What is claimed is:
1. An extruder for processing a rubber mixture, comprising:
a cylinder;
a screw rotatably supported in the cylinder for uptake, transport, mixing and extruding a rubber mixture; and
a head with incorporated extrusion tool,
wherein the screw is so defined by a helix angle and a thread depth as to have an entry zone in which the rubber mixture is exposed to an increased pressure, and an exit zone in which the rubber mixture is exposed to a constant or decreasing pressure, so that the rubber mixture is subjected to a temperature rise during its advance to the extrusion tool as a consequence of heat dissipation to thereby realize an extrudate at a temperature which approximates a vulcanizing temperature for the extrudate.
2. The extruder of claim 1, wherein the screw is a multithread screw, with the number of threads increasing as a diameter of the screw increases.
3. The extruder of claim 1, wherein the screw in the exit zone is configured as a screw of minimum output with a small helix angle .
4. The extruder of claim 3, wherein the helix angle in the exit zone is about 7-14.
5. The extruder of claim 1, wherein the screw has in the exit zone a thread depth which is smaller than a thread depth in the entry zone.
6. The extruder of claim 5, wherein the thread depth in the exit zone is less than 0.15 a diameter of the screw.
7. The extruder of claim 1, and further comprising an insulation ring, wherein the cylinder includes at least two subassemblies which are separated from each other by the insulation ring to thermal de-coupling of the subassemblies.
8. The extruder of claim 1, and further comprising a pressure piece inserted in the head for reducing a free volume and, optional pressure increase.
9. A method for processing a rubber mixture in a screw extruder for production of elastomeric products, comprising the steps of:
feeding the rubber mixture to an extruder for plastisizing and shaping into a desired extrudate for subsequent exposure to a vulcanizing process, wherein the rubber mixture is advanced in the extruder by a screw from a screw entry zone under increasing pressure in a direction of a screw exit zone in which the rubber mixture is advanced at a constant or decreasing pressure, wherein a helix angle and a depth of thread of the screw are selected in such a way that a cylinder exit zone is overshot by a cylinder entry zone to continuously increase the temperature of the rubber mixture; so that the extrudate exits the extruder at a temperature which approximates a vulcanizing temperature of the extrudate.
10. The method of claim 9, and further comprising the step of increasing the screw speed to increase the temperature of the rubber mixture while retaining a low output of extrudate.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An infrared gas detector for detecting a density of a sample gas comprising:
a pedestal;
a cap disposed on the pedestal, the cap including a window and a filter disposed in the window for selectively passing a specific wavelength of infrared light;
an infrared light sensor disposed on the pedestal and within a cap, wherein the infrared light sensor is configured to output a first signal corresponding to a density of the sample gas under the influence of water vapor based upon based upon an intensity of the infrared light received at the infrared light sensor via the filter;
a humidity sensor disposed on the pedestal and outside of the cap, the humidity sensor configured to output a second signal corresponding to an absolute humidity of the water vapor in the sample gas based on an intensity of infrared light received at the humidity sensor; and
a processor configured to determine the density of the sample gas by correcting the detected density of the sample gas under the influence of water vapor based upon the detected absolute humidity.