Clamping chuck

Abstract

The present invention relates to a clamping chuck (1), by which a workpiece (2) is supported individually and centeringly for machining the workpiece by a machine tool, the clamping chuck having a chuck body (3), having four clamping jaws (5, 6, 7, 8) supported radially movably on the chuck body (3), the clamping jaws being arranged in pairs in an X plane or a Y plane, and having a drive piston (9) supported axially movably in the chuck body (3), the drive piston being drive-coupled with the four clamping jaws (5, 6, 7, 8) via inclined surfaces or inclined teeth (10) machined on the drive piston (9) and the corresponding clamping jaws (5, 6, 7, 8), and the four clamping jaws being synchronously fed toward a workpiece (2) to be clamped or moved away from the workpiece.

Description

Technical Field

[0001] The present invention relates to a clamping chuck, by which a workpiece is individually and centrally supported for machining the workpiece by a machine tool, the clamping chuck comprising a chuck body; four clamping pliers supported on the chuck body so as to be radially movable, the clamping pliers being arranged in pairs in an X or Y plane respectively; and a driving piston supported in the chuck body so as to be axially movable, the driving piston being transmission-coupled with the four clamping pliers via inclined surfaces or inclined teeth machined on the driving piston and the corresponding clamping pliers and synchronously feeding the same in the direction of a workpiece to be clamped or moving the same away from the workpiece to be clamped. Background Art

[0002] For example, such a clamping device (known in the technical terminology as a clamping chuck) can be known from DE 102015 204 502 B4. A rocker and a driver are provided between the basic pliers and a mechanically operable drive unit, each of which is connected to one of the rockers in a driving manner. In addition, a coupling ring is arranged in the center of the clamping chuck, and four drivers are arranged on the coupling ring in such a way that there is a movement gap between these components in the radial direction. The coupling ring is supported in the chuck body or housing of the clamping chuck so that it can rotate around the clamping axis. In this case, a radial feed movement of the basic pliers is generated by the rotation of the coupling ring, so that the workpiece is held by the four clamping pliers because they move in the direction of the workpiece and generate a clamping force.

[0003] Because the workpiece is clamped by means of four pairs of diametrically opposed clamping jaws, it exhibits mechanical hyperstatic properties ( ), so a movement gap is provided between the coupling ring and the corresponding driving member. That is to say, when one of the pairs of clamping pliers collides with the workpiece to be clamped earlier, its feed movement is stopped in order to ensure that the clamping pliers extending perpendicularly thereto can cover the distance still existing between the clamping pliers and the surface of the workpiece. The corresponding clamping force should only be generated when all four clamping pliers are in contact with the surface of the workpiece. As a result, the movement gap serves as a balance for the clamping pliers when the clamping pliers move in the direction of the workpiece. In particular, when the workpiece has a rectangular outer contour and its side lengths are dimensioned differently, it is necessary to compensate for this different distance between the pairs of clamping pliers that are completely opposite.

[0004] However, due to the required play between the coupling ring and the driver (which is mechanically coupled to the base jaws or clamping jaws), considerable inaccuracies often occur, so that the positioning of the workpiece is erroneous. This in turn leads to machining errors in the workpiece itself, since the repeatability of the clamping of a large number of identical workpieces cannot be ensured.

[0005] Disadvantageously, however, such movement possibilities are associated with often significant tolerance deviations with respect to the clamping effect, so that the required clamping force cannot be predicted or predetermined exactly.

[0006] That is to say that the movement play existing between the components arranged in the force flow leads to a relative movement between these components. Summary of the invention

[0007] The object of the present invention is therefore to improve a clamping chuck of the type mentioned at the outset in such a way that a positionally accurate, ie centered, alignment is possible for a large number of differently designed workpieces with a high degree of repetition accuracy for the subsequent clamping process.

[0008] The object is achieved according to the invention by the following features, namely, a rocker is arranged between the drive piston and two adjacent clamping jaws, the rocker having a center of symmetry, a pin pivotally supported on the drive piston being inserted into the center of symmetry, the rocker being pivotable about the pin depending on the contact of the clamping jaws on the workpiece, and a transmission pin drivingly coupled to the rocker is arranged laterally adjacent to the pin, the respective clamping jaws bearing and supporting the transmission pin at the end opposite to the rocker, wherein at the ends of the transmission pins A centrifugal force balancing weight is arranged in the chuck body, and the centrifugal force balancing weight is supported in the chuck body in a displaceable manner perpendicular to the feed direction of the drive piston. The centrifugal force balancing weight is transmission-coupled with one of the clamping pliers via a lever, wherein the lever is inclined in the direction of the longitudinal axis of the chuck body during the clamping state of the clamping pliers, and the centrifugal force balancing weight is radially squeezed outward by the rotation of the clamping chuck as follows, so that the radially acting clamping force is transmitted to the corresponding clamping pliers via the centrifugal force balancing weight via the lever.

[0009] Additional advantageous improvements of the present invention are derived from other technical solutions disclosed herein.

[0010] By arranging a rocker between the drive piston and two corresponding adjacent clamping jaws, the rocker having a center of symmetry, a pin supported on the drive piston being inserted into the center of symmetry, the rocker being supported so as to be pivotable around the pin depending on the abutment of the clamping jaws on the workpiece, and a transmission pin being respectively arranged laterally adjacent to the pin, at the opposite ends of the transmission pin the corresponding clamping jaws being supported and supported on the rocker, it is achieved that the distance between two adjacent clamping jaws with respect to the spacing relative to the workpiece is balanced, but no movement play or other uncontrollable deviations are generated in the force flow, thereby ensuring the accurate orientation of the corresponding workpiece to be clamped.

[0011] Because a rocker is inserted between the drive piston and the clamping tongs to be moved, i.e., in the force flow, and the rocker transmits the relative movement of the drive piston directly to the clamping tongs via the transfer pin, a gap-free and balanced clamping of the workpiece is achieved. Here, the clamping tongs that are completely opposite in pairs are assigned to the same length of the workpiece, so that in the case of a rectangular workpiece, one pair of the clamping tongs collides with the workpiece as the first. The further feed movement of these clamping tongs is interrupted, more precisely until the pair of clamping tongs arranged perpendicularly thereto arrives at abutment against the workpiece. Here, the drive piston performs an axial movement, so that the rocker and the transfer pin also move parallel to the longitudinal axis of the chuck body. Here, based on the existing inclined toothing, the drive piston and the clamping tongs, the axial feed movement of the drive piston is converted into a radial feed movement for the clamping tongs.

[0012] It is particularly advantageous if a centrifugal force counterweight is arranged in the chuck body, which is mechanically coupled to a respective one of the clamping jaws via a lever. The lever is supported in the chuck body and, due to the orientation of the lever, a centripetal force is generated during the rotation of the chuck body, which acts on the centrifugal force counterweight, by which the centripetal force is pressed outward. As a result, the lever moves in the direction of the longitudinal axis of the chuck body and generates a radial additional clamping force on the respective clamping jaw. The provided shape of the rocker and the transmission pin does not hinder this additional clamping force increase, because the force flow applied by the drive piston acts directly on the clamping jaw and the centrifugal force counterweight generates an independent clamping force component based on the rotation of the chuck body.

[0013] In order for the movement of the rocker to reach the corresponding transfer pin without tilting or jamming, a guide groove is introduced into the rocker, into which one of the transfer pins can be movably inserted. In this case, the head molded on the corresponding transfer pin has no clearance with respect to the width of the guide groove with respect to the longitudinal axis, so that the two side walls of the head abut against the inner wall of the guide groove, thereby achieving a gap-free force transmission between the rocker and the head of the transfer pin in the direction of movement. When the rocker is deflected to one side, the head moves linearly in the guide groove, because the length of the head is dimensioned smaller than the length of the guide groove; however, at the same time, force transmission in the direction of movement can be achieved, because the deflection of the rocker takes place within a very small measured angle range.

[0014] The suspension of the rockers on the drive piston takes place in their center of symmetry and the guide grooves are dimensioned at the same distance from the center of symmetry so that the deflection of the rockers is identical on all four rockers and is respectively assigned to the clamping jaw which is the first to come into contact with the workpiece to be clamped. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The clamping chuck according to the invention is shown in the drawings and will be described in more detail below. In detail: Figure 1 A top view of a clamping chuck with a chuck body in which four clamping jaws oriented perpendicular to one another are mounted so as to be radially displaceable, by means of which a workpiece of at least partially rectangular design is held centered in space, Figure 2 The diagram of the clamping jaws according to the invention is shown in a perspective view and partially cut away with four centrifugal weights assigned to the respective clamping jaws. Figure 1 a clamping chuck, the centrifugal force counterweight being mechanically coupled to the same via a lever,

[0016] Figure 3 Show according to Figure 1 a drive piston of a clamping chuck with a disassembled clamping jaw and the inclined surfaces required at the clamping jaw for the radial feed of the clamping jaw, and with four rocker arms arranged on the outside of the drive piston, which are drivingly coupled to one of the clamping jaws via a respective transmission pin,

[0017] Figure 4a Show according to Figure 3 The drive piston of the clamping chuck is in the initial state and is shown in section,

[0018] Figure 4b Show according to Figure 4a The drive piston of the clamping chuck is in the deflected position of the rocker,

[0019] Figure 5a Show according to Figure 1 The clamping chuck is shown in an initial state and partially cut away,

[0020] Figure 5b Show according to Figure 1 The clamping chuck is in a position in which two diametrically opposed clamping jaws bear against the workpiece and a clamping jaw extending perpendicular thereto is spaced apart from the workpiece, and

[0021] Figure 5c Show according to Figure 5a Clamping chuck with centrally clamped workpiece. DETAILED DESCRIPTION

[0022] exist Figure 11 shows a clamping chuck 1 by which a partially rectangular workpiece 2 is supported centrally in space for machining by a machine tool (not shown). The clamping chuck 1 consists of a chuck body 3 on which four clamping jaws 5, 6, 7 and 8 are mounted displaceably.

[0023] The clamping jaws 5 and 6 are arranged in the X plane, i.e., completely opposite each other, and the clamping jaws 7 and 8 are arranged in the Y plane extending perpendicularly to the X plane. The four clamping jaws 5, 6, 7 and 8 are radially advanced in the direction of the center of the chuck body 3, i.e., in the direction of the longitudinal axis 4 of the chuck body and in the direction of the workpiece 2. However, if the workpiece 2 to be clamped has a trapezoidal or star-shaped outer contour, the clamping jaws 5, 6, 7, 8 can be arranged in any position, so that although one of the x or y planes extends through two of the four clamping jaws 5, 6 or 7, 8, these planes are not oriented perpendicularly to each other.

[0024] If the workpiece 2 has different edge lengths or other different outer contours (which is schematically indicated by ΔS1 and ΔS2), the pairs of clamping jaws 5, 6 or 7, 8 collide with the surface of the workpiece 2 at different time intervals. This results in different collision times in time if the spacing ΔS1 between the clamping jaws 5, 6 or 7, 8 is greater than the spacing ΔS2. However, the four clamping jaws 5, 6, 7 and 8 are moved synchronously by means of the drive piston 9, so that this spatial or temporal offset is compensated.

[0025] Furthermore, it is problematic to position the workpiece 2 manually or mechanically in exact alignment with respect to the longitudinal axis 4. As a result, the center of symmetry of the workpiece 2 is often not aligned with respect to the longitudinal axis 4 of the chuck body 3. By advancing the clamping jaws 5, 6, 7 and 8, the problem should be eliminated not only in the X plane but also in the Y plane in that the existing distance differences are compensated by shifting the workpiece 2. This is achieved in that the clamping jaws 5, 6 or 7, 8, which are completely opposite in pairs, shift the workpiece 2 in the X plane and / or the Y plane in order to orient the center of symmetry of the workpiece 2 in alignment with respect to the longitudinal axis 4 of the chuck body 3. As soon as the workpiece 2 is clamped between two opposite clamping jaws 5, 6 or 7, 8, the workpiece is positioned in the corresponding X plane or Y plane.

[0026] However, when the clamping jaws 5, 6, 7 and 8 are moved synchronously by the drive piston 9, the time differences between the impact of the clamping jaws 5, 6, 7 and 8 with the workpiece 2 must be balanced. The time or geometric balance can be determined by Figures 2 to 5c Learn in detail.

[0027] Depend on Figure 2 It turns out that the drive piston 9 has an inclined toothing 10 which interacts with the inclined toothing 10 machined on the clamping jaws 5, 6, 7 and 8. That is, when the drive piston 9 moves away from the workpiece 2 to be clamped and the drive piston 9 is pressed between the clamping jaws 5, 6, 7 and 8 against the inclined toothing 10 of the clamping jaws, the force transmission displaces the clamping jaws 5, 6, 7, 8 radially in the direction of the longitudinal axis 4, that is, in the direction of the workpiece 2.

[0028] Furthermore, a centrifugal force counterweight 19 is displaceably supported in the chuck body 3 and is respectively coupled to one of the clamping jaws 5, 6, 7 or 8 via a lever 20. The lever 20 is pivotally supported in the chuck body 3. Figure 2 The initial position depicted in FIG. 1 shows that the centrifugal weight 19 is arranged relatively close to the longitudinal axis 4 and that the lever 20 therefore extends outwardly at an angle in the direction of the workpiece 2 to be clamped. However, as soon as the chuck body 3 is set in rotation, the centrifugal weight 19 is pressed outwardly due to the centripetal force acting on it, so that the distance between the centrifugal weight 19 and the longitudinal axis 4 increases. As a result, the free end of the lever 20 assigned to the centrifugal weight 19 also moves away from the longitudinal axis 4, and the free end of the lever 20 assigned to the respective clamping jaw 5, 6, 7 or 8 moves in the direction of the longitudinal axis 4, thereby generating an additional clamping force for fixing the workpiece 2.

[0029] Depend on Figure 3 It can be seen that the drive piston 9 contains four free spaces 23, in which four rockers 11 are inserted or arranged, the rockers having a center of symmetry 12. The center of symmetry 12 contains a receiving opening, into which a pin 13 engages. The pin 13 is supported on the drive piston 9. In addition, the rockers 11 are supported on the pins 13 so that they can pivot.

[0030] Two guide grooves 16 are formed in the rocker 11 laterally beside the pin 13, which are oriented perpendicularly to the longitudinal axis 4 in the unactuated state of the rocker 11. This means that the rocker 11 is not deflected in the unactuated state, but rather extends perpendicularly to the longitudinal axis 4.

[0031] Depend on Figure 4a and 4b The actuation of the rocker 11 and the transmission of force between the rocker and the corresponding clamping jaws 5, 6, 7 or 8 can be seen. That is, the first and second transmission pins 14 and 15 are inserted into the corresponding guide grooves 16. Here, the first transmission pin 14 is assigned to the clamping jaws 5 and 6 and the second transmission pin 15 is assigned to the clamping jaws 7 and 8 and is respectively coupled thereto in a driving manner.

[0032] Furthermore, a head 17 is provided at each free end of the transmission pins 14 and 15 assigned to the rocker 11, which head can be inserted into the corresponding guide groove 16 in a linearly displaceable manner. Here, the outer contour of the head 17 is matched to the inner contour of the guide groove 16 in such a way that the end side extending in the direction of the longitudinal axis 4 abuts against the inner wall of the guide groove 16 and a free space or gap exists between the end sides of the head 17 extending perpendicularly to the longitudinal axis 4. Thus, more precisely, when the rocker 11 moves around the pin 13 into one of the two possible deflections, the head 17 can move relative to the guide groove 16 perpendicularly to the longitudinal axis 4. According to Figure 4b , that is, the clamping jaws 7 are the first to come into contact with the workpiece 2, so that the clamping jaws 5 have to move further in the direction of the workpiece 2. The rocker 11 therefore compensates for this feed difference between the two pairs of clamping jaws 7 and 8 on the one hand and clamping jaws 5 and 6 on the other hand by the deflection α shown. The drive piston 9 is pulled away from the workpiece 2 to be clamped, so that the clamping jaws 7 and 8 that are already resting on the workpiece 2 can remain in their position and the difference ΔS2 minus ΔS1 can be compensated by the pivoting of the rocker 11.

[0033] Furthermore, a transmission wedge 22 is arranged in each of the four free spaces 23 as a distance overlap between the rocker 11 and the respective clamping jaw 5, 6, 7 or 8. The respective transmission wedge 22 contains a through-opening 24 through which the respective transmission pin 14, 15 passes or through which the transmission pin protrudes.

[0034] The transmission wedge 22 serves as a buffer or force transmitter between the rocker 11 and the clamping jaws 5 , 6 , 7 or 8 and is mounted displaceably in the chuck body 3 so as to be linearly movable.

[0035] exist Figure 5a , 5b This movement process is described in detail in FIG. 5c with respect to different operating or clamping states of the clamping chuck 1. Figure 5a It can be seen that the clamping jaws 5, 6, 7 and 8 are spaced at different distances from the workpiece to be clamped. This is therefore the starting position of the clamping chuck 1. As soon as an actuating force acts on the drive piston 9, this force is transmitted via the pin 13 to the rocker 11 and via the two transmission pins 14 and 15 to the respective clamping jaw 5, 6, 7 or 8. The linear return movement of the drive piston 9 is converted into a radial feed movement of the clamping jaws 5, 6, 7 and 8 by the existing inclined toothing 10, so that the clamping jaws can be moved toward the workpiece 2 to be clamped.

[0036] exist Figure 5b , it is shown that the diametrically opposed clamping jaws 7 and 8 first come into contact with the workpiece 2 and are thereby oriented in the Y plane relative to the longitudinal axis 4. In this position of the clamping jaws 5 and 6, the rocker 11 has not yet been actuated.

[0037] exist Figure 5c 2 shows how the difference between the clamping jaws 5 and 6 relative to the workpiece 2 is bridged or compensated by the deflection α of the rocker 11. The drive piston 9 is moved further in the actuation direction and the clamping jaws 7 and 8 are held in their respective positions by the pivoting of the rocker 11. Figure 5b , and only the clamping jaws 5 and 6 arranged perpendicular thereto are advanced further until they come into contact with the workpiece 2 .

[0038] As soon as all four clamping jaws 5, 6 or 7 and 8 have reached their resting position on the workpiece 2, the drive piston 9 generates the actual clamping force. The more the drive piston is driven, the higher the clamping force generated. The different arrangements of the rocker 11 and the transmission pins 14, 15 are thus not changed, so that they remain in the equilibrium position assumed.

[0039] Thus, by means of the clamping chuck 1 according to the invention, a workpiece 2 can be held centered in space and supported for machining thereof by a machine tool, the workpiece having an arbitrary outer contour, since the inner contours of the clamping jaws 5, 6, 7, 8 are adapted to the outer contours of the differently designed workpiece 2 and can partially surround the workpiece.

Claims

1. A clamping chuck (1) by means of which a workpiece (2) is supported individually and centrally for machining the workpiece by a machine tool, - having a chuck body (3), - having four clamping jaws (5, 6, 7, 8) mounted on the chuck body (3) so as to be radially movable, the clamping jaws being arranged in pairs in each case in the X or Y plane, - and having an axially movably supported drive piston (9) in the chuck body (3), the drive piston being drive-coupled to the four clamping jaws (5, 6, 7, 8) via inclined surfaces or inclined teeth (10) machined on the drive piston (9) and the corresponding clamping jaws (5, 6, 7, 8) and synchronously advancing the same in the direction of a workpiece (2) to be clamped or moving it away from the workpiece to be clamped, It is characterized in that - a rocker (11) is arranged between the drive piston (9) and two adjacent clamping jaws (5, 7 or 6, 8), the rocker (11) has a center of symmetry (12), into which a pin (13) is inserted, which is pivotably mounted on the drive piston (9), and about which the rocker (11) can be pivoted, depending on the contact of the clamping jaws (5, 6 or 7, 8) on the workpiece (2), - and laterally adjacent to the pin (13) there are respectively provided transfer pins (14, 15) drivingly coupled to the rocker (11), the respective clamping jaws (5, 6, 7 or 8) being supported and braced at the ends of the transfer pins opposite the rocker (11), A centrifugal force counterweight (19) is arranged in the chuck body (3), the centrifugal force counterweight (19) is supported in the chuck body (3) in a displaceable manner perpendicular to the feed direction of the drive piston (9), and the centrifugal force counterweight (19) is transmission-coupled to one of the clamping jaws (5, 6, 7 or 8) via a lever (20). The lever (20) is inclined in the direction of the longitudinal axis (4) of the chuck body (3) during the clamping state of the clamping jaws (5, 6, 7, 8), and the centrifugal force counterweight (19) is pressed radially outward by the rotation of the clamping chuck (1) in such a way that a radially acting clamping force is transmitted to the corresponding clamping jaws (5, 6, 7, 8) via the centrifugal force counterweight (19) via the lever (20).

2. The clamping chuck according to claim 1, It is characterized in that The tilting of the rocker (11) results in a feed compensation for one of the two pairs of clamping jaws (5, 6 or 7, 8), which move in a common X or Y plane.

3. The clamping chuck according to claim 1 or 2, It is characterized in that Two guide grooves (16) are incorporated into the rocker (11), into which a respective one of the transfer pins (14 or 15) can be inserted with a slight linear movement.

4. The clamping chuck according to claim 3, It is characterized in that A head (17) is formed on each transmission pin (14, 15), which engages in one of the guide grooves (16) of the rocker (11), and an outer edge of the head (17) extending perpendicularly to the feed movement of the rocker (11) or the drive piston (9) is dimensioned to be smaller than the length of the guide groove (16).

5. The clamping chuck according to claim 4, It is characterized in that The head (17) bears against two opposite inner walls (18) of the guide groove (16) with respect to the advancing direction of the rocker (11) and can be acted upon by the inner walls with an advancing force.

6. The clamping chuck according to claim 1 or 2, It is characterized in that The distances of the two transfer pins (14, 15) from a pin (13) arranged in the center of symmetry (12) of the rocker (11) are dimensioned to be identical.

7. The clamping chuck according to claim 1 or 2, It is characterized in that Two transmission pins (14, 15) fixed to a rocker (11) extend in parallel and are supported displaceably in the drive piston (9).

8. The clamping chuck according to claim 1 or 2, It is characterized in that The outer contour of the workpiece (2) to be clamped has any outer shape, and the clamping jaws (5, 6, 7, 8) are adapted to the existing outer contour of the workpiece (2) and partially surround the outer contour.

9. The clamping chuck according to claim 3, characterized in that A respective one of the transfer pins (14 or 15) is inserted into the guide groove perpendicularly to the longitudinal axis (4) of the chuck body (3).

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