Abstract:
A pressure sensitive valve is mounted on the barrel of a magnet wire spool to be closed by wire wrapped on the barrel. Superatmospheric pressure is maintained internally of the barrel which is released upon opening of the valve by removal of the wire from the spool. A pressure-sensing device activates in response to such pressure release to provide a warning signal or suitable control function.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention is in the field of wire carrying spools, and more particularly to a signaling or control device which is activated upon removal of the base layer of wire being payed from the spool. 
     2. Description of the Prior Art 
     Magnet wire from which magnetic coils are fabricated is conventionally stored on spools having a barrel provided with end flanges. A filled spool is conventionally fitted to apparatus for winding coils, the wire being payed off the spool being through the intermediary of a de-reeling device in some instances and in others directly from the spool mounted for rotation on an arbor. The condition of all of the wire is payed off or unwound from the spool, may go undetected unless the operator is observing the operation closely. If this condition is not observed, the coil-winding apparatus, which is usually electrically operated, continues to run until it is manually shut down. It frequently occurs that one person is in charge of operating a number of coil-winding machines such that the emptying of a particular spool often goes undetected. 
     SUMMARY OF THE INVENTION 
     A spool apparatus is provided with a hollow, air tight barrel and conventional end flanges. An opening in the barrel wall is fitted with a valve which seals the opening when a base layer of wire is normally coiled onto the barrel but breaks the seal when this layer or a portion thereof is removed. The valve is so arranged that superatmospheric pressure internally of the barrel unseats the valve to cause a drop in pressure, indicating exhaustion of the wire supply. 
     A pneumatic system is coupled to the barrel interior and comprises a source of low pressure air, a conduit leading from the source to the barrel interior, a second conduit leading from the barrel interior to a pressure operated sensing device such as an electrical switch, and a signaling or control device connected to the sensing device capable of producing a signal or control function in response to of the activation of the sensing device. During the unwinding of a loaded spool, as in the case of operation of coil-winding apparatus to which wire is being fed, the valve is closed by the wire on the barrel and air under pressure from said source fills the interior and is applied to the sensing device maintaining the latter deactivated. When the base layer of wire is reached and a predetermined number of coils are unwound, the valve is released permitting the escape of air from and reduction of pressure within the barrel. This pressure drop is communicated to the sensing device thereby activating it. A signaling or control device coupled to the sensing device is then energized thereby providing an indication or control function indicative that the spool is empty or nearly empty. 
     In one embodiment, the valve is in the form of a normally open poppet valve that is held closed by the contiguous wrapping of wire on the barrel. Various designs of barrel spools may be used such as round, tapered or polygonal. 
     An object of this invention is to provide a device method and an apparatus for generating a signal to warn or to provide a control signal indicative of an empty spool condition. 
     A still further object of this invention is to provide in the apparatus of the previous object means to automatically stop the unwinding of wire from a spool mechanism upon nearing an empty spool condition. 
    
    
     The above-mentioned and other features and objects of this invention and the manner of attaining them will become more apparent and the invention itself will be best understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view, partly diagrammatic, of an embodiment of this invention relating to an empty spool signaling device; 
     FIG. 1A is a diagrammatic view of a warning circuit which may be incorporated in the embodiment of FIG. 1; 
     FIG. 2 is an enlarged sectional view of one valve structure taken substantially at section line 2--2 of FIG. 1; 
     FIG. 3 is a partial view of the valve structure of FIG. 2 taken substantially at section line 3--3 of FIG. 2; 
     FIG. 4 is an enlarged partial section of the valve structure of FIG. 2 shown in an open, empty spool condition; 
     FIG. 5 is an enlarged view of a second embodiment of a valve for use with round spool bodies; 
     FIG. 6 is a fragmentary section taken substantially at section line 6--6 of the valve embodiment of FIG. 5 as applied to a round body and held in a closed valve position by wire windings; and 
     FIG. 7 is an enlarged partial section similar to FIG. 6 showing the valve structure of FIG. 6 in open position as in a spool empty condition. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The empty spool indicating or control apparatus of this invention may be used with various conventional barrel configurations such as round, tapered, polygonal and the like. For convenience in describing the apparatus, a spool having a polygonal barrel is first described. 
     Referring more particularly to FIGS. 1 through 4, a spool 70 has a polygonal barrel (actually octagonal) 74 having flat sides 72. Flanges 76 and 78 are hermetically attached to the opposite ends of the barrel 74 as shown. The barrel 74 has a hollow interior with the wall thereof being impermeable to the passage of air, and in operation of the apparatus is charged to a predetermined superatmospheric air pressure. The flange 76 secured to the upper end thereof is provided with a central opening 86. Superposed on the flange 76, which for convenience is provided with a flat upper surface, is weighted sealing plate or relief valve 80 having a gasket or O-ring 82 between it and the upper surface of the flange 76. A handle 84 is secured to the plate 80 for convenience in placing the plate 80 in position on and removing it from the flange 76. While in the illustrated embodiment the seal 82 is shown as being in the form of an O-ring coaxially positioned with respect to the opening 86, it is to be understood that any suitable sealing or gasket device may be used without departing from the spirit and scope of this invention. The purpose of the weighted sealing plate 80, 82 is to prevent the escape of air from the interior of the barrel 74 via the opening 86 and also to serve as a relief valve should pressure within barrel 74 exceed a predetermined level. 
     The plate 80 is selected to be of an appropriate weight to provide the necessary seal that will prevent the escape of a predetermined superatmospheric pressure within barrel 74 via the opening 86 as later explained. While the opening 86 is disclosed as being sealed by means of the valve plate 80 and gasket 82, still other valve means may be employed such as a rubber stopper (not shown) inserted into opening 86 which will eject upon exceeding the predetermined pressure in barrel 74 or a conventional air pressure relief valve (not shown) connected to opening 86 which will open under the same excessive pressure condition. 
     The spool 70 is rested on a flat element or bench top 79 with an O-ring seal 81 disposed between the upper surface of the top 79 and the flange 78. Again, this seal 81 may be in the form of an O-ring seal or suitable gasket thereby to provide an air tight chamber 97 between that portion of the flange 78 inside the seal 81 and the upper surface of the bench top 79. An opening 90 is provided centrally of the flange 78 for communication with the interior of the barrel 74. So mounted and with the valve plate 80 in position, the interior of the barrel 74 is in the form of a hermetically sealed air chamber. 
     A source 92 of low pressure air is connected by means of a conduit 94 to an opening 96 in the bench top 79 which communicates with the sealed chamber 97 between the flange 78 and the bench top 79. A like conduit 100 connects to another opening 98 in the bench top 79 which is also in communication with the chamber 97 and to a conventional low pressure, pneumatically operated electrical switch assembly 102. This switch assembly 102 contains either a diaphram or piston exposed to the pressure in the conduit 100 which carries the movable contact of a single pole single throw switch. In one embodiment it is preferred that under normal operating pressures in the conduit 100, the contacts of the electrical switch 104 of assembly 102 will be held closed, but upon reduction of this pressure to a predetermined level, the contacts will be opened. This switch 104 is connected in series with a suitable source 108 of electrical power and a coil-winding machine which receives wire payed off the spool 70 by means of conventional overhead de-reeling apparatus indicated diagrammatically by the line 116. When the switch 104 is closed, the power source 108 energizes the coil-winding mechanism 114 which functions in a conventional manner to produce wire wound products such as electric motor stators, magnets and solenoids. 
     Instead of controlling the operation of the coil-winding mechanism 114, the switch 104 may be connected in circuit with a sound-producing device 118 (FIG. 1A), such as a buzzer, and a warning lamp 120. A battery (not shown) may be connected in series with these elements 118 and 120 such that upon closure of the switch 104, both the buzzer 118 and the lamp 120 will be energized. 
     Mid-way between the ends of the spool 74 and centrally of one of the flats 72 is a chamfered circular opening 124, better shown in FIGS. 2 and 4. A flexible, relatively flat, rubber valve 126 is operatively mounted in this opening 124 and serves to close and seal the same when positioned as shown in FIG. 2 and to open the same as shown in FIG. 4. This valve 126 is provided with four divergent legs 130 arranged in quadrature terminating in upturned retaining tips 132, for operatively retaining the valve 126 assembled in the opening 124. As shown in FIG. 4, when the valve 126 is opened, the tips 132 engage the underside of the marginal portions of the opening 124 to thereby prevent withdrawal of the valve 126 from the opening 124. 
     In explaining the operation of the invention thus far described, it will be assumed that wire has been conventionally wound in multiple layers on the barrel 74 between the flanges 76 and 78, each layer consisting of a multiplicity of contiguous turns. Also it will be assumed that in operating the coil-winding mechanism 114 and de-reeling device 116, the de-reeling device is of the conventional, overhead type which directs the wire vertically off the spool 70 about flange 76 in feeding it to the mechanism 114. With the wire so wound on the barrel 74, coils 136 (FIG. 2) will hold the valve 126 in sealed position in the opening 124. As wire is payed off the spool 70, it will eventually reach the final layer contiguous with the barrel 74. As this final layer is payed off, it will eventually uncover the valve 126 permitting it to unseat in response to superatmospheric air pressure maintained in the barrel interior. The reduction in pressure in the barrel 74 is communicated to the pneumatic-sensing device 102 via the conduit 100. This results in opening the switch 104 (in this instance being maintained closed by the superatmospheric pressure) and severing the power to the coil-winding mechanism 114 causing it to shut down automatically. 
     In obtaining this operation, the interior of the barrel 74 is maintained at a predetermined pressure by means of the pressure source 92 and conduit 94. A suitable pressure is about ten pounds per square inch gauge. Air under pressure from source 92 is communicated to the chamber 97 via the line 96. The same pressure prevails inside barrel 74 by reason of the small flange aperture 90. Correspondingly, the same pressure prevails in conduit 100 maintaining pneumatic-sensing device 102 deactivated. Again, when the wire uncovers the valve 126 as previously explained, this internal barrel pressure will unseat the valve 126 permitting a reduction in the pressure internally of the barrel 74. This reduction in pressure communicated to chamber 97 is sensed as previously explained to sever the operating power for the mechanism 114. 
     Instead of using the sensing device 102 for the purpose of shutting down the mechanism 114, an audio-visual warning device in the form shown in FIG. 1A may be used. In this instance, the switch contacts are held open by the superatmospheric pressure. Upon a predetermined drop of pressure in line 100, both the devices 118 and 120 will be energized upon closure of the switch to warn the machine operator that the spool 70 is approaching empty condition. 
     A slightly different valve device is shown in FIGS. 5 through 7 for use in conjunction with a cylindrical barrel of uniform diameter or tapered. This barrel is shown in fragmentary form and indicated by the numeral 140. In the barrel wall, again mid-way between the barrel ends, a series of apertures 142, a total of nine as shown in the drawings, are arranged in columnar form. This valve 146 is relatively flat and flexible and of sufficient size to cover over and seal all nine of the openings 142. At the corners of this valve 146, which is shown shaped as a square, are four retaining stubs 150 which are received with clearance by four of the openings 142. Integrally formed on the ends of the stubs 150 are enlarged retaining heads 152 of a transverse dimension larger than the respective openings 142. As shown in FIG. 5, these heads 152 are flat, but may be conically shaped instead. The valve 146, stubs 150 and heads 152 are integrally molded preferably of some soft rubber-like material so that the heads 152 may be deformed in assembling stubs 150 through the respective holes 142. In closed condition, the valve 146 overlies and seals all of the openings 142. When opened, the valve 146 is spaced beyond the outer surface of the barrel 140 thereby providing an escape path for the air under pressure within the barrel to escape through the openings 142. 
     This embodiment of FIGS. 5 through 7 operates essentially identically to that of the previous figures, wire wrapped on the spool 140 as indicated by the numeral 160 in FIG. 6 holding the valve 146 closed. When this wire is payed off, the air under pressure inside the barrel forces the valve 146 open thereby providing the reduction in pressure sensed by the device 102. 
     The pressure relief valve 126 or 146 may be located at any desired point on the barrel between the ends thereof so as to obtain the desired sensing operation. This will depend upon the type of operation desired by an operator. This invention is particularly useful in preventing the expiration of wire off the spool 70, which usually is being drawn at high velocity, before parts being produced by the mechanism 114 have been completed, for preventing the freed wire end drawn off an empty spool from whipping violently through space before it is drawn into the mechanism 114 and thirdly to prevent damage to equipment in the event the end of the wire is tied to some portion of the spool such as the flange. In the latter instance, when the spool is totally empty, the spool can be forcefully carried against the de-reeling or coil-winding mechanism causing damage thereto. 
     In the use of this invention, and by locating the valve 126, 146 mid-way between the barrel ends, a warning is sounded or the winding machinery is shut down before all of the wire is payed off the spool. This permits manual operation of the coil-winding machinery for completing any products in the process of being wound before all of the wire is payed off the spool. This results in an economy with respect to maximizing the use of the wire on the spool to make completed parts with a minimum of waste, constitutes an item in safety in preventing a free end of wire off the spool from whipping violently and possibly injuring an operator, and further prevents the spool from being drawn against associated machinery should the free end be tied to some part of the spool. 
     The air pressure system of this invention operates at a constant, relatively low pressure, ten inches water column being typical. The relief valve 80 is so designed to tilt slightly to open should the pressure inside barrel 74 exceed ten inches water column, thereby maintaining the pressure relatively constant as the valve 80 will gravitationally close, when opened, as the pressure drops below ten inches. The pressure-sensitive device 102 is selected to be activated when the pressure in the barrel 74 drops a predetermined amount of, for example, five inches or to atmospheric. These parameters may, of course, be altered without departing from the spirit and scope of the invention. 
     While there have been described above the principles of this invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of the invention.