System for producing wound warps

Wound warps are made by pulling a multiplicity of warp filaments off respective supplies and winding them around a warp beam by rotating the warp beam while pressing the filaments against the beam with a predetermined packing force by a packing roller. The packing roller is deflected outward from the beam by the filaments as same are wound on the beam, and an output is produced representing the rotation of the beam. Another output is derived from this outward deflection of the packing roller that represents the rectified length of the filaments wound on the beam. The outputs from a first wound warp are used as set points, and the outputs from a subsequent wound warp are used as actual values and compared to the set points. The force of the packing roller is varied such that the actual values of the subsequent wound warp are made generally equal to the set points.

FIELD OF THE INVENTION

The present invention relates to a warping system, that is a system for winding a multiplicity of parallel warp filaments, e.g. threads or yarns, onto an elongated warp beam. More particularly this invention concerns a method of and apparatus for producing a plurality of wound warps with filaments of identical length and diameter.

BACKGROUND OF THE INVENTION

In a weaving mill it is necessary to have or produce for the looms warp beams where all the warp threads or yarns are of identical length from one beam to the next. It is also important that all the beams of a given production run have the same diameter, the result being that the filament density is the same on all the beams. Thus it is in general known to monitor the length wound on the beam and the number of revolutions the beam made to wind up this length for a first model wound warp, and then to use these values as set points comparable to actual values determined during the winding of subsequent beams.

In German 32 06 272 of Koslowski the number of beam revolutions and the length of wound filament is continuously monitored, with respective set-point outputs produced and recorded for the model wound warp, that is the first of a series of wound warps that are supposed to be identical. The actual values of the number of beam revolutions and the length being wound in subsequent cycles for copies are compared to the respective set points and correction are made by changing the warp-beam rotation rate, acting on thread brakes in a filament-supply creel, or braking a packing roll so bring the actual values back to the respective set points. The filament length is determined simply by passing the entire warp sheet over a measuring roller coupled to rotation-detecting and -measuring sensor.

Another such system shown in EP 1,219,738 of Hane the beam rotation and the warp length are monitored to determine how much warp is wound up with each revolution of the beam, and this value is stored. The same values for copies are compared with the stored values to generate a difference signal. The tension in the warp is varied to keep the actual-value signals identical or close to the set-point signals, that is to reduce the respective difference signals to the smallest possible levels. When the warp filaments are elastic so that they can stretch, this is a problem. The actual-value of the filament length being wound is determined by passing the incoming warp sheet over a measuring roller, or by pressing a measuring roller against the wound warp on the warp beam.

There are substantial problems with these systems at the start and end of each winding cycle, that is the winding of a single copy beam. Excessive braking of a rotating beam can produce so much slack as to make the wound warp unusable, and excessive acceleration can tension the filaments enough to break or stretch them.

Accordingly, German 36 04 790 of Guillot describes a system where the density of the copies is controlled by varying the radial pressure exerted on the warp being wound by a packing roller. The actual value for the filament length is determined by a separate measuring roller also radially engaging the warp being wound. With this system the diameter of the warp being wound is used to determine the filament length for a given rotation of the beam, producing a partial length that is stored and compared with that of subsequent copies, with the packing roller pressure varied to produce uniformity. Such a system therefore has both a packing roller and a length-measuring roller.

In U.S. Pat. No. 5,257,462 of Butterman the warping system has a packing roller bearing upon the warp being wound and mechanically connected with a displacement detecting transducer that emits measurement impulses, a beam-driven shaft encoder that emits a predetermined number of calculation impulses for each revolution of the beam, and a computer that calculates the partial lengths of the warp layers or laps from the measurement impulses and the calculation impulses. The displacement-detecting transducer is movably or slidingly interengaged with an elongated linear member in the form of a toothed rack hinged so that a projection of one end always intersects the longitudinal axis of the lap beam. A correction read-out is calculated from the diameter of the axle of the lap beam and the position of the point of interengagement of the elongated linear member with the displacement detecting transducer through the pressure point of the packing roller bearing upon material wound upon the lap beam and the number of rotations of the lap beam. Such a system can calculate the total filament length and the wound density, but is quite complex.

OBJECTS OF THE INVENTION

It is therefore an object of the present invention to provide an improved system for producing multiple identical wound warps.

Another object is the provision of such an improved system for producing multiple identical wound warps that overcomes the above-given disadvantages, in particular that is fairly simple, that is particularly safe during the starting and ending stages of a winding operation, and that can produce a series of wound warps that are of identical length and density.

SUMMARY OF THE INVENTION

According to the invention wound warps are made by pulling a multiplicity of warp filaments off respective supplies and winding them around a warp beam by rotating the warp beam while pressing the filaments against the beam with a predetermined packing force by a packing roller. The packing roller is deflected outward from the beam by the filaments as same are wound on the beam, and an output is produced representing the rotation of the beam. Another output is derived according to the invention from this outward deflection of the packing roller that represents the rectified length of the filaments wound on the beam. The outputs from a first wound warp are used as set points, and the outputs from a subsequent wound warp are used as actual values and compared to the set points. The force of the packing roller is varied such that the actual values of the subsequent wound warp are made generally equal to the set points.

With the inventive system the outward deflection of the packing roller is used to determine the rectified length of the filaments wound on the warps, eliminating the need for a separate roller assembly bearing radially against the warp being wound and provided with its transducer. This represents a substantial simplification of the apparatus, and produces a plurality of wound warp beams of identical density, diameter, and filament length.

In accordance with the invention the density of the wound warp is directly determined by the outward deflection of the packing roller. This means of determining the filament length is more accurate than simply counting revolutions of a measuring roller bearing radially on the warp being wound or over which the warp passes between the beam and the supplies where slip is inevitable. Determining the filament length from the deflection of the packing roller is extremely accurate. This is due to the fact that the deflection of the packing roller closely corresponds exactly to the actual radius of the warp being wound more accurately, as a result of the packing force, than a simple sensor roller riding on the warp.

According to the invention outward deflection of the packing roller is braked to vary the force exerted by the packing roller on the warp being wound. Such braking allows the packing force to be set very accurately, simply by applying the brake more forcibly to increase the packing force and vice versa.

When the supplies are new the packing force is increased according to the invention by a predetermined compensating force, typically between 5% and 50% (preferably 10% to 30%) of the normal packing force. Without this step, it is necessary to provide separate means for controlling warp-filament tension, as otherwise the filament tension increases as the spools or packages from which they are drawn get smaller. With the system of the invention the extra packing force applied at the start, when the tension is inherently low, is compensated out. This inventive step is important when using new spools for producing a plurality of wound warps, where the starting pressure is the actual packing pressure is used. It is particularly advantageous at the start of a winding operation when the starting packing pressure is standardized, that is corresponds to the packing pressure used in an operation with a constant packing pressure and or average to light thread tension. In this manner it is not necessary to provide the creel, that is the yarn supply, with complex thread brakes to achieve the desired tension and density.

In accordance with the invention the packing force is adjusted during winding of subsequent warps by using interpolated set points. The control device, when of the SPS type, typically has limited memory. Using interpolated set points makes the regulation particularly sensitive and creates wound warps of particularly uniform density.

The packing roller according to the invention is mounted on one or two arms pivotal about an axis offset from the warp-beam axis. The packing-roller displacement is therefore along an arcuate path and is detected by a sensor assembly comprising a rod projecting past the packing roller and a position sensor carried on the roller, riding on the rod, and responsive to a position of the roller along the rod. The sensor can be a simple rotary unit having a pinion meshing with teeth formed on the edge of the rod, as in above-cited U.S. Pat. No. 5,257,462. This toothed rod is pivoted at one end.

SPECIFIC DESCRIPTION

As seen inFIG. 1a warp1comprised of a multiplicity or sheet of parallel and coplanar filaments is pulled through an upstream guide4from a creel3holding a multiplicity of supply bobbins or packages with respective filament brakes and is passed through a standard guide comb5and over a deflecting roller6to tangentially wind up on a warp beam7. A drive illustrated schematically at54rotates the beam7about its axis12in a direction55. The beam7is cylindrical, has an outside diameter d, and is provided on its ends with flanges or plates8of circular shape extending perpendicular to the axis12and having an outside diameter D substantially greater than the diameter d. Ends of the beam7are supported in upright end plates15and16(FIG. 3) of a machine frame17(FIGS. 2 and 4).

The warp1is wound up on the beam7to a radius r which can be as small as d/2 and as large as D/2. The path of the warp1is shown in a dot-dash line for a radius r=d/2 and in solid lines for a radius r=D/2. The goal of the present invention is to form a first so-called model beam and then, in subsequent cycles, produce copies that are substantially identical.

To this end a packing or compacting roller9of cylindrical shape and centered on an axis13parallel to the axis12is carried on the outer ends of a pair of parallel arms10(see alsoFIG. 3) whose inner ends are mounted in the plates15and16for pivoting about an axis11parallel to the axes12and13. Thus, as the roller9is pushed outward from an innermost position shown in dashed lines in which r=d/2 to an outer position shown in a solid line in which r=D/2, the axis13of the roller9moves through an arc14here shown to have a starting point on a plane P extending through the axis12and through the axis13in its outermost position.

As also shown inFIGS. 2 and 3the roller9carries a rotary transponder18having a gear meshing with a rack bar19pivoted on the frame plate15at an axis20parallel to the axes11and12and slidable in a block21pivoted at22at the axis13of the roller9and carrying the transponder18. Thus, as the roller9moves in the arc14between its end positions, the transducer18will emit on a line25a series of pulses constituting an output shown at24that indicates the position of the axis13along the arc14relative to the axis12. The axis20is positioned in the plane P and so is the rack19in the two end positions of the roller9. When at its maximum deflected position in a half-way position, the rack19extends along a line23defining a very small acute angle with the plane P.

FIG. 1also schematically illustrates that another such transponder or sensor26is provided at the axis12to produce in a line28an output27that represents the angular position or rotation (and possibly also the rotation direction) of the beam7. Thus the revolutions U are represented by the output27and the radius r by the output24.

FIGS. 3 and 4show how a shaft32carrying the two arms10and journaled in the plates15and16is attached at one end to a brake29. More particularly, this shaft32carries at one end a hub29from which extends a 60° sector plate30having an edge31engaged by a pair of brake shoes33both pivoted on a mount39carried on the plate15and having outer ends34that can be urged apart by a stem36of a pneumatic actuator35supplied via a conduit37from a pressure-regulating valve38in turn supplied via a conduit53with air under pressure from a source illustrated schematically at56. Thus as pressure in the actuator35increases, the jaws33grip the plate30more aggressively and more forcibly brake rotation of the shaft32and angular displacement of the roller9. Since as the beam7rotates and winds up the warp11, the radius r has to increase, such braking action has the effect of compacting the layers or laps of warp on the beam7.

An actuator shown schematically at57inFIG. 1is provided for moving the roller9into the innermost position at the start of a winding cycle and for canceling out the weight of the roller9. In addition a magnetic brake58is provided for impeding rotation of the roller9.

FIG. 4shows an SPS control assembly2having a microprocessor40with a pair of inputs receiving the outputs24and27respectively corresponding to the position of the axis13relative to the axis12and the rotation of the beam7. A memory41has an input46for receiving data from a model warp being wound and an output47for feeding out this data as a set point to the processor40for comparison with the respective actual-data inputs24and27of subsequent copy warps.

The processor40has an output line48connected to a controller42whose output line50is fed to an output unit43also receiving on an input51data from an input unit44, e.g. a keyboard. Another output line49from the processor40leads to a display45that shows the machine operator the status of the system. An output52from the output unit is connected to the valve38. Converters are provided where necessary to adapt the various signals.

The function of the control assembly2is to control the density of the warp being wound and determine the rectified length of its filaments. To start with a model wound warp is created by securing the free ends of the warp to an empty warp beam7and then pressing the roller9radially inward against it. The brake29is set by the unit2at a predetermined clamping pressure and the cylinder57is released, leaving the roller9bearing with a force F(x) against the warp1on the warp tube7. The drive54is then started so that the radius r of the warp1being wound increases, as does a deflection x of the roller9. As this takes place the outputs25and27are stored in the memory41. The operation continues until r=D/2, whereupon the warp1is cut upstream of the finished wound warp, the actuator57retracts the roller9, the beam7is switched for an empty one that the warp1is applied to, and the roller9is moved back inward.

In order that the second and subsequent wound warps are identical to the first model one, the actual-value signals24and27are used as set points. Thus as each subsequent warp is wound, the pressure regulated by the valve38is changed such that any difference between new actual-value signals and the stored set-point signals is eliminated or reduced to something nominal. More particularly, any variation is converted into a pressure differential ΔF fed to the output unit43. This value of ΔF is compared with the current pressure F(x−1) of the force previously stored in the unit43, and is added up, F(x)=F(x−1+ΔF and fed to the valve. In this embodiment the values24corresponding to the deflection x and the values27for the revolutions U of the beam7are stored as tables.

Since the memory41can only hold a limited number of set points, the processor40interpolates set points for a large number of actual values and feeds the result to the controller42. In this manner the number of control cycles is substantially greater than the number of stored set points.

The starting value of the pressure for a model beam with new filament supplies is set at the standard force Fb plus a compensating force Fa, or F(x0)=Fb+Fa. The standard force Fb and the compensating force Fa are fed by the input unit or keyboard44to the output unit43. With new filament supplies at any stage the actual pressure F(x−1) used at the start is increased by Fa and then further exploited as described above.

In an example using cotton, a standard packing force of 3000 N is used, with a compensating force of 20% or 600 N. When d=150 mm and D 1400 mm, the number of revolutions is recorded each time the roller9shifts through 10 mm, so that 125 readings are taken.

Winding is controlled at frequent intervals. Regulation starts when in a control interval there is a minimal deviation of the actual value, here the number of revolutions U of the beam7, for a given deflection x of the roller9. On such deviation, the set point, here the packing force, is increased or lowered by a constant amount ΔF0. The control interval here is 3 s, the minimum deviation in number of revolutions is 5 revolutions, and the standard correction ΔF0is 0.5% of the standard force Fb, here 15 N. This value is fed as a voltage signal between 1 V and 10 V to the valve38.

With new filament supplies instead of increasing the actual packing force F(x−1) by the compensating force Fa, a greater compensation can be effected. e.g. a multiple of ΔF+or am amount ΔF(ΔU) proportional to the deviation from the set point, here the number of revolutions U per deflection x. This is an alternative method for compensating out smaller filament tensions with new supplies. In any case, however, the starting force has to be increased.