Dart barrel

Abstract

A barrel for a dart, and in particular a dart barrel having a textured surface. A dart barrel has a central longitudinal axis and is formed of at least first 10 and second 20 longitudinal portions. Th

Description

Field of the Invention The present invention relates to a barrel for a dart, and in particular to a dart barrel having a textured surface. Background of the Invention Darts is a well-known and popular game in which aerodynamic projectiles (the darts) are thrown at a circular target (the dart board) and in which the points scored depend on the area on the dartboard in which the dart becomes embedded. Each dart usually comprises a sharpened point at one end for embedding in the dartboard and a "flight" or flight assembly consisting of a flight inserted into a shaft element at the other end to enable the dart to fly through the air towards the dartboard when thrown by the player. The barrel is a middle or body section of the dart located between the piercing tip at its front and the flight section at its rear. The barrel is what the player uses to hold the dart and also provides the majority of the weight of the dart. The barrel typically has surface texture, such as knurling or grooves, which helps the player to grip the dart. A better grip allows the player better to control their throw and, thereby, better and more accurately to project the dart at the target. The present invention seeks to provide an improved dart barrel. Summary of the Invention According to an aspect of the invention, there is provided a dart barrel having a central longitudinal axis and being formed of at least first and second longitudinal portions, wherein an orthogonal cross section through the first longitudinal portion is in the form of a first polygon having n sides and an orthogonal cross-section through the second longitudinal portion is in the form of second polygon having 2n sides; wherein the first and second polygons are each radially symmetric about the longitudinal axis; and wherein corners of the first polygon are each rotationally aligned with a point on a straight side of the second polygon lying between the corners at either end of said side. By this arrangement, each corner of the first polygon is arranged such that a plane containing said corner and the longitudinal axis bisects a straight side of the second polygon nearest said corner. The inventors have realised that this combination of longitudinal portions with interacting polygonal geometries produces a dart barrel providing an exceptional grip. With such a shape, exposed corners of the polygonal portions provide a gripping texture, while flat surfaces on the exterior surface provide a comfortable point of contact for the player. Together these features make the dart barrel particularly manipulable, improving the ease and accuracy with which it may be thrown. In some embodiments, each longitudinal portion has a uniform cross section along its length. Principally, this allows the dart barrel to be manufactured more simply. The barrel may have a further first or a further second longitudinal portion, wherein the second longitudinal portion is disposed between said first longitudinal portions or the first longitudinal portion is disposed between said second longitudinal portions. Additional, repeated interacting portions further increase the grippability of the barrel. The further first longitudinal portion may be rotationally offset about the longitudinal axis relative to the first longitudinal portion such that respective corners of the respective first polygons are rotationally misaligned. Similarly, the further second longitudinal portion may be rotationally offset about the longitudinal axis relative to the second longitudinal portion such that respective corners of the respective second polygons are rotationally misaligned. This rotational offset between similar longitudinal portions provides additional variation in the surface of the barrel which further improves the grip, particularly by increasing the number of directions in which slipping movement is resisted by the surface texture. Preferably, the dart barrel includes repeated longitudinal units, wherein each longitudinal unit is formed of said first and second longitudinal portions. The surface texture may be replicated along the dart barrel. Further, it is preferred that at least some of the longitudinal units abut one another. It is particularly preferred that the first longitudinal portion of a first longitudinal unit neighbours the second longitudinal portion of a second longitudinal unit, or the first longitudinal portion of a second longitudinal unit neighbours the second longitudinal portion of a first longitudinal unit. Junctions between polygonal portions, at which corners of the polygons are exposed, provide the gripping effect, and this is maximised where the polygons abut one another. Preferably, the dart barrel includes first and second longitudinal units, wherein said second longitudinal unit is rotationally offset from said first longitudinal unit about the longitudinal axis such that respective corners of the respective first polygons are rotationally misaligned. As described above, a rotational offset between similar polygons provides additional variation in the surface texture that increases gripping interaction with the player's hand. It is particularly preferred that the corners of the first polygon of the second longitudinal unit are each rotationally aligned with a midpoint of a straight side of the first polygon of the first longitudinal unit. For a given shape, the exposed corners are able to protrude most prominently at the surface, and thereby provide the greatest grip, where they bisect a straight side of the opposing polygon at the halfway-point of said side. In preferred embodiments, the first and second polygons are regular polygons. Regular side lengths greatly simplify manufacture of the barrel. In this way, relatively few separate cutting operations can be used to provide a greatly enhanced gripping surface. Preferably, n is 5, 6, 7 or 8, most preferably n=6. A polygon with very few sides tends to protrude excessively at its corners, making the barrel less comfortable for the player to hold, and a polygon with very many sides tends to protrude minimally at its corners, making the surface of the barrel less effective at producing friction. Polygons with sides as defined by the values above are considered to provide the best performance. The diameters of the first and second polygons may be the same. The diameters of the first and second polygons may be different. In practical embodiments, the first and second polygons each have a diameter in the range from 3mm to 10mm, preferably from 4mm to 8mm, more preferably from 5mm to 7mm. Advantageously, alternate straight sides of the second polygon may be coincident with straight sides of the first polygon such that flat surfaces extend longitudinally across neighbouring first and second longitudinal portions. The advantage of this arrangement is two-fold: firstly, the number of separate cuts required to machine the barrel is reduced, making the barrel cheaper and quicker to produce, and reducing the potential for error in manufacturing; and, secondly, the resulting flats or lands provide a smooth comfortable surface between the corners for the player to grasp. The dart barrel may include a sharp tip at one end. The dart barrel may include a connector at one end, such as an internal threaded section, for connecting to a flight assembly. The dart barrel is preferably made of metal, most preferably tungsten. According to another aspect of the invention, there is provided a dart including a dart barrel as recited above. Preferred features of all described aspects and embodiments are combinable with other aspects and embodiments. Brief Description of the Drawings ..................................................................................................................................................1.....................................................111.............."...................................................................................................................................................................................... Embodiments of the present invention are described below, by way of example only, with reference to and as illustrated in the accompanying drawings, in which: Figure 1 is a schematic drawing of a dart barrel in a profile view; Figure 2 shows the dart barrel of Figure 1 in an isometric view; Figure 3 shows an orthogonal cross-section of the dart barrel of Figures 1 and 2; Figure 4 is a schematic drawing of a second dart barrel in a profile view; Figure 5 shows the dart barrel of Figure 4 in an isometric view. Description of Preferred Embodiments Described below are dart barrels which have a surface shape that provides improved grippability. Figure 1 shows a first dart barrel in profile. The dart barrel has a central longitudinal axis and is made up of a series of longitudinal portions arranged along the longitudinal axis. The arrangement of longitudinal portions can easily be seen in Figure 2. The dart barrel includes first longitudinal portions 10 and second longitudinal portions 20, the orthogonal cross sections of which are each polygonal in shape. That is, the exterior surface of each of the first and second longitudinal portions 10,20 is formed of straight sides and angular corners. The dart barrel is generally radially symmetric in shape. That is, at any point along its length the barrel has a cross-section (in a plane orthogonal to the longitudinal axis) which can be divided into identical repeated sections arranged around a central point (which lies on the longitudinal axis) so that if one were to turn the barrel around this point there would be more than one instance in the course of a complete rotation at which the cross-section would look the same. This radial, or rotational, symmetry ensures that the barrel's centre of mass lies on the longitudinal axis and thereby helps the barrel to be stable and predictable in flight. Importantly, the first longitudinal portions 10 have a different polygonal shape to the second longitudinal portions 20. In particular, the second longitudinal portions 20 each have a perimeter (at the exterior surface of the barrel) with twice as many sides as the perimeter of each of the first longitudinal portions 10. In this embodiment, a cross-section taken through the first longitudinal portion 10 has the shape of a hexagon, and a cross-section taken through the second longitudinal portion 20 has the shape of a dodecagon. The first and second portions 10,20 are rotationally oriented relative to each other such that corners of the first portion 10 are each rotationally, or circumferentially, aligned with a point on a straight side of the second portion 20 (said point lying between the corners at either end of said side). That is, each corner of the first portion 10 is arranged such that a plane containing said corner and the longitudinal axis bisects a straight side of the second portion 20 nearest said corner. In other words, corners of the hexagon of the first portion 10 are misaligned with adjacent corners of the dodecagon of the second portion 20. In this way, the exterior surface of the barrel includes a series of interposed flat sides and protruding corners, as can be seen in Figure 2. These protruding or exposed corners provide a frictional gripping action against the hand of a person holding the barrel. With reference to Figure 2, alternate straight sides of the perimeter of the second longitudinal portion 20 (that is, every other side of the dodecagon) are coincident with straight sides of the perimeter of the first longitudinal portion 10 (that is, the straight sides of the hexagon) such that flat surfaces extend longitudinally across neighbouring first and second longitudinal portions 10,20. The first and second longitudinal portions 10,20 are replicated along substantially the length of the barrel in repeating longitudinal units. In this embodiment, the dart barrel comprises first longitudinal units 100 and second longitudinal units 200, each of which comprises first longitudinal portion 10 and second longitudinal portion 20. The second longitudinal units are rotationally offset from the first longitudinal units 100 about the longitudinal axis such that respective corners of the respective hexagons are rotationally misaligned. This relative orientation of the hexagons is shown in Figure 3. In particular, the corners of the hexagon of the second longitudinal unit 200 are each rotationally or circumferentially aligned with a mid-point of a straight side of the hexagon of the first longitudinal unit 100. The first and second longitudinal units 100,200 neighbour (that is, abut) each other and are arranged so that a repeating pattern is formed, whereby the first longitudinal portion 10 of each second longitudinal unit 200 neighbours the second longitudinal portion 20 of a first longitudinal unit 100. Returning to Figure 2, it can be seen that the rotational offset between the first and second longitudinal units 100,200 breaks up, or separates, the flat surfaces which extend across neighbouring first and second longitudinal portions 10,20 along the barrel. This creates a pattern of tessellated crosses on the surface of the barrel. However, various arrangements of longitudinal portions and units can be used. For example, Figure 4 shows a second dart barrel with a different arrangement. This dart barrel also comprises first longitudinal portions 30 and second longitudinal portions 40, which are identical to those of the first dart barrel described above. The second dart barrel differs significantly from the dart barrel of Figures 1-3 only in a few respects which are described below. Firstly, this dart barrel has longitudinal units 300 which are each formed of a single first longitudinal portion 30 disposed between, and neighboured by, opposing pairs of second longitudinal portions 40. Secondly, this dart barrel does not have rotationally offset second longitudinal units. Thirdly, the longitudinal units 300 do not abut other polygonal longitudinal units as in the first dart barrel, but, instead, are separated by sets of annular grooves and ridges, as shown most clearly in Figure 5. In the dart barrels described above, both the hexagons of the first portions 10,30 and the dodecagons of the second portions 20,40 are regular polygons (when taken in an orthogonal cross-section to the longitudinal axis). In the dart barrels described above, each of the first and second longitudinal portions 10,20,30,40 also has a uniform crosssection along its length. These features each greatly simplify manufacture of the dart barrel but are not necessary in every embodiment. Similarly, in the dart barrels described above, only two different polygons are used in first and second longitudinal portions 10,20,30,40. It will be appreciated that further or alternative longitudinal portions with many different polygonal cross-sections can be used in various combinations. However, complexity of manufacture increases rapidly when introducing more polygons and more intricate patterns. Both dart barrels described above are made of metal, in particular tungsten. However, other materials can be used. All optional and preferred features and modifications of the described embodiments and dependent claims are usable in all aspects of the invention taught herein. Furthermore, the individual features of the dependent claims, as well as all optional and preferred features and modifications of the described embodiments are combinable and interchangeable with one another.

Claims

1. A dart barrel having a central longitudinal axis and being formed of at least first and second longitudinal portions,wherein an orthogonal cross-section through the first longitudinal portion is in the form of a first polygon having n sides and an orthogonal cross-section through the second longitudinal portion is in the form of a second polygon having 2n sides;wherein the first and second polygons are each radially symmetric about the longitudinal axis; andwherein corners of the first polygon are each rotationally aligned with a point on a straight side of the second polygon lying between the corners at either end of said side.

2. The dart barrel according to claim 1, wherein each longitudinal portion has a uniform cross section along its length.

3. The dart barrel according to claim 1 or 2, having a further first or a further second longitudinal portion, wherein the second longitudinal portion is disposed between said first longitudinal portions or the first longitudinal portion is disposed between said second longitudinal portions.

4. The dart barrel according to claim 3, wherein the further first longitudinal portion is rotationally offset about the longitudinal axis relative to the first longitudinal portion such that respective corners of the respective first polygons are rotationally misaligned.

5. The dart barrel according to claim 3, wherein the further secondlongitudinal portion is rotationally offset about the longitudinal axis relative to the second longitudinal portion such that respective corners of the respective second polygons are rotationally misaligned.

6. The dart barrel according to any preceding claim, including repeated longitudinal units, wherein each longitudinal unit is formed of said first and second longitudinal portions.

7. The dart barrel according to claim 6, wherein at least some of the longitudinal units abut one another.

8. The dart barrel according to claim 7, wherein the first longitudinal portion of a first longitudinal unit neighbours the second longitudinal portion of a second longitudinal unit, or the first longitudinal portion of a second longitudinal unit neighbours the second longitudinal portion of a first longitudinal unit.

9. The dart barrel according to any of claims 6-8, including first and second longitudinal units, wherein said second longitudinal unit is rotationally offset from said first longitudinal unit about the longitudinal axis such that respective corners of the respective first polygons are rotationally misaligned.

10. The dart barrel according to claim 9, wherein corners of the first polygon of the second longitudinal unit are each rotationally aligned with a mid-point of a straight side of the first polygon of the first longitudinal unit.

11. The dart barrel according to any preceding claim, wherein the first and second polygons are regular polygons.

12. The dart barrel according to any preceding claim, wherein n is 5, 6, 7 or 8.

13. The dart barrel according to claim 12, wherein n=6.

14. The dart barrel according to any preceding claim, wherein alternate straight sides of the second polygon are coincident with straight sides of the first polygon such that flat surfaces extend longitudinally across neighbouring first and second longitudinal portions.

15. The dart barrel according to claim 1, comprising at least neighbouring first and second longitudinal units, each of the first and second longitudinal units having first and second longitudinal portions, each of said first and second longitudinal portions having a uniform cross-section along its length, wherein the second longitudinal portion of the first longitudinal unit abuts the first longitudinal portion of the second longitudinal unit, wherein the second longitudinal unit is rotationally offset from the first longitudinal unit about the longitudinal axis such that respective corners of the respective first polygons are rotationally misaligned, and wherein the first polygon of each of said longitudinal units is a regular hexagon and the second polygon of each of said longitudinal units is a regular dodecagon.

16. The dart barrel according to claim 1, comprising repeated longitudinal units,each of the longitudinal units having a first longitudinal portion disposed between, and neighboured by, opposing pairs of second longitudinal portions,each of said first and second longitudinal portions having a uniform cross-section along its length,wherein the longitudinal units are separated from one another longitudinally, and5 wherein the first polygon of each of said longitudinal units is aregular hexagon and the second polygon of each of said longitudinal units is a regular dodecagon.

17. The dart barrel according to any preceding claim, including a10 sharp tip at one end.

18. A dart including a dart barrel according to any preceding claim.

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