Device for passive dynamic balancing of shot blast turbine rotor

Abstract

FIELD: shot blasting equipment.SUBSTANCE: rotors of working wheels of shot blasting turbines and means for reducing their vibration during operation. Under abrasive conditions, uneven wear of the blades occurs, which causes progressive operational imbalance of the rotor, increased vibration, and a reduction in the service life of the drive bearing assemblies. The shot blasting turbine device is equipped with at least one passive dynamic balancing unit, designed with the possibility of rotation together with the rotor and containing a closed annular cavity, inside which movable balancing elements are placed with the possibility of free movement along the circumference of the cavity under the action of centrifugal forces. Moreover, the connection along the mating plane of the hub and disk by means of a gasket, sealant or sealing ring ensures the sealing of the balancing annular cavity relative to the external abrasive environment of the shot blasting turbine. The annular cavity is closed with a lid and sealed against the external abrasive environment, and the inner surface of the cavity is made of wear-resistant material and / or provided with a wear-resistant coating.EFFECT: ensuring the reliable operation of the balancing unit in the conditions of the external abrasive environment of the shot-blasting turbine by sealing the annular cavity along the mating plane of the hub and the disk, which allows to maintain the possibility of free autonomous centrifugal displacement of the movable balancing elements along the circumference of the cavity and thereby ensure compensation for the operational imbalance of the rotor during operation without stopping the equipment.2 cl, 3 dwg, 2 ex

Description

[0001] The invention relates to mechanical engineering, specifically to shot blasting equipment for cleaning and hardening parts, and concerns means for reducing vibration in rotating components. More specifically, the invention relates to a device for passive dynamic balancing of the rotor of a shot blasting machine's impeller (turbine), designed to compensate for operational imbalances during operation.

[0002] Shot blast turbines are known to contain a rotor with blades mounted on an electric motor shaft. During manufacturing and repair, the required uniformity of rotation and acceptable vibration levels are ensured by static and dynamic balancing of the rotor assembly, including selection and sorting of blades by weight.

[0003] A prior art method for rotor balancing is known, according to patent RU 2010137714A, "Rotor Balancing Method." This method involves the step-by-step installation of rotor components, with intermediate balancing operations performed during assembly / repair to reduce the initial imbalance. However, this method is a pre-operational step and does not automatically compensate for imbalances that arise and change during rotor operation due to uneven wear, adhesion, or other operational factors. If operational imbalance occurs, the equipment must be shut down and the balancing performed again.

[0004] A turbine rotor balancing device is also known, according to patent RU 2407897, "Turbine Rotor Balancing Device," in which imbalance correction is accomplished by moving balancing weights using drive and control means. However, the presence of drive mechanisms and control elements complicates the design and reduces its reliability when operating in a shot blasting turbine, characterized by abrasive dust and impact loads, and does not provide the simplicity and autonomy required for compensating for progressive operational imbalance.

[0005] A drawback of existing technical solutions for shot blasting turbines is that during operation, the abrasive flow causes uneven wear on the blades, leading to changes in rotor mass distribution, progressive operational imbalance, increased vibration, increased dynamic loads on the electric motor bearing assemblies, overheating, and reduced service life. Restoring balance typically requires shutting down the equipment, dismantling it, and rebalancing it on a stand, which results in downtime and increased operating costs.

[0006] The technical problem is to create a means of compensating for the progressive operational imbalance of the shot blast turbine rotor during operation without stopping the equipment, ensuring reliable operation in an abrasive and impact-loaded environment, which is aimed at reducing vibration and increasing the service life of bearing assemblies and the interval between repairs.

[0007] The technical result of the invention consists in ensuring the reliable operation of the balancing unit in the conditions of the external abrasive environment of the shot-blasting turbine by sealing the annular cavity along the mating plane of the hub and the disk, which makes it possible to preserve the possibility of free autonomous centrifugal movement of the movable balancing elements along the circumference of the cavity and thereby ensure compensation for the operational imbalance of the rotor during operation without stopping the equipment.

[0008] The specified technical result is achieved in that the balancing unit is made in the form of a hub mounted on the rotor shaft, wherein in the hub on the plane of its mating with the rotor disk there is an annular cavity, inside which movable balancing elements are freely placed with the possibility of autonomous centrifugal movement along the circumference of the specified cavity, and the connection along the mating plane of the hub and the disk by means of a gasket, sealant or sealing ring ensures the sealing of the balancing annular cavity relative to the external abrasive medium of the shot-blasting turbine.

[0009] Brief description of design options and drawings

[0010] The invention is explained by drawings, where:

[0011] • Fig. 1 shows a general view of the rotor of a shot blasting turbine with a dynamic balancing system implemented in the hub (option 1).

[0012] • Fig. 2 shows a sectional view of the hub of Fig. 1, illustrating the arrangement of the annular cavity and balancing elements.

[0013] • Fig. 3 shows an alternative embodiment of the system in the form of a separate balancing unit installed on the rotor shaft (option 2).

[0014] In the preferred embodiment (Fig. 1, 2), the balancing unit is made integral with the hub (1) of the rotor. In the body of the hub, on the plane of its mating with the disk (2) of the rotor, an annular cavity (3) is formed. Inside the cavity (3), balancing elements (4), for example, metal balls, are placed with the possibility of free movement. When an imbalance occurs (for example, due to wear of the blade (5)) during rotation of the rotor (shown by the arrow), the balls (4), under the action of centrifugal force (Fc), move and group in a sector of the cavity (3) opposite to the imbalance vector (Fd), compensating for it.

[0015] In another embodiment (Fig. 3), the balancing unit (6) is a separate housing with an internal annular cavity (3) and elements (4). The unit (6) is mounted on the rotor shaft (7) coaxially with it, for example, between the hub (1) and the engine support, and performs the same autonomous compensation function.

[0016] IMPLEMENTATION OF THE INVENTION

[0017] Definitions of terms

[0018] • Rotor imbalance is a condition in which the main central axis of inertia of the rotor does not coincide with its axis of rotation, which leads to the generation of centrifugal force.

[0019] • Autonomous balancing is a process of imbalance compensation that occurs automatically without external control action or stopping the rotating unit.

[0020] • Balancing unit – a structural element of the system containing an annular cavity for accommodating movable balancing elements and intended for their kinematic connection with the rotor.

[0021] • Annular cavity – a cavity in the shape of a torus or annular channel, the internal geometry of which ensures free circulation of balancing elements along its entire perimeter.

[0022] The passive dynamic balancing device can be implemented in various design variations while maintaining the stated technical result—automatically reducing and maintaining rotor vibration during operation by compensating for operational imbalance. Preferred embodiments are presented below, with reference to the drawings.

[0023] Example 1 (integrated execution; Fig. 1, Fig. 2).

[0024] The shot blast turbine rotor comprises a hub (1) designed for mounting on a shaft (7) and a disk (2) with mounting locations for replaceable blades (5). An annular cavity (3) is formed in the hub (1) on the mating plane with the disk (2), forming an annular channel. The cavity (3) can be formed by machining (turning) or casting.

[0025] Cavity (3) contains movable balancing elements (4), such as balls with a diameter of 4–8 mm made of bearing steel (e.g., ШХ15) or other wear-resistant material. The cavity geometry is selected to ensure adequate clearance for the elements (4) to move freely around the circumference.

[0026] The annular cavity (3) is closed by a cover; in this particular case, the cover is a disk (2), which, together with the hub (1), forms a closed channel. The connection along the mating plane of the hub (1) and the disk (2) is performed in such a way as to ensure the sealing of the cavity (3) with respect to the external abrasive medium of the shot-blasting turbine (for example, by means of a gasket, sealant or sealing ring. The inner surface of the cavity (3) is made of wear-resistant material and / or is provided with a wear-resistant coating or an insert (movement / rolling track), designed to operate under conditions of impact-abrasive loads.

[0027] The approximate dimensions of the cavity (3) may be, for example: an internal radius of about 89 mm and an external radius of about 137.5 mm; the specified values ​​​​are given as an example and do not limit the invention.

[0028] Device operation (Fig. 1, Fig. 2).

[0029] When the turbine is started, the rotor spins up to its operating speed (e.g., approximately 3000 rpm). If an operational imbalance occurs (e.g., due to uneven wear of the blades (5)), the resulting centrifugal force vector of the imbalance causes a redistribution of the moving elements (4) around the circumference of the cavity (3). The elements (4) shift and group in a sector that forms a corrective balancing mass, creating a compensating centrifugal moment directed opposite to the rotor imbalance moment. Due to this, rotor vibration is automatically reduced and maintained at a reduced level during operation without the need to shut down the turbine for rebalancing.

[0030] Example 2 (modular implementation; Fig. 3).

[0031] The device is designed as a stand-alone balancing unit (6), mounted coaxially on the rotor shaft (7). The unit (6) is a housing (e.g., detachable from two halves), inside which an annular cavity (3) with movable balancing elements (4) is formed. The housing is equipped with a means of fixing on the shaft (e.g., set screws, a clamping sleeve, a keyed connection). The annular cavity (3) is closed with a lid and sealed against the external abrasive medium by the means specified above; the inner surface of the cavity (3) is made of wear-resistant material and / or equipped with a wear-resistant coating / insert. This design allows the device to be equipped with already operated shot blasting turbines without replacing the standard rotor.

[0032] The operating principle of the modular design is similar to example 1: when an operational imbalance occurs, the moving elements (4) are autonomously redistributed around the circumference of the cavity (3), forming a corrective balancing mass and reducing vibration.

[0033] Means and methods of implementation:

[0034] – Balancing elements (4): can be made in the form of balls, rollers or other rolling elements, as well as in the form of bulk elements made of heavy wear-resistant material (for example, hard alloys), provided that they are free to move around the circumference of the cavity (3) under the action of centrifugal forces.

[0035] – Materials and wear resistance: elements (4) and the cavity surface (3) are made of wear-resistant materials (hardened steel, ceramics, hard alloys) and / or provided with a coating (e.g. nitride coatings) or a replaceable track insert.

[0036] – Sealing: the cavity (3) is sealed against the external abrasive environment by means of gaskets, sealants, and sealing rings, selected based on the design of the unit and the operating mode.

[0037] – Manufacturing: The hub (1) with the cavity (3) or the unit housing (6) are manufactured using casting and / or machining methods. After assembly, the unit / rotor can be statically and / or dynamically balanced to eliminate process imbalances.

[0038] The device's effectiveness was confirmed by bench tests on a rotor weighing approximately 25 kg with blades weighing approximately 0.6 kg, mounted at a radius of approximately 122 mm. An artificial imbalance was created by installing sets of blades with a mass difference Δm ranging from 2 to 30 g. Vibration velocity at the electric motor supports was measured in two cases: without the device and with a device containing 15 steel balls with a diameter of 6 mm (total mass approximately 13 g).

[0039] For the worst case (Δm = 30 g; imbalance of approximately 3660 g cm), the vibration velocity without the device reached approximately 18.9 mm / s, and with the device installed, it decreased to approximately 8.9 mm / s, which corresponds to a reduction of more than 50%. These results confirm the achievement of the declared technical result. The working range of parameters providing a compensation margin can be achieved by placing 10 to 40 balls with a diameter of 4–8 mm in a cavity (with a total mass of approximately 9–35 g); the values ​​​​given are examples and do not limit the scope of legal protection.

Claims

1. A device for passive dynamic balancing of a shot-blasting turbine rotor, kinematically connected to the rotor shaft, characterized in that the balancing unit is made in the form of a hub mounted on the rotor shaft, wherein an annular cavity is formed in the hub on the plane of its mating with the rotor disk, inside which movable balancing elements are freely placed, made with the possibility of autonomous centrifugal movement along the circumference of said cavity, wherein the connection along the mating plane of the hub and the disk by means of a gasket, sealant or sealing ring ensures the sealing of the balancing annular cavity relative to the external abrasive medium of the shot-blasting turbine.

2. The device according to paragraph 1, characterized in that the balancing elements are made in the form of balls made of wear-resistant material.

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