GB2528165A - Apparatus for use in a suspension system of an MRI scanner - Google Patents

Abstract

A cylindrical metal billet or drum 11 with a circular cross section 18 has a channel 16 cut or machined into its face, the channel opening at both ends on the side surface of the billet. A composite suspension band (17 Fig 3) is inserted into the channel so that the ends of the band extend out of the open ends of the channel and the open sides of the channel are sealed using a retaining cap (16 Fig 3), which may be held in place by a screw or bolt (15 Fig 3). The cap extends over the face of the channelled billet to prevent the band coming out. There may be a plurality of channels (26, 26 Fig 6). A threaded shank (12 Fig 3) may also be attached to the metal billet for attachment to an MRI scanner.

Description

Apparatus for Use in a Suspension System of an MRI Scanner The present invention relates generally to attachments for composite suspension bands and finds particular, although not exclusive, utility in suspension systems for MRT scanners.

Superconducting magnets within an MRI scanner are often housed in a liquid helium tank, and supported by composite straps (i.e.. suspension bands) for high cryostat mechanical and thermal peormance. The suspension system for a superconducting magnet performs tvo essential functions: it resists internally and externally generated structural loads to ensure that position is stable over the operating life, of the magnet; and it limits conduction of heat from the outside world.

The conventional method of securing a composite suspension hand is with a clevis, typically of the kind shown in figures 1 and 2. The body of such a clevis is a substantially Y-shape item, machined as a single piece, with a spool extending between the at-ms of the Y-shape and held in place by a pin. Multiple machining operations are required to manufacture such devises, and a large amount of material must he machined away to form the overall Y-shape, and is thus wasted. these items are usually exposed to high stresses arid arc therefore oftcn rianufaeturcd from expensive, high grade material; for example austenite nickel-chromium-based superalloys (e.g. Tnconel ERTIVO), titanium and austenitic stainless steels (e.g. austenite).

Alternative manufacturing techniques for devises that avoid waste of large quantities of high grade material involve machining individual components (e.g. the tsvo arms and the body of the i'-shape as three separate parts) and connecting them together; however, this process produces an inherently weak component, and is preferably avoided.

According tc the present invention, there is provided a method of manufacturing a connector for use in a suspension system of an MRI scanner, the method comprising the steps of: providing a metal billet having a substantially circular cross-section; machining a channel in a substaiffially circular face of the metal billet, the channel having a substantially unifonn radius of curvature, and the channel opening at both ends on a substantially curved face of the metal billet; inserting a suspension band into the channel, such that the suspension band extends out of the open ends of the channel; and sealing an open side to the channel by providing a cap that extends over substartially the entire substantially circUlar face of the metal billet in which the channel is machined.

Tn this way, a connector may he produced with a reduced machining time, and with less waste due to the reduction in the amount of material that is required to be removed. In addition, the overall size and/or extent of the connector may be reduced by manufacturing the. support structure and suspension band supporting part (i.e. the par hitherto formed by the 1-shape portion of the clevis and the spool) as a single component. Furthermore, the above-mermoned manufacturing technique requires a much simpler manufacturing technique.

The metal billet may have a substantially cylindrical form, and may be of any suitable metal, for instance as discussed above with respect to known devises, the metal billet may have a diameter of between approximately 20mm and 80mm. in particular between approximately 30mm and 70mm, more particularly approximately 40mm, 50mm or 60mm.

A body of the connector may be formed by cuffing it from the metal billet in a direction that preserves the diameter but reduces the axial length of the billet. The cap may be formed in a similar manner. the thickness of the body of the connector may be bctwccri approxirrratcly 8mm arid 70rnrri, in l3actlat lJcrt\1cer ipproxirrvitely I Orrirri and 60mm, for instance 12mm or 50mm.

The suspension band may comprise a closed loop of material, for instance planar material. In particular the suspension band may be a composite material, the composite material may comprise carbon (e.g. graphite), glass, alumina, basalt, and/or aramid fibres, especially para-ararnid fibre (e.g. Kevlar (R'tM)). and/or metal. However, the present invention may he used with any band material for example composite or metallic.

The machining may comprise numerical control, for instance computer! computerised nunierical control. The machining may comprise using a mill / milling machine, lathe, plasma cutter, electric discharge machine, drill and/or any other suitable machining tool.

The channel may have a radius of curvature that varies along its length by up to 20%, in particular 10%, more particularly 5%. The channel may have a radius of curvature that is substantially constant along up to 70% of its length, in particular up to 80%, more particularly up to 90%. the radius of curvature may he hetiveen 2ipproxinlitely 8mm and 40mm, in particular hertveen approximately 10mm and 33mm.

more particularly approximately 1 2.3nun, 1 7nimn, 20mm or 26mm. The channel may be curved and have a radius of curvature on an inner surface thereof that is less than the radius of curvature on an outer surface thereof. The channel may have a substantially constant width between the inner and outer surface.

The channel may have a depth that is substantially equal to the width of the suspension band to be inserted therein. For instance, the depth may be beveen approximately 2mm and 35mm, in particular lietween approximately 3mm and 30mm, for instance, approximately 4mm, 8mm, 12mm, 18mm, 24mm, 34mm. The band may have a thickness of bertveen 1.5mm and 10mm, in particular bertveen approximately 1.3mm and 5mm, more particularly approximately 3mm.

The cap may have a diameter within appro>dmately 20% of that of the billet, in particular within approximately 10%, more particularly within approximately 10%. The cap may have a lip that extends around a perimeter of the billet, and may fit around the curved surface of the billet. Alternatively, the cap may be formed from a portiot of the billet. The cal) may he attached to the billet with a bolt, screw, rivet or any other suitable fixing. the cap may have a thickness of bertveen approximately 1.5mm and 1 Orrirn, in ptrticular between approximately 2rrirn arid 8rnrri, more particularly approximately 3mm or 7mm.

The method may further comprise: machining a further channel in the substantially circular face of the metal billet, the further channel having a substantially uniform radius of curvature, and the further channel opening at both ends on the substantially curved face of the metal billet; and inserting a further suspension band into the channel, such that the further suspension band extends out of the open ends of the further channel. In this way, the method may provide a way of connecting two suspension bands together.

Alternatively, the method may further comprise connecting a shank to the metal billet, fur instance the substantially curved surface of the billet, for subsequent connection to an MRI scanner. In this way, the method may provide a way of connecting a suspension band to an vllhI scanner. The shank may have a diameter of between approximately 4mm and 40mm, in particular between approximately 5mm and 30mm, for instance approximately 6mm, lOmni, 13mm, 20mm, 25mm or 30mm. the shank may he, at least partially, threaded to allow connection of a nut or other securing means thereto, and/or to allow threadably connection to the billet. The shank may have a length of between approximately 40 and 21)0mm, in particular between approximately 50mm and 150mm, for instance 60. 70, 80, 90, 100, 120 or 140mm.

The method may further comprise machining a recess in the biUet for receiving the shank and/or a fixing for the cap therein.

The billet may have an axial length (along its axis of rotitional symmnetrv of beveen approximately 8mm and 40mm, in particular betveen approximately 10mm and 34mm, for instance approximately 1 2mm, 25mm or 32mm.

The above and other characteristics, features and advantages of the present invenflon \vill become apparent from the follo\ving detailed description, taken in conjunction xvith the accompanying dra\vings, \vhich illustrate, by xvay of example, the principles of the invention. This description is given for the sake of example only.

without limiting the scope of the invention. The reference figures quoted below refer to the attached drawings.

Figure 1 is a perspective view of a prior art clevis.

Figure 2 is an exploded view of the clevis of figure 1.

Figure 3 is a perspective view of a connector for use in a suspension system of art MIt! scanner.

Figure 4 is an exploded view ofa connector similar to that shown in figure 3.

Figure 5 is a perspective vie\v of an alternative connector for use in a suspension system of an MRI scanner.

Figure 6 is an exploded view of the connector shown in figure 5.

The present invention \vill be described with respect to certain drawings but the invention is not limited thereto hut only by the claims. The drawings described are only schematic and are non-limiting. Each drawing may not include all of the features of the invention and therefore should not necessarily he considered to be an embodiment of the invention. Tn the drawings, the size of some of the elements may be exaggerated and not drawn to scale for illustrative iMirposes. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the invention.

Furthermnore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar den ents and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to he understood that the terms so used are interchangeable under appropriate circumstances and that operation is capable in other sequences than described or illustrated herein.

Moreover, the terms top, bottom, over, under and the like in the description and the claims are used for descriptive pnposes and not necessarily for describing relative posos It is to be understood that the terms so used are interchangeable under appropriate circumstances and that operation is capable in other orientations than described or illustrated herein.

Tt is to be noticed that the term "compnsing" used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. it is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof Thus, the scope of the expression "a device comprising means and B" should not be limited to devices consisting only of components A and B. Tt means that with respect to the present invention, the only relevant components of the device are A and B. Reference throughout this specification to "an embodiment" or "an aspect" rricaris that a p2titicul2ir feature, structure or characteristic dcscribcd in coruiectioni with the embodiment or aspect is included in at least one embodiment or aspect of the present invention. thus, appearances of the phrases "in one embodiment", "in an embodiment", or "in an aspect" in various places throughout this specification are not necessarily all referring to the same embodiment or aspect, but may refer to different embodiments or aspects. Furthermore, the particular features, structures or characteristics of any embodiment or aspect of the invention may he combined in any suitable manner, as would he apparent to one of ordinary skill in the art from this

disclosure, in one or more embodiments or aspects.

Similarly, it should be appreciated that in the description various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Moreover, the description of any individual drawing or aspect should not necessarily he considered to he an embodiment of the invention. Rather, as the following claims reflect, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description arc hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

Furthermore, wlnle some embe'diments described herein include some features included in other embodiments, combinations of feature.s of different embodiments are.

meant to be within the scope of the invention, and form yet further embodiments, as will be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

In the description provided herein, numerous specific details are set forth.

However, it is understood that embodiments of the invention may be practised without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of

this description.

In the discussion of the invention, unless stated to the contrary, the disclosure of alternative values for the upper or lower limit of the permitted range of a parameter, coupled with an indication that one of said values is more highly preferred than the other, is to be construcd as an implied statement that each intenriediatc value of said parameter, lying between the more preferred and the less preferred of said alternatives, is itself preferred to said less preferred value and also to each value lying bettveen said less preferred value and said intermediate value.

The use of the term "at least one" may mean only one in certain circumstances.

The principles of the invention will now be described by a detailed description of at least one draxving relating to exemplary features of the invention. It is clear that other arrangements can he configured according to the knowledge of persons skilled in the art without departing from the underlying concept or technical teaching of the invention, the invention being limited only by the terms of the appended claims.

Figure 1 is a perspective view of a known clevis design. The body 1 of the clevis is machined from a billet asa single Y-shape component, comprising a shank and opposing side walls. The shank is threaded, for attaclunent to a housing of an i'vlIftI scanner or similar device. The side walls hold between them a drum 3, held in place by a locking pin 3, which supports a composite band 7.

Figure 2 is an exploded view of the known clevis of hgure 1, showing the Y-shape body 1, the drum 3. and hcking pin 5. The composite band 7 has been omitted for danty.

Figure 3 is a perspective view of a connector for use in a suspension system of an MRT scanner. The connector compnses a body 11, in the form of a squat cyhndrical part (i.e. with an axial length less than a diameter, machined directly from a metal billet.

A separate shank 12 is threaded at both ends, on an end distal from the body ii it is threaded for attachment to a housing of an MRT scanner of simfiar device; nut 14 is located on the shank 12 to indicate this. On an end proximal to the body 11 the shank 12 is threaded for insertion and cooperation with a threaded hole machined into an exterior curved surface of the body 11. A composite band 17 is coupled to the body 11, and is held in place by a cap 16, which is secured in place by a screw/bolt 15.

The connector shown in figure 4 as an exploded view differs from the connector in figure 3 on'y in terms of its abseilute proportions. On a substantially flat surfbce of the body 11 a channd 16 has been machined to eave a band supporting part 13 of the body 11 and a structura' part 18 of the body.

Figure 5 is a perspective view of an alternative connector for use in a suspension system of art Miti scanner. Ihe connector corripnses a body 21 iii the form of a squat cyhndrica] part machined direcfly from a mcta billet. Two composite bands 27, 27' are each coupled to the body 11, and held in place by a cap 26, which is secured in place by tvo screws/bolts 25, 25'.

As shown in figure 6, on a substantially flat surface of the body 21, rtvo channels 26, 26' are cut to leave band supporting parts 23, 23' of the body 11 and a structural part 28 of the body.