PROBE DEVICE WITH SPIRAL SPRING, ROTATING HEAD AND TESTING APPARATUS

Abstract

A probe device for a rotating head has at least one support arm that is mounted so as to rotate around an axis of rotation, at least one probe that is joined to the support arm, and at least one spring element that can be supported on the rotating head and engages at the support arm and that is provided for exerting a force on the support arm, which, as a result of this force, experiences a torque with respect to the axis of rotation. The support arm has at least one mount, which is concentric with the axis of rotation, for the spring element, which, when arranged on the mount, is bent at least in part around the axis of rotation. As a consequence, centrifugal forces that act on the spring element when the rotating head is in operation have no influence on the tension of the spring element.

Claims

1. A probe device for a rotating head, comprising: at least one support arm that is mounted so as to rotate around an axis of rotation, at least one probe that is joined to the support arm, and at least one spring element supported on the rotating head and engaged at the support arm and that is provided for exerting a force on the support arm, which, as a result of this force, experiences a torque with respect to the axis of rotation, wherein the support arm has at least one mount, which is concentric with the axis of rotation, for the spring element, which, when arranged on the mount, is bent at least in part around the axis of rotation.

2. The probe device according to claim 1, wherein the spring element is a torsion spring or a spiral spring or an elliptical spring or a parabolic spring or a wave spring or a wire spring or a leg spring.

3. The probe device according to claim 1, in which the spring element has a support segment for supporting it at a stop of the rotating head.

4. The probe device according to claim 1, further comprising: at least one mechanical delimiter of the angle of rotation for the support arm and/or the probe.

5. The probe device according to claim 1, further comprising: at least one cable conduit for guiding a probe cable, wherein the cable conduit has a first end segment that extends along the support arm from the probe to the axis of rotation and a second end segment that substantially starts from the axis of rotation.

6. The probe device according to claim 5, wherein the first end segment and the second end segment are joined directly to each other or in which a cable conduit segment that extends along the axis of rotation joins the first end segment and the second end segment to each other.

7. The probe device according to claim 1, wherein the support arm is mounted in the manner of a one-sided or two-sided lever.

8. The probe device according to claim 1, further comprising: at least one counterweight, which is arranged on the support arm.

9. The probe device according to claim 1, wherein at least one probe device is configured and arranged in a rotating head.

10. The probe device according to claim 1, wherein at least one probe device is configured and arranged in a testing apparatus and/or wherein at least one probe device is configured and arranged in a testing apparatus having at least one rotating head.

11. The probe device according to claim 10, wherein at least one pair of probe devices, the probes of which are arranged facing each other, are configured and arranged in a testing apparatus.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0021] The invention will be explained below in detail on the basis of drawings. Herein:

[0022] FIG. 1 shows a rotating head in accordance with the prior art with two probe devices;

[0023] FIG. 2 shows a probe device in accordance with the prior art;

[0024] FIG. 3 shows a schematic side view of the probe device of FIG. 2;

[0025] FIG. 4 shows a schematic side view of a probe device according to the invention;

[0026] FIG. 5 shows a spatial depiction of a probe device according to the invention;

[0027] FIG. 6 shows a spatial depiction of a probe device with a cable conduit.

DESCRIPTION OF THE INVENTION

[0028] Depicted in FIG. 1 is a known circular rotating head 1 of a testing apparatus that is designed as a rotating system. The rotating head 1 has a central through-hole 2 and two essentially identically designed probe devices 3 and 4.

[0029] The probe device 3 can be seen enlarged in FIG. 2 and in a schematic side view in FIG. 3. It comprises two elongated support arms 5 and 6, which are arranged parallel with respect to each other and are joined to each other by an essentially centrally arranged middle connecting piece 7. At the level of the middle connecting piece 7, the support arms 5 and 6 are mounted so as to rotate as a kind of two-sided lever around an axis of rotation 8, which is drawn dashed in FIG. 2. A probe 9 that extends between the support arms 5 and 6 is held by the ends of the support arms 5 and 6 that face the through-hole 2, while a counterweight 10 is arranged at the end of the support arm 5 that faces away from the through-hole 2. Furthermore, the probe device 3 has a cable conduit with a first end segment 11 that extends starting from the probe 9 along the support arm 5 and a second end segment 12 that adjoins the first end segment 11, with the second end segment 12 neither intersecting the axis of rotation 8 nor starting from it. The cable conduit is provided for the mounting of a probe cable, which, for reasons of clarity, is not depicted in the figures. Finally, a coil tension spring or coil spring 13 engages at a point between the middle connecting piece 7 and the counterweight 10 on the support arm 5 and consequently at an end segment of the support arm 5 that faces away from the probe 9.

[0030] In terms of its construction, the probe device 4 corresponds essentially to the probe device 3. In particular, the probe device 4 also has a probe 14, which is fastened at end segments of its support arm. Provided at an end of a support arm of the probe device 4 opposite the probe is a counterweight 15. From the spatial perspective of FIG. 1, only the second end segment 16 of the cable conduit of the probe device 4 is visible. A coil spring 17 engages with one end at an end segment of the support arm of the probe device 4 that faces away from the probe 14 at a point between the second end segment 16 of the cable conduit and the counterweight 15 on the support arm.

[0031] In the rotating head 1, the two probe devices 3 and 4 are arranged in such a way that their respective probes 9 and 14 lie essentially diametrically opposite to each other with respect to the through-hole 2.

[0032] In the operation of the testing apparatus, one of the probes 9 and 14 is then inserted through the hole 2 toward the elongated test piece 18 to be inspected, while the rotating head 1 is rotated around the test piece 18. Through suitable choice of the counterweights 10 and 15 of the probe devices 3 and 4 as well as of the coil springs 13 and 17 on the probe devices 3 and 4, it is possible to adjust the contact pressure with which the probes 9 and 14 press against the surface of the test piece 18. The distance from the test piece 18 is adjusted in a contact-free method by mechanical delimitations of the angles of rotation, such as, for example, by the delimiter 36 depicted in FIG. 2 for the probe device 3. In the contact method, the delimiter 36 serves to hold back the support arm 5 in order that the path for the test piece 18 is not blocked. In contrast, the distance from the test piece 18 is influenced by the counterweight 10 and the coil spring 13 to the extent that, in the contact method, the probe 9 lifts from the test piece 18 or, in the contact-free method, the contact to the delimiter 36 is lost.

[0033] During the rotation of the rotating head 1, the coil springs 13 and 17 are subjected to centrifugal forces. These centrifugal forces influence the spring tensions of the coil springs 13 and 17 and thus the forces and torques exerted on the respective support arms by the coil springs 13 and 17. For this reason, the preadjusted distance of the probes 9 and 14 from the surface of the test piece 18 or the contact pressure thereof on the surface of the test piece 18 is influenced. Moreover, this influencing is dependent on the respective speed of rotation of the rotating head 1.

[0034] In order to prevent this influence of the centrifugal forces, a curved spring element instead of a coil spring is provided in the probe device 19, which is depicted in FIG. 4 in a schematic side view and in FIG. 5 in a spatial view. What is involved in the present case is a leg spring 20. As in the case of the previously described probe device 3, the probe device 19 also has support arms 21 for a probe 22, which are mounted so as to be able to rotate around the axis of rotation 8. A mount 23 for the leg spring 20 is provided on one of the support arms 21 in each case and is concentric with the axis of rotation 8. The leg spring 20 is arranged on the mount 23 and wound a plurality of times around the mount 23. By an end segment 24, the leg spring 20 rests against a projecting stop or stop pin 25 of the rotating head 1 and is thereby supported against it. In addition, the leg spring 20 engages at a point on the support arm 21 that is spaced apart from the axis of rotation 8, with it being fixed in place on the support arm 21 in this case by fastener 26.

[0035] As a result of the fact that end segment 24 of the leg spring 20 presses against the stop pin 25 and the fact that it is fixed in place by the fastener 26, through which it engages at the support arm 21, it is possible for the leg spring 20 to exert forces and torques on the support arm 21. In contrast, it is not possible during the operation of the rotating head 1 for arising centrifugal forces to increase the bending stress of the leg spring 20 and thereby to influence the forces and effected torques that act on the support arm 21 by way of the leg spring 20, because the leg spring 20 is arranged concentric with the axis of rotation 8. Instead of this, the leg spring 20 is pressed against the mount 23 by the centrifugal forces, without the bending stress thereof being influenced. For this reason, the contact pressure of the probe 22 against the surface of the test piece 18 or their distance from each other is also independent of the speed of rotation of the rotating head 1 and the diameter of the test piece 18.

[0036] When the rotating head 1 rotates, the probe cables, which are accommodated in the cable conduits of the known probe devices 3 and 4 and extend, after exiting from the second end segments 12 and 16 thereof, in an arc shape up to a connection terminal or inlet of the rotating head 1, experience centrifugal forces. These centrifugal forces, in turn, exert a lever effect on the rotatably mounted probe devices 3 and 4, as a result of which the preadjusted distance of the probes 9 and 14 from the surface of the test piece 18 or the contact pressure thereof on the surface of the test piece 18 is influenced.

[0037] FIG. 6 shows a probe device 27 for which this problem, too, is surmounted. In contrast to the above-described known probe devices 3 and 4, the probe device 27 comprises two support arms 28 and 29, which are designed as a one-piece component. The two support arms 28 and 29 are mounted so as to be able to rotate around the same axis of rotation, with the rotation thereof being influenced by a leg spring 30 in the way described above. Held at an end of the support arms 28 and 29 is a probe 31, which extends between the support arms 28 and 29, while, at the end of the support arm 29 lying opposite to it, a counterweight 32 is arranged.

[0038] The probe device 27 differs from the previously described probe devices 3 and 4 not only in terms of the one-piece design of the support arms 28 and 29, but also in terms of its cable conduit for the mounting of probe cables. Thus, the cable conduit of the probe device 27 has a first end segment 33 that extends along the support arm 28 from the probe 31 to the axis of rotation. A second end segment 34 extends essentially from the axis of rotation or encloses an angle with it. The first end segment 33 and the second end segment 34 are joined by a cable conduit segment 35, which is designed as a hollow shaft and extends along the axis of rotation. In the installed state of the probe device 27 in the rotating head 1, the second end segment 34 is arranged permanently or detachably in relation to the rotating head 1, while the support arms 28 and 29 can rotate around the axis of rotation and thus can make a rotational movement in relation to the second end segment 34. Inside of the hollow cable conduit segment 35, it is possible for a probe cable to twist flexibly when the support arms 28 and 29 are tilted, without its position or its distance being changed significantly. Provided on the support arm 29 is a cable conduit that corresponds to the cable conduit of the support arm 28.

[0039] As a result of the special cable conduit with the first end segment 33 running up to the axis of rotation, the second end segment 34 starting from the axis of rotation, and the cable conduit segment 35 being parallel to the axis of rotation, a probe cable can be guided in such a way that, when the rotating head 1 rotates, it is possible to minimize the influence of the centrifugal force on the probe device 27. In particular, in the case of the probe device 27, no cable bends whatsoever arise, which would be subjected to a centrifugal force of this kind and would transmit this centrifugal force to the support arms 28 and 29. When, for example, the support arm 28 rotates around the axis of rotation, the probe cable can freely twist inside of the hollow cable conduit segment 35, without changing its shape or becoming distant from the axis of rotation, so that it cannot exert any forces due to the rotation of the rotating head 1 on the probe device 27. Accordingly, the probe device 27 can be balanced a single time by way of the counterweight 32 in accordance with the weight of the probe 31. The probe device 27 that has been balanced then functions uniformly over the entire range of diameter and range of rotational speeds of the rotating head 1. Accordingly, the contact pressure on the test piece 18 or the distance of the probe 31 from the surface thereof is independent of the centrifugal force.

[0040] In another embodiment of a probe device according to the invention, a hollow cable conduit segment is dispensed with and the first end segment is joined to the second end segment directly.

[0041] It would be appreciated by those skilled in the art that various changes and modifications can be made to the illustrated embodiments without departing from the spirit of the present invention. All such modifications and changes are intended to be covered by the appended claims.