US3422860A - Unidirectional braking means for terry loom pile warp let-off mechanism - Google Patents

Description

Jan. 21, 1969 J. T. SHORT I 3 ,8 0 UNIDIRECTIONAL BRAKING MEANS FOR TERRY LOOM FILE WARP LET -OFF MECHANI SM Filed July 18. 1967 Sheet of 5 FIG] INVENTOR JOE T. SHORT A ORNEYS.

Jan. 21 1969 J. T. SHORT 3,422,360

UNIDIRECTIONAL KING MEANS FOR TERRY LOOM FILE WA LET-OFF MECHANISM Filed July 18, 1967 Sheet 2 of 5 INVENTOR JOE T. SHORT BZZZW46M A ORNEYS,

iled July 18, 1967 shei of 5 Jan. 21, 1969 J, T. SHORT 22,86P UNIDIRECTIO BRAK MEANS FOR TERRY LOQM ARP L; -OFF MECHANISM FIG. 3 I08 FIG. 4

INYENTQR JOE T. $HORT.

QRNEYS United States Patent 3,422,860 UNIDIRECTIONAL BRAKING MEANS FOR TERRY LOOM PILE WARP LET-OFF MECHANISM Joe T. Short, West Point, Ga, assignor to Callaway Mills Company, La Grange, Ga., a corporation of Georgia Filed July '18, 1967, Ser. No. 654,206 US. Cl. 139-25 13 Claims Int. Cl. D03d 39/22; F16d 63/00 ABSTRACT OF THE DISCLOSURE In a loom for weaving terry cloth having pile loops formed on the face thereof, including, a weaving means, a pile warp beam for holding a supply of pile yarns, a pair of interconnected pile warp let-off rolls for drawing the pile yarns from the pile warp beam and feeding the yarns to the weaving means, and drive means operatively connected to the let-off rolls for intermittently rotating the rolls so that prescribed lengths of the pile yarns will be drawn intermittently from the pile warp beam and fed to the weaving means for forming the pile loops; the improvement comprising a unidirectional brakin means associated with the let-off rolls for permitting the rolls to be rotated in the direction for drawing the pile yarns from the pile warp beam and preventing the rolls from being rotated in the opposite direction so that the lengths of the pile yarns intermittently drawn from the pile warp beam by the let-off rolls will be uniformly of the prescribed length and the pile loops formed in the terry cloth will be of a uniform height.

BACKGROUND OF THE INVENTION Field of the invention This invention is directed to an improvement in looms for weaving terry cloth, and relates to a means for insuring that the lengths of the pile warp yarns intermittently drawn from the pile warp beam and fed to the weaving means of such a loom are of a uniform length so that the pile loops formed on the face of the terry cloth woven by the loom will be of a uniform height. More specifically, the invention concerns a unidirectional braking means associated with the pile warp let-off mechanism of a terry loom which permits the let-off mechanism to operate only in the direction for drawing the pile yarns from the pile warp beam of the loom while terry cloth is being woven thereby.

Description of the prior art In convention terry looms, the warp yarns are fed to the weaving means of the loom from a pile warp beam and a ground warp beam. The pile warp beam supplies the pile warp yarns which are used for forming the pile loops on the face of the fabric and the ground warp beam supplies the ground warp yarns which are used for forming the base of the fabric.

Formation of the pile loops requires that prescribed lengths of the pile yarns be fed intermittently to the weaving means of the loom. The prescribed lengths of the pile yarns are drawn intermittently from the pile warp beam and fed to the weaving means by a let-off mechanism. Generally, the let-off mechanism comprises a pair of interconnected let-off rolls to which is operatively connected a ratchet gear and pawl driving means for intermittently rotating the rolls. The pile yarns are fed around and between the rolls so that when the rolls are rotated the pile yarns will be drawn from the pile warp beam and fed to the weaving means.

Frequently, while the pawl of the driving means is indexing to a new position on the ratchet gear, the letoff rolls will rotate backward in the direction opposite to the direction for drawing the pile yarns from the pile warp beam. This backward rotation of the rolls is effected by a torsion force which is exerted on the rolls by the pile yarns, resulting from the tension force exerted on the yarns by the pile warp beam; the latter, and therefore the former, force varying as an indeterminate function of the amount of yarn on the pile warp beam. When backward rotation of the rolls occurs, the lengths of the pile yarns fed to the weaving means will be less than the prescribed length required for forming pile loops of the desired height, resulting in a row of short loops. The short loops impair the appearance of the terry cloth and therefore significantly decrease the value thereof.

In order to minimize the problem of short pile loops, conventional terry looms usually include a friction braking device operatively connected to the pile warp let-off rolls to apply a braking force in both directions of rotation. If properly adjusted, this bi-directional friction brake permits the rolls to be rotated forward intermittently by the relatively heavy force of the driving means for drawing the pile yarn from the pile warp beam, but prevents the rolls from rotating backward in the opposite direction under the light pulling force of the yarns. However, since the amount of pile yarns on the pile warp beam changes continuously, such devices, to be effective, must be attended constantly and adjusted frequently by a skilled operator. Thus, frequently, due to inattention or improper adjustment of the braking device, backward rotation of the let-off rolls occurs, resulting in a row of short pile loops. Consequently, the problem of short pile loops has not been solved by such devices.

SUMMARY OF THE INVENTION The present invention obviates the problem resulting in the formation of short pile loops by providing a unidirectional braking means associated with the let-off rolls of a terry loom which prevents the rolls from rotating backward in the direction opposite to the direction for drawing the pile yarns from the pile warp beam while terry cloth is being woven by the loom. The unidirectional braking means thus insures that the prescribed lengths of the pile yarns required for the formation of pile loops of a desired height will be fed to the weaving means of the loom. Further, the braking means of the invention operates essentially automatically and does not require the constant attention of a skilled operator.

The unidirectional braking means basically comprises a stationary hub connected to the loom frame, a rotary hub connected to the shaft of one of the let-off rolls, and a locking means interposed between the hubs which locks the rotary hub to the stationary hub whenever a force is exerted on the let-off rolls tending to rotate the rotary hub and let-off rolls in the direction opposite to the direction for drawing the pile yarns from the pile warp beam.

In addition, the unidirectional braking means includes an override means for releasing the locking means so that when desired for maintenance or other purposes, the rotary hub and let-off rolls may be rotated backward in the direction opposite to the direction for drawing the pile yarns from the pile warp beam.

With the foregoing in mind, it is an object of the present invention to provide an improvement for terry looms which insures that the pile loops formed on the face of the terry cloth woven by the loom will be of a uniform height.

It is a further object of the invention to provide a unidirectional braking means associated with the let-off mechanism of a terry loom which insures that the lengths of the pile yarns fed to the weaving means of the loom for forming pile loops on the face of the terry cloth woven by the loom will be of a uniform length.

It is an additional object of the invention to provide a unidirectional braking means associated with the pile warp let-off rolls of a terry loom which prevents the rolls from rotating backward in the direction opposite to the direction for drawing the pile yarns from the pile warp beam of the loom while terry cloth is being woven thereby.

It is also an object of the invention to provide a unidirectional braking means associated with the pile warp let-oft" rolls of a terry loom which includes an override means for permitting the let-off rolls to be rotated backward in the direction opposite to the direction for drawing the pile yarns from the pile warp beam of the loom when desired.

With the foregoing summary of the invention in mind, a description of the preferred embodiment thereof is given below in connection with the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective rear view of a terry loom showing the pile warp let-off mechanism of the loom and the unidirectional braking means of the invention;

FIG. 2 is a schematic sectional view of a terry loom;

FIG. 3 is a sectional view of the unidirectional braking means of the invention; and

FIG. 4 is a sectional view taken on line 44 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT A terry loom is shown in FIGS. 1 and 2 having a structural frame 12. Journalled in frame 12 are a pile warp beam 14 for holding a supply of pile warp yarns 16 and a ground warp beam 18 for holding a supply of ground warp yarns 20.

Warp yarns 16 and 20 are fed to a weaving means 22 comprising a loom harness 24 and a reed 26. Harness 24 and reed 26 weave terry cloth fabric 28, forming pile loops on the face thereof. As fabric 28 is woven by weaving means 22, it is accumulated on a storage roll 32.

Formation of pile loops 30 requires that prescribed lengths of pile warp yarns 16 be fed intermittently to weaving means 22. The prescribed lengths of the pile yarns are drawn intermittently from pile warp beam 14 by a let-off mechanism 34.

Pile warp let-off mechanism 34 comprises a pair of pile warp let- off rolls 36 and 38 which are secured to shafts 40 and 42, respectively; the shafts being journalled for rotation in frame 12. The let-off rolls are interconnected by gears 41 and 43, affixed to the respective roll peripheries, so that the rolls will rotate together.

As shown in FIGS. 1 and 2, pile yarns 16 are passed around and between let-off rolls 36 and 38 which frictionally engage and hold the yarns so that when the rolls are rotated forward in the direction indicated by arrows 44 the yarns will be drawn from pile warp beam 14 and fed to weaving means 22 in the direction indicated by arrows 45.

A driving means 46 is provided for intermittently rotating let-off rolls 36 and 38 forward so that pile yarns 16 will be fed intermittently to weaving means 22. Driving means 46 includes a ratchet gear 48 atfixed t shaft 42 and a cooperating driving pawl 50 which is pivotally carried by an extension 51 of an actuating arm 52. One end of arm 52 is journalled on shaft 42; the other end of the arm being attached to a push rod 53 by an adjustable pivotal connection 55. Push rod 53 is reciprocated intermittently by the loom driving means (not shown) causing arm 52 to oscillate about shaft 42, and pawl 50 to intermittently index with the teeth of gear 48 and rotate the gear in the direction of arrows 44. As gear 48 is rotated during the power stroke of the pawl, shaft 42 4 and interconnected let-off rolls 36 with.

A friction braking device 54 also is associated with the let-off rolls, comprising a drum 56 secured to shaft 42 and an adjustable friction clamp 58. The braking force exerted on drum 56 in both directions by clamp 58 is regulated by an adjustment unit 60 comprising a bolt and spring-biased wing nut. When properly adjusted, device 54 will prevent let-off rolls 36 and 38 from being rotated backward by the relatively light tension force exerted on the rolls by pile yarns 16 during the indexing stroke of pawl 50, but will permit the rolls to be rotated forward by the relatively heavy driving force exerted on gear 48 during the power stroke of the pawl. To insure this result, device 54 must be attended constantly and adjusted frequently by a skilled operator because the tension force exerted on the pile yarns, and therefore the torsion force exerted on the let-off rolls, vary continuously as the amount of yarn on pile warp beam 14 changes. Frequently, however, device 54 is left unattended for a short period of time or is improperly adjusted and backward rotation of the let-off rolls results during the indexing stroke of pawl 50. When this occurs, the lengths of the pile yarns fed to weaving means 22 will be less than the prescribed length required for forming pile loops of the desired height and a row of short loops will be formed.

To overcome the deficiencies of device 54, a unidirectional braking means 62 is operatively connected to letotf rolls 36 and 38 for insuring that the rolls will not rotate backward while terry cloth is being woven by weaving means 22. As shown in FIG. 3, braking means 62 includes a central shaft 64 which is afiixed to and constitutes an extension of shaft 42. A rotary hub 66 is secured to shaft 64 by a set screw 68 which also passes through shaft 64 for securing the latter shaft to shaft 42. Disposed about shaft 64 is a bearing 74 and a stationary hub 70; hub 70 being connected to frame 12 by a torque arm 72. A section 76 of rotary hub 66 and a section 78 of stationary hub 70 concentrically overlap each other, with section 76 being disposed about section 78.

Locking means are interposed between overlapping sections 76 and 78 to lock rotary hub 66 to stationary hub 70 whenever a force is exerted on let-off rolls 36 and 38 by pile yarns 16 tending to rotate the rotary hub and let-off rolls backward during the indexing stroke of pawl 50. The locking means comprises a plurality of bearings 80 which are carried in recesses 82 (FIG. 4) formed in overlapping section 76 of rotary hub 66. Each of recesses 82 opens toward overlapping section 78; and is defined by a pair of side walls 84 and 86, and a linear camming surface 88. As shown in FIG. 4, the side walls are curved inwardly at their outer ends to form a smooth transition between each of the Walls and the camming surface.

Each camming surface 88 faces overlapping section 78, and extends between a first end 90 and a second end 92. First ends 90 are oriented toward the forward direction of rotation of rotary hub 66 and second ends 92 are oriented toward the opposite or backward direction of rotation of the rotary hub. As each camming surface extends from first end 90 to second end 92, the surface slopes away from overlapping section 78 so that the distance between first end 90 and section 78 is less than the distance between second end 92 and section 78.

Each of the bearings 80 has a substantially circularshaped cross-section and conveniently may have a cylindrical-shaped external configuration. The cross-sectional diameter of bearings '80 is greater than the distance between first ends 90 and section 78, and less than the distance between second ends 92 and section 78. Thus, when the bearings are positioned in proximity to second ends 92, they will be carried freely in recesses 82 and will have no effect on the rotation of rotary hub 66 with respect and 38 rotate thereto stationary hub 70. However, when the bearings are positioned in proximity to first ends 90, they will become wedged in recesses 82, between camming surfaces 88 and overlapping section 78, and lock rotary hub 66 to stationary hub 70. When this occurs, rotary hub 66, shaft 64, shaft 42 and let-off rolls 3'6 and 38 will be locked in position and prevented from rotating.

In operation, when let-off rolls 36 and 38 are rotated forward during the power stroke of pawl 50, bearings 80 will ride in recesses 82 in proximity to second ends 92 of camming surfaces 88, permitting the let-off rolls to draw the prescribed lengths of pile yarns 16 from pile warp beam 14 for forming pile loops 30. However, when the pile yarns exert a torsion force on the let-01f rolls during the indexing stroke of pawl 50 tending to rotate the rolls backward, bearin gs 80 will move into proximity with first ends 90' of camming surfaces 88 and will become wedged in recesses 82 between the camming surfaces and overlapping section 78, to thus lock rotary hub 66 to stationary hub 70 and prevent the let-off rolls from rotating backward.

The locking means also includes a biasing means associated with each of recesses 82 which urges the bearing carried therein toward first end 90, so that rotary hub 66 will be locked immediately to stationary hub 70 whenever the let-off rolls tend to rotate backward. Each biasing means comprises a spring-biased plunger 94 which is carried in a cylindrical recess 96 formed in overlapping section 76 of rotary hub 66. As shown in FIG. 4, plungers 94 extend into recesses :82 adjacent second ends 92 of camming surfaces 88. When rotary hub 66 is rotated forward by driving means 46, bearings 80 will ride against the extremities of plungers 94 in proximity to second ends 92 and thus will be carried freely in recesses 82.

Bra-king means 62 also includes an override means associated with bearings 80 for positioning the bearings in proximity to second ends 92 of camming surfaces 88, so that rotary hub 66 and let-off rolls 36 and 38 may be rotated backward for maintenance or other purposes. The override means includes a cover 98 which is concentrically disposed about overlapping sections 76 and 78, and is journalled for rotation with respect to both of hubs 66 and 70. Cover 98 is held in place by a retainer spring 100 which engages an annular recess 102 formed in the inner periphery of the cover.

Also, cover 98 includes an integral annular plate 104 which is positioned axially adjacent section 76 for retaining bearings :80 in recesses 82. Afiixed to plate 104 are a plurality of pins 106 each of which extends into one of recesses 82 adjacent first end 90 of camming surface 88 and between bearing 80 and side wall 84. When cover 98 is rotated backward in the direction opposite to that of arrows 44, pins 106 will contact and hold bearings 80 in proximity to second ends 92 of camming surfaces 88, to thus permit rotary hub 66 and let-off rolls 36 and 38 to be rotated backward.

A knurled surface 112 is formed on the external periphery of cover 98 to facilitate manual gripping and turning of the cover when it is desired to rotate the let-off rolls backward. When the cover is released, plungers 94 will urge bearings 80 toward first ends 90 of camming surfaces 88 and pins 106 will move back against side walls 84 adjacent first ends 90.

A hand wheel 108 is provided for manually rotating the let-off rolls backward and is afiixed to shaft 64 by a set screw 110.

From the foregoing description it will be apparent that unidirectional braking means 62 is an economical and eflicient improvement for conventional terry looms which effectively precludes the pile warp let-off mechanism of such a loom from operating in a backward direction while the loom is weaving terry cloth. This result insures that the pile loops formed on the face of the terry cloth will be of a uniform height.

The unidirectional braking means operates essentially automatically during the weaving operation and does not require the constant attendance and frequent adjustment of a skilled operator as do other let-off mechanism control devices, such as friction braking device 54.

In addition, unidirectional braking means 62 includes an override means which permits the let-off rolls to be rotated backward when desired.

It is recognized that various modifications of the preferred embodiment of the invention will occur to those skilled in the art. Therefore, the scope of the invention is to be limited solely by the scope of the appended claims.

I claim:

1. In a loom including, a frame, a weaving means supported by the frame for weaving terry cloth having pile loops formed on the face thereof, a pile warp beam rotatably supported by the frame for holding a supply of pile warp yarns, a pair of shafts journalled in the frame, a pair of interconnected pile warp let-off rolls affixed to said shafts for drawing the pile yarns from the pile warp beam and feeding said yarns to the weaving means, and drive means connected to said shafts for intermittently rotating the let-off rolls so that prescribed lengths of the pile yarns will be drawn intermittently from the pile Warp beam and fed to the weaving means for forming the pile loops; the improvement comprising, a unidirectional braking means associated with the let-off rolls for permitting the rolls to be rotated in the direction for drawing the pile yarns from the pile warp beam and preventing the rolls from being rotated in the opposite direction. so that the lengths of the pile yarns intermittently drawn from the pile warp beam by the let-off rolls will be uniformly of the prescribed length and the pile loops formed in the terry cloth will be of a uniform height.

2. A loom as recited in claim 1, wherein said unidirectional braking means includes an override means for permitting the let-ofi rolls to be rotated in the direction op posite to the direction for drawing the pile yarns from the pile warp beam.

3. A loom as recited in claim 1, wherein said unidirectional braking means comprises a stationary hub secured to said frame, a rotary hub aflixed to one of said shafts and rotatable with respect to said stationary hub, each of said hubs having a section which concentrically over laps a section of the other of said hubs, and locking means interposed between the overlapping sections of said hubs for locking the rotary hub to the stationary hub whenever a force is exerted on the let-off rolls tending to rotate the rotary hub and let-off rolls in the direction opposite to the direction for drawing the pile yarns from the pile warp beam.

4. The l-oom as recited in claim 3, wherein the overlapping section of said rotary hub is disposed concentrically about the overlapping section of said stationary hub.

5. A loom as recited in claim 3, wherein said unidirectional braking means further comprises an override means associated with said locking means for releasing the look ing means and permitting the rotary hub and let-off rolls to be rotated in the direction opposite to the direction for drawing the pile yarns from the pile warp beam.

6. A loom as recited in claim 3, wherein the overlapping section of the rotary hub has a plurality of recesses formed therein each opening toward the overlapping section of the stationary hub and being partially defined by a camming surface which faces the overlapping section of the stationary hub, said camming surfaces each extending between a first end oriented toward the direction of rotation of the rotary hub for drawing the pile yarns from the pile warp beam and a second end oriented toward the opposite direction of rotation of the rotary hub, said camming surfaces sloping away from the overlapping section of the stationary hub as said surfaces extend from said first ends to said second ends so that said first ends are closer to the overlapping section of the stationary hub than said second ends; and said locking means comprises a plurality of bearings each having a substantially circular-shaped cross-section, one of said bearings being carried in each of said recesses and the cross-sectional diameter of said bearings being greater than the distance between said first ends of the camming surfaces and the overlapping section of the stationary hub and less than the distance between said second ends of the camming surfaces and the overlapping section of the stationary hub; whereby when the rotary hub and let-off rolls are rotated forward in the direction for drawing the pile yarns from the pile warp beam the bearings will be carried in the recesses in proximity to said second ends of the camming surfaces and will have no effect on the forward rotation of the rotary hub and let-oif rolls, and when a force is exerted on the let-off rolls tending to rotate the rotary hub and let-off rolls backward in the direction opposite to the direction for drawing the pile yarns from the pile warp beam the bearings will become wedged in the recesses in proximity to said first ends of the camming surfaces between the camming surfaces and the overlapping section of the stationary hub and will lock the rotary hub to the stationary hub to thereby prevent the rotary hub and let-off rolls from rotating backward.

7. A loom as recited in claim 6, wherein said bearings are cylindrical-shaped.

8. A loom as recited in claim 6, wherein said locking means further comprises a biasing means associated with each of the recesses for urging the bearing carried therein toward said first end of the camming surface, so that the rotary hub will be locked immediately to the stationary hub whenever a force is exerted on the let-off rolls tending to rotate the rotary hub and let-off rolls backward.

9. A loom as recited in claim 8, wherein each said biasing means comprises a spring-biased plunger carried in the overlapping section of the rotary hub and which extends into the associated recess adjacent said second end of the camming surface.

10. A loom as recited in claim 8, wherein said unidirectional braking means further comprises an override means 8 associated with the bearings for positioning the bearings in proximity to said second ends of the camming surfaces and preventing the bearings from becoming wedged between the camming surfaces and the overlapping section of the stationary hub, so that the rotary hub and let-off rolls may be rotated backward.

11. A m as recited in claim 10, wherein said override means comprises a plurality of members extending into said recesses and selective means to urge said members against said bearings to retain said bearings in proximity to said second ends of the camming surfaces and prevent the bearings from becoming wedged between the camming surfaces and the overlapping section of the stationary hub.

12. A loom as recited in claim 11, wherein said selective means comprises a cover disposed concentrically about the overlapping sections of the hubs and journalled for rotation with respect to the hubs, and said members comprise a plurality of pins affixed to said cover each extending into one of the recesses adjacent said first end of the camming surface, so that when the cover is rotated in the direction opposite to the direction for drawing the pile yarns from the pile warp beam the pins will be urged against said bearings.

13. A loom as recited in claim 1, wherein a bi-directional frictional braking means is also associated with said let-off rolls.

References Cited UNITED STATES PATENTS 2,250,833 7/1941 Hill 139-25 2,562,196 7/1951 Lewis 188-8284 3,171,348 3/1965 Wetzer 18882.84 3,351,096 11/1967 Burgess et a1. 139-25 HENRY S. JAUDON, Primary Examiner.

US. Cl. X.R.

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