High-accuracy spring-type dial indicator

Conclusions

• 1. The creation of an industrial model of an instrument in accordance with the described scheme practically solves the problem of increasing the accuracy of spring-type dial indicators up to values satisfying class 0.1 of GOST 11606-65 with a reserve accuracy of 0.03–0.04%, which is sufficient for compensation of the errors occurfing due to imperfection of the lever system, and the attainment of the scales in the set of accuracy corresponding to class 0.1 per GOST 13712-68. This significantly extends the field of application of spring-type dial indicators.

• 2. The solution of this problem is provided by simple design means, which is an advantage of the described instrument in comparison with existing models. This instrument incorporates a spring-type force meter stiffness regulator, with the aid of which the indicator is adjusted using a simple method widely used in instruments of various accuracies. All this ensures minimum expenditure of labor in manufacturing the instrument and ensures its being competitive.

• 3. In this instrument it is not possible to attain the accuracy of quadrant dial indicators, i. e., 0.05% of the greatest measurement limit. Such accuracy, in our opinion, is practicallyunattainable in spring-type dial indicators due to the impossibility of significant reduction of elastic imperfections of the spring-type force meter when manufacturing springs using economically acceptable methods.

• 4. The problem of creating an instrument of class 0.1, as required by GOST 11606-65, is reduced to providing a basic allowable error corresponding to this class, i. e., obtained under normal test conditions [11]. So far as the reduction of additional errors arising due to changes of temperature and other external factors in the instrument's operating environment are concerned, the problem is no less (if not more) complex and is the subject of independent investigations [3].

• 5. An economically desirable means for further increase of the accuracy of spring-type dial indicators is improvement of the supports of axles, in particular the use of miniature ball bearings without an internal ring, or supports kinematically connected to the deformed force meter and transmitting the rotary motion bearing on their axles.