Abstract: A plastic welding machine, especially a hot air or hot wedge sealing machine, for connecting in a material fit at least two layers (38, 39; 43, 44; 48-50). The welding machine (1) comprises welding tools (7), at least one pair of driving rollers (8, 9) each, and an electronic control device (2) including a computer (3) for controlling the temperature of the welding tools (7) and for adjusting and regulating the pressure of the driving rollers (8, 9). A welding machine is provided wherein the welding process can be sequence-controlled substantially independently of the respective operator of the welding machine (1). For this purpose, the sequence control of the welding process is carried out without intervention of the operator only using a sequence program (welding program) stored in a memory (35) of the electronic control device (2).

Abstract: A monitor is provided for a bobbin thread on double thread lockstitch sewing machines. This is preferably a sewing machine with a rotating hook with a bobbin housing accommodating the lower thread reserve. The monitor includes a revolution sensor which sends a pulse per revolution of the main shaft of the machine to a microcomputer. An infrared laser light transmitter sends a detection beam directed toward a bobbin. The beam is reflected by the bobbin or by the roll of a residual thread length to a receiver and is sent by the latter to the microcomputer in the form of signals for processing, evaluation and/or forwarding. The microcomputer is adapted to compare the different signal patterns with a detection threshold (DS) to generate signals for controlling the sewing machine. A controllable power source is connected to the microcomputer for the occasional, stepwise reduction of the output of the infrared laser light transmitter.

Abstract: A monitor is provided for a bobbin thread on double thread lockstitch sewing machines. This is preferably a sewing machine with a rotating hook with a bobbin housing accommodating the lower thread reserve. The monitor includes a revolution sensor which sends a pulse per revolution of the main shaft of the machine to a microcomputer. An infrared laser light transmitter sends a detection beam directed toward a bobbin. The beam is reflected by the bobbin or by the roll of a residual thread length to a receiver and is sent by the latter to the microcomputer in the form of signals for processing, evaluation and/or forwarding. The microcomputer is adapted to compare the different signal patterns with a detection threshold (DS) to generate signals for controlling the sewing machine. A controllable power source is connected to the microcomputer for the occasional, stepwise reduction of the output of the infrared laser light transmitter.

Abstract: The most important heat-sealing parameters must be able to be adapted to different conditions of use in a simple and accurate manner. This is accomplished by the hot air temperature, on the one hand, and the amount of hot air, the speed of rotation of the pressing rollers (8, 9) and/or the pressing pressure of the pressing rollers (8, 9), on the other hand, being able to be controlled via controllers (41, 37, 24, 29), wherein a basic setting of the set points of these controlled variables is performed as a function of material- and/or application-specific characteristics, and by the position of the hot air nozzle (16) in terms of height (H), distance (A) and/or of the oncoming flow angle (.alpha.) with respect to the roller gap being able to be set by motor operators (18, 19, 21) as a function of the intended use and/or the thickness of the workpiece.