SU693323A1 - Ring balance - Google Patents

Description

(54) TORQUE SCALES

one

The invention relates to metrology and can be used in the determination of the Gravitational constant, the development of gravitational variameters, the study of the interaction of light with matter.

Torsion scales in the form of a lever with weights at the ends, suspended by means of a torsion thread 1, 2, are known. They are characterized by a high level of loss when measuring, caused in particular by convective air movements that occur when the temperature changes.

Also known are torsion scales containing a yoke with weights and a mirror, suspended by means of a torsion thread in an evacuated body f3i

The aim of the invention is to reduce the error rate in measurement.

To achieve this, a thermal compensating device in the form of a massive body mounted on the end of the rod, which is located along the balance line of the rocker arm and connected to the body by means of the adjustment, position and length of the rod, is installed in the torsion balance; besides, the latter is made in the form

tripod, equipped with stoor and running gears and carriage.

The drawing shows a diagram of torsional weights.

The proposed torsion balance contains a beam 1 with weights 2 and 3, suspended in an evacuated body 4 on the torsion thread 5, and a thermal compensating device containing a massive body 6 fixed at the end of a temperature-sensitive rod 7. The latter is made, for example, from organic glass, fluoroplast or ebonite and set along

5 equilibrium lines of the rocker arm 1. The other end of the rod 7 is fixed in the sleeve 8 by a locking screw 9. A stand 10 connects the sleeve 8 fixed by the screw 11 with the carriage 12 mounted on

0 onto the lead screw 13 and inside the direction toward the cylinder 14. The rack 10 passes through the through-guide groove of the cylinder 14 and together with the carriage 12 can move

5 without rotation within this groove only in the axial direction of the cylinder 14, the lead screw 13 is fixed in the inner ring of the bearing 15. The flange 16 presses the outer ring

0 of the bearing 15 to the cylinder 14, the lock nut 17 fixes the inner ring of the bearing 15. On the running screw 13, the flywheel 18 of the fine tuning of the temperature compensation is fixed. A tripod 19 connected to the guides of the cylinder 14 is mounted on the housing 4. The tripod 19, the cylinder 14 with the carriage 12 and the sleeve 8 with the screw 9 serve as a mechanical regulator of the position and the length of the rod 7. During eruptions with these torsion bars the weights of the quantity being studied, for example, the constant tension /, as a measure can be used either the period T of oscillations of the rocker arm (dynamic mode), or the deviation of the rocker arm 1 from the initial set of equilibrium (static mode). t) bb these parameters are the dimensions of the torsion balance and the torsional rigidity X of the thread 5. However, it is known that both the dimensions and the rigidity change in the year with a change in TeMnejpaTyjMii. To compensate for this B; reddn of the temperature effect, an array of body b is used, which adds to the core the 5 s of the thread 5 1С1 the weight of the piston rigidity equal to (for small amplitudes of torsional oscillations); Pack 1, / 1 ():: where X is the gravitational intensity; t, M is the mass of GRU§oj3 2 or 3 and body mass b, respectively, t, Bj is the distance from the axis of rotation of the rocker arm 1 to the centers of mass of the goods 2.3 and body b, respectively. Pin 7, the linear expansion coefficient of which far exceeds the linear expansion coefficient. The material of the rocker arm 1, with temperature fluctuations, moves te b along the equilibrium lines of the korogFlash. This changes the distance, which (at 3L a) agrees formula (1) to the temperature coefficient TTMotTt W .. timttmgchii "f ar Tv / M- tif t cient (i gravitational rigidity is equal to where OS is the length of the section of the rod 7 from the locking screw, 9 to the end carrying the body) B. At temperature, the torsion balance error in the dynamic mode of operation when the temperature changes by the value AT о (., X Ar rf.3: ... T - TG - 2. where lt is the change in the period of oscillation of the core when the temperature changes by 1 ° C; the temperature coefficient of the elastic modulus of the material of the suspension yarn 5; o (.j is the linear expansion coefficient of the material of the yarn 5. From formula (3) it can be seen that, in order to achieve temperature compensation of the ests, it is necessary that Equal part was equal to the sum of three steel members.In a tungsten iti suspension, manufacture an Ormoscale of light non-magnetic materials (quartz glass, sital) with a linear linear expansion coefficient. From expressions (2) and (3) we get the temperature compensation equation in the form.,. A. () 3di.x Provided () is also true for the static operation mode of the balance. It follows from Eq. (4) that the temperature diminution of the balance can be minimized by choosing the length L of rod 7 (coarse compensation) with the subsequent setting of the distance,. and between the interacting masses 3 and b with the help of a flywheel 18. Let Y 0rlf which is easy to provide for scales with. 10 C, and -2 cm, d. -1.-LOT Then, in order to provide temperature compensation, a rod with a length of 4 cm is required. If X-5.,. B-10 cm, in-1 g, then to obtain X, -5 .10-CGS, body b must have mass M-5d g (body radius b at a density of 8.5 gsm will be 1.1 cm). Such a mass can be placed in such a way that a 2 cm is established on the balance line of the rocker arms 1. The criterion for the correctness of such an installation is the equality between the time intervals during which the moving arm is located on opposite sides of the initial equilibrium position. The proposed torsion balance provides a reduction in temperature error, mainly due to the thermoelastic coefficient of the tungsten suspension thread (, b. 10), approximately by two orders of magnitude. Consequently, the magnitude of the magnitude will be 4. In the presence of optimal geometry and magnetic damping of oscillations, such scales will provide metrological measurements in conventional laboratory conditions. The accuracy of determining the gravitational constant on long-period vacuum scales can be 10. Measurement error at field gravitational variometers, made on the basis of the proposed torsion weights. Will drop to the hundredths of an answer.

Claims (3)

1. Torsion scales containing a yoke with weights and mirrors, suspended using torsional nit in an evacuated body, characterized in that, with the aim of reducing the temperature error in the measurements, they are equipped with a thermal compensating device in the shape of a massive body reinforced on. concession, which is located along the balance line of the rocker and is connected to the body through position adjuster and rod lengths. 2. Libra pop, 1, is different from JI and e with the fact that mechanical The pszhozheni and rod length regulator is made in the form of a tripod, equipped with its stopset-G-db-ynsh-in-piece and carriage. Sources of information taken into account in the examination 1. Sagitov M.U. Permanent and ground mass, 1969, pp.48-85. 2. Braginsky V.B. Physical experiments4) with Test Bodies, 1970, p.67.  3. Karagioz, O., et al., On the definitions of gravity ion constant evacuated by vacuum futile weights. Lime USSR Academy of Sciences Physics of the Earth, № 5, 1976, p.108.