1, Field of the Invention THIS INVENTION relates to a method of, and apparatus for, manufacturing a coiled sheath for electrical cords. (The term "electrical cords" shall include electrical appliance cords, electrical extension cords or leads, electronic communication cords or the like.)

2. Prior Art

Electrical cords cause a number of problems. In use, cords are generally longer than the distance between the power outlet and the appliance (e.g. electric jug, toaster and iron) and so must be draped or pushed out of the way on the bench. When not in use, they are untidy and difficult to store.

In our earlier International Application No PCT/AU91/00356 (International Publication No WO92/03368), there is disclosed a coiled sheath which may be fitted to such cords, and a method for manufacturing same. The method disclosed therein, while producing coiled sheaths which are highly suitable for their intended purpose, is largely manual in nature and is not suitable for the production of coiled sheaths on a large scale, commercial basis.

SUMMARY OF THE PRESENT INVENTION It is an object of the present invention to provide a simple, efficient means to manufacture coiled sheaths for electrical cords.

It is a preferred object to provide such a method where the resultant sheaths are coiled for easy storage but can be easily extended to the full length in use. It is a further preferred object to provide a simple, efficient apparatus to effect the method.

Other preferred objects will become apparent from the following description.

In one aspect, the present invention resides in a method for manufacturing a coiled sheath for electrical cords (as hereinbefore defined) including the steps of: withdrawing a tubular body, of resiliently flexible material, from a supply; drawing the tubular body through a heated bath, which is at a temperature above the forming temperature of the material; forming a slit in the tubular body before or after the tubular body passes through the heated bath; inserting a continuous core into the tubular body; winding the tubular body (and the core) about a mandrel or guide means to form the coiled sheath; cooling the coiled sheath below the forming temperature of the material; and stripping the core from the sheath.

Preferably the tubular body is formed of plastics material (e.g. of the type used to produce the standard outer sheath on appliance cords e.g. polyethylene) and preferably the body is formed with the spiral or coiled configuration along its length.

Preferably the slit is formed in the tubular body by drawing the tubular body past a knife or rotary cutter. Preferably the tubular body is formed of polyethylene and is drawn through a bath of viscous liquid e.g. glycerine at a temperature greater than 110°C after the slit has been formed in the tubular body. Preferably to insert the core into the tubular body, a core guide has a nose with outwardly divergent

trailing wings and the core, which is continuous, is fed into the body through the open slit.

Preferably the tubular body and inserted core are passed around three or more turns of a mandrel or guide means which defines a helical or spiral path. The mandrel may include a coil-spring like guide member surrounding a rotating shaft, the tubular body being drawn around the mandrel or guide means by the core and by frictional engagement with the shaft. Preferably the mandrel or guide means is provided in a bath of cold liquid e.g. iced water to assist in the cooling of the tubular body.

Preferably after the core is stripped from the cooled coiled sheath, the direction of the coiling of the sheath is reversed to increase its "springiness" i.e. its tendency to return to the coiled position. Preferably the sheath is cut to length. In a second aspect, the present invention provides apparatus for the manufacture of a coiled sheath for electrical cords (as hereinbefore defined) including: means to draw a tubular body, of resiliently flexible material, from a supply through a heated bath, which is at a temperature above the forming temperature of the material; means to form a slit in the tubular body; means to insert a continuous core into the body; means to draw or pass the tubular body (and inserted core) around a mandrel or guide means to form the coiled sheath; means to cool the coiled sheath below the forming temperature of the material; and means to strip the core from the sheath. Preferably the tubular body is drawn from a supply wound on a drum or supply coil.

Preferably the heated bath contains a viscous liquid e.g. glycerine at a temperature e.g. above 110°C.

The means to form the slit may comprise a knife or a rotary cutter. Preferably a core guide has a nose inserted into the end of the tubular body with divergent wings which cause the longitudinal slit in the body to be opened. Preferably the core, which is continuous, is guided into the slit by a guide pulley or roller and the core assists in drawing the tubular body from the supply (and through the heater) and in drawing the body about the mandrel or guide means.

The mandrel or guide means, to coil the body into the sheath, preferably includes a "spring", in the form of a hollow spiral, with a shaft rotating within it and the sheath is fed around the mandrel or guide means by the core and by frictional engagement with the shaft.

Preferably the core is stripped from the sheath after at least three turns around the mandrel but the sheath is preferably drawn around at least one further turn to assist coiling of the sheath.

Preferably at least the lower portion of the mandrel or guide means extends into a bath of cold liquid e.g. iced water which is preferably recirculated and cooled.

Preferably the sheath is caused to wind in the opposite direction from its winding on the mandrel or guide means and is supported on a frame which guides it past a docking or guillotine knife, which is preferably mounted on a pneumatic ram and is controlled by a timer mechanism to cut the coiled sheath to preset lengths.

BRIEF DESCRIPTION OF THE DRAWINGS

To enable the invention to be fully understood, a preferred embodiment will now be described with reference to the accompanying drawings, in which:

Fig. 1 is an isometric view showing the

resultant sheath fitted to a toaster cord (or lead) and on an extrusion cord (or lead);

Fig. 2 is a side perspective view of the sheath; Fig. 3 is an isometric view showing the sheath being fitted to an electrical cord;

Fig. 4 is a schematic view of the method of producing the coiled sheath;

Fig. 5 is a front view of the coiling machine; Fig. 6 is a top plan view of the machine;

Fig. 7 is a schematic side view of the slitting knife and core guide;

Fig. 8 is a side view of the timer mechanism for the guillotine knife; and Fig. 8A shows the timer mechanism of Fig. 8 in the "tripped" position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to Fig. 1, the sheath 10 is shown fitted to an electric toaster cord 11 and an extension lead 12, the plugs 13, 14 of which are plugged into a general power outlet (GPO) 15.

Referring to Fig. 2, the sheath 10 has a resiliently flexible plastics tubular body 16, wound into a spiral or coiled configuration, with an elongate slit 17 about its outer periphery. (As shown in Fig. 1, the toaster cord 11 and extension lead 12 are visible through the slit 17.)

To install the sheath 10, one end is placed adjacent the plug 13, 14 (or socket) of the toaster cord 11 or extension lead 12 and the slit 17 is opened to enable the cord or lead to be received with the tubular body 16. The slit 17 is progressively opened along the body 16, the cord or lead inserted, and the slit 17 partially closed about the cord or lead as it is progressively enclosed within the sheath 10.

The sheath 10 causes the cord 11 or lead 12 to

adopt its spiral or coiled configuration (see Fig. 1) but enables them to be stretched to their full suable length when required. The result is a tidy, compact cord or lead with a pleasing aesthetic appeal. To prevent the slit 17 from opening and releasing the cord 11 or lead 12 from the end(s) of the sheath 10, clips or ties (not shown) may be provided about the sheath, e.g. 1-2 cm from the end.

Referring now to Fig. 4, the method of manufacturing the sheath 10 will now be described briefly.

The sheath 10, formed from polyethylene tube, is drawn from a supply roll 20.

The sheath is drawn through a bath of glycerine 21 at e.g. 125°C (i.e. above the forming temperature of polyethylene which is approximately

110°C) so that the sheath becomes stretchable but its cylindrical shape does not collapse.

The sheath is drawn past a knife 22 which forms the slit 17 in the sheath

The heated sheath 10 is fed through past a core guide 23 in which a core 24 (e.g. a continuous length of polyethylene or polyurethane cable) on a convergent path is inserted into the sheath 10 and the combination is wound onto a mandrel 25.

The sheath 10 cools below the forming temperature in the ice water bath 26 about and takes up the coiled shape generated by the mandrel 25. The core

24 is stripped from the sheath 10, which is cut to length by a knife 27.

Referring now to Figs. 5 to 8A, the sheath 10 is drawn from the bath 21 past the core guide 23 which has a guide rod 30 inserted into the interior of the sheath 10 and a slitting blade 22 forms an elongate slit 17 in the sheath.

The core guide 23 is of U-shape at its

downstream end, with a pair of divergent wings 31 which cause the slit 17 to be opened to receive the continuous core 24 guided into the sheath by a guide pulley 32 which is freely mounted on a drive shaft 33 journalled in bearings 34, 35 on the frame of the machine.

An electric motor 36, with variable drive belt-pulley arrangement 37, drives a reduction gearbox 38 which drives the drive shaft 33 through a belt- and- pulley drive 39. The sheath 10, and inserted core 24, are drawn around a mandrel 25. The mandrel has a rotating shaft 40 rotating within a fixed "spring" or helical guide 41, the shaft 40 being driven from the drive shaft 33 via a suitable gear drive assembly 42. At least the lower portion of the mandrel lies within a bath 26 through which iced water is circulated to cool the sheath 10 (and core 24).

After the sheath and core have been drawn about three turns of the mandrel 40, and the sheath 10 has begun to cool, the core 24 is stripped from the sheath 10 by passing over a stripping pulley 44 which is in driving arrangement with the drive shaft 33. (The core 24 being drawn by the pulley 44, and the frictional engagement of the sheath 10 with the shaft 40 in the mandrel 25, draws the sheath 10 through the mandrel.)

The core 24 passes around a fixed idler pulley 45 and an adjustable idler pulley 46 and returns to the guide pulley 32. The adjustable idler pulley 46 is mounted on an arm 47 on a block 48 slidably mounted on the frame and is provided with a spring 49 and adjustment screw 50 to enable the tension on the core 24 to be set and maintained.

After the core 24 has been stripped from the sheath, the sheath passes around the mandrel 25 for a further turn.

A knurled brass wheel 50, mounted on a shaft

51 and driven from the drive shaft 33 via a belt and pulley drive 52, enters the slit 17 and assists in guiding the coiled sheath 10 from the mandrel. The sheath is caused to wind in the opposite direction (to its winding on the mandrel) as it is drawn from the mandrel 25 as it is found that this imparts a tension in the sheath which encourages it to return to a tightly coiled configuration when stretched.

The now coiled sheath 10 is supported on a horizontal support 53 and is fed past a guillotine knife 27. The knife 27 has a cutting blade 54 mounted on the piston rod 55 of a pneumatic ram 56. The sheath 10 is passed through a hole in a fixed anvil 57 to enable the sheath 10 to be docked to length e.g. after every six turns.

Referring to Fig. 8 and 8A, the pneumatic ram 56 is controlled by a timing mechanism 58 which controls the supply of compressed air to the ram via lines 59, 60. The timing mechanism 58 has a drive gear 61 on the shaft 40 and a driven gear 62 on an axle 63, the gears being connected by a chain 64. The chain 64 has a pin or finger 65 which engages a roller 66 on a pivotal arm 67. When the finger 65 engages the roller 66, it causes the arm 67 to pivot (see Fig. 8A) so that an extension 68 engages a pneumatic control valve 69 which causes the ram 56 to be extended, and then retracted, so that the knife blade 54 moves over the anvil 57 to cut the sheath. (For longer sheaths, the timing mechanism 58 may be disabled and the valve 69 operated manually. )

Alternatively, an electronic time unit may be used e.g. which counts the revolutions of the drive shaft 33. As the guide pulley 32 is free wheeling and self-locating on the drive shaft 33, the core 24 will

always be accurately fed into the sheath.

As will be readily apparent to the skilled addressee, the present invention provides a simple method/apparatus combination for the production of the coiled sheaths.

Various changes may be made to the embodiment described without departing from the scope of the present invention defined in the appended claims.