design and development of ridge profile power weeder

DESIGN AND DEVELOPMENT OF

RIDGE PROFILE POWER WEEDER

COLLEGE OF AGRICULTURAL ENGINEERING AND TECHNOLOGY, VNMKV, PARBHANI

Presented by : Miss. More M.S.

Reg.No: 2012AE/42B

NECESSITY OF WEED CONTROL

• 30 % reduction in crop production.• To increase quality of product.• To minimize disease, health problems.• To feed increasing population.

WEEDING METHODS

• Hand weeding • Crop rotation • Biological weed control • Chemical weed control • Use of fire • Mechanical weed control

MATERIALS AND

METHODS

POWER REQUIREMENT

CONSIDERATIONS:

1. Specific draft of soil = 25N/cm2 (Sandy loam soil)

2. Speed of operation of weeder = 1 to 1.2 km/h

3. Total width of coverage of cutting blades = 400 mm

(Single ridge having 200 mm one side slanting length )

4. Depth of operation = 40 mm

5. Draft = 4000N

6. Power transmission efficiency of belt pulley = 70%

corresponding power requirement was calculated as:

Total power requirement (kW), = (Draft, N X Speed, m/s) Efficiency,% = (4000 X 1.2 X 1000) (3600 X (70/100) = 1.90kw

Therefore, an engine of 2.20 kW was selected as a power source for the weeder.

DESIGN OF ROTOR SHAFT

Maximum tangential force:

Where,Ks = Maximum tangential force, kgCs = Reliability factor (1.5 for non-rocky soils and 2 for rocky soils)Nc = Power of engine, hpȠc = Traction efficiency for the forward rotation of rotor shaft as 0.9Ƞz = Coefficient of reservation of engine power (0.7-0.8) = Minimum tangential speed of blades, m/s.

umin

umin

Tangential peripheral speed, umin can be calculated usingthe following equation:

Where, N = Revolution of rotor, rpm. R = Radius of rotor, cm. Take , N = 150rpm R = 5cm

Therefore, umin = 0.785m/s

and Ks = 290.2kg

The allowable stress on the rotor (τall) calculated by the following equation:

= 0.577×0.75×520 1.5 = 150 MPa = 1530.6 kg/cm2

Where, τall = Allowable stress on rotor shaft, kg/cm2

k = Coefficient of stress concentration (0.75) f = Coefficient of safety (1.5)σy = Yield stress, 520 MPa.

By substituting above values in the following equation, rotor shaft diameter was calculated as:

diameter of the rotor shaft was selected higher than the calculated value as 18 mm.

DESIGN OF CUTTING BLADE

Soil force acting on the blade:

Where,Ks = Maximum tangential force, kgCp = Coefficient of tangential forcei = Number of flangesZe = Number of blades on each side of the flangesne = Number of blades which act jointly on the soil by total number of blades for particular flange.By solving equation the soil force acting on the blade (Ke) was determined as 145.1 kg.

Stresses can be calculated by the following equations:

Where,σzg = bending stress, MPaτskt = shear stress, Mpaσzt = equivalent stress, MPa.By solving Equations the bending stress, shear stress and equivalent stress were determined as 85.40 MPa, 167.65 MPa and 346.0 MPa, respectively.

MACHINE COMPONENTS

Specifications of developed prototype weederSR.NO COMPONENT OVERAll DIMENSION MATERIAL OF CONSTRUCTION

1 Overall length 1220mm 25x25x4mmWidth 680mm M.S.squareHeigth 700mm Section

2 Soil cutting unitRotor shaft(2) Ф=18mm,200mm Rolled steelFlange(4) Ф=90mm,8mm M.SCutting Blade(6) 25x3mm M.S flatUniversal joint(2) Фi =22mm Forged Steel

3 Power Transmission

No. of transmission 2 Cast iron

No. of v-belt(B-Section) 2 Rubber

4 Handle Ф=25mm G.I.Pipe5 Wheel(3) Ф=150mm M.S6 Total weight 53kg -

PERFORMANCE EVALUATION

1. Weeding efficiency2. Plant damage3. Field capacity4. Performance index5. Field machine index

WEEDING EFFICIENCY

Where,

W1 = Number of weeds before weeding.

W2 = Number of weeds after weeding.

PLANT DAMAGE

Plant damage, %

Where,

q = Number of plants in a 10 m row length after weeding

p = Number of plants in a 10 m row length before weeding

PERFORMANCE INDEX

Where,

FC = Field capacity, ha/hr

PD = Plant damage, %

WE = Weeding efficiency, % P = Power, hp.

FIELD MACHINE INDEX

Where,

Tp = Total productive time, s

TO = Theoretical time, s

Tt = Time loss in turning, s

Fig. 4: Field evaluation of ridge profile power weeder

RESULT AND

DISCUSSION

Field performances of ridge profile power

weeder:Sr.No Performance parameter Result

1 Weeding efficiency, % 91.37

2 Plant damage, % 2.66

3 Average forward speed, km/h 1.33

4 Field capacity, ha/h 0.08

5 Performance index 192.34

6 Average field machine index, % 66.51

CONCLUSION The developed design of manually operated ridge profile

power weeder can be operated by 2.2kw engine with minimum plant damage.

C-type blades was found superior among the three types. Machine performance in sandy loam soil indicated that with

increase in soil moisture the weeding efficiency also increased. Optimal field parameters for C-type blade:1. soil moisture content = 15.26 ± 0.96%2. Mean weeding efficiency = 83.93%3. Plant damage = 1.77%4. Field capacity = 0.08ha/h5. Forward speed = 1.33km/h

Topic is open for discussion