GB2549519A

GB2549519A - A clamp

Info

Publication number: GB2549519A
Application number: GB1606951.0A
Authority: GB
Inventors: White Nick; Sillitoe Chris
Original assignee: Bio Pure Technology Ltd
Current assignee: Bio Pure Technology Ltd
Priority date: 2016-04-21
Filing date: 2016-04-21
Publication date: 2017-10-25
Also published as: KR102333964B1; CA3158648A1; JP2020173027A; PL3446020T3; DK3657060T3; HUE049851T2; FI3657060T3; BR112018070984A2; BR122022001151B1; US20220268382A1; KR20200130505A; BR112018070984B1; ES2801473T3; EP3446020B1; JP2020173026A; KR102205580B1; CN111396665A; EP3627029A1; JP2019519729A; EP3660380A1

Abstract

A clamp 2 for flanged tubes comprises first and second arcuate portions 4a, 4b hingedly connected together, and a ratchet mechanism for locking the two arcuate portions 4a, 4b in a closed position. The ratchet mechanism comprises a linear rack 18 provided with the second arcuate portion 4b and a pawl 28 provided with the first arcuate portion 4a for receiving the linear rack 18. The linear rack 18 comprises asymmetrical teeth and the pawl 28 comprises a plurality of fingers 36a, 36b which are biased into engagement with the teeth of the linear rack 18. A second aspect features the pawl 28 being formed from a module that is detachably connected to the first arcuate portion 4a. A third aspect features the arcuate portions 4a, 4b having a hinge arm defining a recess, a shaft received in the recess in a snap-fit manner, and a cam surface on one of the arcuate portions which contacts an opposing surface of the other arcuate portion during a transition between an assembly position and an open position to force the shaft towards the hinge arm. The linear rack 18 can comprise plural toothed paths, which can each be different.

Description

A CLAMP

The invention relates to a clamp, particularly but not exclusively for connecting flanged tubes or connectors for use in the bio-technology, pharmaceutical and food industries.

The ability to quickly and effectively make fluid-tight connections between sanitary fittings is particularly important in the bio-technology, pharmaceutical and food industries where the fluid being conveyed must be isolated from the external environment in order to retain the sterile conditions.

For example, a tri-clamp fitting may be employed to connect a pair of hose tail fittings which are each inserted in a hose. A tri-clamp fitting generally comprises two semicircular portions which are hingedly connected to one another. The free end of one of the semi-circular portions comprises a wingnut located on a bolt which can pivot relative to the semi-circular portion. The other semi-circular portion comprises a bifurcated portion which defines a slot that receives the bolt. The wingnut can be drawn into engagement with the bifurcated portion so as to lock the clamp in a closed position. The semi-circular portions comprise an inwardly facing tapered groove for drawing flanges of the hose tail fittings into sealing engagement, typically with a gasket therebetween.

In accordance with an aspect of the invention there is provided a clamp comprising: a first arcuate portion; a second arcuate portion hingedly connected to the first arcuate portion; and a ratchet mechanism for locking the first and second arcuate portions in a closed position; wherein the ratchet mechanism comprises a linear rack provided with the second arcuate portion and a pawl provided with the first arcuate portion for receiving the linear rack; wherein the linear rack comprises one or more asymmetrical teeth; wherein the pawl comprises a plurality of fingers which are biased into engagement with the teeth of the linear rack.

The linear rack may comprise a plurality of toothed paths each comprising one or more asymmetrical teeth; wherein each of the plurality of fingers are configured to engage with the teeth of one of the plurality of toothed paths.

The teeth of a first path of the plurality of toothed paths may differ from the teeth of a second path.

The dimensions of the teeth of the first path may differ from the teeth of second path.

The first path may comprise one or more teeth having a larger height than the teeth of the second path, wherein the teeth of the first path are positioned so as to provide tactile/audible feedback to a user to indicate an optimum clamping force.

First and second fingers of the plurality of fingers which engage the first and second paths respectively may be biased with different biasing forces.

The teeth of the first path may be offset from the teeth of the second path and/or first and second fingers which engage the first and second paths respectively may be offset from one another so that the first and second fingers engage alternately with the first and second toothed paths.

The plurality of toothed paths may comprise first and second paths which are provided on opposing surfaces of the linear rack.

The first and second paths may be provided on opposing lateral surfaces of the linear rack.

The position of at least one of the plurality of fingers can be changed to engage with a different one of the plurality of toothed paths.

The pawl may be formed by a module which is detachably connected to the first arcuate portion.

The module may be selected from a plurality of interchangeable modules.

The positions of the first and second fingers may differ for each of the plurality of interchangeable modules.

The plurality of fingers may be provided on a plurality of actuation buttons which are independently actuable.

The clamp may be formed from a reinforced polymeric materials.

In accordance with another aspect of the invention, there is provided a clamp comprising: a first arcuate portion; a second arcuate portion hingedly connected to the first arcuate portion; and a ratchet mechanism for locking the first and second arcuate portions in a closed position; wherein the ratchet mechanism comprises a linear rack provided with the second arcuate portion and a pawl provided with the first arcuate portion for receiving the linear rack; wherein the linear rack comprises one or more asymmetrical teeth and the pawl comprises a finger which is configured to engage with the teeth of the linear rack; wherein the pawl is formed by a module which is detachably connected to the first arcuate portion.

In accordance with another aspect of the invention, there is provided a clamp comprising: a first arcuate portion comprising a hinge arm which defines a recess; a second arcuate portion comprising a shaft which is received by the recess in a snap-fit so as to hingedly connect the first and second arcuate portions; wherein the clamp has an open position and a closed position and wherein the first and second arcuate portions are assembled in an assembly position; wherein the first or second arcuate portion comprises a cam surface which contacts an opposing surface of the other of the first and second arcuate portions during a transition between the assembly position and the open position so as to force the shaft towards the hinge arm.

For a better understanding of the invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:-

Figure 1 is a perspective view of a clamp according to an embodiment of the invention in a closed position;

Figure 2 is a perspective view of the clamp in an open position;

Figure 3 is a cross-sectional view of the clamp in the open position;

Figure 4 is an exploded view of the clamp;

Figure 5 is a cross-sectional view showing a ratchet mechanism of the clamp;

Figure 6 is a perspective view of the clamp in use;

Figure 7 is a cross-sectional view of the clamp in use;

Figure 8 is a perspective view of a clamp according to another embodiment of the invention in a closed position;

Figure 9 is a side view of the clamp of Figure 8; and

Figure 10 is a cross-sectional view showing a ratchet mechanism of the clamp of Figure 8.

Figures 1 and 2 show a clamp 2 according to an embodiment of the invention. The clamp 2 comprises a first, lower arcuate portion 4a and a second, upper arcuate portion 4b.

The first and second arcuate portions 4a, 4b are hingedly connected to one another. Specifically, the first arcuate portion 4a comprises a pair of hinge arms 6a, 6b which are spaced laterally from one another. The hinge arms 6a, 6b are arcuate and have extent which is slightly greater than 180°. The hinge arms 6a, 6b thus define a recess.

The second arcuate portion 4b is provided with a hinge lobe 8. A cylindrical stub shaft 10a, 10b projects from each lateral side of the hinge lobe 8. The stub shafts 10a, 10b are sized to be received within the recess defined by the hinge arms 6a, 6b to form a snap-fit connection. The first and second arcuate portions 4a, 4b are thus able to rotate between a closed position, as shown in Figure 1, and an open position, as shown in Figure 2.

As shown particularly in Figures 3 and 4, a radial, end surface of the hinge lobe 8 is provided with a pair of detent protrusions 12a, 12b which are angularly spaced from one another about the hinge lobe 8. The detent protrusions 12a, 12b interface with an edge 14 of the first arcuate portion 4a. Specifically, when opening the clamp 2, the detent protrusion 12a must be forced over the edge 14, such that the detent protrusions 12a, 12b straddle the edge 14, as is best shown in Figure 3. In this position, the detent protrusion 12a prevents the clamp 2 from closing and the detent protrusion 12b prevents the clamp 2 from opening further. Thus, the detent protrusions 12a, 12b retain the clamp in the open position to improve ease of use. The clamp 2 may, however, be opened further in order to release the stub shafts 10a, 10b from the hinge arms 6a, 6b in order to detach the second arcuate portion 4b from the first arcuate portion 4a by applying sufficient force to force the detent protrusion 12b over the edge 14. Similarly, the clamp can be closed by applying sufficient force to force the detent protrusion 12a over the edge 14. The detent protrusions 12a, 12b may be allowed to pass over the edge 14 through deformation of the clamp 2. For example, deformation may occur in one or more of: the detent protrusions 12a, 12b, edge 14, the stub shafts 10a, 10b and the hinge arms 6a, 6b. The detent protrusions 12a, 12b may be movable and biased outwardly by a biasing mechanism, such as a spring or the like, such that deformation of the detent protrusions 12a, 12b is permitted by deformation of the biasing mechanism.

As described previously, the first and second arcuate portions 4a, 4b are hingedly connected to one another by a snap-fit connection. The snap-fit connection is formed with the first and second arcuate portions 4a, 4b opened at an angle which exceeds that shown in Figure 2 such that both of the detent protrusions 12a, 12b are received on an interior side of the edge 14. In this position, the opening of the recess formed by the hinge arms 6a, 6b may sufficiently large to receive the stub shafts 10a, 10b with relatively little or no resistance. In this position, there is therefore significant laxity or slack in the hinged joint. However, when the clamp 2 is moved to the normally open position, with the detent protrusions 12a, 12b straddling the edge 14, the stub shafts 10a, 10b are held securely by the hinge arms 6a, 6b and this level of interference is maintained between the open and closed positions. Therefore, over the functional range of movement of the clamp 2, the hinged connection exhibits a very low amount of play. The transition of the hinged connection from a loose connection which enables easy assembly to a tight connection which improves user experience (exuding quality) may be achieved by providing a cam profile on one or more of the interface surfaces between the first and second arcuate portions 4a, 4b, such as one or more of the hinge surfaces formed by the hinge arms 6a, 6b and the stub shafts 10a, 10b and/or the end surface of the hinge lobe 8 and an opposing surface of the first arcuate portion 4a.

The loose connection during assembly may reduce the likelihood of spallation/particulate being removed during assembly, which is particularly important in a clean-room environment. Having a wide opening which easily receives the stub shafts 10a, 10b is also particularly useful where the clamp 2 is constructed from a stiff material, such as a reinforced polymeric material like glass-reinforced nylon.

The first and second arcuate portions 4a, 4b each comprise a semi-circular groove 16a, 16b. Side walls of the grooves 16a, 16b are angled with respect to one another such that the width of the groove tapers in a radial direction (i.e. the groove is narrower at a larger radius than at a smaller radius). In the closed position shown in Figure 2, the semi-circular grooves 16a, 16b of the first and second arcuate portions 4a, 4b meet to form a substantially continuous circular channel.

The distal, free ends of the first and second arcuate portions 4a, 4b are provided with a ratchet mechanism for locking the clamp 2 in the closed position. Specifically, the second arcuate portion 4b is provided with a tongue 18 (rack) which projects from the second arcuate portion 4b in a substantially circumferential direction. The tongue 18 comprises opposing lateral surfaces 20a, 20b which are each provided with one or more teeth.

The first arcuate portion 4a is provided with a receiving portion 22. The receiving portion 22 defines a cavity 24 (see Figure 3, particularly) which receives the tongue 18. The receiving portion 22 defines a slot 26 (see Figure 4, particularly) which opens outwardly and receives a separate pawl element 28. The pawl element 28 is detachably connected to the receiving portion 22 via a snap-fit connection. In particular, as shown in Figure 3, the receiving portion 22 comprises an upper ridge 30a and a lower ridge 30b which project into the slot 26. The pawl element 28 comprises complementary upper and lower grooves (not specifically labelled) formed in a body portion 32 of the pawl element 28 which receive the upper and lower ridges 30a, 30b to retain the pawl element 28 within the slot 26. The snap-fit connection between the pawl element 28 and the receiving portion 22 is not required to withstand in-use loads which are substantially perpendicular to the orientation of the snap-fit connection.

The pawl element 28 comprises a pair of actuation buttons 34a, 34b which are disposed at opposing lateral sides of the clamp 2.

As best shown in Figure 5, each of the actuation buttons 34a, 34b is provided with a finger 36a, 36b toward its lower end. The fingers 36a, 36b of the actuation buttons 34a, 34b are configured to engage with the teeth of the opposing lateral surfaces 20a, 20b of the tongue 18 respectively.

Each of the actuation buttons 34a, 34b is connected to the body portion 32 of the pawl element 28 by a torsion bar. The torsion bars bias the actuation buttons 34a, 34b so that the fingers 36a, 36b are biased towards one another and into engagement with the teeth of the opposing lateral surfaces 20a, 20b of the tongue 18. The fingers 36a, 36b may be drawn away from the tongue 18 by squeezing the upper ends of the actuation buttons 34a, 34b toward one another such that the actuation buttons 34a, 34b rotate about the torsion bars. This action generates a torque in the torsion bar which forces the fingers 36a, 36b back towards one another once the actuation buttons 34a, 34b are released. As shown in Figure 4, the receiving portion 22 is provided with a pair of angled recesses 38a, 38b which allow the actuation buttons 34a, 34b to be rotated as they are depressed.

The tongue 18 is curved along its length so that the teeth are kept parallel to the pawl element 28 during rotation of the second arcuate portion 4b about the hinge.

As shown particularly in Figure 7, the clamp 2 may be employed to connect a pair of hose tail fittings 40a, 40b used to join two sections of hose (not shown) together. The tail fittings 40a, 40b comprise a barb 42a, 42b which is inserted into the hose and a flange 44a, 44b.

In use, with the clamp 2 in the open position shown in Figure 2, the flanges 44a, 44b are received in the semi-circular groove 16a of the first arcuate portion 4a with a gasket seal 46 disposed therebetween. As shown, the opposing surfaces of the flanges 44a, 44b may be provided with circular grooves for receiving the gasket seal 46. The clamp 2 is then closed such that the second arcuate portion 4b is received over the flanges 44a, 44b. In this closed position, the tongue 18 is received in the receiving portion 22 and the teeth of the tongue 18 engage with the fingers 36a, 36b of the pawl element 28.

The teeth of the tongue 18 are asymmetrical such that the fingers 36a, 36b ride over the teeth as the tongue 18 is inserted into the receiving portion 22, but engage with the teeth if the tongue 18 is retracted from the receiving portion 22. The first and second arcuate portions 4a, 4b can therefore be squeezed together such that the teeth progressively pass the fingers 36a, 36b. Owing to the tapered geometry of the grooves 16a, 16b, this action causes the flanges 44a, 44b to be forced toward one another, compressing the gasket seal 46 disposed therebetween. The clamp 2 is therefore able to provide a fluid-tight seal between the tail fittings 40a, 40b and the ratchet mechanism ensures that the first and second arcuate members 4a, 4b are retained in the closed position at the desired level of compression.

In order to release the tail fittings 40a, 40b from the clamp 2, the actuation buttons 34a, 34b are depressed, as described previously, so that the fingers 36a, 36b no longer engage with the teeth thereby allowing the tongue 18 to be freely removed from the pawl element 28 and the receiving portion 22.

As described previously, the tongue is provided with teeth of both of the opposing lateral surfaces 20a, 20b. This provides a number of benefits and options for the clamp 2.

In particular, the teeth may differ from one side to the other in their number, position, spacing (i.e. frequency/pitch), dimensions (e.g. height), etc. For example, as shown in Figure 5, the lateral surface 20a may comprise a plurality of teeth having a fine pitch (akin to that of a cable-tie) and the opposing lateral surface 20b may comprise only a single tooth which is larger in height than the teeth of the lateral surface 20a. The single, larger tooth of the surface 20b may be positioned partway along the tongue 18 at a position which corresponds to an optimum clamping force. Therefore, in operation, this would give the user an initial experience similar to tightening a cable-tie followed by a loud, positive snap when the clamp is in the intended position. The fingers 36a, 36b of the pawl element 28 may also differ from one another in their geometry and/or biasing to enable and/or accentuate this functionality.

The tongue 18 may also contain a plurality of separate paths on one or both of the surfaces 20a, 20b which are offset from one another across the width of the surface 20a, 20b. For example, the surface 20b may contain a plurality of paths each comprising a single tooth for signifying that the clamp 2 has been adequately tightened, but located at different positions to correspond to the proper position for different uses. For example, the different paths may correspond to the requirements for different industries or may correspond to different tail fittings and/or gasket seals. The clamp 2 may be configured to use the required tooth path by selecting from a plurality of interchangeable pawl elements 28 which have fingers provided in the correct location to track along the required path. Alternatively, a single pawl element 28 may be used which can be modified to move the finger(s) into the correct position for the required path. A single, common design of the main clamp parts (i.e. the first and second arcuate portions 4a, 4b) can therefore cater for the many permutations of functionality offered by the configuration of the pawl element 28 (engineered to suit specific customer requirements).

In other embodiments, the teeth on the opposing lateral surfaces 20a, 20b may, however, be identical. Such an arrangement is beneficial in that the both of the actuation buttons 34a, 34b must be depressed in order to open the clamp 2. This redundancy avoids the clamp 2 being inadvertently released during service (including transportation and sterilisation of complete fluid-path assemblies in bags). The teeth on each of the opposing lateral surfaces 20a, 20b may also differ along the length of the surface 20a, 20b. Such an arrangement may be used to provide the tactile, audible feedback described previously at certain positions.

The opposing lateral surfaces 20a, 20b may also use identical tooth profiles, but which are offset from one another. This effectively allows the combined pitch/resolution of the surfaces 20a, 20b to be doubled, as the fingers 36a, 36b alternately engage with the teeth. Consequently, a larger, more robust tooth profile can be used and still achieve the same pitch/resolution as a single-sided rack. Alternatively, the fingers 36a, 36b may be offset from one another to achieve the same effect. This could also be achieved using a single actuation button carrying a pair of offset fingers which engage a single toothed rack.

This may be particularly beneficial when using certain materials, such as glass-reinforced nylon. In particularly, such materials may limit the effective engagement area of the teeth and therefore ultimately impose a minimum pitch of the teeth since the tooth profile should avoid sharp edges and therefore incorporate a slightly rounded edge. Moreover, a larger, more robust tooth profile is less likely to abrade and generate particulate contamination during normal operation.

Retaining the ability to fine-tune the gasket sealing pressure allows a user to change (particularly, tighten) the pressure slightly after sterilisation (especially following autoclaving).

The ratchet mechanism is both Gamma stable and autoclave stable such that its performance is not compromised by any material degradation due to repeated cycles of cleaning and subsequent sterilisation by autoclaving or gamma irradiation. The tongue 18 is resistant to creep/relaxation in use (especially during autoclaving in the assembled position) by virtue of the glass fibre reinforcement in the material.

The use of interchangeable pawl elements 28 which are detachably connected to the clamp allows the clamp to be tailored to specific applications and users. For example, in certain applications, the actuation buttons 34a, 34b may be removed or concealed such that the clamp can only be released by cutting, breaking or otherwise opening part of the pawl element. The clamp may require a specific tool for this purpose to prevent unauthorised release of the clamp. The pawl elements 28 may also be different colours to reflect a customer colour scheme or to allow differentiation between clamps performing different functions. The pawl elements 28 can also be branded for specific customers and can include technical information, such as the date of manufacture.

Although not shown, the clamp may also provide visual as well as audible/tactile feedback regarding the position of the ratchet mechanism. For example, a simple scale of numbers may be used that are revealed to correspond with the position of the clamp.

The linear rack has been described as having teeth located on a lateral surface of the clamp. However, it will be appreciated that the teeth could be perpendicular to this and located on radial surfaces of the clamp. The teeth may also be provided only on one surface, rather than opposing surfaces. With this arrangement, a single set of teeth may be engaged by two fingers carried by a single actuation button to improve resolution or two separate actuation buttons (with the fingers offset laterally or along the length of the rack) to provide redundancy, as described previously. The rack may also comprise a plurality of toothed paths which are offset from one another (along the same surface, rather than on opposing surfaces, as described previously) and engaged by separate fingers carried by a single actuation button or multiple actuation buttons in order to provide the tactile feedback mechanism described above. The adjacent toothed paths may be formed by a single set of teeth and only notionally divided into separate paths based on the passage of the fingers along the rack.

The tactile/audible feedback may be generated by using enlarged teeth, as described, or may alternatively be generated by controlling the biasing force of the fingers.

The or each actuation button may carry a plurality of fingers which simultaneously engage with the teeth to provide improved engagement.

Although the pawl element 28 been described as using a torsion bar design, it will be appreciated that other arrangements may be used, such as a cantilever design. In certain applications, the pawl element 28 may also be integrally formed with the first arcuate member 4a.

Figures 8 to 10 show a clamp 102 according to another embodiment of the invention. The clamp 102 is similar to the clamp 2 described previously in many respects, but differs primarily in that it does not include a separate pawl element which is detachably connected to the clamp.

The clamp 102 again comprises a first, lower arcuate portion 104a and a second, upper arcuate portion 104b which are hingedly connected to one another in a similar manner to that described for the clamp 2.

As described for the clamp 2, the clamp 102 comprises a ratchet mechanism for locking the clamp 102 in the closed position. Specifically, the second arcuate portion 104b is provided with a tongue 118 (rack) which comprises opposing lateral surfaces 120a, 120b which are each provided with one or more teeth. The first arcuate portion 104a is provided with a receiving portion 122. The receiving portion 122 defines a cavity 124 (see Figure 10) which receives the tongue 118. Each lateral side of the receiving portion 122 comprises a pawl portion 134a, 134b. The pawl portions 134a, 134b are connected to the receiving portion 122 only at their lower ends. The pawl portions 134a, 134b are therefore cantilevered and are allowed to pivot about their lower ends via a thinned section 148a, 148b which forms a hinge (see Figure 10). A release tab 150a, 150b protrudes perpendicularly from each pawl portion 134a, 134b.

The release tabs 150a, 150b are positioned towards the free end of the pawl portions 134a, 134b and thus are spaced from the hinged ends.

As shown in Figure 10, each of the pawl portions 134a, 134b is provided with a pair of fingers 136a, 136b (only one finger may be used in other embodiments) which are spaced from the hinged ends of the pawl portion 134a, 134b. The fingers 136a, 136b are configured to engage with the teeth of the opposing lateral surfaces 120a, 120b of the tongue 118 respectively.

The free ends of the pawl portions 134a, 134b are biased towards one another so that the fingers 136a, 136b engage with the teeth of the opposing lateral surfaces 120a, 120b of the tongue 118. The fingers 136a, 136b may be drawn away from the tongue 18 by pivoting the pawl portions 134a, 134b about the hinged ends. The clamp 102 may be held such that the operators thumb is positioned under the lower arcuate portion 104a, and the index and middle finger are on top of the release tabs 150a, 150b. The release tabs 150a, 150b may be pulled down so that they pivot about the hinged ends, thereby drawing the fingers 136a, 136b away from one another and out of engagement with the teeth of the tongue 118 so that the clamp 102 can be opened. The pawl portions 134a, 134b are resilient such that the fingers 136a, 136b are forced back towards one another once the release tabs 150a, 150b are released.

As shown in Figure 8, the receiving portion 122 may be provided with an aperture 152 formed in its radial, end surface which allows the radial, end surface of the tongue 118 to be viewed when it is received within the receiving portion 122. The radial, end surface of the tongue 118 may comprise a graduated scale along its length which is visible through the aperture 152 and thus provides an indication of the position of the tongue 118 within the receiving portion 122 and thus the relative positions of the arcuate portions 104a, 104b. The scale can therefore be used to ensure that the clamp 102 has been closed sufficiently.

To avoid unnecessary duplication of effort and repetition of text in the specification, certain features are described in relation to only one or several aspects or embodiments of the invention. However, it is to be understood that, where it is technically possible, features described in relation to any aspect or embodiment of the invention may also be used with any other aspect or embodiment of the invention.

It will be appreciated that the first and second arcuate portions need not be semicircular and that additional (arcuate or non-arcuate) portions may be disposed between the first and second arcuate portions. The second arcuate portion may therefore be hingedly connected to the first arcuate portion via one or more additional portions.

The invention is not limited to the embodiments described herein, and may be modified or adapted without departing from the scope of the present invention.

Claims

1. A clamp comprising: a first arcuate portion; a second arcuate portion hingedly connected to the first arcuate portion; and a ratchet mechanism for locking the first and second arcuate portions in a closed position; wherein the ratchet mechanism comprises a linear rack provided with the second arcuate portion and a pawl provided with the first arcuate portion for receiving the linear rack; wherein the linear rack comprises one or more asymmetrical teeth; wherein the pawl comprises a plurality of fingers which are biased into engagement with the teeth of the linear rack.

2. A clamp as claimed in claim 1, wherein the linear rack comprises a plurality of toothed paths each comprising one or more asymmetrical teeth; wherein each of the plurality of fingers are configured to engage with the teeth of one of the plurality of toothed paths.

3. A clamp as claimed in claim 2, wherein the teeth of a first path of the plurality of toothed paths differs from the teeth of a second path.

4. A clamp as claimed in claim 3, wherein the dimensions of the teeth of the first path differs from the teeth of second path.

5. A clamp as claimed in claim 4, wherein the first path comprises one or more teeth having a larger height than the teeth of the second path, wherein the teeth of the first path are positioned so as to provide tactile/audible feedback to a user to indicate an optimum clamping force.

6. A clamp as claimed in any of claims 3 to 5, wherein first and second fingers of the plurality of fingers which engage the first and second paths respectively are biased with different biasing forces.

7. A clamp as claimed in any of claims 3 to 6, wherein the teeth of the first path are offset from the teeth of the second path and/or first and second fingers which engage the first and second paths respectively are offset from one another so that the first and second fingers engage alternately with the first and second toothed paths.

8. A clamp as claimed in any of claims 2 to 7, wherein the plurality of toothed paths comprise first and second paths which are provided on opposing surfaces of the linear rack.

9. A clamp as claimed in claim 8, wherein the first and second paths are provided on opposing lateral surfaces of the linear rack.

10. A clamp as claimed in any of claims 2 to 9, wherein the position of at least one of the plurality of fingers can be changed to engage with a different one of the plurality of toothed paths.

11. A clamp as claimed in any preceding claim, wherein the pawl is formed by a module which is detachably connected to the first arcuate portion.

12. A clamp as claimed in claim 11, wherein the module is selected from a plurality of interchangeable modules.

13. A clamp as claimed in claim 12, wherein the positions of the first and second fingers differ for each of the plurality of interchangeable modules.

14. A clamp as claimed in any preceding claim, wherein the plurality of fingers are provided on a plurality of actuation buttons which are independently actuable.

15. A clamp as claimed in any preceding claim, wherein the clamp is formed from a reinforced polymeric materials.

16. A clamp comprising: a first arcuate portion; a second arcuate portion hingedly connected to the first arcuate portion; and a ratchet mechanism for locking the first and second arcuate portions in a closed position; wherein the ratchet mechanism comprises a iinear rack provided with the second arcuate portion and a pawi provided with the first arcuate portion for receiving the iinear rack; wherein the iinear rack comprises one or more asymmetricai teeth and the pawi comprises a finger which is configured to engage with the teeth of the iinear rack; wherein the pawi is formed by a moduie which is detachabiy connected to the first arcuate portion.

17. A damp comprising: a first arcuate portion comprising a hinge arm which defines a recess; a second arcuate portion comprising a shaft which is received by the recess in a snap-fit so as to hingediy connect the first and second arcuate portions; wherein the damp has an open position and a closed position and wherein the first and second arcuate portions are assembled in an assembly position; wherein the first or second arcuate portion comprises a cam surface which contacts an opposing surface of the other of the first and second arcuate portions during a transition between the assembly position and the open position so as to force the shaft towards the hinge arm.

18. A clamp substantially as described herein with reference to and as shown in the accompanying drawings.