SU1728684A1 - Force measuring device - Google Patents

Abstract

The invention relates to instrumentation engineering and makes it possible to increase the accuracy of force measurement. acting on the rotating shaft of the device with three angular contact bearings. Four pairs of strain gauges RI and R2, Ra and R, RS and Re, R and RS are placed on the outer bearing race. Each pair of strain gages are combined into a half bridge, and diametrically opposite half bridges are combined into the first / Ri, RI. R3 and R4 / and second / Rs. Re. R, Re / Wheatstone measuring bridges with counter-connection of the strain gages of adjacent arms. The magnitude of the force FX is determined by the signal from the first measuring bridge, and the magnitude of the force Fy by the signal of the second measuring bridge. To determine the magnitude of the force acting along the axis of the bearings on the outer cages of the second and third bearings, resistors were installed, placed similarly to one of the measuring bridges of the first bearing, and combined into the third and fourth measuring bridges of Wheatstone My turn on the strain gauges adjacent bridge arms. The magnitude of the force acting along the axis of the bearings is determined by the signal taken from the third output of the measuring circuit. 9 il. (Ls

Description

The invention relates to force-measuring technique and can be widely used in measuring the radial and axial forces acting on a rotating shaft in terms of the magnitude of the reactions that occur in the shaft rolling support bearings.

In the particular case, the invention can be used in measuring and monitoring the cutting forces of metalworking machines for technical and technological control over the machining processes of parts on machines operating in unmanned mode in CNC systems or other similar systems.

Known load device, made on the basis of strain gauge measuring rings. The disadvantage of the device is the complexity of the structure and the limitations of its use.

The closest in technical essence to the invention is a device for measuring the forces acting on a rotating shaft using rolling bearings, on the holder of which the strain gages are fixed.

The disadvantage of these devices is the high temperature measurement error due to the appearance of apparent deformation due to changes

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temperatures, as well as the impossibility of eliminating the interoperability of measuring circuits when using angular contact bearings.

The purpose of the invention is to improve the accuracy of measuring the forces acting on a rotating shaft.

Fig. 1 shows a structural block diagram of a strain gauge device; Figures 2 to 4 are diagrams showing the relative orientation of the measuring axes of the bearing strain gauge bridges for measuring the three components of the load force on the shaft; Fig. 5 illustrates the arrangement of the strain gauges on the bearing for measuring the vertical and horizontal components of the measured force; Figures 6-7 are electrical connection diagrams of strain gauges on a bearing for measuring the horizontal and vertical components of the measured force; FIGS. 8-9 are electrical connection diagrams of the strain gauges of the measuring bridges of the bearings for measuring Y, Z — components of the force applied to the shaft shown in FIG.

Load device contains a strain gauge transducers (sensors) 1 and an electronic module 2, designed for pre-processing of information (figure 1).

The electronic module contains four measuring channels made in the form of series-connected high-frequency filters 3, amplifiers4 ac current, rectifiers 5 and low-pass filters b, two normalizing elements 7, 8 and three subtraction elements 9, 10 and 11.

The output of the first measuring channel is the first output of the device - Output X, the output of the second measuring channel is the second output of the device - Output Y and connected through the corresponding normalizing elements 7 and 8 to the first inputs of the first and second elements of the subtraction 9 and 10, the output of the third measuring channel connected to the second input of the first subtraction element 9, the output of which is connected to the first input of the third subtraction element 11, the output of the fourth measuring channel is connected to the second input of the second subtraction element 1 0, the output of which is connected to the second input of the third subtraction element 11, the output of which is the third output of the device - Output Z.

The strain gauge transducer includes three angular contact bearings 12, 13, 14, on the outer cages of which are mounted strain gauges (Figures 2-4),

The optical image of the stress of a loaded bearing, obtained by photoelasticity, makes it possible to establish, using isochromatic lines, a pattern of stress distribution and strain on the outer race of the bearing. The load on the outer race of the bearing is transmitted through the contact of the rolling elements and the yoke. Longitudinal deformation zones are formed above the contact point in the cage, which rotate with the rolling bodies as the bearing rotates.

The measurement of the magnitude of these deformations is made by strain gauges RI,

RIRi6, whose output is an alternating voltage with an amplitude proportional to the magnitude of the deformations of the rotating zones, which in turn are proportional to the force.

acting on the bearing. The output signal of the measuring circuit of the strain gages is fed to the measuring channel.

The output of the measuring channel is then fed to a recording device (for example, a CNC or other other signal processing system).

To increase the sensitivity of the device, as well as the convenience of placing the strain gauge measuring circuits in the bearing outer ring, a longitudinal circular groove is grooved, the geometrical dimensions and place of which are determined by the type of the supporting bearings and other design features of the shaft support unit.

To increase the sensitivity of the measuring strain gauges, as well as to exclude the temperature error of the measurements, the strain gauges are combined into Whitston bridges 12, 13, 14, 15.

The proposed device for measuring orthogonal radial component forces uses a first bearing.

12 shaft supports, and the second 14 and third 14 bearings of the shaft support assembly are used to measure axial forces in two opposite directions.

On the first bearing placed two

measuring strain gauge bridge Uyston RI. R2, P3, R4 and Rs. RG, Ry, Re (Fig. 67) Strain gages are placed on the outer bearing race in pairs in a row.

at the same time the distance between the strain gauges in each pair does not exceed the length between the points of intersection of the normals, conducted through the points of contact of the two nearest rolling bodies with the outer yoke

bearing, and are connected in half bridges, shifted on the cage one relative

the other by 90 °, thus forming two pairs of diametrically opposite half-bridges.

Opposite half-bridges are combined into Wheatstone measuring bridges, with the strain gauges of the adjacent bridges of the bridges being switched in opposite, i.e. at each moment of time when the bearing rotates, the strain gauges of the adjacent arms of the bridge are in exactly the same position relative to the rotating rolling bodies (Figures 7-8).

The diagram of the connection of the strain gauges makes it possible to eliminate the influence of axial force when measuring the radial component forces due to the well-known features of the Wheatstone bridge with the opposing coupling of the strain gauges of its adjacent arms.

Another fundamental difference between the tensor bridge and the previously known ones is the orientation of the strain gauge half bridge on the outer bearing race along the measuring axes of the action of the orthogonal radial component forces. In this way, the mutual influence of the radial component forces on their measuring circuits is eliminated, and at the same time the measurement of forces is provided. acting along the measuring axes, both in one and in the opposite direction.

Under the action of a force along the Fx axis, half-bridge strain gages Ri work. Ra. under the effect of the opposite direction, the resistance strain gages Ra, R work. Similarly, the resistance strain gages of the measuring bridge Rs work. Re, R, Re when measuring another radial component acting along the Fy axis.

The layout and connection of the strain resistors on the outer sleeves of the second and third bearing for measuring the axial component of the force is shown in Figures 8-9. On each cage there is one measuring strain gauge bridge, and the strain gauges are also placed. Pairwise similarly to the strain gauges of one of the Wheatstone bridges of the first bearing.

However, the connection of the strain gauges to the bridge circuit is characterized in that the inclusion of the strain gauges of the adjacent arms of the bridge is straight, i.e. when the bearing rotates, the resistance strain gages of the adjacent arms of the bridge undergo various deformations. Thus, under the action of axial loads, the measuring bridge generates a signal directly proportional to the acting force. At the same time, under the action of a radial load in the direction of the half bridges of the strain gauges, they produce a signal proportional to the radial force.

Therefore, at the output of the measuring bridges of the second and third bearing there is in general a complex signal caused by the action of both the radial and axial components of the forces.

In order to receive a signal only from the action of axial forces. It is necessary to verify the signal subtraction operation, i.e. the signal from the measuring bridge of the first bearing must be subtracted from the total signal of the second and third bearing, and the signal from the measuring bridge of the first bearing must be normalized, i.e. reduce its magnitude to what is perceived on the second and third bearings. The normalization operation is carried out by the elements 7 and 8 of the measuring channels of the device.

FORUMAWLAH AND ISLANDS

A force measuring device containing three angular contact bearings, on the outer cages of which are installed the strain gauges in pairs and shifted 90 ° relative to each other, four measuring channels, two normalizing elements and three subtraction elements, while the strain gauges are connected to the measuring channels made in the form of series-connected high-pass filters, AC amplifiers, rectifiers, and low-pass filters, characterized in that, in order to improve the accuracy, the forces acting on the rotating shaft, the distance between the strain gauges in each pair does not exceed the length between the points of intersection of the normals, conducted through the contact points of the two closest rolling bodies with the outer bearing race, each pair of strain gauges located on the outer race of the first bearing is connected to half bridges diametrically opposite half bridges are combined into the first and second Uiteton measuring bridges with counter-switching of the resistance strain gages of the adjacent arms, and on the outer cages of the second and third The bearings gages are connected similarly to one of the Wheatstone bridge a first bearing and the combined third and fourth Wheatstone bridge, one on each cage with direct incorporation of strain gauges adjacent arm of the bridge, the outputs of all measuring bridges are connected to a measuring channel, the output of the first measuring channel is

the first output of the device, the output of the second measuring channel - the second output of the device, which is connected through the corresponding normalizing elements to the first inputs of the first and second subtraction elements, the output of the third measuring channel is connected to the second input of the first subtraction element, the output

which is connected to the first input of the third subtraction element, the output of the fourth measuring channel is connected to the second input of the second subtraction element, the output of which is connected to the second input of the third subtraction element, the output of which is the third output of the device.

Claims (1)

Claim A force measuring device containing three angular contact rolling bearings 25, on the outer cages of which are installed strain gauges in pairs and 90 ° offset from one another, four measuring channels, two normalizing elements and three subtraction elements, while the strain gauges are connected to the measuring channels, made in the form of series-connected high-pass filters, AC amplifiers, rectifiers and low-pass filters 35, characterized in that, in order to improve the accuracy of the measurement the forces acting on the rotating shaft, the distance between the strain gages in each pair does not exceed the length between the intersection points of the normals drawn through the contact points of the two nearest rolling elements with the outer race of the bearing, each pair of strain gauges located on the outer race of the first bearing is connected in half-bridges, diametrically opposite half-bridges are combined into the first and second measuring Wheatstone bridges with the on-board inclusion of strain gauges of adjacent 50 arms, and on the outer clips of the second and third of its bearings, the strain gages are connected similarly to one of the Wheatstone measuring bridges of the first bearing and combined into the third and fourth Wheatstone measuring bridges, one on each cage with a direct connection of the strain gages of the adjacent arms of the bridge, the outputs of all measuring bridges are connected to the measuring channels, and the output of the first measuring channel is the first output of the device, the output of the second measuring channel is the second output of the device, which is connected through the corresponding normalizing elements with the first inputs of the first and second subtraction elements, the output of the third measuring channel is connected to the second input of the first subtraction element, the output of which is connected to the first input of the third subtraction element, the output of the fourth measuring channel is connected to the second input of the second subtraction element, the output of which is connected to the second the input of the third subtraction element, the output of which is the third output of the device. Figure 2 FIG. 6 FIG. 7 FIG. 8 Fig.9