DE2422052A1 - METHOD AND DEVICE FOR CONTROLLING A SYSTEM INTENDED FOR COVERING METAL WIRE - Google Patents

Description

30,705

MAILLEFER S.A.

"Method and device for regulating a system intended for sheathing metal wires"

j Systems for sheathing metal wires are used to - |

I. I.

'For example, to produce insulated lines, as they are in the telephone j

j. ί

construction and generally used in electrical appliances «j The need for such lines is constantly increasing, which is why very powerful reduction systems have to be developed Such systems generally include an extruder, the head of which guides the wire passing through it and the one on the wire; -Applying a layer of molten plastic. The one on this

! Way sheathed wire then runs through a cooling case in which

one or more jets of water are directed at him.

■ To increase the production capacity of such systems, one seeks to increase the speed at which the wire runs through the head, with speeds of more in the end than 2000 m / min for conductors with a diameter of a few tenths of a millimeter ! knives can be achieved. In the production of insulated partitions however, the quality conditions relating to the wire sheathing must be adhered to very precisely; the quality conditions come in the amount of wire capacity per running Met8r to

ι ■ ■. -

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Expression, and this value must be entered within very narrow limits

hold u / earth. If the sheath consists of a foamed polymer, the capacitance depends on the conductor v / on the display; mung degree of the material, which in turn depends on the ^temperature: is. 'j

There are already known controls that the value of this temperature determine and operate switches that act on the heating elements located in the extruder barrel to raise this temperature keep constant. One has to look for improvements of this kind

Tried, facilities, the main disadvantage of which is to be seen in their inertia, by not the temperature in the extruder head but determined the wire capacity after cooling the jacket. Furthermore, continuously operating capacitance measuring devices are known, the measured value with a predetermined setpoint

j compare. Such devices provide an error signal which shows the difference between the measurement and the target according to size and; Sign indicates. This signal is used to control the cylinder

heating or, in certain cases, the wire speed

j used.

; However, all of these known methods are insufficient because of them to work too sluggishly and too imprecisely as soon as you have admonished the above

■ wants to use very high throughput speeds, and the invention is therefore based on the task of developing a method and a device that allow high production

j speed to produce a sheathed wire that will:

made requirements in terms of capacity per running Meters are enough.

409851/0988

The invention is based on the finding that the capacity of a coated wire, extend not only won the temperature of the insulating material in the extruder head but also depends on the manner in which the cooling and the foaming of the Kunststoffmate- ¹ rials. Between the extruder head and the cooling housing, the jacket runs through a certain section of the path, on which it is still in a temperature range which gives rise to chemical changes, in particular to the release of gases. The final structure of the jacket will depend on these changes. This means: the structure of the jacket depends on the distance that the jacket travels from its exit from the extruder head to its entry into the cooling housing for a given throughput speed.

In order to solve the problem mentioned, the invention provides a method to regulate a system intended for sheathing metal wires, which are processed from a foam plastic Extruder, through the head of which the wire runs, a cooling housing for cooling the coating layer that is applied to the wire as it passes the extruder head, and the capacity of the coated wire continuously after it has been cooled determining measuring device consists; the method is characterized in that the position of the cooling housing according to the , Capacity-Messiuerts is controlled.

The temperature itself can be controlled according to the position of the cooling housing or directly according to the capacitance measuring device, parallel to the drive of the housing. '

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The invention is also based on the object of developing a device for carrying out the method, which device is characterized in that a device is provided for moving the cooling housing in the running direction of the wire, so that the cooling housing in the direction of the extruder head and 'won it can be moved away, and that the means for displacing the cooling housing is referred by a signal controllable, which won the capacitance measuring device is delivered, or at the same time by the two parameters ^1.

In certain particularly advantageous embodiments of the invention the temperature of the extruder cylinder is also either depending on the position of the cooling housing or immediately and controlled in parallel with the cooling housing by the capacitance signal.

The drawing shows various embodiments as examples the device according to the invention and explains various Ways to practice the procedure.

Fig. 1 shows schematically a coating system, with which the method according to the invention can be practiced; 2 shows a first possibility in a block diagram

to carry out the procedure; :

ι Fig.3 shows a second possibility in a block diagram

to carry out the procedure, and

4 shows a third possibility in a block diagram for carrying out the method, wherein the movable cooling housing is controlled in accordance with the wire capacity. j

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Fig.1 shows an extruder cylinder 1, of heating jackets 2 and

a protective jacket 3 is surrounded. The screw 4 promotes in

. Direction of the head 5 a flowable plastic material 6. By
! the cross channel of the head 5 runs the metal wire 7, while the

I plastic material 6 is pressed into supply channels around the

are arranged around the transverse channel traversed by the wire; the
Plastic material enters the nozzle 8, where it forms a tubular layer around the wire. In the. A cooling housing 9 is arranged at a small distance from the axis of the nozzle 8. This
elongated housing has a rectangular or U-shaped cross section and has (not shown) guide elements for the
sheathed wire as well as outlets from which the water on the; Wire is injected .. At the entrance and exit of the housing i, the wire penetrates the housing walls in openings of a suitable width. , There is a drain in the bottom of the housing. After this
j the wire has left the housing 9, it enters a second, j j stationary cooling housing 10, in which nsben ejection i

\ I

openings, similar to those which have undergone working in the cooling housing 9 \

! find, a measuring device 11 is located, which is still to be loaded on the below ^; i writing devices is connected and that the capacity of the; Measures sheath continuously. To carry out this measurement!

j, the wire 7 is connected to ground, and the measuring device 11, which has an i j - - -i

; Branch of a capacitance measuring bridge is connected to this bridge

ΐ ~ ⁱ

j switches. j

The mechanical part of the system described usually also has a

Rack ■ 12, which, as can be seen in Fig. 1, on the longitudinal

'Side of the cooling housing 9 is attached. With this rack; I ι

j meshes with a pinion 13 driven by an electric motor 14

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will. The connection between pinion 13 and motor 14 is in the

j drawing only indicated schematically. It can be used as a gear drive

: work or as a belt or chain drive,! In any case, with the engine 14 running, the cooling housing 9 is displaced in the longitudinal direction. For this purpose, the housing can be guided;

■ support rails slide or roll. In Fig.1 is the cooling housing drawn in plan in a position that is its maximum; Displacement in the direction of the head 5 corresponds. The ver i The sliding distance of the housing 9 is the length of the rack 12 i

■ adapted. Since the in the front and the rear wall of the housing ses cut openings and the guide members are attached so that the wire can be moved in the longitudinal direction, can Housing 9 can also be moved freely in the longitudinal direction of the wire.

Figures 2, 3 and 4 show different arrangements for the electrical equipment that effect the regulation of the system described. FIG. 2, for example, shows a possibility for carrying out the method in which the capacity is on the one hand by moving the housing 9 and on the other hand by controlling the temperature of the cylinder 1 as a function of the
Position of the housing 9 is kept constant. In this figure, the wire 7 and the measuring device 7 can be seen, which makes the measurement of the capacitance. In the capacitance measuring device 15, this measured value is amplified and compared with a signal that the
Setpoint corresponds to the capacity. The output signal of the measuring; device 15 thus represents an error signal, the size and ' sign of the difference between the measured capacitance; and corresponds to the nominal value of the capacity. The signal is filtered in j 16, then transmitted to the control unit 17, whose

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• Power stage 18 turns the motor 14 on or off or his Direction of rotation reversed, and to / ar so that the motor moves the cooling housing, as soon as a capacity difference is determined. 'If the measured capacitance is too small, the time span is during which foaming takes place in the plastic material, too long, and as a result the cooling shroud must be closer to the Extruder head are guided. If the measurement result indicates a deviation with the opposite sign, the cooling housing must further away from the extruder head. The capacitance meter works continuously. Because of the high throughput speed of the wire, the correction is practically instantaneous; as soon as the capacity reaches the setpoint, it stays that way Cooling case in place.

The position of the movable cooling housing 9 is also determined by a suitable detector device. The detector can for example built into the engine 14 and used as a revolution counter for the Pinion 13 be executed. The signal corresponding to the Psjöition of the cooling housing 9 is transmitted to a control unit 19, which ; generates a signal that controls the temperature of the cylinder. Thus, the displacement of the cooling case 9 can bring about a quick regulation, whereby the capacity of the covered wire j is kept at a constant value. Viewed over a longer period of work, however, it is important that the movable cooling housing at least approximately a relatively stable

adheres to the whip position.

If now the cooling housing is due to a change in temperature conditions removed from the extruder head in the extruder, it is advisable to correct the temperature conditions so that

409851/0986

with the cooling housing is returned to its original position after a certain period of time. The signal transmitted into the device 19 causes a filtered and formed signal to be sent to the distributor 20; the signal reaches the temperature controller 24, which controls either the heating element 2 or a cooling system. Normally, the heating elements 2 are kept at a constant temperature by the temperature regulators 24 with the aid of thermocouples 23 arranged on the cylinder 1. The regulator; keeps the cylinder area on which the thermocouple assigned to it is arranged at a constant temperature. To this tax ^! In order to superimpose commands coming from the device 19, resistors can be connected in series with the thermocouples and the signals coming from the distributor 20 can be fed to the terminals of these resistors. The appearance of a signal is therefore equivalent to a change in the measured temperature. The distributor can be provided with adjustment means which allow the effect of each signal on the corresponding thermocouple to be controlled at will. It has been found in practical operation that it is sufficient to act on the last-mentioned heating elements of the cylinder in order to bring about the desired influence on the temperature of the plastic material at the outlet of the extruder head.

In the embodiment shown in Figure 2 arrangement thus causes a displacement of the cooling vessel, a change in the heating or the cooling conditions of the extruder barrel produced, from which ER is '■ is that the housing 9 in its initial position or in the proximity' is returned to this position .

409851/0986

j The schematic drawing Fig. 3 illustrates another temperature control method. The capacitance measuring device 11 generates, as shown in FIG.
: a signal that is amplified in the device 15 and with a set point

is compared. The device 15 sends out an error signal that
f filtered in 16, amplified in 17 and

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direction 18 for the motor 14 and on the other hand in the control unit

direction 19 is transmitted. The time constant of the system causing a temperature change is naturally much greater
than that of the system which, by sliding the housing 9
takes effect so that the first correction can be made by moving the
Housing takes place that the position of the housing changes quickly
stabilized around a mean value, while the cylinder temperature is controlled in the long term, in order to achieve a constant capacity Greater.

The schematic drawing Fig.4 shows a simplified device again ^: the one that can be sufficient when certain parameters ratio-!

'are moderately stable and the ι given for the value of the capacity Limit values are not chosen too narrow. The capacitance measurement signal j

·

of the measuring device 11 is amplified in the device 15 and with the target! worth compared. The device 15 sends out an error signal that j

■ is filtered in 16 and amplified in 17, as it was with the previous ones; procedures described has been the case. The error- j

"-j

: signal is only fed to the engine control 18. The Ge i

housing 9 is however provided with means, such as with limit switches, ί the trigger an alarm device 22 when the displacement over \ exceeds a limit value. The alarm device prompts the operator to intervene manually. j

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The devices indicated above, in particular the measuring device 11, the

: Capacitance meter 15, the filter 16, the control unit 17, the

: Amplifier 18, the control unit 19, the distributor 20, the control

devices 24 are commercially available devices that are known per se

ι and are already used for certain control devices. ^; i

Practical experience has shown that it is possible

: To be the effect of the originating from the capacitance measurement signal to a motor which can adjust the cooling shroud and allowed to change with the length of the path ^so-1, of the shell between the extruder head and dam point at which cooled the shroud begins to cover is to produce a sheathed wire that meets the strictest requirements that can be made with regard to the value of the wire capacitance. This regulation of the position of the movable cooling housing in accordance with the capacity leads to a shortening of the

^! Stabilization time of the capacitance and improves the performance of the '■ jacketing equipment for insulated telephone wires.

. Finally it could also be found that with simultaneous Using the control processes shown schematically in FIGS. 2 and 3, results can be achieved which are those according to only surpass one of these control methods. Since the response speed of the running through the motor 14 and the cooling housing 9 Control loop is relatively high, while the input

\ Speech rate of the via the housing 9 or via the input

iheit 17 acting on the heating system circuit relatively low ι is drig, oscillations of the cooling case 9 are avoided, and as a result, the control effect is stabilized by the

, Cylinder heating at the same time according to the position of the cooling

409851/0986

housing and the capacitance measurement are controlled. The heating power is thus continuously superior and experiences constant, | but very minor changes, due to the capacity of the wire-j tes are kept extremely close to the target value per running meter! can. In this way, with the described system! Establish telephone wires with a capacity per running meter equal to meets the strictest requirements.

Claims;

409851/0986

Claims (9)

30,705 patent on proverbs: 1. Learn how to regulate one for sheathing metal wires certain system, consisting of a foam plastic processing extruder, through whose head the wire runs, a Cooling housing for cooling the sheathing layer that is applied to the wire as it passes the extruder head, and a The capacity of the coated wire after its cooling is continuously determined by a measuring device, ! characterized in that the position of the cooling housing is controlled in accordance with the capacitance measurement. ι 2. The method according to claim 1, characterized in that the position of the cooling housing and the temperature of the extruder cylinder can be controlled in accordance with the capacitance measurement. 3. The method according to claim 1, characterized in that ι the temperature of the cylinder according to the position of the cooling : housing is controlled. 409851/0986 4. Apparatus for performing the method according to claim 1; characterized in that means for displacing the; Cooling housing is provided in the running direction of the wire, so that ^! the cooling housing towards the extruder head and won him meg; is movable, and that said device for moving; of the cooling housing can be controlled by a signal that is sent by the Ka-! capacitance meter delivered. 5. Apparatus according to claim 4, characterized in that the cooling housing is provided with a sensor which has a position signal sends out, and that the said signal is on an input ' i direction for controlling connected to the extruder barrel; i heating or cooling elements are given. ' \ • 6. Apparatus according to claim 4, characterized by a ι ι '·. Capacitance measuring device (15) capable of emitting an error signal, ι the difference between the measured capacity and a ι adjustable capacitance-Sollujert corresponds, and that these Sig- j nal to a control member (18) for a device for moving of the cooling housing is transferable. 7. Apparatus according to claim 6, characterized in that the cooling housing has a rack into which one of the elec-> ; tromotor-driven gear engages, and that said Shlersignal can be transmitted in such a way to a member which actuates the motor is that it starts moving in one of its two directions of rotation and the cooling housing moves in the direction of translation According to the value of the error signal shifts A09851 / 0986 8. Apparatus according to claim 5, characterized by a device which regulates the temperature of the extruder cylinder either by the signal supplied by the capacitance measuring device or by a signal corresponding to the position of the cooling housing can be influenced. 9. Apparatus according to claim 5, characterized by a the temperature of the extruder cylinder regulating device, which by the signal supplied by the capacitance measuring device and by! the signal corresponding to the position of the cooling housing can be influenced « 409851/0986 Blank page