US2676495A - Electronic denier control - Google Patents

Description

April 27, 1954 J. s. SENEY ELECTRONIC DENIER CONTROL 5' Sheets-Sheet 1 Filed June '7, 1950 INVENTOR.

JOHN s. SENEY ATTORNEY p 27, 1954 J. s. SENEY 2,676,495

ELECTRONIC DENIER CONTROL Filed June 7, 1950 5 Sheets-Sheet 2 WESYON METER INVENTOR. JOHN- 5. SENEY A TTORNEY April 27; 1954 J. 5. SENEY ,4

ELECTRONIC DENIER CONTROL Filed June '7, 195Gv 5 Sheets-Sheet'3 INVENTOR.

JOHN S. SENEY A TTORNEY April 27, 1954 .-.l. s.- SENEY ELECTRONIC DENIER CONTROL 5 Sheets-Sheet 4 Filed June 7, 1950 EIDEIUD INVENTOR JOHN S. SENEY ATTORNEY April 27, 1954 J. s. SENEY ELECTRONIC DENIER CONTROL 5 Sheets-Sheet 5 Filed June 7, 1950 INVENTOR.

JOHN S. SENEY m7 ATTORNEY Patented Apr. 27 1954 ELECTRONIC DENIER CONTROL John S. Seney, Henrico County, Va., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Application June 7, 1950, Serial No. 166,750

This invention relates to an improved speed control for spinning machines, such as viscose rayon spinnin machines, to produce finished yarn of more uniform denier. More particularly, this invention is concerned with the spinning of viscose rayon on a bobbin spinning machine and with an electronic control of the machine drive shafts to efiect improved results.

In the manufacture of regenerated cellulose yarn by the viscose process, provisions are made for varying the rate of draw-off and/or pump de-" livery to produce in its finished form a yarn of more uniform denier and dyeab-ility than could be provided in the absence of these corrective changes. In the bobbin spinning process as the yarn cake builds up and the peripheral lay of the yarn becomes greater and greater, the rotational speed of the bobbin must be diminished. Because of variations in shrinkage that arise throughout the bobbin package this diminution in rotational speed should be other than a straight line compensation and numerous me chanical arrangements have been proposed and used with varying degrees of success.

The mechanical compensators used are dem pendent on constant speed drive motors and generally the pump shaft speed is assumed to be at a constant R. P. M. and the pump delivery therefore constant, whereas there are sometimes variations of as much as 5% in the spinning solution delivery and not infrequently denier variation in the finished yarn may be as much as 7% above or below the stated denier or an overall variation as much as 14%.

' It is, therefore, an object of this invention to provide more accurate control of the driving elements to maintain the denier more nearly constant and to provide means for compensatively altering the rate of yarn draw-off should variations in pump delivery arise. Other objects will be apparent from the description that follows.

/ The objects of this invention are accomplished by synchronizing the bobbin speed and pump speed plus the desired speed variable included on the cam through the use of an electronic circuit in which changes in bobbin speed are made to effect proportional changes in pump speeds, or vice versa. Briefly, this invention is accomplished by having in a balanced or balanceable relationship two tachometer generators or one tachometer generator and a constant voltage source of direct current electricity e. g. a battery. Where two tachometer generators are used one is directly connected to the bobbin drive shaft and one is directly connected to the pump shaft 5 Claims. (Cl. 74-395) and so wired and controlled through a cam operated variable resistance that the desired proportional speeds of these two shafts are maintained. The electrical connections and details of construction and operation are shown in drawings listed below and explained hereinafter. While the invention is described with particular reference to viscose spinning, the apparatus can be applied to the spinning or extrusion of any synthetic yarn.

In the drawings:

Figure 1 is a flow sheet showing the control apparatus of this invention in simplified form;

Figure 2 is a detailed electrical wire diagram of'the control apparatus shown in Figure 1;

1 Figure 3 is a side elevation of the cam operated variable speed controller;

Figure 4 is a plan view of the apparatus shown in Figure 3 and Figure 5 is taken on line 55 of Figure 3.

Referring to Figure 1, G-I is a tachometer generator attached to th bobbin shaft drive (connection not shown) and G4 is a tachometer generator attached to the shaft driving the viscose pump or pumps (connection not shown). These generators are connected so that the negative connection H1 is common to each. The voltage output of each generator is proportional to the speed of the shaft to which each is connected and in'the electrical circuit shown no current fiows when the output of the generators is the same.

Connected in parallel with generator (3-! are resistance potentiometers R-2 and R-B. A highly accurate indicator for tachometer G-l is provided as follows:

As shown in Figure 1, a bias voltage is obtained from REC-l, a selenium rectifier, and this D. C. voltage is applied across R-9. The negative connection of REC-l is connected to the common negative terminal ill of G-l. The slider All of R-9 can then be set to produce the necessary exact biasing voltage to the tachometer indicator M-l. A resistor R-3 is connected across the output of (3-! so that any ratio of the voltage developed by G-l can be obtained between the slider 50 of R-3 and the common negative terminal 10 of G-I. Connected between slider 50 of R-3 and the tachometer indicator M-l is a variable series resistor R4. This provides a fine adjustment to the tachometer indicator. To illustrate, assume G-l is turning R. P. M. and slider 50 at R-3 is set midway of R-3 and slider 40 at R-9 is so adjusted that M-l reads 0 R. P. M. If G-l is speeded up to 200 R. P. M., it will show full scale of the tachometer indicator meter provided R4 has been properly set for this particular meter movement and the meter M-I will show only speeds above 140 R. P. M. and no more than 200 R. P. M. Meter M-l has a scale which will be magnified in increments of 1 R. P. M. between the speeds of 140 to 200 B. P. M.

The output of 6-! is connected across potentlometer R-2 and that of G-2 is connected across the resistor R-5. Resistor R-2 is the high speed control voltage divider and it applies the desired voltage from G-I to input transformer T4. Resistors R- and R8 are connected in series and shunt the slider contact Ill of R-G to the common negative junction 18 of G-l and G-2. The resistors R-5, R-6 and R-B control the voltage output from G-2 to transformer T-A, Transformer T4 has dual input and between it and the electrical bridge comprising R-5, R-6 and R4 is a converter CON-| which is a single pole double throw switch operating in synchronism with the line voltage furnished by T-l 8-! through connections X--Y (see Figure 2). This switch is polarized by a permanent magnet, so that one of the contacts will always be closed during the negative half cycle of the supply voltage from 8-,! T1 and the other contact will be closed during the positive half cycle. Any flow of current .due to a difference in potential between slider contact 20 of R-2 and 35 of 3-8 is converted from direct current to ,a proportional .60 cycle alternating current by the converter CON-l and transformer T- d.

Transformer T-4 a ts as a phase shifting and coupling device between the bridge circuit and the electronic vol age amplifier 80. 'lhe phase of the output voltage at 6 depends on the polarity of the voltage from sliders 20 and 35 at R-2 and R43, respectively. After conversion, the A. C. Voltage Output is amplified by a conventional electronic amplifier hook-up 80 (shown in detail in Figure 2). The motor MOT-3 is a two phase control motor. It is a brushless, reversible, variable speed induction motor of the drag cup type. MOT-3 is connected, as described below, to the control screw 91 or the bobbin drive P. I. V. (se Figure 4). P. I. V. is the generally accepted designation for a positive-drive, infinitely variable sp ed changer, one type being disclosed in U. S. Patent No. 2,076,202 at page 2, column 1, line 60. Depending upon the amount of voltage and the polarity of the current, MOT-3 changes the speed of the bobbins and since tachometer generator C i is attached to it, it changes also thespeed of G-l. and the amount of its output.

In order to control denier or mass per unit length of the yarn spun, the amount of viscose or other spinning solution must be taken into account. As stated, tachometer generator G-Z is attached directly to the metering pump shaft (not shown) of the spinning machine and fur,- nishes voltage to one side of the network. The slider contact 3!] at R 8 is operated by cam 35. The movement of cam 35 is controlled by synchronous motor MOT-l, which drives this cam on the electronic circuit or, when this is off, mechanically operates the P. I. V. control screw. The compensating voltagev coming from R-8 is then changed as required. From this, it can be seen that the ratio of yarn windup to pump delivery will at all times stay constant, provided the cam is made for straight line compensation.

vThe electronic circuitcan'be seen in more; detail by reference to Figure 2 and to the iiollo wfns d si n. W t ge erators Gel nd.

4 connected as shown and turning at a given speed and with slider contact 2c of R-2 set at a certain point, a voltage, for example, 1 volt, is obtained between the negative common connection 10 and the slider contact 29 of R4. The slider contact I!) of R-fi is set to obtain a positive potential of 1 volt between it and the common negative connection it. If slider contact 30 of R 8 is set at the extreme upper position as shown in Figure 1, the 1 volt potential is also obtained at the contact 36. With a 1 volt potential at contact 20 and at contact 30, no current would flow between these points. If the speed of a generator, say G-i, changes for example, from 1 volt to 2 volts, there would exist a difference in potential and current would flow between contacts 20 and 30.

This current is converted to 60 cycle A. C. by CON! and transformer T-4. Ihe A. C. voltage output is amplified by a conventional electronic amplifier hook-up through tubes V-I, V-2 and power amplifier V-3. ,The amplifier is supplied direct current from rectifier tube V4 and 5-2 T-l The amplified current is supplied to MOT-3 by power amplifier tube V-3. The other motor winding is continuously energized by line voltage from 8- 1 T4. The phase of the current coming from V-3 determines the direction of rotation of MOT-3 and its amplitude determines the Speed of the motor.

With 6-2 turning at a constant rate to produce 1 volt between in and 30 and G-j now pro: ducing 2 volts, the slider 20 at R-2 becomes of a positive polarity and the slider 31] of a negative polarity. In view of the negative voltage, MOT-3 will rotate in a direction to slow down the bobbin because it is driving the control screw of the bobbin P. I. V. Since G-I. is attached to the bobbin drive, MOT-3 will operate in the slow down direction until the voltage difference between the sliders at 20 and 30 is elimi: nated. At this point the entire network is in balance.

If G-! produced a smaller voltage than G-2, say 0.5 volt, a difference of 0.5 volt would exist between sliders 20 and 30 of the opposite polarity. Slider 30 at R-8 would be plus and slider 20. at 3-2 would be negative in polarity. MOT-3 would run in a reverse direction raising the speed of the bobbins and, hence, G-l until zero voltage difierence again was attained. Thus, if the speeds of G-l and G4 are not the same, MOT-3 will bring about the change needed to keep the network in balance.

With this in mind R5 is sov adjusted that a voltagedrop is eifected across R-8 equal to the desired speed change of G-l or the bobbin wind.- up speed. Assuming that G-I, develops ,2 volts at 200 R. P. M. and 1.5 volts at R. P. M., 3-5 is so adjusted that 0.5 volt is the drop across R-B. The voltage at slider lil of R-G will be set to produce 2 volts between it and the common negative connection. With the above stated conditions the voltage between the sliders 20 at R-2 and 3d at 11-8 will be 0. provided that G.- -l is turning 200 R. P. M. Now if slider 3c is movedv from its top position (Figure 1) so that it is at the other end of R43, there will be a voltage. d'iiierehce of 0.5 volt. In order for there to be- 0. volt between sliders 2e and 30, G-l will have to turn at l50 R. P. M. Since MOT-3 keeps the: voltage'between sliders 3D and Ill at Q. then by changing the position along resistance R- 8.-of ts. s id r he obb n s ed ca be cha ed from 20,0 R. P. M. to 150713.33. At the start of the. spin-,cycle beforev the bobbins begin to build up yarn, G- -2 will be generating 2 volts. If for some reason it does not rotate sufficiently to do this, but say 1.99 volts, MOT-3 reduces the speed of G-I or the bobbins so that G-I produces only 1.99 volts.

The movement of contact an to vary the resistance of R-B involves a mechanical unit containing certain electrical switches which relate the movement of contact to thechange needed to keep the network in balance over the desired speed pattern. This unit is shown in Figures 3, 4 and 5.

The entire unit is mounted on a frame 41. Shaft 4 is a drive shaft connected to the bobbin drive P. I. V. by sprockets and chain 5. A plate or support member 2 is mounted so that it can pivot about shaft 4. This plate 2 has attached to it gears I'I, I8, 38, I3, 39 and cycle cam 35, cam follower 36, and slider 30 in contact (not shown, see Figure I) with R-8. The unit 88 bolted toplate 2. supports cam follower 36, rack 42, gear 45 and one end of spring 86.

.Mounted on the stationaryframe. 41 is shaft 63..which is connected to and driven by MOT-3, the electronic control motor. 63 is gear I6 which drives gear I8 when the latter is in the position shown. Gear I8 in turn drives gear. I1. Since gear I I-is. attached to shaft 4 which in turn is attached to the bobbin P. I. V. control screw, shaft 63 driven by MOT-3 controls the bobbin P. I. V. drive or the speed at which the bobbins are driven.

Also mounted on frame 41 is shaft 64 which is driven by cycle timer motor MOT-I. This drives gear I2 which in. turn drives gear i3 (mounted on pivotable. plate 2) when gear I3 is in the position shown in Figure 5. Gear I3 drives gear 38 through gear 39 and gear 38 drives cycle cam in a clockwise direction. As this cam rotates it moves cam follower 36, which bears roller 31 resting on the periphery of cam 35, in an outwardly direction. Cam follower 33 has on one side a rack, designated as 42 in Figure 5. This rack turns gear which is attached to slider contact 30 and the resistance at R-8 is changed accordingly. Thus, MOT-4 drives cam 35 which through cam follower 36 changes the compensating voltage coming from R-8.

At the start of anew spinning cycle the operator turns reset switch actuator 54 to the reset position and holds it there until the machine is set to high starting speed. MOT-2 starts up driving shaft 62 and since plate 2 is connected to it by shifter link 93, plate 2 is made to pivot around shaft 4. As plate 2 moves switch actuator 34 eventually causes microswitch B to open and this stops MOT-2 and keeps it stopped as long as the operator holds the reset switch actuator 54 in the reset position. The pivoting of plate 2 to this reset position has caused gear It to go out of mesh with gear I6 and gear I2 to go out of mesh with gear I3. The speed reset hand wheel 55 attached to shaft 4 is free to turn and the operator turns it to set the bobbin speed at the start of the spinning cycle or 2 0 R. P. M. Cam reset spring 23 also causes cam 35 to return to the start position; cam stop 28 comes back to rest on the stop or shock absorber 29 (see Figure 4). Slider 30 of R-8 is returned by spring 86 to its start position. Now the machine has been reset and the operator allows reset switch actuator 54 to assume its normal position. This by-passes switch B and MOT-2 starts up again; the bearing 2 pivots so that the gears mesh momentarily and then go out of Attached to shaft 6. mesh and it continues to pivot until microswitch A is opened. This stops MOT-2. Gears I6 and I8 now mesh as do gears I2 and I3. MOT-3 is now driving the control screw to the P. I. V. and the timing motor MOT-I is advancing the cycle cam 35 through its compensating cycle.

vIn addition to the foregoing, provision may be made to reduce the bobbin speed automatically by a straight line speed reduction by MOT-I in the event of failure of the electronic system. This is done automatically by having connected, as shown in Figure 2, between the sliders 30 at Rr-8 and 2!! at R-2 a sensitive, normally-open relay (JR-4 which is connected and set to close if more than 2 micro amperes flow between the sliders of R8 and R-2 (indicating that the electronic system is failing because current in this circuit should always be near zero if the system is in balance).

Assuming that the electronic control is'failing and CR-4 has closed its control contacts, circuit is made from the line voltage neutral through the closed contact of CR4 to trip out warning light L-5 and to coil of (JR-2 through normally closed contacts of reset switch G to the other side of the line. v This, of course, energizes (JR-2 opening contacts-Band 5 of (IR-2 and closes 5 and 4. This reverses timer motor MOT-I. Contacts I and 2 of CR-2 open and 2 and 3 close. This applies line voltage through normally closed reset switch G through contacts 2 and 3 of (JR-2 through normally closed switch C to reset motor MOT-2 to the other side of the line. Reset motor MOT-2 starts up and shifts plate 2 so that gears I2 and IS engage thus connecting the P. I. V. control screw with timer motor MOT I whereby MOT-I reduces the bobbin speed at a constant rate. Limit switch C is opened by pin 94 thereby st0p' ping MOT-2 with gears I2 and I8 in mesh. CR-3 is provided to energize CR2 when the electronic control unit is removed from service for repair; The switch C is a normally closed switch and is operated .by pin 94 which is keyed to MOT2 and is fixed to open switch 0 when gears I8 and I2 are in mesh or when (MOT-I is in control of the drive. A jumper is installed in plugs P-I2A and PI2-I2 which keep CR-3 energized as long as these plugs ar in place. The removal of either will de-energize (JR-3 thereby energizing CR-2, placing the compensator on straight line compensation. Thus, if the electronic control fails for some reason, the rotational speed of the bob-- bins will be diminished in accordance with the: cake build-up. 3 I

Upon. the resettingof CRf-4, CR-Z drops out again reversing MOT-4 energizing MOT-2 through reset limit A. Plate 2 then opens reset limit A when gears I6 and I8, and I2 and I3 are again in mesh. .When the reset switch is operated, current flows to reset motor MOT-2 from normally closed contacts of reset switch F (see Figures 2 and 3) through doff limit switch B thus running MOT2 until B contact is opened by actuator 34 attached to plate 2. In this position gears are neutralized for the reset and upon the release of reset switch to MOT2, witch G again closes and starts MOT-2 so that the proper gearing is again engaged at gears I6 and I8 and at gears I2 and I3. If relay CR-Z is energized the P. I. V. will be operated from the timer motor MOT-I. If CR-Z is dropped out, the P. I. V. will be driven from the electronic control motor MOT-3.

In order to prevent CR-4 closing while the machine is being reset a relay CR-I is energized by caveats the voltage applied to the dotting ri'oil ='motor. KThi *motor must be running "during the :dofii'ng operation but-it is= turned off as soon -as the ma chine is reset and restrung.) The normally closed contacts opened by "CR-I "disconnect the relay CR4 from the system thus preventing its accidental action during the reset operation. In order to prevent the P. I. V. control screw rrom being turned past its -limits, limits'witches E aJnd Dareeonn'ected in series with the supply voltage to MOT-'3 1 and MOT- i In some instances, as for "example, in bucke't spinning or even "bobbin processes, a constant voltage supply such as a battery may housed in place of G 2. Itis, of' course reoogiiized that the draw-off device-maybe a windu'psuch as a zbobb'hi or :it may be simply "a roller-such as a lgodet.

By 1 means of this invention excellent uniform ity in yarn denier is obtained. The Variation in denieris-n'o more than it of 1 percent or ch 1 200- denier yarn i3 denier, which makes the yarn admirably-suited for any purpose. In the case of fine denier yarn,s'uchas 100 denier, the'normal variation resulting from this control is scarcely measurable being of theorder of A denier.

While the invention has been described in terms of denier controL'it may, of course, "be used in connectionwith any sort of desired compensation. Fox-instance, to improve dyeing 'um'i'ormity throughout "the spin package or to produce :ya'rn having greater uniformity in any one prop'erty or abetter average uniformity of a numiber o'f prop erties, such as-elon'gation, tenacity or other physicall rproperties that may be affected advantageously by altering the proportional "rate of spinning solution delivery and yarn draw-off.

The invention is applicableto any type of spinhing machine such as bucket or yarn advancing reel collections-or other continuous yarn'production methods as well as the bobbin collection method. It may be used to advantage not only with regenerated cellulose yarn produced by the viscose process but also any coagulating bath spinning process or to dry spun or melt s un yarns of any'description. For exampleycuprammonium cellulose yarn, cellulose ester yarns, cellulose ether yarns, polyvinyl yarns, such as polyvinyl chloride, polyvinyl acetate, 'polyactrylonitrue, nylon, polyester yarn, etc..

Any departure from the procedure described herein which conforms to the principles of the invention is intended to be included within the scope of the claimsbelow.

I claim:

1. Apparatus for controlling the'speed of one driven shaft relative to the speed "of a "second independently driven shaft which "comprises a pair of tachometer generators connected in series opposition and arranged to be driven respectively at speeds proportional to the speed "of said' first shaft'and the speed of said second shaft, are sistance network connected to receive the uni- 8 directional output of said-generators, an amplifi'er circuit including converter "means "respon- "'si-v'e to amplitude and direction of flow of current insaid resistance network for providing an alternating current output signal of proportional magnitude andof a phase related "to the polarity ofsaid output, and speedcontrol'me'ans responsive to the output signal of said amplifier and adapted to vary'the relative speeds of said shafts in accordance with said magnitude and phase until said outputs'ign'al is nu'llified'as the result of corresponding changes in the speeds 'of said generators.

2. Apparatus as defined in claim -1 in which said speed control means includes a reversible, variable speed induction motor connected to a control screw of a positive-infinitely-variable drive connected to one of saidshafts.

Apparatus as defined claim 1 in which a resistor in said resistance network is continuousi-y adjusted by a cam driven by a cycle time motor, thereby varying said output signal and causing the relative speeds of said shafts to change as afunctio'n of time in'a predetermined manner.

4. in apparatus for controlling the speed of one=drlven shaft relative to 'thespeed of a 'second independently driven shaft by the action of a motor adapted to change the speed'ratio of said shafts .in response to an error signal derived through an electrical control circuit from tachometer generatorsconnected in series opposition and arranged to bedriven atspeeds proportional to the respective shaft speeds, the improvement comprising relay means responsive to an excessive value of said-"error signal indicative of abnormal functioning of said=control circuit and operative to disconnect saidmotorand to replace it by means'for reducing the speed of said first shaitgradually until :it stops to prevent uncontrolled driving of said first shaft.

5. The apparatus improvement defined in claim 4 in which said first shaft is driven through a positive-infinitely-variable drive having a control screw and the means for reducing the speed of "said shaft comprises a timer motor connected to said screw to rotate it so as to reduce the speed'of said shaft at a constant rate.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1 1,926,275 FitZGEIald v Sept. 12, 1933 2,076,202 Lewellen Et 'al Apt. 6, 1537 2,314,332 "Kline- Sept. 10, 1940 2,237,985 Garman Apr. 8, 1941 2,306,157 Edwards at al Dec. 22, 1942 2,325,331 Edwards et al July 27, 1943 2,437,972 'schmitz Mar. 16, 1948 2,454,731 Burkholder Nov. 23, 1948 2,583,074 Aubert 'et a1. Jan. 22, 1952

Images