A FLYWINDER

Abstract: In a rotatable flier (1) of the kind having a hollow interior which is a surface of rotation symmetrical about the axis of rotation of the flier and which is conical, said surface of rota­ tion increasing in diameter smoothly along its length from an axially directed filament inlet guide (8) closely circumscribing said axis, the greater diameter end of the hollow interior being adapted for disposition adjacent to a bobbin support (11) and being of diameter such that a bobbin (10) or like former mounted on the support (11) can be received therein, final filament guide means (9) being disposed at or adjacent to the greater diameter end and through which the filament is con­ strained to pass before being wound on the bobbin (10) or like former, the improvement comprising filament guide means (31) disposed in the hollow conical interior of the flier inter­ mediate the ends thereof to restrain the filament against cir­ cumferential movement relative to the interior surface of the flier during winding to reduce frictional forces acting on the filament particularly during high-speed coil winding.

Description: TITLE: A FLYWINDER DESCRIPTION TECHNICAL FIELD The invention relates to an apparatus and a method of winding filamentary material, particularly wire, on a bobbin. BACKGROUND ART A technique generally known as '1fly winding" is presently available for wrapping wire around a stationary bobbin and the technique has certain inherent advantages over wire wrapping systems in which the bobbin is rotated. Thus for example where a bobbin rotated at high speed centrifugal force tends to loosen the wire so that correct winding is rendered difficult or impossible. The device normally used for fly winding comprises a hollow shaft to which a cranked arm carrying wire guides is attached. A bobbin is placed inside the swing of the cranked arm and on the same axis as the shaft and wire is threaded through the shaft, around the wire guides of the cranked arm and is attached to the bobbin or to some point adjacent to it. Rotation of the shaft and the cranked arm while the bobbin is reciprocated axially wraps the wire around the bobbin and draws more wire over the guides and through the hollow shaft. This method involves a number of more or less sharp changes of direction for the wire which causes a drag effect similar to that produced when a rope is wrapped around a bollard for arresting the movement of a ship. This form of drag is called "bollard effect". The formula for "bollard" effect (the factor by which tension is multiplied as a result of directional change at a wire guide or bend in a guide tube) is eUg where u is the coefficient of friction and G8 the change of direction in radians. A typical cranked arm design will have four guides, one at each end of the hollow shaft and two on the cranked arm. The wire will make a 450 change of direction from the exit of the hollow shaft to the entry of the first guide, a further 450 change to bring it parallel to the rotational axis of the shaft and a final 900 change from the last wire guide onto the bobbin being wound, making a total of 1800 of "bollard" effect. This however is only true in static or slow winding conditions. When winding at high speed this is increased due to air resistance to the exposed length of wire being rotated and due to centripetal forces acting on the wire, causing it to take a non linear path between the guides. These effects are further increased when 'flap" develops due to small imperfections at the wire supply reel and due to inherent speed changes of the wire when winding rectangular bobbins. This flap produces additional and fluctuating "bollard effect11 at the entry to the wire guides in the system. This fluctuating bollard effect is particularly disadvantageous because it may make it impossible to achieve a satisfactory average level of tension without producing peaks of tension in excess of the breaking strain of the wire. One variation of the cranked arm design that has been tried in order to overcome air resistance effects and centripetal effects uses an 'S' shaped tube. This stabilises the wire path but suffers from the fact that wear and friction occurs at the bends in the tube due to the difficulty of achieving a polished, wear resistant surface inside a bent tube. The separate guides of the conventional cranked arm design do not suffer from this disadvantage because they can be made of very hard ceramic material such as aluminium oxide in the form of a radiused eyelet that can be polished with diamond paste before assembly in to the flier A cranked arm design with ceramic eyelets as described above but with tubes linking the ceramic guides would seem to overcome these problems but this suffers from difficulties of threading the wire when changing wire supplies. Also such a design retains the excessive 1800 bollard feature mentioned above. To reduce bollard effect we have previously proposed a fly winder having a rotatable hollow conical flier and a rotationally stationary bobbin support concentric with the hollow conical flier, the flier and bobbin support being axially reciprocable towards and away from one another, wherein the hollow conical interior of the flier is a surface of rotation symmetrical about the axis of rotation of the flier forming a filament guide surface adapted to restrain outward radial movement of the filament > said surface of rotation increasing in diameter substantially smoothly along its length from an axially directed filament inlet guide closely circumscribing said axis at substantially the apex of said surface of rotation, the greater diameter end of the hollow interior being disposed adjacent to the bobbin support and being of diameter such that a bobbin or like former mounted on the support can be received therein filament guide means being disposed at or adjacent to the greater diameter end and through which the filament is to be constrained to pass before being wound on the bobbin or like former with the filament having freedom of circumferential movement intermediate the filament inlet and the filament guide means. The conical hollow interior of the flier is arranged so that the wire enters the hollow interior substantially on the axis of rotation of the flier. In such an arrangement the wire on entering the flier is free to assume its own position in the wire guide, and it has been found in practice that the wire tends to assume a helical formation before passing through the final guide member, because in passing from the apex towards the rim of the cone, the rotational speed of the wire increases rapidly. Due to inertia the wire lags behind the rotating surface until the tension of the wire balances the lag forces. It was thought that the helix of wire would act as a reservoir which would absorb the fluctuations in feed rate demanded when winding rectangular bobbins and damp out small tension#increases which arise due to imperfections on the supply reel of wire. We have however discovered that particularly with increased winding speeds the benefit due to formation of the reservoir of wire is offset by the bollard effect still inherent in such an arrangement. We have identified one particular area for improvement as being the final wire guide since due to formation of the helix in the flier the wire changes direction through more than 900 at this point. DISCLOSURE OF INVENTION Accordingly the present invention is a rotatable flier having a hollow conical interior which is a surface of rotation symmetrical about the axis of rotation of the flier, said surface of rotation increasing in diameter smoothly along its length from an axially directed filament inlet guide closely circumscribing said axis, the greater diameter end of the hollow interior being adapted for disposition adjacent to the bobbin support and being of diameter such that a bobbin or like former mounted on the support can be received therein, final filament guide means being disposed at or adjacent to the greater diameter end and through which the filament is constrained to pass before being wound on the bobbin or like former, and comprising filament guide means disposed in the hollow conical interior of the flier intermediate the ends thereof to restrain the filament against circumferential movement relative to the interior surface of the flier during winding. The guide means may be a plurality of eyelets or other discrete guides spaced along the flier but is preferably in the form of a continuous member e.g. a flange or channel, extending along a substantial part of the conical interior surface of the flier. The guide means is preferably a tubular member supported along its length by the interior surface of the flier and through which the wire is constrained to pass. The tubular member is the preferred arrangement since it facilitates the initial threading of the filament through the flier. The tubular or other continuous member preferably extends from close to the inlet guide to the outlet guide. The tubular member may be of small diameter to avoid fouling a bobbin to be wound or alternatively the tubular member may be of somewhat larger diameter and of an oval rather than a circular cross-section to reduce its radial depth. The interior of the tube may be anodised to improve its resistance to wear. A larger diameter tube, e.g. 7 mm, is of advantage since the final filament guide can be in the form of an eyelet set directly into the end of the tube. The inlet end of the tube is preferably also provided with an eyelet. The eyelets are preferably ceramic. Advantageously the angle between the filament guide means and the axis of rotation of the flier is 140 plus or minus 10. The flier is itself preferably substantially conical in shape and is symmetrical about its axis of rotation to facilitate high speed operation by being of low mass and inherently good balance. BRIEF DESCRIPTION OF DRAWINGS In order to enable the invention to be more readily understood embodiments thereof will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a partly sectional view of an embodiment of an apparatus for fly-winding an electrical coil; Figure 2A is enlarged cross-sectional view of the flier; Figure 2B is a section on the line of Figure 2; Figure 2axis a view similar to that of Figure 2A of a modified flier; Figure 2D is a view similar to Figure 2A of a further embodiment of flier; Figure 3 is a cross-sectional side elevation of another embodiment of fly-winding apparatus; Figure 4 is a cross-sectional rear view of the apparatus of Figure 3; and Figure 5 is an enlarged cross-sectional side elevation of the apparatus of Figures 3 and 4. BEST MODE OF CARRYING OUT THE INVENTION In Figures 1 and 2 of the drawings an apparatus for winding an electrical coil comprises a hollow flier 1, one end 2 of which is supported by a pair of ball bearings generally indicated as 3 so that the flier is rotatable about its axis. The bearings 3 are of conventional construction and so are not described in detail. The flier 1 is generally frustoconical in shape and is formed at its said one end 2 with a generally cylindrical section 4 to facilitate the mounting thereof in the bearings 3. Internally the flier is formed with a substantially conical recess 5 extending through the flier from end to end so that the flier is a hollow thin-walled tubular member. A ceramic guide member or eyelet 8 is mounted to define the entrance to the small diameter end 6 of the conical recess. The conical recess 5 supports a tubular wire guide 31 which extends over a substantial axial distance in the recess 5 and which terminates at the open or wide end of the recess. The tube 31 is terminated at its inner end with a ceramic eyelet 29 and at its outer end with a ceramic eyelet 9. As can be seen in Figures 2A and 2B the tube 31 is oval in cross-section over most of its length to reduce as far as possible its radial dimension. Only the ends of the tube 31, where it carries the eyelets 9 and 29 are of circular cross-section. Figure 2C shows another embodiment in which the filament guide means in the interior of the flier consists of a rectilinear array of ceramic eyelets 29 spaced along the conical recess 5. In Figure 2D the flier is formed at its wide end with a short cylindrical section 51, to accommodate axially long bobbins. This arrangement minimises the diameter of the wide end of the flier in cases where long bobbins have to be wound. The wire is constrained to pass through the tube 31 or through the array of eyelets before it is wound on a bobbin, and in so doing the wire is constrained to follow a substantially straight path through the flier. In this way the bollard effect when the filament leaves the end of the tube is reduced. The conical flier functions to support the tube for rotation at high speed. The tube 31 may be secured in position in the conical flier in any convenient manner and may for example be secured by means of wire ties and/or by means of an adhesive such as an epoxy resin. The tube 31 is a thin walled tube preferably of aluminium and is preferably internally anodised to improve its wear resistance. A counter-balancing weight 30 is provided opposite the guide tube or alternatively a pair of guide tubes may be disposed diametrically opposite one another. The bobbin 10 is mounted on the end of a support shaft 11 which is arranged to reciprocate such that the bobbin moves between a position in which it is disposed wholly within the flier (as shown) and a position in which only the free end of the bobbin is within the conical flier. The means for rotating the flier and the means for reciprocating the shaft 11 will now be described. A transmission shaft 15 supported in bearings 16 is arranged to be driven by an electric motor (not shown). A toothed wheel 12 is fixedly secured on the shaft 15 between the bearings 16 and transmits the drive of the shaft 15 to the flier by means of a toothed belt 13 (shown in dash-dot lines) and a toothed drum 14 fixedly mounted on the flier 2. The drum is of sufficient length to accommodate two drive belts if desired. At the end of the shaft 15 remote from the flywheel is a wheel 17 connected by a belt 18 to a wheel 19 on the input shaft of a gearbox 20. Conveniently a worm-reduction gear is employed, e.g. having a reduction ratio of 40:1. A cam device may be incorporated for changing the reduction ratio. The output shaft of the gear box 20 drives a first toothed wheel 21, which meshes with a second toothed wheel 22, which in turn meshes with a third toothed wheel 23. The second and third toothed wheels 22 and 23 are associated with right-hand and left-hand clutches 24 and 25 respectively. The right-hand clutch is arranged to drive a pinion 26 and the left-hand clutch a pinion 27, both of which engage a rack 28 mounted on the shaft 11. It will be appreciated that when the right-hand clutch is engaged, the rack 28, and with it the shaft 11, are moved in one axial direction, and when the left-hand clutch is engaged the rack 28 and shaft 11 are moved in the opposite axial direction. In each case, the pinion 26 or 27 which is not engaged freewheels. Limit switches (not shown) are provided for limiting the traverse of the rack 28 by transmitting a signal effective for disengaging one clutch and engaging the other. Disengagement and engagement are effected by means of a pneumatic system which is shown in Figure 1 beneath the clutches. This system will not be described in detail because it is of conventional nature. It will be appreciated that in the aforedescribed apparatus the spted of rotation of the flier is proportional to the speed of reciprocation of the shaft 11. This is important in order that a uniform spacing is achieved between the turns of the coil being wound. When very high speeds are required, the electric motor may be replaced by a turbine. The embodiment of fly-winding apparatus of Figs. 3 to 5 is of the kind generally described above with the important difference that in the present case the fliers are axially reciprocatable and the bobbin supports are axially stationary. The fly winding apparatus comprises a stationary box-like frame 41 in which a carriage 32 is mounted for reciprocation on a parallel pair of cylindrical rods 36 and 37 respectively which are stationarily mounted in the frame 41. The carriage is mounted for reciprocation without play on sets of linear bearings 38 which engage the rod 36 and the carriage carries a pair of rollers or followers 39 which engage opposite sides of the rod 7. In this manner the carriage can be reciprocated without play in the stationary frame. Reciprocation of the carriage is controlled by means of a hydraulic ram 40 the cylinder of which is fixed to the stationary frame and the rod of which is fixed to the carriage. Four vertically superposed conical fliers 1 of the kind generally described above are carried by the carriage and are mounted in bearings 3 so that they may be driven in rotation about their axes. In this way it is possible to support the fliers for rotation at very high speed and at the same time to reciprocate the fliers relative to stationary bobbins 10 so that wire may be wound on the stationary bobbins. As is shown in Figures 4 and 5 of the drawings the stationary frame 41 carries a drive shaft 43 which is journalled in the frame for rotation about its axis but which is axially fixed. The drive shaft is formed with splines 50 which are engaged by correspondingly splined pulleys 44 and 45 respectively which are mounted in the carriage 32 so that the pulleys are fixed for rotation with the shaft 43 but are axially slidable thereon during reciprocation of the carriage. Each of the fliers 1 is formed with a corresponding pulley 14 and toothed belts 13 and 13' respectively are engaged with the respective pulleys such that the pulley 44 drives a belt 13 which is engaged with the uppermost and the lowermost of the pulleys 14 while the pulley 45 drives a belt 13' which engages the two intermediate pulleys 14. The belts are preferably toothed belts. The drive shaft 43 is rotated by an electric motor (not shown in the drawings) which is connected to the drive shaft by means of a flexible belt and through a drive pulley 57 mounted on the drive#shaft. The fliers are thus driven in rotation at high speed during reciprocation of the carriage. Wire guides 60 are mounted on the carriage 32 and are axially aligned with the fliers so that the wire to be wound on the bobbins may be guided from a reservoir through a stationary frame and to the inlet of the fliers 1. INDUSTRIAL APPLICABILITY Although the invention has been described both generally and particularly with reference to winding wire for an electrical coil, the invention can be used for winding other coils, and for winding threadlike elements other than wire.

Claims: CLAIMS 1. A rotatable flier having a hollow interior which is a surface of rotation symmetrical about the axis of rotation of the flier and which is conical over at least a major portion of its length, said surface of rotation increasing in diameter smoothly along at least a major portion of its length from an axially directed filament inlet guide closely circumscribing said axis, the greater diameter end of the hollow interior being adapted for disposition adjacent to the bobbin support and being of diameter such that a bobbin or like former mounted on the support can be received therein, final filament guide means being disposed at or adjacent to the greater diameter end and through which the filament is constrained to pass before being wound on the bobbin or like former, and characterised by filament guide means (29, 31) disposed in the hollow conical interior (5) of the flier (1) intermediate the ends thereof to restrain the filament against circumferential movement relative to the interior surface of the flier during winding. 2. A rotatable flier according to claim 1, wherein the guide means is a plurality of eyelets (29) or other discrete guides spaced along the hollow conical interior surface (5) of the flier (1) in a rectilinear array. 3. A rotatable flier according to claim 1, wherein the guide means in the form of a member (31) having a continuous substantially straight guide surface extending along a substantial part of the conical interior surface (5) of the flier (1). 4. A rotatable flier according to claim 3, wherein the guide means is a tubular member (31) supported along its length by the interior surface (5) of the flier (1) and through which the filament is constrained to pass. 5. A rotatable flier according to claim 3 or claim 4, wherein the continuous member (31) extends from close to the inlet guide (8) to the outlet guide (9). 6. A rotatable flier according to claim 4 or claim 5, wherein the tubular member (31) is of oval cross-section and is disposed with its minor axis extending radially with respect to the axis of rotation of the flier (1). 7 A rotatable flier according to claim 6, wherein the interior surface of the tubular member (31) is anodised to improve its resistance to wear. 8. A rotatable flier according to any one of claim 4 to 7, wherein the final filament guide (9) is in the form of an eyelet set directly into one end of the tubular member (31). 9. A rotatable flier according to any of claims 4 to 8, wherein the inlet end of the tubular member (31) is provided with an eyelet (29). 10. A rotatable flier according to any preceding claim, wherein the angle between the filament guide means (29, 31) and the axis of rotation of the flier is 140 + 10.

Inventors: HADFIELD, RICHARD MCLAREN
Applicants: ROTAWINDER LIMITED
Application year: 1981
Main classification: B65H57
IPC codes: B65H57, H01F41, B65H54