Basf Aktiengesellschaft

Karl H Scholl

Karl Hagen

Gerhard Grimm

Gerhard Schmelzer

Moldings, for example hollow articles, are produced by sintering a thermoplastic powder or granular material and then reshaping the resulting blank by thermoforming. Sintering is carried out in a mold cavity under pressure, by exposure to high-frequency vibrations, which heats the plastic to a temperature intermediate between its softening point and its melting point. In this way, grain boundary adhesion between the individual plastic particles constituting the blank results, and the directly subsequent thermoforming can be carried out without additional supply of heat.

Manufacture of a molding from a thermoplastic powder or granular material

In an apparatus for heating preshapes consisting of a thermoplastic, in particular a fiber-reinforced plastic, the preshape is fed, by a conveyor belt, to a heating apparatus equipped with bright infra-red radiators. To provide time-dependent metering of the thermal energy, the installation possesses an electronic control unit, equipped with a microprocessor, which unit generates a periodically increasing and decreasing electrical signal voltage, whose time-curve and amplitude can be varied in accordance with the heat uptake capacity of the preshape. The signal voltage additionally controls a feed unit, which in turn feeds to the heating apparatus, by means of a phase control system, a periodic electric current which in its time-curve and amplitude corresponds to the pre-programmed signal voltage.

Apparatus for heating sheet-like thermoplastic preshapes

A process for the manufacture of wires and profiles, wherein thermoplastics are first mixed, in the melt, with from 5 to 40 per cent by weight (based on the mixture) of aluminum needles of length from 0.3 to 6 mm, of average diameter from 0.02 to 0.1 mm and of length to average diameter ratio of from 3 to 100, the mixture is extruded to give a wire or profile in which the aluminum needles are substantially oriented axially, and this wire or profile is finally hardened by cold-working.

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Lambsheim, Germany

Karl H Scholl