GB2104252A - Controlling tension in flexible material being unwound from a drum - Google Patents
Controlling tension in flexible material being unwound from a drum Download PDFInfo
- Publication number
- GB2104252A GB2104252A GB08217080A GB8217080A GB2104252A GB 2104252 A GB2104252 A GB 2104252A GB 08217080 A GB08217080 A GB 08217080A GB 8217080 A GB8217080 A GB 8217080A GB 2104252 A GB2104252 A GB 2104252A
- Authority
- GB
- United Kingdom
- Prior art keywords
- arm
- tension
- amplifier
- flexible material
- motor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000000463 material Substances 0.000 title claims abstract description 50
- 239000013307 optical fiber Substances 0.000 claims abstract description 19
- 230000002441 reversible effect Effects 0.000 claims abstract description 14
- 238000004804 winding Methods 0.000 claims description 10
- 238000006073 displacement reaction Methods 0.000 claims description 7
- 230000006641 stabilisation Effects 0.000 claims description 3
- 239000000835 fiber Substances 0.000 abstract description 2
- 230000000694 effects Effects 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000013016 damping Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 238000005491 wire drawing Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D15/00—Control of mechanical force or stress; Control of mechanical pressure
- G05D15/01—Control of mechanical force or stress; Control of mechanical pressure characterised by the use of electric means
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
- B65H59/00—Adjusting or controlling tension in filamentary material, e.g. for preventing snarling; Applications of tension indicators
- B65H59/38—Adjusting or controlling tension in filamentary material, e.g. for preventing snarling; Applications of tension indicators by regulating speed of driving mechanism of unwinding, paying-out, forwarding, winding, or depositing devices, e.g. automatically in response to variations in tension
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Automation & Control Theory (AREA)
- Tension Adjustment In Filamentary Materials (AREA)
- Controlling Rewinding, Feeding, Winding, Or Abnormalities Of Webs (AREA)
Abstract
The drum D is driven by a shaft 2 coupled to a reversible electric motor and is mounted on a freely pivotted arm 3 to which a tensioning bias is applied by a spring 6. The angle of the arm is sensed by a transducer 9, 10 connected as a variable input impedance to an amplifier which supplies the armature and/or field current of the motor. A resistance-capacitance circuit also in the input reduces hunting. The external drive for the material exerts a greater pull than that of the motor, whose direction of energisation is determined by whether the tension (i.e. the angle of the arm) is above or below a desired value. The material may be optical fibre. The motor is de-energised by a damped microswitch 12 if the fibre breaks. <IMAGE>
Description
SPECIFICATION
Improvements in apparatus for controlling the tension in a flexible material as it is being wound on to or unwound from a drum
This invention relates to apparatus for controlling the tension in a flexible material as it passes between means for driving the flexible material and a drum on to which the material is being wound or from which it is being unwound. The means for driving the flexible material may be a capstan or similar driving device and may be incorporated in apparatus for processing the flexible material e.g. a wire drawing apparatus, an enamelling machine or apparatus for tubing optical fibre. Alternatively, it may be a drum on to which the flexible material is being wound.The term "drum" is used in this specification in its broadest sense as including not only the cylindrical barrels (of circular cross-section) of spools, reels etc., but also non-cylindrical members and frames, e.g. of rectangular or polygonal cross-section, on which it may be desired to wind flexible materials at constant tension.
The invention is especially but not exclusively applicable to very thin and light flexible materials, for example, very fine wires, optical fibres and thin paper tapes.
Known apparatus for controlling the tension in a flexible material as it passes between means for driving the flexible material and a drum on to which the material is being wound or from which it is being unwound is described in our U.K. Patent Specification No: 918174 and comprises an electric motor driving, either directly or through a gear train, the drum from which or on to which the flexible material is being wound; a multi-stage high gain electronic amplifier for supplying either the armature current or the field current of the motor or both; a sensing device responsive to changes in the tension of the flexible material in its path between the drum and the means for driving the flexible material, which device varies, in accordance with the tension, the value of an impedance controlling the amplifier input; and a resistance/capacitance stabilisation network, designed to inhibit hunting in the system connected in the amplifier input circuit. The arrangement is such that when the impedance is at an optimum value corresponding to the desired tension in the flexible material, the amplifier supplies field or armature current (or both) to drive the motor in an appropriate direction and at a sufficient torque to maintain that tension in the material and when the tension changes, causing the impedance to vary from the optimum value, the armature and/or field current supplied by the amplifier varies in such a way as to restore the tension to the desired value and, if necessary to attain this end, in such a way as to drive the motor in the opposite direction.
Generally the sensing device comprises a jockey pulley acted upon by a loop of the flexible material, in its path between the drum and the means for driving the flexible material, and by a substantially constant biassing force opposing the tension in the flexible material, the sensing device varying, in accordance with the movement of the jockey pulley, the value of the impedance controlling the amplifier input.Whilst a sensing device incorporating a jockey pulley acted upon by a loop of the flexible material is perfectly satisfactory for most applications, we have found that where the flexible material is an optical fibre there is a risk that, in causing the optical fibre travelling between the drum and the means for driving the optical fibre to pass in a loop around a jockey pulley, the optical fibre may be so damaged as to increase to an undesirable extent the attenuation of a signal when transmitted along the fibre.
It is an object of the present invention to provide improved apparatus for controlling the tension in an optical fibre or other flexible material as it passes between means for driving the flexible material and a drum on to which the material is being wound or from which it is being unwound, which apparatus effects negligible deflection of, and consequently substantially reduces risk of damage to, the advancing optical fibre or other flexible material.
The apparatus in accordance with the invention comprises a reversible electric motor driving, either directly or through a gear train, a rotatable shaft; a multi-stage high gain electronic amplifier for supplying substantially the whole of either the armature current or the field current of the motor or both; a sensing device, responsive to changes in tension of the flexible material being wound on to or unwound from the drum, which sensing device comprises an arm freely pivotably mounted between its ends about the axis of the shaft, the drum being rotatably mounted at one end of the arm and being driven, through a flexible drive, by said rotatably driven shaft, means for applying a substantially constant biassing force opposing the tension in the flexible material and, mechanically coupled to the arm, means for varying the value of an impedance controlling the amplifier input in accordance with pivotal movement of the arm; and a resistancecapacitance stabilisation network, designed to inhibit hunting in the system, connected in the amplifier input circuit, the means for driving the flexible material being capable of exerting a greater longitudinal force on the flexible material than is the reversible motor and the supply or take-up drum driven thereby, and the arrangement being such that when the impedance is at an optimum value corresponding to the desired tension in the flexible material, the amplifier supplies field or armature current (or both) to drive the motor in an appropriate direction and at a sufficient torque to maintain that tension in the material and when the tension changes, causing the impedance to vary from the optimum value, the armature and/or field current supplied by the amplifier varies in such a way as to restore the tension to the desired value and, if necessary to attain this end, in such a way as to drive the motor in the opposite direction.
When the amplifier supplies both the field and the armature current of the motor either the field winding or the armature of the motor is connected across a bridge rectifier in series with the armature or field, as the case may be, in such a way that when the amplifier output is reversed the motor will reverse. When the amplifier supplies the armature current only the field current is obtained from a source such that substantially constant current passes through the field windings or alternatively a permanent magnet motor may be used. When the amplifier output supplies the field current only, the armature current is derived from a substantially constant current power supply.
The term "high gain amplifier" means an amplifier having a power output sufficient to provide the whole of the armature or field current to drive the reversible motor and yet having a low current input that can be controlled by a simple displacement transducer, a simple potentiometer or other variable impedance, that is to say, a transducer or potentiometer that can be actuated through the desired range under the action of a very small force exerted on it by the flexible material. The power gain of the amplifier will normally not be less than 103 but is preferably greater than 106.
The means for applying a substantially constant biassing force opposing the tension in the flexible material preferably comprises at least one coil spring which is connected to the arm at one of its ends and which, at the other of its ends, is adjustably fixed to a support to enable the apparatus to be set to maintain the desired tension in the flexible material.
The means for varying the value of the impedance controlling the amplifier input in accordance with pivotal movement of the arm preferably comprises a displacement transformer whose core is secured to one end of a flexible line, the other end of the flexible line being secured to the arm and the arrangement being such that pivotal movement of the arm moves the core of the transformer in one or other longitudinal direction relative to the transformer winding.
Preferably, the apparatus includes a microswitch or other means which is so positioned with respect to the arm that, in the event of breakage of the flexible material, the arm will pivot under the action of the biassing means to such an extent as to actuate the microswitch and switch off the reversible electric motor.
To accommodate drums of large size, the sensing device of the apparatus may comprise two arms, each freely pivotally mounted between its ends about the axis of the shaft, the two arms being longitudinally spaced apart along the shaft axis and being adapted to have a drum rotatably mounted between them at one of their ends.
As in our known apparatus hereinbefore described, the amplifier is preferably a transistor or thyristor amplifier and preferably has two output circuits, one of which supplies current to the motor when the impedance in its input circuit is above a predetermined value and the other of which supplies current to the motor when the impedance is below the optimum value. The predetermined value will vary from the optimum value referred to above by an amount dependent on the tension desired in the flexible material.These two output circuits are preferably connected to separate field windings or separate parts of the same field winding of the motor, and are always connected in such a way that when one circuit is effective the armature will tend to rotate in one direction and when the other circuit is effective the armature will tend to rotate in the opposite direction.For example, when the motor is a split field motor, the two separate output circuits of the amplifier may have a common terminal connected to a common terminal of the field windings and the output between the common terminal of the amplifier and one other terminal is positive with respect to a common terminal when the resistance in the amplifier input circuit is above the predetermined value and the output between the common terminal and the other terminal of the amplifier output negative when the resistance in the amplifier input circuit is below the predetermined value.
Commutation diodes are preferably connected across each output circuit to prevent over voltage caused by inductance in the load circuits.
Alternatively, an amplifier with a bi-directional output from a single pair of output terminals may be used, the amplifier circuit being such that when the resistance in the input circuit is above the predetermined value, the output of the amplifier is positive and when it is below, the output is negative; such an amplifier can be used with an electric motor having a single field winding.
The invention will be further illustrated by a description, by way of example, of the sensing device of apparatus for controlling the tension in optical fibre being unwound from a drum with reference to the accompanying drawing which shows a perspective view of the device.
Referring to the drawing, the apparatus comprises a reversible electric motor (not shown) which is mounted on the rear face of a support 1 and which is directly coupled to a rotatable shaft 2. Freely pivotably mounted on the shaft 2 is an arm 3 at the lower end of which is rotatably mounted a drum D of optical fibre, the drum being rotatably driven by the rotatable shaft 2 through a flexible drive 4. The upper end of the arm 3 carries a counterweight 5. Three coil springs 6, connected in series, are secured at one of their ends to the upper end of the arm 3 and, at the other of their ends, are adjustably secured to a wall 8 of an enclosure 7, the cover plate of which is removed. Also mounted on the support 1 within the enclosure 7 is a displacement transformer 9 whose core 10 is mechanically coupled to the arm 3 via a flexible line 11. The displacement transformer 9 serves to vary the value of an impedance controlling a multi-stage high gain electronic amplifier (not shown) for applying susbstantially the whole of either the armature current or the field current of the reversible motor or both in accordance with pivotal movement of the arm 3. Also mounted on the support 1 adjacent the arm 3 is a hydraulic damping device 12 which provides for smooth operation of a microswitch (not shown) controlling the power supply to the reversible motor, i.e. by substantially eliminating oscillation or "bounce" of the arm.
In operation, the coil springs 6 are set to maintain the desired tension in the optical fibre to be unwound from the drum D and the optical fibre is unwound from the drum by a capstan or similar driving device incorporated in apparatus for proces sing the optical fibre. In the event of an increase in tension in the optical fibre being unwound from the drum D, the arm 3 will be caused to pivot about the axis of the shaft 2 in a clockwise direction against the biassing spring 6 to draw the transformer core 10 from the displacement transformer 9, thereby varying the value of the impedance controlling the amplifier input to such an extent that the reversible motor, and hence the rotatable shaft 2, is driven in such a rotatable direction as to rotate the drum D in a clockwise direction at such a speed as to reduce the tension in the optical fibre. In the event of a decrease in tension in the optical fibre being unwound from the drum D, the arm 3 will pivot about the axis of the shaft 2 in an anti-clockwise direction underthe action of the springs 6 to cause the core 10 of the displacement transformer 9 to move lengthwise with respect to the transformer core in such a direction as to vary the value of the impedance controlling the amplifier input in such a way as to cause the motor and hence the shaft 2, to be driven in an anticlockwise direction to drive the drum D in an anti-clockwise direction and hence increase the tension in the optical fibre.
In the event of a breakage in the optical fibre, the arm 3 will pivot in an anti-clockwise direction under the action of the spring 6 until it engages the damper 12 to effect actuation of the microswitch and disconnection of the power supply to the reversible motor.
Claims (10)
1. Apparatus for controlling the tension in a flexible material as it is being wound on to or unwound from a drum, said apparatus comprising a reversible electric motor driving, either directly or through a gear train, a rotatable shaft; a multi-stage high gain electronic amplifier for supplying substantiallythe whole of either the armature current or the field current of the motor or both; a sensing device,
responsive to changes in tension of the flexible
material being wound on to or unwound from the drum, which sensing device comprises an arm freely pivotably mounted between its ends about the axis of the shaft, the drum being rotatably mounted at one end of the arm and being driven, through flexible drive, by said rotatably driven shaft; means for applying a substantially constant biasing force
opposing the tension in the flexible material and;
mechanically coupled to the arm, means for varying the value of an impedance controlling the amplifier
input in accordance with pivotal movement of the arm; and a resistance-capacitance stabilisation network, designed to inhibit hunting in the system, connected in the amplifier input circuit, the means for driving the flexible material being capable of
exerting a greater longitudinal force on the flexible
material than is the reversible motor and the supply
or take up drum driven thereby, and the arrange
ment being such that when the impedance is at an
optimum value corresponding to the desired tension
in the flexible material, the am piifier supplies field
and/or armature current two drive the motor in an
appropriate direction and at a sufficient torque to
maintain that tension in the material and when the tension changes, causing the impedance to vary from the optimum value, the armature and/or field current supplied by the amplifier varies in such a way as to restore the tension to the desired value and, if necessary to attain this end, in such a way as to drive the motor in the opposite direction.
2. Apparatus as claimed in Claim 1, wherein the means for applying a substantially constant biasing force opposing the tension in the flexible material comprises at least one coil spring which is connected to the arm at one of its ends and which, at the other of its ends, is adjustably fixed to a support to enable the apparatus to be set to maintain the desired tension in the flexible material.
3. Apparatus as claimed in Claim 1 or Claim 2, wherein the means for varying the value of the impedance controlling the amplifier imput in accordance with pivotal movement of the arm comprises a displacement transformer whose core is secured to one end of a flexible line, the other end of the flexible line being secured to the arm and the arrangement being such that pivotal movement of the arm moves the core of the transformer in one or other longitudinal direction relative to the transformer winding.
4. Apparatus as claimed in any one of the preceding Claims, wherein the apparatus includes a microswitch or other means which is so positioned with respect to the arm that, in the event of breakage of the flexible material, the arm will pivot under the action of the biasing means to such an extent as to actuate the microswitch and switch off the reversible electric motor.
5. Apparatus as claimed in any one of the preceding Claims, wherein the sensing device comprises two arms, each freely pivotally mounted between its ends about the axis of the shaft, the two arms being longitudinally spaced apart along the shaft axis and being adapted to have a drum rotatably mounted between them at one of their ends.
6. Apparatus as claimed in any one of the preceding Claims, wherein the amplifier is a transistor or thyristor amplifier and has two output circuits, one of which supplies current to the motor when the impedance in its imput circuit is above a predetermined value and the other of which supplies current to the motor when the impedance is below the optimum value.
7. Apparatus as claimed in Claim 6, wherein the two output circuits are connected to separate field windings or separate parts of the same field winding of the motor, and are always connected in such a way that when one circuit is effective the armature will tend to rotate in one direction and when the
other circuit is effective the armature will tend to
rotate in the opposite direction.
8. Apparatus as claimed in Claim 6 or Claim 7, wherein commutation diodes are connected across
each output circuit to prevent over voltage caused by
inductance in the load circuits.
9. Apparatus as claimed in any one of Claims 1 to
5, wherein the amplifier has a bi-directional output from a single pair of output terminals, the amplifier
circuit being such that when the resistance in the
imput circuit is above a predetermined value, the output of the amplifier is positive and when the resistance is below the predetermined value the output is negative.
10. Apparatus for controlling the tension in optical fibre as it is being unwound from a drum substantially as hereinbefore described with reference to, and as shown in, the accompanying drawing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08217080A GB2104252B (en) | 1981-06-12 | 1982-06-11 | Controlling tension in flexible material being unwound from a drum |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8118053 | 1981-06-12 | ||
| GB08217080A GB2104252B (en) | 1981-06-12 | 1982-06-11 | Controlling tension in flexible material being unwound from a drum |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2104252A true GB2104252A (en) | 1983-03-02 |
| GB2104252B GB2104252B (en) | 1984-11-07 |
Family
ID=26279766
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08217080A Expired GB2104252B (en) | 1981-06-12 | 1982-06-11 | Controlling tension in flexible material being unwound from a drum |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2104252B (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2571034A1 (en) * | 1984-09-28 | 1986-04-04 | Pourtier Pere Fils Ets | Tension-control apparatus for unwinding a fragile fibre or thread (wire) from a reel or winding such a thread (wire) onto a reel |
| GB2166602A (en) * | 1984-09-21 | 1986-05-08 | Australian Telecomm | Cable laying apparatus |
| WO1989011155A1 (en) * | 1988-05-07 | 1989-11-16 | Robert Bosch Gmbh | Process and device for producing coils of resistance wire having a predetermined electrical resistance |
| GB2240409A (en) * | 1989-11-15 | 1991-07-31 | John Burdon | Automatic adjustment of tension in material drawn off a roll. |
| WO1995020538A1 (en) * | 1994-01-28 | 1995-08-03 | Ppg Industries, Inc. | Method and apparatus for reducing catenary during winding of a fiber bundle |
| WO2014039005A1 (en) * | 2012-09-04 | 2014-03-13 | Venture Corporation Limited | An apparatus and method for maintaining consistent tension of a flexible flat cable undergoing extension or retraction |
| CN115258823A (en) * | 2022-05-19 | 2022-11-01 | 西安航空学院 | An optical fiber winding machine tension adjustment structure and method |
-
1982
- 1982-06-11 GB GB08217080A patent/GB2104252B/en not_active Expired
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2166602A (en) * | 1984-09-21 | 1986-05-08 | Australian Telecomm | Cable laying apparatus |
| FR2571034A1 (en) * | 1984-09-28 | 1986-04-04 | Pourtier Pere Fils Ets | Tension-control apparatus for unwinding a fragile fibre or thread (wire) from a reel or winding such a thread (wire) onto a reel |
| WO1989011155A1 (en) * | 1988-05-07 | 1989-11-16 | Robert Bosch Gmbh | Process and device for producing coils of resistance wire having a predetermined electrical resistance |
| US5090112A (en) * | 1988-05-07 | 1992-02-25 | Robert Bosch Gmbh | Method and apparatus for manufacturing coils |
| GB2240409A (en) * | 1989-11-15 | 1991-07-31 | John Burdon | Automatic adjustment of tension in material drawn off a roll. |
| GB2240409B (en) * | 1989-11-15 | 1994-02-02 | John Burdon | The automatic adjustment of tension in material drawn off a roll |
| WO1995020538A1 (en) * | 1994-01-28 | 1995-08-03 | Ppg Industries, Inc. | Method and apparatus for reducing catenary during winding of a fiber bundle |
| WO2014039005A1 (en) * | 2012-09-04 | 2014-03-13 | Venture Corporation Limited | An apparatus and method for maintaining consistent tension of a flexible flat cable undergoing extension or retraction |
| CN115258823A (en) * | 2022-05-19 | 2022-11-01 | 西安航空学院 | An optical fiber winding machine tension adjustment structure and method |
| CN115258823B (en) * | 2022-05-19 | 2023-08-22 | 西安航空学院 | Tension adjustment structure and method of an optical fiber winding machine |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2104252B (en) | 1984-11-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |