DE7533531U - DIVISIBLE COIL ARRANGEMENT FOR THE GENERATION OF A MAGNETIC FIELD IN A LONGITUDINAL DUTY - Google Patents

Description

The invention relates to a divisible coil arrangement, in particular for the non-destructive testing of the alternating current Coil traversing parts, with changes in impedance occurring as a result of Defects in the material characteristics of the parts, such as an inhomogeneity of the material, which leads to changes in magnetic permeability and electrical conductivity, which result from Changes in the strength of the Foucault currents that occur as the parts move through the coil are transmitted .

Are the parts to be tested such, the dimensions of which are relatively large, or those that take the form of a rod or a metallic cable.

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have, the ends of which are inaccessible or the ends of which have thickenings, the diameter of which is far larger is, as the parts' which lie between the ends, then you cannot use coils of the type mentioned above, since it is not possible to put the parts to be measured into the coil to introduce.

In order to be able to check such parts for errors, it is known to use divisible coils. Such coils, however are traversed by a direct current of great strength and generate a magnetic field, which changes as a result of defects in the material of the parts to be tested can be measured in a measuring coil, which is from the excitation coil is independent. However, only ferromagnetic Parts are checked and only if a Relative displacement between the coil and the part to be tested is present.

The object is to design a coil of the type mentioned in such a way that it is divisible and instead of a direct current flowed through by an alternating current can be.

The coil according to the hiring is only with alternating current fed, whereby the changes in the intensity of the Foucault currents occurring in the test object are detected. This is preferably done with an alternating current fed at a frequency between 1 and 100 kHz. With such a coil elongated test objects can be made electrically conductive material can be tested non-destructively, whereby the test items are not made of a ferromagnetic material need to exist.

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UtL.

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For the test it is not necessary that a relative shift exists between the coil and the test item.

The coil according to the innovation is divisible and can be on this Way around the test item to be tested, whereby the coil parts are then connected to one another, so that the bobbin surrounds the test object. The assembly of the coil parts is done in such a way that automatically result in coil turns from conductor wire without it being necessary to pass the coil turns to interconnect a plurality of external connecting means. Rather, the coil turns form two turns Coils, which are separated from each other.

For this purpose, the coil according to the invention has a tubular coil body which extends in the longitudinal direction is divided, so that there are several elements that can be combined with one another. Oedes of these bobbin elements carries coil winding segments from a conductor wire, which are in transverse planes essentially from a cut or Extend the dividing edge to the adjacent cutting or dividing edge. These segments are divided into two groups of equal segments which form two separate coils. The ends of the segments of one group are continuous with the corresponding ends of the segments of the other group by ladder connected, which run along the cutting or dividing edge which is adjacent to the respective ends. The spiral segments on each bobbin have two free wire segment ends, which have a detachable

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Connection with the corresponding free wire segment ends of the other bobbin elements are connected, with the exception a segment end on two elements of the coil body elements to form a current input and output for the two coils connected in series. The two spaced apart coils are with respect to their lines on each of the two coils are switched so that the current in all conductor segments is the same Direction flows.

As a result of this special construction, a double coil can be placed around every elongated test object whose ends are inaccessible arrange. The active coil windings are formed by the transverse winding parts while the longitudinal parts of the winding, the aforementioned connect transverse winding parts with each other, are inactive. This is caused by the fact that half of these inactive parts of the winding are from a current in one direction and the other half of these winding parts are traversed by a current in the opposite direction, so that the entirety of these longitudinal winding parts produces a field which is equal to zero. The number the external connections, except for the input and output connection of the coil, is reduced to a minimum. If the bobbin is divided into two parts, then the number of these external connections is on a single connection reduced, with this connection the ends of the two Winding segments which are arranged on the two bobbin elements are connected to one another.

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The double coil according to the innovation forms one in itself Measuring unit which is equivalent to two coils connected in series and surrounding the test object. These two An alternating current flows through coils in the opposite sense at every moment. The two coils are spaced from each other in such a way that a mutual influence is opposed to the generated directed magnetic fields is prevented.

According to an advantageous embodiment, the bobbins are perelements connected to one another by means of removable fastening means, such that one unit is formed as if the bobbin from a single rigid part.

The following is an embodiment of the innovation according to the invention Subject explained with reference to the drawings. Show it:

Fig. 1 is a longitudinal section along the line I-I

in Fig. 2 by a divisible electrical coil, the coil body of two elements consists;

FIG. 2 shows an end view of the coil according to FIG. 1; FIG.

3 shows a schematic perspective illustration of the arrangement of the conductor wires in a coil according to Figures 1 and 2;

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FIG. K shows a schematic perspective illustration of an embodiment which differs from FIG. 3; FIG.

FIG. 5 shows a development of the coil arrangement according to FIG.

6 shows a section through a coil with two asymmetrical coil arrangements;

7 shows a schematic perspective illustration through a coil for a differential Measurement;

8 shows a development of the coil according to FIGS. 7 and

9 shows a section through a focusing coil.

The divisible electrical coil shown in FIGS. 1 and 2 has a tubular bobbin 1 which is divided into several elements 3, ^ by a longitudinal gap 2 which extends over the entire length of the bobbin 1. In the illustrated embodiment, it is a diametrically extending slot 2, so that only two Spulenkorperelemente 3, k arise.

Each of these two coil body elements consists of one semi-cylindrical part 5, at both ends of which one each Flange 7, 8 fastened by means of screws 9, for example

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is. In the example shown, the flanges 7, 8 are rectangular, with a connection plane, which is with the connection plane of the two semi-cylindrical elements 5 of the bobbin coincides. Each flange half has a semicircular recess 11, 12 which corresponds to the recesses of the semicylindrical elements 5.

In each of the two semi-cylindrical elements 5 of the bobbin two grooves 21, 22 are provided in which the turn segments are arranged from conductor wire, which extend essentially over a semicircle. The number of these winding segments can be according to one desired value and set according to the wire thickness, while the dimensions of the section of the annular Grooves 21 and 22 are determined depending on the characteristics which the coil is to have.

For the sake of clarity, FIG. 3 only shows two turn segments shown for each groove. In the In the groove 21 there are two winding segments 25 and 26, while the winding segments 27 and 28 are arranged in the groove 22 are. One end A of the winding segment 25, which is arranged in the first groove 21, forms the input connection of the resulting coil, while the other end B via a longitudinal conductor 31 to end C of the winding segment 27, which is arranged in the second groove 22. The longitudinal conductor 31 runs substantially near the edge of the bobbin member near the connection plane 2 in a recess The other end D of the turn segment 27 is about a further longitudinal conductor 32 with the end E of the

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Winding segment 26 connected in the first groove 21. The longitudinal conductor 32 extends near the edge of the coil body element and is arranged in a recess 30 A. The other end F of the winding segment 26 is connected to the end G of the winding segment 28 via a further longitudinal conductor 33 which is parallel to the longitudinal conductor 31 is arranged in the same recess 30. Ultimately, the other end H of the winding segment 28 is led to the outside and is connected to the end 3 of a winding segment 28 A which corresponds to the winding segment 28 and which is carried by the other half of the bobbin.

In the lower half of Fig. 3, the part of the conductor wires is shown schematically, which on the other half of the bobbin is arranged, the arrangement of the segments of the conductor wire of those on the first coil half corresponds to and where corresponding parts are provided with the additional letter A.

The free end S of the winding segment A in the first groove forms the exit of the coil.

The segment ends H and 0 are connected to one another via an easily detachable connection 41, for example can be a plug connection.

Including the two halves of the bobbin as shown in Fig. 2, are connected to each other, the turn segments 25, 23 A and 26, 26 A work together so that they are in the first groove 21 form two complete turns, in an analogous manner the turn segments 27, 27 A and 28, 28 A to-

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together two complete turns in the second slot 22. If a current enters the coil at point A and at Point S exits, then this current flows in all winding segments that are arranged in the first groove 21, in the same direction. The same applies to the winding segments that are arranged in the second groove 22, however, the direction of the current is exactly the opposite of that here of the winding segments in the first groove 21. The flow in the two longitudinal conductors 31 and 33 Current in each case has a direction which is opposite to the direction of current in the longitudinal ones Conductors 31A and 33A, these conductors being practically close together when the coil is assembled. The same applies to the two longitudinal ones adjacent conductors 32 and 32A. It follows that the effects of the flowing in the longitudinal conductors Current cancel each other, which leads to the fact that the assembled coil practically from one arranged in the slot 21 Coil and a further coil arranged in the groove 22, both coils having the same current, however with the opposite direction of flow .

The distance between the two grooves 21 and 22 is chosen to be sufficiently large so that the induced in a test object Foucault currents do not influence one another. The examinee is pushed into the recess formed by the bobbin.

For use, the two halves of the bobbin are separated after the connection 41 has been removed and then the two coil halves are placed around the test item, for example

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wise arranged around a rod kO . The two coil halves are then connected to one another along the connecting plane 2 and finally the connection 41 is reattached, after which the input connection A and the output connection S are connected to an alternating current source and a measuring device. The coil serves to transmit the alternating current to generate a Foucault current and, on the other hand, to measure any impedance changes in the coil as a result of errors in the test object.

As an alternative to this, the same bobbin elements can be used arrange further groups of winding segments, for example two further groups, the first two groups serving to generate Foucault currents to be fed with an alternating current while the two other groups are connected to a measuring device and are used to acquire signals.

In order to facilitate the handling of the reel, the two reel halves can be connected with easily detachable connecting means be provided.

It is not necessary that the bobbin be cylindrical is trained. It can be any other desired shape, for example, a prismatic shape.

The embodiment according to FIGS. 4 and 5 differs differs from the embodiment according to FIG. 3 only in that that the connection of the ends of the two winding segments runs between the two points M and N at the level of the input and output connections A and S

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Place the connection between ends H and 0 shown in FIG. 3. For this purpose, two additional longitudinal conductors 37 and 37A are provided, one connecting point H to point M and the other connecting point 3 to point N The operation of the coil is not influenced by this, since the number of longitudinal conductors through which the current flows in one direction is always equal to the number of longitudinal conductors through which a current flows in the opposite direction.

Those previously described and shown in FIGS. 3 and 4 Coils can each be viewed as a simple probe with a dual function, that is, the same The coil is used to generate an alternating magnetic field and to measure the effects of the induced Currents. The measurements of the impedance correspond to those of two simple coils and the information obtained represent a composite of information obtained from the two sections of the specimen can be obtained.

The two coil parts 25, 25A, 26, 26A on the one hand and 27, 27A, 28, 8A on the other hand, can be of identical design, as can be seen from FIGS. 3 and k. However, it can prove to be advantageous to give these two coils a different geometry, as is shown schematically in FIG. 6, only the active parts of the respective coil being shown in this figure and the longitudinal connecting conductors being omitted. Since the two asymmetrical coils are shifted over the test object at the same time,

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is obtained to locate an error. information

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of different duration and amplitude.

In the case of a simple probe with a double function, which can be divided into two parts and as shown in FIGS. 3 to 4 and 6 , the two parts that can be dismantled from one another are only connected via a single external connection point (connection HJ or MN), independent

on the number of turns of the coils. i

In the aforementioned case of a probe with separate functions, that is to say with a first coil arrangement made up of two Coils through which alternating current flows and a j

second coil arrangement of two coils, which is used for signal measurement, the two coil arrangements with their respective winding segments on the same bobbin

elements be arranged. In this case and where the coil j is separable into two parts, the two are connectable to each other Parts are only connected to one another via two external connections, regardless of the total number of spu j turns. j

With a coil according to the innovation, not only absolute measurements can be made but it is also possible to carry out differential measurements. In this case, points the probe has two coils, their properties at each instant measured and compared with each other.

An example of a differential coil is illustrated in FIG. 7 and 8 explained. For the sake of clarity, each sub-coil is only one turn in FIG. 7 shown, while in Fig. 8 two turns

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are shown. The coil is composed of two identical groups 25, 25A, 27, 27A and 25 ', 25 ¹ A, 27', 27 ¹ A, which are arranged next to one another on common bobbin elements, such that a coil 27, 27A and 25 ' , 25 A ¹ are connected to each other by each of the groups. As a result of their opposite winding direction, their respective magnetic effects cancel each other out. In this way, the outer coils 25, 25A and 27 ', 27 ¹ A form the active coils of the probe. In the case of a coil that can be divided into two parts, the two parts that can be separated from one another are merely connected via two external connections 41, 41 ', regardless of the number of turns.

If it is a probe with separate functions, the coil is formed by two nested ones Groups of the type described above, with the connection takes place between the two separable parts via four external connection points, regardless of the number of the turns.

The connecting line 42 between the two segments 25A and 27'A can be equipped with a centrally arranged electrical Connection point 43 may be provided, via which both feeding and measurement are carried out.

As already indicated above, the coil windings can have a profile that deviates from a circular shape. Here, a profile can be selected which is adapted to the geometry of the test object. It is still does not require the axes of the different Coils that make up the probe on the

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6980/02 / Ch / Fr - 14-20, October 1975

are arranged on the same axis. Is the test object long and not straight, for example around a curved rod, the coil-carrying Spulenkör can per elements a correspondingly curved

j. Have a shape so that the levels of the various parts

bobbins do not run parallel to each other, like the

ε case is in the embodiments shown in the figures

\ - examples.

ί. In the case of the coil according to the invention, the individual coils

. be bare or bundled or encapsulated. In the latter

In the case shown in Fig. 9, the active parts 44 and 45 of the coil are each of a magnetic circuit 46 and 47 high permeability and suitable shape

; ben.

If the specimens have unfavorable shapes or dimensions, it may be necessary to split the coil in more than two Parts to share. In this case, of course, the number of external connection terminals increases, but is '* also in this case the number of connection ports

very small and independent of the number of coil turns due to the longitudinal conductors, their magnetic Influences cancel each other out.

In order to be able to carry out measurements quickly, you can go to a SpuJe divisible into two parts, these form a pair of pliers, which makes the handling easier compared to a coil consisting of two separate parts is made much easier.

- 15 claims

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Claims (1)

I 1 I I * G 75 33 531.8 April 15, 1976 CENTER TECHNIQUE 698o / o2 Expectations 1. Divisible coil arrangement for generating a magnetic field in an elongated specimen, where the magnetic field is equivalent to one of two separate, field generated by current flowing through coils in the opposite direction and wherein the coil arrangement consists of at least two separate parts that can be arranged around the test object, without guiding the coil arrangement over one end of the test object, characterized in that, that each part of the coil arrangement has two coil parts (21, 22) with a plurality of turns (25, 26, 25A, 26A; 27, 28, 27A, 28A), each of which is assigned to a coil and which are connected to one another via two conductor bundles (31, 33, 32; 31A, 33A, 32A) are connected that those associated with one coil Coil parts (25, 26, 25A, 26A) of the parts of the divisible coil arrangement in a first plane and the the other coil associated coil parts (27, 28; 27A, 28A) are arranged in a second plane, that in each case one conductor bundle (31, 33, 32) of a part of the divisible coil arrangement next to the other Conductor bundles (31A, 33A, 32A) of the adjacent part and both conductor bundles the same number of conductors have that the turns of two parts of the divisible coil assembly via a Terminal (H, J; M, N) are connected to one another and that, starting from each input terminal (A), the conductor wires each part of the divisible coil arrangement has the same sense of winding. 7533531 05.88.76 2. Coil arrangement according to claim 1, characterized in that a further coil arrangement of the same type in addition to the first coil arrangement arranged 1st. 3. Coil arrangement according to claim 1, characterized in that from the coil parts composite coils (44, 45) are bundled. 4. Coil arrangement according to claim 1 or 3, characterized characterized in that the coils (44, 45) assembled from the coil parts are each encapsulated by an inwardly open bundling device (46, 47). 5. Coil arrangement according to claim 1, characterized in that it has a longitudinal direction has split bobbins (1) made up of several bobbin parts (3, 4), each bobbin part (3, 4) has winding segments (25 to 28; 25A to 28A) made of coil wire, which extend from one parting plane to the other parting plane transversely to the longitudinal axis, the Segments on each bobbin part (3, 4) at least in a pair of groups of the same number of Segments is divided, which after assembly of the coil body parts (3, 4) at least one coil body pair form, the ends (A, B, E, F) of the segments (25, 26) of a group continuously and in always same direction of winding with the ends (D, C, G, H) of the Segments (27, 28) of the other group of the pair are connected (31, 33, 32) along a parting plane (2), at which ends the segments, after each group a single end (H, J; M, N) of the segments 7533531 08/05/76 t I * ι t * a »a Outwardly guided, at least two segment ends (A, S) designed as free input and output connections are and between the single, outwardly leading end (H, M) of the segments and one Corresponding end (J; N) of the segments of the adjacent bobbin part a releasable connecting device is arranged. 6. Coil arrangement according to claim 5, characterized in that the coil body (1) after the assembly of the bobbin parts (3, 4) has a circular cross-section. 7. coil arrangement according to claim 5, characterized in that the coil body (1) after assembly of the coil body parts (3, 4) a cross-section deviating from the circular cross-section Has cross section. 8. Coil arrangement according to one of claims 5 to 7, characterized in that the Coil body (1) after assembly of the coil body parts (3, 4) a straight line Having axis. 9. Coil arrangement according to one of claims 5 to 7, characterized in that the The coil body (1) has a curved axis after the coil body parts (3, 4) have been assembled. 1o. Coil arrangement according to one of Claims 5 to 7, characterized in that the coil body (1) is divided into two parts (3, 4), the plane of separation (2) of both parts passing through the coil body axis. 7533531 08/05/76 11. Coil arrangement according to claim 1 o, characterized in that the two coil body parts (3, 4) from the arms of a pincer-shaped Device are worn. 12. Coil arrangement according to claim 1 or 11, characterized characterized in that each of the two coil body parts (3, 4) is a pair of the segment groups carries, which after assembly of the parts result in an arrangement equivalent to two coils. 13. Coil arrangement according to claim 1 or 11, characterized characterized in that each of the two coil body parts (3, 4) has two pairs of segment groups carries, which after the assembly of the parts result in an arrangement equivalent to two pairs of coils, 14. Coil arrangement according to claim 13, characterized in that a group of one Segment pair is arranged next to a group of another segment pair and the winding sense of one group is opposite to that of the other group. 7533531 08/05/76