A TEST PROBE

The invention relates to an ultrasonic test probe for the non-destructive inspection of workpieces. In particular, the invention relates to an ultrasonic test probe with a novel electrical contact connection of an included ultrasonic transducer and method for producing a test probe according to the invention.

An ultrasonic test probe substantially consists of an ultrasonic transducer and a housing in which the transducer is disposed. The ultrasonic signal is output via the ultrasonic transducer. This ultrasonic transducer usually comprises a piezo-electric element formed in a flat manner. Electrodes are formed on the cover surfaces of the piezo-electric element, which can, in particular, be configured as an electrically conductive coating, and which substantially cover the entire cover surfaces. The electrodes are often configured as a metallic coating of the cover surfaces. In this case, one of the electrodes is connected to a ground contact and the other electrode is electrically contacted in such a way that an incoming electrical signal can be transmitted to the piezo element. The piezo element is made to oscillate by the incoming electrical signal, which leads to the emission of ultrasonic waves into the substance to be inspected. A couplant is also used for the non-destructive testing of workpieces, but also in medicine, in order to ensure an optimum coupling of the ultrasound to the surface. This can be, for example, water, oil or a gel. The reflected ultrasonic signal is received and converted into an electrical signal, which is forwarded to a corresponding evaluation unit for further processing.

For the angle-dependent testing of a workpiece, the ultrasonic transducer is acoustically coupled to a leading body. In turn, the latter is acoustically coupled to the workpiece to be inspected, generally using a suitable couplant. For example, the leading body is wedge-shaped and formed from Plexiglas®. For example, it is a cast or cut part of Plexiglas® which is milled so as to be plane on the coupling surface and the underside.

There are still process steps in the manufacture of ultrasonic test probes that have to be carried out manually. In particular, in today's prior art, complex steps, which can in part only be carried out manually, are required to electrically contact the flat electrodes formed on the ultrasonic transducer.

DE 699 12 132 describes an ultrasonic transducer arrangement and a method for producing an ultrasonic transducer arrangement in which the the piezo-electric element is contacted through a cut-out between a supply line and a matching layer. It is apparent from the description that the realization of such a cut-out can only be realized by means of complex etching steps followed by insulation methods.

Document US 6895825 discloses an ultrasonic transducer and a method for producing an ultrasonic test probe, wherein an electrically conductive contact surface of the ultrasonic transducer is soldered directly to the housing and is thus connected to a ground contact via the electrically conductive surface on the inner housing wall. A second electrically conductive contact surface of the ultrasonic transducer is connected via a wire routed towards the outside through an opening in the housing. The difficulty in this embodiment lies in ensuring that the wire is electrically insulated from other electrically conductive surfaces located in the housing. Furthermore, there is the danger of damage to the wire when removing a provided housing cover.

It is the object of the present invention to specify an ultrasonic test probe having advantageous assembly properties, as well as an advantageous method for producing such an ultrasonic test probe. Advantageous within the context of the present invention means, in particular, that the test probe is capable of being mounted in a largely automated manner

This object is achieved by an ultrasonic test probe according to claim 1 as well as by a method for producing a test probe according to claim 14. Further advantageous embodiments of the test probe or advantageous further embodiments of the method are specified in the dependent claims. It is pointed out that the applicant reserves the right to strive to obtain separate protection for a test probe with the features of claim 12 that is independent from the features of the characterizing portion of claim 1. The present invention relates to an ultrasonic test probe comprising at least one ultrasonic transducer with at least one electrically conductive contact surface. The ultrasonic transducer is disposed on a leading body, which may consist, for example, of Plexiglas®. Both the leading body as well as the ultrasonic transducer are disposed in a common housing. Preferably, the ultrasonic transducer is configured to be flat, with at least one of the cover surfaces of the ultrasonic transducer being coated with an electrically conductive layer, whereby a first electrically conductive contact surface is formed. For example, this is a piezoceramic configured to be flat, with a cover surface for forming an electrode being coated, for example, with a film of aluminum, silver, gold or platinum.

Furthermore, the ultrasonic test probe comprises, according to the invention, a first electrical contact element which is also disposed in the housing of the ultrasonic test probe. The first contact element forms a first resilient contact arm. According to the invention, the first resilient contact arm of the first electrical contact element now contacts the first electrically conductive contact surface of the ultrasonic transducer due to spring force, i.e. the first contact arm is resiliently pressed against the first contact surface, whereby the first contact arm contacts the first contact surface electrically. In this case, the first electrical contact element can be, for example, a stamped part consisting of spring plate. According to a first preferred embodiment, the ultrasonic transducer is disposed on the leading body in such a way that the first electrically conductive contact surface of the ultrasonic transducer faces towards the leading body.

In the first preferred embodiment, the first electrical contact element is also preferably disposed on the leading body. According to a preferred development, the leading body moreover comprises a contact bed for the first contact element, the shape of the contact bed being adapted to the first electrical contact element. Preferably, the shape of the contact bed is adapted to the contour of the first contact element, so that the first contact element is positively received by the contact bed. Particularly preferably, the first electrical contact element inserted into the contact bed is mechanically retained there in a force fit. A force fit within the sense of the invention is to be understood to mean that something is being fixed in a position due to mechanical forces.

Moreover, the leading body preferably comprises a pre-structured portion in the form of a cut-out, which is formed to accommodate therein the first resilient contact arm of the first electrical contact element in a resilient manner. According to another embodiment, the ultrasonic transducer is attached to the leading body in such a way that the first electrically conductive contact surface faces towards the ultrasonic transducer and covers the pre-structured cut-out at least partially. The first resilient contact arm is biased against the first contact surface. The first resilient contact arm of the first electrical contact element is thus pressed into the cut-out, and a reliable electrical contact connection of the first electrically conductive contact surface of the ultrasonic transducer results from the spring force acting in the opposite direction.

In another advantageous development, the first electrical contact element comprises two second resilient electrically conductive contact arms, which contact due to spring force a ground contact formed at the inner face of the housing. In this way, the first electrically conductive contact surface of the ultrasonic transducer is securely connected to the ground contact in an electrically conductive manner. In this case, the ground contact can advantageously be formed by a housing that is electrically conductive as a whole, or by an electrically conductive coating on the inner housing wall.

In a second preferred embodiment of the ultrasonic test probe according to the invention, the ultrasonic transducer is disposed on the leading body in such a way that the electrically conductive contact surface of the ultrasonic transducer faces away from the leading body. Furthermore, it has proved advantageous if an acoustic damping element is disposed on the cover surface of the ultrasonic transducer facing away from the leading body, because interfering ultrasonic echoes emanating from the cover surface of the ultrasonic transducer facing away from the leading body can be minimized in this manner. In this case, a particularly simple electrical contact connection of the electrically conductive contact surface of the ultrasonic transducer facing away from the leading body is possible if it is formed on a cover surface of the damping element facing away from the ultrasonic transducer.

According to another embodiment, a circuit board is disposed on the cover surface of the ultrasonic transducer facing away from the leading body. The electrically conductive contact surface of the ultrasonic transducer facing away from the leading body is electrically contacted via a bottom contact surface of the circuit board, which is connected to a top contact surface of the circuit board via a through-hole contact. An inductor is connected between the bottom and the top contact surfaces of the circuit board. For example, the circuit board can be a PBC circuit board or a circuit board of a material that, at the same time, can act as a acoustic damping element. For example, the through-hole contact is a VIA through- hole contact. According to this exemplary embodiment, the top contact surface of the circuit board can be contacted, in analogy to the contact surface of the ultrasonic transducer, with a first electrical contact element having a spring arm, with the contact surface of the ultrasonic transducer facing away from the leading body being contacted at the same time.

Regardless of whether the contact surface in the second preferred embodiment is formed on the cover surface of the ultrasonic transducer facing away from the leading body or on the cover surface of the damping element facing away from the ultrasonic transducer, certain advantages with regard to their electrical contact connection can be realized if the first electrical contact element is mechanically connected to the housing in such a way that it extends from the inner face of the housing into its interior. In this case, this first electrical contact element is preferably disposed in such a way that it automatically comes into mechanical contact with the contact surface and contacts it electrically during the assembly of the test probe according to the invention, i.e. during the joining of the leading body and the ultrasonic transducer disposed thereon with the housing. For this purpose, the contact element can be configured, for example, as a coil spring of an electrically conductive material, e.g. a metal, or also as a stamped part of an electrically conductive, e.g. metallic, spring plate.

Particularly preferably, an electrical terminal member provided for the external connection of a control line for the ultrasonic transducer is provided on the housing of the test probe. This can be, in particular, a high-voltage proof standardized socket of a plug-in connector, e.g. a BNC socket. A particularly simple configuration of the ultrasonic test probe according to the invention is obtained if the first electrical contact element is connected in an electrically conductive manner to a terminal lug of the terminal member located in the housing interior.

If an acoustic damping element is disposed at the rear of the ultrasonic transducer, certain advantages are obtained if the ultrasonic test probe according to the invention further comprises a second electrical contact element different from the first contact element. This second electrical contact element forms a contacting foot that electrically contacts that cover surface of the ultrasonic transducer that faces away from the leading body and is disposed between the ultrasonic transducer and the damping element. Furthermore, the second contact element forms an electrically conductive contact surface disposed on the cover surface of the damping element facing away from the leading body. The second contact element is configured in such a way that it electrically interconnects the contacting foot and the electrically conductive contact surface.

In practice, it has proved to be particularly advantageous if the first and/or the second electrical contact elements are formed as a stamped part of spring plate, optionally also as a folded stamped part. By means of a suitable surface treatment, such a chromium plating, the corrosion properties of the spring plate can be improved even more.

The design of the test probe according to the invention enables a particularly rational manufacture thereof, because it is largely automated. Due to the significantly simplified contact connection of the ultrasonic transducer, which no longer requires any cords or strip line connections, a largely complete assembly of the ultrasonic test probe can take place, in particular, using assembly robots. An advantageous method for producing a ultrasonic test probe according to the invention comprises at least the following method steps: a. disposing a first electrical contact element on the leading body or/and on the housing, and b. disposing the ultrasonic transducer on the leading body, and c. joining the housing and the leading body with the ultrasonic transducer disposed thereon, in such a way that the first resilient contact arm electrically contacts the contact surface due to spring force. In an advantageous development of the method according to the invention, the first electrical contact element moreover forms a second resilient contact arm. Furthermore, the housing forms a ground contact disposed on the inner face of the housing. When the leading body with the first electrical contact element disposed thereon and the ultrasonic transducer is inserted into the housing, the second resilient contact arm contacts the ground contact in an electrically conductive manner due to spring force. If the second resilient contact arm and the ground contact are suitably arranged, this happens completely automatically without any intervention by assembly personnel being required.

A particularly low error rate in the assembly of an ultrasonic test probe according to the invention can be obtained if the following further method steps are carried out additionally: a. forming a contact bed, which is adapted to the shape of the first electrical contact element, in the leading body, and b. inserting the first electrical contact element into the pre-structured contact bed. The resulting positive fit between the contact element and the contact bed results in a secure seat of the contact element on the leading body during the assembly of the test probe, which can be enhanced even more if the contact element is glued on and if a force fit of the contact element on the leading body or in the contact bed is additionally realized.

Other advantages and features of the invention become apparent from the dependent claims as well as from the exemplary embodiments, which are to be understood not to be limiting and which will be explained below with reference to the drawing. In the drawing:

Fig. 1 : shows a perspective view of the leading body of an ultrasonic test probe according to the invention according to a first exemplary embodiment,

Fig. 2: shows a perspective view of the leading body from Fig. 1 with the first electrical contact element disposed thereon,

Fig. 3 : shows a perspective view of the ultrasonic transducer according to the first exemplary embodiment,

Fig. 4: shows a perspective view of the leading body from Fig. 1 with the first electrical contact element disposed thereon and the ultrasonic transducer,

Fig. 5: shows a bottom view of the housing of the ultrasonic test probe according to the first exemplary embodiment,

Fig. 6: shows a schematic sectional view of the ultrasonic test probe according to the first exemplary embodiment,

Fig. 6a: shows a schematic view of a circuit board for extending the ultrasonic test probe according to the first exemplary embodiment,

Fig. 7: shows an exploded view of a second exemplary embodiment of the ultrasonic test probe according to the invention, and

Fig. 8: shows an exploded view of an ultrasonic transducer, a second electrical contact element and a damping element according to the second exemplary embodiment of an ultrasonic test probe according to the invention. Fig. 1 shows a wedge-shaped leading body 20 according to a first exemplary embodiment. The leading body 20 is a single-piece cast part of Plexiglas®, whose underside, which comprises a base 4, and the coupling surface are milled to be plane. Moreover, the leading body 20 comprises a contact bed 22 whose shape is adapted to a first electrical contact element (30) (not shown here). Furthermore, the leading body 20 comprises a pre-structured portion in the form of a cut-out 24. Other features of the leading body 20 that simplify the assembly of an ultrasonic test probe 1 according to the invention are a base 4, onto which a housing 2 (not shown) can be plugged and retained, and an abutting edge 6, which facilitates the positioning of an ultrasonic transducer 10, which is not shown here yet.

Fig. 2 shows the leading body 20, on which a first electrical contact element 30 consisting of spring plate with a first resilient contact arm 32 and two second resilient contact arms 34, 34', in this case in a T-shaped design, is positively disposed in the contact bed 22, for example by means of glueing, pressing, clamping. Moreover, the second resilient contact arms 34, 34' comprise contact tips 35. The shape of the contact bed 22 already shown in Fig. 1 and of the first electrical contact element 30 are adapted to each other so as to be an exact fit, so that the first electrical contact element 30 is retained in the contact bed 22 of the leading body 20, for example in a force fit. The first resilient contact arm 32 is configured to take two positions. Fig. 2 shows the first resilient contact arm 32 in a first position, which it typically takes prior to the attachment of the ultrasonic transducer. The design of the pre-structured cut-out 24 of the leading body 20 is suitable to resiliently accommodate therein the first resilient contact arm 32 of the first electrical contact element 30.

Fig. 3 shows a perspective view of the ultrasonic transducer 10 according to the first exemplary embodiment. The ultrasonic transducer 10 consists of a piezoceramic configured in a flat manner, whose opposing cover surfaces are coated with an electrically conductive material, such as gold. These surfaces form a first electrically conductive contact surface 12 and a second electrically conductive contact surface 14. The layer thickness relations are not to be considered to be to scale. The drawing is only to serve to illustrate an ultrasonic transducer 10 configured in a flat manner with first and second electrically conductive contact surfaces 12 and 14 formed on the opposing cover surfaces of the ultrasonic transducer 10, as it is used in accordance with the first exemplary embodiment.

Fig. 4 shows a perspective view of the leading body 20 according to Fig. 1 and Fig. 2, with the first electrical contact element 30 disposed thereon and the ultrasonic transducer 10, whose structure corresponds to that shown in Fig. 3. The ultrasonic transducer 10, which comprises a first electrically conductive contact surface 12 and a second electrically conductive contact surface 14, is attached to the leading body 20 and fixed there in such a way that the first electrically conductive contact surface 12 faces towards the leading body 20 and partially covers the pre-structured cut-out 24 of the leading body 20. As is shown in Fig. 4, the first resilient contact arm 32 of the first electrical contact element 30 is in a second position and is biased against the first electrically conductive contact surface 12. Thus, the first electrically conductive contact surface 12 of the ultrasonic transducer 10 facing towards the leading body 20 is contacted due to spring force. In the first exemplary embodiment shown, the second resilient contact arms 34, 34' of the first electrical contact element 30 comprise contact tips 35 that are suitable to contact, due to spring force, a ground contact 50 formed on the inner face of the housing 2.

A bottom view of a corresponding housing 2 is shown in Fig. 5. In the exemplary embodiment shown here, the housing is formed from an electrically conductive material, for example from metal, so that the ground contact 50 extends over the entire inner housing wall.

After joining the housing 10 according to Fig. 4 and the leading body 2, the contact tips 35 of the second resilient contact arm 34, 34' of the first electrical contact element 30 touch the inner wall of the housing 2 and thus contact the first electrically conductive contact surface 12 of the ultrasonic transducer 10 with the ground contact 50.

Furthermore, Fig. 5 shows a third electrical contact element 52 with a third resilient contact arm 54 of spring steel, which is provided to contact, due to spring force, the upper second electrically conductive contact surface 14 of the ultrasonic transducer 10 facing away from the leading body 20. Via a terminal lug 62, such as a BNC socket, the third electrical contact element 52 is mechanically connected to the housing 2 in such a way that it extends from the inner face of the housing 2 into its interior. This third electrical contact element 52 is arranged in such a way that the third resilient contact arm 54 of the third electrical contact element 52 automatically comes into mechanical contact with the second electrically conductive contact surface 14 facing away from the leading body 20 and contacts the contact surface electrically when the housing 2 is joined with the leading body 20 and the first electrical contact element 30 disposed thereon and the ultrasonic transducer 10. In the exemplary embodiment shown here, the third resilient contact arm 54 is formed from spring plate.

Fig. 6 shows the inventive ultrasonic test probe 1 according to the first exemplary embodiment in a schematic sectional view. The first electrical contact element 30 with the first resilient contact arm 32 and the second resilient contact arm 34 is positively disposed in the contact bed 22 of the leading body 20. The first resilient contact arm 32 lies in the pre-structured cut-out 24. The ultrasonic transducer 10 is disposed flush with the abutting edge 6 of the leading body 20 and fixed by, for example, glueing, so that the first electrically conductive contact surface 12 of the ultrasonic transducer 10 faces towards the leading body 20 and partially covers the cut-out 24. The first resilient contact arm 32 of the first electrical contact element 30 contacts the first electrically conductive contact surface 12 of the ultrasonic transducer 10 due to spring force. The third electrical contact element 52 with the third resilient contact arm 54 is disposed on the inner face of the housing 2 of the ultrasonic test probe 1. The second electrically conductive contact surface 14 of the ultrasonic transducer 10 is contacted by the third resilient contact arm 54 of the third electrical contact element 52. The third resilient contact arm 54 is connected via a terminal lug 62 of a terminal member 60 located within the housing 2. This terminal member 60 is provided for the external connection of a control line for the ultrasonic transducer 10. For example, this is a BNC socket.

Fig. 6a schematically shows a circuit board 70 for optionally extending the inventive ultrasonic test probe according to a first exemplary embodiment. The circuit board 70 forms on the opposing cover surfaces a bottom and a top electrically conductive contact surface 76 and 78 which are interconnected in an electrically conductive manner through a VIA through-hole contact 72 or a connection acting in the same way. Furthermore, this connection comprises an inductor 74. The circuit board 70 is, for example, a PBC circuit board. The circuit board 70 is disposed on the ultrasonic transducer 10 in such a way that the bottom electrically conductive contact surface 76 faces towards the leading body 20 and is connected in an electrically conductive manner to the second electrically conductive contact surface 14 of the ultrasonic transducer 10. The top electrically conductive contact surface 78 is located on the side of the circuit board 70 facing away from the leading body 20 and is configured in such a way that it is contacted through the third resilient contact arm 54 of the third electrical contact element 52.

Fig. 7 shows an exploded view of a second exemplary embodiment of the ultrasonic test probe 1 according to the invention. In analogy to the first exemplary embodiment, the ultrasonic test probe 1 according to the invention comprises a wedge-shaped leading body 20 formed in a single piece, for example a cast part of Plexiglas®, which is milled so as to be plane on the coupling surface and the underside of a base 4. The shape of the contact bed 22 is adapted to a first electrical contact element 30, and an abutting edge 6 simplifies the mounting of a ultrasonic transducer 10 provided in this exemplary embodiment, which is configured in a flat manner. The base 4 of the leading body is provided to position and retain a housing 2. The first electrical contact element 30 is positively disposed in the contact bed 22, for example by glueing, pressing, clamping. Moreover, the leading body 20 comprises a pre-structured portion in the form of a cut-out 24, which is formed to accommodate therein the first resilient contact arm 32 of the first electrical contact element 30 in a resilient manner. The first electrical contact element 30 with a first resilient contact arm 32 and two second resilient contact arms 34, 34' is positively disposed in the contact bed 22 of the leading body 20. The biased first resilient contact arm 32 lies in the pre-structured cutout 24. The ultrasonic transducer 10 on disposed on the leading body 20 in such a way that a first electrically conductive contact surface 12 disposed on a cover surface of the ultrasonic transducer 10 facing towards the leading body 20 partially covers the cutout 24. Thus, the first resilient contact arm 32 of the first electrical contact element 30 is pressed into the cut-out 24 , and the first electrically conductive contact surface 12 of the ultrasonic transducer 10 is contacted due to spring force. Up to here, the structure corresponds to that of the first exemplary embodiment.

An acoustic damping element 16, which is configured so as to be flat, is disposed on the top cover surface of the ultrasonic transducer 10 facing away from the leading body 20, in order to minimize interfering ultrasonic echoes emanating from the cover surface of the ultrasonic transducer 10 facing away from the leading body 10. According to the second exemplary embodiment, the ultrasonic test probe 1 according to the invention comprises a second electrical contact element 40. This second electrical contact element 40 forms a contacting foot 44 disposed between the damping element 16 and the ultrasonic transducer 10. The second electrical contact element 40 contacts a second electrically conductive contact surface 14 formed on the cover surface of the ultrasonic transducer 10 facing away from the leading body 20. Furthermore, the second contact element 40 forms a contact surface 42 disposed on the top cover surface of the damping element 16 facing away from the leading body 20. The second contact element 40 is configured in such a way that it interconnects the contacting foot 44 and the contact surface 42 in an electrically conductive manner. The contact surface 42 is preferably electrically contacted by a third electrical contact element 52 as it is described in accordance with a first exemplary embodiment.

Fig. 8 shows the ultrasonic transducer 10, the second electrical contact element 40 and the damping element 16 according to the second exemplary embodiment. The ultrasonic transducer 10 is configured as shown in Fig. 3, i.e. the ultrasonic transducer 10, which is configured so as to be flat, comprises a first electrically conductive contact surface 12 and a second electrically conductive contact surface 14, which are formed on opposite cover surfaces of the ultrasonic transducer. The second electrical contact element 40, which consists, for example, of a folded stamped part, comprises a contacting foot 44 and a contact surface 42. The second electrical contact element is disposed on a cover surface of the ultrasonic transducer 10 in such a way that the contacting foot 44 is connected in an electrically conductive manner to the second electrically conductive contact surface 14 of the ultrasonic transducer 10. Furthermore, the contacting foot 44 of the second electrical contact element 40 comprises an opening 46, which is designed in such a way that a damping element 16 can be disposed, for example positively, within this opening 46. The contact surface 42 of the second electrical contact element 40 is disposed on the cover surface of the damping element facing away from the ultrasonic transducer 10.