US3470921A

US3470921A - Letoff apparatus for textile machine

Info

Publication number: US3470921A
Application number: US675985A
Authority: US
Inventors: Raymond L Booth
Original assignee: North American Rockwell Corp
Current assignee: Draper Corp; Boeing North American Inc
Priority date: 1967-10-17
Filing date: 1967-10-17
Publication date: 1969-10-07
Anticipated expiration: 1986-10-07
Also published as: CH478270A; JPS5020182B1; BR6803166D0; FR1586303A; BE722396A; GB1233740A

Description

Oct. 7, 1969 R. L. BOOTH LE'IOFF' APPARATUS FOR TEXTILE moms .2 Sheets-Sheet 1 Filed Oct. 17. 1967 R 0 T N E V N I RAYMONDLBOOTH Rm 22W ATTORNEY R. L. BOOTH LETOFF APPARATUS FOR TEXTILE MACHINE 2 Sheets-Sheet 2 Filed Oct. 17, 1967 INIVENTOR. RAYMOND L.BOOTH flM [KW ATTORNEY United States Patent O U.S. Cl. 139109 8 Claims ABSTRACT OF THE DISCLOSURE An apparatus for regulating the speed of rotation of warp beams or the like to maintain a uniform tension on the threads or other sheet material being delivered there from. A sensitively controlled brake for permitting variations in the rotating speed of a letoff beam in response to tension changes throughout the complete full-to-emptv cycle.

FIELD OF THE INVENTION This invention relates to a tension control means for the letotf mechanism of textile machinery by which threads or other sheet or web material are delivered from a yarn beam or other wound source for further fabrication. It more particularly relates to a brake mechanism for regulating the speed of rotation of such a beam to maintain a near-constant tension upon the threads or other material.

In looms, knitting machines and other textile machines, the letoff for the yarn or sheet material must be synchronized with the take-up mechanism while maintaining a substantially constant tension on the material. Various factors combine in adversely affecting the control of tension such as the continually decreasing beam diameter and the shedding and beatup operations. Letolfs are known in the art which, by gearing and ratchet devices, intermittently release the yarn beam for a few degrees of rotation. These may in addition include mechanism for increasing the amount of rotation permitted as the beam diameter decreases. Letolfs have also employed frictional braking forces to restrain the beam rotation against the pull of the takeup mechanism. With these it has been necessary to make adjustments from time to time to overcome the variation in tension as the beam size decreases. To provide a near-constant tension, letolfs have required considerable mechanism and have been expensive to manufacture and to maintain in adjustment. This invention overcomes the disadvantages of the above stated letoff controls and discloses a means which is sensitive and responsive to tension changes and which is comparatively inexpensive and easily applied to existing machines.

SUMMARY This invention provides a letotf controlling mechanism whereby a caliper-type disc brake permits 'stepless rotation in response to increases in the tension applied to the yarn feeding from a beam.

It is a general object of the invention to devise an improved letofi control which shall be less expensive to manufacture and maintain than those presently known.

It is a further object of the invention to devise a letolf controlling mechanism for maintaining a uniform warp tension from full to empty beam by means of a calipertype disc brake actuated by either hydraulic, mechanical or pneumatic forces.

It is another object of the invention to devise a letoif control which shall be sensitive to minute changes and will restrict the beam against overrunning a preset tension level.

These and other objects of the invention will become apparent as further details are disclosed.

3,470,921 Patented Oct. 7 1969 BRIEF DECRIPTION OF THE DRAWINGS The invention will be described in greater detail by reference to a specific embodiment thereof as shown in the accompanying figures of drawing, wherein:

FIG. 1 is a side view in perspective of a loom having the invention applied thereon;

FIG. 2 is a plan view of the caliper-type disc brake device shown in FIG. 1;

FIG. 3 is a perspective view showing the stationary brake shoe;

FIG. 4 is an exploded view of the disc brake portion having the movable brake shoe; and

FIG. 5 is a more detailed view of a portion of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Now referring to FIGS. 1 and 5, a portion of a loomside 20 is shown with the apparatus of the invention applied at the left-hand side of a loom for weaving. It will be understood from the following explanation that the device is applicable also to a warp knitting machine or other machines where threads or sheet material are letoff from a beam or reel under controlled tension. One end of a warp beam 21 and a beam gear 22 are shown firmly fixed to a shaft 23 which is supported for rotation in a bearing 24 held by the loomside 20.

A vibrating whip roll 25 is carried for rotation by two pivotally mounted arms 26 (one shown) supported by bracket 27 which is bolted to the loomside 20. A plurality of warp yarns 28 is drawn over the whip roll 25 as a web in a well known manner for further fabrication and is arranged to bear upon the whip roll with a desired tension which may vary according to the fabric construction. Means for presetting the tension value will be explained below.

A stub shaft 29 which pivots the arm 26 also has keyed thereto an upwardly angled lever 30. As viewed in FIGS. 1 and 5, it will be seen that, as tension is increased upon the yarn 28, the roll 25 will be depressed and thus pivot the lever 30 clockwise and as the tension is decreased the reverse motion will occur. At a point 31 on the lever 30, at a distance from the pivoting shaft 29, is fastened one end of a shaft 32 in a position to be moved slightly longitudinally by the pivoting action of the lever 30. The shaft 32 extends freely through a bracket 33 fixed to the loomside 20 as by a bolt 34. A compression spring 35, through which shaft 32 also extends, bears upon the bracket 33 with tension being applied by a thumb screw 36 threaded upon the shaft 32 allowing optimum tension to be preset by varying the location of the thumb screw 36. The lower end of the shaft 32 has a ball-joint end 37 pivotally fastened to one arm of a bell-crank lever 38 which pivots on a screw 39 secured to the loomside 20 (FIG. 1).

The downwardly extending arm 40 of the bell-crank lever 38 is slotted to receive an end of an activating rod 41 which extends generally horizontally and whose movement will be controlled by the pivoting action of the bellcrank lever from indications of variations in tension upon the whip roll 25. A collar 42 is slidably carried on the rod 41 rearwardly of the arm 40 and retains a compression spring 43 which encircles the rod 41 and is variably compressed by a thumb screw 44 bearing upon a collar 45. The rearward end of the rod 41 is pivotally connected at 46 to an activating lever 47 which is supported pivotally -by a master cylinder assembly, generally designated 48. The master cylinder assembly 48 may function by mechanical or pneumatic means or may, as is shown in the preferred embodiment, contain a full supply of hydraulic brake fluid for transmitting changes in pressure. This type of assembly and others are available commercially such as those sold by H-H Products Company, Inc., of Milwaukee, Wis. The master cylinder assembly 48 includes a housing 49 with a piston 50 movably contained therein, positioned so as to be pressed and released by the activating lever 47 in its pivotal movement.

A length of tubing 51, also containing brake fluid, is connected between the cylinder assembly 48 and a calipertype disc brake, generally designated 52 which is securely bolted to a bracket 53, fastened to the loomside 20 (FIG. 1). A caliper-type disc brake satisfactory for the purposes of the invention is that furnished by the H-H Products Company, Inc., set forth above. This type brake includes opposingly disposed interconnected housings 54 and 55 (FIG. 2). The housing 54 in this instance has a fixed brake shoe 56 secured in place by a screw 57 (FIG. 3). The second housing 55 includes a brake shoe 58 movable toward and away from the brake shoe 56 within the space separating the

housings

54 and 55 and within which space a rotatable disc 59 is adapted to move in a position to be compressed between the faces of the brake shoes 56 and 58 (FIGS. 1 and 2). The brake shoe 58 is fastened by a screw 60 to a hydraulic piston 61 having a mounted oil seal ring 62 (FIG. 4). It will be understood that as pressure is exerted against the piston 50 a corresponding response will actuate the piston 61 which will urge the brake shoe 58 against the disc 59 and apply a frictional contact. The invention may include a disc brake having two movable brake shoes 58 and two housings 55, in which case pressure would be exerted against the disc 59 from opposing sides.

The disc 59 is keyed to a shaft 63 which is journalled through the loomside 20 for free rotation. At the inward end of the shaft 63 is fixed a pinion 64 meshing with the beam gear 22 (FIG. 1). The shaft 63 and pinion 64 provide a positive rotating relationship between the yarn beam 21 and the disc 59.

The housing 55 is provided with bleeder screws 65 and 66 for threading into pressure venting holes 67 and 68 for easy pressure adjustment (FIG. 4).

In operation, a desired warp tension is set upon the warp yarns 28 and counterbalanced by adjusting compression spring 35. For pressure control, the spring 43 is adjusted to exert suflicient hydraulic pressure through the activating rod 41 and activating lever 47 to the master cylinder 48. This should exert a clamping pressure on the disc 59 which will restrain the shaft 63 from rotational movement. Any decrease in torque at the shaft 63 will be in proportion with decreases in warp beam diameter from full to empty beam. Minute changes in warp tension will affect the load rate of the spring 35 and, through the above explained linkage, hydraulic pressure will be increased or decreased which will result in a greater or lesser torque at the disc brake 52 and disc 59.

The instant invention achieves the objectives set forth by providing inexpensive and easily applied mechanism whereby instantaneous response to small tension variations will maintain the material being letolf from a beam at a preset tension level.

While one embodiment of the invention has been disclosed, it is to be understood that the inventive concept may be carried out in a number of ways. This invention is, therefore, not to be limited to the precise details described, but is intended to embrace all variations and modifications thereof falling within the spirit of the invention and the scope of the claims.

I claim:

1. In a means for maintaining uniform tension on material being Withdrawn from a rotatable beam which includes (a) a suspended material supporting roll pivotally movable in response to tension variations exerted by the material,

(b) means for presetting said supporting roll at an optimum tension against the material comprising a spring biased pressure adjusting rod fastened for reciprocal movement by said supporting roll,

(0) activating means for translating variations in tensions at said supporting roll comprising (1) an activating rod disposed for longitudinal movement effected by said adjusting rod,

(2) a pressure control spring adjustably positioned upon said activating rod, and

(3) an activating lever pivotably connected to said activating rod,

((1) a pressure responsive housing for transmitting indications of tension variation as received from said activating means,

(e) a caliper-type disc brake connected for actuation by said pressure responsive housing, and

(f) a disc supported for rotation between the operating surfaces of said brake, said disc having a positive rotating relationship with said beam.

2. Apparatus as defined in claim 1 wherein said means for presetting said supporting roll further includes a compression spring through which said adjusting rod is adapted to extend, a fixed bracket for restraining one end of said compression spring, and a screw member threaded on said adjusting rod for varying the tension upon said supporting roll.

3. Apparatus as defined in claim 2 which further includes a pivotally supported bell-crank lever having a first arm fastened to said adjusting rod, and a second arm disposed for providing longitudinal motion to said activating rod.

4. Apparatus as defined in claim 1 wherein said housing comprises a fluid-containing master cylinder, and a fluid-displacing piston movable within said cylinder, movement to said piston being provided by the pivotal movement of said activating lever.

5. Apparatus as defined in claim 4 which further includes fluid-retaining tubing interconnecting said master cylinder and said disc brake, actuation of said disc brake being eflected through intermittent increases and decreases in fluid pressure within said master cylinder.

6. Apparatus as defined in claim 5 wherein said disc brake includes at least one movable brake shoe, said brake shoe being actuated toward and away from said disc by means of variations in fluid pressure initiated at said master cylinder.

7. Apparatus as defined in claim 6 wherein said disc is positively driven from the rotation of said beam by means which includes a beam gear mounted on said beam, and a spur gear pinion in mesh with said beam gear and keyed to a shaft supported for free rotation, said disc being keyed to said shaft and rotatable therewith.

8. Apparatus as defined in claim 7 wherein said housing includes a hydraulic master cylinder and piston for initiating pressure variations for transmission to said disc brake.

References Cited UNITED STATES PATENTS 610,784 9/1898 Wolf 139-I09 1,741,300 12/1929 Holmes 139109 2,755,822 7/1956 Hunt 139-409 HENRY S. JAUDON, Primary Examiner U.S. Cl. X.R. 66- 6