DE2824784A1 - PROCESS AND DEVICE FOR CONTINUOUS VULCANIZATION OF ELASTOMER MATERIAL, IN PARTICULAR CABLE INSULATION - Google Patents

Description

Procedure and device for MUNICH

continuous vulcanization. _{8 (} -of elastomeric material, especially- - * special cable insulation

Description:

The invention relates to a method and a device for continuous vulcanization and Cooling of elastomeric material, in particular for cable insulation, in particular insulation of cables that are intended for use under high electrical stress.

When insulating material is continuously vulcanized, the material is passed through a vulcanizing chamber containing a heat exchange fluid, e.g. a eutectic mixture of inorganic salts such as e.g. sodium and potassium nitrates or nitrites, with the mixture in the liquid phase over a temperature range is stable from 150 to 400 ° C.

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It is also known to be natural as an insulation material Rubber, SMl, polychloroprene, nitrile rubbers, stereo elastomers (e.g. polyisoprene and polybutadiene 1,4-cis), crosslinkable polyethylene or polypropylene and crosslinkable copolymers of ethylene and propylene or the like.

For stable coatings or casings, it is essential, especially if the casing is a is subjected to high electrical stress to ensure that the material as few as possible and contains the smallest possible cavities, in which an ionization of gases could take place, the one Breakdown of the insulation and destruction of the cable could result. The vulcanization of Crosslinkable material is used to reduce the formation of voids under high pressure carried out by steam (or more recently nitrogen). The use of gases and especially steam as a pressure-generating medium has the disadvantage that the medium has the tendency to diffuse into the insulation, which in the subsequent cooling of the insulation, the risk of cavity formation with it brings.

The vulcanization (or crosslinking) is also considered using a stable liquid medium

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Heat exchange fluid in a volcano! Sierkaamer been done that straight forward and in general is arranged inclined to the horizontal plane, although in some cases already a chain line Vulcanization chamber was used. However, it is also possible to use vertically arranged vulcanizing chambers. In addition to the vulcanization chamber, a cooling chamber is also provided for the vulcanized insulation. Such a device requires the application of pressure during vulcanization. Usually, Yasser is referred to as Cooling medium used.

Other forms of continuous vulcanization apparatus are known. For example, can a vulcanizing chamber can be provided in which the vulcanizing temperature is generated by radiant heat sources will. However, the present invention does not relate to such devices.

It is the object of the present invention to provide a method for continuous vulcanization and cooling of insulation material, as well as a device for carrying out the method, to create in which the continuous Vulcanization and cooling can be carried out in an advantageous manner such that a cable insulation is produced, which substantially does not have the above-mentioned disadvantages.

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282478A 1

A method of vulcanizing an elastomer Material, in particular insulation material according to the invention is characterized in that the material is passed through a vulcanizing chamber through which a stable liquid vulcanizing salt is circulated, the is maintained at the required vulcanizing temperature and under a predetermined pressure, and that the vulcanized Material is conveyed through a cooling chamber through which a gaseous cooling medium circulates under pressure which is of such a nature that it does not affect the crosslinking reaction and with the Material does not react.

According to an advantageous development of the method, the vulcanized material is initially partially cooled in a chamber through which cooled heat exchange fluid is circulated, and partially cooled material is then passed through the gaseous cooling medium.

According to another embodiment of the invention, the material can then be cooled with gaseous Cooling medium can be passed through a chamber with liquid coolant, through which a liquid coolant (preferably water) is circulated.

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According to a further embodiment of the invention the material is passed through a vulcanizing chamber that contains stable liquid vulcanizing salt under pressure, and the vulcanized material is then conveyed through a pre-cooling chamber, the liquid salt under pressure , then by a gaseous coolant and finally by a liquid coolant (preferably Water).

An apparatus for carrying out the process for the continuous vulcanization of elastomeric According to the invention, material comprises a vulcanizing chamber having an inlet and an outlet for the elastomeric material and means for circulating a liquid stable vulcanizing salt through the vulcanizing chamber at the required vulcanizing temperature and the required Pressure, as well as a cooling chamber connected to an outlet of the vulcanizing chamber with means for Circulating a gaseous medium under pressure which is of such a nature as to cause the crosslinking reaction does not affect and does not react with the material, the means for circulating the gas have a gas cooling device and a gas environmental pump. The stable liquid vulcanizing salt is preferably a eutectic mixture of inorganic salts.

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Means are also preferably provided for partially pre-cooling the insulation under pressure their entry into the gas cooling chamber, the means being a cooling device and environmental means for comprise a liquid coolant.

Preferably the liquid coolant is also a eutectic mixture of inorganic ones Salts, preferably of the same composition as the vulcanizing liquid. According to a pre-

-J ₀ ferred embodiment of the invention is drawn off the cooling liquid from the circulating liquid curing medium and cooled before it enters a pre-cooling chamber which is disposed between the vulcanizing and charged with gaseous cooling medium cooling chamber.

According to another form, in addition to the cooling chamber charged with gaseous coolant, a A chamber charged with liquid coolant can be provided, the means for circulating a cooling liquid (e.g. water) through the chamber and with the outlet of the gaseous coolant charged Chamber connected, but separated from this chamber.

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In another embodiment of the invention, there is between the one charged with gaseous coolant Cooling chamber and the vulcanizing chamber a pre-cooling chamber arranged and at the outlet of the gaseous cooling chamber one charged with liquid coolant further Cooling chamber connected.

Embodiments of the invention are explained in more detail with reference to the drawing.

Fig. 1 shows schematically a first embodiment of a device for continuous volcanoes

sizing of to an electrical cable made of extruded insulating material.

FIG. 2 shows a modification of the device according to FIG. 1.

According to FIG. 1, the device is connected to an extruder through which a cable 11 to be coated runs. As the cable 11 passes through the nozzle 12 of the extruder 10, it is coated with an insulation material and then a pre-cooling chamber 14, a cooling chamber 15 charged with gas and a final cooling chamber 16 charged with liquid, from which the insulated cable 17 is _{passed through a vulcanizing chamber 13 f} emerges, including being wound onto a cable drum (not shown).

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/ 13

The vulcanizing chamber 13 is attached to the extruder head connected by a connecting pipe 18 which is slidably mounted in the inlet end of the Vulkanisierknmmer 13 is. The tube 18 is slidably connected to the chamber 13 with a gas-tight seal and can be connected in a gas-tight manner a sealing collar 19 of the extruder head 12 can be connected. A vulcanizing medium (which will be explained in more detail is) does not come into contact with the extruder head 12, as it is through a (described below) Line 22 flows off. A compressed gas line 20 is connected to the pipe 18 and is used to provide the required To generate pressure in the chamber 13 and to maintain it. A similar gas duct 20a is at the rear end of the chamber 13 (with respect to the direction of movement of the cable) intended.

The vulcanizing chamber 13 is, as shown, arranged with a slope from the inlet to the outlet end. Instead of the straight-line shape of the chamber 13 shown, this can also have the shape of a chain line.

A connection unit 21 is provided between the vulcanizing chamber 13 and the pre-cooling chamber 14, which has an axially disposed passage through which the coated cable passes. This passage becomes surrounded by a number of supply bores for the volcanic agent which are parallel over part of their length

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282A784

to the axis of the connection piece and then at an angle run this axis so that they open into the chamber 13 at the cable outlet end. Optionally, the connection unit 21 can also be provided with an inlet for the vulcanizing agent which extends over part of its length the axial passage surrounds annularly, with a frustoconical ge r end region is provided, which is in the chamber 13 opens. The chamber 13 is in the area of the cable entry end with an outlet line 22 for the Vulcanizing agent is provided, and this is connected to a storage and heating tank 23 for the vulcanizing agent. Behind the connection unit 21 (in the direction of the cable movement) is a return line 23 for vulcanizing agent which is also connected to the tank 23. Furthermore, with the storage tank 23 is a Pump 24 connected, through which the vulcanizing agent via a line 25 to the connection unit 21 and from there can be pumped into the chamber 13. The vulcanizing chamber 13, the lines 22 and 25 and the tank 23 are preferably thermally insulated and provided with heating devices so that the vulcanizing agent is heated and up the temperature that can be used to vulcanize the insulation during its passage through the Chamber 13 is required.

A pump 26a is used to supply a coolant of the same nature as the vulcanizing agent

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from a heating-cooling unit 26 via a line 28 and a connection unit 29 into the chamber 14 and over to pump a line 27 back to the heating / cooling unit 26. The return line 27 for the coolant is between the connection unit 29 and the line 30 are connected to the pre-cooling chamber 14.

Behind the connection unit 29 (in the direction of the cable movement) is a return line 30a for the Liquid is provided, which is also connected to the heating / cooling unit 26. The cooling chamber 14, the lines 27, 30a and 28 are also thermally insulated and provided with heating devices. The heating-cooling unit 26 is provided with heating and cooling devices with which the cooling liquid is heated or cooled and on the Temperature can be maintained for pre-cooling the insulation during its passage through the chamber 14 is required.

The connection unit 29 is preferably of the same construction as the connection unit 21, so that the vulcanized Insulation of the cable enters the pre-cooling chamber 24 through the axial passage of the connection unit 21 and is partially cooled before it passes through an axial passage of the connection unit 29 into the chamber 15 entry. Seals between the chambers 13 and 14 are not required as the cable during its passage

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is washed around through these chambers of the same liquid that is normally in the vulcanizing chamber 13 is kept at a temperature between 200 and 300 ° C. Through the cooling device 26 is the cooling liquid in the chamber 14 is kept at a temperature in the range of 170 ° C. Since between the Both chambers do not require seals, the insulation will not come into contact with a seal subject and therefore cannot be damaged or impaired will.

The vulcanizing and precooling agent is a eutectic mixture of inorganic salts that are stable in the liquid phase over a temperature range that is necessary for the vulcanization and precooling of the elastomeric material. For example, a mixture of 53 % potassium nitrite, kO% sodium nitrate and 7 % sodium nitrate can be used.

The coated and partially cooled cable is fed from the connection unit 29 into the main cooling chamber 15 out through which a gas is circulated which does not affect the crosslinking reaction and with the insulation material not reacted. It has been found that nitrogen is a suitable means of cooling the insulation material. There is an old one for the circulation of the gas a gas cooler 32 connected pump 31 is provided. from

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the pump 21 runs a line 23 to the connector 29 adjacent end of the chamber 15 and a similar line 34 runs from the cooler 32 to that of the Connection piece 29 at the end of the chamber 15. The cooler 32 is provided with a condensate drain 35.

A connecting piece 36 is provided between the chamber 15 and the chamber 16, in which a seal is provided can be through which the now substantially cooled cable runs. Due to the meanwhile considerable As the vulcanized insulation cools down, the presence of this seal becomes the cable sheath not affect. The final cooling of the cable takes place in the chamber 16 by the Cooling liquid, preferably water, is circulated by means of a pump 37. In addition to the pump 37 are Supply and discharge lines 38 and 39, respectively, and a cooler are provided, the supply line 38 being connected to that of the connecting piece 36 distant end of the chamber 16 and the line 39 to that of the connecting piece 36 adjacent End of the chamber is connected.

In order to limit the loss of cooling liquid, is at the end of the chamber 16 at which the cable is the Device leaves, a seal 41 is provided.

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In the device described, the direction of flow is the vulcanizing and coolant opposite to the direction of travel of the cable. However, this is not absolutely necessary.

For example, the vulcanizing liquid and the cooling liquids can also be applied to the cable are sprayed on from nozzles which are arranged at intervals along the chambers 13, 14 and 16. According to a In another embodiment, the liquids can also flow in the same direction as the conveying direction of the cable. Fig. 2 shows schematically a device in which the flow direction of the cooling gas in the main cooling chamber 15 and the direction of flow of the cooling liquid in the final cooling chamber 16 in the same Direction as the direction of movement of the cable 17 are.

As can be seen from Fig. 2, the coated and partially cooled cable runs from the connection unit 29 through a short tube 46 and a connector 45 (similar to connectors 21 and 29) into the main cooling chamber 15 through which a suitable cooling gas is circulated. For the circulation of the gas there is one Pump 31 is provided, which is connected to a gas cooler 32 is. A line 33 runs from the pump 31 to the connector 45 and a similar line 34 runs from the radiator 32 to that of the connector

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45 distal end of the chamber 15. Another line 42 connects the cooler 32 with the pipe 46. The The cooler 32 is provided with a condensate drain 35.

A connecting piece 43 is provided between the chamber 15 and the chamber 16 (similar to the connecting pieces 21, 29 and 45) through which the now essentially cooled cable runs. The final cooling of the cable takes place in the chamber 16 through which the cooling liquid, preferably water, is circulated by means of a pump 37. The pump 37 is connected to a cooler 40, and a line 44 runs from the pump to the connector 43. The cooling liquid returns to the radiator via a line 38, and cooling liquid that may Has passed through the connecting piece 43 into the chamber 15, flows back to the cooler 40 via the line 39.

To limit the loss of cooling liquid, a seal 41 is provided at the end of the chamber 16, where the cable 17 leaves the device. Any losses that occur in spite of this are compensated for by a forced feed of cooling liquid into the cooler 40 via a line 46.

In deviation from the illustrated embodiments, in which a pre-cooling chamber and a final cooling chamber in front of or behind the cooling chamber charged with gas

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are arranged, the pre-cooling chamber and / or the final cooling chamber can also be omitted. Are necessary the vulcanizing cannons loaded with liquid salt 13 and the gas cooling chamber 15.

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Claims (14)

Patent claims: Process for the continuous vulcanization of elastomeric material, in particular cable coatings, characterized in that the material is passed through a vulcanizing chamber through which a stable liquid vulcanizing salζ is circulated that is kept at the required vulcanization temperature and under a predetermined pressure, and that the vulcanized material continues through a cooling chamber through which a gaseous cooling medium circulates under pressure which is of such a nature that it does not affect the crosslinking reaction and with the material not reacted. - 1 - 809851/0812 ORlGiNALlNSPECTED 2. The method according to claim 1, characterized in that the vulcanizing agent is eutectic Mixture of inorganic salts is. 3. The method according to claim 1, characterized in that the elastomeric material is before its entry into the cooling chamber charged with gaseous cooling medium through a pre-cooling chamber which is circulated under pressure a liquid coolant. 4. The method according to claim 1 or 3, characterized in that one of the supplied liquid vulcanizing agent branches off a partial flow, cools it and, after cooling, through a pre-cooling chamber circulates, which is arranged between the vulcanizing chamber and the gas-charged cooling chamber. 5. The method according to any one of claims 1 to 4, characterized in that the material after it has been cooled by the gaseous coolant, it passes through a final cooling chamber through which a liquid coolant, e.g. water, is circulated. 6. The method according to claim 1, characterized in that the material is passed through a vulcanizing chamber which contains a stable liquid vulcanizing salt under pressure that one vulcanized the 809851/081 2 MaterJäL leads through a pre-cooling chamber, the cooler one contains liquid salt under pressure, and that the precooled material by a gaseous coolant and then passes through a liquid coolant. 7. Device for performing the method according to one of claims 1 to 6 for the continuous vulcanization of elastomeric material, characterized by a vulcanizing chamber (13) with an inlet (25) and an outlet (22) for a stable liquid vulcanizing salt and with means ( 23, Zk) for circulating the liquid through the chamber (13) at the temperature and pressure required for vulcanization, and through a cooling chamber (15) connected to the outlet (21) of the vulcanizing chamber (13) with a gas cooler (32) and a Pump (31) comprising means for circulating a pressurized gaseous cooling medium through the chamber (15) which is of such a nature that it does not affect the crosslinking reaction and does not react with the insulating material. 8. The device according to claim 1, characterized by a device for pre-cooling the vulcanized Isolation under pressure before it enters the gas cooling chamber (15), the device being a cooling device (26) and an environmental pump (26a) for liquid coolant. - 3 809851/081 2 9. Apparatus according to claim 7 or 8, characterized in that in addition to the cooling chamber (15) charged with gas is provided with a cooling chamber (16) charged with liquid coolant is formed separately from the gas-charged cooling chamber (15) and at the outlet end thereof is connected and with means (40, 37) for circulating a liquid coolant, e.g. water, is provided. 10. Device according to one of claims 7 to 9, characterized in that between the vulcanizing chamber (13) and the one charged with gas Cooling chamber (15) is arranged and a pre-cooling chamber (14) to the outlet of the cooling chamber (15) one with cooling liquid chargeable final cooling chamber (16) is connected. 11. Device according to one of claims 7 to 10, characterized in that the vulcanizing chamber (13) is connected to an extruder head (12) for extruding the elastomeric material by means of a tubular connecting piece (18) which is slidably mounted in the Vulkani sierkammer (13). 12. The device according to claim 5, characterized in that on the tubular connecting piece (18) a connection (20) for the supply of gas under - 4 809851/0812 Pressure is connected. 13. Device according to one of claims 7 Ms 12, characterized in that at least the vulcanizing chamber has a chain-line shape Has. 14. The method according to any one of claims 7 to 13, characterized in that the direction of flow of the vulcanizing or coolant in the chambers (13, 14, 15, 16) is opposite to the conveying direction of the elastomeric material to be vulcanized. 809851/0812