Compensating combined working body of a road roller

Full Text

Introduction.
To develop the mechanical engineering and road industries, it is necessary to develop, design and manufacture modern high-performance equipment. One of the most popular machines in transport construction is road rollers. This machine is designed to compact the technological layers of roads in order to give strength and stability to the entire road structure. Currently, there is high competition among manufacturers of such machines. Models of such manufacturers as "HAMM", "BOMAG" (Germany), "DINAPAK" (Sweden), "SAKAI" (Japan) have proven themselves quite well in the market, have good reliability and high performance characteristics, but have a fairly high cost. In the price range, the best offers are put forward by Chinese manufacturers such as "XCMG", "Sany", "LiuGong", however, their reliability and performance characteristics are also somewhat lower. In Russia, there are well-known domestic manufacturers of road rollers: Rybinsk Plant of Road Machines (DM brand) and Raskat Plant (RW brand) in Rybinsk, which are comparable in performance to Chinese equipment, but can compete in price. The task of increasing the performance characteristics of the manufactured equipment to the characteristics of leading foreign manufacturers, while maintaining the cost of domestic road equipment, is relevant here. In the conditions of high competition and the import substitution program, it is necessary to provide road construction organizations with domestic mechanization tools and load the capacities of our machine-building enterprises.

Main part.
Based on the results of the analysis of the characteristics of the entire range of compaction equipment, both Russian and foreign manufacturers of road rollers, their advantages and disadvantages were identified [1, 2, 3]. One of the disadvantages of vibratory machines widely used for compaction of road construction materials is that during the vibration process the energy of the vibratory drum is spent on useful compaction work only in the half-period of oscillations when the vibratory drum moves "downward". In the second half of the period, the oscillating vibratory drum moves "upward" and does not produce useful compaction work on the material. Thus, more than half of the energy spent on excitation of vibration is wasted, which increases energy costs and reduces the share of useful work of the vibratory machine [1, 4].
From the point of view of increasing the share of energy spent by the roller on work on compaction of the material, it is necessary to reduce the "idle" component of the work on the movement of the vibratory drum "upward". This principle is implemented in the following design [4], a vibratory roller, contains a frame, and a working element consisting of two rollers of the main vibratory roller and an additional compensating roller, pivotally connected to each other by means of a double-arm lever through a slewing support device (Fig. 1). During the compaction process, during the half-period of oscillations during which the movement of the vibratory roller occurs upward, by means of a double-arm lever, through a slewing support unit (Fig. 2), the force is transmitted to the compensating roller, which moves downwards and exerts a useful effect on the compacted material and compensates for part of the lost energy of the main vibratory roller.

Figure 1 - General view of the road roller

Figure 2 - Slewing support device

The new design requires a preliminary calculation of the parameters of the presented machine. The dynamic scheme of the roller should take into account the nature of the connection of its rollers with the frame. In case of using special suspension elements and devices, their elastic and viscous properties should be considered in combination with the elastic-viscous properties of the rollers and the hinge.
The construction of a dynamic model of a road machine should be carried out taking into account the factors described above. Taking into account the absence of plastic deformations (wear) of the roller elements subject to force effects, and the invariability of their shape and size in the presence of elastic and viscous properties, modeling can be carried out within the framework of the Lagrangian formalism of classical mechanics [6, 7]. All elements of the roller diagram are represented as linear, possessing elastic and viscous properties, interacting massive bodies, considered within the framework of the concentrated parameter approach. Including the interaction forces of the roller units in the external periodic force of the machine's action on the compacted surface does not cause difficulties. Modeling the process of deformation of the compacted material during interaction with the compactor should be carried out taking into account the interaction of the roller units with each other and the reaction of the compacted surface to the working parts of the roller. The combined working element of the presented machine combines the possibility of more efficient use of the vibration energy of the vibratory drum with an increase in the productivity of the machine.
The scheme for modeling the impact on the supporting surface is shown in Figure 3.

Figure 3 – Calculation scheme

– distance from the center of mass of the main (vibratory) roller to the point of attachment to the roller frame;
– distance from the center of mass of the compensating roller to the point of attachment to the roller frame;
– vertical displacement of the main (vibratory) roller;
– vertical displacement of the compensating roller;
– vertical displacement of the roller frame due to the movement of the rollers
– reaction force (resistance) of the active region of the soil medium compacted by the main (vibratory) roller;
– reaction force (resistance) of the active region of the soil medium compacted by the compensating (static) roller;
– periodic driving force implementing the dynamic impact on the soil from the main (vibratory) roller.
The equation of motion of the system is constructed from the considerations that, under the action of a periodic force, the working element can perform rotational motion around the center of mass of the system and translational motion as a single whole together with the roller frame [8, 9, 10].
Let us find the equation of motion from the basic equations of dynamics
(1)
where is the resultant of the forces acting on the system,

is the total torque of the forces acting on the system relative to its center of mass
is the moment of inertia of the system during rotation relative to the center of mass, . Here and , respectively, are the distances from the center of mass of the system to the main (vibration) and compensating (static) rollers.

Assuming small values ​​of displacements relative to the radii of rotation during movement of the working element, we write the final form of the equations of motion
(2)
The solution of this equation together with the equations of motion make it possible to identify the effect of the distances of the centers of mass of the rollers from each other on the accumulation of plastic deformation by the compacted medium.
is the proportion of the roller frame mass per roller axis; is the roller mass; is the roller radius; is the periodic force of action.
Further consideration of the problem was carried out numerically in the Maple computer algebra environment.
As an example, we present the results of integrating the system (2) for the developed original working element with parameters corresponding to an average vibratory soil roller.
; ; ,
The sections of the soil environment interacting with the rollers of the working element will be considered as linear Kelvin-Voigt elements with constant rigidities and viscosities, respectively
, /
The parameters of the periodic force action were also selected in accordance with the recommendations and technical characteristics of average smooth-drum vibratory rollers:
, .
An illustration of how the parameters of the new working element affect the amplitudes of forced vibrations can be found in the graphical dependencies shown in Figure 4 for the displacement of the center of mass of the system, in the operating mode of a vibratory roller equipped with an original working element calculated for different positions of the support-slewing mechanism. The amplitude of the system's center of mass displacement indicates the amount of kinetic energy transferred to the roller frame, which essentially determines losses and undesirable effects on the operator.

a)

b)

c)
Figure 4 - Roller frame displacements during the periodic force action of 0.5 s at a) , b) , c) ,d

It is evident that the amplitude of this displacement changes, depending on the position of the support-slewing unit. Further numerical experiments for various values ​​of the roller parameters made it possible to construct a scheme for determining the rational parameters of a promising working element with the calculated values:
- distance between the centers of the rollers;
- mass of the main roller 1;
- mass of the compensating roller 2;
- frame mass per roller 1;
- frame mass per roller 2;
- amplitude of the periodic force of roller 1.
- radius of the main roller 1;
– radius of auxiliary roller 2;
Table 1
Linearized calculation scheme of parameters of prospective working element of vibratory roller
Calculation formulas for parameters of main roller (vibratory) Calculation formulas for parameters of auxiliary roller (compensating)

Calculation scheme parameters
For heavy rollers (18-22 t) For medium rollers (12-18 t) For light rollers (9-12 t)

Conclusion.
Based on the results of dynamic analysis conducted in the work, design features of original working element of road machine were determined, allowing to reveal its rational mass-dimensional characteristics. The obtained results allow to consider in the first approximation design parameters for creation and production of domestic high-performance road equipment for construction of highways and other transport facilities.
The research work is carried out within the framework of a grant from the Russian Science Foundation (RSF) and the Ministry of Industry and Scientific and Technical Development of the Omsk Region on topic No. 23-29-10010 “Development of road rollers to improve the efficiency of transport construction, taking into account the regional conditions of the Omsk Region”.

About the authors

Sergey Valerievich Savelyev

Email: saveliev_sergval@mail.ru

Vitaly Viktorovich Mikheyev

Omsk State Technical University

Email: vvm125@mail.ru

Candidate of physico-mathematical sciences, Associate professor

Ilya Konstantinovich Poteryayev

Federal State Budget Educational Institution of Higher Education «The Siberian State Automobile and Highway University»

Author for correspondence.
Email: ilya_poter@mail.ru
ORCID iD: 0000-0002-4350-2495

Candidate of Technical Sciences, Head of Department, Department of "Operation of Oil and Gas and Construction Equipment"

Russian Federation

References

Supplementary files