EXPERIMENTAL RESEARCH ON VIBRATIONAL DIGGING-UP OF SUGAR BEET

The conditions, required for the technological process of beet harvesting, are ensuring the performance, decreasing the energy losses and increasing the quality of the harvested products. As for beet harvesters, the required condition of ensuring the quality of performing the technological process is avoiding the damage to crop roots while they are dug up, rst and foremost. Therefore, there is a need to investigate the process of vibrational digging-up and to use its results to determine kinematic and constructive parameters of the digging-up working tools on condition of avoiding damage to the crop roots.


INTRODUCTION
The conditions, required for the technological process of beet harvesting, are ensuring the performance, decreasing the energy losses and increasing the quality of the harvested products. As for beet harvesters, the required condition of ensuring the quality of performing the technological process is avoiding the damage to crop roots while they are dug up, ¿ rst and foremost. Therefore, there is a need to investigate the process of vibrational digging-up and to use its results to determine kinematic and constructive parameters of the digging-up working tools on condition of avoiding damage to the crop roots.
The technological process of vibrational digging-up of sugar beet has spread in many sugar beet-sowing countries. Many years of using this process demonstrated a number of its advantages compared against other methods of digging-up. Therefore, this technological process requires further detailed analytical and Substantial theoretical research on the process of vibrational digging-up of crop roots was done in the works [1][2][3][4], but only the works [5] and [6] present some experimental results of the impact interaction of pendulum impact testing machine and a crop root. The analysis of scienti¿ c literature [7][8][9][10] demonstrated that quality indices of digging-up sugar beet from soil are paid considerable attention in Europe. As stated above, there have been scarce experimental researches on the process of vibrational digging-up of sugar beet from soil, therefore, this topic is urgent for sugar beetgrowing industry, as this research can allow improving the most energy-consuming technological process.
The aim of the research is the experimental determination of rational parameters and modes of the vibrational digging-up working tool to ensure the required quality of conducting the technological process of digging-up sugar beet from soil.

MATERIALS AND METHODS
A new model of the vibrational digging-up working tool was designed for experimental research on the process of vibrational digging-up of sugar beet from soil which was deemed to ensure quality extraction of crop roots from dry and solid ground. The construction design of the vibrational digging-up machine is protected with the Patent of Ukraine for an invention [11] Fig. 1.
The digging-up machine consists of digging-up blades (1), installed on the ends of the mounts (2), which are connected via suspension brackets (3) to the drive mechanism (4) of the mentioned blades (1) to obtain the vibrational movement. The mechanism (4) has a device, which can be used to set (regulate) the frequency and amplitude of the vibrational movements of blades in a wide range of values (the frequency is regulated from 8.5 to 20.3 Hz, the amplitude -from 8 to 24 mm). The suspension bracket (3) of the mounts (2) was equipped with an additional hinge which allows for free movements of coupled mounts (2) in a small range in the longitudinal-transversal plane. This ensures the automatic installation of blades (1) during the translational movement of the vibrational diggingup machine.
The general view of the designed vibrational diggingup working tool is presented in Fig. 2.   Fig. 1. The construction and technological scheme of the vibrational digging-up machine: 1 -a digging-up blade; 2mounts; 3 -mechanism of regulating the distance between blades; 4 -vibrational drive mechanism with the mechanism of regulating the amplitude and the frequency of blade vibrations; 5 -guide pins The experimental device (Fig. 3) consists of the frame (11), bearing on posterior (2) supporting and front (3) copying wheels. The front part of the frame (11) has the installed vibrational digging-up working tools (4), formed by digging-up blades (8), set on the mounts (9). The posterior necked part of blades (8) has a beater (5) with a 4-blade beater transporter (6) behind it. The vibrational digging-up working tools (4) are connected to the drive mechanism (7) for oscillatory movements with a wide range of amplitudes and frequencies.
To determine the energy-force characteristics, a tenzometric traction link was attached to the device for simultaneous measurement of the horizontal and vertical components of the traction effort on the towed device with a wheeled tractor (1). Foil tenzometric sensors were installed on the mounts (9) to determine the ef- Fig. 3. The scheme of the ¿ eld experimental device to investigate the vibrational digging-up working tools: 1 -a wheeled tractor; 2 -posterior supporting wheels; 3 -front (copying) wheels; 4 -vibrational digging-up working tools; 5 -beater; 6four-blade beater transporter; 7 -drive mechanism of vibrational digging-up working tools; 8 -digging-up blades; 9 -blade mounts; 10 -tape roll; 11 -frame EXPERIMENTAL RESEARCH ON VIBRATIONAL DIGGING-UP OF SUGAR BEET forts of the interaction between the blades (8) and soil. The drive of all the working tools of the experimental device was ensured by the power take-off shaft of the wheeled tractor (1), class 1.4. To de¿ ne the angular velocity, the steering torque and the power, transmitted to the working tools, an electric joint dynamometer was installed between the power take-off shaft of the tractor (1) and the drive shaft of the working tools of the experimental device. The general view of the experimental device during ¿ eld experimental research and that of the vibrational digging-up working tools under investigation is presented in Fig. 4. A movable tenzometric station, installed on a vehicle, was moving along the laboratory ¿ eld device during the experimental research.
During the work of the experimental device, the digging-up blade (8) takes a complicated load, estimated by the value of the bending motion of its mount (9) with the installed tenzometric sensors. A track-measuring wheel is attached to the frame to determine the velocity of the experimental device.
The registration of tenzometric indices of the investigated parameters within the energetic estimation of the work of vibrational digging-up machines was conducted using the movable tenzometric laboratory ChEK-1 (based on UAZ vehicle) which was moving along the experimental device during the experiments (Fig. 4,  ɚ). This laboratory allows measuring, registering and demonstrating the average values of power and velocity parameters via six independent measuring channels immediately after the experiments.
The cleaning and transporting working tools of the beet harvester were disconnected from the drive mecha-nism. A device for stripping the tape to collect the sugar beet, dug up from soil, in order to estimate the quality of their extraction in the ¿ eld work was installed behind the vibrational digging-up machines. The running depth of the digging-up machine in soil was controlled using the measuring device.
The determination of the agrotechnical indices of the experimental ¿ eld was conducted according to the general method and the method of the Ukrainian Research Institute of Forecasting and Testing of Equipment and Technologies named after Leonid Pogorilyi [12][13][14][15].
To determine the indices of agrotechnical evaluation, three standard plots, 20 m long and 2.7 m wide, i.e. having the width of six rows, were indicated along the sugar beet ¿ eld.
The thickness of weeds in the plot was determined by laying the rectangular frame of 90u111 cm (the area of 1 m 2 ) on two adjacent rows in ¿ ve repeats along the diagonal of the plot. All the weeds were counted within the rectangular frame and separately in the 20-cm-wide stripe of the row zone.
Prior to the experimental research, according to the method of determining the quality of beet harvesters [5] the following physical and mechanic properties of crop roots were determined: maximal diameter of a crop root; root length; weight of one root; distance between roots in the row; width of interrow distances; height of crop roots relative to the soil surface; deviation of crop roots from the relative axis line of the row.
The results of experimental research were processed according to the known method of statistical processing of experimental data [12,14,16] with further pre- Field testing of the beet harvester was conducted using the method of a multifactor experiment, which was described in [12][13][14][15].
The analysis of scienti¿ c literature, theoretical studies and previous testing of the machine were used to determine the rational ranges of factor changes, which have the most considerable impact on the quality of digging up crop roots from soil. Therefore, the velocity of the experimental device was set in the range of 1.3...2.55 m/s, the running depth of the digging up blades in soil À uctuated in the range of 0.06...0.12 m, the frequency of the working tool oscillations -8.5…20.3 Hz. The listed factors are independent, thus it is possible to change their values regardless from one another.
A complete three-factor experiment on investigating the impact of the mentioned factors on the quality indices of work was conducted with the corresponding standard matrix.
The impact of three factors on the quality indices of work was described using the results of processing the data of experimental research in regression equations in the form of a polynomial of degree 2: After the matrix of experiment planning was realized on the experimental device, the coef¿ cients for variables were de¿ ned using Statistica 6 program.

RESULTS AND DISCUSSION
During the experiment the agricultural background of the experimental plot had the following parameters: soil type -heavy clay loam, soil solidity -3.8.. The results of experimental research demonstrated that the increase in the frequency of working tool oscillations leads to the decrease in the loss of crop roots with a slight increase in the degree of crop roots in most cases.
The equation of the regression of the dependence between the losses of crop roots (Y 1 ) and the frequency of working tool oscillations (ɏ 1 ), running depth of the working tools in soil (ɏ 2 ) and the velocity of the translational movement of the vibrational digging-up machine (ɏ 3 ) is as follows: with the squared correlation coef¿ cient (squared multiple correlation) R 2 = 0.789; multiple correlation coef¿ cient R = 0.888; standard deviation S r = 0.508. For this type of function, regression coef¿ cients are insigni¿ cant for factors X 3 and X 1 X 3 .
The obtained model was used in the Statistica 6 application to build the surface of the response of crop root loss due to the frequency of oscillations of the working tool and its running depth in the soil for the velocity values of the translational movement of the digging-up machine 1.3; 1.75; 2.1; 2.55 m/s and their two-dimensional cross-sections were obtained (Fig. 5).
It was also important to investigate the dependence of the crop root losses on the solidity and humidity of soil during the vibrational digging-up. The beet harvester was tested at the frequency of the working tool oscillations of 8.5 Hz. The study of the loss of sugar beet losses depending on the velocity of the translational movement (X 1 ) and the running depth of the working tools (X 2 ) was also studied under different working conditions.
The following regression equation was obtained for the soil solidity of 3.8 MPa and its humidity of 8.0%: at R 2 = 0.950; R = 0.975; S r = 0.454.
The model obtained was used to build the response surface and its two-dimensional cross section (Fig. 5).
As seen from the obtained charts (Fig. 5), the losses increase with the increase in the velocity of the translational movement of the digging-up machine and decrease with the increase in the running depth in soil. This is explained by the fact that the higher velocity of the translational movement of the digging-up machine is, the fewer crop roots are taken by the working tool (the frequency of 8.5 Hz provides for this capture less with the increase in the translational velocity), the more crop roots remain either not captured or broken in the tail part. It is clear that the smaller the running depth of the digging-up machine in soil is, the higher is the level of breaking the tail part of crop roots or absence of their capture, which allows for higher losses. When EXPERIMENTAL RESEARCH ON VIBRATIONAL DIGGING-UP OF SUGAR BEET the digging-up machine moves at a higher depth, the impact of the translational velocity on the value of the crop root losses decreases due to breaking the tail part at a higher depth, thus this loss is smaller in percentage and less dependent on the velocity of the translational movement of the digging-up machine. The loss is minimal for the running depth of 0.11 m in soil.
The following regression equation was obtained for the soil solidity of 2.0 MPa and its humidity of 20.0%: at R 2 = 0.869; R = 0.932; S r = 0.674.
The graphic presentation of the losses of crop roots depending on the velocity of the translational movement of the digging-up machine and its running depth in soil under these conditions is presented in Fig. 6.
As seen from the presented chart (Fig. 6)  The agrotechnical indices of the ¿ eld plot, where experimental research was conducted to de¿ ne energy parameters, are presented in the Table. The investigation on the energy parameters of beet harvester in ¿ eld conditions was conducted by reading the values of tenzometric sensors under different working modes of the machine and different parameters and working modes of the vibrational digging-up tools. The graphic curves of energy-power characteristics of the vibrational digging-up working tool depending on the velocity of its movement are presented in Fig. 7. Characteristics of a crop: deviation of crop roots from the theoretical axis of the row, %: 0 ± 10 ± 20 ± 30 ± 40 mm and more location of crop root heads relative to the level of soil surface, %: -over -30 mm -from -20 to -30 incl.
-over +60 to +80 mm incl.  4.0 Winter wheat, inter-row tillage As indicated in [4], when the vibrational digging-up tool is used, the tractive resistance decreases 2.5…3.5 times compared to the resistance of the passive disk digger. Here, the resistance of the vibrational diggingup machine increases less intensively with the increase in the velocity of the translational movement compared to that of the passive disk digger, and even more sothat of the passive blade digger, which is proven by the experiment results.
When the towing force N -curve 3, is calculated along with the power on the drive mechanism of the vibrational digging-up working tool N pto -curve 4, the graphic curves are built to demonstrate that N and N pto of the vibrational digging-up working tool change from 4.0 to 7.0 kW. We built separate graphic curves for the dependence of the power, required for the drive mechanism of the oscillations of the vibrational digging-up working tool, on the velocity of the movement and the running depth of the digging-up blades in soil (Fig. 8) and on the velocity of movement and frequency of oscillations (Fig. 9).
As seen from the curves (Fig. 8), the lowest power, used for the drive of the vibrational digging-up working tools to the oscillatory movements, is present at the frequency of 8.  The velocity of the translational movement of the digging-up machine in the range of 1.3…2.1 m/s meets the agrotechnical requirements in terms of damage to crop roots (not more than 10% are acceptable), but the velocity of 2.55 m/s does not meet these requirements.
It was found that the mass of the damaged crop roots depends on the solidity and humidity of soil considerably. For instance, at the solidity of 2 MPa and humidity of 18 % it is in the range of 3.0…6.2 %, and at the solidity of 4 MPa and humidity of 8 % -in the range of 8.0…13.0 %.
The application of the vibrational digging-up working tool allows achieving the 2.5...3.5-fold decrease in the relative energy consumption of harvesting compared to the application of the passive disk digger, and even more so -the passive blade digger. It was established that the change in the velocity of the translational movement of the digger conditions the increase in the towing effort in a small range, and the change in the rotational moment on the power take-off shaft at the change in the velocity of the translational movement in the range of 0.5...1.4 m/s is in the range from 50 to 70 newton-meter.
The smallest power, used for the drive of the vibrational digging-up working tools (providing oscillatory movements), corresponds to the frequency of oscillations of the working tool of 8.5 Hz and the running depth of 0.06 m in soil. Considering that the minimal losses and damage of crop roots take place at the running depth of the digging-up machine of 0.09 m in soil, it is more rational to have the running depth of the digging-up machine of 0.08…0.10 m and the frequency of oscillations of the working tool of 10…18 Hz.