Scanner

An ultrasonic scanner has an encoder contacting a drum containing an array. The scanning assembly can be replaced via a snap fit formation. The encoder and drum are resiliently biased and movable relative to the chassis. The array can also be movable relative to the chassis.

RELATED APPLICATIONS

The present application is a national phase of PCT/GB2009/050338, filed Apr. 7, 2009, and Great Britain Application Number 0806997.3, filed Apr. 17, 2008.

FIELD OF THE INVENTION

The present invention is concerned with a scanner. More specifically, the present invention is concerned with an ultrasonic testing (UT) scanner for non-destructive testing of metal and composite structures etc.

BACKGROUND OF THE INVENTION

Non-visible areas of materials, such as the interiors of components, welds and composite materials can be analysed using ultrasonic testing. This type of non-destructive testing (NDT) utilises the reflection of sound waves to detect faults and features which would otherwise be very difficult to detect without destroying the component in the process. Ultrasonic testing is a common technique in the aerospace sector to test the integrity of materials at manufacture and during service.

Scanners tend to be of the portable type (i.e. more suited to in-service scanning) or non-portable type (specifically for production).

A feature of ultrasonic testing is that a couplant is required to aid transmission of the ultrasonic energy to the test specimen because the acoustic impedance mismatch between air and solids (i.e. such as the test specimen) is large. This causes reflection of the sound waves and a loss in scan quality if a couplant is not used. Couplants generally take the form of water or gel or a deformable solid.

Traditionally, ultrasonic testing has been limited in terms of inspection speed as the operation had to be carried out on a point-by-point basis. Improvements have led to the development of array scanning, or “paintbrush” scanning which permits a continuous scan over a surface to produce a two dimensional image of the desired region of the test component. Such equipment however is bulky and limited to use in a production (as opposed to service) environment and is not considered portable.

The issue of portability has been addressed with the development of the RapidScan system marketed by NDT Solutions Ltd. This system utilises a chassis to which a water filled rubber drum is rotatably mounted. An ultrasonic array is mounted to the axle and the water contained within the deformable rubber drum acts as the couplant.

The RapidScan system also features a rotary encoder mounted to the chassis proximate the drum. The chassis comprises a handle extending in the direction of travel of the RapidScan system.

In use, the chassis is held by the handle, proximate a workpiece with the drum and encoder contacting said workpiece, and moved such that the drum and encoder rotate. As this occurs, scanning takes place via the array. The scanned signal is fed from the array to a nearby computer for analysis. Simultaneously, the encoder transmits a signal to the computer such that the scanning position and hence the location of any features found can be determined.

There are various problems exhibited by this system. Firstly, the requirement for simultaneous contact of the drum and encoder means that the system cannot easily traverse significant changes in gradient of the workpiece. The device may become “grounded” (i.e. a part of the chassis between the encoder and drum may contact the workpiece). Alternatively, the drum or encoder may part contact with the surface leading to loss of useful results or loss of data relating to the distance travelled.

Also, the orientation of the chassis, and hence handle is fixed relative to the surface of the workpiece and hence the position of the user's hand is constrained in this respect. As such, in workpieces with particularly uneven surfaces, the user has to change the position of their hand relative to their arm/body several times. The various positions may also be uncomfortable to the user.

Also, it is often desirable to use a different frequency ultrasound array. Therefore it is necessary to carry several systems, each with different arrays to provide this functionality.

Further, the drum is mounted directly to the chassis. This limits the speed at which the array can traverse the workpiece as the user has to be careful not to allow the array to leave the workpiece surface at, for example, sharp changes in gradient of the surface or imperfections which the drum may “jump” over. If the drum leaves the workpiece the effect of the couplant is lost and the effectiveness of the scanner is significantly reduced.

Additionally, the stiff mounting arrangement between the drum and the chassis means that all of the force transmitted between the workpiece and the drum is transmitted to the user's hand, which may be uncomfortable in the case of shock or repetitive loading.

It is an aim of the present invention to overcome or at least mitigate at least one of the above problems.

SUMMARY OF THE INVENTION

According to a first aspect of the above invention there is provided a portable scanner comprising: a chassis, a scanning assembly having an ultrasonic scanning array and a rotating component rotatably mounted relative to the chassis, the rotating component comprising an ultrasonic couplant and having a peripheral contact surface for contacting a surface of a workpiece to provide ultrasonic coupling between the array and a surface of a workpiece such that movement of the chassis relative to a workpiece with the contact surface in contact with a surface of a workpiece results in rotation of the rotating component, and an encoder comprising a movement sensor, wherein the sensor is arranged to sense a movement of the rotating component.

In this way, the sensor does not need to have any kind of relationship with the surface of the workpiece which could impair its movement around certain features.

According to a second aspect of the above invention there is provided a portable scanner comprising: a chassis and a scanning assembly having an ultrasonic scanning array anda rotating component rotatably mounted relative to the chassis, the rotating component comprising an ultrasonic couplant and having a peripheral contact surface for contacting a surface of a workpiece to provide ultrasonic coupling between the array and a surface of a workpiece such that movement of the chassis relative to a workpiece with the contact surface in contact with a surface of a workpiece results in rotation of the rotating component, and wherein the rotating component is resiliently, translationally moveable relative to the chassis.

As such a form of suspension is provided in which the position of the rotating component is able to adjust to follow variations in the surface without the user needing constantly to adjust the position of their hand holding the scanner.

According to a third aspect of the above invention there is provided a portable scanner comprising: a chassis and a scanning assembly having an ultrasonic scanning array anda rotating component rotatably mounted relative to the chassis, the rotating component comprising an ultrasonic couplant and having a peripheral contact surface for contacting a surface of a workpiece to provide ultrasonic coupling between the array and a surface of a workpiece such that movement of the chassis relative to a workpiece with the contact surface in contact with a surface of a workpiece results in rotation of the rotating component, and wherein; the scanning assembly is removably mounted to the chassis via a quick release formation.

As such, only one scanner chassis is required and scanning assemblies can be easily replaced depending on the requirements of the task.

According to a fourth aspect of the above invention there is provided portable scanner comprising: a chassis and a scanning assembly having an ultrasonic scanning array anda rotating component rotatably mounted relative to the chassis, the rotating component comprising an ultrasonic couplant and having a peripheral contact surface for contacting a surface of a workpiece to provide ultrasonic coupling between the array and a surface of a workpiece such that movement of the chassis relative to a workpiece with the contact surface in contact with a surface of a workpiece results in rotation of the rotating component, and wherein the array is rotatable relative to the chassis.

As such the handle can be moved relative to the array to suit the user's preference for comfort or to use the array in environments where space is limited.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Referring toFIGS. 1ato1ca prior art scanner10is shown schematically and comprises a chassis12, an encoder wheel14and a drum16. The encoder wheel14and the drum16both contact a surface of a workpiece8. The encoder10further comprises an array (not shown) located fixed to the chassis12and substantially coincident with the axis of rotation of the drum. The array has a scanning direction18in which it emits and receives ultrasonic waves to and from the workpiece8. The scanning direction18is fixed relative to the chassis12. The chassis has a handle20by which it may be moved across the workpiece8with the encoder wheel14and drum16rotating relative to the chassis.

In order for the scanner10to satisfactorily scan the workpiece8, the scanning direction18should be perpendicular to the surface of the workpiece8. This occurs inFIG. 1ain which the workpiece8has a flat surface.

InFIG. 1b, the scanner has encountered a convex surface of the workpiece8. In traversing the workpiece8the scanner chassis12has fouled on it. As such one of the encoder wheel14and drum16cannot contact the workpiece8leading to poor performance. In particular, the scanning direction18is not perpendicular to the workpiece8.

InFIG. 1cthe scanner has encountered a concave surface of the workpiece8. Although both the encoder wheel14and the drum16are contacting the workpiece, the scanning direction18is not perpendicular to it as the encoder wheel14restricts rotational movement of the scanner10. This results in poor performance.

Referring now toFIG. 2a, a scanner100in accordance with the present invention is shown. The scanner100comprises a chassis102, an encoder assembly104and a scanning assembly106.

The chassis102comprises an elongate cylindrical handle110for a user to grip in his/her hand. The chassis102further comprises a frame112extending from the handle110which splits into two arms114,116to form a “Y” shape. The arms114,116of the “Y” comprise parallel sections118,120respectively. The parallel sections118,120terminate with inwardly depending sections124(only one is shown).

The inwardly depending sections124in turn terminate in clip plates128(only one is shown inFIG. 3).

A pair of parallel, facing grooves130(only one shown) are formed in the parallel sections118,120whose function will be discussed below.

The encoder assembly104comprises a shaft132on which an encoder134is rotatably mounted. The encoder134is of the rotary type and is configured to determine the distance travelled over the surface in which it is in contact.

The scanning assembly106comprises an axle136onto which an ultrasonic scanning array138is mounted. At either end of the axle136there are positioned clip receiving assemblies140(only one shown inFIG. 3) which comprise (with reference toFIG. 3) a base plate142, a channel section rim144and resiliently mounted retaining pins146.

The scanning assembly further comprises a drum148having a rubber body containing water to act as a couplant for the array138. The drum148is rotatably mounted to the axle136such that it can rotate relative to the array138.

The encoder assembly104is mounted to the chassis102by inserting the ends of the shaft132into the grooves130. Springs150(only one shown inFIG. 2B) are also inserted into the grooves130to bias the shaft132away from the handle110of the chassis102.

The scanning assembly106can then be assembled to the chassis102by inserting the clip plates128into the clip receiving assemblies140. As this is performed, the retaining pins146are urged outwards to allow the clip plates128to pass. Once the clip plates128are securely within the clip receiving assemblies the retaining pins resile to their original positions to retain the scanning assembly in position.

Whilst the scanning assembly is being assembled to the chassis102as described above, the drum148contacts the encoder134and moves it against the bias of the springs150. When in position, the drum148is therefore reliably contacted by the encoder134.

Both the array138and the encoder134are connected to a computer152for collecting information regarding the scanning results (via the array138) and the position of the scanner (via the encoder134). The encoder and scanner have signal feed wires (not shown) which connect to a main cable154which leads from the handle110to the computer152.

Referring toFIG. 4athe scanner100is shown traversing a workpiece80similar to that shown inFIG. 1b. The scanner100is held by a user (not shown) with the handle110perpendicular to the surface of the workpiece80. The array138scans the workpiece80by sending and receiving ultrasonic waves in a scanning direction156. When moving over the corner of the workpiece, the handle110can be manoeuvred by the user to remain perpendicular to the surface, thus maintaining a perpendicular scanning direction156as shown.

As can be observed, the ability to keep the scanning direction156perpendicular to the surface is enabled by the single contact point (or line) between the drum148and the workpiece80. As the encoder134determines the distance travelled by the drum148there is no need for it to contact the workpiece80and as such the problems observed inFIGS. 1band1cdo not occur.

Scanner100inFIG. 4ashows the array138arranged with its scanning direction156parallel to the handle110. It is envisaged that the array may be arranged at an angle to the handle110. An example of this is shown inFIG. 4bwhere an scanner200has features numbered as scanner100, but 100 greater.

The scanner200is similar to the scanner100except that the clip plates228are mounted at an angle to the chassis202and hence handle210. Therefore in order to maintain the scanning direction256parallel to the workpiece80the handle210needs to be positioned at an angle A relative thereto. An arrow or sign may be provided on the clip plate outer to inform the user of the required scanning direction256.

This arrangement may be more comfortable for the user than when the handle is perpendicular to the surface (i.e. when A=90 degrees).

The clip plates228may be adjustably mounted to the chassis202to provide user adjustment capability which may be varied depending on the user's comfort levels and space available for scanning.

Alternatively, the clip receiving assemblies may be oriented as per scanner100, and the array may be angled with respect to the clip receiving assemblies140. As such the angle A would be dependent on the choice of scanning assembly106.

Referring toFIG. 5, a scanner300is shown which is similar to the scanner100. Common features are numbered 200 greater. In place of parallel sections118,120, the arms314,316of the frame312of the chassis302comprise longitudinal bores360,362respectively. A pair of pistons364,366are located in the respective bores360,362and are biased to an extended position via springs368,370.

The pistons364,366can move axially with respect to the frame312.

Each of the pistons364,366has a clip plate (not shown) mounted thereto which is engaged with the clip retaining formations340of the scanning assembly306as described above.

The encoder assembly304is also resiliently mounted to be biased towards the scanning assembly306as per scanner100. However, due to the location of the above piston arrangement the encoder assembly is resiliently mounted with the shaft332movable in slots330in additional lugs372and biased with spring350(seeFIG. 6).

In use, the scanning assembly306of the scanner300is therefore resiliently movably mounted to the chassis302. During use, movement of the drum348is accompanied by movement of the encoder assembly304such that the drum348and encoder334are always in contact.

Referring toFIGS. 7a-7c, the scanner300is propelled along a surface of a workpiece80in a direction D by the user. The surface contains an imperfection or concave feature82which the scanner300has to traverse. The user is applying a light pressure in the scanning direction356. The springs368,370are schematically represented as lightly compressed.

When the scanner encounters the feature82the springs368,370are able to extend to allow the drum348to remain in contact with the workpiece80. As such, contact is not lost and the scan may be completed successfully.

Turning toFIGS. 8aand8ba scanner400is shown substantially similar to the hand scanner300with common features numbered 100 greater.

In the case of scanner400, the axle436is mounted to the arms414,416of the frame412of the chassis402via tilt bearings474such that the axle436may rotate relative to the frame412. The array438is mounted to the axle to scan in the scanning direction456.

The drum448of the scanning assembly406is rotationally mounted relative to the axle436as in previous embodiments. The drum448is shown in section with water filled bladder476acting as the couplant.

Two stabilisers478are attached to the axle436where it protrudes from the drum448and extend radially therefrom. The stabilisers extend approximately to the outer perimeter of the drum448.

In use, the outer periphery of the drum448contacts the workpiece80and can roll on it as previously described. In scanner400however, the stabilisers478prevent rotation of the axle436with respect to the surface of the workpiece80as they run over it. As such, the array438is orientated such that the scanning direction456is always perpendicular to the surface of the workpiece80.

Additionally, the frame412may be rotated with respect to the scanning assembly406without moving the position of the array438by virtue of the tilt bearings474. Accordingly, the user can continuously adjust his/her hand position if desired to achieve a greater comfort level or use the scanner400in confined spaces.

Turning toFIGS. 9ato9c, the scanner400is shown in a variety of positions with the drum448and the stabilisers478contacting the workpiece80. As shown inFIGS. 9band9c, the angle of the surface and/or the angle of the handle of the device can be altered without affecting the scanning direction's perpendicularity to the surface of the workpiece80.

Many variations of the embodiments described fall within the scope of the present invention.

For example, the use of the encoder contacting the drum, the resiliently mounted drum, the snap fit and the stabilisers may be used alone or in any suitable combination depending on the application.

The improvements described above may be applied to a non-portable (production type) scanner as well as a portable (in-service) scanner as discussed.

The snap fit connection may be any quick release formation such as recessed sprung pins, quarter turn bolts/screws, butterfly nuts and the like.

The encoder may be of any type, for example a mechanical device as discussed above, or an optical device which reads the surface of the drum without contact.

The drum may take any form and need not be water filled to achieve coupling, for example deformable solids or gels may be appropriate.

The array and encoder may not be connected to the computer via a wired connection, but may be wireless.

The connection between the array and the computer may be achieved via a contact connection within the mounting point of the scanning assembly and the frame—for example the frame may have exposed connections on the clip plate and the scanning assembly may have corresponding connections on the clip receiving assemblies.

The device may only comprise a single stabiliser.

Various figures depict an encoder234, an array238, a clip receiving assembly240, a drum248and an encoder434. As detailed above, encoder200has features numbered as encoder100, but 100 greater, scanner300is shown which is similar to the scanner100, where common features are numbered 200 greater, and scanner400is shown substantially similar to the hand scanner300with common features numbered 100 greater.