JPS6235207B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for carrying out a method for adjusting metal wire coating equipment.

Coated equipment is particularly used for insulated conductors used in telephone equipment or general electrical equipment. The demand for the above-mentioned conductors is steadily increasing year by year, and the need for high-output, high-production equipment is therefore increasing. The equipment consists of an extruder with a head designed to continuously press a layer of molten plastic material onto the metal wire through which it passes. The thus coated wire then passes through a movable trough where it is sprayed with one or more water jets. Once cooled, the wire enters a winding machine and is wound onto a drum.

In order to increase the production capacity of this type of equipment,
It is desired to increase the speed of the metal wire passing through the extrusion head, and conductors with diameters a few tenths of a millimeter have now been realized at speeds of over 2000 m/min. However, insulated telephone wire production must meet strict specifications regarding coating properties, expressed in terms of wire capacitance per meter of travel, which must be within very narrow limits. If the insulation coating consists of an expanded polymer,
The capacitance of a conductor is determined by the coefficient of expansion of the material and then by its temperature.

Regulating devices are known which sense this temperature and operate at a switch which controls a heating element housed in the extruder cylinder in order to keep it constant. Although various attempts have been made to improve upon these known devices, their main drawback is their inertia, which measures the capacity of the wire after jacket cooling rather than by measuring the temperature within the extrusion head. It was hot. Capacitance measuring devices are known which operate continuously and compare measured values with predetermined gauge values. These devices provide an error signal giving the measured value deviation from the gauge value in amplitude and sign. This signal is used to control the heating of the cylinder or, in some cases, the running speed of the line.

However, all the above-mentioned known methods are insufficient due to their inertia and lack of accuracy when it is desired to operate at maximum linear speeds as mentioned above. The object of the present invention is to provide a method and a device that allow high-speed production of coated wires that meet the requirements imposed on the capacitance per meter of travel.

The present invention allows the capacitance of the coated wire to be affected not only by the temperature of the insulation in the extrusion head, but also by the manner in which the insulating plastic material is cooled and expanded. Between the extrusion head and the movable vat, the coating spans a certain path while in the temperature range where chemical changes occur and, in particular, gas evolution occurs. The final structure of the coating follows these changes.
Thus, during a given speed, the structure follows a path of coverage between the outlet from the extrusion head and the inlet to the movable tub.

In order to solve the above-mentioned problems, the present invention firstly provides an extruder for expanded plastics having a head through which a metal wire passes, and a device for cooling the coating applied to the metal wire while passing through the head. A movable bucket,
A method for adjusting metal wire coating equipment is provided, which comprises a device that continuously measures the capacitance of the coated wire after cooling, and the position of a movable tub is adjusted by measuring the capacitance.

Is the temperature itself adjusted by the position of the movable tub?
Adjustments can be made directly by capacitance measurements or by simultaneous adjustment of the coefficients.

The invention also comprises means for displacing a movable tub in the direction of travel of the metal wire for movement toward or away from the extruder, the movable tub displacing means being controlled by a signal emitted by a capacitance measuring device. An apparatus for carrying out the above method is also provided.

In certain particularly preferred embodiments, the temperature of the extruder cylinder is regulated by the movable barrel position, or by a capacitance signal, directly or parallel to the movable barrel, or by using both coefficients simultaneously.

Various embodiments of the apparatus and various aspects of the method according to the invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an extruder cylinder 1 enclosed in a heating element 2 and a protective jacket 3.
The screw 4 has a fluid plastic material 6 attached to the head 5.
pressure weld. The metal wire 7 passes through a lateral passage in the head 5 and the plastic material 6 passes through a lateral passage through which the metal wire 7 passes and finally comes to a die 8 placed at the metal wire in the form of a tubular layer. It is press-fitted into the duct placed in the A movable bucket 9 is arranged coaxially with the die 8 and close to the bottom. This rectangular movable trough 9 has a square or U-shaped cross section and consists of guiding elements (not shown) for the coated wire 7 and a device for applying water to the wire. Upon entering and exiting the movable tub 9, the coated wire 7 passes through the front wall through an appropriately sized opening. A drain is provided at the bottom of the movable tub 9. After passing through the movable tub 9, the wire 7 is fixed and equipped with a gauge 11 connected to a device similar to that provided in the movable tub 9 as well as a device for continuously measuring the capacitance of the coated wire. Enter bucket 10.

To make the above measurements, the covered wire 7 is grounded,
A gauge 11, which is one of the arms of the capacitance bridge, is connected to the bridge.

The mechanical part of the equipment described further comprises a toothed rack 12 mounted along the movable trough 9 as shown in FIG. This rack 12 meshes with a pinion 13 driven by an electric motor 14. The connection between the pinion 13 and the electric motor 14 is shown in the drawing only as a single line diagram. In practice, it consists of a gear train and a belt-pulley drive or chain drive, all of which are connected to the movable tub 9 as the electric motor 14 rotates.
moves laterally. For this purpose, the movable tub 9 is provided with guide rails by means of rollers or runners. In FIG. 1, the movable tub 9 is shown in plan view in a position corresponding to the maximum permissible displacement toward the head 5. The path of the movable tub 9 is equal to the length of the rack 12.

The openings and guide slides in the front and rear walls of the movable tub 9 are designed to allow the metal wire to move laterally, so the movable tub 9 is movable in the axial direction of the covered wire.

FIG. 2 illustrates various designs of electrical equipment for regulating the equipment described in detail. FIG. 2 then illustrates an embodiment of the method in which the capacitance is kept constant simultaneously and directly by the displacement of the movable tub 9 on the one hand and by the temperature control of the cylinder 1 as a function of the position of the movable tub 9. ing. FIG. 2 illustrates the coated wire and gauge 11 whose capacitance is measured.

In the capacitance measuring device 15, the measurement is amplified and compared with a signal corresponding to the desired capacitance value. The output signal of the measuring device 15 is therefore an error signal corresponding to the amplitude and sign of the deviation of the measured capacitance from the reference value. The signal is passed through 16 filters and then sent to the controller 17. And power amplifier 1
8 starts and stops the electric motor 14 or changes its direction of rotation, all so that the electric motor 14 moves the movable tub 9 as soon as the capacitance deviation is measured. If the measuring capacitance is too low,
The expansion time of the plastic material is increased and therefore the movable trough 9 must be close to the extruder head 5. If the measurement results indicate an error of the opposite sign, the movable pail 9 must be moved away from the extrusion head 5. Because the capacitance measuring device 15 continuously measures the high speed of the metal wire 7, the correction is made practically instantaneously. That is, as soon as the capacitance reaches the reference value, the movable tub 9 stops.

The position of the movable tub 9 is measured with a suitable detection device. The detection device is built into the electric motor 14, for example, and consists of a tachometer of the pinion 18. The displacement of the movable tub 9 in fact ensures rapid adjustment and ensures that the capacitance of the coated wire 7 remains at a constant value.
However, from a long-term point of view, it is important to maintain the movable tub 9 in a substantially relatively stable operating position. Therefore, if the movable tub 9 moves away from the extrusion head 5 as a result of a change in the temperature range of the extruder, then the temperature range
Corrections must be made so that the movable tub 9 can return to its original position after a certain period of time.

The signal sent from the control device 17 to the cylinder temperature control device 19 is also filtered and formed via a conductor 21 to a temperature regulator 24 which controls either the heating element 2 or the cooling system. Controls the transmission of signals to the distributor 20. Usually heating element 2
The temperature is adjusted to a constant temperature by a temperature regulator 24 connected to the cylinder 1 through a thermocouple 23.

The temperature regulator maintains the cylinder area in which the thermocouple 23 is set at essentially the same temperature. In order to apply the command signal coming from the control device 19, a resistor is connected in series with the thermocouple 23 and a device is provided for transmitting a signal from the distributor 20 to each terminal of the resistor. The aspect of the signal is equivalent to a modification of the measured value.

The distributor 20 is equipped with an adjustment member that can freely adjust the operation of each signal in the corresponding thermocouple 23. It is known that in practice it is sufficient for the regulating element to act on the last heating element of the cylinder element in order to obtain the desired change in the temperature of the plastic material leaving the extrusion head 5.

The time constant of the correction system producing temperature changes is of course much larger than that of the system operated by the displacement of the movable tub 9, so that although the first correction occurs due to the displacement of the movable tub 9, the position of the latter system is on average It is the temperature of the cylinder that is adjusted to ensure that it stabilizes around the value and gives a constant capacitance value in the long run.

The devices mentioned above, in particular the gauge 11, the capacitance measuring device 15, the filter 16, the control device 17,
Amplifier 18, controller 19, distributor 20, and regulator 24 are all conventional devices known for use in some types of control equipment.

The signal resulting from the capacitance measurement is used to activate the electric motor 14 which displaces the movable tub 9, thus varying the length of the path through which the coating is made between the point where cooling begins and the extrusion head 5, with respect to the capacitance value of the wire. It was discovered that it was possible to produce coated wires that met the strict specifications imposed.

Look at the movable position where the capacitance value is adjusted,
It is possible to shorten the capacitance stabilization time and improve the production output of the insulated telephone wire extruder equipment.

The reaction speed of the control circuit passing through the electric motor 14 and the movable tub 9 is relatively fast, the actuating circuit from the movable tub 9 or the device 17 on the heating system is relatively slow;
Repetitive back and forth movements of the movable tub 9 are eliminated and the control function is therefore stabilized with simultaneous heating of the cylinder adjusted by the position of the movable tub 9 and capacitance measurements. The heating intensity is thus continuously monitored and contributes to maintaining the capacitance of the wire per meter of travel at a value as close as possible to the reference value. The equipment detailed in this manner is capable of producing telephone lines having a capacitance per meter meeting the exacting specifications required.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of extrusion equipment using the apparatus of the present invention, and FIG. 2 is a block diagram for controlling the same extrusion equipment. 1... Extruder cylinder, 2... Heating element, 3...
...protective jacket, 4...screw, 5...head,
6...Fluid plastic material, 7...Metal wire, 8...
...Die, 9...Movable tub, 10...Fixed tub, 11...
... Gauge, 12 ... Toothed rack, 13 ... Pinion, 14 ... Electric motor, 15 ... Capacitance measuring device, 16 ... Filter, 17 ... Control device, 18 ... Power amplifier, 19 ... Control Device,
20...Distributor, 21...Conductor, 23...Thermocouple, 24...Temperature controller.

Claims (1)

[Claims] 1. An extruder for molten plastic material, an extrusion head to which molten plastic from the extruder is supplied and which coats the molten plastic around a metal wire passing through the extrusion head, and a metal wire extruded from the extrusion head. a fixed tub for cooling a plastic coating layer coated with
means for the regulating device to control the temperature of the extruder; and means disposed within the stationary tub for continuously measuring the capacitance of the covered wire;
disposed between the extrusion head and the fixed tub;
and a movable tub that is provided with means for displacing in the running direction of the metal wire so as to approach or separate from the extrusion head, and a movable tub that cools the coating layer of the metal wire extruded from the extrusion head, A control device detects the deviation between the output signal from the means for measuring the capacitance and the capacitance at the reference value, and sends it as an error signal;
This signal controls the means for displacing the movable tub and is input to a cylinder temperature control device that controls the temperature inside the extruder to control the temperature and obtain a coated wire having a constant capacitance. Adjustment device for metal wire coating equipment.