US3218675A - Apparatus for crimping fibers - Google Patents

Description

Nov. 23, 1965 w. H. HENDRIX 3,218,675

APPARATUS FOR CRIMPING FIBERS Filed June 27, 1965 24 2a if; 2

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INVENTOR WALTER H. HENomx BY N/QQMA/ ATTORNEY United States Patent Office 3,218,675 Patented Nov.` 23, 1965 3,218,675 APPARATUS FOR CRIMPING FIBERS Walter H. Hendrix, Lugoff, S.C., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed June 27, 1963, Ser. No. 291,069 3 Claims. (Cl. 19-66) This invention relates to apparatus for mechanically crimping synthetic filamentary tow.

The need for crimp in commercial textile processing of fibers into staple yarns is well established. Since most synthetic filaments have little or no tendency to crimp as produced, it is necessary to impart crimp mechanically in the manufacturing process, using, for example, the stufling-box crimper such as described tin U.S. Patents 2,311,174 and 2,747,233, or some variant thereof.

It has long been recognized in the art that mechanical crimping leads to degradation of phyical properties of synthetic filaments. Properties such as fiber tenacity and elongation, both of which are important to textile processability and to broadest utility of fabrics made therefrom, are adversely affected by crimping. Furthermore, the tendency of most synthetic fibers to lose mechanically-induced -crimp which is imparted without benefit of heat setting, imposes severe demands on initial crimp intensity to compensate for this loss. The development of crimp of initially high intensity in commercial rate processes, has required that the crimping process be operated in a critical performance area wherein minor process variations can lead to severe product property degradation. The criticality of this operation is further exaggerated by demand for increased speed of production.

It has now been found that non-uniformity in distribution of filaments as the tow enters the bite of the crimper stuffing rolls is a major cause for mechanical degradation of filaments when crimping under critical conditions of high speed and high crimp intensity. In extreme cases, near-fushion of filaments into agglomerations which are not readily opened by normal textile processing, as well as gross filament rupture, may occur. Such damaged tow -is unsuitable for commercial textile use.

It is the primary object of this invention to provide apparatus for uniformly crimping filamentary tow. It is a more specific object of this invention to provide improved apparatus which can be operated at high speeds to crimp tow with a minimum of mechanical damage to the filaments. Other objects ill become apparent from the detailed description which follows.

The objects of this invention are achieved by providing in tow crimping apparatus which includes cooperating rolls which form a nip for advancing a tow and a crimping chamber below the rolls for receiving and restricting the advance of the tow, a pair of stationary flanged spool guides adjacent to and in advance of the rolls. The guides have their major axes parallel to the nip formed by the rolls and are aligned in staggered relationship along the axial path of advance of the tow to contact opposite surfaces of the tow and deflect it from its normal axial path as it passes between the guides to the rolls. Surprisingly, by dellecting the tow from about 5 to 22 from its normal course of travel as it passes between the spool guides, the filaments in the tow become oriented in a uniform pattern as they enter the bite of the feed rolls with the crimped filaments issuing from the stufling-box showing little, if any, damage.

For a detailed description of the invention in its preferred form, reference is made to the accompanying drawings wherein? FIGURE 1 is a diagrammatic sketch of the apparatus;

FIGURE 2 is a d-iagrammatic vertical sectional view of the apparatus taken along line 2-2 of FIGURE 1, and FIGURES 3 and 4 are fragmentary sectional views of the flange and adjoining barrel portions of embodiments of the spool guides shown in FIGURE l.

With reference to FIGURE l, two feed rolls 12 and 14 having smooth cylindrical peripheral surfaces are mounted in opposed relationship to engage and forcibly feed a flamentary tow 16 into crimping chamber 1S. Mounted immediately above rolls 12 and 14 are flanged spool guides 20 and 22 with the inner surfaces of their respective flanges 24, 24 and 26, 26 substantially aligned with the vertical sides of rolls 12 and l14. Spool guides 20 and 22 are fixedly positioned in a staggered relationship with respect to the normal course of travel of tow 16 and are mounted on arms 28 and 30 of frame 32.

In operation tow 16 is passed from a source not shown between the flanges 24, 24 and 26, 26 and in contact with the peripheral surfaces of spool guides 20 and 22 when the lateral edges of the tow are aligned and the path of travel is slightly changed. -As the tow cornes into contact with the surfaces of the spool guides 20 and 22, the deflection and Contact with the surfaces causes the individual filament to become aligned in a uniform pattern. The tow is then engaged by feed rolls 12 and 14 and forced into crimping chamber 18. As illustrated in FIGURES l and 2 of the drawing, the tow is confined in the crimping chamber by shoe plates 11 and 13 and by front and back plates 15 and 17. The front and back plates 15 and 17 have their inner surfaces in adjacent parallel relationship with the peripheral surfaces of rolls 12 and 14 for restricting the lateral passage of the tow between the rolls. Pressure may be applied through openings 19 and 21 to inserts 23 and 25 to prevent lateral emergence of Ifilaments from the nip of the rolls. Crimping of the filaments is accomplished by the action of a clapper plate positioned near the base of the crimping chamber, not shown, which restricts the rate at which the filaments are permitted to pass through chamber 18.

The configuration of the flanged spool guides may be varied to achieve various effects. While a smooth barrel 34, shown in FIGURE 3, provides greater freedom for filament distribution between flanges 24, 24' and 26, 26', a grooved barrel 36, as shown in FIGURE 4, may be used to force cross-flow of filaments from heavy areas in the tow to the thinner areas. In a preferred embodiment, the barrel portion has a corrugated configuration with the grooves -being spaced from about 0.1 to 0.12 inch apart and being from about 0.025 to 0.035 inch deep. The tapered entrance to the surface of the barrel which is provided by the flanges accomplishes a foldover of the thin edges which are always present in a running tow. The tow is preferably adjusted to a total width slightly greater than the distance between the flanges by use of conventional spreading or contracting parabolic guides at a point upstream from the flanged spool guides.

The benefit of the flanged spool guides to crimping uniformity and thereby to product quality is substantial. Uniformity of crimp and of tow quality heretofore unobtainable is regularly obtained with the apparatus of this invention. As shown previously, a major factor in satisfactory processability of a multi-filament tow is intimate interlacing of adjacent filaments so as to permit handling of the entire bundle as a consolidated ribbon. Without interlacing at all points along its length, the tow may split which prevents the filament interaction necessary to broadening, narrowing, and uniformizing filament distribution in the tow structure by means of, for example, convex or concave parabolic guides.

A test procedure for evaluating splitting which has been devised takes into consideration not only the frequency of splits but also their length. A split which is from barely apparent to yards in length is graded as a 2 point split. One which has a length of 6 to 11 yards is assigned a value of 4 points. Those which are 12 yards -or longer are assigned a value of 6` points. With this rating in mind, the comparisons of the test described below can more readily be understood. All ratings are based on 100 lbs. of tow.

A test wherein this invention was compared with a previous process which employed finger guides to control only the lateral position of the tow at each edge thereof demonstrated striking improvement in a critical tow quality characteristic. In this test, several hundred pounds of 3 denier per filament tow, having a total denier of 470,000, made by each process were run on a Turbo Stapler which is commonly used in the textile trade to break tow to staple. The quality of the entering tow and the emerging sliver were monitored visually throughout the test. Tow made using the apparatus of this invention had 5.6 degradation points for splits while the tow made by use of the finger guides showed 102 points. A split occurs due to failure of the crimping process to interlace the filaments properly. It is not possible to maintain a uniform distribution of feed to the Turbo Stapler in the area of a split, and a sliver defect known as a slub may develop. A slub results from exactly parallel breaks in a group of filaments and generally occurs in a thick area -of the tow cross section. Since each filament in a slub is presented simultaneously to drafting rolls in succeeding steps of textile processing, they will not be drafted properly and will lead to a defect in the final yarn. In this test, less than half as many slubs were observed in the product made using the apparatus of this invention as were observed in the product made using the linger guides.y

In another test, the inliuence of the lianged spool guide on maximum speed of crimper operation without tow defects was determined. With the finger guides for control of the edges of the tow as it enters the bite of the stufing rolls, a maximum of 300 yards per minute processing without easily observable degradation in the crimped tow was found. With the apparatus and process of this invention, extended runs at 360 yards per minute were made without tow degradation, and short tests have shown speeds as high as 400 yards per minute to be feasible.

Since various embodiments of this invention will become apparent to those skilled in the art, the invention is not to be limited by the specific embodiment disclosed herein except as set forth in the appended claims.

I claim:

1. In tow -crimping apparatus which includes cooperating rolls which form a nip for advancing a tow, a crimping chamber below said rolls for receiving and restricting the advance of said tow, and a pair of opposed plate members having the inner surfaces in adjacent parallel relationship with the peripheral surfaces of said rolls for restricting the lateral passage of said tow between said rolls: a pair of stationary flanged spool guides adjacent to and in advance of said rolls, said spool guides having their major axes parallel to the nip formed by said rolls, the fianges of said guides having inwardly tapering surfaces with the bases of said flanges being in a plane essentially parallel to and in alignment with the lateral surfaces of said rolls, said guides being arranged in staggered relationship with the axial path of advance of said tow to contact opposite surfaces of said tow and defiect it from its normal axial path as it passes between said guides to said rolls.

2. The apparatus of claim 1 wherein said flanges have inwardly tapering surfaces at their extremities and essentially straight portions adjacent the base of said ange.

3. The apparatus of claim 2 wherein the surface between the `flanges of said guides has a corrugated configuration consisting of annular grooves and ridges.

References Cited by the Examiner UNITED STATES PATENTS 1,893,809 1/1933 Stone et al 28-72 1,966,507 7/1934 Langstreth 242-42 2,311,174 2/1943 Hitt 19-66 2,419,320 4/ 1947 Lohrke 28-72 2,811,770 11/1957 Young et al 28-72 X 3,145,429 8/1964 Resor 19-157 FOREIGN PATENTS 816,778 7/ 1959 Great Britain.

DONALD W. PARKER, Primary Examiner.

Claims (1)

1. IN TOW CRIMPING APPARATUS WHICH INCLUDES COOPERATING ROLLS WHICH FORM A NIP FOR ADVANCING A TOW, A CRIMPING CHAMBER BELOW SAID ROLLS FOR RECEIVING AND RESTRICTING THE ADVANCE OF SAID TOW, AND A PAIR OF OPPOSED PLATE MEMBERS HAVING THE INNER SURFACES IN ADJACENT PARALLEL RELATIONSHIP WITH THE PERIPHERAL SURFACES OF SAID ROLLS FOR RESTRICTING THE LATERAL PASSAGE OF SAID TOW BETWEEN SAID ROLLS: A PAIR OF STATIONARY FLANGED SPOOL GUIDES ADJACENT TO AND IN ADVANCE OF SAID ROLLS, SAID SPOOL GUIDES HAVING THEIR MAJOR AXES PARALLEL TO THE NIP FORMED BY SAID ROLLS, THE FLANGES OF SAID GUIDES HAVING INWARDLY TAPERING SURFACES WITH THE BASES OFF SAID FLANGES BEING IN A PLANE ESSENTIALLY PARALLEL TO AND IN ALIGNMENT WITH THE LATERAL SURFACES OF SAID ROLLS, SAID GUIDES BEING ARRANGED IN STAGGERED RELATIONSHIP WITH THE AXIAL PATH OF ADVANCE OF SAID TOW TO CONTACT OPPOSITE SURFACES OF SAID TOW AND DEFLECT IT FROM ITS NORMAL AXIAL PATH AS IT PASSES BETWEEN SAID GUIDES TO SAID ROLLS.

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