Patent GB-1405891-A (GB)
Title: Apparatus for producing carbon fibres
IPC: F27D11/04
Filed: 1971-06-28
Abstract: 1405891 Carbon fibres QUIMCO GmbH 28 June 1972 [28 June 1971] 30213/71 Heading C1A [Also in Division F4]  Carbon fibres are continuously manufactured by first oxidizing at least one band of continuous fibres by moving them through a chamber through which an oxidizing gas is passed, the band of fibres being arranged within the chamber so that the gas flows through the band at a velocity less than that at. which it flows through the chamber and then moving the band through an inert atmosphere in which the fibres are carbonized and then cooled to a temperature below that at which they are oxidized before being again exposed to an oxidizing atmosphere. The carbonization temperature may be in the range 1500 to 3000‹ C. and the fibre is cooled to 100‹ C. or less before further exposure to an oxidizing atmosphere. Polyacrylonitrile is the preferred fibre material. An apparatus shown in Fig. 1 for such continuous manufacture of carbon fibres comprises a first housing 40, and second housing 56, the exits and entrances of both housings being fitted with sealing means 100 which permits the passage of at least one band of fibres therethrough but which otherwise substantially seals the housings, means, e.g. roller assemblies 12, 13 and 25 being provided entirely externally of the housings to move the fibres at controlled, preselected speeds and tensions. Detail of the oxidation chamber which occupies housing 40 is shown in Fig. 2, it may have a partition 43 dividing it into upper and lower levels 41, 42, the partition being divided by gap 44 into two identical halves, the oxidizing gas, e.g. air, being introduced into the lower level and passing through the gap into the upper level, where it is drawn along by fans 49 and at least part of it recirculated after purification if required, make up air being introduced if necessary. The air is heated by elements 48 and passes through the band of fibre by virtue of the guides 53, 55 in the upper section. In entering the chamber, the band of fibres pass through the seal and into a slit 45 which is of a length sufficient to protect the seal from the heat. The housing 56 contains a carbonizing chamber and downstream thereof a cooling section 69. The carbonizing chamber may be divided into an upper portion 57 and lower portion 58. Heating elements 62, e.g. of graphite yarn are arranged in an inert atmos. in port 58 to produce a given temperature distribution, and graphite rods 68 are arranged to support the fibre band in the upper section. An inlet (Fig. 9, not shown) is provided to introduce inert gas into the chamber, a suitable outlet also being provided. In use, a number of fibre tows are drawn from bins 11, formed into at least one flat band in creel arrangement 26, and passed through the oxidizing carbonizing and cooling section by means of roller arrangements 12, 13 and 25 before being wound on to take up units 26a. Between housings 40 and 56, among the rolls 13, there is positioned a unit 105 which functions as a fibre storage device, the roller 90 being movable back and forth under the oven for example from the position shown in full line in Fig. 1 to that shown dotted, so as to create a longer path for the fibre and thus an effective store. The movable roll 90 permits feed rates through the oven and the furnace to be different from each other, since its movement to left or right effectively slows down or speeds up the feed to the furnace.