APPARATUS FOR WRAPPING DEMAGNETIZING COILS WITH INSULATING TAPE

Abstract: Apparatus (11) for automatically forming demagnetizing coils, comprising a hank (27') of electric wire (27) and a sheath (24'') of plastic material, made from a flat tape (24) progressively curved longitudinally to form a channel by a shaping guide (35) and placed in the circumferential groove (69) of a drum (20), there being a pincer (23) which, during rotation of the drum (20), lays one (25) of the longitudinal edges of the tape (24) over the hank (27) and lays the internal surface of the second edge (26) over the external surface of the first edge (25), there being a device (140), (145), (149) placed after the pincer (23) which welds, during rotation of the drum (20), the two edges (25), (26) of the tape (24).

Description: Apparatus for wrapping demagnetizing coils with insulating tape. Ordinary demagne izing coils are composed of a continuous hank of plastic-sheathed electric wire and are made by the following methods: - the sheath, produced by extrusion through a special ma- chine . may be given an almost square cross section with the two edges laid one over the other to assist welding, . may have one longitudinal edge thickened and the other pincer-shaped to receive and enclose the first, . may have its edges bent longitudinally to allow their inside surfaces to be welded together, - sheathing may consist of a tape wound spirally round the hank, - the tape may be shaped longitudinally round the hank by a machine so that its two longitudinal edges overlie inter¬ nally creating an external rib which is then welded, - two machines may be used, one for closing the sheath and the other for welding it. There are drawbacks to all these methods. The tape extruded in some particular shape is more costly and more bulky than one of the ordinary flat tapes on the market . The sheath that is completed by fitting one edge inside the other specially made to receive it, is not only bulky but also insufficiently stable. Overalapping the edges internally forms a lon ' gitudinal rib on the outside which is both bulky and of an unpleasing ap¬ pearance . A spirally arranged tape is discon inuous, irregular and unsatisfactory for purposes of insulation. The- use of two machines, one for uniting the sheath and the other for welding it, means high equipment and running costs. This present invention avoids these drawbacks at the same time offering considerable advantages as well be explained below. Subject of the invention is an apparatus for automa ically producing demagnetizing coils comprising a hank of electric wire and a plastic sheath. The sheath is made from an ordinary flat tape made to curve channelwise gradually along its length by means of a shaping guide, and is laid in the circumferen ial groove of a rota¬ ting drum. The drum consists of two disks, one fixed to a drive shaft and the other being free to detach itself from the first, translating away by means of a me.chanism but drawn along by rotation of the shaft. In this way the demagnetizing coil can be discharged and allowed to pass between the two disks. One end of a pin is attached, but rotatable, near the edge of the disk fixed to the shaft while the other end, having passed through the translatable disk, supports a perpendicu¬ larly set arm placed in contact with a cam held to the outer side of the latter disk, by means of a spring. A spike is mounted on the pin,, at the point where there is a recess in the groove of the drum, said spike being bent in the direction opposite to that of the movement and inclined towards the inside of said groove to allow the tape to be hooked on. When the demagnetizing coil is complete the drum is opened, namely the translating disk moves away from the fixed disk and, as a consequence, the cam, cting on the arm, determines rotation of the pin and therefore inclination of the spike towards the outside of the drum, allowing the coil to be¬ come detached. At the start of the cycle a pincer gradually curves the long_ itudinal edges of the tape laying them over the hank. Each of the pincer's two jaws has at its end an articulated arm held in place by a spring and by a limit stop inside the pincer. Inside said arm a head is fixed, said head containing a groove shaped similarly to the arc of a circle open to approximately 90°. The end of said arc, innermost towards the pincer's ar¬ ticulation is substantially at 90° to the side of the arm. Therefore, when the first aw approaches the drum, contact between the end of the arm and the side of the drum causes said arm to rotate in its articulation overcoming resistance set up by the spring. The effect of this movement is to bring the groove in the head close to the hank of wire, rotating towards said hank and causing one edge of the tape to curve and overlay said hank. The second aw then moves and lays the inner surface of the other edge of the tape over the outer surface of the first one. A device, placed immediately beyond the pincer, comprising a roller to press down the edges of the tape together with a blowpipe for emission of hot air and a blowpipe for cooling air, welds the two edges of the tape by simultaneous applica¬ tion of pressure and heat. When the electric wire, fed in from a store to form the hank, has passed across a recess in one of the edges of the groove in the drum, it becomes hooked onto one. side of said drum. The tape and electric wire having been hooked to the drum and after the drum has completed about one turn, the tape is cut off at a point where it can sufficiently well over¬ lap the end hooked to the drum and the automatic cycle then begins, as follows: - the han is formed within the channel shaped tape, this being done by a previously fixed number of drum turns, - the pincer functions causing the tape's edges to curve, - the welding device welds the edges, - the number of turns are made needed to form and weld the sheath along the whole length of the demagnetizing coil, - the machine stops. This sequence is operated and checked by an electronic unit comprising a programmer, together with various devices for control and information. A number of sensors: cause the second jaw of the pincer to operate after the first jaw has completed curving of the first edge of the tape; bring the pressure roller up to the drum when the second j w has completed curving the second edge of the tape; cause the welding blowpipe to func ion after the: .pressure..- roller has completed its stroke; open the drum to discharge the demagnetizing coil when said coil is complete Characteristics and purposes of the invention will be made even clearer by the following example of its execution il¬ lustrated by drawings. Example of execution Fig.1. Dual machine unit working according to the process subject of the invention, seen from the front. Fig.2. Perspective showing functioning of a machine. Fig.3. Perspective showing detail of the drum when open. Fig.4. Perspective showing detail of the drum when closed. Fig. 5. Perspective view of the tape guide. Fig. 6. Diagram of side view of the machine when idle. Fig. 7. Diagram of side view of the machine when the tape has been hooked on. Fig. 8. Cross section detail of the drum. Fig. 9. Diagram of side view of the machine when the elec¬ tric wire has been hooked on and the tape cut off. Fig.10. Cross section detail of the drum when all turns of the coil have been completed. Fig.11. Cross section detail of the drum with the pincers open . Fig.12. Side view detail of the drum after approach of the first pincer jaw. Fig.13. Cross section detail of the drum after closure of the pincers . Fig.14. Diagram of side view of the machine after closure of the pincers . Fig.15. Diagram of side view of the machine following ap¬ proach of the welding device. Fig.16. Cross section detail of the drum. Fig.17. Diagram of side view of the machine when the demag¬ netizing coil has been completed at the moment when the electric wire is cut. Fig.18. Perspective view of a demagnetizing coil extracted from the machine. The complex ( 10) comprises the two subs antially similar ma¬ chines ( 11), ( 12), the control unit ( 13), the pneumatic unit ( 14), the electric-electronic unit ( 15) and the base ( 16). Each machine can operate independen ly of the other so that one sequence of functions can proceed while the other machine is being prepared for the next sequence. The machine (11) comprises the framework (17), the drum (20) drawn along by the shaft (30), the step-by-step el¬ ectric motor (31), the transmission (32), the reel (46)for feeding in the tape (24), the pincers (23) for shaping the sheath (24 ,τ ),(Fig.13),the. electric wire (27) container (S7 ) , the programmer (28) fixing the number of turns for each coil, the button switch (34) for starting up the machine. The reel (46) is served by the brake consisting of the rol¬ ler (40) fixed to the reel, the block (41) articulating on the pin (42) in said lever (43) pivoting at (44) and loaded by the traction spring (45). As will be more fully explained below, the tape (24), hrough the transmission wheels (48) (48') and (49), (49') and the shaping guide (35), can be hooked to the drum (20). The drum is made up of the disk (21) mounted on the shaft (30) (see also Figs. 3 and 4) and of the disk (22) caused to rotate with said shaft but free to translate pushed by the bushing (50) fixed to the sleeve (51). Said sleeve is worked by the fork (52) fixed to the lever (53) rotating on the pin (54) of support (55). At the other end of the lever the pin (56) connects it to the piston(57) of the pneumatic cylinder (58) worked by the handle (33) see (Fig.1 ) . The smaller shaft (61) is mounted on the disk (21) by screw (60), said shaft passing through disk (22) and emerging near to the cam (62) fixed in position by screws (63), (64). The perpendicular arm (65) is mounted on shaft (61) and is connected to the pin (66) •• on disk (22) by traction spring (67). Also on said shaft (61) is mounted the spike (68) between the two disks (21) and (22). When disk (22) is detached from disk ( 21 ) . (Fig.3),cam (62) by action on arm (65), has caused the shaft (61) to rotate un_ til it orientates the spike (68) to turn away from drum (20). When however disk (22) is pushed up against disk (21), said cam no longer prevents rotation of shaft (61) by action of spring (67). The spike (68) thus becomes inclined towards the drum (Fig.4) and so can hook onto the tape when the cycle starts. When the two disks (21), (22) match up together they com- plete the circumferen ial groove (69) (Fig.4) while spike (68) lies between the notches (88) and (89) cut in the edges of said disks. At its other end, shaft (30) sustained by supports (70), (71), carries the cog wheel (73) forming part of the transmission unit (32) which comprises the secondary shaft (72) carrying cog wheels (74) and (75). Cog wheel (76) is mounted on the shaft (79) carrying the step 'by-step motor (31). The cogged belts (77) and (78) respectively connect the pairs of cog wheels (73), (74) and (75), (76). Corresponding with shaft (30) is the electronic control de¬ vice (86 ), connected to the electronic unit ( 15 ) , comprising disks (80), (81) notched at (82) and (83) in order so to create pulses on the photoelectric cells (84), (85). Passing over transmission rollers (90), (91), (92), he electric wire (27) is brought near the drum (20) slowed down by pin¬ cers (93), (94). At the free end of lever (-100) pivoting at ( 101), fork( 102) articulates connected by the compression spring ( 103) to the strut( 104) articulating by pin ( 105) , on lever ( 106) pivoted on the bracket ( 107 ) . The pin (108) is mounted on lever (100) carrying the rol¬ ler ( 109) . Notch (96) is cut into the edge of disk (21) of the drum (20), said notch allowing passage of the end of the elec- trie wire (27) and hook-up to spring (97) mounted inside a hole (98) in disk (21) (see also Fig.10). At the point of drum (20), the pincers (23) are placed, with jaws (110), ( 111) articulating on pin ( 112) (see also Fig.11), comprising arms (113), (114) with rounded ends (125), (126) said arms articulating in pins (115), (116), respectively supporting head (117) with its groove (118) and head (119) with its groove ( 120). The upper ends, respectively (118') and ( 120') of said grooves are at about 90" in relation to the sides of the arms. The heads are respectivel-y pulled by the traction springs (121), (122) against the ends of the end-stroke screws (123), (124) adjusting the position of said heads. The jaws are worked respectively by the pneumatic cylin¬ ders (130), (131) suspended to rods (132), ( 133). Close to the circumference of the drum a device is placed, supplying heat and pressure, for welding the edges of the sheath, and including blowpipe ( 140) emitting hot air from the body (141) containing electric resistances, supported by shaft ( 142) to which is fixed the arm (143) connected to the pneumatic cylinder (144). The pressure roller (145) is placed immediately beyond the blowpipe, said roller being supported by the angular lever (146) p-ivoting at (147) and operated by the pneumatic cy¬ linder (148). Near to the roller is the nozzle (149) blowing out cooling air . The shaping guide (35), (Fig.5) comprises an initial flat part (35') with the edges (36), (37) bent back so as to create a rectangular fissure and a final part (35") ap¬ proximately V-shaped. The edges (36'), (37') inside said "V", remain practically parallel to the outer faces of the guide. There is a hook (38) on the back side of the guide whose purpose is to fit onto the pin (39) placed on the machine near the drum (20), (Figs. 2 and 7). In Fig. l the machine ( 12) shows the main features corres¬ ponding to those of machine( l l) such as the frame ( 150), the drum ( 151), the shaft ( 152), the step-by-step electric motor ( 153), the transmission ( 154), the handle (155), the reel ( 156) supplying tape ( 157), the pincers ( 158), the feeder ( 159) of electric wire ( 160), the numberer ( 161), and the starting button switch ( 162). Operation The flat end of the tape (24), (Figs. 5,6,2) is placed in mouth (35') of the shaping guide (35) from which it emerges at (24') in the form of a "V". The drum (20), (Figs. 3, 4) is closed by acting on lever (33), (Fig.1. ) . In this way the end of the tape (24') can be hooked onto the spike (68) (Figs. 7,8) while the hook (38) at the back of the guide (35) is applied to the horizontal pin (39), Figs. 2, 7). The electric wire (27) is hooked to spring (97) on disk(21) making said wire pass through the transmission roller ( 109) and the notch (96) in said disk (Figs. 2, 9, 10). Drum (20) is rotated until a length of tape (24' ) is com¬ pletely wound on it and slighly overlies the end already hooked to the spike (68) and an initial turn of electric wire is completed round the tape. Said tape (24 ') is then cut by hand close to the drum and the guide (35) is overturned to allow the tape (24) to re- main over the transmission roller (49') (Fig.9). At this point a start is made with forming the coil (27') by de¬ pressing push button (34) (Fig.1) having previously set the number of turns to be made on the counter (28). When said number is nearly completed, control device (86) sends a signal to the electronic unit ( 15) which gradually slows down and stops the motor (31) at an exact point with automatic closure of the pincer jaws (23) (Figs .11 , 12, 13 ) . When the jaws (110), ( 111) approach each other, the lower rounded ends (125), (126) of the arms (113), (114) make con- tact with disks (21), (22) of drum (20) determining, at the same time , (Figs .11 , 12, 13)j gradual matching of the internal sides (113'), (114') with the sides of said disks and final matching of the lower parts of heads (117), ( 119) with the edges (21'), (22') of said disks. Jaw (110) is the first to approach the edge (25) of the tape (24). Complete contact between side (113') of the arm with side (21) of the drum causes rotation of said arm and therefore of the head (117) until the upper part (118')of the arched groove ( 118) passes from the inclined position held by it in Fig.12 to that in Fig.13 practically perpendicular to the side of the drum. Said combined movement of the groove (118), of approach to the hank (27') of wire and rotation towards said hank, fa- cilitates movement and curvature of edge (25) of the tape (24')and its superimposition on said hank (27') until the position is reached as seen in Fig.13. An electronic sensor, no shown for simplicity in the figure, sets off the second jaw ( 111) which, with the same mechanisms as before, by means of groove ( 120) in head ( 119), causes the edge (26) of tape (24') to curve round the hank (27) and "on top" of the edge (25). When the pincer is fully closed (Fig.10), another sensor signals for lowering of the welding unit (Fig.15)and for ro¬ tation of about one turn of the drum to allow the edges (25) and (26) of the tape to be welded along the whole circumfer¬ ence of the coil creating a circular and continuous sheath (24") (Figs. 16, 18) around the hank (27')of electric wire. The welding device and pincers then automatically move away from the drum and the machine stops. Hand scissors (59) are used to cut the electric wire (27) (Fig.17), the drum is opened by lever (33) (Fig.1) and the coil (29) complete with sheath (Fig.18) can be extracted by making it pass between disks (20), (21). The machine (Fig.18) has by then returned to its position in Fig.6, ready to begin a fresh cycle. Advantages Considerably lower sheath cost as an ordinary flat tape is used and not one specially extruded. Maximum adherence between the sheath and the hank of electric wire without any bumps, ribbing or roughness. Minimum overall bulk of the coil. An appreciably better appearance. Maximum functionality.

Claims: CLAIMS " 1. Apparatus for automatically forming demagnetizing coils comprising a hank of electric wire and a plastic sheath, cha¬ racterized in that the sheath (24") is made from a flat tape (24) gradually curved like a channel (24') along its length by a shaping guide (35) and placed in the circumferential groove(69)of a rotating drum (20), a pincer (23) with two jaws ( 110) , ( 111 ) , the hank (27')having been formed in said channel (24 '), gradually curving the longitudinal edges (25), (26) of channel (24') laying edge (25) over the hank (27') and over¬ laying the- inside surface of the second edge (26) on the oute surface of the first edge (25), a welding device (140), ( 145) (149), placed after the pincer (23), then welding said edges (25), (26) of the tape (24_')during rotation of the drum (20). 2. Apparatus for automatically forming demagnetizing coils as in claim 1, character zed in that the two jaws (l ' 10),( l l l operate independently, the first jaw (110) laying one edge (25) of channel (24') over the hank (27') of electric wire (27) and the second jaw ( 111) immediately after laying the edge (26) of channel (24') over the edge (25). 3. Apparatus for automatically forming demagnetizing coils as in claim 1, characterized in that an arm (113), (114) is articulated at the end of each of the two jaws ( 110) , ( 111 )of pincer 023), said arm held in place . by a spring ( 121), (122) and by an end-stop (123), (124) inside the pincer (23), there be¬ ing fixed inside said arm (113), (114) a head ( 117), (119) in which is a groove ( 118), (120) shaped similarly to an arc of a circle open to about 90°, said arc's extremity ( 118 ' ) ,( 120' nearer the inside of the pincer (23)>. being " substantially at an angle of 90° to the side ( 113 ' ) , ( 114 ' ) of arm (113), (114) the other extremity being turned in the direction of the jaw ( 110), ( 111), substantially parallel to said side ( 113'), ( 114'), so that as one jaw approaches the drum (20), due to contact of said jaw's end with the side of the drum its arm ( 113), ( 114) is obliged to rotate overcoming the resistance opposed by the spring ( 121), ( 122), while the groove ( 118), ( 120) of the head ( 117), ( 119) rotatingly ap¬ proaches the hank ( 27 '), curving the edge (25), (26) of the tape (24') and drawing it towards said hank. 4. Apparatus for automatically forming demagne izing coils as in claim 1, characterized in that welding is done by simultaneous application of pressure and heat, comprising in the welding device, placed immediately after the pincer (23), a roller ( 145) for pressing down the edges (25), (26) of the tape (24') overlying the hank (27'), a blowpipe ( 140) for emission of hot air and a blowpipe ( 149) for blowing on cooling air . 5. Apparatus for automatically forming demagne izing coils as in claim 1, characterized in that the shaping guide (35) comprises a rectangular entry mouth (35') practically the same size as the flat tape (24) and an exit mouth (35") shaped substantially like a "V" with an arched base substan¬ tially corresponding to the circumferential groove (69) in the drum (20). 6. Apparatus for automatically forming demagnetizing coils as in claim 1 characterized in that the drum (20) is com¬ posed of two disks (21), (22), one of them (21) being " fixed to the drive shaft (30) and the other (22) free to detach itself from the first (21) translating by means of a spe- cial mechanism but drawn in rotation by the shaft (30), said detachment allowing the demagnetizing coil (29) to be dis¬ charged, one end of a pin being rotatably attached near the edge of disk (21) fixed to shaft (30) while the other end having passed through the translatable disk (22) sup- ports a perpendicular arm (65), placed in contact with a cam (62) fixed to said latter disk (22), .by means of a spring (67), a spike (68) being placed on the pin (61) at a point Where there is a recess (88), (89) in the groove (69) of the drum (20), said spike facing in the opposite direction to drum movement and inclined towards the inside of the groove (69) so as to facilitate hook-up with the tape (24), rotation of pin (61) being caused, when the drum (20)is opened namely when the translating disk (22) becomes detached from ' the fixed disk (21) by the effect of the cam (62) on the arm (65), and therefore inclination of the spike (68) towards the outside of the drum (20) thus facilitating discharge of the completed coil (29). 7. Apparatus for automatically forming demagnetizing coils as in claim 1, characterized in that the tape (24') and the electric wire (27) having been hooked to the drum (20),when said drum has completed about one turn and when said tape (24') has been cut at- a point that will allow it to .overlie sufficiently the one end hooked to the drum (20), a start is made with the automatic cycle comprising: formation of the hank (27') in the groove (69) of the tape (24'), action by the pincer (23) to curve the edges (25), (26) of the tape (24') around the hank (27'), action by the welding device with its pressure roller " (145) and blowpipe ("140), comple¬ tion of the turn needed to form and weld the- sheath (24") to enclose the demagnetizing coil (29) and stoppage of the machine (11), said cycle being operated and controlled by an electronic unit ( 15) comprising a programmer and var ¬ ious devices (80, 81, 82, 83, 84, 85, 86) for control and information. 8. Apparatus for automatically forming demagne izing coils as in claim 7, characterized in that a number of sensors, connected to the electronic unit ( 15): bring into action the the second jaw ( 111) of the pincer (23) when the first jaw ( 110) has finished curving the first edge (25) of the tape (24'), cause the pressure roller ( 145) to approach the drum (20) when the second jaw ( 111) has curved the second edge (26) of the tape (24'), bring into action the welding blow¬ pipe ( 140) when the roller ( 145) applying pressure has com- • pleted its stroke, open the drum (20) to discharge the de¬ magnetizing coil (29) when said coil has been completed.

Inventors: COVINO AUSTERO, COVINO, AUSTERO
Applicants: COVINO AUSTERO, COVINO, AUSTERO
Application year: 1987
Main classification: H01F41
IPC codes: H01F41