EP1355329A1

EP1355329A1 - Production of security pedestals

Info

Publication number: EP1355329A1
Application number: EP02394039A
Authority: EP
Inventors: Richard Patrick Guilfoyle
Original assignee: Sensormatic R&D Ltd
Current assignee: Sensormatic R&D Ltd
Priority date: 2002-04-17
Filing date: 2002-04-17
Publication date: 2003-10-22

Abstract

An apparatus (1) winds wire (6) onto one selected from a number of mandrels (50) having the configuration of a receive coil or a transmit coil for a security pedestal (80). Uniform tension to allow effective bonding after winding is ensured by a pre-tensioner (10) and a primary tensioner (20). An alignment mechanism (30) aligns the wire (6) to transverse extremities for first and second coil layers, and subsequently to a central position. A crimping device (32) forms a bend in the wire as an integral part of the winding operation. Kinking is avoided by drawings the wire (6) upwardly in the axial direction of a reel (3) and through the pre-tensioner (10).

Description

Introduction

The invention relates to production of security pedestals of the type comprising a frame supporting transmit and receive coils.
In such pedestals, the transmit coil transmits radiation at a pre-set frequency. If a surveillance tag enters the electromagnetic field a resonator element in the tag vibrates and changes the frequency of the radiation picked up by the receive coil in the pedestal. Such pedestals and surveillance tags have been marketed for some years by Sensormatic Corp.
Production of such pedestals requires great care to ensure that:
there is uniformity in spacing and orientation of the coil wire, and high-integrity bonding of conductors in the coils together, and
winding of the coil is performed in a safe manner for operators.
Heretofore, production of pedestals has been largely manual to ensure that the above criteria are met.
It is therefore an object of the invention to provide for increased automation while adhering to or improving the above quality and safety requirements.

Statements of Invention

According to the invention, there is provided an apparatus for producing coils of bondable wire for a security pedestal, the apparatus comprising:-
a drum for housing a wire reel, said drum comprising a lower reel-supporting base and an upper eyelet for guiding wire as it is drawn from a reel;
a pre-tensioner mounted downstream of the drum and comprising means for pre-tensioning wire as it is drawn from a reel;
a primary tensioner mounted downstream of the pre-tensioner and comprising means for applying additional tension to wire drawn through the primary tensioner;
an alignment mechanism mounted downstream of the primary tensioner, the alignment mechanism being mounted on a traverse unit comprising drive means for moving the alignment mechanism in a transverse direction with respect to wire travel to a desired transverse position;
a mandrel hub and associated drive mounted in a protective housing connected to the traverse unit, said mandrel hub comprising means for supporting a mandrel chosen from a range of different mandrel types; and
control means for causing the traverse unit to move to a selected transverse position for alignment of wire, and for causing the mandrel hub to rotate at a speed chosen according to the configuration of a mandrel mounted on the
hub and to draw wire from the reel at a desired speed.
In one embodiment, the apparatus comprises a crimping device mounted in the alignment mechanism.
In another embodiment, the alignment mechanism comprises at least two alignment wheels, and the crimping device is mounted between said alignment wheels.
In a further embodiment, the crimping device comprises a pair of opposed crimping jaws configured to bend the wire.
In one embodiment, the control means comprises means for moving the traverse unit to one transverse extremity for a first layer of windings on a mandrel, to an opposite transverse extremity for the second layer of windings, and to a central position between said extremities for subsequent layers.
In another embodiment, the feed drum eyelet comprises a lining of ceramic material.
In a further embodiment, the eyelet is mounted in a cross-bar extending across and above the reel-supporting base.
In one embodiment, the primary tensioner comprises a wheel having a rim groove for receiving wire wound around the wheel, and means for adjusting wheel rotational resistance.
In another embodiment, said adjustment means comprises an axial brake and means for adjusting brake pressure.
In a further embodiment, said adjustment means comprises a wheel and belt assembly and a bias means pressing said assembly against the rim of the wheel.
According to another aspect, the invention provides a method of producing a security pedestal, the method comprising the steps of:
connecting wire of the type having a bondable cement outer cladding to a mandrel, and rotating the mandrel to draw the wire from a reel in the axial direction of the reel through an eyelet, and through:
a pre-tensioner at which initial tension is applied to the wire,
a primary tensioner at which a selected primary tension is applied, and
an alignment mechanism,
moving the alignment mechanism in a direction transverse to the wire travel to a desired position for each layer of wire wound onto the mandrel,
forming a bend in the wire as it travels through the alignment mechanism,
cutting the wire when sufficient wire has been wound onto the mandrel,
directing electrical current through the wire to cause the cement to bond until the coil is a unitary structure, and
mounting the coil in a pedestal frame, and soldering a circuit connector to the coil at the bend in the wire.

Detailed Description of the Invention

The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only with reference to the accompanying drawings in which:-
Fig. 1 is a perspective view of a coil winding apparatus of the invention;
Fig. 2 is a diagrammatic side view of the apparatus;
Fig. 3 is a diagrammatic end view of a mandrel housing of the apparatus;
Fig. 4(a) is a diagrammatic cross-sectional view showing a pattern for winding wire onto a mandrel, and Fig. 4(b) is an end view of a mandrel support hub;
Fig. 5 is a diagrammatic end view of a wound coil showing a solder joint to a cable; and
Fig. 6 is a front end view of a pedestal housing.
Referring to the drawings an apparatus 1 for winding coils for production of security pedestals is illustrated. The coils are formed from wire comprising a copper core, an insulation cladding, and an outer layer of bondable cement. The apparatus 1 draws such wire from a reel and winds it onto a mandrel which is shaped to suit a particular type of pedestal. Current is then passed through the wire to cause it to heat, thus melting the bondable cement sufficiently to cause the wire coils to bond together as a unitary structure.
The apparatus 1 comprises an open-topped drum 2 for containing a raw material reel 3 of wire 6. The drum 2 comprises a cross bar 7 supporting an eyelet 4 of ceramic material.
A pre-tensionser 10 is mounted directly over the drum 2. The pre-tensioner 10 comprises a pair of rollers 11 and 12, each having a groove so that together the wheels form a closed channel for the wire 6 to run through. The sizes of the grooves are such that the rollers 11 and 12 impart an initial degree of tension and ensure that the wire 6 does not become kinked. Kinking is avoided because of the tension applied and because the wire 6 is drawn directly upwardly from the reel 3 along the reel's axis before being drawn horizontally.
A primary tensioner 20 comprises a wheel 21 around which the wire 6 is wound if additional tension is required (depending on the gauge of wire). An adjustment assembly 22 comprises three small wheels around which a belt runs, the whole assembly 22 being biased downwardly against the wheel 21 with a pressure chosen according to the tension required. Also, tension of the primary tensioner 20 can be set by adjusting friction between a brake disc 23 and the wheel 21. This is achieved by turning a handle 24 to change pressure applied to the brake 23 by a helical spring 25. The wire 6 is guided by ceramic eyelets 26 at entry to and exit from the wheel 21.
An alignment mechanism 30 comprising a first aligner 31, a crimping device 32, and a second aligner 33 is mounted after the primary tensioner 20. Each aligner 31 and 33 comprises a wheel 35 and a felt pad 36 mounted across the wheel 35 to press the wire 6 against the wheel rim. The felt pad 36 is supported on radial arms 37. The crimping device 32 comprises a pair of jaws which are pneumatically operated to clamp the wire 6 between them to form a crimp according to the desired crimp angle for later soldering of connectors to a pedestal circuit, as illustrated in Fig. 5.
The second aligner 33 delivers the wire 6 to a mandrel 50 which is rotated in a protective housing 40.
Referring to Fig. 3 the alignment mechanism 30 is secured to a traverse unit 42 on an end wall 41 of the housing 40. The unit 42 is mounted on two horizontal rails 43 by engagement of wheels 45 in the rails 43. A stepper motor and a ball screw mechanism move the traverse unit 42 horizontally in a lateral direction as indicated by the arrows of Fig. 3.
Referring to Figs. 4(a) and 4(b), a mandrel hub 55 has two studs 56 for supporting a range of different mandrels including the mandrel 50. The mandrel 50 is retained by wing nuts 57. The hub 55 does not move in its axial direction. However by movement of the traverse unit 42 left and right as viewed in Fig. 3 the wire 6 is wound onto the mandrel 50 as follows:-

for an innermost layer, the traverse unit 42 moves to a right-most extremity, whereby the wire (6(a)) of the first turn is against the right-hand mandrel flange and successive turns press in this direction,
for a next layer the traverse unit 42 moves to a left-most extremity, whereby the wire (6(b)) of the first turn is against the left-hand mandrel flange and successive turns press in this direction, and
subsequent layers are wound with the traverse unit 42 at a central location between these extremities.

It has been found that this arrangement provides for uniform and stable winding patterns, the first and second layers providing a stable and balanced foundation for the turns.
After winding onto the mandrel 50, the wire 6 is heated by application of voltage, thus causing it to bond together into a unitary coil structure. The coil is then removed from the mandrel 50 and it is placed in a frame 81 to provide a pedestal 80. The frame 81 comprises an inner annular housing 82 for a receive coil, and an outer annular housing 83 for a transmit coil. Thus, a single pedestal product requires two different winding operations with different mandrels.
Connection to circuits of the pedestal are made by forming a bend 71 in the wire 6 using the crimping device 32 during coil winding, and subsequently soldering flexible wires 72 of the circuit at the bend 71 as shown in Fig. 5. Because the kink is formed as in integral part of the winding operation, there is no need to subsequently disturb coils after winding or after bonding. This is important for stability of the coil.
It will be appreciated that the apparatus 1 achieves a consistent tension of wire feed in a repeatable manner. This is very important as it avoids kinks which would affect quality, and also because it ensures that there is good quality and uniform bonding. If any windings were not bonded correctly the coil would vibrate during use, adversely affecting inductance. Such a vibration would be available in many cases. Another advantage is that the apparatus works with a wide variety of mandrel sizes and shapes, thus allowing excellent versatility for production of a range of different pedestals. It will also be appreciated that operator time input is reduced. This feature, coupled with the excellent production quality with little waste and re-work, reduces manufacturing cost. A further advantage is that operators are not required to be in the immediate vicinity of wire as it is being drawn, thus enhancing operator safety.
The invention is not limited to the embodiments described but may be varied in construction and detail.

Claims

An apparatus (1) for producing coils of bondable wire (6) for a security pedestal, the apparatus comprising:-

a drum (2) for housing a wire reel (3), said drum comprising a lower reel-supporting base and an upper eyelet (4) for guiding wire as it is drawn from a reel (3);

a pre-tensioner (10) mounted downstream of the drum and comprising means for pre-tensioning wire as it is drawn from a reel;

a primary tensioner mounted downstream of the pre-tensioner and comprising means for applying additional tension to wire drawn through the primary tensioner;

an alignment mechanism (30) mounted downstream of the primary tensioner, the alignment mechanism being mounted on a traverse unit (42) comprising drive means for moving the alignment mechanism in a transverse direction with respect to wire travel to a desired transverse position;

a mandrel hub (55) and associated drive mounted in a protective housing (40) connected to the traverse unit, said mandrel hub comprising means for supporting a mandrel chosen from a range of different mandrel types; and

control means for causing the traverse unit to move to a selected transverse position for alignment of wire, and for causing the mandrel hub to rotate at a speed chosen according to the configuration of a mandrel (50) mounted on the hub and to draw wire from the reel at a desired speed.
An apparatus as claimed in claim 1, wherein the apparatus comprises a crimping device (32) mounted in the alignment mechanism (30).
An apparatus as claimed in claim 2, wherein the alignment mechanism (30) comprises at least two alignment wheels (31, 33), and the crimping device (32) is mounted between said alignment wheels (31, 33).
An apparatus as claimed in claims 2 or 3, wherein the crimping device (32) comprises a pair of opposed crimping jaws configured to bend the wire (6).
An apparatus as claimed in any preceding claim, wherein the control means comprises means for moving the traverse unit (42) to one transverse extremity for a first layer of windings on a mandrel, to an opposite transverse extremity for the second layer of windings, and to a central position between said extremities for subsequent layers.
An apparatus as claimed in any preceding claim, wherein the feed drum eyelet (4) comprises a lining of ceramic material.
An apparatus as claimed in claim 6, wherein the eyelet is mounted in a cross-bar extending across and above the reel-supporting base.
An apparatus as claimed in any preceding claim, wherein the primary tensioner (20) comprises a wheel (21) having a rim groove for receiving wire wound around the wheel, and means (22, 23) for adjusting wheel rotational resistance.
An apparatus as claimed in claim 8, wherein said adjustment means comprises an axial brake (23) and means (24, 25) for adjusting brake pressure.
An apparatus as claimed in claims 8 or 9, wherein said adjustment means comprises a wheel and belt assembly (22) and a bias means pressing said assembly against the rim of the wheel (21).
A method of producing a security pedestal, the method comprising the steps of:

connecting wire of the type having a bondable cement outer cladding to a mandrel, and rotating the mandrel to draw the wire from a reel in the axial direction of the reel through an eyelet, and through:

a pre-tensioner (10) at which initial tension is applied to the wire (6),

a primary tensioner (20) at which a selected primary tension is applied, and

an alignment mechanism (30),

moving the alignment mechanism in a direction transverse to the wire travel to a desired position for each layer of wire wound onto the mandrel (50),

forming a bend in the wire as it travels through the alignment mechanism,

cutting the wire when sufficient wire has been wound onto the mandrel (50),

directing electrical current through the wire to cause the cement to bond until the coil is a unitary structure, and

mounting the coil in a pedestal frame, and soldering a circuit connector to the coil at the bend in the wire.