DD246370A1 - TOUCHLESS WAY, VIBRATION CUSTOMERS WITH A STEEL LINE INDEPENDENT CHARACTERISTICS - Google Patents

Abstract

The invention "non-contact displacement, vibration sensor with a steel-type-independent characteristic" refers to the field of measurement technology and has the goal to realize an independent of the steel grade path and vibration sensor. The use of a three-coil method and an alternating zero calibration at a defined distance between the pickup head and the object to be measured - which must be determined once for the pick-up type - achieve an independence of the pick-up characteristic of the steel grade and extend the range of application of this pick-up. Non-contact displacement and vibration sensors are used in nuclear power plants, power plants, mechanical engineering, ship technology, traffic engineering, agricultural engineering, pumps and the chemical industry.

Description

Field of application of the invention

The invention relates to contactless measurement on moving parts (eg rotating shafts, vibrating machines and machine parts) and can be used in nuclear power plants, in conventional power stations, in mechanical engineering, in ship technology, in traffic engineering, in agricultural engineering, in pumps and in the chemical industry.

Characteristic of the known technical solutions

In non-contact path and vibration measurements, different object materials (steel grades) give very different characteristics depending on the steel composition. This fact limits the scope of the

strong known measuring instruments. .

According to the state of the art, the companies prescribe the steel grade for which their meter is set up. The shaft vibration measuring device "Vibro-Control 2000" from Schenk AG (FRG) is designed, for example, for the steel grade 41 Cr Mo 4 material No. 17223 according to DIN 17212.

FIG. 1 shows two characteristic curves which were recorded with different types of steel (ST 38 and 20 Mn Cr 5) with a shaft vibration measuring device according to the usual single reel principle. As can be seen, both characteristics differ considerably. In the upper ranges, the measured solutions differ by 400μηι, which corresponds to an error of about 20%.

The use of non-contact displacement, vibration sensors for only one steel grade brings with it significant disadvantages

Some companies allow the adaptation of their equipment to the desired steel grades. This requires additional work. However, this method completely fails when non-standard steels are present or the steel composition is unknown, as is often the case.

Next you can not use this Wellenschwingungsgefäte either with multiple sensors for different measuring points of different steel grades.

Object of the invention

The aim of the invention is to produce a displacement, vibration sensor that works as independently as possible.der steel grade, whereby its range is extended and accounts for individual adjustments for each type of steel. It eliminates the determination of the steel composition before use, and a Wellenschwingungsmeßgerät can be used with multiple sensors for any number of measuring points with different steels optional.

Explanation of the essence of the invention

- The invention has as its object to provide a non-contact path, vibration sensor, which has as no dependence on the steel composition. The known displacement, vibration sensors have by their working principle a characteristic which is determined by the steel composition of the test object.

- * According to the invention, this object is achieved in that a three-coil method (Figure 3) is used instead of the non-contact way, vibration measurement Einspulenverfahrens (Figure 2) and the AC balance (zero balance) is made in the preamplifier at a defined distance between the pickup and the object to be measured , to be chosen so that all steel grades have the same characteristics. This distance is to be determined once by serial measurements for a transducer type and is then fixed in all encoders of this type.

embodiment

The invention will be explained by the following example:

Instead of the usual single-coil method (FIG. 2), a three-coil method is used in which three coils are arranged on one axis (see FIG. 3) (measuring coil, transmitting coil, compensation coil). The middle transmitter coil is powered by a generator with an AC voltage. Measuring and compensation coil are switched in opposite directions, so that subtract their signals.

There is now a defined distance between the pickup head and the object to be measured for each type of such a three-coil pickup, which is characterized in that a zero balance of the alternating voltage at exactly this point, the measurement is largely independent of the steel grade.

This distance is to be determined once for a transducer type by serial measurements, and when installing a transducer of this type at its measuring location, the zero calibration of the AC voltage must be carried out once for this point. A spacer supplied by the manufacturer for each type of transducer makes this adjustment problem-free.

FIG. 4 shows the results contained for five very different steel alloys. The straight line is the curve averaged from all measurements. In the indicated intervals are all measuring points. The following steels were investigated:

1. 20 Mn Cr 5

2. 90 Mn V 8

5. unknown shaft steel

For comparison, reference is made to FIG.

Claims (1)

Invention claim: Non-contact displacement, vibration sensor with a steel-independent characteristic, characterized in that instead of the usual single-coil method, a three-coil method is used (Figure 3) and the AC zero is made precisely at the distance between the pickup and the object to be measured, in which the pickup characteristic is independent of the steel grade , For this 4 pages drawings