電話器用Gongの固有振動数の異方性について

Abstract

To obtain a gong having only one natural frequency for use for telephone, we studied the directional properties of the natural frequency of gongs of 65/35 and 60/40 brass, as well as their directional property in case they are made by deep drawing, with the following results:1. Generally speaking, the natural frequencies in 0° direction (the direction, in which the material brass plate is rolled) and in 90° direction (the direction at right angles with 0° direction) of a gong are one and the same; and its natural frequency in 45° direction always is constant. But those in 0° and 90° directions and that in 45° direction are not the same.2. We succeeded in making a gong having no directional property of its natural frequency from 65/35 drass, but failed in so doing from 60/40 drass.3. We ascertained that there is no direct relationship between a change in the properties in 0° and 45° directions due to the ratio of the thickness of cold-rolled material brass plate and temperature, at which it is annealed, and a change in these properties due to drawing.4. The conditions most suitable for the manufacture of a brass gong having no directional property of its natural frequency are as follows: 3& (1) Composition: & 65/35 Brass & (2) Ratio of cold-rolling reduction of thickness: & 30% & (3) Annealing temperature: & 400 ∼500°