GB2064967A - A dart stem - Google Patents

Abstract

A two-part dart stem has two freely rotatable male and female interfitting parts 22, 20. The rear part has a cruciform slot 32 for the dart flight. The rear part is of resilient plastics and the walls of the slot are sprung inwardly to firmly grip the dart flight. <IMAGE>

Description

SPECIFICATION A dart and dart stem This invention relates to a two-part dart stem and to a dart including such a stem.

Some dart players prefer to play with darts in which the flights can be freely rotated relative to the main part of the dart, if the dart flight is struck by a subsequently thrown dart. This free rotation is said to be advantageous in that the succeeding dart will be deflected less than it otherwise would have been.

Darts wherein the flights are rotatable have been suggested in British Patent Specifications Nos. 445 590 (Doel), 534289 (Farrington et al), 1 508075 (Roban) and 1 556806 (Elkadart Ltd).

In the said Roban Specification there is a proposal that the dart flight should be held in place by an arrangement of bifurcations forming jaws, the jaws having thereon axial ribs between which the material of the dart flight is clamped. A disadvantage of this construction is that the flight can normally wobble or tilt through a few degrees under a light applied force such as finger pressure. This departure of the flight from a truly coaxial location relative to the dart may mean that the flight of the dart through the air when thrown is not true, and perhaps more important, gives rise to doubts in the mind of the player who then may lack confidence in the dart and so throw below his best form. This point of course is of greater importance in championship play.It would be desirable if a dart and dart stem arrangemenu was available in which this wobbling or tilting is minimised or prevented and yet which exhibits the feature of a freely rotatable flight.

According to the invention, we provide a two-part dart stem having a first part with a male portion thereon and a second part having a circular-crosssection aperture therein, the two parts being freely relatively rotatable with the male portion extending into the aperture, in which the rear part is formed with a cruciform slot in the rear end, defined by planar walls, the width of each limb of the slot at its base being greater than its width at a region near the rear of dart stem and the material of the rear part being sufficiently resilient so that the portions thereof bounding the slot can be deformed outwardly by the insertion of a flight and grip the flight to hold it in position due to their own resilience.

With such an arrangement, the flight fins are gripped along substantially the whole axial length of the flight and moreover are gripped by substantially the whole of the planar areas bounding the slot.

Hence the possibility of tilting of the flight relative to the dart stem, as described above, is normally completely eliminated, resulting in a dart having the advantage of a secure flight mounting together with a freedom for the flight to rotate if struck by another dart.

In the preferred version of the invention, to facilitate insertion of the flight, a short rear end zone of each slot wall is chamfered, for example at about 45" to the stem axis, as seen in an axial plane. The first and second parts may be connected by a pin and bore connection of a snap-fit type, achieved by a ring-like bulge on the male part co-operating with an arcuate cross-section peripheral groove or channel on the inner wall of the aperture in the female part.

The male portion is preferabiy on or forms part of the rear part of the dart stem.

In this Specification, "front" and "rear" refer to the dart when travelling as in a normal throw, point forwards.

The first and second parts may be of synthetic plastics material. For example the front part may be moulded nylon and the rear part may be moulded from nylon or polycarbonate. The invention also provides a dart including a dart stem as aforesaid.

The invention will be better understood from the following illustrative and non-limiting description of an example of the invention, given with reference to the accompanying drawings in which: Figure l is a schematic axial cross-section of part of one example of a dart stem according to an example of the invention, on a scale enlarged compared to Figure 4.

Figure 2 is a schematic transverse cross-section on the line II - II in Figure 1.

Figure 3 is a schematic transverse cross-section on the line lil - lil in Figure 1, and Figure 4 is a schematic view of a dart including a dart stem as shown in Figure 1.

An example of a dart according to the invention is seen in Figure 4. It has a point 10, a metal barrel 12 with a threaded bore 14, a stem (also cailed a shaft or a cane) 16 and a 4-fin flight 18, for example made of polyester film. It is conventional for the bore 14to have a standard thread so that the stem 16 can be attached by screwing in. In the present invention, the stem is made in two parts 20 and 22, both of which may be moulded from plastics material, e.g. nylon or polycarbonate. The front part 20 has an axial bore 24 (Figure 1) therein which receives a substantially cylindrical pin 26 on the rear part 22. The pin 26 has a ring-like peripheral bulge 28 which can be received in a complementary circular groove 30 in the inner wall of the bore 24.With this construction, the parts 20 and 22 are connected by a snap fit and can easily be manually separated. This is of importance since the player may wish to exchange the rear part 22 if it has become damaged. Also the player may wish to exchange either of the parts 20 and 22 so that he can substitute a similar part of different length, in accordance with the teaching in our Patent No. 1 556 806. Moreover, with this construction, the parts 20 and 22 are freely relatively rotatable.

The rear part 22 carried the dart flight 18. A cruciform slot 32 is formed in the rear end of the rear part and as a result the rear portion of the part 22 is formed by four columns 34 (Figure 2) whose inner walls 36 are substantially planar. The width of each portion of the slot at its base, i.e. at its front end, is greater than its width elsewhere, and the material of the part 22 is such that the columns 34 can be sprung slightly outwardly. Figure 1 illustrates the material in its rest or undeformed position and in which the flight is not inserted. Figure 2 is a cross-section perpendicular to the stem axis showing the position of the columns 34 when the flight 18 is inserted.The columns 34 are deformed outwardly compared to the Figure 1 position and their planar faces 36 are in firm face-to-face contact with the flight fins over substantially the whole areas of these faces and in particular over substantially the whole axial length of the flight. With this arrangement, wobble of the flight under small forces, e.g. finger pressure when handling the dart before throwing, is substantially prevented. Of course, if a following dart should strike the flight at an angle then due to the pin and bore snap fit connection the rear part and the flight could freely rotate relative to the rest of the dart, in a similar way as would happen upon a similar occurrence in the case of the darts according to British Patents 445 590, 534289 and 1 508 075. The rear end position of the rear part 22 is chamfered or tapered as seen at 40, Figure 1, to provide a lead-in so that the flight can be inserted between the columns 34 without undue difficulty of manipulation. Another feature of this arrangement is that the flight may be dislodged in a rearward direction from its cruciform slot if the flight of a flying dart strikes an obstruction such as the flight of a dart already sticking in the dartboard. The security of attachment of the flight can be adjusted by appropriately choosing the resilience of the material of the part 22 and the angle of the faces 36 to the axis of the stem 16 in the rest position (Figure 1). The greater the angle, and the less the resiliency, the tighter will the flight be held in its cruciform slot.

Claims (9)

1. A two-part dart stem having a first part with a male portion thereon and a second part having a circular-cross-section aperture therein, the two parts being freely relatively rotatable with the male portion extending into the aperture, in which the rear part is formed with a cruciform slot in the rear end, defined by planar walls, the width of each limb of the slot at its base being greater than its width art a region nearthe rear of dart stem and the material of the rear part being sufficiently resilient so that the portions thereof bounding the slot can be deformed outwardly by the insertion of a flight and grip the flight to hoid it in position due to their own resilience.

2. A stem according to claim 1 in which to facilitate insertion of the flight, a short rear end zone of each slot wall is chamfered.

3. A stem according to claim 1 or 2 in which the first and second parts are connected by a pin and bore connection of a snap-fit type, achieved by a ring-like bulge on the male part co-operating with an arcuate cross-section peripheral groove or channel on the inner wall of the aperture in the female part.

4. A stem according to claim 3 in which the male portion is on or forms part of the rear part of the dart stem.

5. A stem according to any preceding claim in which the first and second parts are of synthetic plastics material.

6. A stem according to claim 2 or any claim dependent thereon in which the chamfer is at substantially 45" to the axis of the dart stem, as seen in an axial cross-sectional plane.

7. A stem according to any preceding claim in which the front part is of moulded nylon and the rear part is moulded from nylon or polycarbonate.

8. A two-part dart stem substantially as herein particularly described with reference to the accompanying drawings.

9. A dart including a two-part dart stem according to any preceding claim.