Apparatus for imparting a predetermined value of twist to a material

Claim 2

Apparatus for imparting a predetermined twist to a multistrand cable during takeup comprising: a. a cable twisting unit including a frame mounted for rotation about the axis of said cable and including also a torque imparting means having an element of endless length and coursing a winding path of a plurality of helical turns around said cable and in engagement with said cable for transmitting torque to said cable to provide a predetermined twist in the said cable; said endless element being movable with respect to the frame along said winding path, and b. braking means associated with said cable twisting unit and opposing movement of the endless element along said winding path to apply a controlled torque to the cable by said endless element.

Claim 3

The apparatus for imparting a predetermined twist in said cable claimed in claim 1 wherein the apparatus includes a twist sensor to sense variations from said predetermined twist to control said braking means to vary the twisting torque in response to said variations.

Claim 4

The apparatus for imparting a predetermined torque in said cable claimed in claim 2 wherein said twist imparting means is of flexible cylindrical material.

Claim 5

The apparatus for imparting a predetermined torque in said cable claimed in claim 2 wherein the twist imparting means are made of flexible cylindrical material and the cable twisting unit includes first means to direct said torque imparting means onto said cable and second means to receive said torque imparting means from said cable.

Claim 6

The apparatus for imparting a predetermined twist in said cable claimed in claim 4 wherein said first means is a sheave and said second means is also a sheave, and the twisting unit includes also slack compensation means, in engagement with said torque imparting means and responsive to variations in the length of the winding path of said torque imparting means to maintain substantially constant tension in said torque imparting means.

Claim 7

The apparatus for imparting a predetermined twist in said cable claimed in claim 5 wherein the slack compensation means comprises a sheave in engagement with said torque imparting means and moveable longitudinally of the axis of said cable and responsive to variations in the length of the winding path of said torque imparting means to maintain substantially constant tension in said torque imparting means.

Claim 8

The apparatus for imparting a predetermined twist in said cable claimed in claim 5 wherein said braking means is a magnetic clutch and said twist sensor comprises first means to sense variations in the lay of said cable and second means connected with said magnetic clutch to vary the flux of said magnetic clutch in response to variations in said lay.

Claim 9

The apparatus for imparting a predetermined twist in said cable claimed in claim 7 wherein said twist sensor comprises photocell means to sense variations in the lay of said cable and circuit means connected to said magnetic clutch and actuated by said photocell means to vary the flux of said magnetic clutch in response to variations in said lay.

Claim 10

The apparatus for imparting a predetermined twist in said cable claimed in claim 5 wherein the first sheave is positioned to direct the torque imparting means on to the cable at an acute angle to the axis of the cable.

Claim 11

The apparatus for imparting a predetermined twist in said cable claimed in claim 9 wherein the acute angle varies between 12* and 23* .

Claim 12

The apparatus for imparting a predetermined twist in said claimed in claim 2 wherein there are: a. first and second cable torque imparting means mounted on the frame and diametrically opposite one from the other for common orbital rotation about the axis of said cable and each including an endless length element of flexible cylindrical material coursing a winding path of a plurality of helical turns around said cable and in engagement with said cable transmitting torque to said cable to provide a predetermined twist in said cable, each cable torque imparting means including a first sheave to direct the endless length element onto said cable, a second sheave to receive said endless length element from said cable, a third sheave adapted to receive said endless length element from said second sheave and to guide said endless length element to said first sheave and movable longitudinally of the axis of said cable in response to variations in the length of the winding path of said endless length element to maintain substantially constant tension in said endless length element; b. the braking means including magnetic clutch means associated with said first and second cable torque imparting means to vary the torque transferred by each of said endless length elements to said cable; and c. the twist sensor having first means to sense variations in the lay of said cable and second means connected with said magnetic clutch means to vary the flux of said magnetic clutch means in response to variations in said lay.