Probe with curved spring, rotating head and tester

Abstract

The invention relates to a probe (19, 27) for a rotary head (1), comprising at least one support arm (21, 28, 29) mounted rotatably about a rotary axis (8), at least one probe head (22, 31) coupled to the support arm (21, 28, 29), and at least one spring element (20, 30) which can be supported on the rotary head (1) and acts on the support arm (21, 28, 29), the spring element being designed to exert a force on the support arm (21, 28, 29), the support arm being subjected to a torque relative to the rotary axis (8) as a result of the force. The support arm (21, 28, 29) has at least one receptacle (23) for the spring element (20, 30) which is concentric with the rotary axis (8), the spring element being at least partially curved about the rotary axis (8) when it is seated in the receptacle (23). As a result, the centrifugal force acting on the spring element (20, 30) during operation of the rotary head (1) has no effect on the tensioning of the spring element (20, 30).

Description

Technical Field

[0001] This invention relates to a detector for a rotating head, comprising at least one support arm rotatably mounted about a rotation axis, at least one probe connected to the support arm, and at least one spring member supported on the rotating head and acting on the support arm, the spring member being configured to apply a force to the support arm, the support arm being subjected to a torque associated with the rotation axis due to said force. The invention also relates to a rotating head having at least one such detector and a testing instrument having at least one such detector and / or at least one such rotating head. Background Technology

[0002] In particular, to inspect rod-shaped, round metal semi-finished products for defects such as cracks and shrinkage cavities using eddy current or magnetic flux leakage methods, a test instrument designed with a rotary system is employed. In such a rotary system, the detector is mounted on a rotatable head of the test instrument. Because the rotating head, along with the detector mounted on it, rotates as the elongated test piece is moved through a central through-hole, the detector moves relative to the test piece along a helical trajectory. To measure the magnetic field changes caused by defects in the test piece, the probe, pre-set for the eddy current method, must be positioned at a predetermined distance or as close as possible to the surface of the test piece. In the magnetic flux leakage method, the probe contacts the test piece and scratches its surface. Here, they wear out and must be replaced periodically. Therefore, the pressure exerted by the probe on the surface of the test piece should be as small as possible, and the probe should not be lifted off the test piece, as lifting the probe would interfere with or even hinder the test.

[0003] Therefore, DE102012108241A1 discloses a detector or probe carrier for a tester in the form of a rotating system for non-destructive testing of elongated test pieces using leakage flux or eddy currents. The probe carrier is designed to be modular and insertable, thereby enabling rapid adaptation of the tester to varying test piece diameters.

[0004] Other known detectors, such as the one shown in DE102015214232A1, have a support arm that is freely movable about a center of rotation. A probe is positioned at one end of the support arm, which is mounted in a double-arm lever configuration, and a counterweight is positioned at the opposite end of the support arm. A force and, consequently, a torque are induced on the support arm by means of a tension spring acting on the support arm and mounted on the rotating head. If the workpiece under test moves, for example, randomly through a through-hole in the rotating head, the probe can be accordingly avoided due to the rotatable mounting of the support arm supporting it. By means of the counterweight and the tension spring acting on the support arm, the probe position and, perhaps, the clamping force of the probe on the workpiece can be adjusted at a predetermined distance from the surface of the workpiece, depending on a predetermined rotating head speed and a predetermined diameter of the workpiece.

[0005] During the rotation of the rotating head, the spring element encounters centrifugal force. Depending on the rotational speed of the rotating head and the position of the support arm, the force exerted by the spring element on the support arm varies, consequently affecting the torque acting on the support arm around the rotation axis. This, in particular, affects the clamping force or position of the probe relative to the test piece. If the clamping force exerted by the probe on the test piece increases, probe wear becomes severe. Conversely, if the clamping force decreases, depending on whether the test is a leakage magnetic field method or an eddy current method, the probe may lift off the test piece or increase its distance from the test piece, thus interfering with or making the test impossible.

[0006] To prevent the probe from lifting off the test surface and thus interrupting the test process in the magnetic flux leakage method under conditions of large test pieces and corresponding rotating head speeds, there is a tendency to design the spring force and consequently the clamping force of the probe on the test piece to be too high, or to reduce the rotating head speed. However, high clamping forces lead to severe wear of the probe rubbing against the test piece surface, while reduced rotating head speeds result in reduced flow through the test piece. In practice, the precise adjustment of the probe distance from the test piece surface in the eddy current method also becomes quite difficult due to the influence of the rotational speed and the diameter of the test piece. Summary of the Invention

[0007] Therefore, the objective of this invention is to provide a detector, a rotating head, and a test instrument that allow the probe to be adjusted about the test piece independently of centrifugal force.

[0008] The task is accomplished by a detector having the features of claim 1, a rotating head having the features of claim 9, and a tester having the features of claim 10.

[0009] In known detectors, the spring is mostly designed as a tension spring that acts on a support arm at a location spaced apart from the axis of rotation, causing the clamping force of the probe on the test piece to vary with the rotational speed of the rotating head or the diameter of the test piece. In the detector of this invention, the support arm has at least one housing for the spring, concentric with the axis of rotation. When arranged on the housing, the spring is at least partially bent about the axis of rotation. In other words, the axis of rotation is at least partially wound around the spring, or the spring is at least partially wound or coiled around the axis of rotation. Here, the spring can be wound around the housing or axis of rotation at least one or more turns, or coiled around the housing or axis of rotation once or more. Here, the spring, bent or coiled about the axis of rotation, acts on a location on the support arm spaced apart from the axis of rotation. This location can be located on the housing, but it can also be spaced apart from the housing.

[0010] More commonly, the support arm can have a longitudinal axis, wherein the longitudinal axis and the rotation axis can be obliquely aligned. However, the support arm or its longitudinal axis can also intersect the rotation axis. Furthermore, the probe can be fixed to the ends of two or more parallel support arms, all of which are rotatably mounted about the same rotation axis. Additionally, at least one counterweight can be provided on the support arm for adjusting the probe's clamping force or position; its position is advantageously adjustable along the support arm.

[0011] Because the spring is bent or coiled around a housing concentric with the axis of rotation and thus also around the axis of rotation, it is pressed against the housing under centrifugal force without generating bending stress within the spring. Therefore, the spring does not exert a force on the support arm caused by centrifugal force, thus preventing torque on the support arm. Instead, the support arm remains balanced for any rotational speed of the rotating head and any diameter of the workpiece. Even at high rotational speeds, the probe must not be lifted or detached from the workpiece. Furthermore, because there is always an optimal or minimal clamping force, probe wear is reduced, significantly extending probe life and maintenance intervals. Since the probe clamping pressure is generated solely by spring force and the support arm only needs to be balanced once, for example, with a suitable counterweight, the need for reprocessing the counterweight to adjust the probe clamping force acting on the workpiece surface or the distance between the probe and the workpiece surface is eliminated. Such post-adjustment of the counterweight is only necessary when using probes with varying weights. In particular, the productivity of the test apparatus with the detector of the present invention is also improved because the counterweight no longer needs to be adjusted in relation to the diameter or even the linear speed no longer needs to be forcibly reduced, since the required rotational speed of the rotating head can always be achieved.

[0012] Springs can be particularly flexible springs, such as helical springs, elliptical springs, parabolic springs, wave springs, wire springs, or helical torsion springs. The following are generally referred to as flexible springs: they can generate bending stress within the object through elastic deformation under bending moment. Examples of flexible springs include helical springs, which are strongly bent metal strips wound in a helical pattern within a plane. Elliptical springs consist of slightly bent leaf springs, often mounted in pairs as stacks of multiple overlapping individual leaf springs. Parabolic springs use leaf springs with a thickness that decreases parabolically from the center towards both ends, instead of stepped spring stacks. Wave springs are loops made of flat, wave-shaped metal wires, where the wave bends outward under stress. Wave springs can be stacked or mounted as a single layer. Unlike leaf springs with rectangular cross-sections, wire springs are made of metal wire. Wire springs include, in particular, helical torsion springs, which are helically wound or bent wire springs with protruding straight ends or legs for transmitting torque to the bent wire.

[0013] In principle, the spring can be fixedly or detachably connected to the support arm, or it can be fixed to it. Accordingly, the spring can thus be supported on the rotating head, so that it is fixedly or detachably connected to it at a suitable location on the rotating head or at an element of the rotating member. However, a preferred detector embodiment is one in which the spring is not connected to the rotating head, but instead has a support portion, for example, one end for supporting or abutting against a stop on the rotating head. Such an embodiment has the particular advantage of allowing for the simple replacement of individual springs, and the replacement of the support arm or even the entire detector when the spring is not mounted on the support arm or its housing, or when the spring is fixedly or movably mounted on the support arm, without having to loosen or detach the spring from the rotating head. Installing a new spring, support arm, or detector is also simple.

[0014] The detector of this invention is applicable to any rotating system, specifically to rotating systems in which the probe is movably suspended on a support arm. For non-contact testing methods, a mechanical cornering mechanism can also be provided for the support arm and / or the probe, which rests against the cornering mechanism with slight pressure, allowing it to be avoided as easily as possible. This reduces the collision energy of the test piece colliding with the probe's deflection mechanism.

[0015] Because the detector probe needs to be connected to the analysis unit in order to transmit measurement signals, for example, the probe cable extends from the probe through the support arm. The probe cable typically extends from an interface or inlet end of the rotating head to the detector in the form of a cable bend or loop and is guided to the probe via the detector's support arm within a cable guiding mechanism to ensure the mobility of the support arm. Like the springs of known detectors, the cable bend is subjected to centrifugal force during the rotation of the rotating head, thereby exerting torque on the support arm, which in turn affects the clamping force or position of the probe associated with the test piece.

[0016] To reduce or avoid such torque, the detector preferably has at least one cable guiding mechanism for guiding the probe cable, wherein the cable guiding mechanism has a first end extending along the support arm from the probe to the rotation axis and a second end substantially from the rotation axis. In other words, both the first and second ends are substantially abutting the rotation axis at one end, or each end is substantially positioned at the rotation axis, or each end is at the height of the rotation axis. The first and second ends thus form an angle with the rotation axis. This results in a probe cable being supplied to or from the detector or its probe at the height of the rotation axis of the support arm. Therefore, when the detector and probe cable are both rotated as part of the rotating head of the rotary system and subjected to centrifugal force, the probe cable will never cause torque acting on the support arm. Therefore, the probe cable will never affect the adjustment of the probe position or the clamping force acting on the surface of the workpiece.

[0017] The following detector implementation is feasible, in which the first end and the second end are directly connected to each other. In these cases, the two ends essentially meet at the rotation center of the support arm. In other implementations of the detector, a cable guide extending along the rotation axis connects the first end and the second end. For example, the first end may extend probe-to-the-rotation axis or the rotation center of the support arm, where a cable guide parallel to the rotation axis enters, and the cable guide extends along the rotation axis away from the rotation center of the support arm and then enters the second end.

[0018] In the detector of the present invention, the support arm can be mounted in the form of a single-arm lever or a double-arm lever. In both cases, the probe can be connected to the support arm at one end or one end. If the support arm is mounted in the form of a double-arm lever, it is preferable to mount at least one counterweight on the support arm outside the probe, wherein the probe and the counterweight are located on opposite sides of the axis of rotation of the support arm about opposite ends of the support arm, specifically preferably at opposite ends or ends of the support arm.

[0019] The rotating head of the present invention advantageously has at least one detector of the present invention. By appropriately selecting the spring constant of the spring element, it is possible to adjust the position of the probe relative to the test piece or the clamping force of the probe against the test piece.

[0020] The tester according to the invention preferably has at least one pair of detectors, with the probes of the detectors arranged facing each other. If the test piece is arranged between or passes through the probes, the probes can simultaneously examine the opposing sides of the test piece. Attached Figure Description

[0021] The present invention will now be described in detail with reference to the accompanying drawings, wherein:

[0022] Figure 1 A rotating head with two detectors according to the prior art is shown;

[0023] Figure 2 This illustrates a detector based on existing technology;

[0024] Figure 3 Show Figure 2 A side view of the detector;

[0025] Figure 4 A side view schematic diagram of the detector of the present invention is shown;

[0026] Figure 5 A perspective view of the detector of the present invention is shown;

[0027] Figure 6 A perspective view of a detector with a cable guiding mechanism is shown.

[0028] List of reference numerals

[0029] 1. Rotating head; 2. Through hole; 3. Detector; 4. Detector; 5. Support arm; 6. Support arm; 7. Intermediate web; 8. Rotation axis; 9. Probe; 10. Counterweight; 11. First end; 12. Second end; 13. Helical spring; 14. Probe; 15. Counterweight; 16. Second end; 17. Helical spring; 18. Test piece; 19. Detector; 20. Helical torsion spring; 21. Support arm; 22. Probe; 23. Receptacle; 24. End; 25. Stop pin; 26. Fixing mechanism; 27. Detector; 28. Support arm; 29. ​​Support arm; 30. Helical torsion spring; 31. Probe; 32. Counterweight; 33. First end; 34. Second end; 35. Cable guide; 36. Limiting element. Detailed Implementation

[0030] exist Figure 1 The diagram shows a known circular rotating head 1 of a test instrument configured as a rotating system. The rotating head 1 has a central through-hole 2 and two detectors 3 and 4 with essentially identical configurations.

[0031] exist Figure 2 Enlarged and shown in Figure 3 The detector 3 can be seen in the side view diagram. It includes two elongated support arms 5 and 6, which are arranged parallel to each other and connected to each other by a centrally located intermediate web 7. At the height of the intermediate web 7, the support arms 5 and 6 can be wound around the detector in the form of a double-arm lever. Figure 2The rotation axis 8, indicated by dashed lines, is rotatably mounted. The probe 9, extending between support arms 5 and 6, is held at the end of support arms 5 and 6 facing the through hole 2, while a counterweight 10 is provided at the end of support arm 5 opposite to the through hole 2. Furthermore, the detector 3 has a cable guiding mechanism comprising a first end 11 extending along support arm 5 from probe 9 and a second end 12 connected to the first end 11, wherein the second end 12 neither intersects with nor extends from the rotation axis 8. The cable guiding mechanism is configured to accommodate the probe cable, which is not shown in the figure for overview purposes. Finally, a helical tension spring or helical spring 13 acts on a portion of support arm 5 between the intermediate web 7 and the counterweight 10, thus acting on the end of support arm 5 opposite to probe 9.

[0032] The structure of detector 4 is basically the same as that of detector 3. In particular, detector 4 also has a probe 14 fixed to the end of its support arm. A counterweight 15 is provided at the end of the support arm of detector 4 opposite to the probe 14. Figure 1 From the spatial perspective, only the second end 16 of the cable guiding mechanism of detector 4 is visible. The helical spring 17 acts at a point between the second end 16 of the cable guiding mechanism and the counterweight 15 on the support arm of detector 4, with one end at the end opposite to the probe 14.

[0033] The two detectors 3 and 4 are arranged inside the rotating head 1 such that their respective probes 9 and 14 are basically radially opposed about the through hole 2.

[0034] Now, during the operation of the tester, an elongated test piece 18 to be tested by probes 9 and 14 is moved through the through hole 2, at which point the rotating head 1 rotates around the test piece 18. By appropriately selecting the counterweights 10 and 15 of the detectors 3 and 4, and the helical springs 13 and 17 acting on the detectors 3 and 4, the clamping force that presses probes 9 and 14 onto the surface of the test piece 18 can be adjusted. The distance from the test piece 18 can be controlled in non-contact methods by means of mechanical angular limiting elements, such as those used in... Figure 2 The limiting member 36 shown for the detector 3 is adjusted. In the contact method, the limiting member 36 is used to block the support arm 5 so as not to lock the path for the test piece 18. The distance from the test piece 18 is affected by the counterweight 10 and the coil spring 13 as described below, that is, the probe 9 is lifted away from the test piece 18 in the contact method, or in other words, it loses contact with the limiting member 36 in the non-contact method.

[0035] During the rotation of the rotating head 1, helical springs 13 and 17 encounter centrifugal force. This centrifugal force affects the tension of the helical springs 13 and 17, which in turn affects the force and torque applied by the helical springs 13 and 17 to their respective support arms. Therefore, the preset distance of probes 9 and 14 from the surface of the workpiece 18, or the clamping force exerted on the surface of the workpiece 18, is affected. This effect is also related to the respective rotational speed of the rotating head 1.

[0036] To avoid the effects of centrifugal force, in such Figure 4 In the side view diagram and in Figure 5 In the detector 19 shown from a three-dimensional perspective, a curved spring element is provided instead of a helical spring. This is a helical torsion spring 20. Like the aforementioned detector 3, detector 19 also has a support arm 21 for the probe 22, rotatably mounted about the rotation axis 8. A housing 23 for the helical torsion spring 20 is concentrically disposed on one of the support arms 21 with respect to the rotation axis 8. The helical torsion spring 20 is mounted on the housing 23 and wound around it multiple times. One end 24 of the helical torsion spring 20 abuts against and is supported on a protruding stop or retaining pin 25 of the rotating head 1. Furthermore, the helical torsion spring 20 acts on a portion of the support arm 21 spaced from the rotation axis 8, where it is currently fixed to the support arm 21 by means of a fixing mechanism 26.

[0037] Because the end 24 of the helical torsion spring 20 presses against the stop pin 25 and is fixed by means of the fixing mechanism 26 that acts on the support arm 21, the helical torsion spring 20 can apply force and torque to the support arm 21. The centrifugal force generated during the operation of the rotating head 1 does not increase the bending stress of the helical torsion spring 20 and thus affect the force and torque acting on the support arm 21 through the helical torsion spring 20, because the helical torsion spring 20 is arranged concentrically with the rotation axis 8. Instead, the helical torsion spring 20 is pressed against the housing 23 by centrifugal force, which does not affect its bending stress. Therefore, the clamping force of the probe 22 against the surface of the workpiece 18, or the distance between them, is independent of the rotational speed of the rotating head 1 and the diameter of the workpiece 18.

[0038] When the rotating head 1 rotates, the probe cables housed in the cable guiding mechanisms of the known detectors 3 and 4, and extending in an arc from their second ends 12 and 16 to the interface or inlet end of the rotating head 1, are also subjected to centrifugal force. This centrifugal force then exerts a lever effect on the rotatably mounted detectors 3 and 4, thereby affecting the preset distance of probes 9 and 14 from the surface of the test piece 18 or the clamping force they exert on the surface of the test piece 18.

[0039] Now, Figure 6A detector 27 is shown, which also overcomes the aforementioned problems. Unlike the known detectors 3 and 4 described above, detector 27 includes two support arms 28 and 29, which are designed as a single integral component. The two support arms 28 and 29 are rotatably mounted about the same axis of rotation, where their rotation is influenced by a helical torsion spring 30 as described above. A probe 31, extending between the support arms 28 and 29, is held at one end of the support arms 28 and 29, while a counterweight 32 is disposed at the end of the support arm 29 opposite to the probe.

[0040] The difference between detector 27 and the aforementioned detectors 3 and 4 lies not only in the integrated design of support arms 28 and 29, but also in its cable guiding mechanism for accommodating the probe cable. For this purpose, the cable guiding mechanism of detector 27 has a first end 33 extending along the support arm 28 from the probe 31 to the rotation axis. A second end 34 extends substantially from the rotation axis or forms an angle with it. The first end 33 and the second end 34 are interconnected by a cable guide portion 35 extending along the rotation axis in a hollow shaft shape. When detector 27 is installed within the rotating head 1, the second end 34 is fixed or immovably positioned relative to the rotating head 1, while the support arms 28 and 29 can rotate about the rotation axis and therefore can rotate relative to the second end 34. Within the hollow cable guide portion 35, the probe cable can be flexibly twisted when the support arms 28 and 29 are tilted without significantly changing its position or distance relative to the rotation axis. A cable guiding mechanism corresponding to the cable guiding mechanism of the support arm 28 is provided on the support arm 29.

[0041] Because of this special cable guiding mechanism, which has a first end 33 leading to the rotation axis, a second end 34 starting from the rotation axis, and a cable guide 35 parallel to the rotation axis, the probe cable can be guided in such a way that the effect of centrifugal force on the detector 27 can be minimized when the rotating head 1 rotates. In particular, no cable bends are likely to occur in the detector 27, which would be subject to centrifugal force and transmit it to the support arms 28, 29. When, for example, the support arm 28 rotates about the rotation axis, the probe cable can freely twist within the hollow cable guide 35 without changing its shape or leaving the rotation axis, thus preventing the rotation of the rotating head 1 from exerting force on the detector 27. Therefore, the detector 27 can be balanced once by the counterweight 32, corresponding to the weight of the probe 31. Thus, the balanced detector 27 functions identically across the entire diameter and rotational speed range of the rotating head 1. Therefore, the clamping force acting on the test piece 18, or the distance of the probe 31 from its surface, is independent of the centrifugal force.

[0042] In another embodiment of the detector of the present invention, the hollow cable guide is discarded, and the first end is directly connected to the second end.

Claims

1. A probe (19, 27) for a rotary head (1), having at least one bearing arm (21, 28, 29) mounted rotatably about a rotary axis (8), at least one probe head (22, 31) coupled to the bearing arm (21, 28, 29), and at least one spring element (20, 30) which can be supported on the rotary head (1) and acts on the bearing arm (21, 28, 29), the spring element being provided for exerting a force on the bearing arm (21, 28, 29), the bearing arm being subjected to a torque relative to the rotary axis (8) as a result of the force, the bearing arm (21, 28, 29) having at least one receptacle (23) for the spring element (20, 30) which is concentric with the rotary axis (8), the spring element being at least partially curved about the rotary axis (8) when seated in the receptacle (23), the bearing arm (21, 28, 29) being mounted in the form of a double-armed lever for rotation about the rotary axis (8), the spring element being able to be wound in at least one or more turns around the receptacle or rotary axis. The spring element (20, 30) is a bending spring or a helical spring or an elliptical spring or a parabolic spring or a wave spring or a wire spring or a helical torsion spring. The spring element (20, 30) has a bearing portion (24) for bearing against a stop (25) of the rotary head (1). The probe has at least one mechanical angle limit mechanism (36) for the bearing arm (21, 28, 29) and / or the probe head (22, 31). wherein The probe has at least one cable guide mechanism for guiding a probe head cable, wherein the cable guide mechanism has a first end portion (33) which extends along the bearing arm (21, 28, 29) from the probe head (22, 31) to the rotary axis and a second end portion (34) which extends from the rotary axis. The first end portion (33) and the second end portion (34) are coupled directly to one another or a cable guide portion (35) which extends along the rotary axis couples the first end portion (33) and the second end portion (34) to one another. It has at least one counterweight (32) seated on the bearing arm (21, 28, 29).

2. The probe (19, 27) as claimed in claim 1, characterized in that 8. A rotary head (1) having at least one probe (19, 27) according to any one of claims 1 to 7.

3. The probe (19, 27) as claimed in claim 1, characterized in that 9. A testing instrument having at least one probe (19, 27) according to any one of claims 1 to 7 and / or at least one rotary head (1) according to claim 8.

4. The probe (19, 27) according to any one of claims 1 to 3, characterized in that It has at least one pair of probes (19, 27), the probe heads (22, 31) of which are arranged facing one another.

5. The probe (19, 27) according to any one of claims 1 to 3, characterized in that ​ 6. A probe (19, 27) as claimed in claim 5, characterized in that ​ 7. The probe (19, 27) according to any one of claims 1 to 3, characterized in that ​ ​ ​ 10. The tester of claim 9 wherein, ​

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