RU2539810C1 - Method of vertical dynamic balancing of workpiece and device for its implementation - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: offered inventions relate to machine building and can be used for dynamic balancing of various workpieces. The method consists is that a workpiece is rotated on a platform installed on a central hinged support on a rotating table, and dynamic responses between the platform and the table are measured. In addition dynamic responses between the platform and the table are measured at variable mutual vertical position of the hinge of the central support and the workpiece. The device contains the housing, the table installed in it that rotates on bearings with reference to a vertical axis, located on the table central hinged support, which bears the platform for placement of a workpiece, the platform is coupled with the table by means of sensor of dynamic response generated at rotation of the table with a workpiece on it. Central hinged support is designed as gimbals with crossed horizontal axes intersecting a rotation axis, and the platform is designed rotary with reference to vertical axis.

EFFECT: improvement of accuracy of balancing.

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Description

The group of inventions relates to mechanical engineering and can be used for vertical dynamic balancing with a low rotational speed of various products, for example, spacecraft.

A known method of vertical dynamic balancing of a product with a low speed (see "Reference balancing", ME Levit and others - M., "Engineering", 1992. p.210-211), in which the product is rotated on the spindle of the oscillating table and measure the dynamic reactions between the table and the stationary body.

A device is known that implements the above method of vertical dynamic balancing of a product with a low speed, comprising a spindle rotating relative to the vertical axis for installing the product, placed on a table, the table is connected to a fixed base by elastic elements - rods forming an oscillating mechanical system of a pre-resonance type, between the table and the stationary based on the installed sensors of dynamic reactions that occur during rotation of the spindle with the installed product, with which share imbalances.

The disadvantage of this method and its implementing device is the relatively low accuracy of dynamic balancing. The reason for the low accuracy is due to the fundamental necessity of measuring the dynamic reactions of the oscillating system “table + spindle + product”, which has a relatively large intrinsic inertia that significantly affects the accuracy of the measured parameters of the oscillatory motion under the action of small centrifugal forces arising from the rotation of the product with a low frequency.

The closest in technical essence to the proposed technical solution analogues are the method and the device that implements it (see. "Technology for assembly and testing of spacecraft", IT Belyakov and others - M., "Engineering", 1990. p. 212) .

In the known closest method of vertical dynamic balancing with a low speed, the product is rotated on a platform mounted on a central hinge support on a rotating table, and dynamic reactions between the platform and the table are measured.

The disadvantage of this known method, the closest in technical essence to the proposed method, is the limited technical capabilities due to the fact that in dynamic mode it does not allow to separate the static and dynamic imbalances of the product, but is intended only to determine the moment component of the imbalance and moment balancing of the product.

The closest known device for vertical dynamic balancing with a low rotational speed of the product comprises a housing, a table mounted therein rotating on bearings relative to the vertical axis, a central articulated support mounted on the table, on which the product mounting platform rests, the platform is connected to the table by means of dynamic reaction sensors arising from the rotation of the table with the product installed.

The disadvantage of this known device, the closest in technical essence to the proposed device, is the lack of accuracy of eliminating dynamic imbalance, since it does not allow to determine in dynamic mode and eliminate the static component of the dynamic imbalance.

The technical result of this group of inventions is the expansion of technical capabilities due to the additional possibility of determining the static component of dynamic imbalance and improving the accuracy of balancing the product due to the additional consideration of static imbalance, measured in dynamic mode.

To achieve this technical result, in a method for vertical dynamic balancing of a product with a low speed, in which the product is rotated on a platform mounted on a central hinge support on a rotating table, and dynamic reactions between the platform and the table are measured, dynamic reactions between the platform are additionally measured, and a table with a changed vertical relative position of the hinge of the central support and the product.

A distinctive feature of the proposed method from the closest analogue is the operation of changing the mutual vertical position of the hinge of the central support and the product and the subsequent additional measurement of dynamic reactions between the platform and the table.

In a device for vertical dynamic balancing of a product with a low speed that implements the proposed technical solution, comprising a housing, a table mounted therein rotating on bearings relative to the vertical axis, a central articulated support mounted on the table, on which the product mounting platform rests, the platform is connected to the table by means of sensors of dynamic reactions that occur when the table is rotated with the product installed, the central articulated support is made in the form of a gimbal and with crossed horizontal axes intersecting the axis of rotation, and the platform is made rotatable relative to the vertical axis.

A distinctive feature of the proposed device from the closest analogue is the implementation of the central articulated support, which is made in the form of a gimbal with crossed horizontal axes intersecting the axis of rotation, and the platform is made rotatable relative to the vertical axis.

Due to the presence of distinctive features in the proposed technical solution in dynamic mode, the static component of the imbalance is additionally determined, which, together with the moment component, allows you to most fully take into account and eliminate the dynamic imbalance of the balanced product.

The proposed technical solution is illustrated by the drawings presented in figure 1, figure 2 and figure 3.

Figure 1 shows a device for vertical dynamic balancing of a product with a low speed that implements the proposed technical solution.

Figure 2 shows a section along aa.

Figure 3 shows a section along BB.

The proposed device for vertical dynamic balancing of the product contains a housing 1, a bearing assembly 2 mounted therein, for example, an aerostatic table 3 rotating on the bearings of the assembly 2 relative to the vertical axis Ox, a central articulated support on the table 3, consisting of lower 4 and upper 5 parts , on which the platform 6 for mounting the product 7 rests, the platform 6 is connected to the table 3 by means of two pairs of sensors 8, 8 ′ and 9, 9 ′ of dynamic reactions, for example, strain gages, which are equally spaced from the rotation axis Ox ov distance r. The central articulated support, consisting of lower 4 and upper 5 parts, is made in the form of a gimbal with horizontal axes 10 and 11 intersecting, passing through the centers of rotation bearings 12 and 13 and intersecting the axis of rotation Ox. The distance h between the crossing axes is selected as large as possible, taking into account the overall and strength limitations imposed on the design parameters of the device. The platform 6 is made with part 14 rotatable relative to the vertical axis. The geometric certainty of the position of the product is defined by the basic coordinate system Oxyz of the product. In the process of measuring the product on the platform is installed in the position shown in figure 1, and in the position after the rotation of the platform with the product around the vertical axis Ox by 90 °.

The sensors 8, 8 ′ and 9, 9 ′ are installed with preliminary compression P _o deforming by half the linear strain d at the maximum allowable loading of the sensors.

The gaps Δ between the lower 4 and upper 5 parts of the hinge support are selected from the conditions of performance and balancing accuracy - with smaller gaps, the deviation of the product from verticality is smaller, which increases the accuracy of balancing, with large gaps the number of balancing cycles is reduced, since it is possible to measure at high rotation speeds products. Therefore, it is recommended that the initial balancing cycles be performed with large gaps, and the final cycles with smaller gaps. To set the gap values, for example, adjustable screw supports with micrometer nonius can be used. The values of the gaps Δ are in the range:

δ <Δ <d / 2,

where δ is the minimum deformation of the sensors corresponding to their sensitivity.

In rotation with a frequency ω on the bearing assembly 2, the table 3 is driven by a drive 15 connected to the shaft 16 of the bearing assembly by a coupling 17, for example, a bellows. The entire movable part of the device, including the table 3, the lower 4 and upper 5 parts of the hinge support and the platform 6 with the rotary part 14 are dynamically balanced relative to the vertical axis Ox.

The claimed method by means of the above device is as follows.

The product 7 is installed on the rotary part 14 of the platform 6 in a vertical position and in a static mode, without turning it, measure and eliminate the static imbalance within the accuracy capabilities of the sensors 8, 8 ′ and 9, 9 ′. To do this, according to the readings of the sensors determine the coordinates of the center of mass of the product ρ _y and ρ _z according to the formulas:

ρ _y = (P ′ ₉ -P ₉ ) r / mg;

ρ _z = (P ′ ₈ -P ₈ ) r / mg,

where: P ′ ₈ , P ₈ , P ′ ₉ , P ₉ - readings of sensors with corresponding indices;

r - the same distance of the sensors to the axis of rotation;

m is the mass of the product;

g is the acceleration of gravity.

The value of the radius ρ of the center of mass, the tangent of the angle α between the radius ρ and the axis Oy and the value of the static imbalance S _article defined in the static mode, are calculated by the formulas:

$$\begin{array}{l}\rho =\sqrt{{\rho }_y^2+{\rho }_z^2};\\ tg\alpha ={\rho }_z/{\rho }_y;\left(\mathrm{one}\right)\\ S_{\mathrm{from}t}=\rho \cdot m.\end{array}$$

The elimination of static imbalance can be carried out by traditional methods, for example, adding, removing, or moving balancing weights in correction planes. After eliminating the static imbalance in the static mode, measurements are made and the momentary imbalance and the static unbalance unrepaired in the static mode are measured and eliminated. To do this, the table with the product is rotated at a constant angular velocity ω and, using sensors 8, 8 ′ and 9, 9 ′, the reactions P ′ _8-1 , P _8-1 , P ′ _9-1 , P _{9-1 are measured} . Then rotate the upper part 14 relative to the lower part 6 of the platform by 90 ° and, accordingly, with respect to the sensors and again the table with the product is rotated at the same angular velocity ω and re-measured using sensors 8, 8 ′ and 9, 9 ′ reactions P ′ _8-2 , P _8-2 , P ′ _9-2 , P _9-2 . The equations of equilibrium of moments during rotations in both cases have the form:

$$\begin{array}{l}\left(P_{8-\mathrm{one}}^{\text{'}\text{'}}-P_{8-\mathrm{one}}\right)r-{\omega }^2{\rho }_{y}mH-J_{xy}{\omega }^2=0;\\ \left(P_{9-\mathrm{one}}^{\text{'}\text{'}}-P_{9-\mathrm{one}}\right)r-{\omega }^2{\rho }_{z}m\left(H-h\right)-J_{xz}{\omega }^2=0;\left(2\right)\\ \left(P_{8-2}^{\text{'}\text{'}}-P_{8-2}\right)r-{\omega }^2{\rho }_{z}mH-J_{xz}{\omega }^2=0;\\ \left(P_{9-2}^{\text{'}\text{'}}-P_{9-2}\right)r-{\omega }^2{\rho }_{y}m\left(H-h\right)-J_{xy}{\omega }^2=0,\end{array}$$

where: H is the distance from the center of mass of the product to the axis 10 of the bearings 12;

h is the distance between the axes 10 and 11;

J _xy and J _xz - centrifugal moments of inertia of the product;

ρ _y and ρ _z are the coordinates of the displacement from the axis of rotation of the center of mass of the product remaining as a result of the unbalanced static imbalance in the static mode.

From the resulting system of equations (2) determine the coordinates of the center of mass of the product ρ _y and ρ _z according to the formulas:

ρ _y = [(P ′ _8-1 -P _8-1 ) - (P ′ _9-2 -P _9-2 )] r / ω ² mH;

ρ _z = [(P ′ _8-2 -P _8-2 ) - (P ′ _9-1 -P _9-1 )] r / ω ² mH;

The value of the radius ρ of the center of mass, the tangent of the angle α between the radius ρ and the axis Oy and the value of the static imbalance S _article defined in the dynamic mode, are calculated by the formulas (1). After eliminating the calculated static imbalance, the table with the product is again rotated and the reactions P ′ ₈ , P ₈ , P ′ ₉ , P _{9 are} measured using sensors 8, 8 ′ and 9, 9 ′. The equations of equilibrium of moments with uniform rotation with the position of the coordinate system, as shown in Fig 1, have the form:

$$\begin{array}{l}\left(P_8^{\text{'}\text{'}}-P_8\right)r-J_{xy}{\omega }^2=0;\left(3\right)\\ \left(P_9^{\text{'}\text{'}}-P_9\right)r-J_{xz}{\omega }^2=0.\end{array}$$

From these equations, the centrifugal moments of inertia are determined:

J _xy = (P ′ ₈ -P ₈ ) r / ω ² ;

J _xz = (P ′ ₉ -P ₉ ) r / ω ² .

The momentary imbalance of the product can be eliminated by traditional methods, for example, adding, removing or moving a pair of balancing weights of mass m, set in two correction planes. The mass m and the tangent of the angle α between the cargo installation plane and the xOy plane are calculated by the formulas:

; $$m=\sqrt{{\left(P_8^{\text{'}\text{'}}-P_8\right)}^2+{\left(P_9^{\text{'}\text{'}}-P_9\right)}^2}/{\omega }^{2}RL$$

;

tgα = (P ′ ₈ -P ₈ ) / (P ′ ₉ -P ₉ ),

where: R is the distance from the axis of the Ox to the centers of mass of the balancing weights;

L is the distance between the correction planes.

If the initial imbalances of the product are large and at an acceptable angular velocity of rotation of the product, the dynamic reactions exceed the permissible measurement range of the sensors 8, 8 ′ and 9, 9 ′ with the maximum permissible gap Δ, the initial cycles of measuring imbalances described by equations (2) and (3), and balancing should be performed at lower angular velocities ω and large gaps Δ sufficient for normal operation of the sensors 8, 8 ′ and 9, 9 ′. To improve the accuracy of balancing in subsequent cycles, it is necessary to increase the frequency of rotation of the product up to the maximum permissible and reduce the gaps Δ up to the threshold of sensitivity of the sensors.

Practical parameters of the device for vertical dynamic balancing of a product with a low speed, for example, for a product weighing 1000 kg using tensometric force measuring sensors with a measurement range of 1.0 kg and a measurement error of not more than 0.5 g: rotation speed - 10-100 rpm min, the minimum achievable residual specific imbalance is 10 g · mm / kg.

Power supply of equipment located on a rotating table (sensors, transducers) is carried out using autonomous power sources - batteries. It is possible to supply power, for example, using rotating transformers or contact ring collectors. Reading measuring information from sensors on a rotating table is carried out wirelessly. For the transmission of measurement information, it is also possible to use rotating transformers and contact ring collectors.

Thus, the proposed method of vertical dynamic balancing of a product with a low speed due to additional measurements of dynamic reactions between the platform and the table with a changed mutual vertical position of the hinge of the central support and the product allows you to expand technological capabilities due to the additional ability to determine in a dynamic mode the static component of the imbalance, and the proposed a device in which the central articulated support is made in the form of a gimbal with horizontal horizontal axes crossing the axis of rotation, and the platform is rotatable relative to the vertical axis, it allows the most complete consideration and elimination of the dynamic imbalance of the product being balanced by eliminating, together with the moment component, the imbalance and the static component determined in the dynamic mode.

Claims (2)

1. The method of vertical dynamic balancing of the product, in which the product is rotated on a platform mounted on a central hinge support on a rotating table, and measure the dynamic reactions between the platform and the table, characterized in that they further measure the dynamic reactions between the platform and the table when the mutual the vertical position of the hinge of the central support and the product. 2. A device for vertical dynamic balancing of a product, comprising a housing mounted on it with the possibility of rotation on bearings relative to the vertical axis of the table, a central articulated support placed on the table, on which the platform for installing the product rests, the platform is connected to the table by means of sensors of dynamic reactions arising when the table is rotated with the product installed, characterized in that the central articulated support is made in the form of a gimbal with crossed horizontal axes E, intersecting the rotational axis of the section, and the platform is rotatable about a vertical axis.

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