US2147514A - Manufacture of artificial silk - Google Patents

Description

Feb. 14, 1939. J. H. BARNES MANUFACTURE OF ARTIFICIAL SILK Filed April 30, 1936 2 Sheets-Sheet 1 Feb. 14, 1939. J. H. BARNES 2,147,514

MANUFACTURE OF ARTIFICIAL SILK Filed April 50, 1936 2 Sheets-Sheet 2 Patented Feb. 14, 1939 UNITED STATES MANUFACTURE OF ARTIFICIAL SILK Joseph H. Barnes, New Castle, Del., assignor to Delaware Rayon Company, New Castle, Del., a corporation of Delaware Application April 30, 1936, Serial No. 77,262

3 Claims.

This invention relates to the art of manufacture of artificial silk and the like and in particular to a process and apparatus for forming freshly spun cakes or packages of artificial silk 5 and the like, the threads of which will be improved by having more uniformity in characteristics such as dyeing, strength, stretch, and denier.

In the manufacture of artificial silk and the like by the usual pot or bucket method of spinning, a constant and uniform quantity of cellulosic solution is forced through a spinnerette into a coagulating bath in which a thread is formed. This thread is then drawn out of the bath at a constant rate by a constant speed godet wheel. The thread is then collected in a pot or bucket. The thread is allowed to continue to collect in this bucket until a cake builds up to a thickness which is considered sufiicient. The time required to build up the cake to the desired size is called the dofiing time or dofiing cycle.

If the characteristics of the thread collected on the inside of the cake are studied carefully by accurate methods and instruments and compared with the characteristics of the thread coming from the outside of the cake by the same accurate methods and instruments, a definite variation will be found. For example, a cake of 150 denier, 44; filament yarn spun to usual size by the ordinary methods of spinning, will be found to have a denier of 150 on the outside or beginning of the cake and a denier of 154 on the inside. The denier on the thread between the inside and outside of the cake will vary within the above extremes. Likewise the strength on the thread of the inside will be found to be uneven and lower when compared with the thread from the outside or the beginning of the doff. The threads coming from the inside of the cake will dye unevenly and deeper when compared with the dyeing of the threads coming from the outside of the cake. I quote the above figure as an example of one particular case but the variations will depend on the particular conditions under which the cake was spun. However, the figures are relative and approximately true of all cakes spun by any of the usual methods.

I found that these variations can be eliminated if we increase the godet wheel speed as the cake builds up so that the rate of take-off at the end of the doff will be increased to an extent sufficient to give the thread at the end of the dofi" a denier the same and equal to the denier at the beginning of the doff. For example, if a godet wheel operates at a constant speed of 150 R. P. M.,

by any of the usual methods of spinning for a given yarn, it will produce a cake having a denier of 150 on the outside or beginning of the doif and a denier of 154' on the inside of the cake or end of the 4-hour doff. Then it will be necessary for the production of a uniform product throughout 5 the entire thickness of the cake, to increase the speed of the godet wheel so that it will be 150 at the beginning of the doff and 154 at the end of the doff or an increase of 1 R. P. M. of godet wheel speed per hour. Thus by changing the godet 10 wheel speed this invention proposes a method for maintaining uniform characteristics of the thread throughout the entire thickness of a cake by increasing the godet wheel speed as described above.

By the same method the denier and other charl5 acteristics of the thread can be maintained uniform throughout the thickness of the cake by decreasing the amount of viscose delivered to the spinnerette by changing the speed of the pump shaft to a degree required to give the same 20 denier and other characteristics of the thread when comparing the inside and outside of the cake.

The apparatus to be used for producing the change in godet wheel speed or pump shaft speed 25 consists of a variable speed unit connected to the device which controls the speed of the godet wheel or to the metering pump which controls the quantity of cellulosic solution delivered to the spinnerette. 30

By actual tests on deniers, strengths,'and dyeing properties of the thread I found that the change in these characteristics does not take place at a constant rate. Likewise tests made during the spinning operation on the tension of 35 the thread during the entire dofling cycle, show that the variations in tension during the spinning of a full-sized cake do not occur at a uniform rate. These changes occur at a rate approximating the rate at which the thickness of 40 the cake increases during the spinning of the same. The rate of increase in thickness of a cake by the ordinary methods of spinning does not take place at a constant rate, in that the circumference of the cake where the thread is 45 laid down in the cake is continuously changing while at the same time the thread is being fed' to the cake at a constant rate by the usual method of spinning. For example, if we have a cake which is 1% inches thick at the end of a dofl and 50 this cake is spun in a bucket having an inside radius of 3 inches, then the cake at the beginning of the doff has a circumference twice that of the cake on the inside or end of the doif; therefore the rate of increase of the thickness of the in characteristics can be improved if the godet wheel speed is changed at the rate at which the thickness of the cake builds up.

It is therefore another object of this invention to change the godet wheel speed at a rate which is not uniform, but which will be necessary to maintain uniform characteristics of the yarn throughout the entire thickness of the cake by changing the godet wheel speed at any point and for any length of time and to any degree during the spinning of a cake.

It is another object of this invention to provide an apparatus for producing a variable de gree of godet wheel change during the spinning of a cake.

I have shown one embodiment of my invention, together with a modification thereof, in the accompanying drawings, in which:

Fig. 1 is a diagrammatic view, partly in section, of the spinning apparatus;

Fig. 2 is a top plan view of the variable speed unit;

Fig. 3 is a side elevation thereof with the control unit and connected with a godet wheel; and

Fig. 4 is a similar view showing a modification for driving a pump for the cellulosic solution.

Referring to Fig. l, I have shown a spinnerette l arranged to extrude the spinning solution in the form of filaments in a coagulating bath through which the filaments pass to a guide 3, where the filaments are combined in the form of a thread or filament designated T. The thread T passes around a godet wheel 5 of the usual form and the thread may be wrapped entirely around the godet wheel or may extend over several godet wheels, if desired, in the usual way. The thread passes from the delivery side of the godet wheel into a funnel 5 which moves up and down in the usual manner to lead the thread into the bucket.

The spinning bucket is designated generally by the numeral 6 and is designed for collecting the thread and for forming a cake or package of the collected thread. The bucket 6 is rotated by means of an electric motor I, so that as the thread leaves the lower end of the funnel 5, it is thrown out by centrifugal force to form the cake or package in the bucket. When the cake is started, the threads are laid down along the walls of the bucket, as shown in Fig. 1, until the cake of sufficient thickness is built up ready for dofling. The thread T is broken then and the cake, which is designated C, in Fig. 1, is removed from the spinning bucket 6.

This is one of the common methods for spinning artificial silk, but other methods are also common and the invention is not limited to the particular one shown.

It has been found that the cake C is not uniform, as has been pointed out above and the yarn does not have uniform characteristics.

By measuring the tension on the thread on the delivery side of the godet wheel, at the beginning of a. deft or when the bucket is empty, it will be found that it is greater than at the end of the doll or when the cake is of suflicient size suitable for dofling. For example, when spinning a cake of 150 denier, 44 filament yarn by any of the usual methods, the tension on the delivery side of the godet wheel has been tested and found to be 8 grams at the beginning of the doif and 2 grams at the end of the dofi. On the take-up side of the godet wheel, with proper spinning conditions,

the tension on the thread will remain approidmately constant throughout the entire dofi to the end. Thus it. will be seen that the total tension on the thread consisting of the tension on the take-up side of the godet wheel plus the tension on the delivery side of the godet wheel, will vary from beginning to the end of the doif. This variation of tension produces undesirable non-uniform characteristics in the thread at different sections throughout the thickness of the cake.

My present invention makes provision for changing the godet wheel speed slowly and gradually at a constant rate, so that the tension on the thread on the take-up side of the godet wheel can be increased slowly and gradually to compensate for the decrease of the tension on the delivery side of the godet wheel, so that the total tension consisting of the tension on the take-up side plus the tension on the delivery side of the godet wheel can be maintained constant and uniform throughout the thickness of the cake and regardless of the thickness of the cake.

I have shown in Figs. 2 and 3 one form of mechanism that may be used for accomplishing this change in speed of the godet wheel, whereby the speed thereof is varied during the spinning of a cake and as the thickness of the cake increases.

Referring to Fig. 2, a variable speed unit 8 is shown which is of a well-known mechanical construction having a constant speed shaft 9 and a variable speed shaft it. The constant speed shaft 9 is driven from any suitable source of power, such as an electric motor, through a belt or chain ii. The shaft 9 drives the shaft ill by means of a belt 12 which passes around pairs of cone pulleys i 3 and M mounted respectively on the shafts 9 and H] to be shifted toward and from each other alternately by pivoted shifter arms [5 which are connected with the cone pulleys. The speed of the variable speed shaft l0 may be changed in the usual Way by shifting the pulleys 14 further apart or closer together with a corresponding but opposite shifting of the pulleys l3. In other words, the speed of the shaft will depend upon the relative positions of the cone pulleys l3 and II.

For moving the shifter arms IS, the unit 8 has a screw shaft l6, provided with a gear I! on one end thereof which is adapted to be turned by a gear quadrant l8, pivoted at H! on the variable speed unit 8. An arm is connected with the quadrant I8, the end of which arm 20 carries a roller 2! wh ch follows the periphery of a cam 22, against which the roller is held by any well known means such as a spring (not shown). The cam 22 is mounted on a shaft 23 of a speed reduction unit 2| which may be of the usual gear type, having a drive shaft 25 which is connected by a belt or chain 26 witha pulley 27 mounted on the constant speed shaft 9 of the variable speed unit 8.

The variable speed shaft I0 is adapted to be connected with the godet wheel 4 for driving the same and any desired power transmitting mechanism may be used therebetween, such as a belt 28 shown in Fig. 3.

In this way it will be evident that the constant speed shaft 9 will drive the cam 22 at a constant rate, so that the cam may be shaped to turn through a complete revolution during the period of time that it requires for building a complete cake of the desired size in the spinning bucket 6, making it unnecessary to adjust the cam at each dofling interval.

The cam will act on the arm 20 to swing the quadrant l8 and rotate the gear I! gradually during the building of the cake in the spinning bucket in order to accomplish a gradually increasing speed of drive for the variable speed shaft l and consequently for the godet wheel 4. This increase in speed of the godet wheel likewise increases the tension on the take-up side of the godet wheel to compensate for the reduction in tension on the delivery side of the godet wheel, so as to apply uniform tension to the thread or yarn throughout the period of time of building a cake in the spinning bucket. The cam 22 may be designed to give any desired speed for any desired interval of time during the spinning of a cake.

The invention may also be applied to control or compensate for variations in a cake of yarn by changing the quantity of cellulosic solution being delivered to the spinnerette I, as represented in Fig. 4. The variable speed unit 8 in this instance drives a metering pump 30 at a variable speed to control the quantity of cellulosic solution delivered to the spinnerette.

By overcoming the difliculties heretofore encountered in the production of artificial silk thread, or the like such as results from uneven characteristics of denier, strength, stretch, and dyeing properties between the inside and outer parts of the same cake, this invention makes it possible toproduce cakes of much greater thickness than usual and at the same time maintaining uniform characteristics of the thread throughout the entire cake regardless of the thickness of the cake.

Still another method of compensating for an uneven sum tension on the thread is to increase the speed of the godet wheel at a non-uniform rate which will compensate for the now-uniformity in sum tension which will be necessary to maintain uniform characteristics throughout the entire thickness of the cake in that the rate of change of the sum tension takes place approximately at the rate at which the thickness of the cake builds up, which is non-uniform.

I claim:

1. A machine for changing the speed of a revolving shaft including a constant speed shaft, a reduction gear driven by said constant speed shaft, a cam driven by said reduction gear, a quadrant rocked by said cam, an adjusting screw revolved by said quadrant, variable speed mechanism, and means whereby the speed of said mechanism is controlled by the said adjusting screw.

2. In a machinefor driving a shaft at an ununiform rate of speed, a constant speed shaft, a variable speed unit, a reduction gear operated by said constant speed shaft, a cam operated by said reduction gear, and a quadrant rocked by said cam, the said quadrant adapted to turn an adiusting screw to control the said variable speed unit, the said cam being so shaped as to vary the speed of the variable speed unit to provide desirable predetermined rates of speed at predetermined times.

3. In a machine for driving a shaft at an ununiform rate of speed, a constant speed shaft, a reduction gear driven by said constant speed shaft, a cam actuated by said reduction gear, a quadrant rocked by said cam, and an adjusting screw controlling a variable speed mechanism driven by said constant speed shaft, the said cam so shaped as to control the rate of change of the said adjusting screw.

JOSEPH H. BARNES.

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