WO2024008237A1

WO2024008237A1 - Clamping system

Info

Publication number: WO2024008237A1
Application number: PCT/DE2023/100501
Authority: WO
Inventors: Tobias Ring
Original assignee: Tobias Ring
Priority date: 2022-07-05
Filing date: 2023-07-03
Publication date: 2024-01-11
Also published as: DE202022103760U1

Abstract

The invention relates to a clamping system (1) comprising a device for stamping defined recesses into a workpiece to be processed, a centring clamping means (2) with two clamping jaws (3), and the workpiece clamped therein for processing, wherein each of the clamping jaws (3), which can be moved via a clamp spindle (4), is provided with engaging elements (9), arranged in a row, in the form of protrusions or teeth, which protrude from corresponding contact surfaces of the clamping jaws (3), and the workpiece (7) has complementary recesses (10), wherein the engaging elements (9) on the clamping jaws (2) and the recesses (10) on the workpiece (7) are designed and positioned in alignment with one another, in such a way that the engaging elements (9) are designed to engage in the recesses (10) like a wedge, generating a force (A) in the workpiece (7) directed towards a contact surface (8) of the clamping jaws (3). In order to develop a clamping system, with more than one engaging element, in terms of its reliability in material-removing machining of a workpiece under high mechanical stress, according to the invention, a further row (15) of engaging elements (9) is arranged on each clamping jaw (3) spaced apart from and in parallel with a first row (14) of engaging elements (9).

Description

Clamping system

The present invention relates to a clamping system which includes a device for embossing defined recesses in a workpiece to be machined, a centering clamp with two clamping jaws and the workpiece clamped therein for machining.

Clamping systems with a centering clamp of the type mentioned are known in a large number of different designs from the prior art. Add to this e.g. B. DE 10 2014 112 845 Al and DE 20 2014 104 201 Ul provide an overview and disclose a clamping jaw quick-release system for precise processing with particular flexibility for use on different machines with different types of processing.

EP 2105257 A2 discloses the use of an additional screw connection in the vicinity of clamping surfaces on clamping jaws in addition to a clamping spindle for moving the clamping jaws of the centering clamp.

DE 10 2007 008 132 A1 and DE 10 2020 101 059 A1 teach the use of a separately applied marking to identify a preferred position on a workpiece, the workpiece fixed in a centering clamp being fixed in a mounting plate of a respective processing machine via separate foot bolts.

From DE 20 2020 100 356 Ul a clamping system is known in which, for clamping a workpiece in a machine vice or Centering clamp a base body, at least two mounted on the base body in a longitudinally displaceable manner and movable with one another via a clamping spindle for adjustment coupled clamping jaws are provided. The clamping jaws have form-fitting or Intervention elements in the form of projections or Teeth occupied, which protrude from corresponding contact surfaces of the clamping jaws. In a preparatory step, complementary recesses are stamped into the workpiece to be clamped for machining using an embossing device, which subsequently serve as coupling elements by engaging elements of the clamping jaws of the centering clamp in these recesses. The clamping system thus causes a mixed frictional and positive fixation of the workpiece, which enables the transmission of large holding forces with a small space requirement on the workpiece and on the clamping elements. In addition, DE 20 2020 100 356 U1 teaches that the engagement element should be designed to engage the recess in the manner of a wedge by generating a force directed in the workpiece onto a support surface of the clamping system. This force always presses the workpiece onto a defined contact surface under the influence of the clamping system. In addition to a defined and reproducible positioning of the workpiece in the clamping system, this prevents undefined lifting of the workpiece. The tendency of the workpiece to vibrate during machining is also reduced.

Devices according to the teaching of DE 20 2020 100 356 Ul have also proven themselves in the area of machining workpieces in a clamping system on five of the basically six existing outer sides without re-clamping the workpiece.

The present invention has the task of further developing a clamping system with more than one engaging element in terms of its reliability during machining of a workpiece under high mechanical stress. This object is achieved according to the invention by the features of claim 1 in that on each clamping jaw a series of engagement elements, which are designed in accordance with the teaching of DE 20 2020 100 356 Ul, a further row of engagement elements at a distance in parallel is arranged.

In an upstream work step, a workpiece is provided with corresponding depressions by plastic deformation in an embossing device with embossing teeth in areas that are intended for clamping in a centering clamp during machining, which are now also arranged in two rows according to the present invention. The embossing teeth of the embossing device and the engagement elements of the centering clamp are positioned as parts of the clamping system in such a way that they are coordinated with one another relative to the workpiece, so that in the case of positive and force-fitting engagement of the engagement elements, for example. B. A height offset of the recesses in the workpiece compared to the engaging elements causes a pull-down effect, through which the workpiece is placed in a defined manner on a base or Support surface is pressed. The advantage of the new clamping system compared to that according to DE 20 2020 100 356 U1 is that a maximum moment, as is caused in the course of machining on a workpiece in question, is now significantly increased. The reason is that the lever conditions on the workpiece are improved by the second row of engaging elements arranged at a distance and parallel to a first row of engaging elements and their distance from the first row of engaging elements, as will be discussed below an exemplary embodiment is described in detail.

Advantageous further training is the subject of the dependent claims. In a preferred embodiment of the invention, the two rows of engagement elements are each Clamping jaws against each other approx. 6 mm to about 7 mm offset. When arranging the bottom row of engaging elements of the respective clamping jaws, preferably approx. 3 mm above a lower edge of the clamped workpiece results in an area of approx. 10 mm height that is required on a workpiece for recesses in order to form a compact clamping system with significantly improved properties using a centering clamp described above.

Advantageously, in one embodiment, the engaging elements of the rows are arranged aligned with one another.

A centering clamp described above can in principle also be provided for preparing a workpiece in the function of an embossing device. However, it is advantageous to provide a separate embossing device, the structure of which essentially corresponds to the centering clamp mentioned, but here clamping jaws with two mutually parallel rows of engaging elements are provided, which are opposite the rows of clamping jaws of the centering clamp Height offset by approx. + 1/10 mm compared to a contact surface of the workpiece. This results in recesses on each workpiece after it has been inserted into the centering clamp, in which not only an exact and reproducible alignment but also a pull-down force is created.

Preferably, hydraulics are also provided in the embossing device instead of the clamping spindle of the centering clamp. In this step of embossing, as part of prefabrication, high forces are conveniently and quickly applied to emboss predetermined depressions in the workpiece.

It is further preferred that the clamping jaws are designed to be replaceable as highly stressed wearing parts. The applies to the centering clamp as well as to the embossing device.

Further features and advantages of embodiments according to the invention are explained in more detail below with reference to exemplary embodiments using the drawing. It shows in a schematic representation:

Figure 1: a three-dimensional view of an exemplary embodiment of a centering clamp;

Figure 2: a side view of the centering clamp from Figure 1;

Figures 3a and 3b: a detail of Figure 2 and an enlarged representation of a sectional view of the engagement elements of the clamping jaws of the centering clamp that engage in recesses in the workpiece;

Figure 4: a side view of an application of the clamping system;

Figure 5: a partially sectioned representation of an engagement of an engagement element in a recess of the workpiece with an indication of relevant forces and

Figure 6: a three-dimensional view of a known centering clamp.

Across the various illustrations, the same reference symbols are always used for the same elements. Without limiting the invention, the following is just a clamping system shown and described using a cuboid workpiece in a centering clamp. However, it is obvious to the person skilled in the art that appropriately shaped engagement elements can also be used on a chuck of a lathe or a turning and milling center with the same mechanical effect to achieve the advantages mentioned at the beginning on a correspondingly shaped and prepared workpiece.

Figure 6 represents a three-dimensional view of a known clamping system 1 with a centering clamp 2 according to the teaching of DE 20 2020 100 356 Ul. Between two clamping jaws 3, which are coupled to one another for adjustment via a clamping spindle 4 and are displaceably mounted on a web 5 of a base body 6, a workpiece 7 - not shown here for reasons of clarity - is fixed, generating forces A directed towards support surfaces 8 , as will be explained in detail below using the illustration in FIG. 5. The centering clamp 2 and the workpiece 7 prepared accordingly by embossing recesses 10 together form the clamping system 1, which has fundamentally proven itself in 5-axis machining with material removal, especially under high mechanical loads.

Figure 5 shows an enlargement of Figure 6 in a sectional view to illustrate the generation of a force A directed towards a support surface 8 in the course of fixing the workpiece 7 in the centering clamp 2. Accordingly, an engagement element 9 is provided at a free end of a clamping jaw 3 of the centering clamp 2, which is opposite the support surface 8 of the centering clamp 2, and protrudes there. In the state shown with a workpiece 7 fixed in the centering clamp 2, the engagement element 9 on the clamping jaw 3 engages in a recess 10 in the workpiece 7 a. A flank 11 is formed on the engagement element 9 and/or the recess 10, which has an angle a relative to a force F that lies between 0° and 90°, but preferably between 30° and 60°. Here this angle a is approximately 45°. So that the force F can act undisturbed on the workpiece 7, the engagement element 9 is designed in coordination with the recess 10 so that in the situation shown it has multi-surface recesses 12 in contact with the recess 10 of the workpiece 7. In these recesses 12, the engagement element 9 is not in contact with the workpiece 7, so that no force transmission takes place here. In an ideal case, the engagement element 9 is in contact with the workpiece 7 only via the flank 11 in the recess 10. Under the model assumption of a single force application point for the force F, a vectorial decomposition of the above results on the flank 11, which can be represented in the form of a force parallelogram the engagement element 9 acts on the workpiece 7 by partial forces: a force A directed towards the support surface 8, which causes the desired pull-down effect of this clamping system 1, and a force B running in the horizontal direction, which is caused by an equal force from the opposite force on the workpiece acting clamping jaws 3 is compensated with a corresponding engagement element 9.

1 and 2 now show a three-dimensional view of an exemplary embodiment of a novel centering clamp 2 with a side view, from which a two-line arrangement of engagement elements 9, which are designed according to the teaching of DE 20 2020 100 356 Ul, in a lower row of teeth 14 and an upper row of teeth 15 can be seen on the mirror-symmetrically constructed clamping jaws 3 of the centering clamp 2. The engagement elements 9 of the two rows 14, 15 are arranged in alignment with one another. Figure 3a shows a detail A of Figure 2, indicating a dimension according to a preferred exemplary embodiment of the present invention. Accordingly, the rows 14, 15 of engagement elements 9 on the clamping jaws 3 run parallel to one another at a distance of approx. 6 mm arranged. Based on the contact surface 8, there is a lever a of 3 mm for a lower row of teeth 14 to absorb a moment, for the second or Upper row 15, however, has a new lever b of approx. 10mm. As a result, a significantly larger moment can be absorbed by the second, upper row of teeth 15.

The illustration of Figure 3b shows an enlarged view of a sectional view of engagement elements 9 of the clamping jaws 3 of the centering clamp 2 engaging in recesses 10 of the workpiece 7. By pressing the clamping jaws 3 onto the workpiece 7, forces are generated on both rows of teeth 14, 15, through which the workpiece 7 is pressed together onto the support surface 8 of the clamping jaw 3, as already described in FIG. 5, but now with doubling the force attack fs points of the clamping jaws 3 on the workpiece 7.

Figure 4 shows a side view of a corresponding application of the clamping system 1, of which Figure 3b shows an enlarged detail. Based on a workpiece 7 to be machined with a height h of 150 mm, this results in a leverage ratio of 1:50 for a lower row 14 of engaging elements 9. In relation to the upper row 15 of engaging elements 9, however, there is a significantly more favorable leverage ratio of only approx. 1:17. This means that during mechanical machining, significantly higher moments can be applied to the workpiece 7 to be machined, without a secure, precise and reproducible fixation of the workpiece 7 between the clamping elements. Jaws 3 of the centering clamp 2 could be lost. Since both rows 14, 15 of engaging elements 9 cause a pull-down effect on the workpiece 7, the workpiece 7 is also pressed strongly onto the support surface 8.

In the zone bordered by dots, FIG. 4 shows a case in which a workpiece 7 has not been prepared precisely enough, e.g. B. due to an imprecise embossing of the recesses 10 in the workpiece 7 or here a deviation Z from a predetermined external geometry of the workpiece 7. Here the workpiece 7 does not rest on the support surface 8 even after it has been clamped, as is the case, for example. B. This could also be the case with a warped workpiece. Nevertheless, the engaging elements 9 of the two rows 14, 15 exert sufficiently high holding forces via the recesses 10 to ensure safe and precise work even at high cutting and/or feed speeds when machining the workpiece 7 with a correspondingly large moment load to be able to guarantee. The rows 14, 15 of intervention elements 9 also ensure exact and reproducible positioning of the device with the accuracy or Workpiece 7 with quality defects in the centering clamp 2.

To prepare a workpiece 7, a separate embossing device (not shown in the drawing) is basically provided as part of the clamping system 1. In one exemplary embodiment, the structure of the embossing device essentially corresponds to that of the centering clamp 2. So here too, clamping jaws 3 are installed with two parallel to each other at a predetermined distance of approx. 6 mm rows 14, 15 of engagement elements 9 are used. In contrast to the clamping jaws 3 of the centering clamp 2, the embossing device has a height offset of approx. + 1 / 10 mm compared to one

Support surface 8 of the workpiece 7 is set. This Height offset serves to generate the pull-down effect described above on both rows of teeth 14, 15 when clamping the workpiece 7 in the centering clamp 2. The geometries of the rows of teeth 14, 15 of the clamping jaws 3 of the centering clamp 2 and of the embossing device are essentially identical.

In an exemplary embodiment not shown, the clamping spindle 4 in the figures in FIGS. 1, 2, 4 is also replaced by a hydraulic system. In this prefabrication step, high forces can be applied conveniently and quickly to emboss the recess 10 in the workpiece 7.

Also not shown in the drawing, the clamping jaws 3 of at least the centering clamp 2 are designed to be replaceable in one exemplary embodiment. The same is also possible with a height offset of approx. + 1 / 10 mm according to modified clamping or Embossing jaws of the embossing device are provided. In the case of the embossing jaws of the embossing device, this height offset is realized in an exemplary embodiment not shown further by a targeted lowering of the support surfaces 8 of the embossing jaws 3. Since the respective engagement elements 9 are subjected to high mechanical stress, they are subject to increased wear and must therefore be easy and quick to replace.

Finally, the illustrations in Figures 1, 2 and 4 in particular show a very compact and low-profile centering clamp 2. This centering clamp 2 enables precise and process-reliable repeatable positioning with a small space requirement on a workpiece itself, allowing machining of workpieces of maximum size while maintaining the required minimum tool travel distances. Due to the advantages mentioned, such clamping systems 1 have a wide range of uses in machining production. Reference symbol list is te

1 clamping system

2 centering clamps

3 clamping jaws

4 clamping spindles

5 jetty

6 Base body of the centering clamp 1

7 workpiece

8 Support surface on the clamping jaw 3 or another appropriately designed part of the centering clamp 2

9 intervention element

10 recess in the workpiece 7

11 flank

12 Exemption / exemption

13 edge

14 lower row of teeth

15 upper row of teeth a lever of a lower row of teeth 14

A Force, pull-down force directed towards the support surface 8 b Lever of a 2. , upper row of teeth 15

B force in horizontal direction

F Clamping force between the clamping blocks 2 h Height of the workpiece 7

Z geometric deviation of the workpiece 7 from a specification a angle between the flank 11 and the attacking clamping force F

Claims

Claims clamping system (1), which comprises a centering clamp (2) with two clamping jaws (3), a workpiece to be machined (7) and a device for embossing defined recesses (10) in the workpiece (7), each of which has a clamping spindle (4) movable clamping jaws (3) are occupied by engaging elements (9) arranged in a row in the form of projections or teeth which protrude from corresponding contact surfaces of the clamping jaws (3), and the workpiece (7) has complementary recesses (10) has, wherein the engagement elements (9) on the clamping jaw (2) and the recesses (10) on the workpiece (7) are designed and positioned in such a way that they are coordinated with one another in such a way that the engagement elements (9) are in the manner of a wedge, producing an in The force (A) directed towards the workpiece (7) on a support surface (8) of the clamping jaws (3) is designed to engage in the recesses (10), characterized in that on each clamping jaw (3) at a distance and parallel to a first Row (14) of engagement elements (9) a further row (15) of engagement elements (9) is arranged. Clamping system (1) according to the preceding claim, characterized in that the two rows (14, 15) of engagement elements (9) of the respective clamping jaws (3) are arranged offset from one another by approximately 6 mm. Clamping system (1) according to one of the preceding claims, characterized in that the engagement elements (9) of the rows (14, 15) are arranged aligned with one another. Clamping system (1) according to one of the preceding claims, characterized in that the lower row (14) of engagement elements of the respective clamping jaws (3) is approximately 3 mm above a lower edge of the clamped workpiece

(7) is arranged. Clamping system (1) according to claims 3 and 4, characterized in that for preparing a workpiece (7), an embossing device is provided, the structure of which essentially corresponds to the centering clamp (2), with clamping jaws (3) having two parallel to each other Rows (14, 15) of engagement elements (9) are provided, which have a height offset of approximately +1/10 mm compared to a support surface of the workpiece (7) compared to the rows (14, 15) of the clamping jaws of the centering clamp. Clamping system (1) according to claim 5, characterized in that hydraulics are provided in the embossing device between the clamping jaws (3). Clamping system (1) according to one of the preceding claims, characterized in that the clamping jaws (3) are designed to be replaceable as heavily stressed wearing parts in the embossing device and the centering clamp (2).