FIELD OF THE INVENTION

The present invention relates to injection moulding of long hollow items, especial- ly hollow handles or shafts for tools, in particular cleaning tools.

BACKGROUND OF THE INVENTION

A moulding method for producing tubes that are open at both ends is disclosed in international patent application WO2009/138431 by Waid et al. The method corn- prises a projectile-type push member that is accelerated by fluid pressure through the mould from one end to the other end and out of the mould, leaving a tube which is open at both ends. A moulding method with a projectile is also disclosed in Japanese patent application JPH 06 320565 A, in which a spherical projectile is accelerated to the other end of the mould, which end is cut off after the moulding in order to leave a bent tube with open ends. JPH08229993 concerns an injection moulding process with a spherical push member.

In the prior art, handles for cleaning tools are traditionally produced as tubes, either in one piece or in telescopic form, although these tubes are not produced by the projectile moulding methods of the above-mentioned prior art. Often sim- pler production techniques are used.

Unfortunately, tubes have a general disadvantage in hygiene sensitive area, such as in food industry, for example slaughter houses, because long handles for brooms and floor scrapers should have a smooth surface and no ends with edges, grooves, and pockets in which dirt and bacteria can accumulate.

Instead of using single tubes and telescopic handles and cover the end with a closing material, it is of advantage if the handle is produced as a single piece. And in order for the handle to be light-weight, it is best if it is hollow. A possible method for production of single-piece hollow handles is by injection moulding with a mould core. Long handles may be injection moulded with a mould core that remains inside the handle. However, these are disadvantageous in hav- ing a relatively high weight, whereas the weight is desired to be as low as possi- ble.

An improved example of production of a long hollow handle by injection moulding is given in international patent application WO0234494 by Sorensen, assigned to H.P. Industrial. In this disclosure, the core is removed from the hollow tube by pressurized air.

However, a number of problems have been recognised by injection moulding a long tubular item while using a mould core, if this mould core is not supported at both ends. One of the problems is non-uniform pressure action of the injected mass on the mould core, which results in the mould core deflecting to a side with a not centred hole as consequence, resulting in a lack of balanced weight distribu tion.

In order to overcome this, international patent application WOO/3090991 by Sorensen, assigned to H.P. Industrial proposes injection moulding of a long, tubu- lar item that is closed at one end, wherein the method uses rotation of the mould core. Although, this works satisfactory in the rotation stabilizing the core, it is a complex moulding procedure and apparatus.

DE102013010541 concerns RIT (rocket injection techniques), wherein a rocket, i.e. a projectile with its own propulsion means is used in a moulding process. In contrast, the push member of the present invention does not comprise propulsion means.

It would be desirable to provide an injection moulding process for a long hollow handle in which such complex system is avoided while maintaining the advantage of producing light-weight handles with a precise weight distribution. SUMMARY OF THE INVENTION

It is an objective of the invention to provide an improvement in the art. In par- ticular, it is an objective to provide an improved manufacturing method for injec- tion moulding a long or elongated, tubular tool handle, in particular a handle for a cleaning tool, for example a broom or floor scraper, said method comprising a push member. This purpose is achieved by methods, systems and devices, as described in the following.

In particular, the current invention concerns:

• A push member for injection moulding of a hollow item such as a handle, said item comprising a massive end section, said push member comprising : a stem and a head, wherein said head is wider than the stem; wherein said push member comprises integration means for integrating of the push member with the shaft, such as with said massive end section, during injection moulding.

• A hollow item such as a handle or shaft comprising a push member as dis closed above.

• A method of injection moulding a hollow item, such as a shaft for a cleaning tool, said method comprising the use of a push member as disclosed above.

• A method for providing a cleaning tool with a handle, the method comprising providing a handle by a method as disclosed above, and mounting the handle on a cleaning tool while maintaining the upper compacted solid, non-hollow, rear end part of the handle as a protective closure of the handle against intru- sion of liquid and dirt when being used with the cleaning tool.

• An injection mould for a push member as disclosed above.

• An injection mould for a method as disclosed above, wherein the injection mould comprises an injection moulding cavity shaped as a template for the handle in addition to a further injection moulding cavity shaped as a template for the push member for simultaneous moulding of a handle and a push mem- ber.

• A handle provided by a method as disclosed above.

• A cleaning tool with a handle as disclosed above, wherein the cleaning tool is a broom or floor scraper. SHORT DESCRIPTION OF THE DRAWINGS

The invention will be explained in more detail with reference to the drawing, where:

FIG. 1 illustrates an injection moulding apparatus,

FIG. 2 a) shows one half section of a handle, b) an enlarged view of the rear end part and c) an enlarged view of the front end part;

FIG. 3 shows a broom and a floor scraper as examples for cleaning tools; and FIG. 4 shows examples of push members, a) elongated push member, b) short push member with a partial tail, c) push member of intermediate length with a non-rotational-symmetric tail.

DETAILED DESCRIPTION OF THE INVENTION

A compact injection moulding procedure is described for a long tubular thermo- plastic handle with an only partly through-going hole in a longitudinal direction of the handle. In the context of the present invention, the terms "handle" and "shaft" can be used interchangeably.

For production of the handle by injection moulding, a push member is moved by pressurised fluid centrally from one end in the mould cavity towards the opposite end in order to form a longitudinal cavity inside the formed polymer handle. The fluid is typically gas, such as air or nitrogen, although also liquid can be used in principle. Details are explained in the following.

The method comprises providing an elongated injection moulding cavity with a longitudinal axis, for example straight axis, although a slight bending for a better ergonomic shape of the handle is possible.

The elongated injection moulding cavity is provided with a first end region and an opposite second end region and a tubular inner wall surrounding the cavity be- tween the first and second end regions. The inner wall of the cavity surrounds the formed handle and, thus, acts as a template for the outer wall of the hollow han- dle.

For example, the longitudinal axis is oriented in vertical orientation or largely ver- tical orientation; in this orientation, the cavity has a first end regions that is a lower end region and an opposite second end region that is an upper end region. The cavity is surrounded by a vertical tubular inner wall between the lower end region and upper end region. A push member with a diameter less than a diameter of the inner wall of the cavi- ty is provided inside the first end region of the cavity. While the push member is inside the first end region, molten thermoplastic polymer is injected into the cavi- ty. Subsequently pressurised fluid, for example pressurised gas, such as air, is provided into the first end region of the cavity, and the push member pushed to- wards the second end region by the pressurised fluid, thereby causing the push member to push part of the molten polymer towards the second end region and to distribute the molten polymer against an inner wall of the cavity between the push member and the inner wall.

For example, for the embodiment with the vertical orientation, the push member is provided inside the cavity in the lower end region of the cavity. While the push member is inside the lower end region of the cavity, molten thermoplastic poly- mer is injected into the cavity, optionally at a location above the push member, for example about half way between the upper and lower end regions, which cause the polymer to flow in the cavity by gravity downwards to the lower end region. As the push member has a diameter less than a diameter of the inner wall, the polymer flows around the push member. Subsequently, pressurised fluid is supplied behind the push member and drainage of air in front of the push member until the push member comes to a halt at the second end region of the cavity by compacting remaining molten polymer at the second end region, forming a solid, non-hollow, rear end part of the handle by the compaction.

For example, for the embodiment with the vertical orientation, pressurised fluid, for example gas, is provided into the lower end region of the cavity below the push member for pushing the push member upwards towards the upper end re- gion by the pressurised fluid, for example gas, thereby causing the push member to push molten polymer towards the upper end region and to distribute the mol- ten polymer sideways against the inner wall of the cavity between the push mem- ber and the inner wall. Pressurised fluid, for example gas, is continuously supplied below the push member while air is drained from the cavity volume above the push member until the push member has pushed all remaining polymer towards the upper end of the cavity and comes to a halt at the upper end region while compacting remaining molten polymer into an upper end part of the formed han- dle. The first phase of the injection moulding from injection of the molten thermo- plastic polymer and until the polymer reaches the push member and flows around it, lasts typically in the order of one to two seconds. The phase where the push member is pushed towards the second end region by the pressurised fluid, for example gas, takes only a fraction of a second. The entire moulding process typi cally lasts a few seconds. After solidifying the molten polymer to form the handle, the hollow handle is removed from the cavity.

The compaction forms an upper solid, non-hollow, rear end part of the handle after solidification.

Typical fluid pressures, for example gas pressures, are in the range of 10-100 bar, for example 30-80 bar, optionally around 50 bar.

Advantageously, the push member is provided as a polymer member and inte- grated into the remaining molten polymer during compaction. If the push member is made in the same polymer as the handle, it is typically in a partly molten state when it gets integrated in the remaining molten polymer during compaction.

Typically, the handle is injection moulded with an open end from the lower end region of the cavity. In order to prevent intrusion of liquid and dirt into the inner cavity of the handle, the open end is advantageously closed with polymer in order to provide a closed inner cavity inside the handle.

For providing an eyelet for hanging the handle on a hook, the rear end part of the handle is optionally injection moulded with a through-going opening extending transversely through the solid rear end part.

In order to provide a light-weight handle, some embodiments of the method corn- prise pushing the push member by the pressurised fluid over a distance that is at least twenty times the average diameter of the hole for providing an equally long cavity length inside the handle.

The diameter of a hole in a handle for common use in cleaning tools will typically be between 18 and 30 mm, and also 32 mm. The length of such handles is usual- ly between 0.4 and 2 m. The inventors have found that the use of a spherical push member is problematic, as a spherical push member tends to "zig-zag" under propulsion, resulting in e.g. uneven wall thickness, which is undesirable. In some embodiments, the push member is provided with a head and a stem at a rear end of the head, optionally the head having a larger diameter than the stem. Advantageously, the head has a tapered front portion with a decreasing diameter towards a front end of the head for pushing the molten polymer to the side of the head towards the inner wall of the cavity during movement of the push member towards the second end region of the cavity. It is understood that the push mem- ber is oriented in the moulding cavity with the front end of the head towards the second end in the cavity prior to injection moulding.

It has been proven useful to provide the push member with a hollow stem in which the fluid is accumulated when the push member is pressed towards the second end.

As it appears from the above, the push member takes a role in the cavity similar as an accelerated projectile when being pushed towards the upper end.

In some practical embodiments, an injection mould is provided with an injection moulding cavity having an inner wall shaped as a template for the outer side of the handle in addition to a further injection moulding cavity shaped as a template for the push member. In this embodiment, a single injection moulding sequence is used for injection moulding the push member as well as the handle, for example simultaneous moulding of a handle and a push member. Thereby, a push member is produced each time a handle is produced that can be used subsequently for the injection moulding of the handle. For fastening of the handle to a tool that is not yet provided with a handle, espe- cially cleaning tool, such as a broom or floor scraper, the handle is advantageous- ly moulded with a fastener at a front end part, which is opposite the rear end part. Examples of fasteners are threads for cooperation of a similar threading in the tool, or a bayonet fastener.

By a method according to the invention, it is possible to make tubular items where the length of the partly through-going hole in the item is at least ten, fif teen or at least twenty times the average diameter of the hole. Especially, it is thereby possible to make stable handles for cleaning tools, such as brooms, with a length of one to two meter.

The invention also relates to a method for providing a cleaning tool with a handle, the method comprising providing a handle 2 by an injection process disclosed herein, and mounting the handle on a cleaning tool while maintaining the upper compacted solid, non-hollow, rear end part 2c of the handle 2 as a protective clo- sure of the handle 2 against intrusion of liquid and dirt when being used with the cleaning tool. Examples of such cleaning tools may comprise a broom or floor scraper. Said method of providing a cleaning tool may comprise fastening the handle 2 to the cleaning tool.

Further, the invention also concerns a handle 2 provided by an injection moulding method as disclosed herein. Said handle 2 may comprise a closed front end part 2c with a fastener 3 for fastening the handle 2 to a cleaning tool and a closed rear end part 2b at the opposite end of the handle 2. Said rear end part 2b usually comprises a solid end section 8 and optionally a transversely through-going hole 11 at a first end of the solid end section 8 for hanging the handle 2 on a hook and with a push member 9 at a second end of the solid end section 8 adjacent to a hollow cavity inside the handle 2, the hollow cavity 5 inside the handle 2 extend- ing between the front end and rear end part 2c, 2b. Often, the length of the cavi- ty 5 inside the handle 2 is at least twenty times the average diameter of the cavi- ty. The average diameter of the cavity 5 can e.g. be between 18 and 30 mm; and the length of the handle 2 can between 0.4 and 2 m.

The invention also concerns a cleaning tool with a handle as disclosed herein. Such cleaning tools can e.g. be a broom or a floor scraper, or similar tools.

Examples for thermoplastic polymers for moulding a handle as described herein are polyolefins, for example polypropylene. However, other thermoplastic poly- mers can be used, for example polyester (polyethylene terephtalate).

Optionally, reinforcing fibres are added to the molten polymer, for example glass fibres, carbon fibres, Kevlar fibres, plant fibres.

Optionally, further agents such as mineral fillers, barium sulphate, talc powder or chalk can be added to the polymer. FIG. la illustrates a first half la of an injection mould, and FIG. lb illustrates the other half lb as a counterpart for moulding a thermoplastic material when the two halves la, lb are abutting each other. The mould is used for producing a handle 2 as illustrated in FIG. 2, for example used for a broom. FIG. 2b illustrates a rear end part 2b of the handle 2 and FIG. 2c a front end part 2c of the handle 2, the front end part of the handle is subsequently mounted to a cleaning tool.

As illustrated best in FIG. 2c, the second end part 2c is comprises a narrowing section 7 and is provided with a thread 3 at the end for connection to a cleaning tool. As alternative to the thread, other attachment mechanisms could be used, for example as a bayonet-mount or a simple conical connector that is held by fric- tion.

The handle 2 is mostly hollow with an internal hollow cavity 5 inside a handle wall 4, the cavity extending along most of the length of the handle in order to save weight and material. The rear end part 2b, as best illustrated in FIG. 2b comprises a solid, massive, not hollow end section 8 with an eyelet 11 for hanging the han- dle 2 onto a hook. Attention is drawn to a push member 9, which can be shaped as a mushroom with a stem 9a that has an inner hollow cavity 9c and a thickened end 9b at the end of the stem. Generally, the outer diameter of the thickened end or head 9b is wider than the outer diameter of the stem 9a, thus contributing to the "mushroom-like" appearance. The function of the mushroom-shaped push member will be ex- plained in the following with reference to FIG. la.

The first mould half la comprises two identical mould cavities 12 for producing two handles 2 at a time. The orientation of the first mould half la and the second mould half lb when combined into a mould form is such that the mould cavity 12 for the handle 2 is vertical with the upper end 12b being located where the solid end section 8 at the rear end part 2b the of the handle 2 is located. The lower end 12c of the mould cavity 12 comprises a narrowing cavity section 17 for forming the corresponding narrowing section 7 of the handle and with a threading forming cavity section 13 for forming the thread 3 of the handle 2. Four circular grooves 14 are provided for shaping the handle with a corresponding number of four col- lars for a better grip of the handle 2. Prior to closing the mould form with the two halves la, lb, the mushroom formed push member 9, that is illustrated in FIG. 2b and FIG. 2c is inserted into the nar- rowing cavity section 17 at the lower end 12c.

Once the mould is closed, molten thermoplastic polymer is inserted into the cavity 12 through canals 16. The vertical orientation of the cavity 12 results in the ther- moplastic polymer flowing down to the lower end region 12c of the cavity 12. A relatively low viscosity of the polymer due to the high temperature results in the polymer reaching the mushroom shaped push member. The diameter of the head 9b of the push member 9 is less that the inner diameter of the lower end region 12c so that the polymer flows also around the push member 9. At this stage, most of the polymer is in the lower part 12c, embedding the push member 9 in- side the molten polymer. At this stage, a lower opening 18 in the mould is provid- ed with pressurised air, accelerating the push member 9 towards the upper end 12b of the cavity within less than a second. The upper end 12b of the cavity 12 is provided with a small exhaust opening such that air can be vented from the cavity 12 while the push member 9 is pressed towards the upper end 12b, pushing the molten polymer in front of the push member 9 on its path towards the upper end 12b. However, as the push member 9 has a diameter narrower than the inner diameter of the cavity 12, part of the polymer is distributed by the push member 9 against the inner wall of the cavity 12, forming a hollow handle. Once, the push member reaches the upper end 12b of the cavity, the molten polymer is corn- pressed into a massive block that forms the massive end section 8 at the rear end part 2b of the handle 2.

As best illustrated in FIG. 2b, with the white push member 9, the push member 9 gets integrated in the massive end section 8 of the handle 2. For proper accelera- tion and stable movement of the push member 9 inside the cavity, the push member 9 advantageously has a hollow cavity 9c inside the push member stem 9a; other stabilizing means can be present as well.

In particular, a push member 9, according to the invention, suitable for injection moulding of a hollow item such as a handle 2, said hollow item comprising a mas- sive end section 8, may comprise a stem 9a and a head 9b, wherein said head 9b is wider than the stem 9a; and integration means for integrating the push mem- ber 9 with the shaft 2, such as with said massive end section 8, during injection moulding. Said integration means may comprise one or more of: (i) a cavity 9c within said stem 9a, said cavity 9c optionally extending into said head 9b; (ii) one or more opening(s) 9d within stem 9a, said opening(s) 9d optionally being in fluid connec- tion with cavity 9c; (iii) one or more further cavity(ies) 9e, said further cavity(ies) 9e providing at least in part a thinner outer wall of head 9b; and/or (iv) one or more indentation(s) 9g on said head 9b.

A push member 9, according to the invention, may comprise (i) a cavity 9c within said stem 9a, said cavity 9c optionally extending into said head 9b, and one or more of: (i) one or more opening(s) 9d within stem 9a, said opening(s) optionally being in fluid connection with cavity 9c; (ii) one or more further cavity(ies) 9e, said further cavity(ies) 9e providing at least in part a thinner outer wall of head 9b; and/or (iii) one or more indentation(s) 9g on said head 9b.

A push member 9, according to the invention, may possess a ratio of length of stem 9a to height of head 9b in the range of 4: 1 to 1 : 1 in length.

A push member 9, according to the invention, may possess a ratio of length of stem 9a to height of head 9b in the range of 1 : 1 to 1 : 10; such as 1 :2-1 :6 or 1 :3- 1 : 5.

A push member 9, according to the invention, may possess mirror- inverted sym- metry. Said push member 9 may also possess rotational symmetry along its lon- gitudinal axis. Assessment of said mirror-inverted symmetry and/or rotational symmetry may include or exclude one or more of said integration means.

A push member 9, according to the invention, may possess a ratio of length of stem 9a to height of head 9b of around 1 :2-1 :6 or 1 :3-1 : 5. Furthermore, said stem 9a may comprise at least one aperture 9d extending from the base of the head 9b to the end of the stem 9a. Said aperture 9d can be in fluid connection with cavity (9c), e.g. as illustrated in Fig 4 b and c.

The maximum width of head 9b contributes to the thickness of handle/shaft wall 4. In some embodiments, said maximum width of head 9b is smaller than the average inner diameter of said hollow shaft wall 4. In some embodiments, said maximum width of head 9b is 0.5-5 mm smaller than the average inner diameter of said hollow shaft wall 4, such as around 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0 mm. In some embodiments, said maximum width of head 9b is around 0.5-1.0,1.0-1.5, 1.5-2.0,1.5-2.0, 2.0-2.5, 2.5-3.0, 3.0-3.5, 3.5-4.0, 4.0-4.5, or 4.5-5.0 mm smaller than the average inner diameter of said hollow shaft wall 4. The current invention also concerns a hollow item such as a handle or shaft (2) comprising a push member (9) as disclosed herein. The hollow item and the push member (9) may consist essentially of the same material, such as the same thermoplastic polymer. Hollow item and/or push member may also comprise rein- forcing fibres, and/or further agents.

In some embodiments, the hollow item may comprise fastening means, such as an eyelet or the like for hanging the hollow item on a hook.

Once, the handle 2 has been formed, it is removed from the mould. The open channel 15 at the front end 2c of the handle 2 is closed with polymer in order to seal the internal hollow cavity 5 of the handle 2 so that cleaning of the handle 2 is easy without pockets and edges that could accumulate bacteria and/or dirt.

The mould has an optional additional mould section 19 in which the mushroom shaped push-members 9 are formed. The additional mould section 19 comprises two mushroom shaped cavities 20 and a flange 21 with rods 22 that form the hol low inner part 9c of the mushroom shaped push member 9. During moulding of the two handles 2 in the cavities 12, simultaneously, also two new push members 9 are moulded in the additional mould section 19. These two push members 9 are then used in the moulding process for the subsequent moulding procedure where two additional handles 2 are moulded.

FIG. 3 shows a broom and a floor scraper as examples for cleaning tools with handles or shafts, according to the present invention. A person skilled in the art will know further suitable applications for tubular handles or shafts provided, ac- cording to the present invention.

Further embodiments of suitable push members 9, according to the present in- vention, are illustrated in FIG. 4. FIG. 4a shows an elongated push member 9 with a longer stem 9, FIG. 4b shows a push member with a short and only partial stem 9a. Fig 4c shows an c) push member with a stem of intermediate length with a non-rotational-symmetric tail.

The stem 9a comprises a cavity 9c. The cavity 9c can be cylindrical, i.e. with a stem wall of even thickness, or it can be e.g. conical, such that the wall thickness is thinner towards the head 9b than at the base of the stem 9a. The cavity 9c may extend into the head 9b of the push member 9, such that the cavity is longer than the stem 9a. The cavity 9c can also be of same length or essentially the same length of stem 9a. The cavity can also be shorter than stem 9a.

Furthermore, the stem 9a may comprise one or more opening(s) or aperture(s) 9d. Opening 9d can be arranged symmetrically, or asymmetrically. The shape of opening 9d can be round, elliptical, square, rectangular, or any combination of rounded and/or square features. Usually, the opening 9d is in fluid connection with the cavity 9c.

If there are more than one opening 9d in said shaft, they can be of identical or similar in size and/or shape, or they can also be different. Openings 9d can be arranged symmetrically on the shaft, such as rotationally or mirror symmetrically. They can also be arranged asymmetrically, and/or differ in size.

In some embodiments, the combined areas of said one or more openings 9d can also be rather large, such as around 20, 25, 30, 35, 40, 45, 50, 55 or 60% of the outer area of stem 9a.

In some embodiments, the combined areas of said one or more opening(s) 9d can be more than 20, 25, 30, 35, 40, 45, 50, 55 or 60% of the outer area of stem 9b.

Stem 9a may also be present only in part. As seen in the embodiment depicted in FIG. 4b, stem 9a is both reduced in length and only present in part. Here, around half of stem 9a is replaced by a single, large opening 9d. Stem 9a and opening 9d are depicted with straight, common edges. However, in some embodiments, said opening may comprise curved, symmetrical or asymmetric common edges. This is e.g. exemplified in FIG. 4c, where a push member 9 with a non-rotational sym- metric shaft and an opening 9d is shown with rounded edges, and said opening 9d extends from the end of the shaft 9a to the head 9b.

It is believed that said one or more opening(s) 9d improve the stability of the push member 9 during the injection moulding process, thereby providing one or more measurable process improvements. Said opening(s) 9d may e.g. provide a better integration of the push member 9 with the hollow shaft, such as a better integration with the massive end section 8, apart from a reduction in weight and/or material.

The head 9b of the push member 9 is designed to pushing molten polymer in front of the push member 9 on its path towards the upper end 12b, and deposing the polymer against the inner wall of the cavity 12, forming a hollow handle. Once the push member reaches the upper end 12b of the cavity, the molten polymer is compressed into a massive block that forms the massive end section 8 at the rear end part 2b of the handle 2. Suitably, head 9b can be shaped like a mushroom or bullet; however, other shapes may be suitable as well.

In some embodiments, head 9b comprises one or more indentation(s) 9g. Said indentations may provide a better integration of the push member 9 with the hol low shaft, such as a better integration with the massive end section 8. Said inden- tations may also provide reduction in weight and/or material. Said indentations can be symmetric, such as round or oval, or square and the like. They can also be asymmetric, e.g. as depicted in FIG.4c.

In some embodiments, the ratio of height of head 9b to diameter of head 9b is in the range of 3:1 to 1:3 in length. In some embodiments, said ratio is around 3:1, 2.5:1, 2:1, 1.5:1, 1.25:1, or 1:1. In some embodiments, said ratio is greater than

3:1, 2.5:1, 2:1, 1.5:1, 1.25:1, or 1:1. In some embodiments, said ratio is around 1:3, 1:2.5, 1: 2, 1:1.5, or 1.25:1. In some embodiments, said ratio is smaller than 1:3, 1:2.5, 1: 2, 1:1.5, 1.25:1, or 1:1. In some embodiments, the ratio of length of stem 9a to height of head 9b is in the range of 4:1 to 1:10 in length. In some embodiments, said ratio is around 4:1, 3:1, 2.5:1, 2:1, 1.5:1, 1.25:1, or 1:1. In some embodiments, said ratio is greater than 4:1, 3:1, 2.5:1, 2:1, 1.5:1, 1.25:1, or 1:1. In some embodiments, said ratio is around 1:10, 1:8 1:8, 1:7, 1:6, 1:5, 1:4, 1:3, 1:2.5, 1:2, 1:1.5, 1:1.25, or 1:1. In some embodiments, said ratio is smaller than 1:10, 1:8 1:8,

1:7, 1:6, 1:5, 1:4, 1:3, 1:2.5, 1:2, 1:1.5, 1:1.25, or 1:1.

For some applications, it has been found advantageous to use a push member 9 with a shorter shaft 9a. It is believed that a shorter shaft reduces the risk of un- desired "capsizing" of the push member 9 during the injection moulding process.

As illustrated in Figure 4, the push member 9 may comprise one or more further cavity(ies) 9e, providing a thinner outer wall of the head 9b. Said further cavity 9e can be arranged at the widest part of the head 9b. Apart from a reduction in weight and or material needed for the push member 9, said further cavity 9e may provide an improved integration of push member 9 with the hollow shaft/handle, such as with the compact end section 8. The present invention also concerns a mould for a push member 9 as disclosed herein.

Furthermore, the present invention also concerns a mould for an injection mould- ing method or process as disclosed herein. Commonly, said injection mould 1 comprises an injection moulding cavity 12 shaped as a template for the handle 2 in addition to a further injection moulding cavity 20 shaped as a template for the push member 9 for simultaneous moulding of a handle 2 and a push member 9. Alternatively, handle 2 and push member 9 can be provided using different moulds, either as part of the same moulding process or independently from each other.

The injection moulding process, according to the invention, can be horizontal in- jection moulding, or vertical injection moulding. In the case of vertical injection moulding, the push member can be provided at the lower end of the cavity 12. Alternatively, the push member could also be provided at the upper end of the cavity 12.

In summary, advantages of using push members as disclosed herein, such as il- lustrated in FIG. 2 and/or FIG. 4 in an injection moulding process may comprise one or more of: (i) more reliable, stable process; (ii) more uniform wall thickness; (iii) less waste through reduction of rejection rate; (iv) increased robustness and/or stability of the manufactured handle and/or shaft; (v) lighter shaft/handle; and or (vi) more compact end section.