Abstract 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.
An arrangement for heating sheet-like preshapes consisting of a thermoplastic, especially of a fiber-reinforced thermoplastic, said arrangement comprising an infra-red heating apparatus equipped with bright infra-red radiators, a conveyor belt feeding the preshapes to said apparatus, an electronic control unit provided with a microprocessor, said control unit generating a periodically increasing and decreasing electrical signal voltage, whose time-curve and amplitude are variable in accordance with the heat uptake capacity of the preshapes, and a feed unit controlled by the signal voltage, said feed unit having phase-controlled rectifier means for in turn metering to the heating apparatus, a periodic electrical current which in its time-curve and amplitude corresponds to the preprogrammed signal voltage.
Claim 2
Dependent Claim
112 words
An arrangement for heating sheet-like preshapes consisting of a thermoplastic, especially of a fiber-reinforced thermoplastic, said arrangement comprising an infra-red heating apparatus equipped with bright infra-red radiators, a conveyor belt feeding the preshapes to said apparatus, an electronic control unit provided with a microprocessor, said control unit generating a periodically increasing and decreasing electrical signal voltage, whose time-curve and amplitude are variable in accordance with the heat uptake capacity of the preshapes, and a feed unit controlled by the signal voltage, said feed unit having phase-controlled rectifier means for in turn metering to the heating apparatus, a periodic electrical current which in its time-curve and amplitude corresponds to the preprogrammed signal voltage.
Claim 3
Dependent Claim
25 words
An arrangement as claimed in claim 1, which also comprises a temperature-regulating unit which is interactively connected to the heating apparatus and the feed unit.
Claim 4
Dependent Claim
37 words
An arrangement as claimed in claim 1 or 2, wherein the heating apparatus possesses a plurality of heating zones arranged in the direction of travel of the conveyor belt and switchable in sequence by the control unit.
Claim 5
Dependent Claim
32 words
An arrangement as claimed in claim 1, wherein the control unit is adapted to vary the speed of travel of the conveyor belt as a function of the metering of thermal energy.