SU1656309A1 - Automatic strain-measuring device - Google Patents

Description

t

(21) 4659764/28

(22) 12.30.88

(46) 06/15/91, Bull. Nf 22

(71) Moscow Scientific Production Association Measuring Instrument

(72) V.R.Santo (53) 531.781.2 (088.8)

(56) Universal testing machines of the company UGS. Avenue.

(54) AUTOMATIC TENSION METER

(57) The automatic tensometer is related to the measurement technique and is intended to measure the relative deformation of the samples of materials in the test machine. The purpose of the invention is to increase reliability and accuracy. The goal is achieved by the fact that the automatic tensometer is equipped with a micrometer screw 1, on which half of the carriages 2 and 3 are strung like a door hinge by means of a bracket 4. The bars 5 are pressed to the nut 6 with the toothed crown, and the carrier 7 rotates the nut 8, which serves as a support for the bar 5, choosing the backlash in the thread and in the doors of the carriage. The nut 8 is rotated by the gear 9 mounted on the shaft of the stepper motor 10. fixed on the half of the carriage 2. On each half of the carriages 2 and 3 mounted on the probe 11 with knife supports 12, covering the test sample 13. On each probe two walls are made 14 , on each side of which are strain gauges 15, mounted in measuring bridges. Each part of the carriage is provided with a driver 16c with a nut 17 fixed by someone who are screwed with a second micrometer screw 18 having two thread sections of different pitch or direction. The second screw is driven in rotation by a second step motor 19, bounded by rotation of the following spring-loaded rollers 20 on key 21. fixed on the half of the carriage 3. The second carriage is the mirror image of the first one. 1 il.

cl

with

oh oh,

with

about

Yu

The invention relates to a measurement technique, to a means of measuring the deformation of samples when tested.

The purpose of the invention is to increase reliability and accuracy.

The drawing shows an automatic strain gauge.

The strain gauge consists of a micrometer screw 1, on which half of the carriages 2 and 3 are hinged on the door hinge with the help of bracket 4, the bar 5 is pressed against the nut 6 with the ring gear, and the carrier 8 rotates the nut 8, which serves as a support for the bar 5, which chooses the backlash in a carving and in carriage joints. The nut 8 is rotated by the gear 9 mounted on the shaft of the stepper motor 10 mounted on the half of the carriage 2. On each half of the carriages 2 and 3 is mounted on the hoop 11c with knife supports 12 covering the test sample 13. On each probe two walls 14 are made, On each side of which are glued strain gauge 15, mounted in the measuring bridges. Each part of the carriage is provided with a driver 16c by a nut 17 fixed to it, which are screwed with a second micrometer screw 18 having two thread sections of different pitch or direction. The second screw is held in rotation by a second step motor 19, bounded by rotation of the following spring-loaded rollers 20 via a key 21 fixed on the half of the carriage 3. The second carriage is the mirror image of the first one.

The strain gauge works as follows.

With the help of engines 10, both carriages with a predetermined base are installed — the distance between the knife supports of the carriages. A signal is then given to fasten the probes on the sample, while the motor 19, when rotated, brings the probes closer before the knife supports penetrate into the sample with a normalized force determined by the signal of the strain gauge bridge formed on the vertical walls of the probes of each carriage. Further, when loading the sample 13, its sections covered by knife supports begin to move, causing a signal of the measuring bridge mounted on horizontal walls 14, which in the transformed form is fed to the stepper motor 10, and the carriage will move in the direction of movement of the sample section until the signal of the measuring bridge, i.e. The stepper motor system is fixed by a counter and corresponds to the movement of the sample cross section covered by the probes, and the difference in movement of the sample cross sections corresponds to its deformation limited by these cross sections.

The thinning of the sample during its loading will lead to a decrease in the measuring bridge signal of the vertical walls of the probes, which is compensated by the motor 19 to the specified hold-down pressure of the knife supports 2. Thus, the difference in the number of pulses of a stepper motor between the initial clamp of the sample and its value during the loading of the sample will correspond to the magnitude of its thinning.

Claims (1)

The test sample 13 itself is used as a key preventing rotation of the carriages around the micrometric screw 1. The invention claims An automatic strain gauge containing two carriages, a stand on which the carriages are fixed with the possibility of longitudinal movement, two drives for moving the carriages, four probes with supports at the ends, designed for contact with the sample and fixed on the carriages in pairs with the possibility of independent movement in the carriage plane, characterized in that, in order to increase reliability and accuracy, the stand is made in the form of a micrometric screw, the strain gauge is equipped with second and third micrometric screws, each with two thread sections with opposite threading or with threading at different pitch and located perpendicular to the first micrometer screw; two drives for moving the probes in planes, perp Endicary to the first micrometric the screw, each of which is kinematically connected, respectively, with the second and third micrometric screws, each probe is made in the form of a two-stage strainer, the plane of the steps of which perpendicular, and kinematically connected with the corresponding thread section of the respective micrometer screw, and each level of the strain gauge is electrically connected with a corresponding drive for moving the probes in the direction of the least rigidity of the steps of the strain gauge.