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The steel ball shakes the design of the electric system of the measuring apparatus

27th September 2010 Bearing Technology 0 Comments

Summary: The electric system introducing the steel ball and shaking the measuring apparatus designs, adopt integrated state variable wave filter, integrated real virtual value, logarithm converter and integrated function generator,etc. and integrate the device, make the measurement of its electric measuring system tall in precision, it is stable and reliable to work.

Keyword: Steel ball; Shake the tester; Integrated circuit; State variable; Wave filter

With the development of microelectric technique, a lot of powerful IC chips have appeared, these chips can often integrate the circuit of an intact function on a chip, or integrate the circuit even a whole set of observing and controlling circuit of several relevant functions on a chip. In the development of the modern instrument, should adopt the integrated device as much as possible. The electric system that the steel ball shakes the measuring apparatus designs, has fully adopted the chip of the high integrated level to simplify the circuit or circuit to design, have utilized the integrated state variable wave filter; Integrated real virtual value, logarithm converter; Integrated function generator,etc., has raised the performance of the electric system of the instrument, has lowered costs.

A operation principle

The steel ball examined is fixed and rotated on the high-accuracy main shaft through different fetus, the acceleration sensor is contacted with the surface of steel ball examined, and pick up the faint vibration signals of the surface of the steel ball caused by and the ripple. After this signal is amplified by the electric charge amplifier, through 170- 400Hz or 400- 800Hz band-pass filter, send to virtual value, logarithm circuit, indicated finally the ripple shaking value which examines the steel ball, the size of its shaking value uses one decibel of value tolerance by the gauge outfit. There is this instrument from the circuit of the school, its circuit produces 260Hz and 520Hz sinusoidal wave signal, is used for regulating at any time. The principle of measurement of the electric system is shown as in Fig. 1.

Design of the circuit of main unit 2

2.1 Leading to enlarge the circuit

The steel ball shakes the collecting and shaking device of the measuring apparatus as the piezoelectricity type acceleration type sensor. There are 3 kinds of structure forms of this kind of sensor: Perimeter compressing type, the centre compressing type and shearing type. Consider from performance and economic view, select the compressing sensor of Model YD-12 centre for use. Piezoelectricity slice and quality piece of this type sensor are isolated from outer cover, error and horizontal sensitivity caused to the base emergency are relatively small, than resisting the environment and interfering with ability strongly of perimeter compressing sensor.

There are two kinds of forms in the pre-amplifier circuit of the circuit of measurement related to piezo-electric component: First, the voltage amplifier feedbacked with the resistance, the voltage of its output and inputting the voltage namely the output of the sensor Directly proportional to; Another kind is the electric charge amplifier taking the electric capacity to feedback, the voltage of its output is directly proportional to with importing the electric charge. The voltage amplifier compares with electric charge amplifier, the circuit is simple, but apt to be influenced by external interference, and the cable distribution capacity measures the precision and exerts a tremendous influence to the sensor, but the distribution capacitance of the cable relates to wire kind and length, if change the cable, must adjust one time of rate of the pre-amplifier again in measuring; The output voltage of the electric charge amplifier is proportional to electric charge amount of the sensor, the influence changed to the cable length can nearly ignore, so adopt the electric charge amplifier to amplify the circuit in this measuring system as being leading. The electric charge amplifier is that a high electric capacity that gains feedbacks the amplifier, its basic circuit is shown as in Fig. 2, in the dotted line frame is the equivalent electrical circuit of the sensor.

Output amplitude

In the type

Q – sensor electric charge amount

C a – sensor capacitance

Hindering value of R a – sensor

C f – electric charge amplifier feedbacks the electric capacity

R f – electric charge amplifier feedbacks the resistance

The gaining of A – operation amplifier

The output voltage depends on Q and C f. In order to receive the essential measurement precision, require temperature and time stability of C f to be on good terms.

A characteristic frequently

Act as

In the type

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