INCREASE OF OPERATING RELIABILITY OF THE TRAVEL WHEEL USING THE USE OF THE ELASTIC INSERTS

The aim of research is to substantiate the rational design of the travel wheel based on the determination of the dynamic forces arising from the movement of the freight carriage and the crane bridge. The research methodology is based on analytical methods for studying dynamic forces in the mechanism of movement of the cargo carriage of an overhead crane. The obtained solution of the three-mass dynamic scheme of the movement of the freight carriage. To verify the theoretical data obtained, an experiment was carried out on an overhead crane with a lifting capacity of 5 , span of 22.5 m, lifting height of 8 m, operating mode of 7 K. The study of the vibration state was carried out on the crane beam in the middle of the span, on the axis of the driven wheel of the crane trolley with an elastic insert and on the axis of the drive wheel of the crane trolley of a conventional design.

Crane wheels are the fastest wearing parts of a crane. A decrease in their durability leads to an increase in repair costs and crane downtime. Therefore, increasing the durability of crane travel wheels is an urgent task of modern crane construction. All designs of travel wheels are quite rigid and do not perceive shocks and distortions arising from the deviation of the rail track from the recommended values and lead to significant wear of the flanges and rails.

The analysis of the obtained solutions showed that when using a travel wheel with an elastic insert, the dynamic factors during the movement of the freight carriage decrease. Dependences are obtained for determining the dynamic forces arising from the movement of the travel crane wheel, taking into account the rigidity of the elastic ring, which is installed in the travel wheel. The analysis of the regularities of the formation of vibration signs at different points of the overhead crane structure is carried out. The proposed design and calculation method for a travel wheel with an elastic insert improves its operational reliability

of the movement mechanism can affect the dynamic processes in all crane mechanisms and even in the metal structure.
This gives grounds to assert that it is advisable to conduct a study to improve the operational reliability and durability of the travel wheel through the use of elastic inserts.
The aim of research is to substantiate the rational design of the travel wheel based on the determination of the dynamic forces arising from the movement of the freight carriage and the crane bridge.
To achieve the aim, the following objectives were set: -to substantiate the design of a crane travel wheel with an elastic insert and to determine the dynamic factors during the operation of the mechanism of movement of a cargo trolley based on a three-mass dynamic system, taking into account the elasticity of an elastic insert; -to conduct experimental studies of the formation of vibration signs that arise during the operation of the movement mechanism with travel wheels with elastic inserts and without inserts.

Methodology for the experimental study of the movement of the freight carriage taking into account the elastic insert of the travel wheel
The study of the crane travel wheel was carried out within the framework of the task of selecting and analyzing a more perfect wheel design, which will significantly increase its durability [14,15]. The proposed improved design of a travel wheel with an elastic insert leads to a decrease in stresses in the wheel and wear of the travel gear, including the flanges [16]. The crane travel wheel is under the influence of static and dynamic loads [17]. Static forces are classified as vertical and horizontal. Vertical ones arise from the weight of the load and the load carriage for the mechanism of movement of the load carriage and the weight of the bridge and load for the mechanism of movement of the overhead crane. Horizontal forces, as a rule, are the forces of friction between the travel wheel and the rail [18]. Dynamic loads arise during transient processes, as well as when the wheels are skewed and passing through the joints of the rail track [19,20].
The construction consists of several layers (Fig. 1), of which the outer layer is made of durable material, and the middle layer is a low-strength lightweight filler. The filler is not only of reduced weight, but has high strength and rigidity, which is explained by the high value of the moment of inertia of the entire wall. Compared to a single-layer skin, the moment of inertia can be increased many tens of times.
Taking into account the flexible suspension of the load, let's have a three-mass scheme (Fig. 2).
The drive mechanism for the movement of the load trolley is located, as a rule, in the middle of the trolley path. The movement to the drive wheels is transmitted by a transmission shaft. In a detailed study of the dynamics of the movement mechanism, it is possible to use a design model with three masses and two elastic ties. It is possible to reduce all the parameters to the chassis of the bogie and the load. Then let's obtain a scheme of gradual movement (Fig. 2). Fig. 2. Three-mass scheme of flexible load suspension: m 1 -mass of rotating parts (mass of the engine motor and other parts, mainly the motor clutch and brake pulley) m 2 -reduced mass of parts that move forward; m 3 -cargo weight; С 1 -coefficient of stiffness of the low-speed transmission shaft; C 2 -stiffness of another elastic connection Solve the system:

Mechanical Engineering
After solving system (1), let's obtain the differential equation: where ( ) The solution to equation (2) will be sought in the form: Coefficients А 1 , А 2 are determined using the initial conditions:

Mechanical Engineering
Let's find the coefficient: After this equation (6) takes the form: The equations of motion for the second and third masses will be: Let's find the efforts in elastic connections: A calculation was carried out for an overhead crane with a lifting capacity of 5 tons, a span of 22.5 m, a lifting height of 8 m, an operating mode of 7 K.
According to the results of calculations, the dynamic coefficient of a standard travel wheel is 1.65, and a travel wheel with an elastic insert is 1.1.

Research results of the formation of vibration signs taking into account the elastic insert of the travel wheel
To conduct an experimental study of vibration accelerations arising during the movement of the travel wheel, the Ultra-V-I complex was used. The general characteristics of the complex are summarized in Table 1.
The vibration measuring complex was located directly at the object of research -an overhead crane. The sensors were installed at the control points of the trolley and the crane and, using wires placed on the crane beam, were connected to an analog-to-digital converter, which, together with a computer, were located in the crane cabin (Fig. 3). The latter made it possible to exercise direct control over the operating modes of the crane (idling, lifting and moving loads of different weights at different speeds).

Fig. 3. Placement of the vibration measuring complex
The study of the vibration state was carried out in three control places: -on the crane beam in the middle of the span; -on the axis of the driven wheel of the crane trolley with an elastic insert (Fig. 4, a); -on the axis of the drive wheel of the crane trolley of a conventional design (Fig. 4, b). In accordance with the experimental research methodology, an analysis was made of the regularity of the formation of vibration signs at different points of the structure in the idling mode of the crane. That is, while the trolley is moving along the crane without load. At the same time, the modes of movement of the trolley with different speeds were considered. Analysis of the spectral composition of these vibrations shows that high frequencies with a peak of 120 Hz prevail in the spectra of vibration accelerations. On the beam, there is a pronounced short-band noise in the range of 30-80 Hz, the intensity of which increases with an increase in the speed of the trolley. Fig. 6, 7 show the registered signals and their spectral analysis for vertical ( Fig. 6) and axial (Fig. 7) vibrations on the axles of the driven and driven wheels. It should be noted that the driven wheel in this case is a modernized design and has elastic inserts. The level of vibration accelerations in the vertical direction on the modernized driven wheel at idle is almost 4 times less than the level of vibration accelerations on the drive wheel of a conventional design. The situation is qualitatively the same at two recorded speeds. With an increase in the speed of movement, an increase in the level of vibrations is observed, as on the rails and in the beam.
Vibration in the axial direction (Fig. 7) is lower. The tendency to reduce vibration accelerations on the driven modernized wheel is also preserved here, but in quantitative terms, the reduction in vibrations is smaller -within 50 %.

Mechanical Engineering
The level of vibration accelerations in the vertical direction on the modernized driven wheel at idle is almost 2 times less than the level of vibration accelerations on the drive wheel of a conventional design. The situation is qualitatively the same at two recorded speeds. With an increase in the speed of movement, an increase in the level of vibrations is observed.
Vibration in the axial direction ( Fig. 9) is lower. The tendency to reduce vibration accelerations on the driven modernized wheel is also preserved here, but in quantitative terms, vibration reduction is smaller -within about 70 %.

Discussion of the research results of the dynamics of the established movement of the freight carriage and the formation of vibration signs taking into account the elastic insert of the travel wheel
The substantiation of the design of a crane travel wheel with an elastic insert has been carried out. The dynamic factors are determined during the operation of the mechanism of movement of the freight carriage based on the three-mass dynamic system, taking into account the elasticity of the elastic insert.
Experimental studies of the formation of vibration signs that arise when the movement mechanism operates at different speeds, with travel wheels with elastic inserts and without inserts.
The generalized results of the RMS vibration acceleration in the vertical and axial directions on the modernized (with an elastic, rubber insert) and standard wheels (conventional design) are shown in Fig. 10, 11. The obtained results are explained by the fact that the proposed improved design of a travel wheel with an elastic insert leads to a decrease in the level of vibration accelerations in the vertical and axial directions on the modernized wheel, as well as wear of the travel gear, including the flanges. During the experiment, the modernized travel wheel was inspected after loading. Upon examination, no change in the elastic was found.
The article presents a new model of a travel wheel, which has significant advantages for its application in the mechanisms of movement of a crane cargo trolley and a crane. The calculations and experiments carried out have fully proved the feasibility of introducing such wheels on overhead cranes. The literature review showed that such a question has not yet been investigated by anyone.
In the future, it is necessary to conduct studies of the stress state of the elastic insert and the predicted durability of the travel wheel. It would also be advisable to use the strain gauge method during this pilot study.

Conclusions
Based on the results of determining the dynamic factors during the operation of the mechanism of movement of the freight carriage based on the three-mass dynamic system, taking into account the elasticity of the elastic insert, the dynamic coefficient was calculated. For a standard travel wheel, the dynamic coefficient is 1.65, and for a travel wheel with an elastic insert 1.1.
The results of an experimental study of the formation of vibration signs arising in travel wheels show that the use of an elastic insert significantly reduces their level. So the ratio of vertical vibrations from modernization of wheels is 45 %, and the ratio of axial vibrations from modernization of wheels is 39 %.