FR2546147A1 - Novel device for controlling the tension of a yarn (wire) or of a web (continuous sheet) in the course of being unwound - Google Patents

Abstract

The invention relates to a novel device for controlling the tension of a yarn (wire) or of a web (continuous sheet) in the course of being unwound from a reel (roll), control being obtained by continuously slowing down the rotation of the reel (roll), obtained by jaws 3, 4 gripping a disc 2, the spindle of which is rotationally integral with the said reel (roll). The device is characterised in that provision is made for the jaws 3, 4 to move radially over the disc 2, the said jaws being kept at a certain distance from the spindle 1, this distance being proportional to the external radius of the reel (roll) in the course of being unwound. Application to the formation of a reel (roll) of webs (sheets) for bundles (packs).

Description

Technical area
The present invention relates to a new device for regulating the tension of a continuous wire or sheet during the unwinding of a spool, the regulation being obtained by continuous braking of the rotation of said spool obtained by jaws tightening a disc. whose axis is integral, in rotation, with said coil.

Problem
When unwinding a spool of thread or sheet, it is necessary to store a certain tension in the thread (s) or sheet for the smooth running of the machine and, in particular, to avoid that, during a deceleration more or less brutal of the machine; the reel continues to rotate and the wire (s) or the sheet does not continue to unwind untimely. However, the materials are wound in a spiral and if the reel is braked with a constant torque tensile forces on the wire (s) or the sheet increase as the diameter of the spool during unwinding decreases.

State of the art and disadvantages
For a long time, the coils have been braked with a ribbon brake, that is to say a ribbon, generally in strip form with a lining, braking the upper part of a plste pulley.

 the bacon sheet is anchored upstream of the direction of rotation of the pulley and the force with which it is applied to said pulley is produced by a weight at its other, free end.

 The disadvantage of this device is that it achieves a practically constantly constant torque with the frequencies which have been indiO, llt ^ eS czars ie the preceding paragraph. It should even be added that this couple can be altered by external conditions (humidity, impurity, dust, etc.). In addition, this device is limited to low torque, because if you want to brake more vigorously for a long time, high heat is released and nothing is planned to eliminate it.

 This device has been perfected by using disc brakes cooled by a circulation of heat-transfer liquid, generally water. However, we always brake at constant torque.

 We still have the braking solution by hydraulic coupler with oil cooling.

 We also have the solution of braking by an electric generator whose current we can control. From this point of view, a variation of the couple is conceivable but we arrive at prohibitive costs.

 The present invention has been deemed necessary to solve the problem of reels comprising a large number of pins (up to 6 or 12) for assembling a corresponding number of rolls of paper intended to constitute bundles for mechanography. These bindings are composed of different papers with varying colors or even the interposition of carbon paper. In this case, it is understood that the tinkering torque of each of the pins of the reel must be rigorously controlled to produce a homogeneous bundled sheet coil.

 The present invention is intended to remedy the aforementioned drawbacks to provide a technically and economically valid solution to the problem which has just been raised.

Statement of the invention
The invention is - mainly characterized by the fact that provision is made for a radial displacement of the jaws on the disc, the mean point of application of the clamping of said jaws on the disc being kept at a distance from the axis proportional to the radius outside of the spool during unwinding.

 The jaws can be held so as to move linearly, but it has been found convenient to hold it at the end of a forked arm articulated around an axis parallel to that of the coil and the oscillation of which is controlled by a slave cylinder. to an order taking into account the diameter of the coil. According to a preferred embodiment, the jaws are actuated at the end of rockers articulated on each of the teeth of the fork and actuated by a hydraulic or pneumatic receiving cylinder.

 The enslavement of the radial or quasi-radial movement of the jaws and, in the last case - the movement of the arm, are conveniently carried out, with a proportionality ratio between their distance to the axis of rotation with that of the outside diameter of the coil , equal to 1. In this case, it is practical to control the movement of the arm from mechanical probes. However, it is also possible to carry out radiation detection of the outside diameter of the coil, as is commonly done with current time, for example by a transmitter and a series of photo-sensitive cells or in pneumatic system with controlled air jet or in mechanical system with. pal fear and microswitch.

Solution to the problem, industrial advantage and result
With the device of the invention, it suffices to correctly adjust the displacement of the jaws radially on the disc as a function of the diameter of the coil, and to adjust the force of application of the jaws against this disc to eliminate the drawbacks which have been mentioned. at the beginning of this brief. One thus obtains a constant tension of the threads or of the sheet and, in the case of constitution of rolls intended for the bundle, comprising a large number of sheets wound one on the other in a spiral, one results in a great homogeneity of the roller or of the coil obtained.

 The invention will be better understood with the aid of the description below and which gives a nonlimiting example of practical embodiment which is illustrated by the accompanying drawings.

Brief description of the figures
In these drawings,
Figure 1 is an elevational-schematic view of the device of the invention.

 Figure 2 is a plan view of the same device.

Description of a mode of realization
In the drawings, the spool of wire or sheet is not shown during reeling, but only its axis (1) which is common with its braking disc (2). The disc cooperates with jaws (3, 4) which are provided with conventional packing applied to the lateral faces of said disc (2).

 The invention consists in the fact that provision is made for a device ensuring the radial depiacrment of the jaws (3, 4).

To this end, these jaws are held in stirrups (5, 6) which are located at the ends of the teeth (7, 8) of a forked arm (9) wedged on a shaft (10) itself articulated on bearings (not shown).

 The oscillation of the forked arm (9) is controlled by a jack (11) articulated at (12).

 The jaws (3, 4) are actuated by rockers (13, 14) articulated, on the arm (9), by pins (15, 16) passing through yokes (17, 18). The movement of the rocker arms (13, 14) is controlled by a receiving cylinder (19) whose two titles (2 (1, 21) push on the ends of the rocker arms (13, 14) according to the arrows (22, 23) which causes pressure of the pins (24, 25) on the jaws (3, 4) and on the braking of the disc (2).

 The oscillation of the arm (9) is determined by a feeler shoe (26) fixed to the end of a latch (27) wedged on the shaft (10).

 Thus it is understood that the oscillation of the latch (27) results in a corresponding oscillation of the arm (9).

However, as the shoe (26) rests on the outer part of the spool of wire or sheet if the angular offset of the latch (27) and the arm (9) are zero, the point of application of the jaws (3, 4) on the disc (2) corresponds substantially to the place of ope the son or the sheet comes off the reel, during the unwinding.

 I1 is provided with an adjustment device between the jack (11) and the articulation (12) constituted by a threaded rod (28) and a nut (29) and lock nut (30) system.

Claims (7)

 3. New device for regulating the tension of a continuous wire or sheet during the unwinding of a reel, the regulation being obtained by continuous braking of the rotation of the reel obtained by jaws (3, 4) tightening a disc (2) whose axis (1) is integral in rotation with said coil, characterized in that provision is made for a radial displacement of the jaws (3, 4) on the disc (2), the mean point of application of the clamping of said jaws (3, 4) on the disc (2) being kept at a distance from the axis (1; proportional to the outside radius of the spool during unwinding.  2. Device as defined in claim 1, characterized in that the jaws (3, 4) are held at the end of a forked arm (9) articulated around an axis (10) parallel to that of the coil and the oscillation of which is controlled by a jack (11) slaved to a command taking account of the diameter of the coil.  3. Device as defined in claim 2, characterized in that the jaws (3, 4) are actuated at the end of rocker arms (13, 14) articulated on each of the teeth (7, 8) of the fork and actuated by a receiving cylinder (19).  4. Device, as defined in claim 2, c a r a c t e r i ed by the fact (, ue I'asservisset.ent movement of the arm (9) is made from mechanical probes (26).  5. Device as defined in claim 2, c a r a c t é r i sé in that the control of the movement of the arm (9) is made from radiation detectors.  6. Device as defined in claim 2, c a r a c t e r i ed by feit that the control of the movement of the arm (9) is made from pneumatic detectors.  7. Device as defined in claim 2, c 8 r a c t é r i sé in that the control of the movement of the arm (9) is made from mechanical detectors.