SU1392342A1 - Measuring head - Google Patents

Abstract

The invention relates to a measurement technique and can be used, for example, in coordinate measurement maps when monitoring complex surfaces. The aim of the invention is to expand the functionality. The signals supplied to the A-A excitation electrode 7 from the generator 13 high-frequency oscillations, excite resonant oscillations in the exciter, which are transmitted to the measured. telny tip. In case the measuring tip does not touch the product under test, the signal at the output of the phase meter 14 is zero. When the tip of the monitored product is touched, a touch-fixing signal appears at the output of the phase meter 14, due to the fact that the signal from electrode 8 will be out of phase with respect to the signal from oscillator 13. Simultaneously from the output of the adder 15, a signal appears that is proportional to the strength of the product's reaction along the OZ axis. The signals at the outputs of the adders 16, 17 are proportional to the respective components of the projections of the reaction forces from, PS and its OS is 1 to 5 From 15

Description

divide by the X and Y axes. The inputs to the sum-TJopOB 16, 17 signals come from electrodes 9-12. In the registrar 18

The coordinates of the contact point Z, X, Y are calculated according to the increased signals. 2 Ip.

one

The invention relates to a measuring technique and can be used, for example, in coordinate and imaging machines for controlling complex surfaces.

I The purpose of the invention is to expand the functional capabilities of the measuring head by ensuring the possibility of obtaining information about the magnitude and direction of the vector from the point of contact to the center of the measuring tip.

Figure 1 shows the measuring head, front view; Fig. 2 shows sections A-A, B-B and B-B in Fig. 1 (a piezoceramic rod and a block diagram for connecting measuring units).

The measuring head (Fig. 1) includes a housing 1, a holder 2, which is connected to the housing by means of an end gear, the axial tension of which is provided by a spring 3. A piezoceramic cylindrical rod 4 with a measuring tip 5 is attached to the holder. 6 piezoceramic rod (Fig. 2) is grounded and made in the form of wire, the axis of which coincides with the longitudinal axis of the rod, and the length is equal to the length of the rod. The outer electrode is divided into exciting 7 and measuring 8 - 12 electrodes. The exciting electrode 7 is connected to a high-frequency generator 13 of electrical oscillations. The measuring electrode 8 is connected to the inputs of the phase meter 14 and the adder 15, to the other input of which the output of the high-frequency generator 13 of electrical oscillations is connected. The measuring electrodes 9 and 11 are connected to the inputs of the adder 16, and the measuring electrodes 10 and 11 are connected to the inputs of the adder 1 7. The outputs of all three adders and the phase meter are connected to the recorder 18, like a computer of the coordinate measuring machine.

Adders 15-17 are used to measure the difference in amplitudes of the two electrical signals.

Measuring head working

5 as follows.

A high-frequency voltage is applied to the exciting electrode 7 of the generator 13, under the action of which resonant longitudinal oscillations are excited in a piezoelectric exciter. Due to the direct piezoelectric effect in the measuring electrodes 8-12, electric charges of the same frequency are excited.

5 The amplitudes of oscillations in these electrodes depend on the force with which the tip acts on the surface. If the tip does not touch the surface, then due to the symmetry

The 20 electrodes 9-12 at the outputs of the adders 16 and 17 will have a zero signal, and the code of the adder 15 will set to zero.

The frequency of the generator is chosen close to the main (first) form of natural oscillations of the measuring head. Due to the high quality factor of the oscillatory system of the measuring lever, the phase shift between oscillations and

The power supply voltage is negligible. As a result, on the code. In phase 14, the voltage will be zero if the measuring tip does not touch the object being monitored.

five

At the moment of touching the measuring

the tip of the object being monitored, the quality factor of the oscillatory system is sharply reduced, as a result

0, the phase shift between the supply voltage and the oscillation increases, which is recorded by the phase meter 14 and the computer. The direction of the normal. From the point of contact of the measuring lever

The g with the measured surface is the direction of the force with which the measuring head puts pressure on the surface, or the direction opposite to the reaction force.

The force vector (Fig. 1) is decomposed into its component parts:

Fx

.one

 i + F ,, - + F. -k,

and it are the unit vectors parallel to the axes Ox and 0, respectively, F, iF and F

but;

2 - the magnitude of the projections of the force F reaction on the axis

ABOUT

X

Oj and og

respectively.

The oscillations after tangency occur in a plane passing through the axis Oj and the point of tangency. Since the electrode 8 is solid, the voltage on it

proportional only to the linear color of the high-frequency oscillations, the system re- bar along the axis 0. The magnitude of the voltage amplitude on the electrode 8 is greater, the smaller the force component FJ, i.e.

A histor connected to the output of the latter, characterized in that, in order to expand the functionality of the head by providing the possibility of obtaining information about the magnitude and direction of the vector from the touch point to the center of the measuring tip, the head is equipped with three adders, the piezoelectric mechanical oscillator is made in a piezoelectric cylindrical rod with a radial polarization, an internal electrode placed along the axis of the rod, and an external electrode placed on the surface The internal rod is grounded, the outer electrode is divided into three insulated one from another, the lower and middle parts are rings, the upper part is divided into four symmetric ring segments isolated from each other, the lower part is the exciting electrode and connected to the first one the input of the first adder, the middle part to the second inputs of the phase meter and the first adder, diametrically opposite segments of the upper part to the first and second inputs correspond to | Ug | | U, ol - 1-F

X

IUg I is the amplitude of voltage fluctuations on the electrode 8; lUj, is the voltage oscillation amplitude at the electrodes 8-12 in the absence of contact; 1 - proportionality coefficient.

Thus, at the output of sum 5, we get the signal

lu.oi - 1and „1,

I-fz - 6

proportional to fj.

The difference in voltage amplitudes on electrodes 9 and 11 is proportional to the moment of rod bending acting in the ZOX plane, i.e. F. In turn, the difference in voltage amplitudes on electrodes 10 and 12 is proportional to the moment of rod bending acting in the ZOY plane, i.e. component F ,,.

Thus, from adders 15-17, signals are received on the computer that are proportional to the components F

35

40

45

2

X

A histor connected to the output of the latter, characterized in that, in order to expand the functionality of the head by providing the possibility of obtaining information about the magnitude and direction of the vector from the touch point to the center of the measuring tip, the head is equipped with three adders, the piezoelectric mechanical oscillator is made in a piezoelectric cylindrical rod with a radial polarization, an internal electrode placed along the axis of the rod, and an external electrode placed on the surface The internal rod is grounded, the outer electrode is divided into three insulated one from another, the lower and middle parts are rings, the upper part is divided into four symmetric ring segments isolated from each other, the lower part is the exciting electrode and connected to the first one the input of the first adder, the middle part to the second inputs of the phase meter and the first adder, diametrically opposite segments of the upper part to the first and second inputs of the corresponding reaction forces, respectively. Coordinately with the second and third adders, the nats of the touch point are calculated and the outputs of the adders are connected to the corresponding computers by signals from the adders,

The contact point coordinates find the computer by counting from the center of the measuring tip against the direction of the reaction force of the tip radius.

Claims (1)

Invention Formula A measuring head containing a measuring lever with a measuring tip, kinematically associated with it a piezoelectric exciter of mechanical oscillations, a generator of high-frequency oscillations, connected to the excitatory electrodes of a piezoelectric exciter of mechanical oscillations, a phase meter connected by one of the inputs to the output of the generator5 0 five 0 five A histor connected to the output of the latter, characterized in that, in order to expand the functionality of the head by providing the possibility of obtaining information about the magnitude and direction of the vector from the touch point to the center of the measuring tip, the head is equipped with three adders, the piezoelectric mechanical oscillator is made in a piezoelectric cylindrical rod with a radial polarization, an internal electrode placed along the axis of the rod, and an external electrode placed on the surface The internal rod is grounded, the outer electrode is divided into three insulated one from another, the lower and middle parts are rings, the upper part is divided into four symmetric ring segments isolated from each other, the lower part is the exciting electrode and connected to the first one the input of the first adder, the middle part to the second inputs of the phase meter and the first adder, the diametrically opposite segments of the upper part to the first and second inputs corresponding to the inputs register torus. Fi 1