GB2227256A

GB2227256A - Tensionning wire

Info

Publication number: GB2227256A
Application number: GB8828854A
Authority: GB
Inventors: Alexander James Ciniglio; Neil Christopher Squire
Original assignee: Evenoak Ltd
Current assignee: Evenoak Ltd
Priority date: 1988-12-09
Filing date: 1988-12-09
Publication date: 1990-07-25
Also published as: GB8828854D0

Abstract

A tensioner has two light weight pulleys 10 and 11 which are mounted with their tyred peripheries abutting together to form a nip for a wire 12 extending in use through the tensioner. An arm 13, having a wire guide 14, is normally fixed but pivotably mounted about a point 15. A strain gauge 16 is mounted on the arm 13. The drag exerted on the wire by the pulleys 10 and 11 is altered according to the strain, monitored by the strain gauge, on the arm 13. <IMAGE>

Description

WIRE TENSIONER This invention relates to wire tensioners.

This invention relates more particular to wire (or thread) tensioners for use with fire guage wire such as used for electrical coil windings and requiring to be passed through skeining devices. Tensioners are already known which are arranged to respond automatically to changes in tension and to maintain the tension within a desired range. One such arrangement includes a spring biassed arm with a guide for the wire in which the arm moves when the tension changes. The position of the arm is sensed to control the drag on an associated pulley around which the wire is wrapped. In such an arrangement especially for low tension the response time of the tension is fairly long and the sensitivity low, the wire is difficult to thread, and no provision can be made for removing the tension altogether.

According to the invention there is provided a wire tensioner comprising a pair of side by side light weight pulleys with their peripheries engaged to provide a nip for the wire passing through the tensioner, a fixed arm having a wire guide which off-set from the natural path of the wire, and means for responding to the strain on the arm caused by the wire and for controlling the rotational drag of at least one of the pulleys so as to maintain the tension in the wire within a desired range.

Preferably the pulleys are additionally mechanically coupled together so as to rotate at the same speed.

The strain on the arm is preferably sensed by monitoring a strain gauge mounted on the arm.

The pulleys are preferably arranged to be selectively movable to separate their peripheries from one another enabling the wire to pass through the tensioner without touching the pulleys such that the tensioner applies very little or no tension at all to the wire.

The fixed arm may be pivotably mounted to enable the arm to swing away from the natural path of the wire to fascilitate threading of the wire into the tensioner.

Tensioners according to the invention will now be described by way of example with reference to the accompanying schematic drawings in which: Fig 1 is a plan view of one tensioner; Fig 2 is a side view of the one tensioner; Fig 3 is an end view; and Fig 4 is a plan view of another tensioner.

Referring to the drawings, the tensioner has two light weight pulleys 10 and 11 are mounted with their tyred peripheries abutting together to form a nip for a wire 12 extending in use through the tensioner. An arm 13, having a wire guide 14, is normally fixed but pivotably mounted about a point 15. A strain gauge 16 is mounted on the arm 13. Non-movable guides 17 and 18 are positioned at either side of the guide 14.

In figure 3, the shafts 19 and 20 of the pulleys 10 and 11 extend to further pulleys 21 (only one is shown) mechanically connected together by a belt 22. The rotor 23 of an electric motor 24 has a screw mounted thereon which drives a friction disc 25 towards and away from the underside of the pulley 10. The pressure applied by the disc causes a drag on the pulley 10 which is increased as the disc 25 is pressed more firmly against the underside of the pulley 10. The motor 24 is controlled in accordance with signals generated by the strain gauge 16.

In use, the wire 12 is fed through the tensioner and urges the arm 13 upwards, as seen in Figure 1, out of the normal path of the wire.

Depending on the upward force applied by wire, the strain in the arm varies and the strain gauge responds to the variations to cause the motor 24 to alter the effective drag of the pulleys 10 and 11 on the wire 12 and hence the tension of the wire. The tensioner can thus be set up to maintain the wire tension automatically within a desired range.

Should it be necessary, as it often is especially when skeining is to be carried out, to reduce the wire tension to zero or near zero, the peripheries of the pulleys 10 and 11 are separated to allow the wire 12 to pass through the tensioner without contacting the pulleys 10 and 11 at all.

For threading the wire 12, not only can the pulleys be separated but a pivoted lever 26 is provided. Operation of the lever 26, causes the arm 13 to pivot upwards, as seen in Figure 1, so that the wire 12 can be simply placed in line between the peripheries of the pulley 10 and 11 and the fixed guides 17 and 18.

It will be noted that because the wire 12 passes between two pulleys any lateral protrusions on the wire tend to be compressed towards the longitudinal axis of the wire. This is especially advantage as compared to earlier tensioners where skeining has taken place. Any ears for example formed during skeining tend to be pressed down in the described tensioner and the wire then passes more easily over or through any other fixed guides on its onward passage to an associated coil winding machine.

In Fig 4, a light weight pulley 26, which is controlled to exert a drag on the wire 12 as described above, has its periphery in contact with the peripheries of two pulleys 27. The pulleys 27 are mounted on a U-shaped arm 28 which can move towards and away from the pulley 26. The wire engages between the nips formed by the pulley 26 and the pulleys 27 and extends around a peripheral arc of about 900 of the pulley 26. When the arm is moved away from the pulley 26, the wire 12 is easily threaded into the tensioner.

It will be noted with both the tensioners described the pulleys, although an extra idler pulley may have to be added to the embodiment of Fig 4, that the drag may be applied at a point significantly separated from the sensing of strain generated by the wire 12. For example, the strain gauge arrangement may be situated at one end of a skeining apparatus and the tension adjusted by pulleys 10 and 11, say, situated at the other end of the skeining apparatus.

Claims

CLAIMS:-

1. A wire tensioner comprising a pair of side by side -light weight pulleys with their peripheries engaged to provide a nip for the wire passing through the tensioner, a fixed arm having a wire guide which is off-set from the natural path of the wire, and means for responding to the strain on the arm caused by the wire and for controlling the rotational drag of at least one of the pulleys so as to maintain the tension in the wire within a desired range.

2. A wire tensioner according to Claim 1 in which the pulleys are additionally mechanically coupled together so as to rotate at the same speed.

3. A wire tensioner according to Claim 1 or 2 including a strain gauge mounted on the arm and the means for responding to the strain on the arm is arranged to monitor the strain gauge.

4. A tensioner according to any one of Claims 1 to 3, in which the pulleys are arranged to be selectively movable to separate their peripheries from one another enabling the wire to pass through the tensioner without touching the pulleys such that the tensioner applies very little or no tension at all to the wire.

5. A tensioner according to any one of Claims 1 to 4 in which fixed arm is pivotably mounted to enable the arm to swing away from the natural path of the wire to fascilitate threading of the wire into the tensioner.

6. Tensioner substantially as herein described with reference to any one or more of Figs. 1 to 4 of the accompanying drawings.