Driving band

Abstract

A driving band (100) comprising a shape memory alloy material. The shape memory alloy may be configured to expand from a first diameter (D1) to a second diameter (D2) when raised from a first temperature (T1) to a second temperature (T2). The shape memory alloy is configured to contract from the second diameter (D2) to the first diameter (D1) when lowered from the second temperature (T2) to the first temperature (T1).

Description

FIELD

[0001] The present disclosure relates to a driving band.BACKGROUND

[0002] Driving bands, also known as rotating bands, are critical components in the design and functionality of artillery shells. They extend around the circumference of the shell so that when fired, the pressure from burning propellant forces the driving band into the rifling of the gun barrel, creating a seal that prevents propellant gases from escaping past the shell. This engagement with the rifling also imparts a spin to the shell, stabilizing its flight and improving accuracy. Figures 1, 2 (of PCT / GB2014 / 052526) illustrate an example of the related art.

[0003] The driving band may be fitted to the shell in a number of ways (for example using a swaging process). Unfortunately, such processes change the material properties of the driving band in unpredictable ways, and hence modelling the interactions between the driving band and the gun barrel may be inaccurate, making their performance difficult to predict without lengthy and expensive physical testing.

[0004] Hence a driving band with material properties that can be defined after being fitted to an artillery shell is highly desirable.SUMMARY

[0005] According to the present disclosure there is provided an apparatus and method as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and the description which follows.

[0006] Accordingly there may be provided a driving band (100) comprising a shape memory alloy material.

[0007] The shape memory alloy may be configured to expand from a first diameter (D1) to a second diameter (D2) when raised from a first temperature (T1) to a second temperature (T2). The shape memory alloy may be configured to contract from the second diameter (D2) to the first diameter (D1) when lowered from the second temperature (T2) to the first temperature (T1).

[0008] The driving band (100) may have a material composition such that the material properties of the shape memory alloy are a function of the temperature of the shape memory alloy, such that at the first temperature (T1), prior to being raised to the second temperature (T2), the shape memory alloy has a first set of material properties; and after being lowered from the second temperature (T2) to the first temperature (T1), the driving band (100) has the first set of material properties.

[0009] The shape memory alloy may comprise a decoppering agent.

[0010] The shape memory alloy may comprise copper, nickel, iron, graphite and tin.

[0011] The shape memory alloy may comprise 50-60% copper, 15-20% nickel, 5-10% iron, 0.5-1.5% graphite and 1-3% tin.

[0012] No more than 1% shape memory alloy may be comprised of a wax binder.

[0013] The driving band (100) may comprise a radially inner surface (102) which defines a first engagement feature (104) for engagement with a second engagement feature (204) on a main body (202) of an artillery shell (200).

[0014] The first engagement feature (104) and the second engagement feature (204) may be configured to couple to one another so as to allow the driving band (100) to slide relative to the shell (200) along its longitudinal axis (208).

[0015] The first engagement feature (104) and the second engagement feature (204) may be configured to couple to one another so as to prevent relative rotation of the driving band (100) and shell (200) around the longitudinal axis (208).

[0016] The first engagement feature (104) may be provided as a channel (106) which extends in an axial direction from a first edge (110) of the driving band (100) to a second edge (120) of the driving band (100).

[0017] The driving band (100) may be formed using a powder metallurgy process.

[0018] There may be provided a shell (200) for an artillery weapon.

[0019] The shell (200) may comprise a main body (202) which defines, and extends along, a longitudinal axis (208) from a leading edge end (220) to a trailing edge end (222).

[0020] The shell (200) may comprise a driving band (100) according to the present disclosure which extends around the circumference of the main body (202) at a location between the leading edge end (220) and the trailing edge end (222).

[0021] The main body (202) may define a recess (240) which extends around the circumference of the main body (202). The driving band (100) may be located in the recess (240).

[0022] The second engagement feature (204) may be provided in the recess (240).

[0023] The second engagement feature (204) may be provided as a protrusion (210) which extends radially away from the main body (202).

[0024] The second engagement feature (204) may be provided as a protrusion (210) which extends in an axial direction along the longitudinal axis (208).

[0025] The second engagement feature (204) may be provided as a protrusion (210) configured for engagement with the first engagement feature (104) of the driving band (100).

[0026] The first engagement feature (104) and the second engagement feature (204) may be configured to allow the driving band (100) to slide relative to the shell (200) along the longitudinal axis (208).

[0027] The first engagement feature (104) and the second engagement feature (204) may be configured to prevent relative rotation of the driving band (100) and the shell (200) around the longitudinal axis (208).

[0028] The trailing edge end (222) of the main body (202) may define a first coupling feature (230).

[0029] The shell (200) may comprise a tail unit (300).

[0030] The tail unit (300) may define a second coupling feature (330).

[0031] The first coupling feature (230) and the second coupling feature (330) may be configured to couple the main body (202) and the tail unit (300) to one another.

[0032] The recess (240) may be defined by, and extend between, a first location feature (242) provided on the main body (202) and a second location feature (342) provided on the tail unit (300).

[0033] The driving band (100) may abut the first location feature (242) and the second location feature (342).

[0034] There may be provided a method of assembly of a shell (200) for an artillery weapon. The shell (200) may comprise a main body (202) which defines, and extends along, a longitudinal axis (208) from a leading edge end (220) to a trailing edge end (222). The main body (202) may define a recess (240) which extends around the circumference of the main body (202). The shell (200) may comprise a driving band (100) configured to extend around the circumference of the main body (202) between the leading edge end (220) and the trailing edge end (222).

[0035] The method may comprise controlling the temperature of the driving band (100) so that it is at a temperature greater than the main body (202) such that the driving band (100) increases in diameter.

[0036] The method may comprise sliding the driving band (100) onto the main body (202).

[0037] The method may comprise locating the driving band (100) in the recess (240).

[0038] The method may comprise controlling the temperature of the driving band (100) so that it is at the same temperature as the main body (202) such that the driving band (100) decreases in diameter to engage with the main body (202).

[0039] The trailing edge end (222) of the main body (202) may define a first coupling feature (230). A first location feature (242) may be provided on the main body (202). The shell (200) may comprise a tail unit (300). The tail unit (300) may define a second coupling feature (330). A second location feature (342) may be provided on the tail unit (300). The recess (240) may be defined by, and extend between, a first location feature (242) provided on the main body (202) and a second location feature (342) provided on the tail unit (300). The driving band (100) may abut the first location feature (242) and the second location feature (342). The method may comprise the step of locating the driving band (100) such that it abuts the first location feature (242).

[0040] The method may comprise the step of coupling the main body (202) and the tail unit (300) to one another by coupling the first coupling feature (230) and the second coupling feature (330).

[0041] The main body (202) and the tail unit (300) may be coupled to one another by coupling the first coupling feature (230) and the second coupling feature (330) such that the recess (240) is defined by, and extends between, the first location feature (242) provided on the main body (202) and the second location feature (342) provided on the tail unit (300).

[0042] The main body (202) and the tail unit (300) may be coupled to one another by coupling the first coupling feature (230) and the second coupling feature (330) such that the driving band (100) abuts the first location feature (242) and the second location feature (342).

[0043] The driving band (100) may further comprise a radially inner surface (102) which defines a first engagement feature (104) for engagement with a second engagement feature (204) on the main body (202) of the shell (200).

[0044] The method may comprise providing the second engagement feature (204) in the recess (240) before the driving band (100) is located in the recess (240) and then sliding the driving band (100) onto the main body (202) to engage the first engagement feature (104) and the second engagement feature (204) so as to prevent relative rotation of the driving band (100) and the shell (200) around the longitudinal axis (208).

[0045] Hence there may be provided a driving band with material / mechanical properties which are unchanged by being fitted to an artillery shell assembly.BRIEF DESCRIPTION OF THE FIGURES

[0046] Embodiments of the invention will now be described by way of example only with reference to the figures, in which: Figure 1 shows an exploded view of an artillery shell of the related art; Figure 2 shows a sectional view of an artillery shell of the related art; Figure 3 shows a perspective view of a first example of a driving band according to the present disclosure; Figure 4 shows an end on view of a second example of a driving band according to the present disclosure; Figure 5 shows a side view of part of a shell assembly according to the present disclosure; Figures 6 to 11 show side sectional views of components of a shell according to the present disclosure during stages in the assembly of the shell. DETAILED DESCRIPTION

[0047] The present disclosure relates to a driving band 100 comprising a shape memory alloy material. The present disclosure relates to a driving band 100 for an artillery shell 200. The present disclosure relates to a shell (for example an artillery shell) configured to be fired from a barrel of a gun. The present disclosure relates to a shell comprising a driving band 100. The present disclosure relates to a method of assembly of a shell 200 for an artillery weapon. The present disclosure relates to a method of assembly of a shell 200 comprising a driving band 100 for an artillery weapon.

[0048] Artillery shells comprise a main body (typically referred to as a "shell") which may be hollow and contain a payload, for example (but not limited to) a high-explosive, incendiary or illumination payload. They may also comprise a fuse that ignites the payload. In some examples the shell may additionally comprise a propellant, which is a separate charge that ignites to propel the shell out of a gun barrel. In other examples the shell may be provided separately to a propellant (e.g. the shell and propellant are provided separately in the weapon from which the shell is fired.)

[0049] A driving band (also known as a rotating band), is a band of relatively soft metal which extends around the base of a projectile (e.g. an artillery shell) for engagement with the inner surface (e.g. rifling) of a gun barrel operable to receive the projectile. When the shell or weapon is fired, the driving band is forced into engagement with the inner circumference (e.g. rifling). This helps to centre the projectile, thereby improving its alignment with the gun barrel, and hence improving accuracy of delivery of the projectile. In examples where rifling is present on the inside surface of the barrel, the driving band may engage with the rifling to spin the projectile, stabilizing it in flight. The driving band also seals the bore of the barrel by preventing the gases from the burning propellant from escaping past the projectile, thereby enabling efficient propulsion.

[0050] The driving band 100 of the present disclosure may be fitted to the outer circumference of a shell body, either to its outer diameter, or located within a groove or recess that extends around and is defined by the shell body.

[0051] Figure 11 illustrates a shell assembly 200 according to the present disclosure, including a driving band 100 of the present disclosure. However, the driving band 100 of the present disclosure may alternatively be fitted to (and hence form part of) a shell of a conventional design.

[0052] A shape memory alloy (SMA) is a type of metal that can return to its original shape after being deformed due to thermal expansion.

[0053] Figures 3, 4 illustrate an example of a driving band 100 according to the present disclosure. The driving band 100 may be provided in a shape which is compatible with (e.g. fit within) the barrel of a gun from which is it being fired. That is to say, the driving band 100 may be of any appropriate shape.

[0054] In the example shown in the figures, the driving band 100 may be cylindrical i.e. a hollow tube with circular ends. The driving band 100 may be provided as a ring extending between a first edge 110 of the driving band 100 to a second edge 120 of the driving band 100, the first edge 110 and second edge 120 being spaced apart from one another along an axial / longitudinal direction. The driving band 100 may comprise a radially inner surface 102 which defines a first engagement feature 104 for engagement with a second engagement feature 204 on a main body 202 of an artillery shell 200 (as shown in figures 6 to 11).

[0055] The driving band 100 may be formed by any suitable method. The driving band 100 may be formed using a powder metallurgy process, which may comprise a hot isostatic pressing process. For example, the driving band 100 may be formed from a custom alloy which is mixed and pressed (e.g. using hot isostatic pressing) before sintering to form a billet, which can then be parted off in the sizes required.

[0056] The shape memory alloy used to form the driving band 100 (and hence the driving band 100 itself) may be configured to enable (e.g. have a composition which enables) the driving band 100 to expand from a first diameter D1 to a second diameter D2 when raised from a first temperature T1 to a second temperature T2, as illustrated in figures 7, 8. The second temperature T2 may be higher than the first temperature T1. The first diameter D1 may be less than the second diameter D2. The term "diameter" may refer to inner diameter, or outer diameter. In the context of the driving band 100 being fitted to an artillery shell 200, the terms first diameter D1 and second diameter D2 may be taken to refer to the inner diameter of the driving band 100 (i.e. the diameter which interfaces with the outer surface of the shell 200.

[0057] Hence the shape memory alloy may have a composition which enables it to thermally expand from a first diameter D1 to a second diameter D2 when raised from a first temperature T1 to a second temperature T2 , for example as illustrated in figure 7 (in which the driving band 100 is at the first temperature T1 and has a first diameter D1) and figure 8 (in which the driving band 100 is at the second temperature T2 and has a second diameter D2).

[0058] The shape memory alloy used to form the driving band 100 (and hence the driving band 100 itself) may be configured (e.g. have a composition which enables it) to contract from the second diameter D2 to the first diameter D1 when lowered from the second temperature T2 to the first temperature T1, for example as illustrated in figure 9 (in which the driving band 100 is at the second temperature T2 and has a second diameter D2) and figure 10 (in which the driving band 100 is at the first temperature T1 and has a first diameter D1). Hence the shape memory alloy used to form the driving band 100 (and hence the driving band 100 itself) may be configured (e.g. have a composition which enables it) to be shrunk onto (and hence engage with and / or be fixed relative to) a feature of a shell 200 which defines an outer surface of the shell 200 for example as illustrated in figures 9, 10 such that the driving band 100 grips the shell casing (e.g. the outer surface of the shell 200).

[0059] The driving band 100 may have a material composition such that the material / mechanical properties of the shape memory alloy (and hence the driving band 100) are a function of the temperature of the shape memory alloy (and hence the driving band 100). The material properties (e.g. mechanical properties) may comprise strength, ductility and / or erosion resistance.

[0060] At the first temperature T1, when at the first diameter D1, and prior to being raised to the second temperature T2 (to have the second diameter D2), the shape memory alloy has a first set of material properties. After being lowered from the second temperature T2 to the first temperature T1 (and hence contracting from the second diameter D2 to the first diameter D1), the driving band 100 has the first set of material properties.

[0061] Hence a material composition is chosen such that the material properties of the material of the driving band 100 is the same before and after heating, cooling, expansion and contraction. That is to say, the shape memory alloy of the present disclosure returns to its original properties after being heated and expanded (i.e. when it has cooled and contracted).

[0062] This may, for example, be due to reversible phase transformation between martensite and austenite of a shape memory alloy. When heated, the shape memory alloy may transform from the martensitic phase to the austenitic phase. When then cooled, it may revert back to the martensitic phase, and so the material properties of the material of the driving band 100 (and hence the driving band 100) may also revert to their original state after the heating and cooling cycle. Hence the driving band 100 is configured to undergo a reversible transformation which allows it to consistently return to its pre-deformed shape and properties.

[0063] Hence in the fitting of the driving band 100 to the shell 200 (as will be described) the material / mechanical properties of the driving band 100 when fitted to the shell 200 are known, since they will be the same as the material / mechanical properties of the driving band 100 prior to being fitted to the shell 200, which may be empirically determined by any suitable conventional means.

[0064] The shape memory alloy may comprise copper as this provides ductility and thermal conductivity.

[0065] The shape memory alloy (and hence the driving band 100) may comprise a decoppering agent. The decoppering agent may vaporize or liquefy upon ignition of the propellant used to fire the shell, which helps to embrittle or dissolve any copper deposits formed on the internal features of the gun barrel (e.g. rifling), which facilitates removal of the copper, hence maintaining the efficacy of the gun barrel features (e.g. to keep the weapon accurate) and reduce wear.

[0066] The decoppering agent may be tin, bismuth or antinomy.

[0067] The decoppering agent may form part of the composition of the shape memory alloy (e.g. be an integral component). For example the decoppering agent may be mixed into the shape memory alloy prior to pressing and densification (e.g. in a hot isostatic pressing process). Alternatively, the decoppering agent may be provided as a layer on the radially outer surface of the driving band 100, for example by physical or chemical vapour deposition.

[0068] The shape memory alloy may comprise copper, nickel, iron, graphite and tin.

[0069] The shape memory alloy may comprise 50-60% copper, 15-20% nickel, 5-10% iron, 0.5-1.5% graphite and 1-3% tin. No more than 1% shape memory alloy may be comprised of a wax binder.

[0070] The nickel may add strength as well as heat and wear resistance. Iron may improve mechanical strength and hardness, and act as a lubricator to reduce barrel wear.

[0071] The graphite may enhance corrosion resistance and improve ductility of the material. The graphite may also provide barrel lubrication, which may prevent adhesion of material of the driving band (e.g. copper) from the driving band to the barrel of the gun as it moves along the gun barrel. Any material deposited in the barrel of the gun may then be blown out, for example by decoppering agents in the propellant.

[0072] The tin may provide corrosion protection, and may also contribute to reduced copper build up by forming low melting intermetallic compounds with copper. This will reduce adhesion to the barrel.

[0073] The wax binder may be provided as a processing agent that will evaporate during sintering.

[0074] As illustrated in figure 11, there may be provided a shell 200 for an artillery weapon (e.g. an artillery weapon with a gun barrel). The shell 200 may comprise a main body 202 which defines, and extends along, a longitudinal axis 208 from a leading edge end 220 to a trailing edge end 222.

[0075] Figures 6 to 11 show sectional views of components of a shell 200 during stages in the assembly of the shell 200. Figure 5 shows a side view of the main body 202 of the shell 200. Figure 6 shows a sectional view of the main body 202 of the shell 200. Figure 11 shows a sectional view of an assembled artillery shell 200.

[0076] The main body 202 may define at least part of a recess 240 which extends around the circumference of the main body 202. The driving band 100 may be located in the recess 240 (for example, as shown in figures 10, 11).

[0077] Hence there may be provided a shell assembly 200 comprising a driving band 100 according to the present disclosure which extends around the circumference of the main body 202 of a shell 200 at a location between the leading edge end 220 and the trailing edge end 222 of the main body 202.

[0078] As illustrated in figures 10, 11, the shell 200 may comprise a tail unit 300 which is fitted to the trailing edge end 222 of the shell 200. The tail unit 300 may comprise a chamber for propellant and / or features for stabilising the shell assembly 200 when in flight. Alternatively, or additionally the tail unit 300 may form a trailing end cap of the shell assembly, for example to reinforce the trailing edge end 222 of the main body 202.

[0079] The trailing edge end 222 of the main body 202 of the shell 200 may define a first coupling feature 230. The tail unit 300 may define a second coupling feature 330. The first coupling feature 230 and the second coupling feature 330 may be configured to couple the main body 202 and the tail unit 300 to one another. The first coupling feature 230 and the second coupling feature 330 may be provided with any suitable configuration.

[0080] In the example shown in figures 5 to 11 the first coupling feature 230 of the main body 202 defines a male extension 250 (e.g. for example comprising one or more stepped lands 232, 234 which define a radially outer diameter of the male extension 250). In the example shown in figures 10, 11 the second coupling feature 330 of the tail unit 300 defines a female connector 350 (e.g. comprising one or more stepped lands 332, 334 which define a radially inner diameter of the female connector 350). Hence the female connector 350 of the tail unit 300 may be provided as a cavity with an opening for receiving the male extension 250 of the main body 202. One or more of the main body lands 232, 234 or the tail unit lands 332, 334 may be threaded such that the parts may be screwed together to thereby couple the main body 202 to the tail unit 300.

[0081] In the assembled shell 200 of the present disclosure, the recess 240 is defined by, and extends between, a first location feature 242 provided on the main body 202 of the shell 200 and a second location feature 342 provided on the tail unit 300.

[0082] As illustrated in figure 5, the recess 240 is in part formed by the main body 202. The first location feature 242 may be an edge wall defined by a first step 244 (e.g. a reduction in radius) from the radially outer surface 212 of the main body 202 to a base wall 246 of the recess 240, the base wall 246 extending in an axial direction from the first step 244 in a direction towards the trailing edge end 222. Hence the base wall 246 of the recess 240 may extend from the bottom (i.e. radially inner location) of the first step 244 in a direction parallel to the longitudinal axis 208, and terminates at a second step 248 (e.g. a reduction in radius) which extends down to the adjacent lands 232, 234 of the male extension 250.

[0083] As illustrated in figure 10, the second location feature 342 may be provided by an outer region and / or end region of the tail unit 300 which extends around, and defines the opening to, the female connector 350. Hence when the tail unit 300 is fitted to the main body 202, the second location feature 342 abuts the second step 248 and extends radially outwards beyond the radius of the base wall 246 such that the second location feature 342 defines a side wall of the recess 240. Hence the first step 244 defines a first side wall of the recess 240 and the second location feature 342 defines a second side wall of the recess 240, the first side wall being spaced apart from the second side wall by the base wall 246.

[0084] As shown in the figures, the recess 240, and the land (or lands) 232, 234 may be provided in series along the length of the main body 202 in the direction from the leading edge end 220 to the trailing edge end 222, such that the recess 240 is spaced apart from the trailing edge end 222 by the land (or lands) 232, 234.

[0085] Hence the recess 240 is formed between the first step 244 on the main body 202 and the end wall (e.g. the second location feature 342) of the tail unit 300.

[0086] The outer diameter of the recess 240 is greater than the outer diameter of the or each of the lands 232, 234.

[0087] The lands 232, 234 in the series of lands may have a different outer diameter to one another. The outer diameter of each subsequent land 232, 234 in the series may be less than the land which precedes it in the series such that the male extension 250 reduces in diameter along its length in the direction from the leading edge end 220 to the trailing edge end 222.

[0088] The lands 332, 334 in the series of lands of the tail unit 300 may have a different inner diameter to one another. The inner diameter of each subsequent land 332, 334 in the series is less than the land which precedes it in the series such that the female connector 350 tapers (i.e. reduce in diameter) from its opening.

[0089] The profile of the male extension 250 and the female connecter 350 may be configured such that they mate together.

[0090] The driving band 100 and recess 240 are configured such that the driving band 100 may be located by the first location feature 242 and the second location feature 342 within the recess 240. For example, and as shown in the figures, when in situ, the driving band 100 may abut the first location feature 242 and the second location feature 342.

[0091] A second engagement feature 204 may be provided in the recess 240, the second engagement feature 204 may be provided as a protrusion 210 which extends radially away from the main body 202 and in an axial direction along the longitudinal axis 208, and configured for engagement with the first engagement feature 104. Hence the second engagement feature 204 (e.g. protrusion 210) may be formed integrally with the main body 202.

[0092] In an alternative example, and as shown in the figures, the second engagement feature 204 may be provided as a member / element which protrudes from the main body 202. The second engagement feature 204 may be provided as a key 400. For example (and as shown in the figures), the key 400 may be provided as a mechanical component / element, separately formed to the driving band 100 and shell body 202.

[0093] The second engagement feature 204 (e.g. protrusion 210, key 400) may be configured to extend between, and engage with both, the driving band 100 and the main body 202 to thereby prevent relative rotation between the driving band 100 and the main body 202. That is to say, the second engagement feature 204 (e.g. protrusion 210, key 400) prevents relative rotation between the driving band 100 and the main body 202, ensuring they move together as a single unit. This effectively locks the parts together, allowing torque induced on the shell as it travels along a gun barrel to be transmitted (e.g. through the driving band 100 to the shell 200) without slippage.

[0094] As shown in figure 3, 4, the first engagement feature 104 of the driving band 100 may be provided as a channel 106 which extends in an axial direction from the first edge 110 of the driving band 100 to the second edge 120 of the driving band 100. The channel / slot 106 may be provided in the radially inner surface 102 of the driving band 100.

[0095] There may be provided a channel / slot 206 in the recess 240, configured for the key 400 to fit within. The second engagement feature 204 (e.g. protrusion 210 or key 400) may extend radially away from the main body 202 and also extend in an axial direction along the longitudinal axis 208.

[0096] Both the channel / slot 106 in the radially inner surface 102 of the driving band 100 and the channel / slot 206 in the recess 240 of the main body 202 of the shell 200 may be aligned (e.g. extend in the same direction along the longitudinal axis 208).

[0097] Hence the first engagement feature 104 (e.g. channel 106) and the second engagement feature 204 (e.g. protrusion 210 or key 400) may be configured to allow the driving band 100 to slide relative to the shell 200 along the longitudinal axis 208 and prevent relative rotation of the driving band 100 and shell 200 around the longitudinal axis 208.

[0098] There may be provided one or more first engagement features 104 (e.g. channels 106). In examples in which there are provided a plurality of first engagement features 104, they may be spaced apart from one another around the radially inner surface 102 of the driving band 100.

[0099] There may be provided one or more second engagement features 204 (e.g. protrusion 210 or key 400 with an associated channel / slot 206 in the recess 240). In examples in which there are provided a plurality of second engagement features 204, they may be spaced apart around the recess 240.

[0100] The number of first engagement features 104 may equal the number of second engagement features 204.

[0101] There may be provided a method of assembly of a shell 200 for an artillery weapon.

[0102] As illustrated in figures 7, 8 the method may comprise the step of controlling the temperature of the driving band 100 so that it is at a temperature greater than the main body 202 such that the driving band 100 increases in diameter from a first diameter D1 (as shown in figure 7) to a second diameter D2 (as shown in figure 8). The method may comprise the step of heating the driving band 100 so that it is at a temperature greater than the main body 202. For example, the method may comprise the step of heating the driving band 100 so that it is at a temperature greater than the main body 202 such that the driving band 100 increases in diameter from a first radially inner diameter D1 to a second radially inner diameter D2.

[0103] As illustrated in figures 8, 9, the method may comprise the step of sliding the driving band 100 onto the main body 202 while it is at the second temperature T2 (e.g. hotter than the first temperature T1 and having a diameter greater than D1). The driving band 100 may be pressed into position on the main body 202.

[0104] As illustrated in figure 9, the method may comprise the step of locating the driving band 100 in / on the recess 240 while it is at the second temperature T2 (e.g. hotter than the first temperature T1 and having a diameter greater than D1). The driving band 100 may be pressed into position in the recess 240.

[0105] That is to say, the driving band 100 may heated until its diameter is large enough to allow it to be slid onto the main body 202 and located in / on the recess 240 (e.g. onto the base wall 246 and abut the first location feature 242 (e.g. the first step 244)). Hence the method may comprise locating the driving band 100 such that it abuts the first location feature 242.

[0106] As will be appreciated, the figures may show the second diameter D2 to be exaggerated relative to the first diameter D1. That is to say, it will be appreciated that the increase in diameter from D1 to D2 may not be to the same degree as illustrated in the figures.

[0107] As illustrated in figures 9, 10, the method may comprise the step of, once the driving band 100 is located in the recess 240, controlling the temperature of the driving band 100 so that it is at the same temperature as the main body 202 such that the driving band 100 decreases in diameter from the second diameter D2 to the first diameter D1 to engage with (e.g. grip onto) the main body 202.

[0108] Hence the first diameter D1 may be the same as the diameter of the recess 240 (e.g. the diameter of the base wall 246 of the recess 240) such that when the driving band 100 contracts during a reduction in temperature from the second temperature T2 (as shown in figure 9) to the first temperature T1 (as shown in figure 10) the driving band 100 clamps down onto the surface of the main body 202 that defines the recess 240 (i.e. the base wall 246). The first diameter D1 of the driving band 100 may be slightly less than the diameter of the recess base wall 246 (i.e. the recess 240) such when the driving band 100 contracts during the reduction in temperature from the second temperature T2 to the first temperature T1, the driving band 100 clamps down onto, and slightly compresses, the surface of the recess 240 (i.e. the base wall 246).

[0109] The method may comprise coupling the main body 202 and tail unit 300 to one another by coupling the first coupling feature 230 and the second coupling feature 330, such that the recess 240 is defined by, and extends between, the first location feature 242 provided on the main body 202 and the second location feature 342 provided on the tail unit 300. The first coupling feature 230 and the second coupling feature 330 may be threaded with compatible threads such that the tail unit 300 may be fixedly attached to main body 202. Hence the tail unit 300 may effectively act as a retaining feature for the driving band 100, in addition to the key 400 and the driving band's 100 fit to the main body 202 by compressive contraction, clamping it to the main body 202.

[0110] The method may comprise coupling the main body 202 and tail unit 300 to one another by coupling the first coupling feature 230 and the second coupling feature 330, such that the driving band 100 abuts the first location feature 242 on the main body 202 and the second location feature 342 on the tail unit 300.

[0111] The method may comprise coupling the male extension 250 and the female connector 350 such that the driving band 100 abuts the first location feature 242 and the second location feature 342.

[0112] The method may comprise providing the second engagement feature 204 (e.g. protrusion 210, key 400) in the recess 240 before the driving band 100 is located in the recess 240 (e.g. as shown in figures 6, 7) and then sliding the driving band 100 onto the main body 202 to engage the first engagement feature 104 (e.g. channel 106) and the second engagement feature 204 (e.g. protrusion 210, key 400) (as shown in figures 8, 9) so as to prevent relative rotation of the driving band 100 and shell 200 around the longitudinal axis 208.

[0113] The method may comprise providing the key 400 in the recess 240 (e.g. the channel / slot 206 in the recess 240) (e.g. as shown in figures 6, 7) before the driving band 100 is located in the recess 240 and then sliding the driving band 100 onto the main body 202 to engage the channel 106 and the second engagement feature 204 (e.g. protrusion 210, key 400) (as shown in figures 8, 9) so as to prevent relative rotation of the driving band 100 and the main body 202 around the longitudinal axis 208.

[0114] Hence the driving band 100 may be heated up (for example by an induction heater) and slid and / or pressed into position on the main body 202 before being cooled to be clamped to the main body 202.

[0115] There may be provided a method for dis-assembling the tail unit 300 by removing the tail unit 300 from the main body 202 (for example by unscrewing it) and then heating the driving band 100 such that it expands and may be slid and / or pulled from the recess 240 and removed from the main body 202.

[0116] Hence there may be provided a driving band with material / mechanical properties which are unchanged by being fitted to an artillery shell assembly.

[0117] The choice of material of the driving band (e.g. shape memory alloy) enables the driving band to have the same material properties before and after it is fitted to the artillery shell. This enables modelling of the interactions between the driving band and the gun barrel to be more accurate than with materials and processes of the related art, thereby making their performance easier to predict, and hence reducing the need for lengthy and expensive physical testing, thereby aiding research and development, and / or reducing cost, for the development of driving bands and / or weapon shells.

[0118] The fitting process enabled by the material of the driving band does not cause issues which are present with materials of the related art. For example, the choice of material avoids issues such as work hardening (which may increase the hardness and of the driving band and also make it more brittle), thermal effects (e.g. altering its microstructure which might alter its strength and wear resistance), material deformation (which may lead to wear and potential failure if the material is not sufficiently resilient).

[0119] Additionally, the features of the driving band 100 (e.g. being made from a shape memory alloy) and / or the shell 200 (e.g. provision of the recess 240 defined by the main body 202 and the tail unit 300 to locate the driving band 100) enable the driving band 100 to be fitted to and removed from a shell 200, and in some examples, reused on the same or another shell. Hence if during the manufacture of a shell it is determined that the driving band has not been fitted correctly, or is in some way damaged, it may be removed from the shell assembly and replaced. Alternatively, if the shell body has been damaged then the driving band may be removed from the shell and used on a different shell body. This is made possible by the use of a shape memory alloy, which allows for the driving band to be expanded and contracted a number of times with little or no change in material properties. This capability means that there is opportunity for material that would otherwise be wasted in the manufacturing and assembly process to be reused with little or no adaption.

[0120] The composition of the material of the driving band may also be advantageous to maintain the effectiveness of the gun barrel for which is being fired, for example by reducing the amount of metal (e.g. copper) deposited on the inner surfaces of the gun barrel. Restricting the decoppering agent to just the driving band (rather than covering the whole shell as may be done in other fields, such as in small calibre round in a handgun) means that a large cost and complication (and associated cost) of applying a decoppering agent to a large section of the shell may be avoided.

[0121] The provision of engagement features between the driving band and the artillery shell to prevent rotational movement of the driving band relative to the artillery shell, which thereby reduces possible wear on the main body of the shell, ensures rotation is imparted to the shell by the rifling, increasing the accuracy of the shell.

[0122] Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[0123] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive.

[0124] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0125] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A driving band comprising a shape memory alloy material.

2. A driving band as claimed in claim 1 wherein: the shape memory alloy is configured to expand from a first diameter (D1) to a second diameter (D2) when raised from a first temperature (T1) to a second temperature (T2); and the shape memory alloy is configured to contract from the second diameter (D2) to the first diameter (D1) when lowered from the second temperature (T2) to the first temperature (T1).

3. A driving band as claimed in claim 2 having a material composition such that the material properties of the shape memory alloy are a function of the temperature of the shape memory alloy, such that: at the first temperature (T1), prior to being raised to the second temperature (T2), the shape memory alloy has a first set of material properties; and after being lowered from the second temperature (T2) to the first temperature (T1), the driving band has the first set of material properties.

4. A driving band as claimed in any one of claims 1 to 3 wherein the shape memory alloy comprises a decoppering agent.

5. A driving band as claimed in any one of claims 1 to 4 wherein the shape memory alloy comprises copper, nickel, iron, graphite and tin.

6. A driving band as claimed in claim 5 wherein the shape memory alloy comprises 50-60% copper, 15-20% nickel, 5-10% iron, 0.5-1.5% graphite and 1-3% tin.

7. A driving band as claimed in any one of claims 1 to 6 wherein no more than 1% shape memory alloy is comprised of a wax binder.

8. A driving band as claimed in any one of claims 1 to 7 further comprising a radially inner surface which defines a first engagement feature for engagement with a second engagement feature on a main body of an artillery shell; the first engagement feature and the second engagement feature configured to couple to one another so as to: allow the driving band to slide relative to the shell along its longitudinal axis; and prevent relative rotation of the driving band and shell around the longitudinal axis.

9. A driving band as claimed in claim 8 wherein the first engagement feature is provided as a channel which extends in an axial direction from a first edge of the driving band to a second edge of the driving band.

10. A driving band as claimed in any one of claims 1 to 9 wherein the driving band is formed using a powder metallurgy process.

11. A shell for an artillery weapon comprising: a main body which defines, and extends along, a longitudinal axis from a leading edge end to a trailing edge end; a driving band as claimed in any one of claims 1 to 10 which extends around the circumference of the main body at a location between the leading edge end and the trailing edge end.

12. A shell as claimed in claim 11 wherein the main body defines a recess which extends around the circumference of the main body; and the driving band is located in the recess.

13. A shell as claimed in claim 12 when dependent on claim 8 or claim 9 wherein: the second engagement feature is provided in the recess, the second engagement feature being provided as a protrusion which extends radially away from the main body and in an axial direction along the longitudinal axis, and configured for engagement with the first engagement feature of the driving band, the first engagement feature and the second engagement feature configured to: allow the driving band to slide relative to the shell along the longitudinal axis; and prevent relative rotation of the driving band and the shell around the longitudinal axis.

14. A shell as claimed in claim 12 or claim 13 wherein: the trailing edge end of the main body defines a first coupling feature; the shell comprises a tail unit; and the tail unit defines a second coupling feature; the first coupling feature and the second coupling feature being configured to couple the main body and the tail unit to one another; the recess is defined by, and extends between, a first location feature provided on the main body and a second location feature provided on the tail unit; and the driving band abuts the first location feature and the second location feature.

15. A method of assembly of a shell for an artillery weapon, the shell comprising: a main body which defines, and extends along, a longitudinal axis from a leading edge end to a trailing edge end; and the main body defines a recess which extends around the circumference of the main body; a driving band configured to extend around the circumference of the main body between the leading edge end and the trailing edge end; the method comprising: controlling the temperature of the driving band so that it is at a temperature greater than the main body such that the driving band increases in diameter; sliding the driving band onto the main body; locating the driving band in the recess; and controlling the temperature of the driving band so that it is at the same temperature as the main body such that the driving band decreases in diameter to engage with the main body.

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