SU142699A1 - Measuring device for determining the mutual movement of two moving parts of mechanisms - Google Patents

Description

To determine the mutual movement of the two moving parts of different machines, machines and devices, devices with a foelectric system are used in which rasters are used as measuring and indicator elements, the amount of movement of the transducers is determined by the number of light pulses generated when one lattice moves relative to another.

The light pulses are converted by photocells into voltage pulses and fed to an automatic reversing counter. The number of pulses recorded by the automatic counter determines the amount of movement. The accuracy of the displacement depends on the number of lines applied to 1 mm of raster grids. An increase in the accuracy of reference is associated with technological difficulties in increasing the frequency of raster lattices. Attempts to construct transducers with movement readings accurate to fractions of the period of the raster grid did not lead to the desired results.

Known pulse-phase systems with signal modulation depend on the magnitude of the luminous flux and on the magnitude of the voltage supplying the photocell, they are not sensitive enough to provide the required measurement accuracy. The modulation of the luminous flux with the help of shutter disks and dampers is cumbersome and unreliable. The accuracy of converters of this type is also low.

The proposed measuring device for determining the mutual displacement of two moving parts of mechanisms, in contrast to the known, has a higher sensitivity and measurement accuracy. This is achieved by the fact that the indicator raster of the device is softened relative to the measuring device by means of an electromagnetic system, and also oscillates in the plane of the rasters, which ensures the scanning of the light bands relative to the slits of the diaphragm located in front of the photocell.

№ 1426992

FIG. 1 is a schematic diagram of the device described; on fi. 2 shows the dependence of the photocurrent in the relative movement of rasters within one step T.

The device uses a scanning modulation method that provides simplicity, reliability, and a large relative modulation factor of the light flux.

The device consists of an illumination unit /.with oscillating rhythm with a raster, which transforms raster grid 2 and a photo of cell 3 with a photocell.

The illuminator assembly contains an incandescent bulb or a gas-light lamp 4 in front of which frame raster 6 is fixed on frame 5. Frame 5 is vibrated under the action of an alternating magnetic field created by the aid of an electromagnet 7, the winding of which is powered by an alternating current.

The converting raster grid 2 and indicator 6 are glass rulers with bright and tempo lines applied to them. The width of the light lines is approximately equal (dark pirine.

The photo cap 3 is made in the form of an opaque body, inside of which a photocell 8 is placed. In front of the photocell there is a screen with aperture 9.

The transforming and indicator grids, the photocell and the illuminator are arranged in such a way that the moire strips resulting from the darkening of the bright lines of one of the rasters by the dark lines of the other raster enter the screen and change the light flux passing through the aperture of the photocell. Moving one raster relative to another one step corresponds to a full cycle of changing the luminous flux passing through the aperture slits, i.e., a full cycle of changing the photocurrent in a photocell.

FIG. 2 shows the dependence of the photocurrent with relative movement of rasters within one step of 7 moire bands.

T: -. ,

where t is the raster step;

F is the angle of intersection of the lines of both rasters.

If the moving lanes are taken as moving lanes and

the shadow of a raster optical vernier, then 7 t, where C is the distance between the thread of the light source and the photo cell screen; L is the distance between the rasters.

Works measuring device as follows.

When the lattice oscillates, the moire strips or stripes of a raster optical vernier oscillate relative to the light slits of the photocell screen. If the light strips oscillate symmetrically with respect to the lines passing through the symmetry axes of the light gaps in the diaphragm or in the middle of the gaps between the slits, then the photocurrent frequency in the photocell doubles compared to the frame oscillation frequency (see Fig. 2). If the oscillation range is laid on the linear part of the light characteristic of the raster system, then the current in the photocell has a sinusoidal pattern of the same frequency as the frame oscillation. When the strips are moved relative to the slits by a half step, the phase of the current in the photocell changes by 180 °. The voltage applied from the load of the photocell to the phase-sensitive measuring instrument, the reference voltage in which has the same frequency as the oscillation frequency of the frame, is measured