the mandrel is first relaxed and then lifted the workpiece along the axis of the mandrel and led away. For this application, the known mandrel arrangement can also be used well.

In other applications, however, a workpiece transport axis along the axis of the mandrel is often not provided, for example for cost reasons, or would be cumbersome for the process flow in the context of the proposed processing. It may simply be too little space for an axial lifting of the workpiece, especially in manual workpiece handling. However, then often a workpiece transport axis is arranged transversely to the axis of the mandrel, or would be more efficient for the process flow, such as to perform a further machining on the workpiece at the same axial position, but at a different lateral position. Also, often for reasons of space, a workpiece feed from the side is particularly easy set up, again in particular with manual workpiece handling. In such applications, however, the mandrel would block the workpiece against a process.

Object of the invention

The invention has for its object to present a mandrel arrangement that can be used well with a workpiece transport transverse to the axis of the mandrel.

Brief description of the invention

This object is achieved in a surprisingly simple and effective manner by a mandrel arrangement of the type mentioned, which is characterized
that a base plate is present, on which a front bearing is formed for a bearing of the workpiece and a rear bearing for a bearing of the counter bearing,
that the base plate forms a recess, in which the mandrel along the actuating axis is completely retractable into the recess behind the front bearing,
and that a tensioning device is provided, by means of which the actuator can be moved along the clamping direction to the counter bearing to and on the base plate.

In the context of the invention, an indirect installation of the workpiece is set up on the counter bearing, namely via the base plate. The base plate supports itself with a rear bearing at the counter bearing, and provides with the front bearing a plant for the workpiece. At the same time, the base plate forms a recess into which the mandrel can be inserted or retracted. The recess is large enough that the Mandrel (and possibly other parts that protrude axially beyond the mandrel) completely behind the front bearing or a corresponding front bearing plane, which typically runs perpendicular to the actuating axis / Verspannrichutng, can be withdrawn.

This makes it possible to leave the workpiece applied to the front bearing and to move transversely to the actuating axis / Verspannrichtung (or parallel to the front bearing plane) on the base plate, such as to reposition the workpiece for various sequential operations or to load the workpiece and to discharged. When retracted into the recess mandrel this does not interfere with the movement of the workpiece. For repositioning or loading and unloading of the workpiece, it is not necessary to lift it along the actuating axis / clamping direction of the base plate. A corresponding workpiece transport axis is not necessary. In addition, a machining station or measuring station on which the mandrel arrangement is installed, with a reduced space requirement axially above the mandrel (relative to its position with clamped workpiece) or axially above the workpiece (based on its braced on the base plate position) get along.

The invention thus simplifies workpiece transport transversely to the actuating axis of the mandrel, both for automated (mechanical) and for manual workpiece handling.

Typically, the actuator extends through the counter bearing and protrudes into the base plate or through the base plate. The clamping device typically engages the actuator and the component of the counter bearing.

Preferred embodiments of the invention

A preferred embodiment of a mandrel arrangement according to the invention provides that the actuator is formed with a pull rod, and the tensioning device on movement of the actuator along the clamping direction by means of the pull rod, the spreader pulls on the counter bearing, in particular wherein the pull rod through the counter bearing through to Chuck is guided. This makes a particularly compact and robust design possible. Alternatively, more complex power transmission, such as with a push rod and a C-shaped throw, come into consideration.

In a particularly advantageous embodiment, a second elastic element is present, with which the actuator is biased against the mandrel opposite to the clamping direction. By means of the second elastic element, the expansion element is automatically pushed back axially against the clamping direction when the tensioning device is unloaded, so that the mandrel returns to a non-spread-open position. The radial strain of the workpiece is then released very reliable in relaxation of the clamping device; In particular, no access from above (from the side facing away from the counter bearing) through the workpiece on the mandrel necessary to pick up (about manually) a friction-induced self-locking radial strain of the workpiece. This embodiment is therefore particularly useful when the recess of the workpiece is formed as a blind hole, and therefore access from the top of the mandrel is not possible. The second elastic element may in particular be designed as a compression spring.

An advantageous development of this embodiment provides that a first spring rate of the first elastic element is greater than a second spring rate of the second elastic element. This ensures that in the course of the tensioning of the tensioning device, ie when moving the actuator along the clamping direction towards the counter bearing, first of all the radial spreading of the mandrel can take place (and thereby the workpiece is taken), and then above all (when gripped workpiece) the axial pulling down of the workpiece can take place. The pulling down of the workpiece thus takes place only when it is securely gripped, whereby a particularly reliable and defined attachment of the workpiece is achieved. If the spreading of the mandrel to contact the workpiece requires a significant force, this should be taken into account in the design of the spring hardness, and the first spring hardness of the first elastic member to be chosen correspondingly larger.

In a preferred development of this embodiment, the second elastic element is formed with a helical spring which presses the expansion element away from a base part of the mandrel against the clamping direction. This embodiment is particularly simple and compact. The coil spring is typically completely gripped by the mandrel.

Also preferred is an embodiment in which the expansion element is formed with one or more cone-shaped surfaces and / or the mandrel forms one or more cone-shaped mating surfaces for the expansion element. By the cone-shaped surfaces and / or mating surfaces, the axial movement of the actuator in the clamping direction can be deflected in a radial movement for the spreading of the mandrel in a simple and reliable manner. Cone-sheath-shaped here means that the surface or counter surface describes at least a part of the surface of a cone sheath. Instead of cone-shaped surfaces and other types of wedge-shaped surfaces or mating surfaces are possible, however, cone-shaped surfaces are usually very easy to manufacture and have a very low tilting tendency.

Also advantageous is an embodiment in which the mandrel is formed substantially sleeve-shaped, wherein at least the spreader for spreading the mandrel in the mandrel is axially movable. The sleeve shape allows the accommodation of functional components in the interior of the mandrel, such as a second elastic member and parts of the actuator, and thus allows a particularly compact structure.

In a preferred embodiment, the mandrel is formed with a plurality of expanding jaws, which are separated by substantially parallel to the operating axis extending column. The expansion jaws are typically connected at one axial end to a foot part (on the side of the counter bearing), and can bend in a substantially radial direction at the opposite axial end (on the side facing away from the counter bearing). This type of mandrel is simple and inexpensive to manufacture. As an alternative to expanding jaws, it is also possible, for example, for expanding balls to be pressed radially outward by a wedge-shaped, in particular cone-shaped, spreading element.

An advantageous embodiment provides that the recess of the base plate is formed with a stop which limits an axial insertion of the mandrel into the base plate. This facilitates the handling of the mandrel arrangement; the retracted mandrel can not fall through the base plate and be lost by mistake.

As an alternative, it is provided in one embodiment that the recess of the base plate is formed continuously, so that the mandrel can be passed completely through the recess of the base plate. The continuous configuration of the recess relates to the (maximum) radial width of the mandrel, with respect to which the recess has a larger (minimum) radial width to the mandrel completely to carry out. A clamping assembly (formed from the tensioning device, the counter bearing, the actuator and the mandrel) can be easily offset on the base plate between different through recesses of the base plate, in particular to handle a different type of workpiece. Furthermore, the base plate in the axial direction can be made particularly thin and thus save material cost, especially in the axial direction thinner than the mandrel is long. The mandrel may be pulled back behind the front bearing so that it (at least partially) on the opposite side out of the base plate is led out.

Also advantageous is an embodiment in which the base plate, in particular by means of the recess in the base plate, forms a guide for the mandrel. Thereby, the precision in the attachment of the workpiece can be improved, and also the handling of the mandrel arrangement can be facilitated, for example during assembly or during clamping of the clamping device.

In an advantageous embodiment, it is provided that a third elastic element is present, by means of which the counter bearing is biased against the base plate in abutting counter bearing and rear bearing along the actuating axis of the base plate away. This (with the tensioning device relaxed) retraction of a terminal ensemble (formed by the entirety of mandrel, actuator, counter bearing and clamping device) is facilitated, in particular to retract the terminal ensemble or the mandrel behind the front bearing of the base plate.

Also preferred is an embodiment in which the clamping device is formed with an eccentric lever. An eccentric lever is simple and safe to handle. Alternatively, the clamping device may be formed, for example, with a cone screw.

Also advantageous is an embodiment in which one or more profiled contact surfaces, in particular serrated contact surfaces, are formed on the mandrel for engagement with the wall of the recess of the workpiece. Thereby, the friction between the mandrel and the workpiece can be increased, so that a better grip of the mandrel is achieved in the recess of the workpiece. The attachment of the workpiece by means of the mandrel arrangement is thereby more reliable.

The scope of the present invention also includes the use of a tensioning mandrel arrangement according to the invention, which is characterized in that, with the tensioning device inserted into the recess of the workpiece, the actuator is moved along the clamping direction so far towards the counterbearing, that the mandrel is spread in the recess spread and the workpiece is applied without play to the base plate and thus indirectly to the counter bearing. The attachment of the workpiece to the base plate is robust, and both in the axial direction and across it precise and well reproducible. Accordingly, machining processes and measurements are possible with great accuracy.

Preference is given to a variant of this use, in which the workpiece is subjected to a drilling operation and / or a milling operation when there is no play on the base plate. In these operations, a backlash-free alignment of the workpiece is particularly important. During the drilling and / or milling, the workpiece is held stationary, and in particular not rotated.

Further advantages of the invention will become apparent from the description and the Drawing. Likewise, according to the invention, the above-mentioned features and those which are still further developed can each be used individually for themselves or for a plurality of combinations of any kind. The embodiments shown and described are not to be understood as exhaustive enumeration, but rather have exemplary character for the description of the invention.

Detailed description of the invention and drawing

Fig. 1

einen schematischen Längsschnitt durch eine erste Ausführungsform einer erfindungsgemäßen Spanndorn-Anordnung, mit einer durchgehenden Ausnehmung an der Grundplatte, in einem entspannten Zustand der Spannvorrichtung;

Fig. 2

die Spanndorn-Anordnung von Fig. 1, in einer schematischen Seitenansicht;

Fig. 3

die Spanndorn-Anordnung von Fig. 1 im schematischen Längsschnitt, im verspannten Zustand der Spannvorrichtung;

Fig. 4

einen schematischen Längsschnitt durch eine zweite Ausführungsform einer erfindungsgemäßen Spanndorn-Anordnung, in einem entspannten Zustand der Spannvorrichtung, mit einem bis an einen Anschlag in eine Ausnehmung der Grundplatte zurückgezogenem Spanndorn;

Fig. 5

die Spanndornanordnung von Fig. 4, mit an die Grundplatte angedrücktem Konterlager, in einem entspannten Zustand der Spannvorrichtung;

Fig. 6

die Spanndornanordnung von Fig. 5, mit der Spannvorrichtung im verspannten Zustand;

Fig. 7

einen Spanndorn im schematischen Querschnitt mit profilierten Kontaktflächen für die Erfindung.

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

Fig. 1

a schematic longitudinal section through a first embodiment of a mandrel arrangement according to the invention, with a continuous recess on the base plate, in a relaxed state of the clamping device;

Fig. 2

the mandrel arrangement of Fig. 1 in a schematic side view;

Fig. 3

the mandrel arrangement of Fig. 1 in a schematic longitudinal section, in the clamped state of the clamping device;

Fig. 4

a schematic longitudinal section through a second embodiment of a mandrel arrangement according to the invention, in a relaxed state of the clamping device, with a to a stop in a recess of Base plate retracted mandrel;

Fig. 5

the mandrel arrangement of Fig. 4 with counter-bearing pressed against the base plate, in a relaxed state of the tensioning device;

Fig. 6

the mandrel arrangement of Fig. 5 , with the clamping device in the clamped state;

Fig. 7

a mandrel in a schematic cross section with profiled contact surfaces for the invention.

The Fig. 1 shows in a schematic longitudinal section and Fig. 2 in a side view at 90 ° rotation relative to the Fig. 1 a mandrel arrangement 1 according to the invention.

The mandrel arrangement 1 comprises a tensioning device 2 (here formed with an eccentric lever 3), a counter bearing 4 (here formed on a base element 5 on which the eccentric lever 3 is mounted), a here substantially sleeve-shaped mandrel 6, an actuator 7 and a base plate 8. The entirety (contiguous assembly) of clamping device 2, counter bearing 4, mandrel 6 and actuator 7 is also referred to as terminal assembly 10. The mandrel arrangement 1 is used to attach a workpiece 9 on the base plate 8. The base plate 8 is typically fixed in place, such as on a machine frame (not shown).

A front part of the clamp ensemble 10, namely the mandrel 6 and a front part of the actuator 7, protrudes through a recess 11 of the base plate 8 therethrough. The recess 11 acts as a guide for the mandrel 6, so in that it is movable parallel to a clamping direction VR or along an actuation axis BA of the actuator 7 in the base plate 8.

The clamp assembly 10 is loosely inserted into the recess 11 of the base plate 8 in the state shown (with a relaxed clamping device 2), and could easily be pulled down as far as desired from the recess 11. In particular, the clamp assembly 10 could be pulled down so far that the mandrel 6 and the clamp assembly 10 can be completely withdrawn entirely behind a front bearing 12 of the base plate 8, which is here formed with a front bearing plane 13; the recess 11 is thus continuous with respect to the mandrel 6 (or its radial width). Upon complete withdrawal behind the front bearing 12, a workpiece bearing against the front bearing 12 could be moved along the front bearing 12 in a barrier-free manner (not shown in greater detail).

Furthermore, the terminal ensemble 10 could be completely pulled out of the recess 11, in particular to put the terminal assembly 10 to another recess of the base plate 8 or to a recess of another base plate (not shown in detail).

A first elastic element 14, here designed as a coil spring 14 a under compressive stress, presses the mandrel 6 counter to the clamping direction VR away from the counter bearing 4. The first elastic element 14 is supported here on the base element 5 or on the counter bearing 4 and on a foot part 21 of the mandrel 6.

At an upper (front) end of the actuator 7, an expansion element 15 is formed, which is formed with cone-shaped surfaces 16. These are based on cone-shaped mating surfaces 17 in the interior of the mandrel 6 from, namely on the inner sides of expansion jaws 18 a, 18 b, the are separated by axially extending column 19. The column 19 are at the bottom in relief holes 20 on to prevent cracking during spreading of the expansion jaws 18a, 18b. The expanding jaws 18a, 18b are from the common foot part 21 of the mandrel 6 from.

A second elastic element 22, here likewise designed as a coil spring 22a under compressive stress, pushes the expansion element 15 away from the clamping mandrel 6 against the clamping direction VR; the second spring element 22 is supported here on the foot part 21 of the mandrel 6 and the spreader 15 from.

With the tensioning device 2, the actuator 7 can be moved axially along the actuation axis BA relative to the base element 5 or the counter bearing 4. In the position shown, the actuator 7 and thus also the expansion element 15 is extended relatively far upwards, ie against the Verspannrichtung VR away from the counter bearing 4, corresponding to a relaxed state of the tensioning device 2. The expansion element 15 exercises in the relaxed state only a small radial force on the wedge effect of the cone-shaped surfaces 16 on the expanding mandrel 6, so that the expansion jaws 18a, 18b are pressed only slightly radially outward. In this state, the expanding mandrel 6 can be easily introduced or executed with radial clearance in a recess 23 of the workpiece 9.

In the situation shown, the workpiece 9 is loosely fitted with its recess 23 on the mandrel 6 in order to prepare the clamping of the workpiece 9 on the base plate 8.

To clamp the workpiece 9, the terminal ensemble 10 is gripped by an operator and pressed up against the base plate 8. In this case, the counter bearing 4 and a rear bearing 24 of the base plate 8 come to a mutual investment. Likewise, the workpiece 9 is up to the Base plate 8 pushed up, so that a lower workpiece side 25 comes to rest on the front bearing 12 of the base plate 8; As a result, the mandrel 6 projects slightly deeper into the recess 23 of the workpiece 9. In this situation, the tensioning device 2 is tensioned; the tensioned state of the tensioning device 2 is in Fig. 3 shown.

By pivoting the eccentric lever 3 to the left was a rotational axis DA of the eccentric lever 3, to which the actuator 7 is connected, moved relative to the base member 5 axially downwards, so that the actuator 7 and in particular its expansion element 15 in Verspannrichtung VR on the counter bearing 4 were drawn.

Due to a relatively small second spring hardness of the second elastic member 22 compared to a first spring hardness of the first elastic member 14, the mandrel 6 has initially remained almost stationary during this movement of the expansion element 15 relative to the counter bearing 4, because the relatively hard first elastic element 14th has the mandrel 6 away from the counter bearing 4. By contrast, the expansion element 15 could overcome the comparatively low force of the second elastic element 22 and moved relative to the mandrel 6 down and spread the spreading jaws with the cone-shaped surfaces 16 while continuing to spread radially.

However, as soon as the spreading jaws got into contact with the inside of the recess 23 of the workpiece 9, the spreading element 15 could no longer be moved downwards relative to the clamping mandrel 6 or only with a very large resistance. A further movement of the actuator 7 in the clamping direction VR down then led to now that the mandrel 6 was pulled against the force of the first spring element 14 in the clamping direction VR down. Since the clamping jaws of the mandrel 6 are in compression and thus in frictional connection with the inside of the recess 23 of the workpiece 9, while the workpiece 9 was pulled down with and thus pressed against the base plate 8. The actuator 7 was brought under considerable tension, and thus acts as a tie rod 7a.

In the illustrated braced state of the tensioning device 2, therefore, the workpiece 9 is not secured against the base plate 8 only by the clamping mandrel 6 which locks in the form-locking connection, but also sits without play on the base plate 8 with respect to the axial direction (see actuating axis BA) on. An axial movement 27 of the workpiece 9 is not possible due to the frictional connection with the mandrel 6. In this state, the workpiece 9 is typically subjected to a machining, in particular a drilling or milling, or even a measurement, in particular a measurement of its outer dimensions.

When relaxing the tensioning device 2, ie a pivoting back of the eccentric lever 3 in the in Fig. 1 shown position, the axial strain of the workpiece 9 is released against the base plate 8, wherein the first elastic member 14 is again (largely) relaxed. The second elastic element 22 then supports the cancellation of the radial tension of the spread-apart clamping jaws of the mandrel 6 by pushing the expansion element 15 upwards away from the cone-shaped mating surfaces 17 of the mandrel 6.

The Fig. 4 shows a second embodiment of a mandrel arrangement according to the invention 1. Only the essential differences from the first embodiment will be explained.

In this embodiment, a recess 30 for receiving the mandrel 6 is formed in the base plate 8, which forms a shoulder-like stop 31 on the side facing the clamping device 2. The mandrel 6 can therefore not be guided down through the recess 30; the recess 30 is thus with respect to the mandrel. 6

(or its radial width) not continuous. Although the recess 30 passes into an opening 32 through which the actuator 7 and the first elastic element 14 are passed or can be, but this opening 32 is not wide enough for the mandrel 6. The clamp assembly 10, comprising the clamping device 2, the counter bearing 4, the actuator 7 and the mandrel 6, is here permanently on the base plate 8 and its recess 30 is arranged by the base plate 8 in the region of the stopper 31 engages on both sides; The clamp assembly 10 could only be removed by disassembly of the base plate 8.

In the embodiment shown, furthermore, the counter bearing 4 is formed on a collar element 33, which is supported on the base element 5. A third elastic element 34, again formed here as a coil spring 34a under compressive stress, biases the base plate 8 against the clamping direction VR against the counter bearing 4; Base plate 8 and counter bearing 4 are pushed apart, so to speak. The third elastic element 34 engages here on the counter bearing 4 and on a recessed shoulder 35 of the base plate 8, wherein the shoulder 35 is beyond the rear bearing 24 at.

By the action of the third elastic element 34, the actuator 7 including the expansion element 15 and also the mandrel 6 are drawn into the recess 30, substantially to the stop 31. The tensioning device 2 is in a relaxed state. The mandrel 6 and the terminal ensemble 10 in total are withdrawn behind the front bearing 12 and the associated front bearing plane 13. This makes it possible to move the workpiece 9 on the first bearing 12 in the lateral direction transversely to the actuation axis BA, cf. lateral displacement 26.

In the workpiece 9 here designed as a blind hole recess 36 is formed. For clamping the workpiece 9 on the base plate 8 must the workpiece 9 at least approximately with its recess 36 on the mandrel 6 and over the recess 30 of the base plate 8 are arranged.

For clamping the workpiece 9, the clamp assembly 10 is then pushed relative to the base plate 8 by an operator up until the counter bearing 4 abuts the rear bearing 24 of the base plate 8, see. For this Fig. 5 , In this case, the third elastic element 34 is compressed against its spring force. The mandrel 6 penetrates into the recess 36 of the workpiece 9; Typically, the workpiece 9 is held manually by the operator, so that it does not dodge upwards, if already a noticeable friction between the mandrel 6 and the inner wall of the recess 36 of the workpiece 9 should occur.

Then the tensioning device 2 is tensioned, cf. Fig. 6 By the eccentric lever 3 is pivoted to the left. As a result, the actuator 7 together with the spreading head 15 in the clamping direction VR down to the counter bearing 4 is pulled. As described in the first embodiment, it comes first of all to a spreading of the mandrel 6, and after reaching the pressure of the expanding jaws of the mandrel 6 in the recess 36 of the workpiece 9, the workpiece 9 is pulled down to the base plate 8. When abutting the first bearing 12 of the base plate 8 and the lower side of the workpiece 25, the workpiece 9 is braced against the base plate 8. Here, the actuator 7 is set under considerable tension. The workpiece 9 is secured against lateral displacement 26 by positive locking by means of the mandrel 6, which engages in both recesses 36, 30, and secured against axial movement 27 by means of frictional connection by means of the expanding jaws of the mandrel 6. In this state, the workpiece 9 is typically again subjected to machining or measurement. The processing preferably takes place when the workpiece 9 is at rest.

When turning back the eccentric lever 3 in the in Fig. 4 shown position helps the second elastic tensioning device 22 when canceling the spreading of the expanding jaws of the mandrel 6, and the third spring element 34 helps to retract the mandrel 6 and the Klemmsembles 10 behind the front bearing 12 and thus completely out of the recess 36 of the workpiece 9 out , so that this can be moved again in the lateral direction on the first bearing 12 of the base plate 8, cf. lateral displacement 26, for example for a workpiece change. Likewise, the workpiece 9 can then be lifted in the axial direction, cf. axial movement 2, if desired.

Fig. 7 shows in schematic cross section a mandrel 6 for the invention. At its clamping jaws 18a, the mandrel 6 radially outwardly profiled contact surfaces 40, which are serrated here with down (to the foot part 21 of the mandrel 6 back) directed teeth are formed. With the profiled contact surfaces 40, an improved hold in the recess of a workpiece is possible.

LIST OF REFERENCE NUMBERS

1

Mandrel assembly

2

jig

3

Cam

4

counterrevolutionary camp

5

base element

6

mandrel

7

actuator

7a

tie rods

8th

baseplate

9

workpiece

10

terminal Ensemble

11

Recess of the base plate (continuous)

12

front bearing

13

front storage level

14

first elastic element

14a

Coil spring (first elastic element)

15

Spreitzelement

16

conical surfaces

17

conical counter surfaces

18a, 18b

Moveable

19

gap

20

relief well

21

Foot part (mandrel)

22

second elastic element

22a

Coil spring (second elastic element)

23

Recess in the workpiece (continuous)

24

rear warehouse

25

lower side (workpiece)

26

lateral displacement

27

axial movement

30

Recess in the base plate (not continuous)

31

attack

32

Through opening

33

collar element

34

third elastic element

34a

Coil spring (third elastic element)

35

rear warehouse

36

Recess in the workpiece (blind hole)

40

profiled contact surfaces

BA

operating axis

THERE

Rotary axis (bearing axis of the actuator on the eccentric lever)

VR

clamping direction

Claims (16)

Mandrel arrangement (1) for clamping a workpiece (9), comprising - An expandable mandrel (6), for engagement in a recess (23, 36) of the workpiece (9), - a counter bearing (4) for direct or indirect abutment of the workpiece (9), - A relative to the mandrel (6) along an actuating axis (BA) movable actuator (7) with a spreading element (15), wherein by a relative movement of the expansion element (15) relative to the mandrel (6) along a Verspannrichtung (VR) parallel to the actuating axis (BA) extends, the mandrel (6) is spreadable, and wherein the mandrel (6) relative to the counter bearing (4) along the actuating axis (BA) is designed to be movable, and a first elastic element (14), with which the mandrel (6) is biased away from the counter bearing (4) against the tensioning direction (VR) in relation to the counter bearing (4), characterized,
that a base plate (8) is provided at the a front bearing (12) for a plant of the workpiece (9) and a rear bearing (24) for an abutment of the counter-bearing (4) is formed,
that the base plate (8) has a recess (11; 30) forms, in which the mandrel (6) along the actuation axis (BA) all the way up behind the front bearing (12) in the recess (11; 30) is retractable,
and that a tensioning device (2) is provided, by means of which the actuator (7) can travel along the tensioning direction (VR) onto the counter bearing (4). to and on the base plate (8) can be moved. Mandrel arrangement (1) according to claim 1, characterized in that the actuator (7) with a pull rod (7a) is formed, and the clamping device (2) upon movement of the actuator (7) along the Verspannrichtung (VR) by means of the tie rod (7a) pulls the expansion element (15) towards the counter bearing (4),
in particular wherein the pull rod (7a) is guided through the counter bearing (4) to the tensioning device (2). Mandrel arrangement (1) according to any one of the preceding claims, characterized in that a second elastic element (22) is present, with which the actuator (7) against the mandrel (6) is biased against the Verspannrichtung (VR). Mandrel arrangement (1) according to claim 3, characterized in that a first spring rate of the first elastic element (14) is greater than a second spring rate of the second elastic element (22). Mandrel arrangement (1) according to one of claims 3 or 4, characterized in that the second elastic element (22) is formed with a helical spring (22a) which separates the spreading element (15) from a foot part (21) of the mandrel (6 ) pushes away against the clamping direction (VR). Mandrel arrangement (1) according to one of the preceding claims, characterized in that the expansion element (15) is formed with one or more cone-shaped surfaces (16) and / or the mandrel (6) one or more cone-shaped mating surfaces (17) for the Spreading element (15) is formed. Mandrel arrangement (1), characterized in that the mandrel (6) is substantially sleeve-shaped, wherein at least the expansion element (15) for spreading the mandrel (6) in the mandrel (6) is axially movable. Mandrel arrangement (1) according to one of the preceding claims, characterized in that the mandrel (6) with a plurality of expanding jaws (18a, 18b) is formed, which are separated by substantially parallel to the actuating axis (BA) extending column (19) , Mandrel arrangement (1) according to one of claims 1 to 8, characterized in that the recess (30) of the base plate with a stop (31) is formed, which limits an axial insertion of the mandrel (6) in the base plate (8) , Mandrel arrangement (1) according to one of claims 1 to 8, characterized in that the recess (11) of the base plate (8) is formed continuously, so that the mandrel (6) completely through the recess (11) of the base plate (8 ) can be passed. Mandrel arrangement (1) according to one of the preceding claims, characterized in that the base plate (8), in particular by means of the recess (11; 30) in the base plate (8), forms a guide for the mandrel (6). Mandrel arrangement (1) according to any one of the preceding claims, characterized in that a third elastic element (34) is present, by means of which the counter bearing (4) relative to the base plate (8) in abutting counter bearing (4) and rear bearing (24) along the actuating axis (BA) is biased away from the base plate (8), Mandrel arrangement (1) according to one of the preceding claims, characterized in that the clamping device (2) is formed with an eccentric lever (3). Mandrel arrangement (1) according to one of the preceding claims, characterized in that on the mandrel (6) one or more profiled contact surfaces (40), in particular serrated contact surfaces (40), for abutment against the wall of the recess (23; of the workpiece (9) are formed. Use of a mandrel arrangement (1) according to one of the preceding claims, characterized in that when the mandrel (6) is inserted into the recess (23; 36) of the workpiece (9) with the clamping device (2), the actuator (7) runs along the Tensioning direction (VR) so far on the counter bearing (4) is moved to that of the mandrel (6) in the recess (23; 36) spread is clamped and the workpiece (9) backlash to the base plate (8) and thus indirectly the counter bearing (4) is applied. Use according to claim 15, characterized in that at play on the base plate (8) fitting the workpiece (9) the workpiece (9) is subjected to a drilling and / or a milling.

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