Abstract: A process and device for the stable width wise regulation of the bulb angle in connection with the extrusion of sheets of heat-sensitive plastic (2) in an extrusion device with a calendar opening formed by two intake rollers (3,2) and a traversing measuring device (7) provided according to the calendar slot by altering positioning elements on the extrusion device. At least two traversing measurements of a parameter correlating with the bulb angle are started consecutively on the heat-sensitive plastic sheet synchronously with the positioning of one of the two calendar rollers. Like measurement conditions therefore exist and the deviation of the measured values obtained on the basis of the measurements in relation to specified expected values is used to regulate the bulb angle over its width by altering a setting element on the extrusion device.

Abstract: A process and device for the stable widthwise regulation of the bulb angle in connection with the extrusion of sheets of heat-sensitive plastic (2) in an extrusion device with a calender opening formed by two intake rollers (3, 2) and a traversing measuring device (7) provided according to the calender slot by altering positioning elements on the extrusion device. At least two traversing measurements of a parameter correlating with the bulb angle are started consecutively on the heat-sensitive plastic sheet synchronously with the positioning of one of the two calender rollers. Like measurement conditions therefore exist and the deviation of the measured values obtained on the basis of the measurements in relation to specified expected values is used to regulate the bulb angle over its width by altering a setting element on the extrusion device.

Abstract: In the extrusion of thermoplastic deformable plastics, especially the manufacture of plastic plates, an automatic regulation apparatus on the roller discharge ensures that the extruded plastic plate is directed horizontally along the device center after leaving the roller calender. The apparatus contains a sensor unit which transmits a position signal for the horizontal position of the plastic plate to a controller which, when a deviation of the plastic plate center from the device center occurs, activates two pneumatic plug cylinders such that the plug force of the haul-off rolls changes the roller diameter and thereby guide the conveyed direction of the plastic plate.

Abstract: Extruded, smooth finished solid sheet or film, which may have a thickness<1 mm, of a thermoplastic plastic (such as polycarbonate) with a glass transition temperature >50.degree. C., which under conditions of orientation displays optical birefringence, may be manufactured into a flat strip with smooth finished surfaces, to yield a strip which has characteristics as follows:optical birefringence path difference less than or equal to 50 nm (single pass);low surface roughness;low variation in thickness;by extrusion of the plastic in a thermoplastic state, through a slot nozzle;wherein during or after the smoothing of the two surfaces one of the surfaces of the strip is cooled to below the glass transition temperature, while the other surface and the predominant part of the interior region of the strip remain in the thermoplastic state and the strip is cooled to below the glass transition temperature, under conditions which minimize the deforming forces on the surfaces of the extruded strip.

Abstract: A flat web of sizable thickness made of thermoplastic can be extruded from an extrusion die without a restrictor bar if a thickness D of a restricting passage is made smaller than a shaping distance A of die lips (4, 5), and if at least one wall of the restricting passage (6) is adjustably designed as an elastic lip (7) by adjusting elements (8), so that thickness D and distance A can be changed at the same time by actuating the adjusting elements.

Abstract: Extruded, smooth finished solid sheet or film, which may have a thickness <1 mm, comprised of a thermoplastic plastic (such as polycarbonate) with a glass transition temperature >50.degree. C., which under conditions of orientation displays optical birefringence, may be manufactured into a flat strip with smooth finished surfaces, to yield a strip which has characteristics as follows:optical birefringence path difference less than or equal to 50 nm (single pass);low surface roughness;low variation in thickness; by extrusion of the plastic in a thermoplastic state, through a slot nozzle;wherein during or after the smoothing of the two surfaces one of the surfaces of the strip is cooled to below the glass transition temperature, while the other surface and the predominant part of the interior region of the strip remain in the thermoplastic state and the strip is cooled to below the glass transition temperature, under conditions which minimize the deforming forces on the surfaces of the extruded strip.