Spool fixation device with bi-stable magnet assemblies

Abstract

A spool fixation device for use in a wire winding installation, where in this spool fixation device, spools having a magnetically attractable flange are held to a rotatable flange using magnet assemblies. The magnet assemblies can be switched between a hold state and a release state. In a preferred embodiment the magnet assemblies only consume energy when in the release state i.e. when the spool fixation device is not rotating. Alternatively the magnet assemblies can be made to only consume energy when switching states. The magnet assemblies have permanent magnet arrays and are moveable inside a non-magnetic housing. Also a drive pin to transfer torque between rotatable flange and spool is no longer necessary. Therefore the spool fixation devices allows for a smooth changeover of spools.

Claims

1. A spool fixation device for use in a wire winding installation comprising a rotatable flange for holding a spool with a spool flange that is magnetically attractable, said rotatable flange being provided with one or more magnet assemblies wherein said magnet assemblies are attached directionally compliant to said rotatable flange, wherein said one or more magnet assemblies is able to be selectively set to a hold state for magnetically holding said spool flange to said rotatable flange or to a release state for releasing said spool flange from said rotatable flange and wherein said magnet assemblies comprise permanent magnet arrays that are sealed from the outside by a housing, wherein said magnet assemblies require energy input when in the release state or wherein said magnet assemblies require energy input when switching state, wherein said spool fixation device further comprises an energy coupling for coupling said energy input from the wire winding installation to said magnet assembly, wherein said energy coupling is able to be established when said spool fixation device is stationary and wherein said energy coupling is able to be broken when said spool fixation device is rotating.

2. The spool fixation device according to claim 1, wherein said energy input is one or two out of the group comprising electrical, pneumatical, or mechanical energy.

3. The spool fixation device according to claim 1, wherein said permanent magnet arrays are alternatingly moveable in said magnet assemblies from a close position for strong attraction of the spool flange in said hold state to a remote position for weak attraction to the spool flange in said release state.

4. The spool fixation device according to claim 1 further comprising a magnetic shunt, wherein said permanent magnet arrays and said magnetic shunt are relatively and alternatingly moveable in said magnet assemblies from a shunt configuration, wherein said permanent magnet arrays' field is shunted in said release state to a coupling configuration, wherein the permanent magnet's field is not shunted in said hold state.

5. The spool fixation device according to claim 1, wherein said magnet assemblies further comprise a high-friction layer at least at the surface intended to contact the spool flange.

6. The spool fixation device according to claim 1, wherein said rotatable flange is further provided with a centering pin for centering the spool to be held.

7. The spool fixation device according to claim 6, wherein the length of said centering pin is equal or larger than the width of the spool to be held.

8. The spool fixation device according to claim 6, wherein the length of said centering pin is shorter than the width of the spool to be held.

9. The spool fixation device according to claim 1, wherein said energy coupling is able to be established or able to be broken by the same type of energy as the energy input to the magnet assemblies.

10. The spool fixation device according to claim 9, wherein said energy coupling is able to be established or is able to be broken by the same energy input as the energy input to the magnet assemblies.

11. The spool fixation device according to claim 1, wherein said energy coupling is a rotatable energy coupling.

12. A wire winding installation provided with at least one spool fixation device according to claim 1.

13. The wire winding installation according to claim 12, suitable for winding spools with steel wire, said full winding spools having a mass of more than 100 kg.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows the spool fixation device in perspective view.

(2) FIG. 2 is a cross-sectional view of a first embodiment of a magnet assembly.

(3) FIG. 3 is a cross-sectional view of a second embodiment of a magnet assembly.

(4) FIGS. 4a and 4b are cross-sectional views of a third embodiment of an exemplary magnet assembly.

(5) FIGS. 5a and 5b are axial cross sections of an embodiment of the energy coupling.

(6) FIG. 6 shows a spool that is specifically designed for use with an embodiment of the spool fixation device.

(7) The first digit in the reference in the numbers refers to the figure number. In FIGS. 2 to 4 equal tens and unit numbers refer to equal or similar items.

DETAILED DESCRIPTION OF THE INVENTION

(8) A perspective view of the spool fixation device is shown in FIG. 1. Basically the device comprises a rotatable flange 102 on which magnet assemblies 104, 104, 104, 104 are mounted. The magnet assemblies slightly protrude above the plane of the rotatable flange 102. As known in the art the rotatable flange is mounted fixedly to a co-rotating axis 106. A centering pin 108 is mounted centrally to centre the spool on the spool fixation device. The centering pin 108 protrudes from the rotatable flange 102 with a length L. An energy coupling 110 is provided at the end of the axis 106. The spool fixation device is mounted by the axis 106 in a wire winding installation (not shown) such as a winding bench for 12 or 24 or more spools. The full spools in this kind of installation have a mass of more than 100 kilogram. Note that no drive pin to transfer torque to the spool is present on the rotatable flange 102 as in prior art installations.

(9) The centering pin 108 does not have to extend through the complete bore hole of the spool. When the width of the spool is larger than the length L of the centering pin, the spool is partly carried by the centering pin and partly by the rotatable flange 102 in contrast with prior art installations where the full weight of the spool is carried by the cantilever shafts. Nevertheless the use of a centering pin that extends through the bore hole of the spool i.e. protrudes at the spool flange opposite to the rotatable flange 102 remains possible. In that case the length L of the centering pin is larger than the width of the spool.

(10) FIG. 2 shows a first embodiment of the magnet assembly 200. The magnet assembly is held in a round box 218 that is fixedly mounted on the rotatable flange 220 by means of bolt 222. The non-magnetic housing consists of a cylindrical body 206 of aluminium with a front cover 204 made of brass. The back cover 208 is made of magnetisable ferritic or martensitic stainless steel. The housing seals the internal permanent magnet array 203 from the outside environment. The magnet array 203 comprises six permanent magnets 202, 202, 202 (other magnets are not shown) arranged in a hexagon and held in a polymeric holder made of cast resin. The permanent magnet's field are arranged alternating between adjacent magnets. The permanent magnets are by preference Hicorex?, high performance magnets of the NdFeB type obtainable from Hitachi Magnetics corporation.

(11) The permanent magnet array 203 can move from a position close to the front cover 204, to a position remote from the front cover indicated with a light dashed line 203 in FIG. 2. To this end the round permanent magnet array 203 is provided with a pair of circumferential sealing rings 224, 224. The seal rings are by preference high elastic and wear resistant Viton? seal rings. By pressurising the air input 216 the magnet array is pneumatically pushed from the position close to the spool to a position 203 more remote from it. In order to allow the pressure to spread between magnet array and front plate 204 the front plate or the magnet array may have cut-in channels.

(12) The magnet assembly is mounted directionally compliant in the box 218. This is achieved by a spring 210 and bolt 212 mount. In this way the magnet assembly can swivel inside the box 218 but cannot be pulled out as the bolt 212 prevents this.

(13) Once the magnet array has reached the remote position 203, the air pressure can be released as the magnet array is now slightly attracted by the weakly magnetisable back cover 208. When all the magnet arrays in the respective magnet assemblies 104, 104, 104 and 104 are in the remote position i.e. the release state, the spool can be removed from the spool fixation device as the flange of the spool is released from the rotatable flange 220, 102.

(14) When now an empty spool has been slid over the centre pin 108, the magnet assemblies can be set to the hold state by air pressurising line 214. The magnet array is then moved from the remote position 203 to the close position 203 thereby holding the flange of the spool magnetically. Once the spool flange is attracted by the magnet arrays, the air pressure can be removed and the spool may start turning without any further energy input to the magnet assemblies. This is one of the major advantages of this spool fixation device: there is no need for an energy input to hold the spool during operation. Another advantage of this embodiment is that only an air pulse is needed when changing state.

(15) In order to increase the shear force resistance of the spool flange relative to the magnet assembly during winding, the front cover 204 is provided with a vulcanised rubber layer 226. This rubber layer adheres very well to the brass front cover 204. By preference it is less than 1 mm thick in order not to weaken the magnetic attraction.

(16) Another advantageous embodiment of the magnet assembly 300 is shown in FIG. 3. In this embodiment the back cover 308 is made of aluminium. The directional compliance is achieved through a resilient collar 310made of rubber and a ball bolt 312. Analogously with the previous embodiment, the magnet array 303 is composed of six permanent magnets with alternating polarity. Now line 314 centrally feeds pressurised air through centre tube 316 to between the front cover 304 and permanent magnet array 303. Sliding seals 324, 324 , 324, and 324 ensure sealing. When now pressurised air is supplied through line 314 the magnet array will move away from the position close to the spool. A conic spring 315 pushes the magnet array back, but the force of the spring is overcome by the force exerted by the pressurised air.

(17) As long as the pressure remains on, the magnet array 303 remains in remote position i.e. the release state. As soon as the pressure disappears, the magnet array moves to the hold state under action of the spring 314. There are therefore two different kinds of energy input: mechanical (the spring) and pneumatical. The advantage of this embodiment is that only one air feed line 314 is needed. On the other hand pneumatic energy is needed as long as the magnet array is in the release state. However, normally this will not take long as the time needed to remove or mount a spool is relatively short. In between removing and mounting a spool the pressure can be released.

(18) A further embodiment of a magnet assembly is shown in FIGS. 4a and FIG. 4b that is a cross section through plane AA of FIG. 4a. Again the assembly is mounted directionally compliant in box 418 through ball bolt 412. But now the four magnets 402, 402, 402 and 402 remain stationary in the assembly. A shunt 430 made of a ferromagnetic material such as iron is mounted between front cover 404 and the permanent magnets. The segmented shunt 430 can turn in front of the poles of the permanent magnets by turning axis 414. Friction between magnets 402, 402, 402, 402 as the magnets strongly attract the shunt 430is diminished by putting a low friction layer 432such as Teflon? film-between magnets and shunt. Switching states is now realised by turning axis 414 (mechanical energy input). When the shunt 430 is turned in front of the magnets, the magnetic field is diverted through the shunt 430 and considerably weakened near the spool flange. Clearing the magnets from the shunt will enable the magnetic field to attract the spool again.

(19) A convenient pneumatic energy coupling 110 between the wire winding installation and the spool fixation device is shown in FIG. 5a in the open state (for example during rotation of the axis 106) and in FIG. 5b in the closed state (when the axis 106 is stationary). The coupling is specifically convenient to cooperate with the magnet assemblies of the second embodiment (FIG. 3).

(20) During the operation of the installation, the magnet assemblies do not need energy and no pneumatic input is needed through feed tube 514. Then axis 502corresponding to axis 106 in FIG. 1is turning while the coupling housing 504 remains stationary attached to the wire winding installation. Housing 504 and axis 502 are centred to one another through ball bearing 506.

(21) The coupling is provided with a piston 516 axially moving on feed tube 514 in housing 504 and sealed by means of seals 518 and 518. The piston pushes against elastomeric expandable seals 510, 510 that are held by the centre bored nut 508 that is threated on the feed tube 514. Elastomeric expandable seal 510 is attached to piston 516. The inner seals 520, 520 must therefore not be of high quality or can even be replaced with circlip rings.

(22) When now the axis 106/502 has come to standstill and a spool is to be removed or loaded, the pressure chamber 530 is charged with pressurised air through inlet 512 as shown in FIG. 5b. The piston 516 compresses the elastomeric expandable seals 510, 510 that thereby radially expand and provide a seal between the hollow axis 502 and the feed tube 514. Now compressed air can be fed through feed tube 514 that on its turn will put the magnet assemblies 104, 104, 104 and 104 in the release state. A split tree is provided in the axis 106 to feed all magnet assemblies at the same time.

(23) When the magnet assemblies are to be put in the hold state the pressure on feed tube 514 is released. Thereafter air is released from pressure chamber 530 and the elastomeric expandable seals push back piston 516 into the open position. The pneumatic coupling between rotatable axis 502/106 is now removed and the axis can freely turn. In this way the use of a rotatable seali.e. a seal between coaxial axes freely rotating relative to one anothercan be prevented. Rotatable seals are maintenance intensive and prone to wear.

(24) The operation cycle can further be simplified by using appropriate differential valves between inlets 514 and 512 and the pneumatic air supply such that the whole cycle can be completed from one source.

(25) FIG. 6 shows a spool that is specifically adapted for use with the spool fixation devices as explained here before. The spool 600 is made of steel sheet of 4 mm thick. As usual ribs 604 are stamped in the metal sheet to reinforce the flange. It is therefore that the magnet assemblies 104, 104, 104, and 104 are protruding out of the plane of the rotatable flange 102 in order not to be hampered by the ribs. It goes without saying that the symmetry of the reinforcement ribs 604 (in this case 8-fold) must be compatible with the symmetry of the magnet assemblies (in this case 4-fold). Between the ribs the flat sectors that may come in contact with the magnet assemblies are provided with an anti-slip coating 610. If the magnet assemblies are provided with a rubber cover a suitable anti-slip coating may be a rough or serrated coating such as for example obtained by coating with a sand containing paint. When using such spool there is no need to align a drive hole with a drive pin which greatly simplifies the mounting of the spool.