MOUNTING ARRANGEMENT

Abstract: A mounting arrangement for an ultrasonic probe (10) for use in apparatus for non-destructive testing of materials, is mounted within an adaptor plug (12) having the form of a truncated cone. The peripheral surface of the plug (12) has five raised contact points comprising axially aligned points (14, 16) restraining translation along the Y axis and rotation about the X axis, axially aligned points (18, 20) restraining translation along the X axis and rotation about the Y axis, and point (22) restraining translation along the Z axis. The latter corresponds to the axis of the probe (10). The contact points provide for kinematic location of the plug (12) within a conical receiver, the latter being mounted on an ultrasonic testing machine and accurately aligned with the machine axis. The position of the probe (10) is initially adjusted relative to the plug (12) during a standard calibration procedure, and thereafter the probe (10) can be accurately and repeatedly mounted within the receiver.

Description: Mounting Arrangement This invention concerns a mounting arrangement for use in apparatus for the testing or working of materials, and relates particularly but not exclusively to an arrangement for the repeatable mounting of an ultrasonic probe in apparatus for non-destructive testing. Apparatus for non-destructive ultrasonic testing generally includes a probe for emitting ultrasonic waves directed to one side of the material to be tested and a probe for receiving the waves on the opposite side of the material. The waves are transmitted through a liquid or solid; commonly they are directed along respective jets of water on the opposed sides of the material, or are passed through a tank of water. The received wave signal is analysed by computer. In order to make a meaningful analysis, it is necessary to maintain the ultrasonic wave axes in alignment. Although the axes of the respective probe housings on the machine, i.e. the machine axes, can be maintained in alignment by computerised control, the ultrasonic axes are subject to angular and linear offsets relative to the machine axes. Calibration and adjustment is therefore necessary. This adjustment may be either a physical adjustment of the probe, or a software adjustment to a control system for the machine axes. In order to obviate the need for a separate calibration and adjustment procedure each time a probe is used, it is desirable that the probe should be repeatably mountable on the machine. However, for reasons of cost and manufacturing difficulty, conventional probe housings are not usually of accurate geometry or size, nor are they always sufficiently rigid to allow the probe housing itself to be used as a location feature. Various solutions have been proposed to the problem of providing an accurate probe mount. Calibration and adjustment may be carried out each time the probe is fitted, however this wastes machine time and is therefore expensive. Attempts have also been made to provide a repeatable (kinematic) mount for the probe, but in general these have not been sucessful due at least in part to probe body geometrical errors and hence uncertainty in the initial calibration process. According to the present invention there is provided a mounting arrangement for use in a material testing or working machine, the arrangement comprising signal emitting and/or receiving means, and means for mounting the signal means on a material testing or working machine, the mounting means comprising locating means for the signal means and means for receiving the locating means on the machine, one of the receiving means and the locating means being adapted to provide for a repeatable kinematic mounting of the locating means on the receiving means, the signal means being capable of initial calibration and adjustment relative to the locating means whereby there is provided a repeatable kinematic mounting for the signal means on the machine. Preferably the locating means and the receiving means respectively comprise a plug adaptor and a corresponding socket. Preferably the receiver has an axis of rotational symmetry, which may coincide with the required axis of propagation of the ultrasonic signal. The locating means preferably includes contact points which provide for kinematic location of the locat¬ ing means on the receiving means. The kinematic mounting may provide four, five or six degrees of restraint, but preferably there are five degrees of restraint, with rotation being permitted about the axis of the ultrasonic wave signal . In a first arrangement, the adaptor takes the form of a truncated cone with the probe mounted adjacent the base thereof. The outer surface of the adaptor may provide five raised contact points each having a surface which in use abuts an internal surface of a conical receiver, thus providing a five point kinematic mounting. In a second arrangement, the adaptor is generally cylindrical, with the probe mounted adjacent one end thereof. The adaptor may fit into a cylindrical receiver of an appropriate internal dimension. Four contact points may be provided around the outer surface of the adaptor to restrain rotation and translation with respect to each of two mutually perpendicular axes. Translation along the axis of the cylinder may be prevented by the provision of a fifth contact point on the other end of the adaptor. In a further alternative arrangement, the adaptor may take the form of a cylinder having an axial length less than the radius thereof, and an outwardly directed flange at one end thereof, the cylindrical part being received within an annular receiver. Two contact points may be provided on the peripheral surface of the cylinder, whilst a further three are provided on the flange to abut an end face of the receiver. Preferably the signal emitting and/or receiving means comprises an ultrasonic probe arrangement. An emitter and a receiver may each be mounted on the machine by way of respective separate assemblies independently movable with respect to each other. The invention also provides a material testing or working machine having signal emitting and/or receiving means, locating means therefor, and means receiving the locating means, and incorporating a mounting arrangement as described in any of the preceding eight paragraphs. An emitter and receiver may each be provided at respective ends of a single yoke arrangement such that the material to be tested may be passed therebetween. The initial calibration of the signal means may be carried out when the signal means is mounted on the machine; al ernatively the calibration may be performed separately before the signal means is so mounted. Embodiments of the invention will now be described for the purposes of illustration only with reference to the accompanying drawings in which: Fig. 1 is a diagrammatic perspective view of a first embodiment of a probe mount according to the invention; Fig. 2 is a diagrammatic perspective view of a second embodiment of a probe mount; Fig. 3 is a diagrammatic perspective view of a third embodiment of a probe mount; Fig. 4 is a plan view of a practical example of the mount of Fig. 3; and Fig. 5 is a diagrammatic sectional view on line V-V of Fig. 4. Fig. 1 illustrates a mounting arrangement for an ultrasonic probe 10. The probe 10 is mounted within a plug adaptor 12 in the form of a truncated cone, which is adapted to be received in a conical receiver (not shown) mounted on a ultrasonic testing machine. The axis of the conical receiver may be accurately aligned with the machine axes; the rotational symmetry of the receiver facilitating the manufacture and checking of this alignment. The axis of the wave signal of the probe 10 is defined with respect to three mutually perpendicular axes, designated X, Y, and Z in the drawings. In this case the Z axis corresponds to the probe axis. The peripheral surface of the plug 12 is so formed as to provide five raised contact points 14,16, 18,20,22 which provide for five point kinematic location of the plug 12 within the receiver. The points 14,16 are axially aligned but at opposite ends of the peripheral surface, and respectively restrain translation along the Y axis, and rotation about the X axis, whilst the points 18,20 are also axially aligned but at opposite ends of the peripheral surface, and are angularly spaced from the points 14, 16. The points 18, 20 respectively restrain translation along the X axis and rotation about the Y axis. The fifth point 22, angularly displaced from the other points, restrains translation along the Z axis. It will be appreciated that rotation about the Z axis does not affect the position of the axis of the ultrasonic signal in this case. A clamping force is provided along the Z axis by a suitable arrangement (not shown) to hold all five points in contact . The position of the probe 10 is initially adjusted relative to the plug 12 during a standard calibration procedure. Thereafter, the probe 10 may be accurately and repeatably mounted within the receiver by virtue of the kinematic mounting system provided. Fig. 2 shows an alternative form of plug 30 which is generally cylindrical in shape, the probe 10 being mounted at one end thereof. Contact points 32,34, axially aligned but at opposite ends of the peripheral surface of the plug 30, respectively restrain translation along the Y axis and rotation about the X axis, whilst contact points 36,38 axially aligned but at opposite ends, and angularly spaced from the points 32, 34 on the peripheral surface of the plug 30, restrain translation respectively along the X _ _ axis and rotation about the Y axis. A fifth contact point 40 axially aligned with the points 32, 34 but on the free end face of the plug 30 restrains translation along the Z axis. The plug is mountable within a complementary cylindrical receiver (not shown), and held by means of an appropriate clamping force directed to maintain the contact points in engagement. Fig. 3 shows a further plug 40 in the shape of an axially short cylinder having an outwardly directed flange 52 adjacent one end thereof. The plug 40 fits within an annular receiver 60. Three contact points 42,44,46 are spaced apart around the inner surface of the flange 52 to restrain rotation about the X and Y axes and translation along the Z axis. Two further points 48,50 spaced around a peripheral surface of the cylinder restrain translation along the X and Y axes. Clamping forces are provided by a suitable arrangement (not shown) to maintain the contact points in engagement. Figs. 4 and 5 show a practical example of the mount of Fig. 3. A plug 140 has a flange 152 part of which is cut away to permit access to and initial adjustment of kinematic contact points as described hereinafter. The plug 140 locates within a generally annular receiver 160. Three contact points 142, 144, 146 are provided in spaced locations adjacent the periphery of the flange, whilst a further two contact points 148,150 are spaced around a peripheral surface of the plug 140. Initial adjustment of the position of each contact point is carried out by means of a threaded bolt on which is carried the raised locating surface. Thereafter the plug may be positioned accurately and repeatably within the receiver and, by virtue of an initial calibration and adjustment of the probe within the plug, there is in turn permitted accurate and repeatable mounting of the probe within the receiver so that for, example, the ultrasonic axis is always aligned with the machine axis. The invention therefore provides a mounting arrangement which requires only an initial calibration and adjustment of the ultrasonic probe relative to the plug adaptor, and which thereafter permits accurate and repeatable mounting of the probe on the machine. Modifications may be made without departing from the invention. The plug and receiver may take different configurations from those described and shown. The choice of design for any particular application depends in part upon the available space around the probe. In addition, there may be utilized a four point or a six point kinematic mounting arrangement where circumstances permit For example, although it will generally be preferred to restrain translation along the axis of the ultrasonic probe ( the Z axis in the drawings), this may not be strictly necessary in every case. In addition, although rotation about the ultrasonic axis normally need not be restrained, a sixth point may be provided.

Claims: Claims : - 1. A mounting arrangement for use in a material testing or working machine, the arrangement comprising signal emitting and/or receiving means, and means for mounting the signal means on a material testing or working machine, the mounting means comprising locating means for the signal means and means for receiving the locating means on the machine, one of the receiving means and the locating means being adapted to provide for a repeatable kinematic mounting of the locating means on the receiving means, the signal means being capable of initial calibration and adjustment relative to the locating means whereby there is provided a repeatable kinematic mounting for the signal means on the machine. 2. An arrangement according to Claim 1, wherein the locating means includes contact points which provide for kinematic location of the locating means on the receiving means. 3. An arrangement according to Claim 1 or 2, wherein the kinematic mounting provides four, five or six degrees of restraint. 4. An arrangement according to Claim 1 or 2, wherein the kinematic mounting provides five degrees of restraint, with rotation being permitted about the axis of the emitted signal. 5. An arrangement according to any of the preceding Claims, wherein the receiving means has an axis of rotational symmetry, which coincides with the required - axis of propagation of the emitted signal . 6. An arrangement according to any of the preceding Claims, wherein the locating means and the receiving means respectively comprise a plug adaptor and a corresponding socket. 7. An arrangement according to Claim 6, wherein the adaptor has the form of a truncated cone with the signal means mounted adjacent the base thereof. 8. An arrangement according to Claim 7, wherein the outer surface of the cone may provide five raised contact points each having a surface which in use abuts an internal surface of a conical receiver, thus providing a five point kinematic mounting. 9. An arrangement according to Claim 6, whprein thp adaptor is generally cylindrical, with the signal mpans mounted adjacent one end thereof. 10. An arrangement according to Claim 9, wherein the adaptor fits into a cylindrical receiver of an appropriate internal dimension. 11. An arrangement according to Claim 9 or 10, wherein four contact points are provided around the outer sur¬ face of the adaptor to restrain rotation and translation with respect to each of two mutually perpendicular axes. 12. An arrangement according to Claim 11, wherein translation along the axis of the cylinder is prevented by the provision of a fifth contact point on the other end of the adaptor. 13. An arrangement according to Claim 6, wherein the adaptor has the form of a cylinder having an axial length less than the radius thereof, and an outwardly directed flange at one end thereof, the cylindrical part being received within an annular receiver. 14. An arrangement according to Claim 13, wherein two contact points are provided on the peripheral surface of the cylinder, whilst a further three are provided on the flange to abut, an end face of the receiver. 15. An arrangement according to any of the preceding Claims, wherein the signal emitting and/or receiving means comprises an ultrasonic probe arrangement. 16. An arrangement according to Claim 15, wherein an emitter and a receiver are each mounted on the machine by way of respective separate assemblies independently movable with respect to each other. 17. A material testing or working machine having signal emitting and/or receiving means, locating means therefor, and means receiving the locating means, and incorporating a mounting arrangement according to any of the preceding Claims. 18. A machine according to Claim 17, wherein an emitter and a receiver are each mounted on the machine by way of respective separate assemblies independently movable with respect to each other. 19. A machine according to Claim 17, wherein the emitter and the receiver are each provided at respective ends of a single yoke arrangement such that the material to be tested may be passed therebetween.

Inventors: BURY JAMES, BURY, JAMES
Applicants: LK LTD, LK LIMITED
Application year: 1992
Main classification: B06B3
IPC codes: B06B3, G01N29