GB2091002A - Annealing metal wires - Google Patents
Annealing metal wires Download PDFInfo
- Publication number
- GB2091002A GB2091002A GB8100514A GB8100514A GB2091002A GB 2091002 A GB2091002 A GB 2091002A GB 8100514 A GB8100514 A GB 8100514A GB 8100514 A GB8100514 A GB 8100514A GB 2091002 A GB2091002 A GB 2091002A
- Authority
- GB
- United Kingdom
- Prior art keywords
- wire
- annealer
- voltage
- resistance value
- error signal
- 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.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D23/00—Control of temperature
- G05D23/19—Control of temperature characterised by the use of electric means
- G05D23/20—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature
- G05D23/24—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature the sensing element having a resistance varying with temperature, e.g. a thermistor
- G05D23/2401—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature the sensing element having a resistance varying with temperature, e.g. a thermistor using a heating element as a sensing element
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D11/00—Process control or regulation for heat treatments
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
- C21D9/54—Furnaces for treating strips or wire
- C21D9/56—Continuous furnaces for strip or wire
- C21D9/62—Continuous furnaces for strip or wire with direct resistance heating
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Automation & Control Theory (AREA)
- Heat Treatment Of Strip Materials And Filament Materials (AREA)
Abstract
In a continuous annealer the wire (1) passes over a pulley (3) to which is applied a voltage V and over a pulley (4) earthed via a fixed resistor (6). The resultant current in the wire heats it to the annealing temperature. A second fixed resistor (8) is in series with a variable resistor (7) set to produce a reference voltage. If the voltage drop across the two fixed resistors differs, an error signal is developed by a circuit connected to terminals (9 and 10) and used to change the level of power supplied to the annealer and thus stabilize the temperature of the wire. <IMAGE>
Description
SPECIFICATION
Annealing metal wires
This invention relates to apparatus for annealing metal wires and, in particular to continuous annealers which function by passing an electric current through a section of the wire whilst it is moving, thus causing the wire temperature to rise to a point where annealing takes place. By virtue of the fact that the wire is moving, each part of the wire will be raised to the annealing temperature and a continuous output of annealed wire will result.
Most wire materials used on this type of annealer have increasing electrical resistance with increasing temperature and as the degree of anneal imparted to a wire is a function of temperature it follows that, for specific instances, the resistance of the portion of the wire which is being heated will be an accurate indication of the degree of anneal being imparted to the wire.
According to the invention in its broadest aspect, there is provided a method of controlling a continuous annealer for metal wire in which the resistance value of the wire at a predetermined point is measured as a representation of wire temperature by obtaining a ratio between the current value through the wire and an associated voltage drop, this resistance value is compared with a fixed resistance value and any difference between them is applied as an error signal to change the level of power supplied to the annealer.
Preferably, the voltage is measured across a section of wire by contacts which do not carry the annealing current.
According to a further aspect of the invention there is provided apparatus for controlling a continuous annealer for metal wire comprising means for measuring the resistance value of the wire at a predetermined point as a representation of wire temperature, means for comparing this value with a fixed resistance value, means for deriving an error signal from such comparison and means for using the error signal to change the level of power supplied to the annealer.
An embodiment of the invention will now be described by way of example with reference to the accompanying drawings of which: Fig. 1 is a general diagram of the annealer, and
Fig. 2 is a schematic diagram of the annealer control circuit.
Referring firstly to Fig. 1 , the wire 1, moving in the direction of the arrowheads, passes from an earthed contact wheel 2 to a power supply contact wheel 3 then, by way of two insulated pulleys 5, to a second earthed contact wheel 4.
The insulated pulleys 5 enable the length of wire between contact wheels 3 and 4 to be greater than that between contact wheels 2 and 3. This has the effect of producing the greatest temperature rise between wheels 2 and 3 and aids the annealing. As the temperature change between wheels 3 and 4 is smaller and the exit point is from wheel 4, it is convenient to measure the current passing to earth via wheel 4 as this gives greater sensitivity.
The aforementioned current passes through a meter shunt 6 and thus generates a small voltage.
A fixed resistor 8 is chosen in value to produce the same voltage as that generated across the shunt 6 when a variable resistor 7 is set to a value proportionate to the supply voltage fed to wheel 3.
Thus when the wire resistance between wheels 3 and 4 corresponds to the resistance setting of the control variable resistance 7, there is no potential difference between terminals 9 and 10 and if the wire resistance is different from the preset value an error signal appears between terminals 9 and
10 which can be used to change the applied voltage to reduce the error signal. This can be done by conventional servo control means but a preferred circuit arrangement is shown in Fig. 2 and will now be described.
The circuit shown in Fig. 2 provides a thyristor firing angle control voltage of O to 5V which is regulated by the miss-match between the actual resistance of the wire in the second annealer leg and the fixed resistor 8. A low actual resistance increases the thyristor firing angle.
Current is measured by the shunt 6 in the earth lead to the second earth contact wheel 4. This gives a control voltage of 2.5V for 50A.
The balancing voltage is derived from the annealer supply via resistors 7 and 8. The ratio of these is such that the required resistance can be set direct, the full range representing 2 ohms.
These two voltages are compared differentially in an operational amplifier 11 which has a gain of 1 00x and is damped to a period of 1 second by a capacitor 12. Zener Diodes 13, 14 and 15 prevent the application of excess voltages.
A variable resistor 1 6 and a diode 1 7 permit the setting of a minimum firing angle, i.e. minimum voltage, because with no supply connected, the circuit will produce no output.
The circuit functions as follows:- When the supply is connected, the minimum firing angle setting causes a low, fixed voltage to be applied to the annealer.
The shunt 6 measures the current delivering a voltage to terminal 18 of amplifier 11 and a proportion of the supply voltage is supplied to terminal 19 of the amplifier.
For the amplifier to produce an output, terminal 18 must be more positive than terminal 1 9. This corresponds to the actual wire resistance being less than the set resistance.
When this occurs, the amplifier advances the thyristor firing angle, thus heating the wire and raising its resistance.
The circuit stabilises when the resistance reaches the set value.
The current and voltage signals are directly obtained and compared on an instantaneous basis and and only the error is averaged by a capacitor 20.
The control will therefor not be affected by changes in wave form.
The ranges:- 0 to 50 Amps
O to 2 Ohms will cover 0.5 mm aluminium and 0.5 and 0.4 mm copper for speeds of up to 1,800 metres per minute.
It will be noted that, in accordance with the invention, control of the annealing is effected independently of speed.
In a further embodiment, the voltage input is derived by measuring the voltage drop between the pulleys 5. As no current is fed to the wire via these pulleys, any changes in contact resistance will have a minimal effect on the accuracy of the measured voltage.
Claims (5)
1. A method of controlling a continuous annealer for metal wire in which the resistance value of the wire at a predetermined point is measured as a representation of wire temperature by obtaining a ratio between the current value through the wire and an associated voltage drop, this resistance value is compared with a fixed resistance value and any difference between them is applied as an error signal to change the level of power supplied to the annealer.
2. A method as claimed in claim 1 in which the voltage is measured across a section of wire by contacts which do not carry the annealing current.
3. Apparatus for controlling a continuous annealer for metal wire comprising means for measuring the resistance value of the wire at a predetermined point as a representation of wire temperature, means for comparing this value with a fixed resistance value, means for deriving an error signal from such comparison and means for using the error signal to change the level of power supplied to the annealer.
4. A method of controlling a continuous annealer substantially as described with reference to the accompanying drawings.
5. Apparatus for controlling a continuous annealer substantially as described with reference to the accompanying drawings.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8100514A GB2091002A (en) | 1981-01-08 | 1981-01-08 | Annealing metal wires |
AU78635/81A AU7863581A (en) | 1981-01-08 | 1981-12-18 | Annealing metal wires |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8100514A GB2091002A (en) | 1981-01-08 | 1981-01-08 | Annealing metal wires |
Publications (1)
Publication Number | Publication Date |
---|---|
GB2091002A true GB2091002A (en) | 1982-07-21 |
Family
ID=10518863
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB8100514A Withdrawn GB2091002A (en) | 1981-01-08 | 1981-01-08 | Annealing metal wires |
Country Status (2)
Country | Link |
---|---|
AU (1) | AU7863581A (en) |
GB (1) | GB2091002A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5868994A (en) * | 1996-06-06 | 1999-02-09 | Ethicon, Inc. | Constant current needle annealing |
-
1981
- 1981-01-08 GB GB8100514A patent/GB2091002A/en not_active Withdrawn
- 1981-12-18 AU AU78635/81A patent/AU7863581A/en not_active Abandoned
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5868994A (en) * | 1996-06-06 | 1999-02-09 | Ethicon, Inc. | Constant current needle annealing |
US5968394A (en) * | 1996-06-06 | 1999-10-19 | Ethicon, Inc. | Constant current needle annealing |
Also Published As
Publication number | Publication date |
---|---|
AU7863581A (en) | 1982-07-15 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |