GB1603543A - Device for controlling the tension of a wire in a wire delvering machine - Google Patents

Description

(54) DEVICE FOR CONTROLLING THE TENSION OF A WIRE IN A WIRE DELIVERING MACHINE (71) We, VIDEON S.A., a French Company, of 5 bis Rue Mahias, 92100 Boulogne Billancourt, France, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a device for controlling the tension of a wire in a wire delivering machine, such as those used for electrical coil manufacturing.

Such a device is particularly useful as embodied when the wire tension is modified very quickly, and when it is necessary to draw back the wire if it slackens. These requirements are observed when the wire is wound on a non-cylindrical or special shaped coil former with a substantially high production speed. Numerous arrangements have been described in the prior art. A known device employs a free roller storing some wire as described in the French Patent No. 2,211,933; an improved device employs an air jet generated by a source located in front of the wire, as described in the French Patent No. 2,206,752.

However, neither of the above-described prior art approaches eliminate all the slackness when the wire delivering speed is high, due to the very quick change in acceleration of the wire in production. The free roller is sometimes ejected, and the air jet is ineffec tive because of the very small surface area of the wire. Another approach described in the French Patent No. 2,306,026 is to secure a brush around the reel, with its bristles radially located to be swept by the delivered wire, in order to generate a wire tension during wire delivery. Such devices lightly control the wire tension, but can never actually retract the wire as it slackens when the instantaneous linear speed of the wire is suddenly stopped.

An improved method for retraction of the wire has been described in the French Patent No. 2,169,461. In accordance with this inven- tion, the delivered wire passes through two rollers rotated by- an electrical motor in the reverse direction of the one resulting from the normal motion of the delivered wire.

Although this last solution is effective, a disadvantage results from the friction of the wire between the two rollers, i.e. the wire starts burning, which is prejudicial when it is an enamelled-copper wire, and when the coil must be baked after winding to secure its form.

In view of the foregoing, it is an object of this invention to provide an improved device for controlling the tension of a wire in a wire delivering machine and for retracting the wire when it slackens.

The present invention provides a device for incorporation in an electrical coil winding machine in order to control the delivery of wire to be wound into a coil, said device comprising a drum which is freely rotatable about its axis in response to the delivery of said wire, and means for applying a force to said drum in such a manner that the drum presents a variable resistance to rotation in response to wire delivery, in order to control the tension of delivered wire, and that the drum is also subject to a restoring force such that upon the occurrence of slackness in the delivered wire the drum is rotated in a reverse direction to retract surplus wire.

The invention is illustrated by way of example in the accompanying drawings, in which: Figure 1 is a diagrammatic perspective view of one embodiment of the device according to the invention, and Figure 2 is a diagrammatic sectional view showing a second embodiment of the device according to the invention.

It is known that in wire delivering machines the linear acceleration and speed of the delivered wire are functions of the instantaneous use of the wire during manufacturing, particularly if the wire is to be wound on a coil former which is noncylindrical or of special shape, such as used for winding saddle shaped coils for deflecting the beam of a cathode ray tube in a TV set.

When the speed is suddenly reduced, the wire slackens, and it is necessary that the device retracts the excess of delivered wire to retighten it, in order to avoid any displacement of the wire out of the grooves and any breakage consequent upon a renewed high linear acceleration.

The device must therefore comprise means to generate a variable force equivalent to a frictional force to be overcome by the force required to draw off the wire, in order to control the wire tension, and means to generate a force equivalent to a restoring force to retract the wire and to retighten it, when it slackens.

These two forces are generated by the motion of a component out of or back to its stable location. As illustrated in Figure 1, which is a diagrammatic perspective view of one embodiment of the device according to the invention, a drum 1 is normally rotated around the axis XX' by the delivered wire.

Gear wheels or a belt and side groove as illustrated by reference 2, may be used to rotate the drum. A slope 3 is provided on one of the planar areas of the drum 1. A wheel 4, the axis of which is movable in a direction parallel to the axis of the drum 1 against resilient biasing means rolls on this planar area at a point spaced from the drum axis XX'. When the drum is rotating, the wheel 4 climbs upon the slope 3. By this arrangement, when the normal drum rotation is stopped with the wheel on the slope, the return force generated by the resilient biasing means may be resolved into a vertical force and a horizontal force, which makes the drum rotate in reverse direction. Thus by providing a plurality of such slopes on one of the planar areas of the drum, each slope having an upgrade to be climbed by the wheel on normal rotation of the drum and a down-grade substantially perpendicular to the planar area the wheel generates a return force by climbing a slope, this return force being reduced to zero if the wheel passes over the top of the slope, or serving to rotate the drum in the reverse direction if the drum is stopped during the climbing of the wheel.

This results in angular locations of the drum which are not stable.

Moreover, by providing a plurality of such wheels, the return forces are added and may control the rotational speed of the drum in any angular location, and a maximum rotation angle may be defined. With this arrangement, when the delivered wire rotates the drum normally, a force equivalent to a frictional force is generated, which controls the tension of the wire, and when this wire slackens, the drum is rotated in the reverse direction through a determined angle and returned to a stable location, thus retracting excess wire delivered.

However, a drum as described above cannot rotate in a reverse direction through more than a relatively small angle less than 360 .

A second preferred embodiment overcomes this last disadvantage and will be described with reference to Figure 2. The device shown in Figure 2 comprises two parts: the first one is a drum 5, which is rotatable around the axis XX'. For instance, a belt and side groove may be used to rotate the drum 5.

A fine gauge wire mesh 6 is secured on one of the planar areas of the drum and rotates together therewith.

The second part of the device comprises a brush 7, made for instance of a set of flexible bristles located substantially parallel to the axis of the device. The brush is secured onto a support 8 and is located in front of the mesh 6.

The brush support has a threaded hole 9 which engages with a screw threaded part 10 of the shaft supporting the drum 5. The drum is freely rotatable on this shaft, and is mounted for example via roller bearings.

When the support 8 of the brush 7 is rotated around the axis XX', the space e between the drum 5 and the support 8 is modified by way of the threaded part 10, cooperating with the threaded hole 9. When this space eis less than the length of the flexible bristles of the brush 6, these bristles penetrate into the holes of the wire mesh and bristle torsion results from a rotation of the mesh, the bristles returning to their initial form when they are opposite the holes in the mesh. The bristle torsion gener ates a force which is a function of the length of the bristles introduced into the holes of the mesh, and thus a function of the space e between the drum 5 and the support 8, and additionally a function of the number of flexible bristles of the brush, and of the gauge of the mesh. This generated force is equiva lent to a frictional force opposing the motion of the drum 5 around the axis XX' and thus acting on the delivered wire.

Control of the variable force is achieved by determining the space e between the drum 5 and the brush support 8 by moving the support 8 around-the axis of the shaft. Hence, the device may be self-controlled if the brush support 8 has a stable angular location which is modified by the rotation of the drum itself, by using, for instance a spring, one end of which is secured to the device frame and the other end of which is secured to the brush support 8 in spaced relationship to the axis XX'. Accordingly, any angular motion of the brush support 8 generates a return force in the spring which tries then, to restore the brush support into its stable angular location.

When the drum is normally rotating, the force generated by the flexible bristles in torsion drives the brush support in the same direction as the drum, which increases the space e between drum and brush support 8, and so thus decreases the force upon the bristles. Simultaneously, the return force generated in the spring increases in opposition to the rotation of the brush support. The device thus peaches a position of equilibrium.

Any change in angular speed of the drum modifies this equilibrium of the forces: if this speed increases, for example, the bristle torsion force applied to the mesh increases also; the brush support moves in the same direction as the mesh and the space e is increased, which decreases the return force stored in the spring; a new equilibrium is thus achieved.

Likewise, if the drum angular speed decreases, the bristle torsion force applied to the mesh decreases too, and the return force stored in the spring moves the brush support in the reverse direction which decreases the space e between drum and the brush support, so that the force opposed to the rotation of the mesh increases; a new equilibrium is then achieved.

If the drum stops, the bristle torsion force is reduced to zero and the return force stored in the spring moves the brush support in the reverse direction to that of the normal direction of rotation. The space e is then at a minimum, so that drum and brush support are secured together. This return force then moves the drum and bush support as a unit in the same reverse direction to achieve a new equilibrium, which results in a retraction of the excess of delivered wire.

Although the invention has been described in relation to specific embodiments, it will be appreciated that modifications and changes may be made by those skilled in the art without departing from the scope of the invention as defined in the appended claims.

For example, the return force achieved by the spring in both described embodiments may be achieved by any other means, i.e. gas, fluid, or computer aided motor. The number of the slopes in the first described embodiment depends on the required result; the choice of the means used for normally rotating the drum with the delivered wire is immaterial.

WHAT WE CLAIM IS: 1. A device for incorporation in an electrical coil winding machine in order to control the delivery of wire to be wound into a coil, said device comprising a drum which is freely rotatable about its axis in response to the delivery of said wire, and means for applying a force to said drum in such a manner that the drum presents a variable resistance to rotation in response to wire delivery, in order to control the tension of delivered wire, and that the drum is also subject to a restoring force such that upon the occurrence of slackness in the delivered wire the drum is rotated in a reverse direction to retract surplus wire.

2. A device as claimed in Claim 1 comprising a plurality of slopes provided on an end face of the said drum, each slope having a slow up grade in the direction of the rotation with wire delivery, and a down grade substantially perpendicular to the end face of the drum, and wherein the said force applying means comprises at least one wheel, the axis of which is movable away from said end face of the drum against resilient biasing means and which is arranged adjacent said end face in spaced relationship with the said drum axis, in order to engage the said slopes.

3. A device as claimed in Claim 2, wherein the said resilient biasing means is a compression spring.

4. A device as claimed in Claim 2, wherein the said resilient biasing means is a pump ram acting in a fluid or in a gas.

5. A device as claimed in Claim 1 comprising a wire mesh secured to one of the end faces of the said drum, a brush secured on a support located on the same axis as said drum and arranged axially adjacent said mesh, said support being screw threaded on a shaft with respect to which said drum is axially fixed so that rotation of the brush support on said shaft varies the axial spacing between the support and the drum, and wherein the said force applying means comprises means for applying a restoring force to the brush support in order to rotate it in a direction such as to reduce the spacing between the support and the drum.

6. A device as claimed in Claim 5, in which the said means for applying a restoring force comprises a spring, one end of which is secured to the device frame and the other end of which is secured to the brush support in spaced relationship with its rotary axis.

7. A device as claimed in Claim 5, in which the said means for applying a restoring force is a computer aided motor controlling the said space between the brush support and the drum.

8. A device for controlling the tension of a wire in a wire delivering machine, substantially as described herein with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. the spring which tries then, to restore the brush support into its stable angular location. When the drum is normally rotating, the force generated by the flexible bristles in torsion drives the brush support in the same direction as the drum, which increases the space e between drum and brush support 8, and so thus decreases the force upon the bristles. Simultaneously, the return force generated in the spring increases in opposition to the rotation of the brush support. The device thus peaches a position of equilibrium. Any change in angular speed of the drum modifies this equilibrium of the forces: if this speed increases, for example, the bristle torsion force applied to the mesh increases also; the brush support moves in the same direction as the mesh and the space e is increased, which decreases the return force stored in the spring; a new equilibrium is thus achieved. Likewise, if the drum angular speed decreases, the bristle torsion force applied to the mesh decreases too, and the return force stored in the spring moves the brush support in the reverse direction which decreases the space e between drum and the brush support, so that the force opposed to the rotation of the mesh increases; a new equilibrium is then achieved. If the drum stops, the bristle torsion force is reduced to zero and the return force stored in the spring moves the brush support in the reverse direction to that of the normal direction of rotation. The space e is then at a minimum, so that drum and brush support are secured together. This return force then moves the drum and bush support as a unit in the same reverse direction to achieve a new equilibrium, which results in a retraction of the excess of delivered wire. Although the invention has been described in relation to specific embodiments, it will be appreciated that modifications and changes may be made by those skilled in the art without departing from the scope of the invention as defined in the appended claims. For example, the return force achieved by the spring in both described embodiments may be achieved by any other means, i.e. gas, fluid, or computer aided motor. The number of the slopes in the first described embodiment depends on the required result; the choice of the means used for normally rotating the drum with the delivered wire is immaterial. WHAT WE CLAIM IS:

1. A device for incorporation in an electrical coil winding machine in order to control the delivery of wire to be wound into a coil, said device comprising a drum which is freely rotatable about its axis in response to the delivery of said wire, and means for applying a force to said drum in such a manner that the drum presents a variable resistance to rotation in response to wire delivery, in order to control the tension of delivered wire, and that the drum is also subject to a restoring force such that upon the occurrence of slackness in the delivered wire the drum is rotated in a reverse direction to retract surplus wire.

2. A device as claimed in Claim 1 comprising a plurality of slopes provided on an end face of the said drum, each slope having a slow up grade in the direction of the rotation with wire delivery, and a down grade substantially perpendicular to the end face of the drum, and wherein the said force applying means comprises at least one wheel, the axis of which is movable away from said end face of the drum against resilient biasing means and which is arranged adjacent said end face in spaced relationship with the said drum axis, in order to engage the said slopes.

3. A device as claimed in Claim 2, wherein the said resilient biasing means is a compression spring.

4. A device as claimed in Claim 2, wherein the said resilient biasing means is a pump ram acting in a fluid or in a gas.

5. A device as claimed in Claim 1 comprising a wire mesh secured to one of the end faces of the said drum, a brush secured on a support located on the same axis as said drum and arranged axially adjacent said mesh, said support being screw threaded on a shaft with respect to which said drum is axially fixed so that rotation of the brush support on said shaft varies the axial spacing between the support and the drum, and wherein the said force applying means comprises means for applying a restoring force to the brush support in order to rotate it in a direction such as to reduce the spacing between the support and the drum.

6. A device as claimed in Claim 5, in which the said means for applying a restoring force comprises a spring, one end of which is secured to the device frame and the other end of which is secured to the brush support in spaced relationship with its rotary axis.

7. A device as claimed in Claim 5, in which the said means for applying a restoring force is a computer aided motor controlling the said space between the brush support and the drum.

8. A device for controlling the tension of a wire in a wire delivering machine, substantially as described herein with reference to the accompanying drawings.