Patent GB-1219144-A (GB)
Title: Manufacture of porous bodies
IPC: D21J5/00
Filed: 1968-04-17
Abstract: 1,219,144. Moulding pulp. A.M.F. CORP. 17 April, 1968 [15 May, 1967], No. 18091/68. Heading B5A. [Also in Division B1] Fibrous articles, e.g. tubular filters, cups, hats, radio speakers or rectangular boxes, are moulded by the suction deposition thereof from a water or alcohol slurry on to one or more foraminous formers 44 in an accretion tank 52, 36 which is selectively supplied with predetermined amounts of different slurries, e.g. A, B or C, and with the slurry liquid, whereby the composition of the article may selectively be varied throughout the thickness thereof and the former is submerged until all the slurry supplied to the tank 52, 36 is exhausted. Each slurry A, B or C is fed through valves to respective metering tanks 16a, 20, 16b provided with agitating means 34 &c. and vertically adjustable slurry level sensors 84, 86 and 118. Water level sensors 78, 80, 112 are provided to maintain the water in each tank 16a, 20, 16b, as admitted through valves 74, 76, 110, at a correct level during selective slurry discharge therefrom, during moulding, to the accretion tank 52, 36 which is also provided with similar sensors 82, 88, respectively for water and slurry, and a water inlet valve 72. The sensors may give a signal for manual operation of the respective inlet valves or may actuate poweroperating means therefor. Metering tanks 16a, 16b are provided with respective discharge outlets 22, 22a to tank 20 respectively selectivelycontrollable through shut-off valves 24, 24c and adjustable flow regulators 25, 25c, whereby the relative proportions of slurries A and C may selectively be varied in the slurry mixture which is discharged from tank 20, through shut-off and regulating valves 24<SP>1</SP>, 25<SP>1</SP>, to the accretion tank 52, 36. The metering tanks 16a, 16b are also provided with valves discharge outlets 92, 92a to the accretion tank 52, 36 which by pass metering tank 20 whereby zones throughout the thickness of the article may selectively be deposited from a single slurry. The discharge outlets 92, 92a are supplied either via stand pipes 94, 94a, the entry whereto is controlled by vertically adjustable sleeves 100, 100a, or by valves 96, 96a. The accretion tank comprises a cylindrical wall 52 removably sealingly disposed around a base 36 located over a drainage basin 38 and is supplied with slurry from a manifold 56, via openings 60 around the wall 52. The foraminous mandrel 44 for a filter cartridge is provided with a lower, 46, and an upper flange 48 defining the cartridge thickness and is mounted on an outlet to a suction pump, controlled by a valve 42<SP>1</SP>, and is surrounded by a cylindrical baffle 64 connected to the wall 52. The moulding operation is commenced with the mandrel 44 immersed in slurry free fluid admitted through valve 72 and the mandrel 44 remains immersed throughout the moulding operation until residual liquid is discharged through drain valve 31 whereafter wall 52 with baffle 64 are raised, and flange 48 removed to permit removal of the filter cartridge. Alternatively, the mandrel 44 may be raised from the accretion tank 52, 36 before drainage thereof. The manufacture of various cartridge filters is described, Figs. 3-7, not shown (see, Division B1), which may be produced with different zones throughout the thickness thereof being formed from different slurries and/or varying proportions of mixtures of two slurries. In a simplification of the apparatus, Fig. 1, not shown, a slurry B is supplied directly to a metering tank (20) to which a further slurry A is suppliable, via a metering tank (16). The cartridge may be resin impregnated from the fibrous slurry, or may subsequently be impregnated with phenolic resin. The moulding of a hemispherical bowl is also described comprising high phenolic resin content outer layers enclosing a low phenolic resin content inner layer, the slurries being sequentially fed into the accreting tank, via a circular baffle located vertically above the mould. The bowl preform produced was ejected from the mould by compressed air, dried in an oven, and then pressure moulded at 800 p.s.i. at 300 F. for 5 minutes. The moulding of a plenum chamber for a car heating system from two slurries is also described, wherein a moulded preform is dried under pressure between heated vented dies prior to varnish impregnation by dipping and baking.