US3377853A

US3377853A - Twist tester

Info

Publication number: US3377853A
Application number: US553367A
Authority: US
Inventors: Harry J Carter
Original assignee: FMC Corp
Current assignee: FMC Corp
Priority date: 1966-05-27
Filing date: 1966-05-27
Publication date: 1968-04-16
Anticipated expiration: 1985-04-16

Description

H. J. CARTER TWIST TESTER April 16 2 Sheets-Sheet 1 Filed May 2'7. 1966 m m v w E mm 5% 3 mm ON mm H. J. CARTER TWIST TESTER 2 Sheets-Sheet 2 Filed May 27. 1966 mmoom United States Patent 3,377,853 TWIST TESTER Harry J. Carter, Wilmington, DeL, assignor to FMC Corporation, Philadelphia, Pa., a corporation of Delaware Filed May 27, 1966, Ser. No. 553,367 6 Claims. (Cl. 73-160) The present invention relates to an apparatus for ascertainin g the number of turns per inch or other unit of length in a twisted strand, particularly a strand of yarn, and more especially to an apparatus for determining without the intervention of a human operator the amount of twist at spaced distances along the length of a strand whereby the average amount of twist along the length of the strand may be accurately ascertained.

The amount of twist affects the strength, coefficient of friction, dye absorption, and other characteristics of a yarn, as well as the hand or feel of the fabric made of the yarn. It is therefore important for the throwster or yarn manufacturer to know exactly how much twist is being inserted and for the fabricator to know the amount of twist in the yarn being used for weaving or knitting the fabric. Since the amount of twist inserted into a yarn depends upon the speed of the twisting device and the speed with which the yarn is passed through the twisting device, it is theoretically possible to know the amount of twist, but in practice one or both speeds may vary from the intended speed. It is therefore desirable to be able to ascertain accurately the actual amount of twist in a given strand or a strand from a particular production run.

Prior to the present invention, the amount of twist in a yarn was ascertained by cutting a specimen length of yarn and clamping it at points a known distance apart.

One of the clamps was then rotated to take the twist out of the yarn while the other clamp was urged to move away from the rotated clamp as the yarn elongated due to the removal of twist. This twisting was continued until the yarn was twisted in the opposite direction sufficiently to restore the other clamp to its original position. A counter was provided for indicating the number of revolutions of the rotated clamp and by dividing the total number of revolutions by a factor of two (half of the revolutions being effective to untwist the specimen and the other half re inserting the twist but in the opposite direction) and then dividing by the number of inches between the clamps, the number of turns of twist per inch of length was ascertained. An apparatus similar to those normally used for this operation is described in US. Patent No. 1,928,271. In use, this prior art apparatus is slow and tedious in that it requires the constant attention of an operator and the indicated results are also dependent at least to some degree upon the operator.

It is an object of the present invention to provide a yarn twist tester which, once the yarn has been threaded therethrough, will indicate the amount of twist without further attention by a human operator.

It is a further object of the invention to provide a yarn twist tester capable of performing a test at spaced points along a continuous length of yarn whereby the average twist along the yarn may be ascertained.

A further object of the invention is to provide an appar-atus which may be used for testing for the amount of twist at spaced points along a yarn strand and wherein the twist in the yarn is the same after testing as before.

Other and further objects, features, and advantages of the invention will become apparent as the description of a preferred embodiment thereof proceeds.

Referring now to the drawings:

FIG. 1 is a diagrammatic side elevational view of the apparatus;

Cal

"ice

FIG. 2 is an enlarged fragmentary sectional View of one of the yarn clamps; and

FIG. 3 is a wiring diagram.

The apparatus comprises a pendulum 10 secured to a shaft 12 pivotally mounted between a pair of uprights 14, only one of which is shown in FIG. 1. An arm 16 is secured to shaft 12 and carried on its free end are selective weights 18 by means of which the pendulum is urged to swing in a counterclockwise direction. For convenience in lacing the apparatus, a suitable stop 20 secured to the end of an arm 22 adjustably connected to one of the uprights 14 may be provided for limiting the counterclockwise movement of the pendulum. Conveniently, the pendulum may take the form of a tube having a plug 24 in the lower end thereof and another plug 26 located above the lower end of the tube. A slot 28 is provided in the tube just below plug 26 and slidably mounted within the tube is a yarn-gripping member 30, which is urged by a spring 32 to engage plug 26 so as to grip the yarn as will presently be explained. Secured to yarn-gripping member and extending through an opening in plug 24 is a rod 34 having an enlarged lower end 36. A downward pull on rod 34 disengages member 30 from plug 26 so that a yarn strand may be laced through the slot 28.

A rotatably mounted element 38 is provided with a pair of yarn-gripping

jaws

40 and 42 carried by and urged together by

spring members

41 and 43. Carried at the end of a hollow shaft 44 is a tapered jaw-operating member 46. Shaft 44 is slidable longitudinally within element 38, but is keyed thereto so as to rotate therewith. Secured to or formed as a part of element 38 is a pulley 48 by means of which said element may be rotated. The hollow shaft extends entirely through element 38 and the pulley 48 and on its outer end is provided with a collar 50 between which and a shoulder of pulley 48 is a spring 52 bymeans of which shaft 44 is urged toward the left, as viewed in FIG. 1 to position tapered jaw-operating member 46 so that the spring-pressed

jaws

40 and 42 may close upon and grip a yarn strand extending therebetween. A shaft 54 rotatable about a vertical axis is mounted in the vicinity of collar 50 and an arm 56 is secured to the upper end of said shaft and has a free end located closely adjacent collar 50 and secured to the lower end of shaft 54 is an arm 58 connected by a link 60 to the armature of a pull-type solenoid 62. The rotatable shaft 54 and the parts connected thereto are shown diagrammatically in both FIGS. 1 and 3.

The yarn to be tested is indicated at 64 and in initially lacing up the apparatus the yarn is manually drawn from a supply, not shown, and threaded first through a suitable guide 66. The operator then manually releases the gripping member 30 by pulling down on rod 34 and threads the yarn through the slot 28 of the pendulum. An ample supply of yarn is pulled through slot 28 and the operator then releases the rod 34 so that the yarn is gripped to the pendulum. The operator then presses on collar 50 to open

jaws

40 and 42 and threads the yarn between the jaws and through the hollow shaft 44 and between a set of rubber-covered

feed rolls

68 and 70. When the operator releases collar 50, the yarn is gripped to the rotatablymounted element 38 through the spring-pressed

jaws

40 and 42.

Feed roll 68 is secured directly to the shaft of an electric motor 72 or may be connected to the motor through a speed reduction unit. Roll is freely rotatable upon a shaft 74 carried by an arm 76 which is pivotally mounted at 78 on a fixed support. A spring 80 extending between one end of arm 76 and a fixed anchor normally holds roll 70 out of engagement with roll 68. Connected through a spring 82 to the end of arm 76 opposite from the spring p 80 is the armature of a pull-type solenoid 84 and when said solenoid is energized, as will presently be explained, roll 70 is moved toward roll 68 so as to pinch the yarn therebetween, whereby when motor 72 is activated, the yarn will be drawn through the apparatus. A counter 86 is connected to shaft 74 so as to indicate the number of times that roll 70 is raised.

Before detailing the means for accomplishing the same, the manner of operation in performing a test will be briefly explained, it being assumed that the yarn is laced through the apparatus. The means gripping the yarn to the pendulum and the means gripping the yarn to the rotatable element 38 are both released; that is, they are released from engagement with the yarn. Solenoid 84 is energized so that the yarn is gripped between

feed rolls

68 and 70 and motor 72 is staited to cause the yarn to be pulled through the apparatus. After a predetermined length of yarn has been pulled through, motor 72 is stopped but solenoid 84 remains energized so that the yarn is gripped between the feed rolls. The yarn is then gripped to the pendulum which at that time has been swung by the weights 18 to the position shown in FIG. 1. Located between

feed rolls

68 and 70 and the rotatable element 38 is an arm 88, one end of which is operatively connected to a clock motor 90. Arm 88 is normally held down by a spring 92 but immediately after the yarn becomes gripped to the pendulum, clock motor is started and this swings the free end of arm 88 in an upward path which brings the arm into engagement with the yarn so as to tension the yarn between the feed rolls and the pendulum. This tension causes the pendulum to swing in a clockwise direction and when the yarn-gripping portion of the pendulum reaches a predetermined position (referred to hereafter as a home position), clock motor 90 is stopped and

solenoids

62 and 84 are deenergized. This causes the yarn to become gripped to the rotatable element 38 and released from the feed rolls. The element 38 is then caused to rotate in a direction which first untwists the yarn so that the pendulum 10 may swing away from its home position as the yarn elongates due to the removal of the twist, and the rotation of element 38 is continued until an equal amount of twist is inserted into the yarn in the opposite direction so as to restore the pendulum to its home position. When the pendulum is restored to its home position, it causes activation of means which reverses the rotation of element 38 and the yarn is again untwisted and retwisted until the pendulum again moves away from and is restored to its home position. Due to the double untwisting and retwisting, the yarn now has its original twist, and this second time that the pendulum is restored to its home position it causes the whole cycle described above to be repeated.

Rotatable element 38 is provided with a shoulder 94 which operates a switch 96, which in turn causes one to be added to a counter 98 for each revolution of element 38. Over a period of time the counter 86 indicates the number of tests performed, since this counter is operated every time the feed roll 70 is raised against feed roll 68 to cause the yarn to be drawn through the apparatus. The average twist per inch of yarn is computed by dividing the total number of revolutions of element 38 asindicated by counter 98 by a factor of two (since there are two twisting operations per test) and then dividing by the number of tests as indicated by counter 86 and by the distance between the

jaws

40 and 42 of element 38 and the

gripping elements

26 and 30 of the pendulum when the pendulum is in its home position. Conveniently, the last-mentioned distance may be ten inches.

After the initial lacing-up, the periodic release of the yarn from the grip of the pendulum is accomplished by a solenoid 100 which, when energized, pushes down on a lever 102 which is-pivotally mounted at 104 and is provided with a bifurcated end which overlies the enlarged lower end 36 of rod 34. A spring 106 normally holds lever 102 out of engagement with the end 36 of rod 34 and with the lever free of engagement with the end of 34, rod 36 is free to swing within the bifurcated end of the lever.

Rotatable element 38 is driven by a reversible electric motor 188 (see FIG. 3) through a belt 110 engaged with the pulley 48 and with a pulley 112 on the shaft of the motor.

Referring now to FIG. 3, the testing operation is begun by closing a switch 114 in a line 116 so as to energize a polarized light source 118 connected to an alternating current power line 126* and 122 through the line 116 and a line 124. Light source 118 is directed toward a light sensitive cell 126 and when light strikes the cell a circuit is established to the coil of a relay R through line 128 from the power line 120, line 130 from the cell to the relay coil and line 132 from the relay coil to power line 122. Light source 118 and cell 126 are mounted on opposite sides of pendulum 10 above the pendulum supporting shaft 12. The pendulum extends above shaft 12 and carries on this upper extension a shield 134 (see FIG. 1) having therethrough a small opening 136. Light from source 118 is permitted to strike the sensitive part of cell 126 only by passing through the opening 136 and said opening is aligned with the cell only when the pendulum is in its home position.

After closing switch 114, the operator closes a switch 135 in a line 136 to establish a circuit to a clock motor 148 through the line 136 from power line 120 and a line 142 to the power line 122. From this point on, no further attention by the operator is required until the counter 86 indicates that the desired number of tests have been run. If desired, the aparatus may very easily be arranged to automatically stop after a preselected number of tests, but mechanism for doing this has not been shown.

Motor drives a shaft 144 which carries a series of cams arranged to operate a series of switches A, B, C, D, E, and F and shortly after the shaft starts to turn, switches D and F are closed. One side of switch F is connected to power line 128 and the other side is connected through a lead 146 to solenoid 106 which in turn is connected through a lead 148 to the power line 122.. Thus closing switch F energizes solenoid 180 which disengages the pendulum 18 from the yarn as previously explained. One side of switch D is connected to power line 120 and the other side is connected through a line 150 to a contact bar 152 of a normally closed relay R Through the contact bar 152, line 150 is connected to a line 154 which leads to solenoid '62 which in turn is connected to power line 122 through a line 156. Thus closing, switch D energizes solenoid 62 to cause the yarn to be released from the grip of rotatable element 38 as aforesaid.

As the cam shaft 144 continues to rotate, switches C and E are closed. One side of switch C is connected to power line 120 and the other side of said switch is connected through a line 158 to solenoid 84 which in turn is connected through a line 160 to power line 122. Thus closing, switch C energizes solenoid 84 to cause feed roll 70 to pinch the yarn strand between it and feed roll 68 as aforesaid. One side of switch E is connected to power line 120 and the other side of this switch is connected to motor 72 through a lead 162 and the motor is connected through a lead 164 to power line 122. Thus closing of switch E is effective to start motor 72 whereby the yarn strand is drawn through the pendulum gripper and through the rotatable element 38 until a fresh portion of yarn extends between the pendulum and element 38. At this time the cam shaft 144 has rotated to a position to open switch E, whereupon motor 72 stops and no further yarn is drawn through.

Right after switch E is opened, switch F is permitted to open to break the circuit to solenoid 100, whereupon the yarn becomes gripped to the pendulum as previously explained. Immediately after switch F opens, a cam on shaft 144 closes switch A, one side of which is connected to power line 120 and the other side of which is connected by a line line 166 to a second switch bar 168 of the normally closed relay R The other end of bar 168 is in contact with a line 170 leading to clock motor 90 which is connected to the power line 122 through a lead 172. Thus a circuit is established to motor 90 and said motor starts to run to cause tensioning of the yarn strand whereupon pendulum is swung in a clockwise direction until it reaches its home position wherein light from the source 118 is permitted to strike the light sensitive cell 126 as previously explained.

Activation of light sensitive cell 126 closes the circuit to the coil of normally open relay R as aforesaid to close the contacts of said relay. One of the relay contacts is connected to power line 120 through a lead 174 and the other contact is connected to the coil of a stepping switch 176 through a lead 178. The coil of switch 176 is also connected to power line 122 through a lead 180 and thus closing relay R is effective to activate the stepping switch. The stepping switch has a common lead 182 connected to power line 122 and a stepping contact engageable with any one of three

contacts

184, 186, 188. Upon this first described closing of relay R the stepping contact of switch 176 moves out of engagement with contact 184 with which it is normally engaged and into engagement with contact 186 to establish a circuit to the coil of relay R through a line 190 leading from the contact 186 to the relay coil and a line 192 leading from the relay coil to the power line 120. Energization of the coil of relay R opens both sets of contacts of this normally closed relay and this simultaneously deenergizes solenoid 62 to cause the yarn strand to become gripped to the rotatable element 38 and stops clock motor 90, both as previously explained.

As cam shaft 144 continues its rotation a cam thereon becomes effective to permit switch C to open thus breaking the circuit to solenoid 84 and freeing the yarn from the grip of feed rolls 68 and 70. A slight further rotation of cam shaft 144 closes switch B, one side of which is connected to power line 120 and the other side of which is connected through a lead 194 to one of the contacts of a normally closed relay R The other contact of relay R is connected through a lead 196 and a full-wave bridge rectifier 197 to one of the two input contacts of a manually operated double pole double throw reversing switch 198 the other input contact of which is connected to power line 122 through rectifier 197 and a line 200. The two output contacts of switch 198 are'connected to the input contacts of a solenoid operated reversing switch 202 the output contacts of which are connected to the reversible motor 108.

At this time it will be mentioned that yarn is sometimes twisted in one direction known as S twist and sometimes in the opposite direction known as Z twist. Since in performing a test the first operation is to remove the twist, the operator must examine the yarn to ascertain the direction of the twist. Having determined this, the manually operated reversing switch 198 is conditioned so that the current passing through this switch and through switch 202 when the latter is in its normal attitude is effective to drive the motor 108 in the direction to remove the twist from the yarn. Thus, with switch 198 properly conditioned before or right after the yarn is laced through the apparatus, closing of switch B is effective to start motor 108 to run in the direction to remove twist from the yarn.

As the twist is removed from the yarn, pendulum 10 swings away from its home position whereby light sensitive cell 126 and relay R are deenergized. When all of the original twist is removed from the yarn, rotatable element 38 continues to be rotated by motor 108 in the same direction whereby reverse twist is inserted into the yarn. When the amount of reverse twist becomes the same as the amount of original twist, pendulum 10 will have been returned to its home position to again cause activation of relay R whereupon the stepping contact of stepping switch 176 is moved out of engagement with contact 186 and into engagement with contact 188.

Engagement of the stepping contact of switch 176 with the contact 188 establishes a circuit to the coil of a solenoid 204 which controls reversing switch 202. The circuit is established through a line 206 leading from contact 188 to the solenoid coil and a line 208 leading from the coil to power line 120. When the solenoid 204 is thus energized it reverses switch 202 which in turn reverses the rotation of motor 108 and rotatable element 38. R0- tatable element 38 then removes the reverse twist from the yarn and continues to rotate until the original twist is restored to the yarn. During this rotation of element 38, pendulum 10 swings away from its home position and returns to the home position. Upon this return of the pendulum, relay R activates stepping switch 176 to swing the stepping contact thereof out of contact with contact 188 and into contact with the contact 184, thus breaking the circuit to solenoid 204 whereupon reversing switch 202 becomes conditioned as it was originally and at the same time establishing a circuit to the normally closed relay R through a line 210 leading from contact 184 to the relay coil and a line 212 leading from the relay coil to power line 122. When relay R is activated it breaks the circuit to line 196 leading to the switch 198 and thereby stops motor 108. The total number of revolutions of element 38 during this test is recorded on counter 98. As the cam shaft 144 continues to turn the above-described cycle is repeated and these cycles continue until the operator opens switch after observing from counter 86 that the desired number of tests have been run or after an automatic control shuts the apparatus oif.

Having thus described a preferred embodiment of the invention, what is claimed is:

1. Yarn twist testing apparatus comprising a rotatably mounted yarn gripping element adapted to have a yarn strand extended therethrough, resilient means for closing said gripping element so as to grip the yarn strand, a first releasing means for opening said gripping element so that the yarn strand may be pulled therethrough, yarn gripping means having a home position located at a preselected distance from said yarn gripping element, resilient means for closing said gripping means so as to grip a yarn strand, a second releasing means for opening said gripping means so that the yarn strand may be pulled therethrough, means urging said yarn gripping means in a direction away from said yarn gripping element, drive means for rotating said rotatably mounted yarn gripping element about an axis coincident with the axis of the yarn, and yarn take-up means for pulling the yarn strand through the gripping element and the gripping means when they have been released from the yarn by said first and second releasing means.

2. The apapratus set forth in claim 1 comprising means for activating said first and second releasing means whereby the rotatable yarn gripping element and the yarn gripping means are released from the yarn strand, and means operable upon said activation of said first and second releasing means for activating said yarn take-up means to pull the yarn strand through said rotatable yarn gripping element and said yarn gripping means.

3. The apparatus set forth in claim 2 comprising means for deactivating said second releasing means whereby said yarn gripping means becomes gripped to the yarn strand, and tensioning means for tensioning the yarn strand to draw said yarn gripping means to its home position against the action of the means urging said yarn gripping means in a direction away from said yarn gripping element, said tensioning means drawing the yarn strand through said yarn gripping element during the tensioning.

4. The apparatus set forth in claim 3 comprising means activated when said gripping means reache said home position to deactivate said first releasing means and start said drive means whereby said rotatable yarn gripping element is gripped to the yarn strand and rotated in the direction to remove the twist from the yarn strand.

5. The apparatus set forth in claim 1 comprising sequentially operated, (1) means for activating said first and second releasing means whereby the rotatable yarn gripping element and the yarn gripping means are released from the yarn, (2) means for operating said yarn take-up means to draw the yarn through the yarn gripping element and the yarn gripping means, (3) means for deactivating said second releasing means whereby said gripping means grips the yarn strand, (4) means for tensioning the yarn strand to draw the yarn gripping means to said home position, (5) means for deactivating said first releasing means whereby said gripping element grips, the yarn strand, and (6) means for rotating said rotatably mounted yarn gripping element to remove the twist from 8 the yarn strand and insert an equal amount of opposite twist into the strand.

6. The apparatus set forth in claim 5 comprising means for recording the number of rotations of said rotatably mounted yarn gripping element and means for recording the number of operations of said yarn take-up means.

References Cited UNITED STATES PATENTS 1,928,271 9/1933 Smith 73-158 2,037,274 4/1936 Scott 73-158 2,590,398 3/1952 Geganschatz 7395.5

LOUIS R. PRINCE, Primary Examiner. J. NOLTON, Assistant Examiner.

Claims

1. YARN TWIST TESTING APPARATUS COMPRISING A ROTATABLY MOUNTED YARN GRIPPING ELEMENT ADAPTED TO HAVE A YARN STRAND EXTENDED THERETHROUGH, RESILIENT MEANS FOR CLOSING SAID GRIPPING ELEMENT SO AS TO GRIP THE YARN STRAND, A FIRST RELEASING MEANS FOR OPENING SAID GRIPPING ELEMENT SO THAT THE YARN STRAND MAY BE PULLED THERETHROUGH, YARN GRIPPING MEANS HAVING A HOME POSITION LOCATED AT A PRESELECTED DISTANCE FROM SAID YARN GRIPPING ELEMENT, RESILIENT MEANS FOR CLOSING SAID GRIPPING MEANS SO AS TO GRIP A YARN STRAND, A SECOND RELEASING MEANS FOR OPENING SAID GRIPPING MEANS SO THAT THE YARN STRAND MAY BE PULLED THERETHROUGH, MEANS URGING SAID YARN GRIPPING MEANS IN