US2656127A - Apparatus for locking cop tubes on cop winding machines - Google Patents

Description

Oct. 20, 1953 BUNCH 2,656,127

. APPARATUS FOR LOCKING COP 'SI'UBES 0N COP WINDING MACHINE Filed June 8, 1949 2 Sheets-Shget l 24 -4 22 FIG. 2

IN 5 N TOP r- 7. BU/ VCH A T TORNE V Oct. 20,1953 'r. T. BUNCH 2,656,127

- APPARATUS FOR LOCKING COP TUBES 0N COP WINDING MACHINES Filed June 8, 1949 2 Sheets-Sheet 2 INVENTO R 7: 7. BUNCH BY FIG 6, ATTORNEY Patented Oct. 20, 1953 UNITED STATES PATENT OFFICE APPARATUS FOR LOOKING COP TUBES ON COP WINDING jMACHINES Tillman "r. Bunch, As'hland, Md., assignor. to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application June 8, 1949', Serial No. 97,832

9 Claims.

such as are employed in th manufacture of insulated electrical conductors or the like. The winding spindles of cop winding machines are provided with variousmeans for holding the cop tube on the spindle during the cop winding operation. It is desirable that the cop tube holding means he a type which engages and disengages the cop tube with a minimum amount of effort and time in order to obtain a maximum production of cops from any given winding machine.

An object of the invention is to provide new and improved apparatus for locking cop tubes on the winding spindles of cop winding machines.

Another object of the invention is to provide new and improved apparatus for magnetically lockinga cop tube on the winding spindle of a cop winding machine.

,An apparatus embodying certain features of the invention comprises a tubular spindle on which a tubular cop tube may be slidably positioned for rotation with the spindle, and a magnetically-actuated means for holding the cop tube on the spindle while a cop is wound thereon.

A clear understanding of the inventio will be had from the following detailed description of a specific embodiment thereof, when read in conjunction with the appended drawings, in which:

Fig. 1 is a side elevation of a winding spindle embodying certain features of the invention;

Fig. 2 is a section taken along lin 2-2 of Fig. 1;

Fig. 3 is a section taken along line 3-3 of Fig. 1;

Fig. 4 is a section taken along line 4-4 of Fig. 2, and showing the magnetic-locking means of the winding spindle in its cop winding position;

Fig. 5 is a sectional view of the spindle similar to that shown in Fig. 3 in which the magnet is shown in its actuated position and the cop and cop tube are shown in a partially released positoin with respect to the spindle, and

Fig. 6 is an enlarged fragmentary, sectional 2 view showing the right-hand end of the spindle shown in Fig. 3, and showing the keeping circuit of the magnet positioned in the spindle.

Cop winding machines, in general, containone or more winding spindles arranged to be driven a suitable manner and designed to receive a cop tube on which a textile cop, or the like, is

wound to form a convenient supply package or cop to be used with serving and braiding machines. Since the general construction and operationof cop winding machines is known, only the construction andoperation of a winding feature embodying certain features of the present invention will be described in detail.

Referring to Figs. 1 and 4 of the drawings, there "is shown a winding spindle comprising a shaft 10 suitably journalled in the frame of a winding machine, a portion of which is indicated by the numeral l I, and arranged to be driven by suitable means (not shown). A hub I5 is secured on the end of the shaft 10 extending beyond the frame I l, and hasone end of an elongated tubular member 16, which is made of a magnetic material, rigidly secured on a right hand body portion 18 of the hub. The tubular member I6 is provided with four longitudinal grooves ll-Il (Figs. 2 and 6) spaced equally about the periphery of the tubular member, that is, the grooves are positioned apart.

A ring 20 (Fig. 4) is secured to the periphery of an annular flange 2| provided on the hub l5 by :means of a plurality of set screws 22-22, the inner ends of which engage a conical groove 25 provided in the periphery of the flange 2|. The ring 20 is countered-bored so as to form an annular shoulder 23 adjacent to the right end thereof, which shoulder is adapted to engage the upper edge of ribs 24-24 positioned between the bottom of the grooves ll-ll and the inner bore of the ring 20. japart about the periphery of the ring 20 so as to be aligned radially with the grooves 11-" and the ribs 24-24. The center of the conical groove 25 provided in the periphery of the flange 2! of the hub 15 and the center of th set screws 22-22 are misaligned so that when the set screws are threaded into the ring, the conical end of the screws enters the groove and draws the ring 20 to the left thereby causing the shoulder 23 to clamp the ribs tightly against the flange 2| of the hub 15.

A segment 26 (Figs. 2 and 4) is positioned between each pair of ribs 24-24 (Fig. 2), and is arranged to slidably engage the periphery of the The set screws 22-22 are spaced 90 tubular member IS and the internal bore of the ring 20. Each of the segments 26-26 is provided with a shoulder 21 adjacent to the right end thereof, which normally engages the shoulder 23 provided in the ring 20, whereby each segment 26 is retained within the ring Where it is subject to the action of a spring 28 positioned in a bore 29 provided in the segment and a bore 30 provided in the flange 2 I of the hub l5.

The free end of the tubular member it (Fig. 4) is designed to slidably receive an elongated cop tube indicated generally at 3| which is composed of two identical sections 32-32 (Fig. 6) of semicircular cross-section. Each section 32 is provided with an inwardly projecting rib 33 positioned centrally therein, and with inwardly projecting ribs t l-tt provided at the extremities thereof. When the two sections .3 2 -732 are butted together and slid longitudinally onthe free end of the tubular member Hi, the inwardly projecting ribs 33-33 and 3i34 slidably engage the grooves i'iil' provided in the tubular member and lock the cop tube thereon for rotation therewith. The internal bore of the cop tube 3! is larger than the diameter of the tubular member it, and the inwardly projecting ribs 3333 and 3d3 l coact with the grooves ii-H to align the cop tube concentrically on the tubular member so as to leave an annular clearance between the inner surface of the cop tube and the periphery of the tubular member and between each rib 34% and the bottom of its adjacent groove. The purpose of maintaining an annular clearance between the internal bore of the cop tube and the periphery of the winding spindle is to prevent the pressure imposed on the tube when a cop, indicated generally by the numeral 35, is wound on the cop tube from causing the cop tube to bind on the tubular member !6.

There is provided within the tubular member 56 (Fig. 4) means for magnetically locking the cop tube ill on the spindle against a longitudinal movement while the cop 35 is wound thereon. The magnetic locking means comprises a sleeve 36 made of bronze or other suitable non-magnetic material secured in the internal bore of the tubular member it and a sleeve 37 made of bronze or other suitable non-magnetic material secured in the internal bore of the sleeve 56 ad jacent to the end of the hub 55. netic sleeves 35 and 3? have the same internal diameters and are designed to slidably receive a cylindrical permanent magnet dii having a cupshaped pole-piece 'secured on the right end thereof and a cup-shaped polepiece 42 secured on the left end thereof by means of a bolt d3 passing through a central bore 44 provided in the magnet ii] and threadedly engaged by a nut 56. A spring il positioned within the tubular mem-- ber it between the pole-piece 42 and the end of the hub i5 normally urges the permanent magnet 46 to the right so that the annular edge of the pole-piece d2 engages the end of the mom magnetic sleeve 3?, as shown in Fig. 4.

The permanent magnet Mi (Fig. i) is so ma netized that the magnetic lines of force pass through it in a longitudinal direction as shown by the dotted lines indicated by the numeral 50 (Fig. 3). The pole-piece 42 is designed to slidably engage the internal surface of the tubular member it, whereas the pole-piece GI is of such diameter that an annular air gap exists between the periphery thereof and the internal surface of the tubular member 16. The magnetic flux indicated by the dotted line 53-40 The non-maginternal bore of the tubular serves to attract a ring 52 made or" a para-magnetic material, and holds it tightly against the end of the tubular member it because the ring 52 is provided with an internal bore 53, which slidably engages the pole piece 3!. The tubular member i5 and the ring 52 are made of ferromagnetic material and together they form a closed ferromagnetic circuit for the magnetic flux Fit-5E! as shown in Fig. 4. The magnet 4%) produces a permanent magnetic field across the annular air gap 5|.

This arrangement provides a path for the magnetic flux of the magnet at from the pole-piece 4| through the ring 52 and the tubular member [6 to the pole-piece :52, which has a reluctance substantially less than the reluctance of the annular air gap 5! between the pole-piece M and the tubular member E6. The member :5 is bevelled at 54 so as to reduce the annular contact area between the end of the tubular member l6 and the face of the ring 52 and thereby concentrate the lines of force of the magnetic circuit at the point of contact between the ring 52 and the end of the tubular member 53. The bevel 54 is designed to provide a concentration of the flux at the point of contact which will cause the magnet to attract the ring with a predetermined force.

When the ring 52 is held against the end of the tubular member [6 by the magnet 49, as shown in Fig. l, the ring serves to hold the end of the cop tube 3i flush with the end of the tubular member Hi. The cop tube 3! is of such length that when the ring 52 holds it in such position, it moves the segments 2626 to the left against the actions of their respective springs ZS-23, in which case, the spring-loaded segments serve to keep the cop tube pressed against the face of the ring and to prevent lateral movement of the cop tube on the spindle while the cop 35 is wound thereon. This arrangement of the cop tube on the spindle makes certain that the cop 35 is wound centrally on the cop tube 3!. The provision of four grooves l'il'l on the tubular member. it permits the cop tube 3! to be positioned thereon in two positions, that is, the dividing line of the two sections of the tube may coincide with the line A-A (Fig. 6) or with the line BB. The four segments was positioned in the hub I5 are arranged so that two segments engage each half section of the tube 3i for either position of the tube on the tubular member 25. While the half -sections 32-32 may vary in length with respect to each other, this arrangement of the segments 26-25 serves to maintain the right-hand end of each section against the ring 52.

The magnet 40 attracts the ring 52 to the end of the metallic tubular member It so powerfully that it may not be removed readily from the tubular member with the magnet in a position shown in Fig. 1. To release the ring from the tubular member, it is necessary to push the nut 46 to the left (Fig. 1) so as to move the permanent magnet 40 to the left until the annular edge of the pole-piece 4i engages the ends of the sleeve 36, as shown in Fig. 5. When the permanent magnet has been actuated in this manner, the pole-piece 4| is withdrawn from the centerbore of the ring 52 so that the magnetic flux between the pole-pieces 4| and 42 does not pass through the ring 52, but passes only across the air gap between the pole piece 4! and the member I6 and through the tubular member 16 as :indlc'ated by the dotted line 55. By virtue of the *air gap the external magnetic flux path 55 of the magnet 4|] is discontinuous or open-circuited. When the pole-piece 4| has been actuated to the position shown in Fig. 5, the ring is disengaged from the end of the tubular member I6 by theaction of the springs 28-28, which After the magnet 40 has been actuated in this manner to disengage the ring from the "end of the tubular member It, the magnet is released and allowed to return to its position shown in Fig. 6, in which position the magnetic lines of force between the pole pieces 4| and 42 travel across the annular air gap 5| and through the tubular member I6, as shown by the dotted line 56. The air gap 5| has sufficient reluctance to cause the magnetic flux of the magnet to pass through the ring 52 when the parts are positioned as shown in Fig. 3, but at the same time permits the flux of the magnet to travel thereacross and complete the magnetic circuit and thereby retain the magnetism in the permanent magnet when the ring 52 is not positioned against the end of the tubular member l6.

Operation The above-described winding spindle operates in the following manner:

Let it be assumed that all the elements of the spindle are positioned as shown in Fig. 4., with the exception of the fact that the ring 52 is not in position, in which case, the path of the magnetic circuit between the pole pieces 4! and 42 is shown by the dotted line indicated by the numeral 56. A cop tube of the type indicated by the numeral 3| is slid on the tubular member I 6 until it engages the spring-pressed segments 26-26 and moves them to the left against the action of their respective springs 28-28. The right end of the cop tube 3| is positioned slightly to the left of the right-hand end of the tubular member l6 and held in this position until the ring 52 is positioned over the pole-piece 4| and magnetically attracted to the end of the tubular -member l6 by the magnet 40 and the magnetic flux 50-50 (Fig. 3). When the ring is so positioned, the cop tube may be released, in which case, the springs 28-28 will move the segments to the right which segments in turn push the sections 32-32 of the cop tube to the right until the end thereof engages the face of the ring 52. Since two segments engage each half-section 32 of the tube 3 the left end of each section is held against the ring '52.

The spindle It then is rotated to wind a cop 35 on the cop tube 3|. When the cop 35 is completed, the nut 46 is pressed so as to move the permanent magnet 40 to the left against the action of the spring 41 until the pole-piece 4| engages the adjacent end of the sleeve 36 as shown in Fig. 4. With the magnet 40 in this position, the external path of the magnetic flux between the pole-pieces 4| and 42 is solely within the tubular member |5, as shown by the dotted lines 55-55 (Fig. 5). When the pole piece 4| is withdrawn completely from the internal bore of the ring 52 as described, the springs 28-23 push the segments to the right until, they engage the shoulder 23 provided in thering 20 and impart a similar longitudinal movement to the cop tube which disengages the ring 52 from the end of the tubular member It as shown in Fig. 4. When the permanent magnet 40 is released, the spring 41 urges it to the right until the pole-piece 42 again engages the end of the sleeve 31, in which case, the magnetic circuit between the pole pieces lies solely within the tubular member It, as shown by the dotted lines 56-56 (Fig. 4) When the ring 52 has been so removed from the end of the tubular member, the cop 35, including the cop tube 3|, may be removed readily from the winding spindle.

The magnetically held ring 52 provides' a quick acting locking means having a single part to be handled in locking a cop tube on a winding spindle of a winding machine and one which is designed to release the ring quickly. These features of the magnetic lock facilitate easy insertion of the cop tube on the winding spindle and quick release of the ring locking the cop on the spindle.

The permanent magnet 40 is made of a hard ,magnetizable material, which has the inherent property of retaining approximately a full con "centration of magnetic flux for a long period of time or even permanently. It also must possess the property of being capable of a very high induction of magnetic flux per unit area. of a given .size magnet. A material possessing these qualities is an alloy consisting of about 8% aluminum,

18% nickel, cobalt, 3% copper and the balance iron which is referred to generally in the art as Alnico No. 5." When a cylindrical piece of this alloy is 1 in diameter and five :inches long and having ferromagnetic pole- .pieces Al and 42 secured on the ends thereof is fully magnetized, it will exert a total pull of approximately fifty pounds on the ring 52. This pull is more than sufiicient to compress the four springs 28-28 and to hold the cop tube 3| flush with the end of the tubular member l6 while it is rotated to wind the cop 35 thereon.

The other properties of Alnico No. 5 are set Among other magnetic materials which may be "used in making the permanent magnet 40 are the various Alnico alloys, Cunife (a copper, nickel,

iron alloy), and cobalt steel, which are described in the General Electric catalog and the alloy composed of about 12 cobalt, Vo iron, and 17% molybdenum.

The cop tube 3| is formed in two sections 32-32 in the manner described in order that it tional cop tubes, such as the cop tube 3|, are

described more fully and claimed in my copend- ,ing application Serial No. 97,831, filed June 8, 4949, for Strand Handling Apparatus. jto be understood that the cop tube 3| may be Qconstructed as a one-piece, tubular member havj- It is ing four internal ribs where it is to be used with eccentric type serving machines. Either type of jcop tube may be used readily on theftub ular member |6. r v

Obviously, the winding spindle" and the cop tubes used therewith need not have only four coasting grooves and ribs, but, the number of suchgrooves and ribs may be varied as desired.

What is claimed is:

1. An apparatus for looking a cop tube on a cop winding machine, which comprises an elongated tubular spindle driven by such a machine and having a free end designed to slidably receive and rotate acop tube, yieldable means positioned at the opposite end of the spindle for engaging the end of the cop tube and urging it in a direction in which the cop tube is removed from the spindle, an elongated permanent magnet mounted resiliently within the tubular spindle so that one pole thereof normally extends beyond the free end of the tubular spindle, said magnet being polarized so that its magnetic flux passes longitudinally therethrough, said spindle forming an external path for the magnetic fiux between the poles of the magnet, and an annular member of paramagnetic material designed to be positioned slidably over the pole of the permanent magnet extending beyond the spindle so that it bridges the free end of the spindle and the adjacent pole of the permanent magnet to complete a loW reluctance magnetic circuit which causes the member to be strongly attracted to the free end of the spindle, said annular member being of such size that the outer portions thereof engage the end of a cop tube positioned on the spindle and hold the cop tube on the spindle against the action of the yieldable urging means, whereby when the permanent magnet is moved longitudinally with in the spindle to interrupt the low reluctance magnetic circuit said yieldable means slides the cop in a direction in which it is to be withdrawn from the spindle and disengages the annular member from the end of the spindle.

2. An apparatus for looking a cop tube on a cop in which the tube is removed from the spindle,

a sleeve of non-metallic material secured within the tubular spindle, a cylindrical permanent magnet positioned slidably within the non-magnetic sleeve and polarized so that its magnetic flux passes longitudinally through the magnet, said magnet being designed so that one pole slidably engages the spindle and the opposite pole extends beyond the free end of the spindle so as to form a permanent magnetic field between the free end of the spindle and the pole of the magnet, and an annular member of paramagnetic material positioned over the end of the magnet so as to engage the free end of the spindle and the cop tube and bridge the magnetic field between the magnet and the free end of the spindle whereby the magnetic fiux holds the annular member tightly against the end of the spindle and thereby holds the cop tube on the spindle.

3. An apparatus for locking a cop tube on a cop winding machine, which comprises an elongated tubular spindle driven by such a machine and having its free end provided with a plurality of longitudinal grooves equally spaced about the periphery of the spindle, said. spindle being designed to slidably receive a, tubular cop tube having inwardly projecting ribs which engage the longitudinal grooves and lock the cop tube for rotation with the spindle, a plurality of springpressed stops positioned slidably on the hub of the spindle for engaging one end of the cop tube positioned thereon, said spring-pressed stops being designed to urge the cop tube in the direction in which it is removed from the spindle, a removable retaining ring designed to be fit against the free end of the spindle and having an annular portion extending beyond the periphery of the spindle to engage the end of the cop tube, means positioned in the spindle for causing a magnetic flux to pass longitudinally through the wall of the spindle and form a magnetic field at the free end of the spindle, said ring positioned against the end of the spindle bridges the magnetic field, whereby the magnetic flux powerfully attracts the ring to the end of the spindle and holds the cop tube on the spindle against the action of the spring-loaded stops, and means for altering the external path of the magnetic flux so that the magnetic flux substantially does not pass through the ring whereby the ring may be removed readily from the end of the spindle when it is desired to remove the cop tube from the spindle.

i. An apparatus for looking a cop tube on a cop winding machine, which comprises an elongated tubular spindle secured for rotation by such a machine and having a free end portion provided with a plurality of' longitudinal grooves equally spaced about the periphery of the spindle, said spindle being designed to slidably receive on the free end thereof a cop tube having longitudinal projections engaging the grooves so as to lock the cop tube for rotation with the spindle, a plurality of spring-pressed stops provided on the opposite end of the spindle for engaging one end of the cop tube and urging the cop tube in a direction in which it is removed from the spindle, a removable ring designed to be fit against the end of the spindle and having portions extending beyond the spindle to engage the end of the cop tube positioned on the spindle, and a cylindrical permanent magnet positioned slidably within the tubular spindle and having the portion intermediate the poles thereof magnetically insulated from the tubular spindle, said permanent magnet being polarized so that its magnetic flux passes longitudinally through the magnet, said spindle forming an external magnetic circuit for the flux, said magnet normally forming a permanent magnetic field between the free end of the spindle and the adjacent pole of the magnet, said ring bridges the magnetic field to complete a low reluctance magnetic circuit whereby said ring is attracted strongly to the free end of the spindle to hold flush the cop tube on the spindle against the action of the spring-pressed stops, said permanent magnet being slidably positioned so that it may be selectively moved within the tubular spindle to interrupt the low reluctance magnetic circuit, whereby the ring is removed from the end of the winding spindle by the spring-pressed stops.

5. An apparatus for looking a cop tube on a cop Winding machine, which comprises an elongated tubular spindle having one end secured to such a machine and its free end designed to slidably receive and rotate a cop tube, means positioned at the inner end of the spindle for urging the cop tube in a direction in which the tube is removed from the. spindle, a sleeve of nonmetallic material rigidly secured within the tubular member, a cylindrical permanent magnet slidably positioned within the non-metallic sleeve and having a pole-piece secured on the inner'end thereof which slidably engages the internal surface of the tubular spindle (and a pole-piece mounted on the opposite end thereof and bein of such diameter that it forms an annular air gap between the pole-piece and the inner surface of the spindle, a spring positioned between the inner end of the spindle and the first-mentioned pole-piece for normally positioning the permanent magnet so that the second-mentioned pole-piece extends a predetermined distance beyond the free end of the tubular spindle, an annular retaining ring of magnetic material designed to fit slidably over the second-mentioned polepiece and engage the free end of the spindle, said permanent magnet being polarized so that its magnetic flux passes longitudinally through the magnet and longitudinally through the portion of the spindle positioned across the pole-pieces of the magnet and forms a permanent magnetic field across said air gap, said ring bridges the air gap between the free end of the spindle whereby the magnetic flux attracts the ring to the end of the spindle with sufficient force to hold a cop tube on the spindle against the action of the urging means, and means for moving the permanent magnet against the action of the spring holding it in its normal position so that the second-mentioned pole-piece is withdrawn from the ring, whereby the magnetic flux is substantially diverted from the ring and said rin is disengaged from the end of the spindle by the urging means.

6. An apparatus for locking a cop tube on a cop winding machine, which comprises an elongated tubular spindle of paramagnetic material driven by such a machine and having a free end designed to slidably receive and rotate a cop tube, a permanent bar magnet of relatively high mag- Um I netic strength slidably mounted Within the tubular spindle and having its inner pole in slidable contact with the inner surface of the spindle and its outer pole adjacent to the free end of the spindle, whereby a magnetic flux path is provided which includes the magnet, the paramagnetic spindle and an air gap between the free end of the spindle and the outer pole of the magnet, and a retaining member of paramagnetic material provided With a central aperture and designed to be slidably mounted on the outer pole of the magnet in engagement therewith and to contact the free end of the spindle, thereby bridging the air gap and completing a magnetic circuit which causes the member to be attracted strongly to the free end of the spindle, a portion of the retaining member protruding beyond the outer periphery of the spindle to retain a cop tube mounted thereupon.

7. An apparatus for locking a cop tube on a cop winding machine, which comprises an elongated tubular spindle of paramagnetic material driven by such a machine and having a free end designed to slidably receive and rotate a cop tube, resilient means mounted at the driven end of the spindle for urging the cop tube in a direction in which the tube is removed from the spindle, a permanent bar magnet of relatively high magnetic strength slidably mounted within the tubular spindle and having its inner pole in slidable contact with the inner surface of the spindle and its outer pole adjacent to the free end of the spindle, whereby a magnetic flux path is provided which includes the magnet, the paramagnetic 'spindle'and an air gap between the free end of the spindle and the outer pole of the magnet, and a retaining member of paramagnetic material provided with a central aperture and designed to be slidably mounted on the outer pole of the magnet in engagement therewith and to contact the free end of the spindle, thereby bridging the air gap and completing a magnetic circuit which causes the member to be attracted strongly to the free end of the spindle, a portion of the retaining member protruding beyond the outer periphery of the spindle to retain a cop tube mounted thereupon.

8. An apparatus for looking a cop tube on a cop winding machine, which comprises an elongated tubular spindle of paramagnetic material driven by such a machine and having a free end designed to slidably receive and rotate a cop tube, resilient means positioned at the driven end of the spindle for engaging the adjacent end of the cop tube and urging it in a direction in which the cop tube is removed from the free end of the spindle, a sleeve of nonmagnetic material fixedly secured within the tubular spindle, a

, permanent bar magnet of relatively high magnetic strength slidably mounted within the nonmagnetic sleeve and having its inner pole in slidable contact with the inner surface of the spindle and its outer pole adjacent to the free end of the spindle, whereby a magnetic flux path is provided which includes the magnet, the paramagnetic spindle and an air gap between the free of the spindle and the outer pole of the magnet, and a retaining member of paramagnetic material provided with a central aperture and designed to be slidably mounted on the outer pole or the magnet in engagement therewith and to contact the free end of the spindle, thereby bridging the air gap and completing a magnetic circuit which causes the member to be attracted strongly to the free end of the spindle, a portion of the retaining member protruding beyond the outer periphery of the spindle to retain a cop tube mounted thereupon.

9. An apparatus for locking a cop tube on a cop winding machine, which comprises an elongated tubular spindle of paramagnetic material driven by such a, machine and having a free end designed to slidably receive and rotate a cop tube, a permanent bar magnet of relatively high magnetic strength slidably mounted within the tubular spindle and having its inner pole in slidable contact with the inner surface of the spindle, a spring which normally urges the magnet into a position wherein the outer pole of the magnet is adjacent to the free end of the spindle with a small portion of the outer pole extending therebeyond, a magnetic flux path being provided which includes the magnet, the paramagnetic spindle and an air gap between the free end of the spindle and the outer pole of the magnet, and a retaining member of paramagnetic material provided With a central aperture and designed to be slidably mounted on the outer pole of the magnet in engagement therewith and to contact the free end of the spindle, thereby bridg ing the air gap and completing a low reluctance magnetic circuit which causes the member to be attracted strongly to the free end of the spindle, a portion of the retaining member protruding beyond the outer periphery of the spindle to retain a cop tube mounted thereupon, said cop tube being removable from the spindle by moving the magnet longitudinally from its normal position against the action of the spring sufiiciently to inlease the retaining means.

TILIMAN T. BUNCH.

Bpfir nces Qitaq th fil? 9i th s mm UNITED STATES PATENTS Number 1,236,965 1,261,356

Name Date M1 161 Au 1 19 Brown Apr. 2, 1918 Marquardt Mar. 31, 1925 Martin June 7', 1927 Winslnw July 29, 1941 Number 2,260,055 2,309,963 2,360,928 39,54 2,471,764 2.521 9 Number Name Date Reardqn Oct. 21, 1941 li u eg 2-,--- e 2, 9 Bgeqhlyp Oct. 24, 1944 Plangti 1 Apr. 13, 1948 Miller et a1. May 31, 1949 B1aj Oct. 24, 1950 FOREIGN PATENTS Country Date Great Britain Mar. 27, 1936 G at Brita n May 27, 19.4

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