Winding – tensioning – or guiding – Helical or random winding of material – Distributing material along the package
Reexamination Certificate
1999-12-20
2001-11-06
Mansen, Michael R. (Department: 3653)
Winding, tensioning, or guiding
Helical or random winding of material
Distributing material along the package
C242S481200, C242S483900, C310S017000, C310S019000, C310S021000, C318S127000
Reexamination Certificate
active
06311919
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a yarn guide and, more particularly, to a yarn guide for the traversing delivery of a yarn to a rotationally driven takeup bobbin for creating a cross-wound bobbin, or cheese, in a bobbin winder of a textile machine as generically defined by the characteristics of the preamble to the first claim.
BACKGROUND OF THE INVENTION
To make textile bobbins, it is necessary in principle on the one hand to make the bobbin rotate and on the other to traverse the traveling yarn, which is being wound onto the rotating bobbin, along the bobbin axis. If the yarn is traversed very slowly, a bobbin with highly parallel windings is created. If such a bobbin is meant to have a relatively large volume and to have flat face ends disposed substantially at right angles to the bobbin axis, then boundary disks are required on both ends of the package. These boundary disks are not necessary if the yarn is traversed fast enough to produce a cross winding. High winding speeds thus require a very high traversing rate as well.
Drive means such as belts, oriented parallel to the bobbin axis, can be used for this purpose. European Patent Disclosure EP 0 311 827 A2 describes one such yarn guide in which the belt is driven by means of a microprocessor-controlled stepper motor. High traversing speeds can be attained and the yarn guide can be controlled relatively precisely.
So-called shogging rollers are also very widely used to create the traversing motions; in high-speed bobbin winders, they often simultaneously utilized to provide the circumferential drive for the cheese. However, the laying angle dictated is always the same, regardless of the bobbin fullness, and at certain rpm ratios between the bobbin and the drive roller, so-called ribbon windings occur, which later present considerable unwinding problems. The prior art therefore describes many so-called ribbon breaking methods.
To create a predetermined winding pattern, such as a precision or graduated precision winding, the bobbin must be driven separately from the yarn guide. This can be done, among other ways, by spacing the aforementioned shogging roller apart from the takeup bobbin, which is driven separately. As a rule, a yarn guide then slides in the shogging groove. This system has disadvantages because of inertia.
So-called finger yarn guides have also long been known (for instance from published, examined German Patent Application DE AS 11 31 575 and published, unexamined German Patent Application DE OS 15 60 360), in which a finger- or fork-like yarn guide is pivotable about an axis disposed substantially perpendicular to the takeup bobbin axis. Instead of the conventional mechanical drive mechanisms described therein, electromechanical drive mechanisms have meanwhile been proposed for these fork-like yarn guides of the kind suggested for instance in European Patent Application EP 0 808 791 A2 or in European Application EP 0 838 442 A1, which representatively describe this basic type of drive. However, these references merely mention that these drive means are electric motors. It can be assumed that either the rotary motion of the motor is converted into a pivoting motion of the yarn guide finger, via gear means that increase the inertia of regulation, or else a motor is used that drives the yarn guide finger directly, and in the case of a stepper motor generates the desired pivoting angle via a predeterminable number of steps. Given the high speed and the high direction-reversal frequency, stepping errors can occur, which then lead to a permanent shifting of the drive mechanism and consequently to winding flaws.
In conventional electric motors, such as electronically commutated motors, it is also difficult on the one hand to generate a required high moment at the turning points but on the other to keep the mass of the rotor, which executes only a pivoting motion, small enough that the resultant mass inertia does not further increase the required moment.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to improve the aforementioned electromechanical type of drive for a traversing yarn guide in a bobbin winder.
This object is attained according to the invention by a yarn guide for imparting a traversing motion to a yarn in a textile yarn winding operation. In such an operation, the yarn is being delivered to a rotationally driven takeup bobbin. The traversing motion creates a cross-wound bobbin, or cheese. According to the present invention, the yarn guide comprises a fork-like guide element, pivoting means for pivoting about a pivot axis oriented substantially perpendicular to the axis of the takeup bobbin, and an electromagnetic mechanism. The electromagnetic mechanism comprises an air gap, a plurality of magnets disposed along the air gap, a plurality of yokes and at least one electrical coil extending into the air gap. The magnets are disposed along the air gap and generate magnetic field lines which extend in a substantially perpendicular direction through the air gap. Current may be supplied to the electrical coil, which is movable along the air gap.
The invention achieves a number of advantages. According to the invention, a relatively high magnetic flux density can be achieved inside the air gap, and the losses, given a small air gap width and adequate dimensioning of the yokes, which have a low magnetic resistance, are low. By supplying current to the coil, which is located in the region of the magnetic field lines, the moment required to deflect the yarn guide is attained.
The dimensioning of the coil is closely related to the adaptation to the gap width of the air gap according to the invention, through which the magnet lines flow. The spacing of the windings of the coil that extend into the air gap from the pivot axis of the yarn guide determines the magnitude of the moment that can be attained by the drive mechanism. This moment is great in proportion to the mass inertia of the coil. The other parts of the body involved in the oscillation can be made from very lightweight material and need merely have the stability required for the incident forces, so that low mass inertia is obtained.
The air gap, and thus all the elements for generating the magnetic field, need merely extend over the pivoting range of the electrical coil, which corresponds to the maximum settable traversing stroke of the yarn guide. The engineering expense is thus limited accordingly. Similarly, only one electrical coil is needed, which during the oscillation moves up and down along the suitably dimensioned slip. As previously noted, it is of particular importance that the elements involved in the pivoting motion have the least possible mass, since at the region at the center of the oscillation of the yarn guide, considerable angular accelerations must be achieved and accordingly, given high mass inertia of the oscillating parts, very high moments must be imposed. It must be taken into account here that in the manufacture of cheeses or bobbin winders, yarn guide oscillation frequencies may range up to 30 Hz.
To generate the magnetic field, it is enough for magnets to be disposed on one side of the air gap. A yoke is then disposed directly on the opposite side of the air gap from the back side of the magnet assembly. The magnetic field lines thus for the most part extend within good magnetic conductors. The air gap can be made small, as already described above, so that the magnetic resistance is further limited.
However, according to another aspect of the invention, it is also possible to dispose magnets on both sides of the air gap, as a result of which the magnetic flux density can be further increased and greater moments can be attained.
In another aspect of the invention, the magnets can either be permanent magnets, which need not be connected to a power supply, or electromagnets, with which a higher magnetic flux density, and thus even greater capacity, are attainable.
In yet another aspect of the invention, the magnets may be disposed in a first magnet region and a second magnet re
Flamm Franz-Josef
Hermanns Ferdinand-Josef
Sturm Christian
Kennedy Covington Lobdell & Hickman LLP
Mansen Michael R.
W. Schlafhorst AG & Co.
LandOfFree
Yarn guide for the traversing delivery of a yarn to a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Yarn guide for the traversing delivery of a yarn to a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Yarn guide for the traversing delivery of a yarn to a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2569014