SU885838A1 - Two-element dynamometer - Google Patents

Description

(54) TWO-COMPONENT DYNOMOMETER

The invention relates to a force engineering technique and can be used to measure the component cutting forces on a rotary shaft with a shaft, for example, when milling. A dynamometer for measuring the tangential and radial components of the cutting force, containing strain gauges placed immediately on a rotating shaft and stationary supports, is known. A disadvantage of the known dynamometer is the low measurement accuracy due to the unstable operation of the current collector and the shaft beat. The closest in technical essence to the present invention is a dynamometer that contains a deformable shaft, mounted on it beam elastic elements with strain gages included in measuring circuit 2. The disadvantage of this dynamometer is also low accuracy and measurement. . . The chain of invention is the elevation of the points. measurement. This goal is achieved by the fact that the device is equipped with two bearings, on which two pairs of beam elastic elements are installed, placed in two mutually perpendicular planes passing through the shaft axis, while the elastic elements of each pair are fixed with their opposite hooks on the stationary outer rings of the bearings whose inner rings are fixed at the ends of the shaft, and the free ends of the said elastic elements are mounted with tension on the balls placed on the outer rings of the bearings. At the same time, strain gauges located on planes of girder elastic elements of one pair facing the shaft are included in the adjacent arms of the bridge measuring circuit, with two shoulder gauges included in each shoulder of the bridge measuring circuit. FIG. 1 shows the proposed device, a general view; in fig. 2, section A-A in FIG. one; in fig. 3 arrangement of the dynamometer on the hobbing machine; in fig. 4 is an electrical wiring circuit of strain gauges for measuring one component of the force; in fig. 5 - bend diagram

rotating shaft under the action of one component of the force.

A two-component dynamometer for measuring the inter-perperidicular components of the cutting force on a rotating deformable shaft 1 contains four elastic beam elements 2-5, rigidly fixed through sleeves 6 and 7 on the outer rings of the two bearings. Beam elements 2 and 3 serve to measure one component of the cutting force, elements 4 and 5 for the other.

The free ends of the girder resilient elements rest on the balls 8 and 9 mounted on the outer ring of the other bearing. On two opposite planes of each elastic element, perpendicular to the direction of action of the measured force, in places equidistant from the cantilever-clamped end of the beam element, there is glued on one strain gauge, which are included in the bridge circuit (Fig. 4).

Using eccentric screws 10, the elastic elements 3 and 4 are able to move parallel to the axis of the shaft and then rigidly fasten them on the sleeve 7 with screws M in the longitudinal grooves of the elements

The guide pins 12, mounted in the grooves of the elements and the openings of the sleeve 6, are removed after the adjustment has been made.

The bearing play is knocked out by two springs 13. The dynamometer is electrically isolated from the machine body by a gasket 14 and bushings 15. A screen 16 electrically connected to the machine body is fixed to the sleeve 7 by means of textile sectors 17.

With the fixed parts of the equipment, the dynamometer is connected with cables .18 and springs 19 by means of adjusting nuts 20 and 21 and studs 22 screwed into the machine body (Fig. 3).

Load cells whose label is shown on the screen. 1 are included in the bridge circuit of FIG. 4. The two constant resistances in the amplifier in FIG. 4 not-shown.

The dynamometer works as follows.

When the force is applied, the shaft (Fig. 5 has a deflection in the section B-B-f and in the section C-C-fj. The difference in the deflections f and f causes bending of the beam elastic, elements fixed on the bearings, which are installed in the above sections.

During bending of the shaft 1 floor by the action of the measured force, the section B – B rotates about point O (Fig. 1). At the same time, the beam tensor element 4 fixed on the upper bushing and the ball 9, which rolls over beam member 5, rotate along the beam element 5, does not cause its comparable deflection. The relative deformations of the girder elastic elements caused by these rotations are not equal to each other, and consequently, the resistance of the strain gauges is not equal, which causes imbalance of the bridge, determined by the value of the applied force.

The deflection of the beam elements will occur not only under the influence of the bend of the shaft 1, but may also be caused by face and radial runout of bearings. Since the deformation value of both beam elements caused by face runout of bearings is the same, the bridge will remain balanced. Radial runout, for example, of the upper bearing with respect to the lower one, equally deflection of the beam strainer elements in the direction perpendicular to the shaft axis, will not cause imbalance of the bridge.

. Let the beating of the upper bearing with respect to the lower one (Fig. 1) is directed to the right. In this case, the strain gauges R and R are compressed, and R and R are stretched by the same amount. Assuming the initial resistance of each arm of the bridge is equal to 2R. Assuming that as a result of the deformation caused by the beating, the resistance of each strainer changes to AR, we obtain new resistances of each strainer

The total resistance of each arm of the bridge (Fig. 4) in this case is equal to

R + R R - AR 4-R + UR 2R

R2 + R4 R + R + R AR 2R, i.e. the resistance of the shoulders of the bridge remained the same and, therefore, the signal at the output of the bridge, caused by the radial runout of the bearings, is zero. Consequently, the dynamometer will only feel the bending deformations of the shaft caused by the measured components of the cutting force.

The proposed design of the dynamometer ensures continuous measurement of the component cutting forces, the absence of mutually measurable components, insensitivity to vibrations, and, consequently, an increase in the accuracy of measurements.

Claims (2)

Invention Formula A two-component dynamometer containing a deformable shaft, beamed elastic elements installed on it with strain gauges included in a measuring circuit, characterized in that, in order to improve the measurement accuracy, it is equipped with two bearings, on which two pairs of beamed elastic elements placed in two mutually perpendicular planes passing through the shaft axis, while the elastic elements are fixed with their opposite ends on the fixed outer rings of the bearings, the internal rings The ends of which are fixed at the ends of a weighing rod, and the free plates of the specified elastic elements are mounted with a tightness on the balls placed on the outer rings of the bearings, 2. The dynamometer according to claim 1, characterized in that, in order to eliminate the error from the ball bearing bearings, strain gauges Fig. 2, located on the planes of the beam-like elastic elements of one pair facing the shaft, are included in the adjacent shoulders of the bridge measuring device, with two strain gauges on each shoulder of the bridge measuring circuit. Sources of information taken into account in the examination 1. Gulida E.N. Measurement of cutting force and torques during gear milling. Izdtvo Lviv University, 1966, p. 77-79. 2. Works of the Volgograd Polytechnic Institute. Volgograd, 1971, p. 258-260, fig. 1 and 2 (prototype). one