ECCENTRICITY MEASURING INSTRUMENT FOR EXTRUDER

PURPOSE:To obtain an eccentricity measuring instrument having the easy maintainability and the high measuring accuracy by receiving light beams in parallel to the stem axis with photodetector on the external surface of a container and calculating an eccentric amount based on detection signals from the photodetectors. CONSTITUTION:A stem 2 is advanced to be inserted into a container 1. Laser oscillator 3a and 3b irradiate light beams to photodetectors 4a and 4b and photocurrents are taken out from electric poles on the top, bottom, right, and left points of the light receiving surface of the photodetectors 4a and 4b. An computing element 5 amplifies the respective currents from the top and bottom points of the surface and calculates deviation amount of the light receiving point. The calculated value is recorded in a recorder 6 and is indicated in an indicator 7. Therefore the deviation amount from the center is obtained by detection of the photocurrents.