US3483593A - Drawing apparatus - Google Patents

Description

Dfw-15, 1969 A. M. J. MARLBQROUGH ETAL 3,483,593

DRAWING APPARATUS Filed March 25, 1966 2 Sheets-Sheet 1 Ey 9 MM.

Dec. 16, 1969 A. M, J. MARLBOROUGH ETAL 3,483,593

DRAWING APPARATUS Filed March 25, 1966 '2 Sheets-Sheet 2 9 l 50 32 E: 5r

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/A/I/E/V'UFS United States Patent O US. Cl. 18-1 3 Claims ABSTRACT OF 'IHlE DISCLGSURE In a yarn drawing apparatus of the type including a feed roll, heated plate and a draw roll the yarn is moved to and fro across the face of the plate by a reciprocating guide in order to reduce the formation of ridges of partially decomposed yarn finish components on the plate and to spread the wear over the plate.

This invention relates to the drawing of synthetic thermoplastic filaments and in particular to an improvement in the apparatus used for said drawing wherein the apparatus includes feed and draw rolls and a heated plate.

Drawing, or elongation of synthetic thermoplastic filaments in the solid state, is required to orient the macromolecules comprising the filaments thereby imparting strength to the filaments. Several types of drawing apparatus have been devised for carrying out the elongation step. One commonly used method is to feed the undrawn yarn around a rst roller, usually referred to as the feed roller, then over and in contact with a stationary heated plate to a second roller, usually referred to as the draw roller, rotating at a higher peripheral speed than the first roller. The first roller is usually heated to facilitate elongation of the filaments and sufficient wraps of filamentary yarn are taken around the feed roll such that substantially all the drawing takes place before the yarn leaves the feed roll. The hot plate usually serves to facilitate the completion of any remaining elongation and to heat set the yarn thereby reducing the shrinkage of the drawn yarn, when subsequently subjected to heat treatment, the ratio of the peripheral speed of the draw roller to that of the feed roller is termed the draw ratio.

vWe have now found that the continuous operation of a drawframe of the foregoing type is greatly facilitated and the useful life of the hotplate is increased, by incorporating in the drawframe means for moving the yarn to and fro across the face of the hotplate during the drawing operation.

According to the present invention we provide drawing apparatus for synthetic thermoplastic filamentary yarns comprising a yarn supply, means for feeding the yarn from the yarn supply to a feed roll or rolls, a draw roll or rolls rotating at a higher peripheral speed than said feed roll or rolls and a heated plate intermediate the feed and draw rolls, wherein means is also provided for moving the yarn to and fro across the face of the heated plate.

In drawing synthetic thermoplastic yarn it is customary to coat the yarn with a lubricating and/or antistatic finish before drawing. This finish is usually organic in nature, being composed of vegetable or mineral oils or other organic substances. During drawing of the coated yarn over the heated plate intermediate the feed and draw rolls some of the finish is removed and tends to collect on the heated surface just outside the track of the yarn across the surface, where it is subject to continuous bak- ICC ing which partially decomposes the components 0f the finish forming a hard, abrasive crust or ridge on the surface. If the moving yarn contacts this crust or ridge lilament breakage and also possibly yarn breakage may result leading to poor quality of the drawn yarn or interruption of the drawing process. By means of the present invention formation of the ridges of partially decomposed finish components is substantially reduced, for movement of the yarn across the face of the heated surface has the effect of smoothing out the deposits as fast as they are formed. An important advantage accruing to the use of the present invention is the spreading of the wear on the heated surface more evenly over a larger part of the surface thereby increasing the useful life of the surface. One method which has been suggested to increase the life of the hot plate is to mount the heated plate so that it may be intermittently moved sideways with respect to the yarn exposing a new track for the yarn to take across the plate. However this method is clumsy in use requiring frequent attention by the operator, which is cumbersome in modern drawframes which may incorporate a hundred or more spindles, and does not make full use of the plate surface as each movement must be sufficient to pass the accumulated ridge of finish residue. Another method which has been used but which is mechanically complex and expensive to produce is a rotatable multisurface plate as described in British patent specification No. 960,977. By means of the present invention both spin finish build-up on the plate is substantially reduced and wear is spread evenly over the Whole Working surface of the plate in a simple manner.

Movement of the yarn across the face of the heated plate may be obtained by means of any one of Several types of yarn traverse device, as for example cam and follower to which a yarn guide is attached directly or through a suitable mechanical linkage, or by pneumatic means, by means of which the yarn is caused to reciprocate over a short stroke. The traverse device may be placed before the feed roll or intermediate the feed roll and the heated surface. We prefer to place it before the feed roll in order that only undrawn yarn, which is less subject to damage than drawn yarn, should come in contact with the traverse device.

In some known types of drawing machines for synthetic thermoplastic yarns wherein the means for feeding yarn from the yarn supply to the feed roll or rolls is a pair of cooperating rolls one of which has a rubber or similar high friction resilient surface, a traverse device of constant short stroke is placed before the feeding means. In this case however, due to the pressure at the nip of the c0- operating rolls, which is necessary to ensure uniform supply of yarn to the drawing machine, movement to and fro of the yarn is not transmitted further than the nip 0f these rolls and has no effect upon wear of or build-up of organic residues upon the heated plate. Consequently for satisfactory operation of such drawing machines it is desirable to incorporate an additional traversing means according to this invention.

The kind of reciprocating motion imparted to the yarn `may be simple or complex and we prefer to use a two component motion wherein a primary reciprocation is superimposed upon a slower secondary reciprocation. In this way, `wear of the heated surface over long periods takes the form of a smooth concave track in the surface. This is preferred to the form of Wear obtained with a simple single reciprocation wherein a track having sharper edges (at the extremes of the traverse stroke) is formed.

This in an embodiment of the invention We have placed an hydraulic-pneumatic traverse device before the feed roll, said device causing the yarn to reciprocate at a speed of 3 cycles per minute with a stroke of 0.25 inch (0.625 cm.). Superimposed on this primary reciprocation is a secondary reciprocation of 0.125 inch (0.32 cm.) stroke at a speed of 3 cycles per hour. The extremes of the primary and seecondary strokes are arranged to overlap slightly in order that nish residues should not buildup unduly at the edges of the track and that wear on the plate should be as smooth as possible.

A preferred embodiment of the invention is illustrated in the accompanying drawings wherein;

FIGURE 1 is a diagrammatic representation of one position of a multiposition drawframe.

FIGURE 2 is a diagrammatic representation of an hydraulic-pneumatic means for producing an oscillatory motion and FIGURE 3 is a diagrammatic representation of a linkage translating the oscillatory motion to reciprocating motion of a yarn guide.

Referring to FIGURE 1 the position comprises a yarn feeding means consisting of two cooperating rolls 1 and 2, the upper one 1, having a resilient rubber surface, a yarn guide 3, for moving the yarn to and fro according to the invention, positioned between the yarn feeding means 1, 2 and a heated feed roll 4, whereon drawing of the yarn is to take place. A heated metal plate 5, is situated below the feed roll 4, and before a draw roll 6, which may or may not be heated. Finally a yarn guide 7 and yarn collection means 8 are included to complete the position.

In operation undrawn yarn Y, is fed from the nip between rolls 1 and 2, by `way of the guide 3 to the feed roll 4 around which it is taken a number of times such that drawing is substantially complete when the yarn leaves roll 4 and passes to the hotplate 5 whereon any small amount of drawing is completed and heat setting is effected, the yarn then passing to and around the draw roll 6. The draw roll 6 rotates at a higher peripheral speed than the feed roll 4 and thereby provides the required drawing tension, a suflicient number of turns being taken around the roll 6 such that yarn slippage is substantially prevented. Drawn, set yarn from the draw roll 6 is guided by guide 7 to the collection means 8 which may be a ring-rail type of collector which inserts twist in the collecting yarn.

Referring now to FIGURE 2, apparatus for producing a complex oscillatory motion comprises a compresed air supply control valve 9, Which controls the air supply to a junction 10, whence air is supplied to a double acting valve 11, and to two single acting spring loaded valves 12 and 13. Valves 12 and 13 are attached in spaced apart relationship to a carriage 14 which is slidably engaged inside rail portions 15, of a base plate 16.

A cam 17 is located within a cavity in carriage 14 and is turned in a stepwise manner by means of a needle clutch 18 actuated by a lever arm 19 Which is pivotally attached by rod 20 to arm 21. Arm 21 oscillates about bearing 22 and to one end is ixed a hammer head 23 and to the other end is attached a piston rod 24 connected to pneumatic and hydraulic pistons inside a pneumatichydraulic valve 25. Valve 25 consists of a double acting pneumatic section 26 and a hydraulic section 27. Air is supplied to both sides of a piston in the pneumatic section 26 from the valve 11, and the hydraulic section 27, which also contains a piston on the common shaft 24, is connected through regulating valves 28, 29 and one way valves 30, 31 to a reservoir 32 the internal pressure within which is regulated by means of a spring loaded piston 33.

A shaft (not shown), connected to arm 21 at the bearing 22, transfers the oscillatory motion of arm 21 through the linkage of FIGURE 3 to the yarn guide 3.

In operation the apparatus is set in motion by opening control valve 9 which opening may be effected manually or electrically, as for example, by using a solenoid operated control valve 9. Compresed air is then supplied to juntion and passes through valve 11 to either the left or right hand side of the piston in the pneumatic section 26 of valve 25 pushing it towards the opposite end of its stroke. This movement causes the shaft 24 to be pushed outwards or inwards with a movement which is damped by the passage of oil from section 27 through a regulator valve 28 or 29, through reservoir 32 and back through the second regulator 29 or 28 to the other side of the piston in the hydraulic section 27 of valve 25. Movement of shaft 24 causes arm 21 to move about bearing 22 so that head 23 contacts valve 12 or 13 momentarily opening it. Opening of valve 12 or 13 causes a pulse of compressed air supplied to the valve from junction 10, to enter valve 11 and the piston therein to be displaced from one end to the other, this displacement in turn causing the air supplied from junction 10 to be passed to the opposite side of the piston in section 26 of valve 25 from that to which it was initially supplied thus reversing the cycle of events.

The primary oscillation of the shaft attached to arm 21 at bearing 22 is thus obtained by the movement of head 23 to and fro between successive contacts with valves 12 and 13. However the overall motion of this shaft is complex for as arm 21 moves in one direction (either to left or right) the needle clutch 18 actuated through rod 20 and lever 19, causes a small increment of rotation of cam 17 and a small sliding movement of carriage 14. This movement of carriage 14 alters the position of valves 12 and 13 with respect to the bearing 22 and hence the point at which the head 23 contacts said valves. This has the effect of combining with the primary oscillation a secondary movement, of very much longer period. Movement of arm 21 in the opposite direction does not cause the needle clutch to move cam 17 as the action of the clutch is unidirectional.

The period of oscillation maybe adjusted by means of the regulators 28 and 29 and piston 33 acts as a buffer for oil lpulses.

Referring now to FIGURE 3 as hereinbefore described an oscillatory motion is imparted to arm 21 about the bearing 22. This motion is given to la shaft 34 supported from the frame of the drawing machine by a bracket. 35, to which shaft a cam, 36, is non-rotatably attached. Depending from the ybracket 35 is an arm 37 pivotally attached thereto, to the free end of which a bar 38 is xed in substantially parallel relationship to shaft 34. T o bar 38, the yarn guide 3, and a cam follower 39 are fixed so as to move therewith. The follower 39 is attached to bar 38 opposite to cam 36 and cooperates therewith, cams 36 and follower 39 being urged together contact by means of a spring 40 attached at one end to the bracket 35 and at the other to the arm 37.

Any synthetic thermoplastic yarn which may be oriented and strengthened by drawing may be drawn using drawing `apparatus according to this invention. Thus a process for drawing synthetic thermoplastic lamentary yarns comprises feeding the yarn from a supply thereof to a feed roll or rolls, which roll or rolls may be heated or unheated, then over and in contact with a stationary hot plate of suicient length to provide the required contact time, to a `draw roll or rolls rotated at a higher peripheral speed than said feed roll or rolls to a yarn collecting means, characterised in that the yarn, is caused to reciprocate with a simple or complex motion of the foregoing type across the hot plate.

What we claim is:

1. In drawing apparatus for synthetic thermoplastic lamentary yarns of the type including a yarn supply, means for feeding y-arn from said supply, a feed roll, a draw roll rotating at a higher peripheral speed than said feed roll and a heated plate intermediate the feed and draw rolls over which the yarn passes longitudinally of -itself during operation, the improvement which comprises means for reducing the formation on said heated plate of ridges of partially decomposed yarn finish components, said means including a yarn guide and reciproeating drive means for imparting to said yarn guide a two component action comprising a primary reciprocation superimposed upon a slower secondary reciprocation in a manner such that the extremes of primary and secondary reciprocation overlap slightly.

2. Drawing apparatus according to claim 1 wherein the means for moving the yarn to and fro is operable at a point intermediate the yarn feeding means and the feed roll.

3. Drawing apparatus according to claim 1 wherein the means for moving the yarn to and fr0 is operable at a point intermediate the feed roll and heated plate.

References Cited UNITED STATES PATENTS 2,199,411 5/1940 Lewis 28-62 X 2,272,666 2/1942 Hoifman 264--167 2,278,888 4/1942 Lewis 264-167 X 2,289,232 7/1942 Babcock 264-290 X 2,920,345 1/1960 Dyer 264-167 X 2,975,474 3/1961 Smith 264-167 X 3,302,385 2/1967 Ruddell et al. 57-157 FOREIGN PATENTS Great Britain. Great Britain. Japan.

Japan. France. Japan.

IULIUS FROME, Primary Examiner I. H. WOO, Assistant Examiner U.S. C1. X.R.

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