THE  ABSTRACT OF THE MASTER'S GRADUATION WORK

Lysenko Oksana

Theme of the graduation work:

"Mathematical modeling of loadings in variable-frequency electric engines of double mover cutter loader moving mechanism"

My scientific instructor: professor of the mining machines department Kondrakhin Vitaliy Petrovich

 

 

On a combine UKD300 is used double mover cutter loader moving mechanism with variable-frequency electric engines. The operation of combines UKD300 has revealed necessity of loading characteristics increase of the moving mechanism. Actual total load effort of two drivers in some cases is much less than rating value. One of the main reasons it is non-uniform loading distribution between is frequency - are adjustable by asynchronous electric drives. On the special stand on "Gorlovskiy mashinostroitel" the experimental researches of a combine UKD300 were spent as a result of the researches analysis the basic laws of dynamic processes formation in drives of the moving mechanism are established. In all registered fluctuation modes of the moments in left and right drives occur practically in a gas mask both on high and on low-frequency components. Therefore the essential distribution of loading non-uniformity between drives left and right drivers is formed. At the separate moments of time most loaded driver provides up to 96 % general of load effort. The job of a drive in a generating mode is on occasion possible.

On pictures of the twisting moments and shaft rotation frequencies it is necessary to allocate first of all high-frequency component, which period is caused by the period of a tooth of an asterisk contact with bobbin rack. The presence of such component allows to make a conclusion that the non-uniformity kinematics and power parameters is called by imperfection of the gearings geometrical characteristics "a star-bobbin" and "a wheel-star" in three-element driver.

        

MATHEMATICAL MODELING

 

For convenience of the analysis of a gearing kinematics picture is entered into consideration given kinematics r_кi(φ_кi)  radius of any from i three-element driver, which physical sense is clear from expression:

                                      (1.1)

Where  ω_кi - angular speed of a wheel of i- three-element driver;

V_П(f_с) - moving speed of a combine dependent from frequency of a having network f_с;

φ_кi - corner of turn of a wheel i - three-element driver.

For experimental modeling was used 3D model created through the automated designing modern programs.

Picture 1. - 3D model for experimental modeling

 

The solid-state modeling given kinematics of radius at interracial distance of 147 mm was carried out by fixation of the following parameters: an axis linear moving of a wheel and its corner of turn.

Given kinematics radius:

 But    ,                                                                        

Where  - moving of an axis of a wheel for an interval of time;

  - angle of turn of a wheel for an interval of time.

Thus .

The experiment on modeling given kinematics radius at transition of a star on new bobbin rack with interracial distance 147 mm was carried out at increase of distance between two bobbins from 100 mm up to 104 mm, that simulated transition of a star on new bobbin rack.

On the basis of this diagram it is possible to make a conclusion that at transition on new bobbin rack (for interracial distance of 147 mm this transition was carried out at φ_к=74,4º) gearing of a star period with previous bobbin decreases, and the gearing of a star period with first bobbin of new rack is increased.

 

CONCLUSIONS ON EXPERIMENT

 

On the basis of the carried out experimental researches it is possible to make the following conclusions:

Given kinematics radius is periodic function, which period corresponds to the gearing of a star period with bobbin;

- On the diagrams of given kinematics radius the sharp change of meanings is precisely traced which is caused by change of contacting pair in gearing "a wheel-star";

- Increase of interracial distance in gearing "the star-bobbin" renders influence on growth of difference meanings given kinematics radius at transition with one bobbin on another (at interracial distance of 147 mm difference makes 6 mm);

- On the basis of the diagrams describing process of passage of a joint between rack bobbins, it is possible to make a conclusion that at transition on new bobbin rack the gearing of a star period with previous bobbin (approximately on 45 % for interracial distance of 147 mm) decreases, and the gearing of a star period with first new rack bobbin is increased by the same meanings;

- The distinctions in character and numerical meanings between the data received in result of experiment and solid-state modeling, are explained to  that the solid-state modeling does not take into account deterioration of bobbin rack while in service, and also elastic deformations arising in elements three-element driver.

 

CONCLUSIONS

 

In double mover cutter loader moving mechanism with variable-frequency electric engines is possible which will result in total loading decrease of the mechanism characteristics. For elimination of this lack it is possible to offer a number of measures:

- decrease to a minimum (1-2 mm) backlash in return captures, thus for exception of support jamming are necessary to provide additional degrees of freedom in units of fastening rack to the conveyor and return captures of a combine to its case;

- to spend a engines selective complete set for each combine feeders;

- to enter into a mechanism design of moving the leveling mechanism ensuring reducers mechanical connection of both engines;

- to improve algorithm of electric motors management, having provided increase of a having voltage at occurrence of a difference between engines feeder currents (at the increase expense of the maximal rotating moment it is possible to compensate loading effort shortage caused by engines non-uniform loading, however thus it is necessary to arrange on hardening of reducer’s and driver’s design).