RU2295074C1 - Dynamic damper of vibration of rotating bodies - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: damper comprises inertia masses connected with the body by means of bent flat springs connected with the supports. The supports are arranged over periphery of the ring fit on the body with interference. Each pair of the support is connected with the flat spring. The rigidity of the flat spring increases linearly with load due to the screws stops adjusted in height and mounted on each support near the ends of the flat spring from its outer side. A relationship between the length of the flat spring and the corresponding value of the angular velocity of the body is proposed.

EFFECT: expanded functional capabilities.

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Description

The invention relates to damping vibrations and shocks of machines and mechanisms.

There are known dynamic dampers of bending / transverse / oscillations of rotating bodies, which almost always accompany their torsional vibrations due to the presence of minimal imbalance, containing mass and an elastic element connecting the mass to the body, while the mass is either connected by a bearing to an external movable supporting element / cm. A.S. USSR No. 1647178, cl. F 16 F 15/02, 1988 [1], / or is made in the form of a float placed in a cavity filled with the working medium in the shaft / cm. A.S. USSR No. 638769, class F 16 F 15/10, 1977 [2].

Also known are dynamic dampers of torsional vibrations of rotating bodies, either containing a centrifugal mechanism in the form of radial guide grooves mounted on the body and spring-loaded inertial elements / cm. A.S. USSR No. 1588941, class F 16 F 15/14, 1987 [3], a.s. USSR No. 1728561, class F 16 H 15/26, 15/30, 1/20, 1989 [4] /, or the driving and driven friction elements introduced into contact by means of a centrifugal mechanism rigidly fixed to a rotating body / see A.S. USSR No. 577333, cl. F 16 F 15/10, 1976 [5] /.

The disadvantages of all known devices are the significant complexity of the designs, and most importantly - limited functionality. The latter is explained by the possibility of damping by known constructions of only one type of vibration of rotating bodies - either torsional or bending / transverse /, as well as tuning the dampers to only one fixed frequency of spurious oscillations corresponding to one given angular velocity of rotation of the body, the impossibility of automatic adaptive tuning of the dampers to other frequencies when changing the angular velocity of rotation of the body.

The closest device of the same purpose to the claimed invention in terms of features is a dynamic vibration damper containing mass connected to the body through curved flat springs articulated with supports mounted on the body guide with the possibility of moving along it using a special screw with left and right thread, screwed into the holes in the supports with a thread of the corresponding direction / cm. A.S. USSR No. 1283456, cl. F 16 F 15/03, 1985 [6] /, and adopted as a prototype.

The disadvantage of the prototype device is its limited functionality, which is explained by how to configure the device in the process of adjusting it to only one given damping frequency, and, accordingly, the inability to automatically adapt to different frequencies, and the inability to use the device at the same time to damp bending / transverse / torsional vibrations of rotating bodies.

The essence of the invention lies in the use of non-linear mechanical vibrational systems as quenching mechanisms, made in the form of inertial masses placed uniformly around the perimeter of a rotating body, mounted on flat springs with linearly increasing stiffness with increasing load due to switching off part of its working length during spring deformation due to smooth landing of the spring on height-adjustable screw stops.

The technical result is the expansion of the functionality of a dynamic vibration damper of rotating bodies.

The specified technical result in the implementation of the invention is achieved by the fact that in the known dynamic vibration damper of rotating bodies containing inertial masses connected to the body through curved flat springs connected to the supports, the feature is that the supports are placed evenly around the entire perimeter of the tightly worn body and coaxial with the axis of its rotation of the ring with a flat spring attached to each pair of supports, having a variable stiffness linearly increasing with increasing load due to installation on azhdoy support near the ends of the spring with its outer side height-adjustable screw stops, the working spring length l _p associated with a respective value of the angular velocity of the body (the ratio of _{l p = l (ω min /} ω) 2/3, where l - length of the spring ; ω _min is the minimum value of the angular velocity of the body.

The invention is illustrated in the drawing, which schematically shows a rotating body with the proposed damper with a cross section.

The dynamic vibration damper of the rotating body 1 contains inertial masses 2 connected to the body 1 through curved flat springs 3 connected to the supports 4, while the supports 4 are placed evenly around the entire perimeter of the ring 5 attached to the axis of rotation and coaxial with the axis of rotation of the ring 5 to each pair of supports 4 with a flat spring 3 having a stiffness variable linearly increasing with increasing load due to the installation on each support 4 near the ends of the spring 3 from its outer side height-adjustable screw stops 6 screwed into ikreplennye to supports four arms 7 having a bevel facing the springs 3 sides with an increase in the clearance between the spring 3 and the bracket 7 as the distance from the support 4, wherein the working spring length l _p associated with the corresponding value of angular velocity ω ratio l _p = l (ω _min / ω) ^2/3 , where l is the length of the spring; ω _min - the minimum value of the angular velocity of the body. The supports 4 are made integral with the steel ring 5 in the form of flat ribs on the side surface of the ring, the inertial mass 2 is made in the form of flat springs 3 steel balls soldered to the center of the ring.

The work of the proposed device is as follows.

, где ω²R=a_n - центростремительное ускорение; m - величина инерционной массы; R - расстояние от массы 2 до оси вращения тела 1. Силы являются для пружины 3 постоянной нагрузкой, приложенной посередине в направлении наружу от тела 1. Как известно, круговая частота колебаний пружина-масса определяется как

, где С - изгибная жесткость плоской пружины. Гашение поперечных колебаний происходит при равенстве частоты ω' угловой скорости вращения ω. Согласно существу изобретения жесткость С линейно возрастает с увеличением нагрузки F^u, то есть выполняется соотношение

, где κ - постоянный коэффициент. Тогда формулу /2/ перепишем в виде

/4/. Так как

/изменением величины R при изгибе пружины по сравнению с гораздо большими расстояниями от оси вращения тела до пружины можно пренебречь/, то выполнение условия /3/ неизбежно приводит к автоматической адаптивной перестройке гасителя. Например, при исходной настройке гасителя на угловую скорость ω и при увеличении ω в n раз центробежная сила инерции F^u, то есть сила нагрузки на пружину, увеличится в n раз, во столько же раз увеличится жесткость C пружины, и частота настройки гасителя ω' увеличится в

, то есть также в n раз. Теперь, после объяснения необходимости выполнения для автоматической настройки гасителя формулы /3/, опишем механизм реализации данной формулы в предложенном устройстве. При минимально возможной для данного тела угловой скорости вращения ω_min пружины 3 под действием силы

слабо прогибаются наружу и не касаются винтов 6, при этом их жесткость равна C_min, то есть исходная жесткость непосредственно самой пружины, и совместно с массой m подбирается необходимое условие гашения поперечных колебаний

.In the presence of minimal imbalance of the body 1, that is, in practically all cases, the rotation of the body 1 is accompanied by the appearance of its parasitic transverse / bending / vibrations occurring in radial directions with a frequency equal to the angular velocity ω of the body's rotation. On masses 2, when the body 1 rotates, centrifugal inertia forces act in radial directions to the periphery

where ω ² R = a _n - centripetal acceleration; m is the value of the inertial mass; R is the distance from the mass 2 to the axis of rotation of the body 1. The forces for the spring 3 are a constant load applied in the middle in the direction outward from the body 1. As you know, the circular frequency of the spring-mass oscillations is defined as

where C is the bending stiffness of a flat spring. The damping of transverse vibrations occurs when the frequency ω 'is equal to the angular velocity of rotation ω. According to the essence of the invention, the rigidity C increases linearly with increasing load F ^u , that is, the relation

where κ is a constant coefficient. Then we rewrite the formula / 2 / in the form

/four/. As

/ the change in the value of R during bending of the spring compared to much greater distances from the axis of rotation of the body to the spring can be neglected /, then the fulfillment of condition / 3 / inevitably leads to automatic adaptive rearrangement of the damper. For example, when the damper is initially tuned to the angular velocity ω and when ω increases by a factor of n, the centrifugal inertia force F ^u , that is, the load force on the spring, increases by a factor of n, the spring stiffness C increases by the same amount, and the damper’s tuning frequency ω ' will increase in

, i.e. also n times. Now, after explaining the need to execute the formula / 3 / for the automatic adjustment of the damper, we will describe the mechanism for implementing this formula in the proposed device. At the minimum possible for a given body angular velocity of rotation ω _{min of the} spring 3 under the action of a force

slightly bend outward and do not touch screws 6, while their stiffness is equal to C _min , that is, the initial stiffness of the spring itself, and together with mass m, the necessary condition for damping transverse vibrations is selected

.

и закрепленной по обеим концам изгибная жесткость C_min определяется по формулам, полученным в книге А.Д.Нестеренко, П.П.Орнатский "Детали и узлы приборов", Гостехиздат УССР, Киев - 1963 [7] на стр.149-150,For a flat spring of rectangular cross section, loaded in the middle by force

and the flexural rigidity C _min fixed at both ends is determined by the formulas obtained in the book by A. D. Nesterenko, P. P. Ornatsky, "Parts and Components of Instruments", Gostekhizdat of the Ukrainian SSR, Kiev - 1963 [7] on pages 149-150,

. При увеличении угловой скорости пружины 3 выгибаются наружу и плавно ложатся на регулировочные винты 6, при этом рабочая длина l_p пружины становится меньше (и равна расстоянию между последними из винтов 6 с двух сторон, на которые опирается пружина 3; X - расстояние от края пружины 3 /места ее крепления к опоре 4/ до данного винта. При таком опирании l_p постепенно уменьшается, жесткость С пружины нарастает. По существу изобретения винты 6 установлены так, то есть так выбраны расстояния x, что с увеличением нагрузки F^u жесткость С нарастает линейно /см. формулу /3/. При значении угловой скорости ω>ω_min из /4/ имеем

, и приравнивая к /3/, находим

, откуда

где

- постоянный коэффициент. Так как из /5/ следует, что

то

, и выражение /5/ перепишем в виде

, причем, так как l_p=(l-2x), то значение x можно выразить в виде

. Таким образом, при осуществлении эффекта гашения на частоте ω_min путем подбора величин C_min и m гашение на любой более высокой частоте ω поперечных колебаний осуществляется автоматически, но при этом частоте ω/угловой скорости вращения/ должно соответствовать расстояние l_p или, что тоже самое, расстояние x от края до соответствующего регулировочного винта 6. При регулировке устройства последовательно на каждой угловой скорости (в процессе ее возрастания соответствующие винты 6 последовательно на расстояниях x должны быть ввернуты до контакта с прогнутой пружиной 3 и законтрены. Таким образом, расчетные расстояния l_p или x рассчитываются теоретически по предложенной формуле /6/ и выполняются в процессе изготовления устройства, а радиальные расстояния /смещения винтов 6 вдоль оси их вращения/ до касания винта с пружиной 3 выставляются в процессе регулировки устройства. Этим и обеспечивается заданная жесткостная характеристика пружин 3 с линейно возрастающей с увеличением нагрузки жесткостью, за счет чего и обеспечивается эффект автоматической настройки гасителя на любую частоту вращения.

. With an increase in the angular velocity, the springs 3 bend outward and lie smoothly on the adjusting screws 6, while the working length l _{p of the} spring becomes smaller (and is equal to the distance between the last of the screws 6 from two sides on which spring 3 rests; X is the distance from the edge of the spring 3 / places of its attachment to the support 4 / to this screw. With this bearing, l _p gradually decreases, the spring stiffness C increases. In essence, the screws 6 are installed in such a way, that is, the distances x are chosen so that the load stiffness C increases with increasing load F ^u linear / s m. the formula / 3 / .With the value of the angular velocity ω> ω _min from / 4 / we have

, and equating to / 3 /, we find

from where

Where

is a constant coefficient. Since from / 5 / it follows that

then

, and the expression / 5 / can be rewritten as

, moreover, since l _p = (l-2x), the value of x can be expressed as

. Thus, when the damping effect is realized at the frequency ω _min by selecting the values of C _min and m, the damping at any higher frequency ω of transverse vibrations is carried out automatically, but at this frequency ω / the angular velocity of rotation /, the distance l _p must correspond or, what is the same , the distance x from the edge to the corresponding adjusting screw 6. When adjusting the device sequentially at each angular velocity (during its increase, the corresponding screws 6 must be screwed in successively at distances x to the contact and with a bent spring 3 and locked in. Thus, the calculated distances l _p or x are calculated theoretically by the proposed formula / 6 / and are performed during the manufacturing process of the device, and the radial distances / displacements of the screws 6 along the axis of rotation / until the screw touches the spring 3 This ensures the specified stiffness characteristic of the springs 3 with stiffness linearly increasing with increasing load, due to which the effect of automatic adjustment of the damper to any frequency is ensured. in rotation.

If, for example, l = 100 mm, n _min = 3000 rpm, ω _min = 314 rad / s, then using the formula / 5 / for n = 5000 rpm, ω = 523 rad / s, we calculate l _p = 71 mm, respectively x = (ll _p ) / 2 = 14.5 mm, that is, to extinguish the damping effect at an angular velocity of ω = 523 rad / s, the spring should be supported on both sides by extreme screws, up to the screws removed from support 4 on x = 14.5 mm and have a working length of 71 mm with a full length l = 100 mm. When parasitic torsional vibrations of the body 1 occur, that is, with variations in its angular velocity relative to the nominal value, the damping process occurs as follows. For example, with a certain increase in the angular velocity of mass 2 under the action of centrifugal inertia forces, they move away from the axis of rotation of body 1, while the axial moment of inertia of the system increases, causing the angular velocity to return to its nominal value.

The proposed dynamic absorber is characterized by extremely wide functional capabilities, allowing simultaneously damping both torsional and transverse / bending / vibrations in any of the radial directions, as well as automatically adaptively adjusting to different damping frequencies when the angular velocity of rotation of the body changes. The device is quite compact, consists of simple elements and nodes, can be made in almost any arrangement in the form of a removable module, worn on the body when working with the possibility of easy removal, for example, during transportation and storage of bodies, etc.

Claims (1)

A dynamic vibration damper of rotating bodies, containing inertial masses connected with the body through curved flat springs connected to the supports, characterized in that the supports are placed uniformly around the entire perimeter of the ring that is tightly worn on the body and coaxial with its axis of rotation with a plane attached to each pair of supports a spring having a variable rigidity linearly increasing with increasing load due to the installation of height-adjustable screw stops on each support near the ends of the flat spring on its outside, at ohm, the working length of a flat spring l _p is related to the corresponding value of the angular velocity of the body ω by the ratio l _p = l (ω _min / ω) ^2/3 , where l is the length of the flat spring; ω _min - the minimum value of the angular velocity of the body.