Tag Archives: mulcher

xxx J. Čedík, J. Chyba, M. Pexa and S. Petrásek
Influence of shape of cutting tool on pressure conditions in workspace of mulcher with vertical axis of rotation
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Influence of shape of cutting tool on pressure conditions in workspace of mulcher with vertical axis of rotation

J. Čedík¹*, J. Chyba², M. Pexa¹ and S. Petrásek²

¹Czech University of Life Sciences, Faculty of Engineering, Department for Quality and Dependability of Machines, Kamýcká 129, CZ16521, Prague 6, Czech Republic
²Czech University of Life Sciences, Faculty of Engineering, Department of Agricultural Machines, Kamýcká 129, CZ16521, Prague 6, Czech Republic
*Correspondence: cedikj@tf.czu.cz

Abstract:

Nowadays there is laid great insistence on work efficiency improvement. This effort also affects the construction of mowers such as mulchers. Mulching with a vertical axis of rotation is very energy demanding work operation mainly, due to high energy losses. These energy losses, but also the quality of work, are influenced by the airflow and associated conditions of pressure inside the workspace of mulcher. Airflow in the workspace ensures repetitious contact of the truncated forage crops with the cutting edge tool and thus ensures crushing of aboveground parts of plants. The paper deals with the influence of the cutting tool shape on the mulcher’s inside workspace pressure conditions with the vertical axis of rotation. The influence of the trailing edge angle and rake angle on the pressure profile in the mulcher’s workspace with dependence on the rotor speed was examined. Measurements were performed on a laboratory single rotor mulcher model. It was found that in the mulcher’s workspace the vacuum is formed by virtue of the rotary movement of the cutting tools wherein the vacuum increases with rotor speed. The maximum measured vacuum was about 2.4 kPa and from the centre of the rotor towards its circumference almost linearly decreases. Furthermore, it was found that with decreasing trailing edge angle and with increasing rake angle the maximum vacuum decreases. When reducing the angle of the trailing edge from 45° to 25° led to reduction of vacuum of about 0.3 kPa (12.6%).

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xxx M. Pexa, J. Čedík, F. Kumhála and R. Pražan
Comparison of mechanical and electric drive of mulcher
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Comparison of mechanical and electric drive of mulcher

M. Pexa¹*, J. Čedík¹, F. Kumhála² and R. Pražan³

¹Czech University of Life Sciences, Faculty of Engineering, Department for Quality and Dependability of Machines, Kamýcká 129, CZ16521, Prague 6, Czech Republic
²Czech University of Life Sciences, Faculty of Engineering, Department of Agricultural Machines, Kamýcká 129, CZ16521, Prague 6, Czech Republic
³Research Institute of Agriculture Engineering, Drnovská 507, CZ161 01, Prague 6, Czech Republic
*Correspondence: pexa@tf.czu.cz

Abstract:

The contribution is focused on comparison of mechanical and electric drive of mulcher with vertical axis of rotation by means of mathematical model. The mulcher has working width of 6 m and it is usually aggregated with tractor of minimal power of 150 kW. On the test plot the torque and power transferred trough the tractor PTO, fuel consumption and the production of gaseous emissions components were monitored. This field measurement served as a basis for modelling as well as measured complete characteristics of the combustion engine of the tractor John Deere 7930. As a main base for the modelling the record of real operation of the tractor with mulcher was used. Then, in the software product MathCad the operation of the tractor with mechanical and electrical drive of the mulcher was modelled. In the case of the electrical drive of the mulcher the tractor with internal combustion engine, connected to generator was taken into consideration. Due to overall lower efficiency of the electrical drive with generator, worse values of the fuel consumption and emissions production in comparison with mechanical drive were reached in case of electric drive. At hypothetical use of batteries (100% electro-powered tractor) and when the energy mix at Czech Republic is taken into consideration, it is possible to reach the quarter values of emissions production in comparison with combustion engine.

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xxx J. Čedík, M. Pexa and R. Pražan
Effect of rake angle and cutting speed on energy demands of mulcher with vertical axis of rotation
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Effect of rake angle and cutting speed on energy demands of mulcher with vertical axis of rotation

J. Čedík¹*, M. Pexa¹ and R. Pražan²

¹Czech University of Life Sciences Prague, Faculty of Engineering, Department for Quality and Dependability of Machines, Kamýcká 129, CZ165 21, Prague 6, Czech Republic
²Research Institute of Agriculture Engineering, Drnovská 507, CZ161 01, Prague 6, Czech Republic
*Correspondence: cedikj@tf.czu.cz

Abstract:

The contribution deals with the reduction of agriculture energy demands. For maintenance and treatment of permanent grassland areas, areas left fallow and put to rest the mulching in combination with other workflows (mowing, grazing) is advantageous procedure. As conventional impact grass cutting and chopping is energy demanding procedure, it is proper to reduce the energy demands of such device. In the paper the effect of shape of cutting tool, particularly the rake angle, on energy demands of mulcher with vertical axis of rotation is studied. The effect of cutting speed on energy demands is also verified. The measurement was performed using mulcher MZ 6000 made by Bednar FMT Ltd. with working width of 6 m and three rotors. During the measurement the test rides using the cutting tools with different rake angle and cutting speeds of 105m s-1, 89 m s-1 and 79 m s-1 were performed. The rake angle of cutting tools were chosen 0°, 15° and 25°. The test area was pasture with permanent grassland. During the measurement the torque and power, transferred through PTO to the machine, fuel consumption and GPS coordinates were measured. From each test ride the samples of grass matter were taken in order to determine the yield and moisture content. It was found that increase of the rake angle up to 25° and decrease of the cutting speed resulted in decrease of the power requirement of the mulcher.

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1380-1385 F. Kumhála, J. Chyba, M. Pexa and J. Čedík
Measurement of mulcher power input in relation to yield
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Measurement of mulcher power input in relation to yield

F. Kumhála¹*, J. Chyba¹, M. Pexa¹ and J. Čedík²

¹Czech University of Life Sciences, Faculty of Engineering, Kamýcká 129, CZ 165 21 Prague-6 Suchdol, Czech Republic
²Research Institute of Agricultural Engineering, p.r.i., Drnovská 507, CZ 161 01 Prague-6, Czech Republic
*Correspondence: kumhala@tf.czu.cz

Abstract:

Mulching is one of relatively energy-demanding operations in plant production. That is why the knowledge of mulcher power input is very interesting and can be used e.g. for mulcher design improvement etc. Field experiments were arranged in order to measure mulcher power input also in relation to yield. The field of about 1.25 ha area was harvested by mulcher MZ6000 produced by BEDNAR FMT Co. This machine has three rotors with vertical axis, working width 6 m and was aggregated with JD 7930 tractor. Power input was measured by torque dynamometer Manner MFI 2500 placed at tractor PTO shaft. Measured data were processed by A/D converter Labjack U 6 and saved. After the harvest, the samples of harvested material from area 6 x 1.65 m were weighted by hands on 102 places in almost regular grid. Average measured mulcher power input was relatively high, 76 kW, with peaks reaching up 145 kW. The yield of harvested material on experimental field was very unbalanced and varied from 0.6 to 13 tonnes per hectare. The amount of measured data allowed the creation of power input and yield maps. By comparing the results from power input and yield measurement it was found that power input significantly depended on the yield. Information of mulcher power input can be used also for harvested material yield mapping.

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46-52 J. Čedík,, M. Pexa, R. Pražan, K. Kubín and J. Vondřička
Mulcher energy intensity measurement in dependence on performance
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Mulcher energy intensity measurement in dependence on performance

J. Čedík¹,*, M. Pexa¹, R. Pražan², K. Kubín² and J. Vondřička¹

¹Czech University of Life Sciences, Faculty of Engineering, Department for Quality and Dependability of Machines, Kamycka 129, 16521, Prague 6, Czech Republic
²Research Institute of Agricultural Engineering, p.r.i., Drnovská 507, 16101, Prague 6, Czech Republic *Correspondence: cedikj@tf.czu.cz

Abstract:

Conventional impact grass cutting and chopping is energy intensive and therefore it is important to reduce energy demands of such a device. In the paper the energy demands of three-rotor mulcher with vertical axis of rotation was measured and analyzed in dependence on the mass performance of the mulcher. Different mass performance was achieved by different ground speed and yield of the grass cover. The measurement was performed on clover-grass meadow hay, from which the samples were taken and analyzed in order to determine the yield and moisture content of the vegetation. The results showed relatively high energy demands of the mulcher. In dependence on the mass performance of the mulcher it is necessary to deliver in average 10.4–22.6 kW m-1 of the width of the machine. Specific energy consumption varied in average from 3.35 to 6.34 kWh t-1 of the processed material and unit fuel consumption varied in average from 2.56 to 0.94 kg t-1.

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