NL8100554A - METHOD AND APPARATUS FOR REDUCING PLASTIC AND / OR RUBBER MATERIALS - Google Patents

Abstract

A method of disintegrating plastics and/or rubber material, such as the plastics and/or rubber casings of metal cores, for the purpose of recovering the metal from scrap cables for example. The material to be disintegrated is cooled to a temperature at which it becomes brittle. The embrittled material is then subjected in at least one station to mechanical oscillations which cause the material to disintegrate. The oscillations suitably have a frequency in excess of 30 Hz and an amplitude of about 2-3 mm. The oscillations can be imparted with the aid of a vibratory device with which the embrittled material is brought into contact.

Description

¥ y 813028 / Keijser

Short indication: Method and device for comminuting plastic and / or rubber materials.

The invention relates to a method for comminuting plastic and / or rubber materials, such as the sheaths of plastic and / or rubber, around metal cores, wherein the plastic and / or the rubber material is cooled to a temperature at which it becomes brittle. than to be reduced. The invention also relates to an apparatus for carrying out the method.

A method has long been sought in which the rubber or plastic sheaths of metal cores such as the copper or aluminum cores of insulated cables, copper pipes and the like can be easily and quickly separated from the cores, and in which not only the material of the shell is completely separated from the metal core, but the various components can also be easily separated accurately, so that both the metal and the material of the shell can be reused.

The most commonly used method up to now has been to burn away the material from the jacket. However, this method creates air pollution that is harmful to the environment and is not permissible. Furthermore, when using this method, the 20 mante materials cannot be used again. In another known method, the electrical cables were subjected to fragmentation, i.e. they were cut or chopped into small pieces so small that most of the insulation material automatically fell off the conductors. However, this method is relatively time consuming and expensive, while additionally creating major separation problems.

British Pat. Nos. 1,303,167 and 1,407,996 disclose methods in which the jacket material is first cooled to a temperature where it becomes brittle, then mechanically processed. A serious drawback of the device according to the first of these two publications is that it is relatively complicated; both a hammer unit and a subsequent separator drum are used. For example, when a material enters the device at a certain time that has not cooled sufficiently, the device will become clogged and blocked by a difficult to remove, but stuck 81 00 55 4 - 2 mass. The danger of excessive heating of the cooled material also arises from the fact that a considerable part of the kinetic energy coming from the hammer is converted into heat energy in the jacket material. Furthermore, the necessity of using relatively short pieces of the conductor or core materials seems to cause serious separation problems, especially in the case of thin metal conductors, so that the recovered plastic and / or rubber materials do not have the desired quality (purity), so that the value of the material is significantly reduced.

In the method described in the other mentioned publication, British Patent Specification 1 407 996, a continuous length of the guide is displaced in a device and successive parts of that length are alternately processed with a combined hammer and cutting head. This device has the following drawbacks. Because the mode of operation is intermittent and because only a single conductor length can be handled at a time, the operating speed or capacity is low. The method is best suited for large cables and cannot be applied efficiently with very thin cables, or with cables containing a number of separate insulated conductors. Furthermore, the hammer device must be accurately adjusted to the dimensions of the treated cable and the cable must be of relatively long length.

The main object of the invention is to provide a method and device of the above-mentioned type in which the listed drawbacks are obviated and with which plastic and / or rubber material can continuously be reduced in a convenient manner, ie for separating plastic and / or 30 metal core rubber sheaths, regardless of the length, dimensions and number of cores in the workpiece, and where several workpieces can be treated simultaneously.

The invention is based on the idea that the known technique of embrittling the material and then comminuting it with a hammer or cutting tools is replaced by a technique in which the embrittled jacket material is subjected to mechanical back and forth. 81 0 0 55 4 ft - - 3 - movements causing this material to decompose. The oscillations are formed by pressure waves or pressure pulses of constant frequency, each of which has insufficient energy to cause the material to collapse but which, when passed through the material in the form of a substantially continuous mechanical oscillation, causing the material to disintegrate due to the vibrations prevailing there. Preferably, the frequency of the oscillations is above 30 periods per second.

The oscillations can be started, for example, with the aid of a vibrating device with which the object from which the mantle is to be removed is brought into contact. Preferably, the objects are passed between a vibrating plate and a fixed supporting plate. This makes it possible, among other things, that when 15 cables are treated, a large number of cables can be processed simultaneously in the space between the plate and the bearing surface.

By mounting the vibration plate on a spring suspension, the width of the gap will automatically be adjusted to the dimensions of the workpieces, for example the cable, so that the device can be used for the workpieces of different sizes without the need to re-install the device. set. Investigations have shown that the said oscillations can be transferred effectively between the different insulation layers of a cable or a bundle of cables, so that the method according to the invention thus offers the possibility of effectively removing insulation material from multi-wire cables consisting of several separate insulating jackets ; it is even possible to process batches of cables.

When the invention is used, a substantially complete separation is obtained between the metal and the insulating material, in order to make the recovered material more valuable than what has been recovered in the known processes.

In a favorable embodiment of a device according to the invention, a vibrating plate is used, which is suspended from springs arranged at the ends of the plate, while the vibrations in the plate are induced at a location closer to the springs on one of the ends then the other, the plate being arranged so that the workpieces to be treated are introduced into an interspace between said one end of the plate and a fixed bearing surface. This means, among other things, that in the case of jackets that are not easily worked, energy will be stored in the rear springs and will be returned with a certain transmission ratio to the front edge of the plate, in which to give a greater striking force. Preferably, the front end of the plate forms an angle to the bearing surface, which means that a cable or workpiece will be successively treated in a narrowing gap, which is of particular advantage in the case of multi-wire cables.

The invention will be explained below with reference to the appended drawing.

Fig. 1 shows an overview of a machine for disintegrating the insulating sheaths of cables using the method of the invention, and

Fig. 2 shows in detail a vibrating device according to the invention which forms part of the installation according to FIG. 1.

In the drawing, 1 generally indicates a part of a stretching device with a cutting device '2. The stretcher is constituted by a number of rollers 3 which cooperate to stretch an incoming cable 4. These stretchers are known and will not be described in further detail here.

As shown in Fig. 1, the stretched and cut cable lengths 5 are introduced into a cooling line 6; in practice, the stretching device has a position 90 ° different from that shown in the drawing, so that the cable length is transverse to the cooling line 6. The cooling line consists of an elongated insulating housing 7 connected to a funnel-shaped inlet section 8 for accommodating the cut cable lengths 5. A rotary vane device 9 for the feed is arranged in the feed section 8 to feed batches of cable lengths 5 into the cooling line. The feeder 9 cooperates with a plunger 10 to continuously feed cable lengths 5 through the cooling line. To facilitate this further supply of cable lengths 5, the cooling line can slope downwards relative to the 81 0 0 55 4 - 5 horizontal.

In the cooling line 6, a number of pipes 11 discharge, through which liquid nitrogen flows from a vessel 12. In order to effectively cool the cable lengths 5, a number of fans 13 are present to ensure that the nitrogen flows properly through the cooling line 6.

The line 6 is also provided with a suction fan 14 for the controlled discharge of the gas. The presence of rotating blade feeder 9 prevents uncontrolled refrigerant losses.

The temperature in the cooling line 6 is sensed by one or more temperature sensors 15 which cooperate with a converter 16 which produces an electrical signal corresponding to the temperature sensed by one or more sensors 15.

This signal is compared in a comparator unit 17 with a temperature reference 18 for the setting. The comparator 17 is designed to generate a control signal which controls a control valve 19 in the delivery line of the nitrogen vessel 12. By means of this control equipment it is possible to keep the different sections of the cooling line 6 at any desired temperature level.

Cable lengths 5, whose jackets are brittle as a result of the cooling, are fed from line 6 to an apparatus in which the jacket material which has become brittle disintegrates. The means for disintegrating are formed by a vibration unit 20 in which the rigid cable lengths 5 are supplied by means of a plunger device 21.

Referring now to FIG. 2, it will be seen that the vibration unit 20 includes a vibrating plate 22 suspended from two front springs 23 and two rear springs 24. The front ends of the beams 25 are interconnected by a rod 27. In the illustrated embodiment for adjustment of the height of the front ends of the beams 25, those ends are movable in slots in fixed holders 28 and can be secured therein in selected positions.

A vibrator is arranged on the plate 22, which in the shown embodiment consists of two unbalanced flywheels 29 which are driven by an electric motor (not shown). Vibrations of the desired amplitude and frequency can be obtained by appropriately adjusting the weight, balance and peripheral speed of the rotation of the flywheels 29 in a manner known per se. The vibrator will be placed closer to the front springs 23 than the rear springs 24.

Denoted by 30 is a fixed bearing surface which at the rear end of the vibrator changes into a grid construction consisting of elongated bars 31. Below the grid 31 there is a tray 32 for receiving the disintegrating jacket material, while the at the end of the grid is a tray 33 for collecting the metal cores 34 of the cable lengths.

When the device is operating, a batch of stretched and chopped cable lengths 5. became brittle in the cooling line 6, supplied to the interspace between the vibrating plate 22 and the fixed supporting surface 30 by means of the plunger 21. The decreasing height of the interspace between the plate and the supporting surface results in successively the mantles of the incoming cables are processed as they pass through that gap. Because the sheath-20 material is completely rigid, good propagation of the vibrations generated by the vibration plate 22 is obtained by all the sheaths in all cables, effectively separating both the outer sheaths and separate sheaths around individual conductors by the oscillations in the material. The device 25 can also effectively process thin conductors located in batches, i.e. the conductors can be applied to the device in multiple layers. .

Due to the way the plate 22 is suspended and the vibrator is located on that plate, when heavy cables enter 30 or cables that are not easy to process, or thick bundles of conductors are fed to the device, the front end of the plate are lifted to thereby compress the springs 23 and allow the springs 24 to expand. The energy thus stored in the rear springs 24 is then returned with a given transmission-35 ratio, which is determined by the location of the vibrator on the plate 22, as a downward force on the front end of the plate. . The thus obtained 81 0 0 55 4 - 7 - increased force facilitates the disintegration of the sheaths of the cable lengths supplied to the vibrator. Good results have been achieved in studies in which the vibrator was placed on the plate 22 such that the ratio of the distances between the * 5 vibrator and the front and rear springs, respectively, was 1: 4.

For example, the spring suspension of the vibration plate 22 shows that the disintegrator can be used effectively for cables whose diameters differ within very wide limits and that a greater impact is obtained against cables of large diameter or cable sheaths that are not easy to process. When the cables to be treated have exceptionally large diameters, the front end of the plate 22 can be lifted using the adjusting means 27 and 28.

The flywheels 29 of the vibrator are rotatably mounted in the direction of arrow A, so that they automatically move the cables 5 further in the space between the plate 22 and the support surface 30. The vibrating movement of the plate 22 also creates a fan effect which effectively pushes the disintegrated jacket material through the grid formed by the bars 31 until it enters the bin 32.

Very good results were obtained when conducting investigations when the vibrations generated by the plate 22 had an amplitude of 2 to 3 mm and a frequency of 50 Hz. Despite this relatively low amplitude, a good disintegration effect was obtained even in the case of cables with a relatively large sheath thickness, which illustrates that the device does not operate in the known manner by compression, but that the relatively high frequency is also decisive meaning. The frequency should not be less than about 30 periods per second, including from the mechanical setup point of view, but frequencies higher than 50 Hz can also be used. In the tests performed, the frequency used was 50 Hz because in practice that frequency can be easily obtained with the use of an electric motor. The fact that the device does not function like a conventional press is also reflected in the low power requirement. In the aforementioned tests, the vibrator was driven with an input power of only 500 W, with a good 8 1 0 0 55 4 - 8 result. However, in order to increase the capacity of the device, a higher input power must be used, for example 1-1.5 kW. Under all circumstances, however, the power input will be very low per kilogram of disintegrated material, compared to the energy required by known devices intended for the same purpose.

The low power input means that there is no danger of the jacket material being overheated as the cable lengths pass through the vibrator. Heating of the jacket material has been found to be so small in practice that, if desired, different vibrating devices can be placed one behind the other.

A very important advantage attainable with the invention is that 100% of the shell material is removed from the metal cores. This means that the metal and cladding material recovered with the device have a high commercial value. Because a number of cable lengths can be processed simultaneously over the entire length thereof, the capacity of the device is very high.

The device is also very easy to handle and has a simple construction. Normally no settings are required when cables with different dimensions are treated.

In the illustrated embodiment, the cut cable lengths 5 are fed transversely to the device. A suitable length is of the order of a meter. However, both shorter and longer cable lengths can be treated. It is also possible to run a number of continuous cable lengths axially through the vibrator according to the invention. The cable can be arranged to run freely from one coil to the other during the passage through a cooling line and a vibrator according to the invention. In this way, the metal core can be recovered in a single length and optionally reused without first being melted again.

The above-described embodiment of the cooling line 35 should be considered as an example only because it can be changed as desired. Furthermore, the nitrogen gas can be replaced by another gas, depending on the desired cooling temperature determined by the jacket material. This is known to the skilled person in this field and does not need to be discussed further. The vibrating unit can also be changed and it can for instance be made movable relative to the fixed support surface.

The use of vibrations to disintegrate plastic and rubber material according to the invention can also be used, for example, to remove coatings from copper pipes with a plastic layer and similar articles. Other objects can also be broken down with the method and device according to the invention, such as car tires. These are first divided into smaller pieces which are then embrittled and passed through a vibrator according to the invention, where the brittle rubber material decomposes.

The invention may also be modified in other respects, the common feature of all those embodiments being the use of mechanical oscillations to disintegrate rubber and / or plastic material that has been embrittled by cooling. The oscillations can be generated by means of a vibrating device or in some other way, for example by powerful blows using compressed air or the like.

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Claims (10)

1. A method of disintegrating plastic and / or rubber material such as the plastics and / or rubber sheaths of metal cores, wherein the material to be disintegrated is cooled to a temperature at which it becomes brittle and then disintegrates falling, characterized in that the embrittled material in at least one station is subjected to mechanical oscillations which cause the material to disintegrate. A method according to claim 1, characterized in that the embrittled material is subjected to oscillations with a frequency above 30 periods per second. Method according to claims 1 or 2, characterized in that the oscillations are produced by means of a vibrating device with which the embrittled material is brought into contact. Method according to claim. 3, characterized in that the embrittled material is fed between a vibrating plate and a fixed bearing surface. 5. Device for disintegrating plastic and / or rubber material such as the plastics and / or rubber sheaths of metal cores, which device comprises means for cooling the material to be disintegrated to a temperature at which the material becomes brittle, and means for subsequently disintegrating the embrittled material, characterized in that said disintegrating means (20) are configured such that the embrittled material is subjected to mechanical oscillations which result in the material disintegrating. Device according to claim 5, characterized in that the frequency of the oscillations is above 30 periods per second. Device according to claim 5 or 6, characterized in that the amplitude of the oscillations is approximately 2-3 mm. Device according to any one of claims 5 to 7, characterized in that said means (0) for subjecting the embrittled material to mechanical oscillations are formed by a vibrating plate (22) placed a short distance above a fixed bearing surface (30) to form a gap intended to pass the embrittled material while in contact with both the vibration plate and the bearing surface. 9. Device according to claim 8, characterized in that the vibrating plate (22) is suspended from springs (23, 24) which are arranged at mutually opposite ends of the plate, in that the oscillations on the plate are pressed in one place which is closer to the springs (23) at one end than to the other springs; that the device is designed such that the material which has become brittle passes through the passage between one end of the vibrating plate (22) and the fixed supporting surface (30), and that at least this end 15 of the vibrating plate forms an angle with the supporting surface. Device according to claim 9, characterized in that the distance between the location on the vibrating plate (22) where the vibrations are pressed and the springs (23, 24) at the respective ends of said plate is within a ratio of about 20 1/4. 8100554