| 摘要 |
PURPOSE: To prevent measuring errors caused by the surface defect of a chip or the like by measuring the weight of an object using a robot device in a dry medium and in a wet medium, and calculating the density of the object according to Archimedes' principle. CONSTITUTION: Air, for example, is used as a dry medium, and distilled water of a known temperature and density as a wet medium. A pellet 1 (object for measurement) on a conveyor 2 is taken out by the fingers 27 of a robot 21 for extracting and placing and is placed on a dry measuring saucer 17 to measure the weight W1 of the pellet 1 in air with a balance. Next, after the pellet 1 is temporarily placed on a plate 31, it is put into water in a tank 7 by the fingers 29 and placed on a wet measuring saucer 19 to measure the underwater weight W2 of the pellet 1. The measurements are input to a CPU, where the density D of the pellet 1 is calculated according to Archimedes' principle using D=(W1×d)/(W1 -W2 ). In the formula, (d) is the density of the water.
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