Electricity: motive power systems – Motor load – armature current or force control during...
Reexamination Certificate
2002-07-22
2004-12-07
Martin, David (Department: 2837)
Electricity: motive power systems
Motor load, armature current or force control during...
C318S432000, C318S434000, C318S566000, C242S614000, C242S614000, C242S614000, C242S413100, C242S413200
Reexamination Certificate
active
06828743
ABSTRACT:
This application claims the benefit of Belgian Application No. 2001/0496 filed Jul. 20, 2001.
BACKGROUND OF THE INVENTION
This invention relates to a method and a device for controlling a winder, where the winding torque is controlled as a function of the desired tractive force in the material to be wound.
This invention likewise relates to a winder comprising a winding body for winding a material, a drive device for driving this winding body and a device for controlling the winder, which is provided for automatically controlling the winding torque of the winder as a function of the desired tractive force in the material.
More particularly, this invention relates to such a method and device for controlling a device for winding a textile material, more particularly for winding a pile tissue, and more particularly to such a device which is installed in the vicinity of a weaving machine to wind a textile material, during its being woven on the weaving machine. A winder for such an application also falls within the scope of the present invention.
It is known that when winding a flexible product (for instance a fabric, paper or a sheet material on a winding cylinder, the driving torque must increase as the winding diameter increases, in order to exert a constant tractive force. To achieve this objective special winders were developed equipped with a controlling system provided for to measure the winding force or the winding torque of the winding cylinder at a certain difference between the measured value and a desired value in order to accomplish an adjustment of the winding torque, so that this difference is annulled or reduced. These systems operate with short cycle times and powerful speed-torque controls to perform the winding at high winding speed at a high precision. When starting and stopping the speed and the winding torque are carefully regulated. These systems require a control system which operates in a closed loop and which comprises corresponding position localizers for a dancer roll and torque and power sensors in the drive. The sensors find a difference and the control system must annul or reduce this difference. Such systems operate reactively.
These devices have the disadvantage of being rather expensive and because of the necessity of a dancer roll they take up quite some space. With a number of ranges of application (for instance a winder for a weaving machine) there is not enough space available for a dancer device. Moreover the winding speeds of the woven fabric are very low (in the order of some cm per minute) with fabrics having a high weft density up to some dozens of cm/min for fabrics having a low weft density), because of which the expensive reactive regulating systems are not justified from an economical point of view.
Therefore simple, solid and yet affordable systems are often chosen for winding devices for weaving machines. In known winding devices for weaving machines torque motors or rotating field magnets are used, developing a torque applied to the winding spindle of the winding device via a high efficiency gear transmission. The torque developed by the torque motor is proportional to the square of the voltage applied to the motor. This voltage is adjusted by means of a regulating variable transformer, which is manually adjusted at the beginning of the winding process and which is readjusted periodically during the weaving process. Such drives are very simple, solid, free of maintenance and cheap.
However, these known winders also have some disadvantages. The tractive force in the fabric during winding must be adapted to the fabric characteristics: delicate fabrics are wound with a low tractive force in order to prevent the fabric from getting creased, heavier fabrics are wound with a stronger winding force to avoid the fabric from turning with the pulling cylinder or dragging on the floor under the influence of its heavy own weight.
As the fabric itself is thicker, readjusting as a function of the winding diameter is needed more frequently between the initial and the final diameter. Moreover, the torque at a greater final diameter must also be relatively higher for a same fabric length than for a thin fabric.
Winding up pile fabrics is still more delicate because crushing the pile by winding the fabric too tightly because of too strong a tractive force in the fabric should be avoided. On the other hand, winding the fabric too loosely is not good either because the cylinder will hang too one-sidedly on the part to be wound up and therefore will leave tracks on the pile surface. Because of the pile height the fabric is rather thick and an accurate readjustment of the torque by hand during weaving should be carried out more frequently.
Therefore, this system of manual readjustment of the winding torque during the weaving process includes certain dangers as the quality of the fabric is concerned and the quality of the winding therefore requires a rather high intervention of the operators. Moreover, much time is lost by redefining the best position of the variable transformer to wind a certain fabric having a certain winding diameter under the best circumstances. This readjustment is still more complicated because of the fact that readjusting by means of a variable transformer is not functioning linearly.
SUMMARY OF THE INVENTION
The purpose of the present invention is to provide for a method and a device to control a winder by means of which the driving torque of the winding element can be efficiently controlled as a function of a desired tractive force in the material that is wound, and by means of which the disadvantages mentioned above are remedied.
This purpose is achieved by applying a method according to this invention and by providing a device with which during the winding process repeatedly:
is calculated which value a quantity (V
i
) influencing the winding torque (T
w
) has to adopt in order to obtain the desired tractive force (F
w
), whereas in each calculation of the value of said quantity (V
i
) a winding torque to be developed is assumed which is determined from the desired tractive force (F
w
), the initial winding diameter (d
0
), the thickness (S
w
) and the winding length (l
w
) of the wound up material, and an adjustment of the said quantity (V
i
) is made, in which the calculated value is used as an objective value.
Therefore, the quantity to be regulated is now pro-actively calculated, for instance accordingly to a mathematical model as a function of a number of parameters. In this manner, a material (for instance a fabric) may be wound up with a tractive force that can be adjusted to an ideal value during the winding process without any manual intervention. This value can be tuned to the characteristics of the material. In this way, a fabric can be wound up during the weaving process while the tractive force is kept at a constant value. This method can be implemented with a control device needing no dancer roll that takes up relatively little space and which is simpler and less expensive than the control devices in existence.
Once experienced which tractive force is best to wind up a material, the tractive force is stored (for instance in a computer file) and errors or problems caused by wrong adjustments are avoided. In the case of a weaving machine, this tractive force can be stored in a file containing fabric characteristics in the control system of a weaving machine. In this manner quality errors such as creasing, crushing of the pile (of a pile fabric) fabric rolls of cloth wound too tight or too loose, etc. are avoided.
In a preferred method and a preferred device, the winding torque to be developed is determined by means of the following formula
T
w
=0.5*
F
w
*√{square root over (4*
s
w
*l
w
/&pgr;+d
0
2
)}
Preferably, a method is applied and a device provided in which the said quantity is a control voltage (Vi) to be applied to the drive gear or control device, whereas this control voltage is calculated by means of a formula obtained by equating the winding torque (T
w
) to be developed, expressed as
Creighton Wray James
Martin David
N.V. Michel Van de Wiele
Narasimhan Meera P.
Smith Tyrone
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