Abstract: An improved continuous automated method of manufacturing insulated door panels is provided. The process includes a step of continuously connecting discrete first skin segments end to end by means of flexible joints to form a string of first skin segments and then conveying the string to a foamable liquid injecting station. In a preferred embodiment, a polyethylene film is applied to the string in order to contain foamable liquid in event of a gap caused by separation of a flexible joint.

Abstract: Obstruction detector apparatus operatively coupled to an automatic electric door operator compares the time span of transmission and receipt of reflected echoes of ultrasonic energy within a door passageway obstruction zone with predetermined time spans in order to prevent door closure under conditions indicating passageway obstruction or system malfunction. Signal generators provide timing signals respectively representative of the anticipated time span of reflected echoes from locations in front of, and beyond, the door jamb opposite the ultrasonic transmitter and receiver transducers for comparison by a relay controller with the time of generation of a signal representing a reflected echo at the transducer receiver, the relay controller appropriately actuating a door operator relay in response to such comparison.