Patent Application
20190084054
This application claims the priority of EP 17191263.7 filed on 2017 Sep. 15; this application is incorporated by reference herein in its entirety.
The invention relates to a coupling device according to the preamble of claim 1.
Such a coupling device is known from EP 1 837 107 B1. This coupling device is used for coupling a hollow shaft taper to a receiver provided on the machine tool and comprises a collet having individual clamping segments and, at one end, at its outer circumference, an annular collar having a wedge-shaped annular surface. Additionally provided is a tension rod with a head having a radial ridge. This head pushes towards the clamping segments for clamping, with the clamping segments being deflected radially outward into the hollow shaft of the hollow shaft taper.
At its other end opposite the annular collar, the collet has an engagement collar having a radial surface that presses on a fixed axial support of a part of the receiver. The collet is made in one piece and provided at its rear part with an end-side ring that pivotably supports the collet on the tension rod on the inside and on an external support on the outside, with a thin-walled jacket section of the clamping segments, which forms a joint, being located adjacent to the ring. Radial deflection of the clamping segments is performed using the joints on the rear part of the collet.
In the rear part of the collet, the clamping segments have chambers for providing the clamping segments with the features of a spring cup.
The chambers thus form spring elements that generate the reset forces during the deflection of the clamping segments.
An advantage of this coupling device is that the collet is made in one piece; i.e., the number of parts can thus be kept low, significantly reducing the manufacturing effort and expense.
It is further advantageous that the one-piece collet can be manufactured to be exactly rotation-symmetrical, which allows achieving a high level of balance quality even at high rotational speeds.
A disadvantage of this coupling device is that it is very prone to wear. The chambers at the rear end of the collet, which have cup spring features and thus form spring elements, are especially wear-prone. These chambers are exposed to high mechanical loads, especially torsion loads. This usually results in premature breaking of these spring elements, undesirably reducing the lifespan of the collet.
The invention relates to a coupling device for coupling a hollow shaft taper to a receiver provided on the machine tool, having a collet and a tension rod by means of which the collet can be brought into a release position or a clamping position. The collet is embodied in one piece and has several clamping segments extending in its longitudinal direction. Upon moving the collet into the clamping position, said clamping segments are moved in a radial direction against spring forces exerted by the spring element. The spring elements are an integral part of the collet. Each spring element between two adjacent clamping segments is provided to extend in the longitudinal direction of the latter.
The task of the invention is to provide a coupling device of the kind mentioned initially, which has a robust, wear-resistant construction while requiring low manufacturing effort and expense.
For solving this problem, the features of claim 1 are provided. Advantageous embodiments and useful further developments of the inventions are described in the dependent claims.
The coupling device according to the invention is used for coupling a hollow shaft taper to a receiver on the machine tool, with said device having a collet and a tension rod by means of which the collet can be brought into a release position or a clamping position. The collet is embodied in one piece and has several clamping elements extending in the collet's longitudinal direction. When the collet is moved into the clamping position, said clamping elements are moved in the radial direction against spring forces exerted by the spring element. The spring elements are an integral part of the collet. Each spring element between two adjacent clamping segments is provided to extend in the latters' longitudinal direction.
The coupling device according to the invention functions in that the collet is movable between a clamping position and a release position by actuating; i.e. shifting the tension rod. In the clamping position, the collet holds the hollow shaft taper in place in a target position on the receiver such that machining processes are performed using a tool supported in the hollow shaft taper. In contrast, in the release position of the collet, the hollow shaft taper is released and can be swapped, if applicable.
The basic idea of the invention consists in arranging the spring elements so that they extend in the longitudinal direction of the clamping segments as integral parts of the collet. Consequently, the spring elements embodied thus can have a great longitudinal extension, with these spring elements extending almost over the entire length or, especially advantageously, over the entire length of the clamping segments. As a result, the spring elements perform only very small deflection motions when the clamping segments are radially deflected, especially when the collet is moved into its clamping position. This, in turn, has the effect that the spring elements are exposed to merely low mechanical loads during the operation of the coupling device so that there is no wear worth mentioning of the spring elements even during long operating periods. Consequently, the collet has a long lifespan, thus realizing overall robust construction of the coupling device.
Another significant advantage results from the one-piece construction of the collet, which allows holding the number of individual parts of the coupling device low, minimizing the manufacturing effort and expense by allowing to produce the spring elements together with the clamping segments in one manufacturing step.
Further advantageous are the identically embodied clamping segments. And the spring elements are also embodied identically. Here, the clamping segments and the spring elements form a rotation-symmetrical arrangement relative to the longitudinal axis of the collet.
Due to the resulting complete rotation symmetry of the collet the latter has, contrary to a collet based on individual clamping segments, a high level of balance quality even at high rotational speeds. Thus, the coupling device is usable in HSC (high speed cutting); i.e., high speed machining. In addition, the collet can also be designed for high clamping forces.
Further advantageous is the simple contour of the collet, which has positive effects for the manufacturing process. Here, the shape of the collet is selected such that the collet meets the requirements of DIN 69063-S.
According to an advantageous embodiment of the invention, each clamping segment forms a joint at its rear end. These joints are supported in a recess in the receiver on the machine tool.
In addition, each clamping segment has at its front end a collar segment. The collar segment has a slanted surface against which rests a head of the tension rod. The collar segment further has a contact surface against which rests a segment of the hollow shaft taper.
Here, a spring element extends from the joint to the collar segment of a clamping segment.
Upon actuation of the tension rod, the clamping segments thus perform pivoting motions relative to the pivot axes running through the joints.
When the collet is moved into the clamping position, the contact areas of the collar segments of the clamping segments are brought in engagement with the hollow shaft taper so that the latter is held in place in the receiver.
When the collet is moved into the release position, the contact areas of the collar segments of the clamping segments are brought out of engagement with the hollow shaft taper, the reset forces of the spring elements moving the clamping segments into their original positions.
As the spring elements extend from the joints on the rear end of the collet to the collar segments at the front end, thus extending almost over the entire length of the clamping segments, the spring elements need to perform merely small deflection motions. In addition, this results in uniform force distribution via the spring elements. Thus, low spring element wear and accordingly long collet lifespans are achieved.
Especially advantageously, the spring elements embody leaf spring elements so that they are not exposed to torsion loads.
According to an embodiment of the invention that is particularly advantageous with regard to design, each spring element has two arms extending at a distance from each other. These arms are connected to each other at a longitudinal end of the spring element by means of a connecting web.
The resulting spring element is embodied in the shape of a mirror-symmetrical fork. The arms of the spring elements extend essentially in parallel at a distance from each other, with both arms being arranged in each space between two adjacent clamping segments. Here, each arm is molded to its associated clamping segment at the originally free arm end.
Each arm is connected to the associated clamping segment only by means of this molding at its free end. The rest of the arm extends at a distance from the clamping segment and is thus movably supported so that the arms are elastically deformable over almost their entire length. Thus, the forces are distributed over the entire length of the spring element when a force is applied. Due to the great length of the spring elements, merely small deflections of the arms will result upon impingement of a force; consequently, the spring element is not prone to wear.
The invention is explained below based on the drawings. The following is shown in:
The receiver 3 contains a through-bore in the axial direction, in which a tension rod 4 is shiftably supported in its longitudinal direction. The tension rod 4 has a head 4a at its front end.
The tension rod 4 is embodied in the shape of a hollow body, with a guide 5 of the hollow shaft taper 2 protruding into the hollow body. The tension rod 4 can thus slide on the guide 5, rendering said rod positively guided.
The coupling device 1 further has a collet 6, with a part of the collet 6 being supported in a sleeve 7 arranged in the receiver 3. By sliding the tension rod 4, the collet 6 is movable between a clamping position and a release position.
The longitudinal axes of the clamping segments 8 run in parallel with each other and in parallel with the longitudinal axis of the collet 6.
Each clamping segment 8 has a central segment 8a having an essentially constant cross-section. The outer surfaces of these spacers of the clamping segments 8 lie on a cylindrical jacket surface of the collet 6.
At the rear end of each clamping segment 8, a joint 10 is embodied. This joint 10 is embodied in the shape of a broadened cross-section of the clamping segment 8. The joint 10 has a rounded contour. Each joint 10 is supported in a recess 11 in the receiver 3. Thus, each clamping segment 8 is pivotably supported in the receiver 3, with the pivot axis running through the joint 10.
At a small distance from the joint 10, an annular segment 12 abuts that protrudes from the outside of the central segment 8a of a clamping segment 8. The annular segments 12 of all the clamping segments 8 complement each other to form an annular structure which, as shown by
At the front end of each clamping segment 8, a collar segment 13 is provided that protrudes over the outside of the central segment. Here, at the border between the collar segment 13 and the central segment, a contact surface 14 in the shape of a step is embodied.
The inside of the collar segment 13 is embodied in the shape of a slanted surface 15. This slanted surface 15 matches the contour of the head 4a of the tension rod 4.
As shown in
Generally, the spring element 9 can also extend merely over part of a clamping segment 8.
In this case, each spring element 9 is embodied as a leaf spring element. The spring element 9 embodied thus has two arms 16 extending essentially in parallel at a distance from each other and being connected at one of their longitudinal ends by means of a connecting web 17. The arms 16 are embodied to be mirror-symmetrical relative to a mirror plane. Each arm 16 is molded at its free end to its associated clamping element 16, with a bulge 18 which protrudes for this purpose on the free end of the arm 16 forming the connection to the clamping segment 8. Thus, each arm 16 extends, starting from this connecting spot, at a small distance from its associated clamping segment 8.
The mode of functioning of the collet 6 embodied thus in the coupling device 1 is such that when the collet 6 is moved into its clamping position by means of the tension rod 4 by inserting the head 4a of the tension rod 4 into the cavity of the collet 6, a force impinging radially from this head 4a is exerted on the slanted surfaces 15 of the clamping segments 8 such that these are pushed radially outward. Due to this, the clamping segments 8 perform pivoting motions relative to the pivot axis running through the joints 10. Here, the spring elements 9 are spread out, thus exerting reset forces countering this motion.
When, as the
When the tension rod 4 is then moved back in order to release the hollow shaft taper 2, the clamping segments 8 return into their original position due to the return forces of the spring elements 9. The collet 6 is then in the release position shown in the
| Number | Date | Country | Kind |
|---|---|---|---|
| 17191263.7 | Sep 2017 | EP | regional |
