GB1276101A - Improvements in or relating to the manufacture of electric heating panels - Google Patents

Abstract

1276101 Moulding electric heating panels CAPE ASBESTOS INSULATIONS (PTY) Ltd 26 Aug 1969 [6 Sept 1968] 42635/68 Heading B5A [Also in Division H5] A heating panel is manufactured by locating a heating element in a mould, passing a slurry of asbestos and binder into the mould, and withdrawing excess liquid through the base of the mould to leave an asbestos-binder mat in which the heating element is encased. The mould apparatus comprises two moulds 11, only one being shown, adapted for alternate operation. In one embodiment of the invention a nickel chrome multistrand or single strand wire is wound about pins 18 projecting from longitudinal side members of a frame 16 to form a zigzag heating element. The frame 16 may be releasably secured to the mould 11 and as described is pivoted thereto to enable it to be swung between the vertical and horizontal. With the frame vertical, a fixed quantity of slurry which consists of amosite and portland cement in water or asbestos in a synthetic resinous material, is introduced into the mould which has side walls 12 and a perforated base 13. Air is then evacuated from sump 15 causing excess liquid to be drawn off through the base 13 of the mould. The frame 16 is then swung to the horizontal position to place the element just above the asbestos-binder mat so formed. A second measured charge of the slurry is then fed to the mould to embed the heating element and the excess liquid is once more draw off through the base of the mould. One side of the frame 16 which is pivoted relative to the remainder is then relatively pivoted to release the tension on the heating element, and the frame is then swung to the vertical leaving the element embedded. The mat so formed is then stripped from the mould by supplying air to the perforated base 13 and the base is then raised by an hydraulic lift 14 to permit easy handling of the mat. The mat is then placed between galvanized plates in turn sandwiched between two composite boards and inserted in a press to remove the bulk of the moisture. The mat is stored for four days between the plates for partial curing, or is stripped from the plates, trimmed and stored for ten days in humid conditions to complete curing and is finally oven dried to form a rigid panel. The panels may be provided with feet or may be adapted for mounting on a wall. The method may be modified by placing a performed asbestos-cement mat in the mould and then embedding the superposed heating element in a further asbestos-cement mat as previously described. Alternatively, the heating element may be inserted initially into the mould and then embedded in asbestos-cement slurry in a single operation.