Patent Application
20060104711
This invention relates to a method for creating a releasable connection between two components, wherein the first component is elastically deformed such that a clamping surface of the deformed component corresponds to a corresponding clamping surface of the other component with predetermined play, and the two components can be inserted into one another, and wherein a pressure connection is created after the two components have been inserted into one another when the deformed component is elastically reformed. Furthermore, the invention relates to a component system for carrying out the method.
Methods for creating a friction locking connection between two components of this type are known, for example from DE 195 21 755 C1 and DE 196 24 048 A1. With these methods, in a corresponding way, a polygonal or oval component is inserted elastically into a round shape by applying radial pressure forces so that a round shaft can be fitted while maintaining the radial pressure forces. If the radial forces are then reduced or lifted, the deformed component springs back into its oval or polygonal initial shape so that the shaft is fixed therein by means of a pressure fit.
This type of connection between two components has proven to be of value in practice. However, it is partially considered disadvantageous that the complexity of the apparatus required to apply the radial pressure forces is relatively high and it requires a lot of space.
Against this background, this invention is based upon the aim of creating a method and a component system of the type specified at the start which make it possible to apply the forces required for deformation with low apparative complexity and with a small overall size.
This aim is fulfilled according to the invention in that the first component is elastically deformed when axial forces, and in particular tractive forces, are exerted upon force transmission sections of the component, whereupon the axial forces are converted into the desired radial deformation or movement of the clamping surface by means of joints which are provided between the force transmission sections and the clamping surface. The invention is thus based upon the idea of deforming the first component in the desired manner by applying axial forces, instead of applying radial pressure forces as in the prior art. These axial forces are then converted into the desired deformations of the clamping region by the joints which are provided between the force transmission sections and the clamping surface and for example can be in the form of solid body joints or also of pivot joints or hinges. It has been shown that this design makes it possible to produce comparably large clamping paths. By means of the large clamping paths a comparably large amount of joint play occurs between the components to be connected which can be around 0.3% of the clamping diameter, and makes possible automatic joining of the components to be connected. It is also advantageous that the deformations substantially occur in the region of the (solid body) joints whereas the clamping surface itself remains level as far as possible, by means of which optimal alignment is achieved. This is particularly applicable if the first component is formed like a sleeve in its clamping region and is provided with axial slits which guarantee that the clamping sleeve is easily deformed around its circumference.
Basically, it is possible to convert both axial pressure forces and axial tractive forces into radial deformations. According to the invention however, it is preferable to use tractive forces in order to achieve the desired deformations.
In order to convert axial tractive forces particularly effectively into radial deformations of the clamping region, the clamping surfaces of the clamping region on the one hand and the points of application of the tractive forces should be spaced apart from one another radially. If for example the first component is in the form of a mandrel with a clamping surface on the outside, the force transmission sections should lie radially within the clamping surface, and if the first component is in the form of a chuck with a retainer for a component to be clamped, the force transmission regions lie radially outside of this retainer.
If the first component is in the form of a mandrel with a clamping surface on the outside, according to one embodiment of the component system according to the invention, it is proposed that the clamping means for applying the axial tractive forces are provided in a through boring of the first component.
A constructive design of this embodiment can for example consist of one end of the first component being closed, and the clamping means being provided in order to exert a pressure force on the closed end, and so to transmit axial tractive forces into the first component.
According to a concrete embodiment, a nut is adjustably screwed into the through boring at its axial end lying opposite the closed end, pressure transfer means being provided between the closed end and the nut, so as to exert a pressure force onto the closed end when the nut is screwed in the direction of the closed end, and so transmit a tractive force into the first component. With this embodiment, just one rotation of the nut is sufficient in order to deform the clamping region of the mandrel so as to attach or detach a component.
Alternatively, it is possible to provide a hydraulically or pneumatically operated piston on the end of the first component lying opposite the closed end, pressure transfer means also being provided here between the closed end and the piston, in order to exert pressure force on the closed end by operating the piston, and thus transmit a tractive force into the first component. The piston here can be movably disposed directly in the open end of the first component.
The pressure transfer means can be formed simply by a pressure transfer rod. In order to reduce tensions or friction forces, the pressure transfer means advantageously have balls at least in the contact regions with the nut or the piston on one side and the closed end of the first component on the other side.
According to another embodiment, the component system according to this invention is designed such that a spindle is disposed in the through boring of the first component, which spindle, at its one end region, is mounted rotatably and so that it is axially movable in the first component, and at its other end region passes through a spindle nut which is mounted rotatably but so as to be axially secure in the first component, and can be driven rotatably, stops which come into contact with one another being provided on the spindle and the first component when the spindle is moved in an axial direction. With this embodiment, a rotation of the spindle nut is converted into an axial movement of the spindle which comes into contact with the stop of the first component and so exerts a pressure force thereupon. With this embodiment the through boring of the first component can also be closed so as to form a stop with which the drive spindle comes into contact.
Finally and alternatively, a rotatably driveable thread shaft can be disposed, axially securely, in the through boring of the first component, the first component being fixed on a first side of the clamping region, and a spindle nut being held in the first component on the opposite side of the clamping region, said spindle nut being engaged with a threaded section of the spindle shaft so that a rotation of the spindle shaft is converted into an axial movement of the spindle nut and of the component section connected in this, by means of which tractive forces are transmitted into the first component if this is held on the opposite first side of the clamping surface.
If the first component is in the form of a chuck with a retainer for the component to be clamped, according to a preferred embodiment of the invention it is proposed that the chuck has power transmission flanges on both axial sides of the clamping region and that a clamping device is disposed between the force transmission flanges in order to transmit tractive forces into the first component by means of the force transmission flanges. The clamping device here can be in the form of a piezo element or electrically driven positioning element which lies against the power transmission flanges and expands when current is introduced. Alternatively, the clamping device can have two eccentric rings which are rotatable in relation to one another, which lie against the force transmission flanges and are designed in such a way that their axial expansion changes if they are rotated in relation to one another. Finally, it is also possible to design the clamping device as a threaded ring which is screwed onto the one force transmission flange and comes into contact with the other force transmission flange with a front side. These last two embodiments offer the advantage that deformation of the clamping region can be brought about by manual rotation of the eccentric rings or the threaded ring.
According to an alternative application of the concept according to the invention, it is also conversely possible to convert radial forces into axial length changes. For example, by means of corresponding joints and solid body joints it is possible for radial pressure forces to be converted into axial expansions of a component. An example of an application for this according to the invention is a clamping force tester for checking the clamping force or the clamping path with hydraulic expansion chucks with a substantially cylindrical housing, a testing bolt held so as to be axially movable within the housing, said bolt being acted upon by an elastic means in the direction of the one housing end, and a display which shows a relative movement between the housing and the testing bolt. With this example of an application, the cylindrical housing is inserted into the central tool retainer of a tool holder to be tested, and then a pressure is produced by the clamping system of the tool holder in the region of the clamping surface, said pressure being converted by means of the solid body joints provided into a length change of the housing AL. This change in length is dependent upon pressure and approximately linear to the position and size of the pressure applied. The actually effective clamping force, the clamping path and the torque to be expected can be deduced from this measurement value.
With regard to additional advantageous embodiments of the invention, one should refer to the sub-claims and to the following description of examples of embodiments with reference to the attached drawings.
In the drawings:
FIGS. 1 to 3 show a first component system according to this invention with a first component 1 in the form of a mandrel and an annular second component 2 which can be detachably connected to the mandrel 1 in the way shown in
As can be seen clearly in
With this component system 1, 2, the annular component 2 is attached to the clamping sleeve 4 of the mandrel 1 by means of a pressure fit 4. This is created when the clamping sleeve 4, the outer diameter of which in untensioned state is a little greater than the inner diameter of the annular component 2 to be clamped, is elastically deformed inwards so that the annular component 2 can be pushed onto the clamping sleeve 4, and subsequently a pressure connection is created between the two components when the clamping sleeve 4 is elastically reformed.
According to this invention it is proposed that this deformation of the clamping sleeve 4 is brought about by means of axial tractive forces which are introduced via the end sections 6, 7 into the base section 3 of the mandrel 1. In order to produce these tractive forces 7, a clamping device 10 is provided in an axial, central through boring 9 of the mandrel 1. Two nuts 11, 12 belong to this clamping device 10, which are screwed into the axial end regions of the through boring 9 and close the same, and pressure transfer means 13, 14, which are disposed between the nuts 11, 12 in the through boring 9 so as to allow a transfer of pressure forces between the nuts 10, 11. In the example of an embodiment shown, the pressure transfer means 13, 14 comprise a central pressure transfer rod 13 which passes through the clamping sleeve 4, a steel ball 14 being provided respectively between the axial ends of the pressure transfer rod 13 and the nuts 11, 12 so as to keep any friction forces occurring as small as possible.
If one of the nuts 11, 12 is screwed into the mandrel 1 in the direction of the other nut 12, 11, this leads to compressive stresses D occurring in the clamping device 10 and as a reaction, tensile stresses Z occurring in the base section 3 and the stop element 8 fastened securely to the same.
In order to convert these tensile stresses Z into the desired, inwardly directed deformation of the clamping sleeve 4, on the one hand it is proposed that the transmission of the tractive forces from the clamping device 10 into the mandrel 1 happens radially within the clamping sleeve 4. Moreover, the thick-walled end regions 6, 7 of the base section 3 are connected to the clamping sleeve 4 by means of thin-walled solid body joints 15, 16 of the clamping sleeve 4 which on their radial outer ends are subjected to a torque which corresponds to the radially inwards working tractive forces and by means of which the upper ends of the joints 15, 16 and so also the clamping sleeve 14 are moved inwards, as shown by the arrow M in
The result which is achieved here by the solid body joints 15, 16 is similar to that of pivot joints 15, 16, as shown schematically in
Basically it is also conversely possible to exert axial pressure forces on the end sections 6, 7 of the base section 3 so that the axial end sections 6, 7 are pressed together, and this leads to a pivotal movement of the joint lever 15, 16 in the opposite direction to arrow M, with the result that the clamping sleeve 4 is moved outwards.
In other words, with the mandrel 1 shown in FIGS. 1 to 3, the clamping sleeve 4 is moved inwards so as to attach or detach the second component 2, when one of the nuts 10, 11 rotates into the mandrel 1, and in this way tractive forces are produced in the mandrel 1. The rotation rate which can be achieved here by means of the solid body joints 15, 16, is relatively high so that high levels of joint play can be established. Furthermore it is advantageous that deformations substantially only occur in the region of the solid body joints 15, 16 whereas the clamping sleeve 4, and in particular the clamping surface 4a of the same remains as even as possible, by means of which optimal axial alignment is achieved. Finally, when the clamping sleeve 4 reforms, the clamped component 2 is pulled against the stop element 8 so that optimal axial alignment can be guaranteed.
In
A third embodiment of a mandrel 1 according to the invention is shown in
An alternative fourth embodiment is shown in
In FIGS. 8 to 10 embodiments are shown with which the first component 1 of the component system according to the invention is in the form of a chuck with a central retainer 26 for a component to be clamped (not shown in detail). The retainer 26 is provided here in a clamping sleeve 4 which, divided up circumferentially has six axial slits 5 so as to allow extensions and contractions for the clamping sleeve 4. The clamping sleeve 4 is connected to flange-like outwardly protruding end sections 6, 7 of the base section 3 by means of solid body joints 15. Between these flange-type end sections 6, 7, and radially outside of the clamping sleeve 4, a clamping device 27 is provided which offers the possibility of exerting pressure forces on the end sections 6, 7 in the direction of the arrow D so that tensile stresses Z occur in the base section 3 which are converted into downward movements of the clamping sleeve 4 by means of the solid body joints 15, 16, in the way already described, said clamping sleeve in this case being expanded so that a component 2 to be clamped can be inserted in the retainer 26.
With the example of an embodiment shown in
Alternatively,
With the embodiment shown in
If with this embodiment the threaded ring 27 is further screwed onto the left end section 7, it presses against the right end section 6, by means of which the desired tractive force Z is produced in the base section 3.
In
If, as is shown in
Thus, from the measured length-change which is indicated on the display (35), the actually effective clamping force can be deduced, and thus, also the clamping path and the torque to be expected.
| Number | Date | Country | Kind |
|---|---|---|---|
| 04 020 289.7 | Aug 2004 | EP | regional |
This application is based upon application no. 04020289.7, filed August 26, 2004 with the European Patent Office, the disclosure of which is incorporated herein by reference.
