Ball clamping device

Abstract

The present invention relates to a ball clamp which is fixable to a machine bed for releasably clamping a workpiece, the shaft passing through which is kept connected to the workpiece via attachment means, while a clamping joint constituted by a ball socket and a ball clamp receiving the shaft can be selectively locked or unlocked, thereby allowing relative movement of the workpiece in the unlocked state and subsequent clamping thereof to allow fixing in a newly occupied position.

Description

[Technical Field]

[0001] The present invention relates to a ball clamp for releasably clamping a workpiece. [Background technology]

[0002] It is often necessary to process a workpiece so that it meets a predetermined target dimension. For this purpose, it is often clamped, for example, in a machine bed, using a clamping device. Residual stresses may be generated in the workpiece during processing, and attempts may then be made to deform the clamped workpiece to compensate for these residual stresses. This deformation occurs when the clamping device is released, and the deformed workpiece must be re-clamped and re-processed to achieve the target dimension. Re-clamping—especially when multiple clamping devices are used in different areas of the workpiece—is very costly, since the spatial positions of the application points of the clamping devices on the workpiece usually change relative to each other and / or to a constant reference point as a result of the deformation. The clamping devices must then be adjusted accordingly. WO 2021 / 000977 A1 discloses an apparatus and related method for releasably clamping a workpiece. In this apparatus, a spherical multi-component bearing ball, centrally penetrated by a shaft to be clamped, is radially actuated by a pneumatically actuated clamping element to clamp the shaft. However, in the clamped state, the shaft is only insufficiently secured against displacement. Summary of the Invention

[0003] The object of the present invention was therefore to provide a clamping means and a method for using the same that simplifies and speeds up the clamping of the workpiece (again) and takes into account deformation due to residual stresses during processing.

[0004] This problem is solved by the ball clamping device according to claim 1 or by the ball clamping device according to claim 7 The solution is provided by the method according to claim 1. Further preferred embodiments are evident from the dependent claims.

[0005] The present invention is based on the observation that machining of a workpiece can generate residual stresses that cannot be compensated for as long as the workpiece remains clamped after machining (clamped position). After the clamping means is released, the individual workpiece sections rotate and / or slide relative to their previous position until they assume a new position and position in space (compensated position) due to the reduction or compensation of deformation and the resulting stresses. The idea behind the present invention is to carry out this compensating movement from the clamped position to the compensated position when the clamping means is in the released state, so that the workpiece can be subsequently clamped again in the compensated position after the transition to the clamped state, thereby simplifying the clamping operation again.

[0006] The clamping means according to the invention is a ball clamper as defined in claim 1. The ball clamper includes a mounting means that can be coupled to a workpiece, thereby positioning and fixing it relative to the ball clamper. The mounting means is linked to the other components of the ball clamper, and moves relative to these components in the released state, while being immobile in the clamped state. The ball clamper itself can be placed or clamped to the machine bed and remains there without changing position, even when the workpiece deforms to reduce residual stresses and the mounting means perform this relative movement together.

[0007] To this end, the ball clamping device of the present invention comprises an axially configured shaft having an attachment means at one end for connecting the workpiece to be clamped. The ball clamp further comprises a ball clamp that abuts the cylindrical section of the shaft with its inner surface directly or via clamping jaws. With its inner surface facing the shaft, the ball clamp can slide along the cylindrical surface of the shaft, preferably with a small radial clearance. The outer surface of the ball clamp is spherically shaped, centered on an imaginary center point located on the axis of the shaft.

[0008] The ball clamp is surrounded by a ball socket whose (preferably also spherical) inner surface abuts the spherical outer surface of the ball clamp, preferably with a small radial clearance. The spherical inner surface of the ball socket and the spherical outer surface of the ball clamp preferably have the same center of curvature M. The inner surface of the ball socket can slide polyaxially on the spherical outer surface of the ball clamp, thereby allowing any pivotal movement of the ball clamp relative to the ball socket.

[0009] According to the present invention, the ball clamping device, and in particular its ball socket, is movable from a clamped state along or against the clamping direction X to a released state and vice versa, thereby exerting or releasing a clamping force on the ball clamp and shaft. In the released state, the shaft is slidable and preferably rotatable relative to the ball clamp, and the ball clamp can pivot about a center point M relative to the ball socket. In contrast, in the clamped state, the ball socket exerts a radial pressure force on the inner ball clamp, which in turn radially clamps the shaft. Relative movement of the ball socket, ball clamp, and shaft is then no longer possible due to frictional forces generated by the pressure between the clamped components.

[0010] As a result, when in the released state, the shaft can slide along its axis and pivot about its axis, and can also pivot arbitrarily about the center point M. The present invention utilizes this property to enable a compensation movement of the workpiece from the clamping position to the compensation position, during which the workpiece remains connected to the ball clamp via the attachment means. As will be seen later, after assuming the compensation position, the shaft, together with the workpiece to be carried thereby, can be easily and quickly re-fixed by newly generating a clamping force.

[0011] The ball clamp must be designed so that the clamping force exerted on it by the ball socket can be transmitted to the shaft located inside. To this end, each section of the ball clamp must be able to perform a certain, albeit minimal, radial movement in order to be able to securely clamp the shaft. In a particularly simple case, the ball clamp can be designed to have a substantially ball-shaped body with a central through-hole for receiving the shaft, which has at least one circumferential slot that allows elastic deformation of the body in the circumferential and therefore radial directions when pressed with a clamping force on its outer surface.

[0012] Alternatively, the ball clamp preferably includes a plurality of ball clamping members that are partially or completely separated from one another and are preferably evenly spaced around the shaft. Each of these ball clamping members has a cylindrical surface on its inner surface for abutting the shaft, which may also be configured by or with clamping jaws to achieve particularly good clamping action. Each ball clamping member has an outer surface with a spherical surface area that slides along the inner surface of the ball socket and can pivot about a center point M in doing so. The separate or separable individual ball clamping members can be easily replaced, for example for maintenance purposes, and allow easy access to the internally located clamping jaws, if any.

[0013] According to the present invention The ball socket is formed by a plurality of ball-socket members, partially or completely separated from one another and arranged circumferentially around the ball clamp, each of which has a spherically shaped inner surface for abutting against the ball clamp or its respective ball clamping member, and optionally configured with clamping jaws for particularly reliable force transmission. Preferably, each ball-socket member is provided on its outer surface with connecting means for receiving the clamping force applied thereto.

[0014] The clamping force can be applied to the ball socket or its ball socket member, for example, via a pneumatically, hydraulically, or electromechanically operated clamping means. In principle, it may be sufficient to bias the ball socket with a clamping force in only one direction to generate the desired clamping action between the ball socket, the ball clamp, and the shaft, preferably directed toward the shaft axis or center point M.

[0015] One particularly effective alternative, however, is to apply the clamping force radially along the circumference to the ball socket from all sides, so that it is pressed radially inwards over its entire circumference, achieving a uniform clamping action and avoiding lateral displacement of the shaft, especially when biased on only one side. According to the present invention, The ball socket is configured to simultaneously bias the ball clamp above and below the equatorial plane. Because This results in a three-dimensional bias or deformation of the ball socket (and correspondingly of the ball clamp) radially inward towards the shaft. The largest possible contact surface between the ball socket, the ball clamp and the shaft results in a particularly secure locking of these components relative to one another under an appropriate clamping force.

[0016] A particularly preferred embodiment of the ball clamping device includes a clamping means in the form of one, preferably multiple, hydraulically, but preferably pneumatically, operable radial spring for generating the clamping force. To this end, the ball clamping device preferably includes a housing configured substantially rotationally symmetrically about a central axis Z0. The housing is configured to be attached to a machine bed for machining the workpiece held by the ball clamping device. Radial springs are arranged within the housing around the housing axis. Each of these includes a chamber surrounded by a spring element that can be energized by a fluid, particularly compressed air. Under pressure, the chambers expand in a direction parallel to the housing axis, while simultaneously contracting perpendicularly, i.e., radially. This expansion occurs against the inherent spring force of the radial spring, which subsequently attempts to deform the spring back to its initial radially expanded position. Thus, when the pressure is reduced, the radial spring expands again—according to its spring force—in the radial direction. If the radial spring is supported along its outer circumference against the inner wall of the housing, its inner circumference will move toward or away from the central housing axis by a distance dependent on the pressure bias. Depending on the configuration of the radial spring and its spring force, a high radial force can be generated at the inner circumference.

[0017] According to the invention, at least one radial spring is operatively connected to the ball socket at its inner circumference or at a section thereof. In the clamped state, the radial spring generates a radially inward clamping force on the ball socket, which in turn clamps the shaft enclosed by the ball clamp, which is then biased by the ball socket. The frictional force generated by the clamping force between the ball socket, the ball clamp, and the shaft ensures that the shaft is clamped against relative movement with respect to the housing, not only in rotation about the shaft axis, but also in pivoting about a central point and sliding in the direction of the shaft axis. Its position and orientation in space are then fixed. When pressure is applied against it, which results in the radial contraction of the radial spring, and the clamping force is released (released state), the shaft can be freely moved in the aforementioned directions and realigned.

[0018] According to the invention, it is ensured that the shaft is held without clearance when in the clamped state. In particular, even slight movement or clearance along the shaft axis is prevented. Since the ball clamp or its individual components, like the ball socket or its individual ball-socket components, are (slightly) pressed radially inward toward the shaft when clamped and may be slightly deformed in the process, it is ensured that this radial inward movement or deformation results in as little axial clearance as possible between the ball clamp and the ball socket relative to the housing. If such clearance were to occur, the shaft itself, even when clamped, would also have a slight clearance. According to the invention, it is intended that the ball socket acting on the ball clamp be guided along at least one stop surface when moving between the clamped and released states, so that the ball socket cannot deviate perpendicularly to this direction of movement (clamping direction X). Such guides, especially when provided above and below the ball socket, on the one hand prevent deflection (clearance) of the ball socket (including ball clamp and shaft) perpendicular to the clamping direction, and on the other hand, if the ball socket is supported and geometrically held by a stop surface at least on one side, prevent the ball socket from expanding perpendicular to the clamping direction or from flattening in the clamping direction.

[0019] The ball socket or socket member has a spherical inner surface into which the ball clamp or its member engages with its respective outer surfaces (preferably complementary), so that in the clamped state, the ball clamp is also fixed without clearance by the guidance of the clamp socket or its socket member along the stopper surface, and as a result, the shaft itself also has no axial clearance.

[0020] For this guidance, in accordance with the invention, at least one stop surface H is provided for this purpose, along which the ball socket or the individual ball-socket components slide or are guided in the clamping direction X. The stop surface extends in the clamping direction X, preferably in a plane perpendicular to the housing axis Z0. It may be configured as a stop surface on the interior or on the surface of the housing of the ball clamping tool. The stop surface may also be configured as a step or a step surrounding the housing axis Z0 on a substantially rotationally symmetrical housing (in the case of several ball-socket components arranged around the housing axis Z0, each component is assigned its own clamping direction X extending radially inward).

[0021] Preferably, two stop surfaces are provided which are axially opposite one another, in particular which are flat and extend parallel to one another, between which the ball socket or its individual ball socket components are guided radially without clearance. According to the present invention, A plurality of ball-socket members positioned one above the other in the direction of the housing axis Z0 can likewise form stop surfaces H' between them and support or stabilize each other in the axial direction.

[0022] The mounting means arranged on the shaft preferably includes a bearing for accommodating the pivoting movement of the workpiece when it moves from the clamped position to the compensation position relative to the shaft. This is preferably a pure pivoting bearing that does not allow sliding. In particular, this may be a ball joint or a (metal) bellows that acts similarly. One section of the joint is connected to the shaft, while the section that can pivot relative to the shaft is configured for attachment to the workpiece, for example in the form of a fixing pin that can be screwed or otherwise connected to the workpiece.

[0023] This swivel bearing, in combination with a second bearing consisting of a ball socket, a ball clamp, and a shaft slidable therein, allows, in the released state, completely free movement of the workpiece from the clamping position to the compensation position, including subsequent easy fixation. This has the advantage that the laborious and expensive re-clamping of the machined workpiece after deformation, known from the prior art, which often requires the alignment and operation of a large number of individual clamping elements, can be speeded up and automated in this way. This will become particularly clear from the following description of the method according to the invention, which utilizes at least one ball clamp according to the invention.

[0024] In this position, the workpiece to be machined is clamped by the ball clamping device, which is then supported by or tension-locked with the machine bed. The attachment means of the ball clamping device to the shaft are connected to the workpiece and are fixed relative to the machine bed when the ball clamping device is in the clamped position (assuming that the workpiece is supported on the machine bed at at least one other point of application by at least one other ball clamping device or other clamping means, so that pivoting of the workpiece around the attachment means of the ball clamping device to the shaft, which is configured as a pivoting bearing, is also prevented). In this position, the workpiece can initially be clamped and machined without stress, which can generate residual stresses that would deform the workpiece if it were not tension-locked with the ball clamping device in the clamped position. These residual stresses then act on the ball clamping device in addition to any clamping forces that may be present.

[0025] The first method step a) of the present invention aims to transition the ball clamping device from a clamped state to a released state, automatically allowing the workpiece or workpiece area to deform or move from the clamping position provided in the clamped state to a compensating position relative to the corresponding ball clamping device, thereby reducing or eliminating stresses occurring between the workpiece and the ball clamping device. The clamping state can be released, for example, by applying pressure to one or more radial springs, which release the clamping force generated on the ball socket, ball clamp, and shaft in the clamped state by radial contraction. In this state, the shaft, together with the part of the mounting means fixedly connected to it, is freely pivotable and slidable relative to the machine bed. In this way, the part of the mounting means connected to the workpiece, for example, a fixing pin that is not slidable but pivotable relative to the shaft, can achieve the compensating movement of the workpiece from the clamping position to the compensating position, along with any rotational position and position in space. The shaft, which is pivotably and slidably supported in the ball clamping device in the released state, can move relative to the housing of the ball clamping device or relative to the machine bed—in accordance with the movement of the workpiece or the attachment means—to a new position and pivoting orientation, thereby automatically, so to speak, performing the realignment of the clamping means, which in the prior art was carried out manually and at considerable time expense, in order to be able to clamp the deformed workpiece again.

[0026] At most, limitations on such compensating movements are imposed by design constraints, such as the maximum possible swivel angle of the mounting means or ball clamp, or the maximum sliding movement of the shaft along the ball clamp, etc. However, such limitations are rather theoretical, since residual stresses can be reduced by compensating movements that are typically of the order of a few millimeters or tenths of a millimeter—depending on the size of the workpiece.

[0027] According to the invention, the compensation movement can be performed without completely releasing the workpiece from one or more ball clamps. In particular, no access to the machine bed or other manual costs are required to enable the workpiece to be deformed into the compensation position. Instead, this can be achieved simply by the corresponding ball clamps being moved into the release state, which can be triggered, for example, by a pressure application, possibly automated, to a radial spring. This significantly simplifies and speeds up the processing method.

[0028] The method according to the invention can be further enhanced by an additional method step b) following the transition of the workpiece into the compensation position, in which at least one of the previously released ball clamps transitions back into a clamping state, thereby again clamping the workpiece relative to the machine bed in the newly assumed compensation position. This can also be easily automated using the ball clamps according to the invention, for example, by removing the pre-load on the radial springs, which then deform radially toward the shaft and thereby re-secure the shaft through the clamping force acting between the ball socket, the ball clamp, and the shaft. (This also applies if, instead of a radial spring, a different non-manually operated clamping mechanism is used and controlled, hydraulically, electromechanically, or in some other way, to selectively clamp or release the ball socket relative to the ball clamp and shaft.)

[0029] According to another embodiment of the method according to the invention, an additional method step c) comprises machining the workpiece after it has been clamped again in the compensation position, which serves in particular to correct any deformations that may have occurred during the transition to the compensation position and / or to machine the deformed workpiece to the desired dimensions.

[0030] Method steps a) to c) can be repeated multiple times as necessary in order to also reduce residual stresses that are newly generated in the workpiece by subsequent processing.

[0031] A particularly preferred embodiment of the method provides for at least one area of ​​the workpiece to remain connected to the machine bed via a stationary clamping means during method steps a) to c). This at least one area, which remains substantially stationary throughout the method, can serve as a reference point for the subsequent processing steps to be performed on the workpiece after the compensation position has been assumed. Meanwhile, other areas of the workpiece can be removably tension-fixed to the machine bed via the ball clamps according to the invention. When transitioning to the release state, the area of ​​the workpiece held by the respective ball clamps moves relative to the at least one stationary clamped area, which remains unchanged in terms of position.

[0032] The processing of the workpiece may in particular involve cutting, or, additionally or alternatively, the processing may involve welding, gluing, soldering, bending, stamping, punching, hammering, or roll forming.

[0033] In one embodiment, the permanent clamping means for permanently clamping the workpiece to the machine bed can also be a ball clamp according to the invention, which continuously maintains the clamped state during the individual method steps. Alternatively, it can be another clamping means known to those skilled in the art. Preferably, a clamping pot, as described in DE 10 2005 033 468 A1, which is already known from the prior art, is considered.

[0034] Although it is preferable that both the ball socket and the ball clamp have spherical surfaces for their mutual clamping contact, this is not essential. Alternatively, it may be sufficient if only the ball clamp or only the ball socket has a spherical contact surface. In contrast, the other component can slide along the corresponding contact surface and simultaneously pivot about the center point M. For example, instead of a spherical inner surface, the ball socket can have one or more radially deformable annular members, preferably with slits, that tightly surround the ball clamp. The ball clamp with its spherical surface can also penetrate into a circular opening in the inner surface of the ball socket, which has a smaller diameter than the spherical surface. Then, in the clamped state, the opening presses its edge against the ball clamp, thereby clamping it.

[0035] The method can also be implemented with multiple ball clamps holding the workpiece at different areas, which may be necessary, particularly when the workpiece is relatively large. Individual or all of the ball clamps can be selectively moved simultaneously or individually into a clamped or released state, thereby allowing the respective workpiece areas to deform to the compensation position.

[0036] An embodiment of the ball clamping device according to the invention and the implementation of the method according to the invention will now be described in more detail with reference to the example of the drawing, which shows: [Brief explanation of the drawings]

[0037] [Figure 1] 1 is a perspective cross-sectional view showing a ball clamping device according to the present invention. [Figure 2] 2 is a cutaway side view showing the ball clamping device of FIG. 1. [Figure 3] 1 shows the progression of the method according to the invention using a simplified side view of the machine bed. [Figure 4]1 shows the progression of the method according to the invention using a simplified side view of the machine bed. [Figure 5] 1 shows the progression of the method according to the invention using a simplified side view of the machine bed. [Figure 6] 1 shows the progression of the method according to the invention using a simplified side view of the machine bed. DETAILED DESCRIPTION OF THE INVENTION

[0038] The ball clamping device T shown in Figures 1 and 2 comprises a housing G which is configured substantially rotationally symmetrically about a housing axis Z0. By means of clamping means not shown in detail, the housing G can be clamped onto a machine bed E, as can be seen, for example, in Figures 3 to 6.

[0039] Two radial springs F are arranged inside the housing G around the housing axis Z0, positioned one above the other, and their chambers N can be energized by compressed air via a connection not shown in detail. The radial springs F are supported on their outer circumferences radially inwardly by the inner wall I of the housing G. The radial springs F are supported on their inner circumferences by a number of individual ball-socket members P arranged circumferentially around the housing axis. a ,P b ...follows the ball socket P, which is made up of... The radial spring has a maximum radial extension in the unclamped state (no pressure biasing the chamber N) and exerts a clamping force on the radial inner surface of the ball socket member P towards the housing axis Z0. a ,P b ... (clamped condition). When pressure is applied to chamber N, radial spring F expands parallel to housing axis Z0 and simultaneously contracts radially, thereby reducing or eliminating the clamping force on the ball-and-socket member (released condition).

[0040] Ball socket component P a ,Pb ... forms a spherical surface on its inner surface facing the housing axis Z0 for bearing against the ball clamp K, which is in turn formed by individual ball clamp members K1, K2... with spherical outer surfaces arranged around the housing axis. The center of curvature of the spherical inner surface of the ball socket P and the outer surface of the ball clamp K that bears closely against it is the center point M shown in simplified form in Figure 2. The ball socket P and the ball clamp K jointly form a ball joint such that the ball clamp K can pivot relative to the ball socket P and the housing G as long as no clamping force is transmitted between these two components, creating blocking static friction between the ball socket and the ball clamp. a ,P b ... and the ball clamping members K1, K2... are each separated from one another in the circumferential direction by a slit, so that when biased radially by a radial spring, they can each slide slightly toward the center and towards the housing axis Z0.

[0041] The individual ball clamping members, with their inner surfaces facing towards the housing axis Z0, jointly form a substantially cylindrical abutment surface which circumscribes in intimate abutment against a shaft arranged around the shaft axis Z through the centre of the housing G. When in the released state, the ball clamping members do not exert a relative clamping force against the cylindrical surface of the shaft W, which is thereby able to slide in the direction of the shaft axis Z relative to the ball clamping members. Pivotal movement of the shaft W relative to the housing G (or the machine bed E carrying the housing) is also readily possible in the released state. When in the clamped state, the ball-socket member P a ,P b... are pressed radially inward (clamping direction X) against the ball clamping members K1, K2..., which in turn exert a clamping force on the shaft W, thereby fixing it against rotation or sliding relative to the housing G. The clamping direction X is shown in FIG. 2 by the ball-socket member P a 1. Of course, each ball-socket member has its own clamping direction towards the housing axis Z0.

[0042] Ball socket component P a ,P b In order to guide the ball-socket member P without any clearance, two parallel stop surfaces H (see especially FIG. 2) are formed in the housing G, facing each other, between which the ball-socket member P is inserted. a ,P b ... abuts against and is guided radially or supported axially. Both stop surfaces H are formed by rotationally symmetrical supports of the housing that revolve around the housing axis Z0. The stop surfaces H allow the ball-socket member P a ,P b ...does not deviate perpendicularly to the clamping direction X, and the ball-and-socket member P under pressure during clamping a ,P b ... is also prevented by the guide on both sides. a ,P b ... are pressed against the ball clamp K in a form-stable and clearance-free manner. The outer surfaces of the ball clamping members K1, K2..., which are shaped complementarily or form-fittingly to it, rest against the spherical inner surface of the ball-socket member, so that the ball clamping members K1, K2 are also indirectly guided and supported by the stop surface H. The shaft W clamped by the ball clamping members K1, K2 is therefore also fixed clearance-free in the direction of the shaft axis Z or the housing axis Z0.

[0043] Ball-socket members P positioned vertically in the direction of the housing axis Z0 a and P b , which likewise form stop surfaces H' between them, thereby supporting or stabilizing one another in the axial direction.

[0044] At the upper end of the shaft W, mounting means S in the form of a ball joint B are arranged. A lower section of the ball joint B is (preferably detachably) connected to the shaft W. An upper section of the ball joint B carries a fixing bolt R with a thread and a spanner face. The fixing bolt R is connected to the shaft W in a positionally fixed but pivotable manner via the ball joint B. A sliding movement of the fixing bolt relative to the shaft W is therefore not possible, but a pivoting movement is possible therewith. As shown in particular in Figures 3 to 6, the fixing bolt R serves to connect the workpiece U with the shaft W, for example by being screwed into a thread of the workpiece U for which the fixing bolt R is intended.

[0045] In Figure 1, the ball clamp T is shown in the released state. The chamber N of the radial spring F is pressure-biased and expanded, so that no centrally directed clamping force is generated. Accordingly, the shaft W can rotate about the shaft axis Z relative to the housing G, slide along the shaft axis Z, and pivot freely about the center point M, as shown by the double arrow. The shaft axis Z can therefore extend at an angle relative to the housing G and does not have to coincide with the housing axis Z0, although both axes intersect at the center point M.

[0046] In contrast, Figure 2 shows the ball clamping device T in the clamped state. Due to the clamping force realized on the centrally guided shaft W, the degree of freedom shown by the double arrow in Figure 1 is eliminated; instead, the shaft W is rigidly connected to the housing and the machine bed.

[0047] A machining method using a ball clamp according to the invention is shown in a simplified manner in Figures 3 to 6. In Figure 3, a workpiece U is intended for machining and is therefore stress-coupled in one area to the machine bed E via a fixed clamping means L. Such clamping is maintained continuously during the method and serves as a reference or datum point for the individual machining steps.

[0048] The section of the workpiece U that is spaced apart from the clamping means L is screwed in by a fixing bolt R, which is in turn pivotally connected to the shaft W of the ball clamping device T according to the invention. The ball clamping device is clamped to the machine bed E, and its radial spring can be energized by compressed air via a service line (not shown in detail), thereby selectively transferring the ball clamping device T from the clamped state to the released state and vice versa. In the illustrated example, the shaft axis Z coincides for the time being with the housing axis Z0 in order to clearly show the subsequent transition from the clamping position to the compensation position. By unloading the chamber N, the ball clamping device T can be transferred to the clamped state using the spring prestress generated by the radial spring, so that the section of the workpiece U carried by the ball clamping device T is securely clamped and ready for processing.

[0049] In FIG. 4 it can be seen that the workpiece U has been machined by a cutting method on the surface of the machining area D. This machining generates residual stresses which subsequently tend to deform the workpiece U. However, due to the clamping through the ball clamping device T, this deformation is prevented.

[0050] 5 shows the position of the workpiece U after the ball clamping device T has been moved into the release state according to the invention. This releases the clamping of the shaft W and temporarily removes the clamping action of the ball clamping device T on the workpiece U. The workpiece U can then be deformed—according to the residual stresses that have developed—from its previous clamping position into a compensation position, as evidenced by the slight upward curvature of the machining area D. Via the fastening bolt R, this movement is transmitted via the ball joint B to the shaft W, which is then carried out together, so that the shaft W can assume a new position and orientation relative to the housing G. The shaft axis Z and the housing axis Z0 no longer coincide.

[0051] In this new compensation position, the machining no longer corresponds to the target dimensions and re-machining is necessary. For this purpose, the workpiece must be clamped again in a fixed manner in the compensation position so that it can be machined again in the machining area D. According to the invention, this can be done in a simple manner by moving the ball clamping device T from the release position back into the clamping position, so that the shaft W, together with the workpiece area carried by it, is automatically and fixedly fixed in its new position and orientation relative to the housing G or the machine bed E. This has the advantage that no manual intervention is necessary to clamp the workpiece again in the changed position.

[0052] 6, the workpiece can then be reliably machined again, with the reworking in the machining area D achieving the desired dimension. Provided that this reworking no longer generates additional residual stresses, the workpiece can subsequently be released from the fixed clamping means L and ball clamp T without further deformation and the desired desired dimension being maintained. Alternatively, it is also conceivable to first only release the clamping in the ball clamp T (transition to the released state), while inspecting the workpiece U for any possible further deformation or relative movement. If this occurs again, the above-described method steps can be repeated until the desired dimension is within the predetermined tolerance range even in the unclamped state. [Explanation of symbols]

[0053] A Outer surface of ball clamp B Ball joint D Machining area E Machine Bed F Radial spring G Housing H Stopper surface I Housing inner wall K Ball Clamp K1, K2... Ball clamping members L Fixed fastening means M Center point of the spherically curved ball clamp outer surface N Radial spring chamber P ball socket Pa, Pb... Ball-socket components R fixing pin S Mounting means T-ball clamp U workpiece W shaft X clamp direction Z shaft (W) axis Z0 housing axis

Claims

1. A ball clamp (T) for removably clamping a workpiece (U), the ball clamp (T) having a central axis Z ０ and a housing configured around the housing. a) a shaft (W) configured about an axis (Z) having a mounting means (S) at a first end for mounting to a workpiece (U); b) a ball clamp (K) that abuts against the cylindrical section of the shaft (W) via clamp jaws and has an outer surface (A) facing away from the inner surface and shaped like a sphere centered on a central point (M) located on the axis (Z); c) a clamping mechanism is provided having a ball socket (P) whose inner surface abuts against the spherical outer surface (A) of the ball clamp (K); d) The ball socket (P) rotates about the central axis (Z) from a clamped state in which the ball socket (P) applies a clamping force to a spherical outer surface (A) of the ball clamp (K) to a released state in which the clamping force is reduced or eliminated. ０ ) and movable in a radial clamping direction (X) extending perpendicular to the clamping direction (X) and in the opposite direction, e) When the shaft (W) is in a released state, different from when it is in a clamped state, i) slidable in the axial direction of the axis (Z) relative to the ball socket (P) and / or rotatable about the axis (Z); and, ii) capable of pivoting about the central point (M); f) and the ball socket has a spherically shaped inner surface that abuts against the spherical outer surface of the ball clamp (K); g) the ball socket (P) slides along a stopper surface (H) extending along the clamping direction (X) when transitioning between the clamped state and the released state, thereby fixing the ball clamp (K) clamped by the ball socket (P), and together with it the shaft (W), without any clearance, so as not to move perpendicular to the stopper surface (H) when in the clamped state; A ball clamping device, h) the ball socket is aligned with the central axis Z ０ a plurality of ball-socket members (Pa, Pb, ...) positioned one above the other in the direction of i) the ball socket is configured to simultaneously bias the ball clamp above and below an equatorial plane; A ball clamping device characterized by:

2. The ball clamp (K) comprises a plurality of ball clamping members (K1, K2, ...) partially or completely separated from one another and arranged circumferentially around the shaft.

3. 2. The ball clamping device (T) according to claim 1, characterized in that the ball socket (P) can be biased in a direction toward the axis (Z) or the center point (M) by a clamping means that can be operated pneumatically or hydraulically to generate a clamping force.

4. The ball clamping device (T) according to claim 1, characterized in that the ball socket (P) is constituted by a plurality of ball socket members (Pa, Pb...) which are partially or completely separated from one another and arranged circumferentially around the ball clamp.

5. a housing (G) for placement on the machine bed; a) in said housing (G) there is provided a fluid-biasable and fluid-deformable clamping means in the form of at least one radial spring (F) attached to said housing axis (Z ０ ) and b) said radial springs (F) are operatively connected with said ball sockets (P, Pa, Pb...) at their radially inner areas and supported at their radially outer ends on the housing wall; c) the radial springs (F) generate a clamping force directed radially inwards on the ball sockets (P, Pa, Pb...) in the clamped state, thereby causing the ball clamps (K, K) which are then biased by the ball sockets (P, Pa, Pb...) １ , K ２ . . .) clamps the shaft (W) surrounded by the ball clamp, a rotational movement about the shaft axis (Z), and A pivoting movement around the central point (M), and Sliding in the direction of the shaft axis (Z) relative to the housing (G); 2. The ball clamping device (T) according to claim 1, wherein the ball clamping device (T) is fixed so as not to cause a malfunction.

6. 2. The ball clamping tool (T) according to claim 1, characterized in that the mounting means (S) of the shaft (W) comprises a ball joint or metal bellows having a fixing pin (R) rotatable relative to the shaft (W), the fixing pin (R) being configured for a detachable connection with the workpiece to be fixed.

7. A method for machining a workpiece (U), in which the workpiece (D) can be fixed by at least one ball clamping device (T) according to any one of claims 1 to 6 relative to a machine bed (E) carrying said ball clamping device (T) through its mounting means (S) arranged on a shaft (W), said method comprising the following steps a): a) transferring at least one of said ball clamping devices (T) from a clamped state to a released state, thereby automatically allowing the workpiece or a workpiece area to move, starting from the clamping position it occupies in the clamped state, into a compensation position relative to the corresponding ball clamping device (T), thereby reducing or eliminating the stresses occurring between the workpiece and said ball clamping device (T) in the clamping position; A method comprising:

8. After step a), the following step b): b) transferring the at least one ball clamp (T) released in step a) back into a clamped state in order to again fix the workpiece relative to the machine bed in the compensation position it now occupies; The method of claim 7, wherein:

9. Next step c), c) the workpiece is machined while at least one of said ball clamps (T) is in a clamped state; 8. The method of claim 7, wherein the processing can include cutting, welding, gluing, soldering, bending, stamping, punching, hammering, and roll forming.

10. 9. The method according to claim 8, wherein at least one section of the workpiece is kept fixed to the machine bed through a fixed clamping means (L), while at least one of said ball clamps (T) is released and re-clamped according to said steps a) and b).

11. Before the workpiece is removed from the machine bed, steps a), b) and the following step c), c) the workpiece is machined while at least one of said ball clamps (T) is in a clamped state; The method of claim 8 , wherein the steps are performed multiple times in succession.

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