Dart flight

Abstract

A dart flight (100) has multiple wings (110) and a front end arranged to be inserted into the rear end of a dart flight stem (200) having elongate petals (210) arranged to grip the wings (110) of the

Description

Technical Field The present invention relates to darts, specifically those used in the popular game that involves throwing darts at a target dart board, and more particularly to flights for darts and methods of manufacturing these. Background The game of darts is well known and has existed in one form or another for centuries. It is a highly popular international sport and is televised around the World. The modern version of darts is played by two players taking turns to throw three darts in sequence into a dart board. The front face of the dart board describes a circular scoring zone that is divided into twenty numbered segments around a central bullseye. Points are awarded to each player corresponding to the number of the segment into which each of their thrown darts sticks. Each segment is sub-divided into bands, with a central band awarding triple points and an outermost band awarding double points. Adjacent segments of the board are painted in alternating colours, typically black and white. The adjacent segments and bands are also physically separated from one another by a frame of wire that runs along each boundary therebetween on the front face of the dart board. Each dart is constructed with a point (or tip), a barrel, a stem (or shaft), and a flight. The point is arranged to project forward from the barrel at the front of the dart and is designed to impact and stick into the dart board. The barrel is a substantially cylindrical body typically extending about half to two-thirds of the length of the dart. 26 09 25 The stem extends backwards from the barrel and carries the flight at the back of the dart, which serves to stabilise the dart in flight when thrown. Typically, the stem is made of lighter-weight material than the barrel and is threaded at its front end so that it can be screwed into the back end of the barrel to assemble the dart. The threaded connection allows the stem to be unscrewed and detached from the barrel, for example to disassemble the dart for storage in a case or for replacement in the event of the stem breaking. In order to score highly and efficiently, darts players typically attempt to group their three darts as closely as possible on the dart board. If the first dart is well placed, it can act as a guide for subsequent darts, with the flight, stem and barrel of the first dart helping to guide the tip of the next incoming dart into position adjacent the tip of the first dart. The point and barrel of a dart are made of resilient materials. The barrel is typically made from a tungsten alloy to provide the dart with a front-loaded mass distribution with minimum barrel diameter, so as to promote stable flight and permit close grouping of thrown darts. By contrast, the stem is normally made of a lighter-weight polymer material such as nylon or polycarbonate. While the front end of the stem is provided with a thread for connection to the barrel, the back end of the stem is formed with four elongate petals defining a cross-slit between them (when viewed from the rear of the stem) for receiving the flight in the slits and thereby gripping the flight between the petals. During a game of darts, the flights can fall out of the dart shaft when the dart impacts the board, typically when the dart hits another dart already in the board. 26 09 25 This prevents the player from relying on the flight of the dart in the board as a guide for their successive darts. It can also interrupt a player's concentration and disturb game play as the player attempts to re-insert the flights back into the dart shaft. To mitigate this problem, players sometimes use a shaft ring that goes over the petals and sits just in front of the flight. The ring has a fixed diameter, while the petals are tapered along their axial length, so that forcing the ring axially along the petals urges the petals together, thereby squeezing the flight to increase the friction force between the flight and the petals. However, one disadvantage of shaft rings is that they protrude radially from the shaft, with the consequence that subsequent darts can be deflected away from the desired scoring zone if the incoming point strikes the shaft ring. Summary of the Present Invention The present invention has been made in view of the realisation and recognition by the inventors of the aforementioned problems which may arise in prior art designs. The present invention seeks to alleviate or solve one or more of these problems. According to a first aspect of the present invention, there is provided a dart flight having multiple wings and having a front end arranged to be inserted into the rear end of a dart flight stem having elongate petals arranged to grip the wings of the flight between the petals, wherein at least a portion of the surface of one or more of the wings inside and / or outside the area to be gripped by the petals is provided with a coating, and wherein the coating is textured. 26 09 25 According to a second aspect of the present invention, there is provided a method of manufacturing a dart flight comprising: providing a web of flight material; selectively applying a coating material to all or part of one side of the web, wherein the applied coating material forms a textured coating; and cutting and / or folding the web of flight material to form the wings of the dart flight. Optional and preferred features are mentioned in the detailed description below and recited in the dependent claims. Brief Description of the Drawings To enable a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:- Figure 1 shows a perspective view from the rear of the front end of a dart flight according to the present invention proximate the rear end of a dart flight stem into which it can be inserted; Figure 2 shows a perspective view from the front of the dart flight of Figure 1 inserted into the rear end of the dart flight stem of Figure 1; Figure 3 shows a schematic view of an apparatus and method for use in manufacturing dart flights in accordance with the present invention; and Figures 4A and 4B show embodiments of dart flight wings with alternative coating patterns. Detailed Description 26 09 25 The invention will now be described with reference to specific embodiments. It is to be understood that the disclosed embodiments are provided in order to demonstrate one or more ways of putting the invention into effect and that they are in no way to be considered as being limiting on the scope of protection, which is defined solely by the appended claims. Throughout the figures, like reference numerals are used to refer to like components. Figure 1 shows a perspective view from the rear of an embodiment of a dart flight 100 according to the present invention. The dart flight 100 is shown in a perspective view from the rear, with a front end of the dart flight 100 proximate and adjacent to the rear end of a dart flight stem 220, prior to insertion of the dart flight 100 into the cross slit 220 between the axially rearwardly extending petals 210 of the dart flight stem 200. The dart flight 100 includes four wings 110, arranged at 90 degrees to one another in a cross-shape when viewed front-to-back along a longitudinal axis of the dart flight 100. The wings 110 are thus arranged to be inserted into the cross slit 220 formed between the four adjacent axially extending petals 210 at the rear end of the dart flight stem 200. Three of the dart flight wings 110 are visible in Figure 1. At the front end of the dart flight 100, there is a portion which is to be inserted into the cross slit 220 between the elongate petals 210 of the dart flight stem 200, so as to be gripped by the adjacent elongate petals 210 in order to hold the dart flight 100 in place at the rear end of the dart flight stem 200. Each of the wings 110 is grasped or clamped between the two adjacent elongate petals 210 when inserted in the cross slit 220. 26 09 25 Figure 2 shows the dart flight 100 inserted into the cross slit 220 at the rear end of the dart flight stem 200, with each of the wings 110 located between an adjacent pair of elongate petals 210. It can be seen that the dart flight 100 includes a portion or region of each wing 110 which is the area gripped by the respective petal 210. As shown in Figure 2, the dart flight stem 200 also includes a shaft ring 230. Although one of the intended advantages of the present invention is to obviate the need for a shaft ring in order to secure the dart flight 100 to the dart flight stem 200, the use of a shaft ring 230 is nevertheless not excluded. As most clearly visible in Figure 1, each of the wings 110 of the dart flight 100 is provided with a series of lines or stripes 120 of a coating material in the region of each wing corresponding to the area to be gripped by the dart flight stem petals 210. A further, substantially triangular area 130 is also provided, visible in between the lines or stripes 120 of the coating material, extending along the axial length of the region to be gripped of each wing 110. The area 130 may also be coated with a coating material, if desired. Such a coating may be applied across the whole of triangular area 130 or only between the lines or stripes 120. Any coating material used in the region 130 may be the same coating material as used for the lines or stripes 120, or the coating material used in area 130 may have a different formulation. For example, inter alia, the coating material used in area 130 may be made of a different material or may have a different average surface roughness, Ra. In the embodiment of Figures 1 and 2, the remainder of the wings 110 outside the areas 120 and / or 130 are uncoated, and are formed from a sheet or film of polyester, typically of 75 pm to 150 pm in thickness. The coating material of lines or stripes 120 is applied to the surface of the dart flight wings 110 in order to improve the grip between the elongate petals 210 of the dart flight stem 200 and the wings 110 of the dart flight 100. To this end, the coating may be considered a friction enhancing coating, having a greater coefficient of friction with the material of the petals 210 of the dart flight stem 200 than the coefficient of friction existing between the uncoated material of the dart flight wings 110 and the material of the elongate petals 210 of the dart flight stem 200. The frictional interaction between the dart flight 100 and the dart flight stem 200 may be improved, in one way, simply by judicious selection of the coating material, i.e., by selecting a high friction material. 26 09 25 More preferably, the coating material is a so-called textured coating material, which when applied to the surface of the dart flight wings 110 will produce a friction enhancing microstructure at the outer surface of the coating. To this end, a textured coating is understood to be one having a micrometre scale macrostructure at the outer surface of the coating. For example, the macrostructure may exhibit an average surface roughness, Ra, from 1 pm to 100 pm. Such a textured surface may also be referred to as a haptic or tactile surface, as the surface roughness can normally be felt and detected by touch by a human finger. Suitable textured coatings are known and available from a number of different companies, including PPG Industies UK, Ltd (PO Box 162, Needham Road, Stowmarket, Suffolk, IP14 2ZR, United Kingdom), Sun Chemical Group GmbH (Borsigallee 13, 60388 Frankfurt, Germany), Weilburger Coatings GmbH (Ahauser Weg 12-22, 35781 Weilburg, Germany), and INX International Ink Co (150 North Martingale Road, Suite 700, Schaumburg, IL 60173, USA) . Examples of suitable such coating materials are known from US Patent 6,730,388 B2 to MacQueen et al. Particular reference is made to the disclosure at column 9, lines 15 to 62. The entire contents of this document are hereby incorporated herein by reference in their entirety. 26 09 25 The preferred coatings comprise a transparent UV-curable coating, preferably a varnish or ink. Thermally-activated or cured varnishes or inks would also be feasible. The varnish or ink is loaded with texture particles having an average diameter that is larger than the pre-cured film thickness. This results in the particles creating a surface roughness on the outside of the film after curing. The texture particles have a D(4,3) weighted mean diameter by volume of from 1 pm to 150 pm, preferably from 10 pm to 100 pm, and most preferably from 30 pm to 80 pm. To ensure that the particles will produce a textured or roughened outer surface when the coating has cured, the ratio of the D(4,3) weighted mean diameter by volume of the texture particles to the average thickness of the coating before curing is greater than 1. The choice of texture particles is not particularly limited providing that they produce a desirable roughened surface on the outside of the coating with an enhanced frictional interaction with the elongate petals 210 of the dart flight stem 200. Nonetheless, preferred inorganic texture particles include particles of glass, ceramic, alumina, silica, aluminosilicates, and / or alumina coated on silica. Similarly, preferred organic particles include those of polyamide, nylon, polypropylene, polyethylene, polytetrafluoroethylene, ethylene copolymers, waxes, epoxy, and / or urea-formaldehyde. Nylons specifically include nylon 6 and nylon 12, although other nylons are also included. The coating material typically contains from 1% to 30% by weight of such texture particles, and more preferably from 5% to 15% by weight of the texture particles. This ensures a good distribution of the texture particles across the coated surface, whilst securely bonding the texture particles onto the surface being coated. As well as improving the frictional contact between the elongate petals 210 of the dart flight stem 200 and the wings 110 of the dart flight 100, the coating material may also have additional effects on the performance of the dart flight. For example, the provision of the coating material may enhance the stiffness and rigidity of the dart flight wings 110 in the coated region. 26 09 25 Furthermore, the textured surface of the coating material may also alter the airflow properties over the wings 110 of the dart flight 100. As will be appreciated, an object moving through the air leaves behind a turbulent wake region where the airflow is fluctuating or agitated, resulting in lower pressure behind the object. The size of the wake affects the amount of drag on the object. By providing a textured surface on the wings 110 of the dart flight 100, it is possible to create a thin turbulent boundary layer of air that clings tightly to the surface of the wings 110 of the dart flight 100. This reduces the size of the wake and allows the air to flow more smoothly over the surface of the dart flight, compared to an untextured surface. This effect is enhanced if the dart is rotating through flight. A dart flight provided with a textured coating may thus have a reduced drag coefficient compared to a dart flight having an untextured surface. This may be preferable for some darts players. To this end, the textured coating may be applied to the surface of the dart flight wings 110 not only in the region contacted by the elongate petals 210 of the dart flight stem 200, but also extending onto the main surfaces of the dart flight wings 110. This can be seen most clearly in Figure 2 of the present application in which the lines or stripes 120 of the coating material extend beyond the region gripped by the elongate petals 210 of the dart flight stem 200. 26 09 25 The choice of pattern for the application of the textured coating is not particularly limited, and may be adjusted according to need or preference. As shown in Figure 1 of the present application, lines or stripes 120 of the coating material are provided in the present embodiment, and these may be provided as straight lines or in a chevron pattern. The coating may equivalently or alternatively be provided as curved lines or stripes, or as a series of dots. Example coating patterns are shown in Figures 4A and 4B for embodiments of coated flight wings 110A and HOB respectively. In Figure 4A, substantially the entire surface of the flight wing 110A is covered. In Figure 4B, straight lines or stripes 120B are provided across the wing HOB in the region of the flight wing HOB contacted by the elongate petals 210 of the dart flight stem 200, while axially extending curved lines or stripes 140B of coating material are provided across the remainder of the surface of the wing HOB. Turning to Figure 3, there is shown a schematic representation of an example method and apparatus 300 for applying the coating material onto the surface of the dart flight 100. The dart flight material is provided as a substrate or web 310, typically of polyester. The polyester web preferably has a thickness from 75 pm to 150 pm, more preferably of 80 pm to 120 pm, most preferably of about 100 pm. In order to apply the coating material onto the surface of the substrate 310, a flexographic plate 320 is provided, mounted on a plate cylinder 325, in order to print a controlled quantity of the coating material onto the substrate surface by way of a rolling contact with the substrate 310 against an impression cylinder 315. 26 09 25 In order to deliver a controlled quantity of the coating material to the flexographic plate 320, an anilox roller 330 may be used. Such an anilox roller 330 has discrete cells 335, provided in the desired shape of the printed coating pattern, for carrying a controlled quantity of the coating material on an outer surface of the anilox roller 330. Rolling contact between the anilox roller 330 and the flexographic plate 320 transfers the coating material from the cells 335 of the anilox roller 330 to the flexographic plate 320. In order to load the coating material into the cells 335 of the anilox roller 330, a fountain roller 340 is provided, which carries the coating material, namely a resin or ink as described above, from an ink tray 345 to the outer surface of the anilox roller 330. An excess of the coating material is provided to the anilox roller 330 to ensure that the cells 335 are filled with the desired quantity of coating material. A doctor blade 350 is provided to remove any excess coating material from the outer surface of the anilox roller 330, before it comes in contact with the flexographic plate 320 mounted to the plate cylinder 325. The use of a fountain roller 340 and ink tray 345 ensures that the coating material can remain in a well-mixed condition, without settling of the texture particles out of the resin or ink. The substrate or web 310 carrying the printed coating material then passes a curing station (not shown), where UV radiation is applied to cure the coating material. Subsequently, the substrate or web is cut and / or folded to form the four-winged flights 100, in known manner. Embodiments of the invention are thus able to provide a dart flight having improved retention properties to prevent it being dislodged from the rear end of a dart flight stem in use. The need for a shaft ring used to hold the flight in 26 09 25 place may thereby be obviated, also avoiding the associated disadvantage of the shaft ring deflecting incoming subsequent darts . Dart flights with textured coatings may also have reduced drag and improved flight without loss of stability, depending on the throwing technique and preferences of the player. The coatings used in accordance with the present invention may be applied in a fast, reliable and cost-effective manner that can be integrated into existing dart flight production processes . Many adaptations of the principles and concepts outlined above will be apparent to the skilled person in view of the teaching contained herein. All such variations within the scope of the appended claims and their equivalents as properly assessed are intended to fall within the scope of protection defined by the claims. 26 09 25

Claims

1. A dart flight having multiple wings and having a front end arranged to be inserted into the rear end of a dart flight stem having elongate petals arranged to grip the wings of the flight between the petals, wherein at least a portion of the surface of one or more of the wings inside and / or outside the area to be gripped by the petals is provided with a coating, and wherein the coating is textured.

2. A dart flight according to Claim 1, wherein the coating is provided to said portion on both sides of each of the multiple wings.

3. A dart flight according to Claim 1 or 2, wherein the coating is selectively provided to said portion, such that said portion includes coated parts and uncoated parts .

4. A dart flight according to Claim 1, 2 or 3, wherein the coated parts are provided in a pattern of lines and / or or dots.

5. A dart flight according to any preceding claim, wherein the flight is made from polyester.

6. A dart flight according to any preceding claim, wherein said portion is inside the area to be gripped by the petals and the coating has a higher coefficient of friction with the petals of the dart flight stem than an uncoated wing of the flight.

7. A dart flight according to any preceding claim, whereinthe coating is a cured ink or a cured resin, optionally wherein the ink or resin has been cured by UV radiation.26 09 258. A dart flight according to any preceding claim, wherein the coating includes texture particles having a D(4,3) weighted mean diameter by volume from 1 pm to 150 pm, preferably from 10 pm to 100 pm, most preferably from 30 pm to 80 pm.

9. A dart flight according to Claim 8, wherein the ratio of the D(4,3) weighted mean diameter by volume of the texture particles to the average thickness of the coating is greater than 1.

10. A dart flight according to Claim 8 or 9, wherein the texture particles include inorganic particles, the inorganic particles optionally including particles of glass, ceramic, alumina, silica, aluminosilicates, and / or alumina coated on silica.

11. A dart flight according to Claim 8, 9 or 10, wherein the texture particles include organic particles, the organic particles optionally including particles of polyamide, nylon, polypropylene, polyethylene, polytetrafluoroethylene, ethylene copolymers, waxes, epoxy, and / or urea-formaldehyde.

12. A dart flight according to Claim 8, 9, 10 or 11, wherein the coating includes from 1% to 30% by weight of texture particles, preferably from 5% to 15% by weight of texture particles.

13. A dart flight according to any preceding claim, wherein said portion is inside the area to be gripped by the petals and the coating extends to at least a further portion of the surface of the at least one wing outside the area to be gripped by the petals, optionally wherein the coating extends to substantially the whole surface of each of the wings.26 09 2514. A method of manufacturing a dart flight comprising: providing a web of flight material;selectively applying a coating material to all or part of one side of the web, wherein the applied coating material forms a textured coating; andcutting and / or folding the web of flight material to form the wings of the dart flight.

15. A method of manufacturing a dart flight according to Claim 14, wherein the web of flight material is made from polyester, preferably having a thickness from 50 pmto 150 pm, more preferably having a thickness from 80 pmto 120 pm, most preferably having a thickness of 100 pm.

16. A method of manufacturing a dart flight according to Claim 14 or 15, wherein the coating material is a resin or an ink.

17. A method of manufacturing a dart flight according to Claim 14, 15 or 16, wherein the method further comprises curing the coating material by applying UV light and / or heat.

18. A method of manufacturing a dart flight according to any one of Claims 14 to 17, wherein selectively applying the coating material includes transferring the coating material onto the web of flight material from a flexographic roller.

19. A method of manufacturing a dart flight according to Claim 18, wherein selectively applying the coating material includes providing the coating material to the flexographic roller from an anilox roller.

20. A method of manufacturing a dart flight according to any one of Claims 14 to 19, wherein selectively applying the26 09 25coating material includes applying the coating material only to part of the one side of the web so that the wings of the dart flight include coated parts and uncoated parts, the selectively applying preferably being in a pattern of lines and / or or dots.

21. A method of manufacturing a dart flight according to any one of Claim 14 to 20, wherein the coating material includes texture particles having a D(4,3) weighted mean diameter by volume from 1 pm to 150 pm, preferably from 10 pm to 100 pm, most preferably from 30 pm to 80 pm.

22. A method of manufacturing a dart flight according to Claim 21, wherein selectively applying the coating material includes applying the coating material to a thickness such that the ratio of the D(4,3) weighted mean diameter by volume of the texture particles to the average thickness of the coating is greater than 1.

23. A method of manufacturing a dart flight according to Claim 21 or 22, wherein the texture particles include inorganic particles, the inorganic particles optionally including particles of glass, ceramic, alumina, silica, aluminosilicates, and / or alumina coated on silica.

24. A method of manufacturing a dart flight according to Claim 21, 22 or 23, wherein the texture particles include organic particles, the organic particles optionally including particles of polyamide, nylon, polypropylene, polyethylene, polytetrafluoroethylene, ethylene copolymers, waxes, epoxy, and / or ureaformaldehyde .

25. A method of manufacturing a dart flight according to Claim 21, 22, 23 or 24, wherein the coating material includes from 1% to 30% by weight of texture particles,preferably from 5% to 15% by weight of texture particles .26 09 25

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