US2623345A - Tension controlling means for strip material - Google Patents

Description

Diec. 30, 1952 G. T.w. GRIEVE 2,623,345

TENSION CONTROLLING MEANS FOR STRIP MATERIAL Filed June 30, 1951 3 Sheets-Sheet 2 Inventor Attorney Dec. 30, 1952 G. 1'. w. GRIEVE TENSION CONTROLLING MEANS FOR STRIP MATERIAL Filed June 30, 1951 3 Sheets-Sheet 5 WNW/7M Inventor Patented Dec. 30, 1952 ,UNITED STATES PATENT OFFICE TENSION CONTROLLING MEANS FOR STRIP MATERIAL George Thomas Wilson Grieve, Woolwich, London, England, assignor to British Insulated Callenders Cables Limited, London, England,

' a British company Application June 30, 1951, Serial N0. 234,505

In Great Britain July 7, 1950 vthere is frequentlyr the necessity for keepingthe lSome cases require a greater degree of accuracy and'constancy lin this than others and in some cases there is more tendency to variation of tension and variation over a larger range than in others. One of the most diicult cases, from both these points of view, is foundin the lapping of paper tape on to an electric conductor for the purpose of building-up a body of insulating material. It is with this case that `the invention is primarily concerned but it is also applicable to other cases.

In lapping 'paper tape on to an electric con ductor the tape in the form of a flat spiral coil orv pad is held on a spindle between discs and the whole is rotated bodily about the' axis of the cable,

Vthe paper tape being drawn off over suitable guides so as to be lapped helically with precision about the conductor. Tension is applied to the tape `at the pad holder by the bearing friction and by a brake. It is also applied-by friction at the guides The total tension is produced by a combination of these eiects in varying proportions according to the design of machine andto the particular conditions of operation.

Bythe nature of this case there are two principal causes operating to produce variation in the tension in the paper. One of these is the change in theI diameterof the pad; a constant tension in the paper at the periphery of the pad obviously cannot 4be balanced'by a constant braking force on' the Apad carrier' as' the radius of application of the' tensionA to thepad varies through a large rangeA -The other principalcause is the change of centrifugal loading on the bearings of the `pad and of the guides as the speed of rotation about the axis of the cable changes during starting and stopping of the machine.

The present invention deals with the first of these two causes and it will be seen'that it is applicable, not only to the particular case for which it is primarily intended but also to other cases'where vthe diameter of the coil varies during the Vwithdrawing of the flexible member from it.

vFor 'convenience the flexible member will be r hereinafter referred to by the Word tapa it beingunder'stood thatv this word is only used as illustrative of a general class of long flexible articles. y

vIn accordance with the invention the loading 6 Claims. (Cl. 57--3) lit) 2 of the brake on the carrierV of'thecoil is adjusted by means of amechanicalrelay device, the action of which is under the control` of the tension'which 4exists in the tape. This relay action is provided by a rotary shaft in continuous motionwhich can be coupled from time to time with means for adjusting the brake, the time of coupling-'and the sense of its eiect in producing adjustment being determinedby the action of a feeler member which is subjected to the tension of the tape. A preferable arrangement is one inwhich the shaft carries 4or actuates acam or other means of producingreciprocating" motion having a free interval in each cycle of movement and the adjustment of the brake loading is produced by a turning of a member, such as a nut or cam, 'which may be moved in either sense by the action of pawls and ratchet wheels, the pawls being coupled to a reciprocating member or brought into association with the ratchet wheel, during free intervals.' by the feeler member under the iniiuence of the tension in the tape.

The feeler arrangement may consist of a roller round which the tape passes andwhich is carried at the end of a swinging lever, the position'of which is determined by the `balance between the tension onthe tape acting on the roller and the force of a spring acting on the lever in opposition to the tension.'y The tape is preferably guidedby the aid of two other rollers so that it passes in a narrow loop from these two rollers round the feeler roller which is in the end of the loop, so that ther direction of the force exerted by the tension in the'` tape does not vary appreciably with' the movement of the feeler roller. The spring force may be providedby an independent spring acting on a pivoted lever or by the inherentl springiness of a lever which is rmlyanchored at the end remote from the feeler.

With a controlling arrangement in accordance with the invention, the adjustment of the brake loading, while it may vary to some extent in both senses, will, in general, change as lthe coil -of paper decreases in diameter in such a way that the loading or the brake decreases progressively. It will, accordingly be necessary to reset the loading when a new coil is placed in position. This can be done by hand or automatically and in the latter case may result from someaction involved in the placing of new'coilin position. For instance, when the coil carrier `or a movable part thereof is removed from or replaced-in position with or after the insertion of the new coil, its movement out'of or into place may produce by means of suitable gearing the readjustment of the bra-ke loading to the approximate value required.

In a machine for lap ing paper tape on to an electric conduct-or in which the coil of paper is carried in rotation about the axis of the machine while the conductor moves forward along that axis, the mechanical relay device can be provided by a cam which is mounted about the axis of the machine and is either held stationary or is rotated at a speed different from, but proportional to, that of the head carrying the coils of paper. The cam is shaped to provide a part or parts at which it is disengaged from its follower to give free intervals in the transmission.

An example of a machine for lapping paper tape onto an electric conductor Will be described `as an example with reference to the accompanying drawings in which Figure 1 is an elevation of part of the machine and Figure 2 is a side elevation partly in cross-section of some parts of the machine shown in Figure l. Figures 3 to 6 represent parts of the arrangement shown in Figure l, Figure 3 shows also an arrangement for driving the machine, and Figures to 6 represent details to a larger scale.

The machine is of the type in which the coil I of the paper tape rotates bodily, in a suitable carrier, about the axis of the conductor with its central plane substantially radial to the axis of the conductor. The coil I is mounted between two metal discs 2 and 3 (Figure 2) on a hub Il carried by a spindle 5. The spindle 5 is freely supported in b-all bearings 6 at the end of a vertical arm 'i rigidly mounted on the end of a horizontal spindle 8. rThe horizontal spindle 8 is securely anchored by nuts 9 to a support It which rotates about a fixed tubular hub I I. The support I is fixed to a sleeve 52 surrounding the xed hub I I and mounted for rotation in a bearing 53 which is supported on a pedestal 55. The drive to the rotating sleeve 52 is derived from a motor 55, through a gear box 55, driving shaft 51, gear wheel 58, driving chain 59 and driven gear wheel 50 fixed to the sleeve 52. The conductor onto which the paper is being lapped passes centrally through the tubular hub II.

A toothed ring I 2 secured to the hub II by a pin SI meshes with a gear wheel I3 mounted coaxially with a second smaller gear wheel I4 on a spindle i5 fixed to the rotating part of the machine. The spindle I5 is supported in a bearing plate 52 which is xed to a plate 22 attached to the sleeve 52. The smaller gear wheel It drives a second toothed ring I5 which is loosely mounted on a bearing 53 in suitable guides on the hub H. .It will be seen that the two gear wheels I3 and it being fixed together act as a reduction gear to drive the wheel I5 at an angular speed less than that of the sleeve 52 and asso ciated rotating parts.

The wheel It is formed with a tubular extension I 'I to which is secured a cam ring i8. A tappet rod I9 is freely mounted for longitudinal reciprocation in guides 2G supported on the plate 22 which rotates with the support I5. Fixed to the lower end of the rod E9 is a roller 23 which is forced against the surface of the cam I by spring ZI and xed to the upper end of the rod I3, there isa flat bracket 2d on which slides a block 25 fixed at I5? toa horizontal rod 2d.

The position of the block 25 is controlled the horizontal rod 2G which passes freely through. holes 66 in the vertical arms G5 of the bracket 2li and is coupled at its opposite end to a pivot-ed arm 27 carried by the arm "i, The coupling bemake contact with the roller 2S.

tween the horizontal rod E5 and the pivoted arm `2"I is a pivot 55 which allows the rod 25 to move freely in a vertical plane. The arm 2 is biassed by' a spring (not shown), which tends to rotate it in a clockwise direction. Paper tape passes from the coil I over a guide roller 29 secured to the arm 1, then over a roller 30 carried at the lower end of the arm 2"! and back under a third roller 3| to further guide rollers, not shown, which direct it onto the conductor. rlhe arm 21 and roller 3Q constitute a feeler member" responsive to the tension of the tap 28. Increase in tension in the tape 28 will tend to move the `roller 30 towards the arm '1, hence pivoting the arm 2l, against the biassingT spring, in an anticlockwise direction to force the block 25 towards the lefthand end of the bracket 25. Similarly, a decrease in tension in the tape will ailow the arm 2l to rotate in a clockwise direction under the action of the biassing spring to move the block 25 towards the right-hand end of the bracket 2t.

rIwo opposed ratchet wheels 32 `and 33 (that is wheels having their teeth arranged in opposite senses) are loosely mounted, integrally with each other and with a bevel gear wheel 34, on the horizontal spindle The bevel gear wheel 3 drives a smaller bevel gear wheel 3'! which is attached to a cam 33. The ratchet wheel E2 is rotatable by a pawl 35 `and the ratchet Wheel 35i by a pawl 35 (see Figure 2). The tappet rod i5 is continually recipracted under t-he action of the cam i8 when the sleeve 52 and the parts carried on it, including the paper coil I are ro tating about the conductor.

When the block 25 is in a central position on the bracket 2li, as shown in the drawing, it does not make contact with either of the pawls 35 and 3E during the reciprocating movement of the rod I9 but when it is moved to the right or left as tension in the tape 28 varies, it makes Contact, as the rod IS moves upwards, with one of the pawls 35 and 3S and rotates the corresponding ratchet wheel about the spindle 8. The horizontal rod 26 is long in comparison with the range of movement of the tappet rod I!) so that the path of the block .25 approximates suniciently to a straight line.

The major part of lthe periphery of the cam ring I8 is circular, as shown at 63 in Figure and when this part is uppermost the ring does not The eiective lobe 58 of the cam ring i8 extends over a rela-- tively small are as shown in Figure 5. The downward movement of the tappet rod I9 .under the inuence of the spring 2| is limited by the engagement on the top of the upper xed guide 25v of the underside of a nut l5 whichl locks the l connection between the tappet rod and the bracket 2a. This ensures that there is a free interval in each cycle of movement of the tappet I9 when it is at rest in its lower position. In this position the block 25 is free to move from end to end of the bracket 213 with movement of the arm f l2l unimpeded by lower ends of the pawls 35 and 35.

of thecam 38, the position shown in'Figure 4. the maximum'braking isappliedftol the drum'v 39 by the shoe 40 under' 'theactonof the spring 42. Asthe cam 33 is 'rotated counter-clockwise as seen in Figure 4, under the action of thepawl 35 and its associated ratchet 32, the brakingV effect is decreased by the movement of the brake rod 44 towards the righthand as seen in the drawing; under the action of the other pawl 36 and its associated ratchet Wheel 33, thecam 38 is rotated inthe reverse direction so that the braking is increased. The operative surface of the cam 38 is of spiral shape thehighestand lowest points 1I and V'12 respectively being connected by a radial step 13.

At the start of a lappingoperation when a full coil of tape is loaded onthe hub 4,the cam 38 is initially set with its lo'west part 12 adjacent ther'end of the brake rod '44* so 4that maximum braking is applied; Generally asthe tape is--un- Wound fromv the coil, it will be necessary for progressively decreasing braking to` be applied to the drum 39 to maintain a uniform tension in the tape 28as` the diameter of the coil decreases. As*4 the tension in the strip tends to increase 'with the Vdecrease in coil diameter the braking eiect of the shoe "40 on the drum 39 will be appropriately altered, to maintain the correct tension, by the pivoting of the feeler member 21 and the sliding of the block 25 in the bracket 24 to cause the reciprocating tappet rod I9 to reciprocate the `appropriate paw135. Should the tension in the strip tend to decrease due for instance to uneven winding of the coil'th'e reverse effect will be `obtained by-means of the other pawl 36.

Means are provided for automatically rotating the cam 38 into a position-in which its lowest part is adjacent the end of the brake rod 34 whenever a new coil of paper is loaded onto the hub 4. This is effected by the folowing mechanisrn. A spindle 45 (Figure 2) passes centrally through the spindle 5 on which the coil is mounted. The spindle 45 is associated with means, not shown, as described in the specification of co-pending U. S. Patent application Serial No. 234,492 led June 30, 1951 of Ripley, which serves for releasing a spent coil from and locking a new coil on the hub 4. During this operation the spindle 45 is rotated in a clockwise direction and then in a counter clockwise direction as seen in Figure 1. A disc 46 mounted on the end of the spindle 45 inside the brake drum 39 carries a projecting pin 41 which, upon this rotating movement of the spindle 45, is brought into contact with a spring 48 mounted on a vertical arm 49. The arm 49 is rigidly attached to a horizontal rod 50 adapted to bear against a pin 5I projecting upwards from the upper face of the cam 38. The rotation of the spindle `45 in a clockwise direction under these conditions, forces the rod 50 from right to left and rotates the cam 38 to a position in which its lowest part bears against the end of this rod. Thus this action resets the brake 40 into a position into which it exerts the maximum braking force on the drum 39.

In normal operation of the machine the successive coils of strip which are used will have approximately similar characteristics of diameter and winding tension. In normal running therefore the brake rod 44 will be in contact with the cam 38 at or near the highest point 13 when a coil requires replenishing. The angular position of the pin 5I relative to this point v13, -the diameter of-A the pin; `its' radial distance from' the centre of rotationbf'-the cam, and the limit-of movement ofthe end 15 of'fthe horizontal rod 50 towards the lefthand are so selected that at the end of the movement of the rod 59 the cam will have turnedto theV position in which the endV of `the brake rod`44 will fall from the highest pointf13to the lowest point 12` In practice the coil of strip will be replenished before the highest pointv 13 of the cam is reached and the automatic resetting of the cam will take place when the pin 5I comes to a nal position anywhere within the arc"14. If for any reason the pin lies outside that arc thecam will be turned to the appropriate position by the tension controlling mechanism after rotation-of the machine is resumed.

What I claim as my invention is:

1. Apparatus for controlling thetension in a long flexible member while it is being unwound from a carrier comprising a brake retarding said carrier, a shaft driven in continuous rotary motion throughout the winding or unwinding operation, means for adjusting said brake, `a.

feelermember subjected to the'tensionof said flexible member and means controlledlby said feeler member for intermittently coupling said shaft with said brake adjusting means toY effect the adjustment Aoffthe brake necessary when said tension changes from the desired value.

2. Apparatus forcontrolling the tension Ain a long ilexible member while it is being unwound from a carrier comprising a brake retarding saidcarrier, a shaft driven in continuous rotary f motion throughout the unwinding operation; a

reciprocating member driven by saidshaftgftwo opposed ratchet wheels;V a rotatable member adapted to be driven in ,af direction to decrease said braking by the iirst of said ratchet wheels and in a direction to increase said braking by the second of said ratchet wheels, first and second pawls one associated with each of said ratchet wheels, a feeler member subjected to the tension of said iiexible member and adapted to adjust said brake by coupling said first pawl to said reciprocating member when the tension increases excessively and said second pawl to said reciprocating member when the tension decreases excessively.

3. Apparatus for applying a lapping at a substantially uniform tension of a long ilexible member to a second member passing through said ap- "paratus comprising a carrier 4for said flexible member, means for rotating said carrier bodily about said second member, a brake ret-arding the delivery of said flexible member from -said carrier, a reciprocating member driven in such a way that there is a free interval in `each cycle of its movement by said rotation of said carrier about said second member, two opposed ratchet wheels, a rotatable member adapted to be vdriven in a directicn to decrease said braking by the rst of said ratchet wheels and in a direction to increase said braking by the second of said ratchet wheels, iirst and second pawls one associated with each of said ratchet wheels, a feeler member subjected to the tension of said iiexible member and adapted to adjust said brake by bringing said rst pawl into association with said reciprocating member during a free interval when the tension increases excessively and bringing said second pawl into association with said reciprocating member during a free interval when the tension decreases excessively.

4. Apparatus for applying a lapping at a sub- 'stantiallyi uniformjtension of a long `iiexible member to a second member passing through said apparatus comprising a carrier for said flexible member, means for rotating said carrier bodily about said second member, a brake retarding the delivery of said iiexible member from said carrier, a reciprocating member driven in such a way that there is a free interval in each cycle of its movement by said rotation of said carrier about said second member, two opposed ratchet wheels, a rotatable member adapted to be driven in a direction to decrease said braking by the first of said ratchet Wheels and in a direction to increase said braking by the second of said ratchet Wheels, first and second pawls one associated with each of said ratchet wheels, a feeler member subjected to the tension of said iexible member and adapted to adjust said brake by bringing said rst pawl into association with said reciprocating member during a free interval when the tension A increases Iexcessively and said second pavvl into association with said reciprocating member during a free interval when the tensiondecreases excessively and means for automatically resetting said brake to the position of maximum braking whenever a fresh supply of said flexible member is loaded onto said carrier.

5. Apparatus for lapping at a substantially uniforml tension, a Flexible tape onto a conductor, comprising a carrier for a coil of said tape, means for rotating lsaid carrier and coil bodily about said conductor, a brake retarding the unwinding of said tape from said coil, a reciprocating member driven by said rotation of said carrier about said second member, two opposed ratchet Wheels, a rotatable member adapted to be driven in a direction to decrease said braking by the rst of said ratchet Wheels and in a direction to increase said braking by the second of said ratchetv wheels, first and se'cond pawls one associated with each of said ratchet Wheels, a feeler member subjected to the tension of said exible member and adapted to adjust said brake by coupling sai-d rst pawl t0 said reciprocating member when the tension increases eX- cessively and said second pawl t0 said reciprocating member when the tension -decreases excessively.

6. Apparatus for lapping at a substantially uniform tension, a iiexible tape onto a conductor, comprising a carrier for a coil of said tape, means for rotating said carrier and coil bodily about said conductor, a brake retarding the unwinding of said tape from said coil, a reciprocating member driven in such a way that there is a -free interval in each cycle of its movement by said rotation of said carrier about said second member, tvvo opposed ratchet wheel-s, a rotatable member adapted to be driven in a direction to decrease said braking by the rst of said ratchet wheels and in a direction to increase said braking by the second of said ratchet Wheels, first and second piawls one associated with each of said ratchet Wheels, a feeler member subjected to the tension of said exible member and adapted to adjust said brake by bringing said irst pawl into association with said reciprocating member during a free interval when said tension increases excessively and bringing said second pawl into association ywith said reciprocating member during a free interval when `said tension decreases excessively, and means for returning said rotatable member to the position of maximum braking actuated when a new coil is placed in position on said carrier. f

GEORGE THOMAS WILSON GRIEVE.

N o references cited.

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