US3294328A

US3294328A - Thread transporting drive

Info

Publication number: US3294328A
Application number: US395799A
Authority: US
Inventors: Schmidt Richard; Stock Hans Joachim
Original assignee: Franz Morat GmbH
Current assignee: Franz Morat GmbH
Priority date: 1964-09-11
Filing date: 1964-09-11
Publication date: 1966-12-27
Anticipated expiration: 1983-12-27

Description

Dec. 27, 1966 SCHMIDT ETAL THREAD TRANSPORTING DRIVE Filed Sept. 11, 1964 FIG. 7

FIG. 2

FIG. 4

FIG- 6 z ZM at #14 Z 4 fr 3 AME 7 J United States Patent 3,294,328 THREAD TRANPORTENG DRIVE Richard Schmidt, Stuttgart-Vaihingen, and Hans Joachim Stock, Freiburg im Breisgau, Germany, assignors to Franz Marat G.m.h.H., tnttgart-Vaihingen, Germany Filed Sept. 11, 1 364, Ser. No. 395,799 1 Claim. (Cl. 242-47.01)

The present invention relates to a thread transporting drive, and more particularly to an apparatus for rotating a thread transporting roller of the type used in knitting machines for supplying threads at the knitting stations of the machine to the knitting needles.

A thread is guided, or wound in several windings, about a cylindrical transporting roller which has a hard surface of mirror-like smoothness. If slippage of the thread on the transporting roller is desired, the transporting roller is rotated at a very high speed which is a multiple of the highest possible thread transporting speed, and the thread slips on the roller surface when a greater or smaller amount of thread is required for a particular loop knitted by the knitting needles of the machine.

For other knitting operations, the thread must be posi tively transported without any slippage, and in this event, the thread is Wound in several turns about the transporting roller which is rotated at such a speed that the thread is delivered at a constant speed to the knitting needles.

Thread transporting rollers serving this purpose are provided at the several knitting stations of a knitting machine, for example on a circuit knitting machine, and are driven by a gear transmission, friction transmission, or pulley and belt transmission. Such transmissions be tween the prime mover and the thread transporting rollers cause irregularities of the roller motions which have a detrimental effect on the uniform transport of the thread due to the fact that the thread reacts to the smallest differences between frictional forces present between the thread and the surface of the roller. Particularly the necessary uniform tension of the thread is impaired if the rotary speed of the transporting roller fluctuates even slightly, or if the shaft of the transporting roller is caused to webble.

It is one object of the present invention to overcome the disadvantages of known thread transporting drives, and to provide a drive for a thread transporting roller which assures a smooth and uniform rotation of a transporting roller at a constant speed.

Eddy current couplings are known for the transmission of power. Such eddy current couplings assure a very smooth transmission of the rotary motion. However, the eddy current couplings which are used for other purposes provide a driving part and a driven part mounted on a common shaft. In this manner, irregularities and fluctuations of the rotary speed are eliminated due to the effect of the eddy current coupling, but transverse motions of the drive shaft, such as wobbling, are transmitted to the driven coupling part, and if such an eddy current coupling would be used for driving a thread transporting roller, the roller would wobble with the drive shaft so that the thread would not have uniform tension at all times while being transported.

It is another object of the invention to overcome this disadvantage of eddy current couplings, and to provide a drive arrangement for a thread transporting roller in which irregular transverse motions of the drive shaft are not transmitted to the thread transporting roller.

Another object of the invention is to provide a thread transporting roller rotating at a constant speed about a true axis whose position does not change.

With these objects in view, a thread transporting drive according to the invention comprises a first shaft and a second shaft spaced in axial direction along a common axis, and an eddy current coupling including two coupling halves respectively secured to the shafts and connecting the same for rotation.

One of the shafts is a drive shaft which drives the other shaft through the eddy current coupling. The thread transporting roller is secured to the other shaft and due to the fact that the drive shaft and driven shaft are in no way mechanically connected, irregular motions of the drive shaft are not transmitted to the thread transporting roller, or to a thread transported by the same.

One coupling half includes a magnet and the other coupling half includes a good electric conductor so that strong eddy currents are produced. It is advantageous to provide a further member of good magnetic conductivity on the side of the electrical conductor remote from the magnet so that a strong closed magnetic field passing through the electrical conductor is assured.

The thread transporting drive according to the present invention has the advantages of an eddy current coupling, namely immediate establishing of the coupling connection, and a smooth coupling engagement without mechanical parts, without the disadvantages which would be caused by mounting both coupling halves on the same shaft. In this way, a drive connection results which is particularly suited for thread transporting rollers in knitting machines.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claim. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a fragmentary schematic elevation, partially in section, illustrating one embodiment of the invention;

FIG. 2 is .a fragmentary schematic elevation, partially in section, illustrating another embodiment of the invention;

FIG. .3 is a fragmentary schematic elevation, partially in section, illustrating a third embodiment of the invention;

FIG. 4 is a schematic side view taken on line 4-4 in FIG. 3;

FIG. 5 is a fragmentary schematic elevation, partially in section, illustrating another embodiment of the invention; and

FIG. 6 is a sectional view taken on line 66 in FIG. 5.

Referring now to the drawing, and more particularly to FIG. 1, a drive shaft 1 is driven by the drive means of the knitting machine, not shown, through a pair of

meshing bevel gears

3 and 2. Bevel gear 2 is secured to shaft 1, and bevel gear 3 is coaxial with the main axis of a circular knitting machine and has a great diameter, so that a bevel gear 2 can be provided at each knitting station spaced around the periphery of the knitting machine. It will be understood that a thread transporting drive of any embodiment of the invention is provided at each knitting station.

Drive shaft 1 is mounted in a hearing In to which a horseshoe magnet :is secured. Magnet 6 has two terminal poles disposed adjacent to a circular disc 7 which consists of a material which has a high electric conductivity. Dis 7 is secured to a second shaft 8 mounted in a bearing 14 coaxially with a drive shaft 1 and axially spaced from the same. A transporting roller 10 is secured to shaft 14 and has a smooth cylindrical surface about which a thread 20 is looped in at least one turn. Intermediate the electrioally conducted disc 7 and transporting roller 10, another circular disc 9 consisting of a magnetizable material of high magnetic conductivity is secured to shaft 8 for rotation therewith.

Discs

7 and 9 may actually be secured to the transporting roller 10, and disc 9 may be integral with transporting roller 10, in other words, transporting roller '10 may consist of a highly magnetizable material.

The magnetic field of magnet 6 passes through the magnetizable material of member 9 and permeates the electrically conductive disc 7 so that eddy currents are produced in disc 7 during rotation of magnet 6 and produce a magnetic torque by which transporting roller 10 is rotated in synchronism with magnet 6 so that thread 20 is transported. The magnetizable disc 9 may be omitted but improves the efiiciency of the coupling.

The embodiment of FIG. 2 includes a pulley 4 secured to drive shaft 1 and driven by belt '5 from the drive means of the knitting machine, not shown. A horseshoe magnet 6 is secured to shaft .1 and rotates with the same. Shaft 1 is extended between the legs of the magnet, and carries a core member 11 of cylindrical shape which rotates at the same speed as magnet 6 and consequently has its ends always located opposite the poles of magnet 6 and forming two terminal gaps with the same through which the magnetic field lines pass. A pot-shaped member 12 consisting of a material having good electric conductivity is secured to a shaft 13 spaced in axial direction from shaft 1 along a common axis. A bearing 14 supports shaft 13, and a thread transporting roller 15 is secured to shaft 13 on the other side of. bearing 14. The cylindrical portion of the pot-shaped member 12 is located in the two terminal gaps between the end of core member .11 and the poles N and S of magnet 6. When shaft 1 is driven by the transmission 4, in synchronism with the operations of the knitting machine, magnet 6 rotates together with core member 11, and the magnetic field passing through the two gaps and core member 11 produces eddy currents in the pot-shaped member 12 so that a magnetic torque develops which couples member 12 to the

magnetic means

6, 11 whereby shaft 13 and transporting roller 15 are driven in synchronism with shaft .1 to transport a thread, not shown, wound about the cylindrical surface of roller .15. In a modified embodiment transporting roller 15 is omitted, and the cylindrical surface of pot-shaped member 12 which projects from the magnetic means transports the thread which is wound about the cylindrical portion of member 12 as shown in FIG. 1. The axial length of the cylindrical part of member 12 may be increased for this purpose, as compared with the illustration of. FIG. 2.

In the embodiment of FIG. 3, drive shaft 1 is driven from the knitting machine as described with reference to FIGS. 1 and 2 and carries a magnetic bar 16. The driven shaft 18 is mounted in a bearing 14 and fixedly carries a pot-shaped member 19 which consists of a materialhaving high magnetic conductivity so that the magnetic field lines pass from the poles of magnet 16 through the magnetizable member .19, as indicated by broken line 611. A pot-shaped member 17 consisting of a good electrical conductor is fitted into the interior of the pot-shaped member 19 and secured to the same and to shaft 14. Consequently, the magnetic lines of force 601 permeate the portions of member 17 located opposite the poles of magnet 16 and produce eddy currents in the same during rotation of shaft 1 with magnet 16. The magnetic torque developed in this manner couples member 17 to magnet 16 so that shaft 18 is rotated in synchronism with shaft 1. A thread, not shown, is wound about the smooth cylindrical surface of member .19 which serves as transporting roller. However, it is also possible to secure a transporting roller to shaft 18, as explained with reference to FIG. 2.

In the embodiment illustrated in FIGS. 1-3, the elements rotating with the driven shaft, namely the transporting roller and the driven parts of the eddy current coupling must be dimensioned in such a manner that the moment of. inertia is sufficient in relation to the magnetic coupling force to compensate and equalize forces transmitted from thedriven shaft or caused by the thread. The parts rotating with the driven shaft and moving in synchronism with the transported thread should have a substantial mass to equalize fluctuating forces. This can be accomplished by mounting the heavier parts of the magnetic coupling on the driven shaft.

In the embodiment of FIGS. 5 and 6, the drive shaft 1 carries only a pot-shaped member 23 which consists of a material having high electric conductivity. The driven shaft 24 carries the heavy magnet 21 which has its ends located spaced a short distance from the cylindrical inner surface of member 23. The driven shaft 24 also carries pot-shaped member 22 which consists of a material having high magnetic conductivity. The cylindrical part of member 22 surrounds the cylindrical part of member 23 and is spaced from the same by an annular gap. The magnetic field of magnet 21 is closed through pot-shaped member 22 as indicated by broken line 6a and the magnetic field lines permeate the cylindrical portion of potshaped member 23. During rotation of shaft 1 with member 23, the eddy currents produced by magnet 21 in member 23 produce a coupling torque by which magnet 21 and pot-shaped member 22 are coupled to the rotating member 23 whereby shaft 24 is driven. In the embodiment of FIGS. 5 and 6, the two heavier parts of the eddy current coupling are mounted on shaft 24, while in the embodiment of FIGS. l-3 the heavy magnet is mounted on the drive shaft 1. Due to the great inertia of

parts

21, 22, 24, fluctuations in the rotary speed are equalized, and a thread wound about the outer cylindrical surface of pot-shaped member 22 is transported at a uniform speed. It is, of course, also possible to secure a transporting roller to shaft 24 on the right side of bearing 14, as viewed in FIG. 5.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of thread transporting drives differing from the type described above.

While the invention has been illustrated and described as embodied in two terminal coupling halves of an eddy current coupling mounted on two terminal spaced coaxial shafts, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claim.

What is claimed as new and desired to be secured by Letters Patent is:

A thread transporting drive comprising, in combination, a first shaft and a second shaft spaced in axial direction along a common axis; drive means for driving said first shaft; and an eddy current coupling including a magnet secured to said first shaft for rotation therewith, a potshaped transporting roller having a magnetizable cylindrical portion adapted to be engaged by a thread and surrounding said magnet so as to form two gaps with the same, and a circular bottom portion having a center secured to said second shaft for rotation therewith, and a pot-shaped member consisting of a material having high electric conductivity fitted into the interior of said potshaped transporting roller and having a cylindrical portion located in said gaps so that a magnetic field passing through said transporting roller permeates said cylindrical 5 portion of ,said pot-shaped electrical conductive member whereby said first and second shafts are coupled to each other in such a manner that irregular motions of said first shaft are not transmitted to said thread transporting roller and to a thread transported thereby.

References Cited by the Examiner UNITED STATES PATENTS 1,892,554 12/1932 Kellogg. 2,902,612

FOREIGN PATENTS FRANK I. COHEN, Primary Examiner.

9/1959 Whearley 310105 10 W. S. BURDEN, Assistant Examiner.