DE102015114212B4 - Arrangement for clamping a rotatable workpiece - Google Patents

Abstract

Arrangement for clamping a rotatable workpiece, containing a workpiece holder (4) with a rotatable workpiece holder (41) and a quill (42) opposite on a machine bed (3) for clamping the workpiece (7) on a between the workpiece holder (41) and the Machine axis (43) running on the quill (42), the quill (42) having an operative connection to a quick-release clamp (5) in a tailstock (1) which can be moved and clamped on a linear guide (31), with which the quill (42) is moved along the quill (42). Machine axis (43) can be moved between a clamping position and a release position of the workpiece (7), characterized in that - the quill (42) is accommodated in the tailstock (1) so that it can roll along the machine axis (43), - the quill (42) has a bearing plate (56) orthogonal to the machine axis (43) for establishing the operative connection to the quick release (5), and the quick release (5) contains a lever mechanism (51, 52, 53, 54) on which a terminal crank pin (55) is inserted a lateral groove-shaped recess (561) in the bearing plate (56) engages in order to axially displace the quill (42) by means of the lever movement by means of the bearing plate (56), - the tailstock (1) and the bearing plate (56) have adjacent vertical surfaces, one surface of which has a guide channel (58) with at least one upper locking point (584), the guide channel (58) being assigned a horizontally engaging sliding pin (566), and the other surface having a means (565) for horizontally movable mounting of the Sliding pin (566), - the guide channel (58) in one vertical surface has an inner wall contour (581) and an outer wall contour (582) for guiding the sliding pin (566) in a circumferential trajectory with at least two characteristic points: - the upper latching point (584), at which the quill (42), guided by the sliding pin (566), can be locked in the release position at least by gravity, and a lower latching point (585) at which the movement of the quill (42) is at least gravity-driven. is limited downwards in the clamping position.

Description

The invention relates to an arrangement for clamping a rotatable workpiece, containing a workpiece holder with a rotatable workpiece holder and a quill opposite on a machine bed for clamping the workpiece, the quill having an operative connection to a quick-release clamp in a tailstock that can be moved and clamped on a linear guide in which the quill can be moved along a machine axis between a clamping position and a release position for the workpiece. It is preferably used in measuring machines with vertically rotatable workpiece holders, especially for optical measuring machines.

From the disclosure document DE 10 2012 104 008 A1 Such a measuring machine is known. The machine axis, which runs between a headstock and a tailstock, is advantageously arranged vertically here, so that elongated rotatable workpieces, such as gear shafts, machine axes, etc., can be rotated about the vertically oriented workpiece axis for optical measurement. Compared to a horizontal holder, this has the advantage that workpieces with a small diameter in terms of their longitudinal extent, which are stored several times in their intended use, cannot show any deflection when held vertically. Furthermore, the radial approach of measuring devices, such as. B. the pivoting of a mechanical measuring probe can be done completely independently of weight forces or their moments. Compared to a horizontal arrangement, the vertical surfaces are also significantly less sensitive to contamination, which is beneficial to the accuracy of the measuring machines.

The workpiece is attached to the rotating headstock of the measuring machine, in which it can be clamped or clamped. In addition, a tailstock is provided opposite, with which the free end of the workpiece can be centered or supported. For this purpose, the tailstock is mounted so that it can move vertically on vertical surfaces of the machine bed, so that its position can be adjusted according to the length of the workpiece. Depending on the length of the workpiece, the tailstock can be clamped at any position on the vertical surfaces of the machine bed. For centering or supporting purposes, the tailstock has a rotating centering center that can exert a defined force on the clamped workpiece. How the rotating centering center is attached to the tailstock is not described.

Tailstocks known from the prior art, such as those found mainly on lathes, are usually accommodated on the machine bed so that they can be moved horizontally. They are used for centering, supporting or clamping workpieces that are at least partially rotationally symmetrical along the horizontal machine axis. These tailstocks have a quill to hold the centering center or other clamping devices or tools. The quill is movably accommodated in the tailstock along the machine axis and can be positioned relative to the workpiece using an adjusting device when the tailstock is clamped.

From the patent specification DE 508 526 Such a tailstock is known. A quill with a centering point is accommodated in the tailstock housing, which can be moved relative to the workpiece on the machine axis using a threaded spindle driven by a handwheel.

In contrast to the horizontal arrangement of the machine axis, in which gravity acts orthogonally to the machine axis, the vertical arrangement generally requires measures to prevent uncontrolled gravity-related movement of the quill along the machine axis. Would that from the aforementioned DE 508 526 If a known tailstock is used on a vertical machine axis, the movement could be inhibited by gravity, for example with a threaded spindle whose thread pitch is sufficiently small. However, the use of such a threaded spindle also prevents quick and easy positioning of the quill, for example in a lower and upper end position, and thus quick and convenient clamping and unclamping of the workpiece.

With one in the patent specification US 4,621,551 A With the quill drive described, the two end positions are assumed by means of a hydraulic drive. The end of the quill opposite the headstock is hydraulically sealed in the tailstock and is used as a hydraulic cylinder. A switch can be used to switch between two hydraulic circuits. In each of the circuits, the quill is moved to one of its respective end positions, in which the workpiece is either clamped or unclamped. Hydraulic solutions are not suitable for measuring machines because they are very complex and cost-intensive to implement and there is always a risk of contamination due to the hydraulic oil.

In addition to a variety of more or less complex hydraulic or electro-hydraulic solutions for positioning the quill purely mechanical solutions are also known from the prior art.

With one in the display document DE 1 123 180 A With the quick adjustment described, the quill can be quickly moved back and forth between two end positions using an additional mechanism located on the tailstock. In addition to the existing handwheel on the threaded spindle, there is an actuating lever. The actuating lever operates an eccentric, which is accommodated in the tailstock about an axis of rotation arranged perpendicular to the machine axis. The eccentric acts parallel to the machine axis on a sliding piece that is operatively connected to the quill via a spring. With the sliding piece, the quill can be quickly moved between two end positions, regardless of the threaded spindle drive, so that the workpiece can be quickly clamped and unclamped. The disadvantage of this solution is that the end position for unclamping the workpiece must be set by the operator without the support of a driving force. In the case of a vertical arrangement of this quick adjustment, this end position could not be maintained without additional precautions.

The object of the invention is to find a new possibility for a workpiece holder with a rotatable workpiece holder, in particular for an arrangement for optically measuring a rotatable workpiece, in which a tailstock that can be moved in a linear guide on a vertical machine bed has a quill for quick clamping and unclamping of the workpiece between a clamping position and a release position should be simple and easy to operate, especially with one hand.

According to the invention, the object is achieved in an arrangement for clamping a rotatable workpiece, containing a workpiece holder with a rotatable workpiece holder and a quill opposite on a machine bed for clamping the workpiece on a machine axis running between the workpiece holder and the quill, the quill being in one on a linear guide movable and clampable tailstock has an operative connection to a quick release, with which the quill can be moved along the machine axis between a clamping position and a release position of the workpiece, solved in that the quill is accommodated in the tailstock so that it can be rolled along the machine axis, so that the quill has a to Machine axis has orthogonal bearing plate for producing the operative connection to the quick release and the quick release contains a lever mechanism on which a terminal crank pin engages in a lateral groove-shaped recess in the bearing plate in order to axially displace the quill by means of the lever movement by means of the bearing plate, that the tailstock and the Bearing plate have adjacent vertical surfaces, one surface of which has a guide channel with at least one upper locking point, the guide channel being assigned a horizontally engaging sliding pin, and the other surface having a means for horizontally movable mounting of the sliding pin, that the guide channel in one vertical surface has an inner wall contour and an outer wall contour for guiding the sliding pin in a circumferential trajectory with at least two characteristic points: the upper locking point at which the quill, guided by the sliding pin, can be locked in the release position at least by gravity, and a lower locking point , where the at least gravity-driven movement of the quill in the clamping position is limited downwards.

The guide channel advantageously also has a reversal point between the upper latching point and the lower latching point, at which the release position of the quill with the sliding pin can be taken again in the upper latching point after leaving the upper latching point without approaching the lower latching point, which results in a trajectory with a shortened vertical latching path r and a free clamping path d up to the lower locking point, whereby the sliding pin can be guided at least on the inner wall contour in the area of the reversal point.

The reversal point in the guide channel is expediently positioned in such a way that the trajectory of the sliding pin from the reversal point to the lower locking point degenerates into a single-track guide channel that releases the vertical free clamping path d. In another variant, the reversal point in the guide channel can be arranged in such a way that the trajectory up to the lower locking point has a V-shaped outer wall contour of the height of the free clamping path d, while the inner wall contour of the guide channel is limited to the height of the locking path r.

In a first embodiment, the means for horizontally movable mounting of the sliding pin is a sliding body, which is preferably guided in a horizontally oriented sliding groove in a vertical surface of the bearing plate, while the guide channel is introduced in a vertical surface of the tailstock. The sliding groove, which is oriented orthogonally to the machine axis and in which the sliding body is guided in a horizontally movable manner for the cantilevered reception of the sliding pin, is expediently arranged opposite the groove-shaped recess for the operative connection with the quick release in the bearing plate.

In a second expedient embodiment, the means for horizontally movable mounting of the sliding pin is a sliding body which is guided in a horizontally oriented sliding groove in a vertical surface of the tailstock, while the guide channel is introduced in a vertical surface of the bearing plate.

In both of the above embodiments, the guide channel can preferably be incorporated into a guide plate which is releasably attached to one of the vertical surfaces in order to be able to replace it if the guide channel wears out.

Furthermore, the quill, which is firmly connected to the bearing plate, is only vertically movable when the sliding pin rotates in the guide channel via a horizontally linearly movable sliding body and can be locked at least by gravity in the upper and lower locking points. But it can also be vertically movable and can be locked in the locking points using spring force.

The quill can preferably be locked in the locking points by gravity, driven by the weight of the quill and bearing plate as well as any additional weights. In addition, the quill can be locked against the tailstock by spring force using retaining springs on the bearing plate.

As a lever mechanism, the quick release expediently contains an actuating lever and a rocker arm guided in parallel via a common pivot bearing with a terminal crank pin, the actuating lever, handle, pivot bearing, rocker arm, crank pin and bearing plate being arranged in the release position within a plane orthogonal to the machine axis. The crank pin on the rocker arm of the quick release is advantageously provided with a roller or ball bearing, the roller or ball bearing being mounted in a rollable manner in the groove-shaped recess of the bearing plate.

Furthermore, the quick release has the handle on the operating lever and is accommodated in the pivot bearing on the tailstock, the handle and the pivot bearing being arranged in parallel opposite each other on both sides of the quill.

The actuating lever and the rocker arm are advantageously rigidly connected to one another in the pivot bearing, with the rocker arm being arranged parallel to the actuating lever. It proves to be advantageous that a vertical adjustment path s of the handle of the operating lever between the release position and the clamping position of the quill is minimized by realizing a minimum vertical dimension of the circumferential guide channel between the stop points and a reversal point. To set a minimum vertical adjustment path s, the actuating lever and the rocker arm preferably have a lever ratio between 1.1: 1 and 1.6: 1.

The invention is based on the basic idea that clamping the rotatable workpieces with a workpiece holder guided on a vertical machine bed is made more difficult by the fact that the quill is freed from the clamping force in the release position, but falls back into its lowest end position due to its own weight and then must be lifted by hand in order to insert the workpiece between a (rotatable) lower and a (vertically movable) upper workpiece holder (tailstock). This is particularly critical if the quill's own weight is to be used to fix the workpiece in the clamping position. The invention solves this problem by bringing the quill into an upper and a lower locking position within the tailstock by means of an additional locking mechanism, these locking positions being realized by means of a lever-operated sliding guide through a sliding pin moved in a closed guide channel.

With the invention it is possible, in a workpiece holder with a vertical rotatable workpiece holder, in particular for optically measuring a rotatable workpiece, to use a quill inserted in a linearly guided tailstock to quickly clamp and unclamp the workpiece between a clamping position and a release position in a simple, easy and simple manner to be operated with one hand.

• 1 eine Prinzipdarstellung einer Messmaschine zum Messen rotierbarer Werkstücke,
• 2 einen prinzipiellen Aufbau eines vertikal verschiebbaren Reitstocks mit einem Schnellspanner und einem Rastmechanismus, bei dem die Rastung in einem am Reitstock integrierten Führungskanal erfolgt, in einer perspektivischen Teilschnittdarstellung,
• 3 einen prinzipiellen Aufbau des Schnellspanners mit Rastmechanismus gemäß 2 in einer perspektivischen Ansicht bei reduziert dargestelltem Reitstock,
• 4 eine erste Ausführungsform eines Führungskanals mit einem in der Rastposition angeordneten Gleitstift,
• 5 eine zweite Ausführungsform eines Führungskanals mit einem in der Umkehrposition angeordneten Gleitstift,
• 6 eine dritte Ausführungsform eines Führungskanals mit reibungsoptimierter Gleitstiftführung,
• 7 eine vierte Ausführungsform eines Führungskanals mit wegoptimierter Gleitstiftführung,
• 8 eine fünfte Ausführungsform eines Führungskanals mit erhöhter Stützkraft der inneren Wandkontur der Gleitstiftführung,
• 9 ein Ausführungsbeispiel des Schnellspanners mit schwerkraftgetriebenen Schnellspanner und
• 10 ein Ausführungsbeispiel eines Reitstocks mit federunterstütztem Schnellspanner.

The invention will be explained in more detail below using exemplary embodiments. In the accompanying drawings show:

• 1 a schematic representation of a measuring machine for measuring rotatable workpieces,
• 2 a basic structure of a vertically movable tailstock with a quick release and a locking mechanism, in which the locking takes place in a guide channel integrated into the tailstock, in a perspective partial sectional view,
• 3 a basic structure of the quick release with locking mechanism 2 in a perspective view with a reduced tailstock,
• 4 a first embodiment of a guide channel with a sliding pin arranged in the latching position,
• 5 a second embodiment of a guide channel with a sliding pin arranged in the reversal position,
• 6 a third embodiment of a guide channel with friction-optimized sliding pin guidance,
• 7 a fourth embodiment of a guide channel with path-optimized sliding pin guidance,
• 8th a fifth embodiment of a guide channel with increased supporting force of the inner wall contour of the sliding pin guide,
• 9 an embodiment of the quick release with gravity-driven quick release and
• 10 an embodiment of a tailstock with a spring-loaded quick release.

The arrangement for clamping a rotatable workpiece 7, as shown in principle 1 is shown, comprises a machine bed 3, on which a workpiece holder 4 with a rotatable workpiece holder 41 and a displaceable tailstock 1 for clamping a workpiece 7. In addition, there is an optical measuring unit 6 which can be moved parallel to a machine axis 43 and which is located on the left and right sides of the workpiece 7 Has light sources and receivers for image recording, which symbolizes the application of the invention in an optical measuring machine.

The tailstock 1 is displaceable on the machine bed 3 along a linear guide 31 and can be temporarily clamped at any position on the linear guide 31 by means of a clamping device 2 in order to be able to accommodate workpieces 7 of different lengths in the workpiece holder 4. It contains a quill 42 for clamping the workpiece 7 along the machine axis 43, which runs between the workpiece holder 41 and the quill 42 and forms the axis of rotation of the workpiece 7.

The tailstock 1 has a quick-release clamp 5 for quickly clamping and unclamping the workpiece 7 in the workpiece holder 4 by axially moving the quill 42 along the machine axis 43. The quick-release clamp 5 has an operative connection to the quill 42, with which the quill 42 is moved along the Machine axis 43 can be moved. For displacement, an actuating lever 51 is arranged on the tailstock 1, with which the quill 42 can be moved between a clamping position that clamps the workpiece 7 and a release position that releases the workpiece 7.

In a preferred exemplary embodiment, the tailstock 1 is slidably received on the linear guide 31 of the machine bed 3 along the vertically oriented machine axis 43 (e.g. that of a measuring machine) and can be clamped at any position on the linear guide 31. The position of the tailstock 1 on the machine bed 3 can thus be adapted to the length of the rotatable workpiece 7 to be picked up vertically on the machine axis 43. To adapt to different workpiece lengths, the clamping device 2 of the tailstock 1 is released and the tailstock 1 is moved manually on the handle 11 along the linear guide 31.

The workpiece 7 is clamped between the rotatable workpiece holder 41 and the quill 42 of the tailstock 1. Any form of suitable clamping means can be used on the rotatable workpiece holder 41 for clamping. The quill 42 preferably has a centering tip 423 for clamping.

The quill 42 and the operating lever 51 of the quick release 5 are in 1 shown in the release position. The workpiece 7 is inserted into the arrangement by hand between the centering tip 423 and the workpiece holder 41. For insertion, the tailstock 1 is always clamped to the linear guide 31 in such a way that there is sufficient clear width w between the centering tip 423 and the workpiece holder 41 for unhindered insertion and alignment of the workpiece 7.

For the axial displacement of the quill 42, the tailstock 1 has, as in 2 shown in a partial sectional view, a vertical bushing 421. In the bushing 421, the quill 42 is mounted in a ball bushing 422 in the tailstock 1. The ball bushing 422 enables - e.g. B. in comparison to a plain bearing - a particularly low-friction and smooth movement of the quill 42 without the use of unwanted lubricants. The quill 42 is fastened in the tailstock 1 by means of a cuboid bearing plate 56. In the embodiment selected here, the quill 42 is passed through a hole in the bearing plate 56 and is axially screwed to it.

The quick release 5 is used to axially move the quill 42, as shown in 2 shown in more detail, via the operating lever 51, which is arranged orthogonally to the machine axis 43 and is led out of the tailstock 1 ending with a handle 52. In order to keep the travel s of the actuating lever 51 between the clamping and release positions small, the actuating lever 51 is designed to be as short as possible. Without restricting manual operation, the handle 52 is therefore arranged close to the tailstock 1.

At an end opposite the handle 52, the actuating lever 51 is movably accommodated in the tailstock 1 in an orthogonal pivot bearing 53. The recording on the tailstock 1 takes place in such a way that the handle 52 and the pivot bearing 53 are arranged horizontally opposite one another on both sides of the quill 42. The rotation of the actuating lever 51 in the pivot bearing 53 takes place in an approximately vertical direction because of the relatively large radius between the handle 52 and the pivot bearing 53.

The operative connection between the tailstock 1 and the quill 42 thus consists of the actuating lever 51, which is movably accommodated in the tailstock 1 in an orthogonal pivot bearing 53, a rocker arm 54 with a terminal crank pin 55 (see 3 ) and the bearing plate 56, on which the axially and rotationally roller-mounted quill 42 is axially fixed.

The rocker arm 54 is arranged inside the tailstock 1 parallel to the operating lever 51 located on the outside. It is firmly connected to the actuating lever 51 with a fixed end in the common pivot bearing 53. To minimize the adjustment path s, the length of the rocker arm 54 is as close as possible to the length of the actuating lever 51 to a lever ratio of 1:1. The movement of the actuating lever 51 is thereby limited to a range of single-digit angular degrees.

The crank pin 55 is attached to the free end of the rocker arm 54. The attachment takes place on a side surface of the rocker arm 54 directed towards the bearing plate 56, so that the crank pin 55 can engage in an opposite lateral recess 561 in the bearing plate 56. When a movement is carried out with the actuating lever 51, the quill 42 is carried along with the rocker arm 54 via the crank pin 55 engaging in the bearing plate 56, ie raised or lowered. The height of the side recess 561 allows a largely play-free movement of the crank pin 55. The horizontal length of the recess 561 enables compensation for different path lengths that arise when the rotational movement of the rocker arm 54 about the pivot bearing 53 is converted into the linear displacement of the quill 42. If a ball bearing 551 is placed on the crank pin 55, like the one in 3 As shown, the active connection is designed to be particularly smooth and wear-resistant.

In the release position, the quill 42 is retracted into the tailstock 1. To lock the quill 42 in the release position, the quick release 5 has according to 3 via a guide plate 57, into which a guide channel 58 is introduced, in which a sliding pin 566 fastened in a sliding body 565 is guided.

The cuboid guide plate 57 is arranged laterally next to the quill 42 and is detachably connected to the tailstock 1. The guide channel 58 is milled into a vertical surface of the guide plate 57 facing the quill 42, the course of the guide channel 58, which is formed by an inner wall contour 581 and an outer wall contour 582, determining the function of the quick release 5. The detachable connection to the tailstock 1 makes it easy to replace the guide plates 57. As a result, different guide plates 57 with different guide channels 58 adapted to the corresponding workpieces 7 can be used.

The sliding pin 566 is guided in the guide channel 58. The sliding pin 566 is firmly connected to the sliding body 565, in which it is cantilevered on one side. The projecting part of the sliding pin 566 engages in the guide channel 58.

The sliding body 565 is accommodated in the bearing plate 56. To accommodate the sliding body 565, a linear horizontal sliding groove 562 is arranged on a side surface of the bearing plate 56 opposite the guide channel 58. In the sliding groove 562, the sliding body 565 is horizontally movable together with the sliding pin 566, so that it can move relative to the fixed guide plate 57. In order to ensure a parallel alignment of the side surface of the bearing plate 56 to the guide plate 57 with the guide channel 58, the bearing plate 56 is attached to two guide bolts 563 (see 2 , 9 and 10 ) guided. The guide bolts 563 are guided through the bearing plate 56 parallel to the axis of the quill 42. This prevents the bearing plate 56 from rotating together with the quill 42 around the machine axis 43.

An in 4 The first exemplary embodiment of the guide channel 58 shown has, in rough approximation, a heart-shaped course, with the guide channel 58 being divided into several successive sections. The sections are symbolized by arrows that indicate the direction of movement of the sliding pin 566. The guide channel 58 has such a width over large parts of its circumferential path that the sliding pin 566 in the guide channel 58 can be freely engaged and guided on both sides.

In 4 the guide channel 58 and the sliding pin 566 are shown with a solid line. The bearing plate 56, the sliding body 565 guided in the sliding groove 562 and various imaginary positions of the sliding pin 566 in the guide channel 58 are shown with broken lines. In the release position the quill 42, the sliding pin 566 is located in an upper locking point 584. The upper locking point 584 is arranged in the upper course of the guide channel 58 and is formed by the inner wall contour 581. In the upper locking point 584, the sliding pin 566 is locked by the gravity of the quill 42. When moving the quill 42, the sliding pin 566 can be placed at the upper locking point 584 or moved out of the upper locking point 584. The movement of the sliding pin 566 is determined by the course of the guide channel 58. For the quick release 5 to function, it is necessary that the sliding pin 566 completely passes through the guide channel 58 once after leaving the upper locking point 584 before it can be placed again at the upper locking point 584.

To describe the guide channel 58 in 4 To simplify, a vertical center line 583 should be introduced through the upper locking point 584 at this point.

Starting from the upper locking point 584, the guide channel 58 initially runs vertically upwards. When the quill 42 is moved upwards against gravity, the sliding pin 566 is lifted out of the upper locking point 584 along the center line 583.

The sliding pin 566 then continues to move upwards in the guide channel 58 along an outer wall contour 582 that rises at approximately 45°, moving away from the center line 583. The rising course ends at the top of the outer wall contour 582 in a first stop point 586, in which the vertical displacement of the quill 42 is limited upwards. Until the first stop point 586 is reached, the sliding pin 566 is moved away from the center line 583 through the guide channel 58. The horizontally movable sliding body 565 shifts in the sliding groove 562 of the bearing plate 56.

Starting from the first stop point 586, the guide channel 58 initially runs vertically downwards. With the downward movement following the first stop point 586, the quill 42 is moved in the direction of the clamping position. The essentially vertical guide channel 58 is guided further downwards and back to the center line 583 through an outer wall contour 582 angled at approximately 45° and crosses it. Beyond the center line 583, the sliding pin 566 in the guide channel 58 moves further away from the center line 583 at the same angle until it arrives at a reversal point 588.

At the reversal point 588, the guide channel 58 divides vertically up and down. The part of the guide channel 58 that runs vertically downwards from the reversal point 588 ends in a lower locking point 585 formed by the outer wall contour 582. The lower locking point 585 is the lowest point in the course of the guide channel 58 and limits the downward displacement of the quill 42.

The reversal point 588 is defined by a deepest point of the inner wall contour 581. When moving the quill 42 from the release position into the clamping position and back into the release position, the sliding pin 566, starting from the upper locking point 584, completely circles the inner wall contour 581. In order to return to the upper locking point 584, the sliding pin 566 must at least pass the reversal point 588 . Only after the reversal point 588 can the upper locking point 584 be reached again with the sliding pin 566. A vertical locking path r between the first stop point 586 and the reversal point 588 determines the minimum required adjustment path s, which must be covered in order to repeatedly assume the release position with the quick release 5. The smaller the detent path r, the smaller the required adjustment path s on the actuating lever 51 and the sooner it is possible to return to the release position after leaving the release position without first moving the quill 42 completely to the lower detent point 585 (without the workpiece 7 clamped ) or into the clamping position (with the workpiece 7 clamped).

The lower locking point 585 and the first stop point 586 define a maximum displacement path v over which the quill 42 can be moved with the quick release 5 in the vertical direction. A free clamping path d is formed between the reversal point 588 and the lower locking point 585. The free clamping path d makes it possible to clamp workpieces 7 whose lengths vary in the area of the free clamping path d while the position of the tailstock 1 clamped to the linear guide 31 remains unchanged.

The lower locking point 585 is only reached by the sliding pin 566 if no workpiece 7 is clamped in the workpiece holder 4. When clamping a workpiece 7, the downward movement of the sliding pin 566 ends before reaching the lower locking point 585, since the quill 42 first touches the workpiece 7 with the centering tip 423. The quill 42 is then in the clamping position in which it rests on the workpiece 7 with its gravity. In the clamping position, the workpiece 7 is centered on the machine axis 43 with the centering tip 423 and clamped with the weight of the quill 42.

The part of the guide channel 58 that runs vertically upwards from the reversal point 588 leads back to the upper resting point 584. When the quill 42 is moved upwards from the lower locking point 585, from the reversal point 588 or from any position in between (e.g. the clamping position), the sliding pin 566 is initially also moved vertically upwards. In the upper course of the guide channel 58, the sliding pin 566 changes its direction again and runs again towards the center line 583 at an approximately 45 ° angle of the outer wall contour 582. The upward course ends above the upper locking point 584 at a second stop point 587 in the outer wall contour 582. The second stop point 587 is arranged before reaching the center line 583 and limits the vertical upward displacement of the quill 42 via the sliding pin 566.

From the second stop point 587, the guide channel 58 runs vertically downwards. With the downward displacement of the quill 42 following the second stop point 587, the sliding pin 566 is moved back into the upper locking point 584. For this purpose, the inner wall contour 581, which is vertically opposite the second stop point 587, has an angle of approximately 45° downwards. The inner wall contour 581 leads directly back to the upper locking point 584 on the center line 583.

One in 5 The second embodiment of a guide channel 58 shown differs from that in the position of the reversal point 588 4 shown embodiment variant. The reversal point 588 is shifted upwards here. For this purpose, the inner wall contour 581 leads upwards at an angle of approximately 45° after the guide channel 58 has crossed the center line 583. If the quill 42 moves downwards following the first stop point 586, the upper locking point 584 can be reached again after the sliding pin 566 has passed the center line 583. As a result, with the same displacement path v, a reduction in the locking path r is achieved while at the same time increasing the free clamping path d.

$${\mathrm{\mu }}_{\text{G}}={\text{F}}_{\text{N}}/{\text{F}}_{\text{R}}$$

wobei F_R eine Reibkraft zwischen den Materialien der Führungsplatte 57 und des Gleitstifts 566, F_N eine Normalkraft senkrecht zu den geneigten Flächen der Wandkonturen 581 und 582 und µ_G die von der Materialpaarung abhängige Gleitreibungszahl ist. Solange die Bedingung $$\mathrm{\alpha }>\text{arctan }{\mathrm{\mu }}_{\text{G}}$$

erfüllt wird, ist ein ungehindertes Gleiten gewährleistet. Bei einer häufig verwendeten Reibpaarung Stahl/Stahl (geölt) ist µ_G = 0,12, sodass sich die vorstehende Bedingung bis zu einem minimalen Neigungswinkel α = 6,9 ° erfüllt und somit der Gleitzustand für alle Neigungswinkel α > 6,9 ° gegeben ist. Für eine Reibpaarung Stahl/POM (Polyoxymethylen), bei der ein Gleitstift 566 aus Stahl in einem POM-Kanal gleitet, sind sogar noch kleinere Neigungswinkel α zulässig.Furthermore, the detent path r can be reduced by reducing a horizontal inclination angle α of non-vertical surfaces of the inner and outer wall contours 581, 582. This increases - with a fixed displacement path v - the free clamping path d of the quill 42. However, the inclination defined in this way can only be reduced as long as the friction angle ρ with which the sliding pin 566 hits the inclination does not become too large. A friction angle ρ that is too large prevents the sliding pin 566 from sliding freely on the wall contours 581 and 582. The friction angle ρ depends on the material and follows the formula $$\text{tan}\mathrm{\rho }={\text{F}}_{\text{R}}/{\text{F}}_{\text{N}},$$

$${\mathrm{\mu }}_{\text{G}}={\text{F}}_{\text{N}}/{\text{F}}_{\text{R}}$$

where F _R is a frictional force between the materials of the guide plate 57 and the sliding pin 566, F _N is a normal force perpendicular to the inclined surfaces of the wall contours 581 and 582 and _μG is the coefficient of sliding friction dependent on the material pairing. As long as the condition $$\mathrm{\alpha }>\text{arctan}{\mathrm{\mu }}_{\text{G}}$$

is met, unhindered sliding is guaranteed. For a frequently used steel/steel (oiled) friction pairing, µ _G = 0.12, so that the above condition is fulfilled up to a minimum inclination angle α = 6.9 ° and thus the sliding condition is given for all inclination angles α > 6.9 ° is. For a steel/POM (polyoxymethylene) friction pairing, in which a sliding pin 566 made of steel slides in a POM channel, even smaller inclination angles α are permissible.

The aim is to make the free clamping path d as large as possible so that the locking is secured when actuating from the clamping position to the release position, even with the workpiece 7 set, which reduces the free clamping path d.

In 6 a third embodiment of the guide channel 58 is shown, which adheres to the known heart shape for both the inner wall contour 581 and the outer wall contour 582. The inner wall contour 581 determining the rest path r is designed approximately symmetrically. The outer wall contour 582, which determines the free clamping path d, is designed to be asymmetrically and extended downwards in a V-shape compared to the inner wall contour 581. This is compared to the exemplary embodiments 4 and 5 , at the outer wall contour 582 leading from the first stop point 586 to the lower locking point 585, a flatter angle to the center line 583 is achieved, so that less wear is achieved.

In 7 and 8th Further possible variants of the guide channel 58 are shown, which deviate from the heart shape. The upper locking point 584, the stop points 586 and 587 and the reversal point 588 are positioned differently here, so that certain requirements are taken into account, but disadvantages have to be accepted for other parameters.

In 7 is opposite 4 until 6 Between the reversal point 588 and the second stop point 587, a path shortening has been made, which makes it possible to place the upper locking point 584 - deviating from the heart curve shape - outwards, as a result of which the upper locking point 584 is supported underneath by a larger volume of material. The larger volume of material increases compared to the smaller volume of material inside the inner wall contour 581 4 until 6 , the stability (lower risk of breakage) of the guide channel 58. There is also the advantage that the rest distance r is also kept small.

In 8th is opposite 7 The path optimization to reduce the rest path r has been omitted in order to increase the supporting material volume on the inner wall contour 581. This plays a role in particular if the guide plate 57 is made of plastic instead of steel or other metals - for reasons of easier production of the guide channel 58 - such as. B. POM is used.

In another embodiment of the quick release 5 according to 9 the guide plate 57 is fastened with the guide channel 58 to the bearing plate 56 of the quill 42. The sliding pin 566 engaging in the guide channel 58 is mounted with the sliding body 565 in a horizontally arranged sliding groove 562 attached to the tailstock 1. When the quill 42 is axially displaced with the quick release 5, the guide plate 57 is moved vertically with the quill 42 and the sliding pin 566, which can be moved horizontally in the sliding groove 562 with the sliding body 565, is moved through the guide channel 58. The functions of the guide channel 58 correspond to the exemplary embodiments described so far.

In another, in 10 In the exemplary embodiment shown, tension springs 564 are accommodated on the guide pins 563. The tension springs 564 are arranged between the bearing plate 56 and the heads of the guide bolts 563 and generate a tension force that is available in addition to the gravity of the quill 42 for clamping the workpiece 7. To increase the gravity, it is of course also possible to attach additional weights (not shown) to the quill 42.

Reference symbol list

1

Tailstock

11

Handle

2

Clamping device

3

Machine bed

31

Linear guide

4

Workpiece holder

41

Workpiece holder

42

Quill

421

liner

422

Ball bushing

423

center point

43

Machine axis

5

Quick release

51

Operating lever

52

handle

53

Pivot bearing

54

rocker arm

55

Crank pin

551

ball-bearing

56

bearing plate

561

(groove-shaped) recess

562

sliding groove

563

Guide pin

564

tension spring

565

Sliding body

566

Sliding pin

57

Guide plate

58

Guide channel

581

inner wall contour

582

outer wall contour

583

Centerline

584

upper locking point

585

lower rest point

586

first stopping point

587

second stopping point

588

turning point

6

optical measuring unit

7

workpiece

d

free clamping path

r

rest stop

s

(vertical) travel (of the actuating lever 51)

v

Displacement path (of the quill 42)

w

Clear width (of the workpiece holder 4 in the release position)

α

Angle of inclination

ρ

Friction angle

FN

Normal force

FR

friction force

Claims (15)

Arrangement for clamping a rotatable workpiece, containing a workpiece holder (4) with a rotatable workpiece holder (41) and a quill (42) opposite on a machine bed (3) for clamping the workpiece (7) on a between the workpiece holder (41) and the Machine axis (43) running on the quill (42), the quill (42) having an operative connection to a quick-release clamp (5) in a tailstock (1) which can be moved and clamped on a linear guide (31), with which the quill (42) is moved along the quill (42). The machine axis (43) can be moved between a clamping position and a release position of the workpiece (7), characterized in that - the quill (42) is accommodated in the tailstock (1) so that it can roll along the machine axis (43), - the quill (42) has a bearing plate (56) orthogonal to the machine axis (43) for establishing the operative connection to the quick release (5), and the quick release (5) contains a lever mechanism (51, 52, 53, 54) on which a terminal crank pin (55) is inserted a lateral groove-shaped recess (561) in the bearing plate (56) engages in order to axially displace the quill (42) by means of the lever movement by means of the bearing plate (56), - the tailstock (1) and the bearing plate (56) have adjacent vertical surfaces, one surface of which has a guide channel (58) with at least one upper locking point (584), the guide channel (58) being assigned a horizontally engaging sliding pin (566), and the other surface having a means (565) for horizontally movable mounting of the Sliding pin (566), - the guide channel (58) in one vertical surface has an inner wall contour (581) and an outer wall contour (582) for guiding the sliding pin (566) in a circumferential trajectory with at least two characteristic points: - the upper latching point (584), at which the quill (42), guided by the sliding pin (566), can be locked in the release position at least by gravity, and - a lower latching point (585), at which the movement of the quill (42) is at least gravity-driven. is limited downwards in the clamping position. Arrangement according to Claim 1 , characterized in that the guide channel (58) also has a reversal point (588) between the upper locking point (584) and the lower locking point (585), at which the release position of the quill (42) with the sliding pin (566) after leaving the upper locking point (584) can be taken again in the upper locking point (584) without approaching the lower locking point (585), which results in a trajectory with a shortened vertical locking path r and a free clamping path d to the lower locking point (585), whereby the sliding pin (566 ) can be guided at least on the inner wall contour (581) in the area of the reversal point (588). Arrangement according to Claim 2 , characterized in that the reversal point (588) is attached in the guide channel (58) in such a way that the trajectory of the sliding pin (566) from the reversal point (588) to the lower locking point (585) leads to a single-track guide channel ( 58) is degenerate. Arrangement according to Claim 2 , characterized in that the reversal point (588) is attached in the guide channel (58) in such a way that the trajectory up to the lower locking point (585) has a V-shaped outer wall contour (582) of the height of the free clamping path d, while the inner Wall contour (581) of the guide channel (58) is limited to the height of the locking path r. Arrangement according to Claim 1 , characterized in that the means for horizontally movable mounting of the sliding pin (566) is a sliding body (565) which is guided in a horizontally oriented sliding groove (562) in a vertical surface of the bearing plate (56), while the guide channel (58) is introduced into a vertical surface of the tailstock (1). Arrangement according to Claim 5 , characterized in that the sliding groove (562), which is oriented orthogonally to the machine axis (43), in which the sliding body (565) is guided to be horizontally movable for the cantilevered reception of the sliding pin (566), opposite the groove-shaped recess (561) for the operative connection the quick release (5) is arranged in the bearing plate (56). Arrangement according to Claim 1 , characterized in that the means for horizontally movable mounting of the sliding pin (566) is a sliding body (565) which is guided in a horizontally oriented sliding groove (562) in a vertical surface of the tailstock (1), while the guide channel (58) is incorporated into a vertical surface of the bearing plate (56). Arrangement according to Claim 1 , characterized in that the quill (42), which is firmly connected to the bearing plate (56), is only vertically movable and in the upper and lower locking points when the sliding pin (566) rotates in the guide channel (58) via a horizontally linearly movable sliding body (565). (584, 585) can be locked at least by gravity. Arrangement according to Claim 8 , characterized in that the quill (42) can be locked in the locking points (584, 585) by gravity by the weight of the quill (42) and bearing plate (56) as well as additional weights. Arrangement according to Claim 9 , characterized in that the quill (42) is vertically movable and can be locked in the locking points (584, 585) by spring force. Arrangement according to Claim 1 , characterized in that the quick release (5) contains an actuating lever (51) and a rocker arm (54) guided in parallel via a common pivot bearing (53) with a terminal crank pin (55) and with an actuating lever (51), handle (52), Pivot bearing (53), rocker arm (54), crank pin (55) and bearing plate (56) is arranged in the release position within a plane orthogonal to the machine axis (43). Arrangement according to Claim 1 or 11 , characterized in that the crank pin (55) of the quick release (5) is provided with a rolling or ball bearing (551), the rolling or ball bearing (551) engaging in a rollable manner in the groove-shaped recess (561) of the bearing plate (56). is appropriate. Arrangement according to Claim 11 , characterized in that the quick release (5) has the handle (52) on the operating lever (51) and is received in the pivot bearing (53) on the tailstock (1), the handle (52) and the pivot bearing (53) being parallel and opposite each other are arranged on both sides of the quill (42). Arrangement according to Claim 11 , characterized in that the actuating lever (51) and the rocker arm (54) are rigidly connected to one another in the pivot bearing (53) and the rocker arm (54) is arranged parallel to the actuating lever (51). Arrangement according to Claim 11 , characterized in that a vertical adjustment path s of the handle (52) of the actuating lever (51) between the release position and the clamping position of the quill (42) is minimized by a minimum vertical dimension of the circumferential guide channel (58) between stop points (586, 587) and a turning point (588).

Images