Combine Harvester PDF
Document Details
![FastPacedWichita](https://quizgecko.com/images/avatars/avatar-15.webp)
Uploaded by FastPacedWichita
Tags
Related
- combine 1.pdf
- Quadratic Equations PDF
- Bihar State Electronics Development Corporation Ltd. Data Entry Operator Exam PDF, 2019-2020
- Manufacturing Good Manufacturing Practices (GMP) PDF
- C05A-AENGR1105-Harvesting, Threshing, And Other Postharvest Machineries-PPT PDF
- Climate Change Stressors in Arctic Alaska PDF
Summary
This document provides an overview of combine harvester systems, specifically focusing on harvesting paddy. It details the different components of a combine harvester, including their functions and operational aspects. The document also discusses the advantages and disadvantages of using combine harvesters in agricultural settings.
Full Transcript
Harvesting of Paddy Combine harvesting systems The combine harvester combines all operations: cutting the crop, feeding it into the threshing mechanism, threshing, cleaning, and discharging grain into a bulk wagon or directly into bags. Straw is usually discharged behind the combine in a windrow....
Harvesting of Paddy Combine harvesting systems The combine harvester combines all operations: cutting the crop, feeding it into the threshing mechanism, threshing, cleaning, and discharging grain into a bulk wagon or directly into bags. Straw is usually discharged behind the combine in a windrow. Tractor-drawn combine harvester Self propelled combine harvester Cutter Bar Width: 4 feet Rated Feed Capacity (kg/s): 1.5 kg/s Cutter Bar Width: 6-8 feet Engine Output And Rotating Speed Power Output: 35 to 70 HP (HP/rpm): 22HP / 27HP/ 2200 r/min Cutting capacity: 1.5 acres/hour Track combine harvester Harvesting of Paddy Combine harvesting systems Advantages: 1. Reduces labor requirement and drudgery 2. Scheduled operation avoiding adverse conditions (untimely rain, storm, fire hazard, etc) 3. Time saving 4. Provides opportunity for early harvest, and time for seedbed preparation for next crop Disadvantages: 1. High initial investment cost 2. Difficult to maneuver in small and irregular shaped field 3. Loss of straw 4. High operational and repair cost Harvesting of Paddy Separating Unit Threshing Unit Header Unit Cleaning Unit The yellow stream is the crop, orange is chaff, blue is forced air, and red is the grain. 1) Reel 6) Threshing drum 12) Bottom sieve 18) Driver's cab 2) Cutter bar 7) Concave 13) Tailings conveyor 19) Engine 3) Header auger 8) Straw walker 14) Rethreshing of tailings 20) Unloading auger 4) Grain conveyor 9) Grain pan 15) Grain auger 21) Impeller 5) Stone trap 10) Fan 16) Grain tank 11) Top Adjustable sieve 17) Straw chopper Harvesting of Paddy Reel Hold and guide the crop towards the cutter bar until it has been cut and lay it on cutter bar platform. Diameter ranges between 1-1.5 m Hydraulic attachments are used to adjust the height and clearance from cutter bar Types: bat type (good for standing crop with small size grain, shattering loss due to slap) pick-up type/tyne type (also benefits the lodged crop) Vertical adjustment (height of cut 7.5-90 cm) Horizontal adjustment (distance between cutter bar & reel, should be high for lodged crop, 230-300 mm ) Harvesting of Paddy Reel Reel speed should be It should run fast without shattering the grain or throwing the cut crop out of the cutter bar Should move the harvested crop smoothly over the header platform In general same or little more than forward speed of combine Reel Index ๐๐๐๐๐โ๐๐๐๐ ๐ ๐๐๐๐ ๐๐ ๐กโ๐ ๐๐๐๐ ๐ ๐๐๐ ๐๐๐๐๐ฅ = ๐น๐๐๐ค๐๐๐ ๐ ๐๐๐๐ ๐๐ ๐กโ๐ ๐๐๐๐๐๐๐ Optimum range: 1.25-1.5 for upright crops Reel index for lodged crops is less compared to upright crops Harvesting of Paddy Platform auger Due to spiral movement of auger conveyer, crop is collected from the entire length brought to center. Prongs take the crop and pushes them to conveyer chain of feeder assembly. Vertical height adjustment is done to maintain the clearance between auger conveyer flight and header platform, generally 20 mm. Diameter of the auger ranges from 40-60 cm Flight Prongs Platform auger Harvesting of Paddy Feeder conveyer To convey the harvested crop to threshing unit Set of sprocket fixed on two shaft. Serrated mild steel slats are fitted across chain length, which restricts the crop to roll back and convey efficiently Harvesting of Paddy Threshing Unit Removal of grain from ear head or pods Works on impact force on crop by the rotating threshing cylinder, resulting in separation of grains from ear head Rubbing action between crop layers over each other while passing through constricted space between concave and cylinder Types: raspbar, 6-8 in no. (wheat), spike tooth (rice) Threshing Factors affect threshing effectiveness Cylinder Peripheral speed of cylinder Clearance between concave & cylinder Number of rasp-bar or spike tooth Type of crop Moisture content of crop Feed rate Concave Harvesting of Paddy Straw walker Separate the grains from long chaff. The grains drop on oscillating grain pan and throws out long straw out of machine. Speed of straw walker is 200 cycles/min Number of straw walker varies from 4-7 in number and kept in cascade steps to improve the separation Length of straw walker is 4 m. Speed of straw walker is 190-200 rpm. Harvesting of Paddy Grain cleaning unit Separate and clean the grain from straw. Returns the unthreshed ear heads to threshing unit for re-threshing Throws out the chaff dust and short straw out of the machine Consists of 2-3 oscillating sieves and blower having 4-6 blades. Tailing is the unthreshed ear heads that are heavy to be blown out of machine and large enough to pass through sieve opening Harvesting of Paddy Factors affecting combine performance Machine parameters: Crop parameters: โช Speed of reel and its position โช Crop moisture content & its โช Cutter bar speed & its adjustment condition โช Speed of threshing cylinder โช Time of harvest โช Speed of straw rack, sieve & โช Crop density blower โช Crop variety โช Machine vibration Operating parameters: Field parameters: โช Forward speed of combine โช Size & shape of field โช Height of cut โช Soil moisture content during โช Direct of cut w.r.t. plant orientation harvesting Harvesting of Paddy Sources of grain loss Header loss/Cutter bar loss: It is determined on those portions of ground, which are protected from combine afflux by the use of rolls of cloth. The loose grains and complete and incomplete ear heads fallen on the marked area, where pre-harvest losses were determined, shall be collected manually. Grain shattered by reel (speed, over matured crop, improper adjustment) Grain shattered by cutter bar (excessive vibration) Dropped before reaching the platform Missed by cutter bar due to improper registration or height adjustment Cylinder loss: Amount of unthreshed grain found from straw walker and cleaning sieve Harvesting of Paddy Sources of grain loss Rack and shoe loss: For determining the rack and shoe loss, the straw and chaff afflux is collected separately. To collect these, two rolls of cloth 30 m in length and one and half times the width of straw/chaff outlet is suspended on especially attached fittings beneath the rear of machine. As the sheets of cloth unroll, one sheet retains the afflux from straw walker and other from sieve for 20 m run length. Unrolling operation starts 5 m in advance and terminates 5 m ahead of end point. Pre-harvest loss: It is determined at minimum of three places randomly selected in the field where combine harvester is to be operated. The sample should be collected from the area having one-meter length in the direction of travel and full or half width of cutter bar of machine depending upon its size. All the loose grains, complete and incomplete ear heads fallen in the marked area have to be picked up manually without vibrating the plants before the machine is to be operated. This will give pre-harvest loss. Harvesting of Paddy Factors affecting grain loss Machine parameters: Crop parameters: โช Threshing cylinder speed โช Moisture content of crop โช Cylinder-concave clearance โช Lodging of crop โช Forward speed โช Variety of crop โช Reel index โช Crop density โช Reel position โช Height of cutter bar โช Blower speed โช Opening if cleaning sieve Tutorial A combine harvester having 4.20 m cutter bar is tested for harvesting crop and the following data was obtained i. Total area harvested = 100 mยฒ ii. Time taken = 20 sec iii. Free seed over rack = 150 g iv. Unthreshed over rack = 100 g v. Free seed over shoe = 500 g vi. Unthreshed over shoe = 150 g vii. Net grain collected in combine tank = 50 kg viii. Average cutter bar loss = 10.20 g/mยฒ Determine: (i) Total seed yield and total seed loss in kg/ha, respectively (ii) Various combine losses and total combine loss as percent of total seed yield (iii) Reel index, if peripheral speed of reel is 5.52 km/h Tutorial Solution: Total harvested area = 100 mยฒ (i) Total seed harvested = 0.15 + 0.1 + 0.5 + 0.15 + 50 + 1.02 = 51.92 kg Average cutter bar loss = 10.20 ร 100 = 1020 g x 1.02 kg Total seed yield per ha = 51.92/0.001 = 5192 kg Total grain loss = 51.92 - 50 = 1.92 kg Total grain loss per ha = 1.92/0.9 = 192 kg (ii) Various combine losses Cutter bar loss = (1.02/51.92) ร 100 = 1.96 % Rack loss: Threshed seed = (0.15/51.92) x 100 = 0.288 % Unthreshed seed = (0.1/51.92) x 100 = 0.192 % Shoe loss: Threshed seed = (0.5/51.92) ร 100 Unthreshed seed = (0.15/51.92) x 100 Total grain loss = 0.15 +0.1+0.5 +0.15 + 1.02 = 1.92 kg Hence, grain loss in respect of total seed yield per ha = (1.92/51.92) x 100= 3.6 % Tutorial Solution: Width of cutter bar = 4.20 m Total distance travelled = (100/4.2) = 23.8 m Total time taken to travel this length = 20 sec Hence, speed of operation would be = 23.8/20 = 1.19 m/s= 4.284 km/h Peripheral speed of the reel = 5.52 km/h Reel index = Peripheral speed of operation/Forward speed of operation=5.52/4.284 = 1.29 Design of Combine Harvester Design of header โ2 1 ๐ = 10 โ ๐ฃโ โ ฮต โ ๐โ โ ๐๐ โ 1 + ๐ฟ` Q = capacity of combine, kg/sec ๐ฃโ = harvesters working speed, m/sec ฮต = factor of use of cutting width, 0.9 - 0.951 ๐โ = header length, m ๐๐ = yield of grain q/ha ๐๐ ๐ฟ ` = straw factor = ๐๐ (straw to grain ratio varies 0.6-1.2 for wheat 1-2.5 for paddy) The proportion between header length (๐โ ), length of drum (๐๐ ) and the surface of concave (๐๐ ) for different sizes of combine are as follows: 1. For small combines (๐โ โค 2.1 m), ๐โ : ๐๐ : ๐๐ โค 1: 0.37: 0.8 2. For medium combines (2.1 m < ๐โ < 3 m), ๐โ : ๐๐ : ๐๐ โค 1: 0.36: 1 3. For large combines (๐โ โฅ3 m), ๐โ : ๐๐ : ๐๐ =1: 0.36 : (1.25-1.5) Design of Combine Harvester Design of crop conveyer ๐๐ = ๐ฟ๐ถ โ ๐๐ถ โ ฮต โ ๐ฃ๐ถ โ ฯ๐ โ ๐ ๐๐ = Conveyer output, kg/sec ๐ฟ๐ถ = Length of the inclined conveyer, m ๐๐ถ = Width of undershot conveyer, m ฮต = factor of filling ๐ฃ๐ถ = linear speed of conveyer, m/s ฯ๐ = bulk density of crop material in the conveyer belt, kg/m3 ๐ = % slip of material in the conveyer slit Refer book Agricultural machines, theory and construction Vol 2 By Kanafojski & Karwowski Design of Combine Harvester Capacity of horizontal feed auger ๐ 2 ๐ถ๐ = ๐ท0 โ ๐๐2 โ ๐ โ ๐ 4 ๐ถ๐ = Capacity of auger, mยณ/min ๐ท0 = Outside diameter of flight strip, m ๐๐ = Inside diameter of flight, m P = pitch of auger, m ๐= rotational speed of feed auger, m/s Assuming the auger fill factor = 2, capacity of feed conveyer (tons per hour) : fill factor x C (mยณ/min) x tons/mยณ x 60 Power to move material horizontally (๐โ ): ๐โ = (๐ถ๐ โ ๐ฟ โ F )/367 Power to lift material vertically (๐๐ฟ ): ๐๐ฟ = (๐ถ๐ โ ๐ฟ sinฮธ )/367 L = Length,m F= Multiplying power factor, if power is less than 1 kW it is equal to 1.5. If power lies between 1 & 2, take it as 1.25, If power lies between 2 and 4, take it as 1.1. If power lies between 4 and 5. take it as 1.0 Design of Combine Harvester Threshing Mechanism n= ๐๐๐๐๐โ๐๐๐๐ ๐ ๐๐๐๐ (๐ฃ) n= no. of revolution, rps ๐๐ท D = Dia of cylinder, m q= 0.25 โ ๐ ๐ โ๐โ๐๐ โ๐ q = feed rate of thresher ๐๐๐๐ ๐๐๐ 1+๐ฟแ ๐ ๐ = number of rasp-bars. แ ๐ (1 + ๐ฟ) ๐๐ = ๐ = revolutions of threshing drum /sec 0.25 โ ๐ ๐ โ ๐ โ ๐ ๐๐ = length of drum, m q = ๐๐ โ ๐ ๐ โ ๐๐ ๐ = 0.17 - 0.32 kg per metre ๐๐ = allowable feed rate of thresher, 0.35- ๐๐๐๐๐ ๐ก๐๐๐กโ ๐ ๐ฃ2 โ ๐ฃ1 ๐ฃ 0.4 kg/sec/m ๐= + ๐๐ฃ + ๐๐ฃ 3 1 โ ๐ถ๐ P= power required for operation of thresher, watt q=feed rate to combine, kg/sec ๐ฃ1 = initial velocity of plants, m/sec ๐ฃ2 = velocity of plant mass after impact, m/sec ๐ฃ = peripheral velocity of threshing drum, m/sec ๐๐๐๐ ๐๐๐๐ ๐ถ๐ = coefficient of friction between straw and thresher, 0.6 (assumed) m = constant = 0.85 -0.90 N per 100 kg weight of threshing drum, n = a constant = 0.065 N-secยฒ/mยฒ Velocity of plant mass after impact (v2) is given by, ๐ฃ2 = ๐ผ โ ๐ฃ , ๐ผ = 0.7-0.8 Design of Combine Harvester Cleaning Mechanism L% = permissible grain loss from straw walker, 0.4- Length of straw walker 0.5% of total grain. ๐๐ โ 100 โ ๐ โ๐๐ฟ๐ ๐๐ = feed rate to straw walker (kg/sec), 20% of feed ๐ฟ(%) = rate ๐ฟแ โ ๐ ๐ฟแ = straw factor q=amount of plant mass being fed to the combine Straw layer thickness (feed rate), kg/sec. แ ๐ (1โ๐ฟ) ฮผ = coefficient of separation, depends on straw layer h= thickness (h) on walker. ๐๐ โ๐ฃ๐๐ฃ โ๐๐ ๐ฟ๐ = length of straw walker, cm ๐๐ = width of straw walker, m Length of straw walker h = straw layer thickness, in m ๐ โ๐ ๐ ๐ฃ๐๐ฃ = average speed of straw grain mass over straw = walker, m/s ๐๐ โ ๐๐ = bulk density of straw layer on the walker, usually it is 12-17 kg/mยณ For h= 20 cm, ๐ =0.018/sec. So, m = 0.8 for heavy load, 1.2 for light load ๐๐ at any other layer thickness โ๐ can be determined Design of Combine Harvester Cleaning Mechanism Width of sieve (๐พ๐ ) ๐๐ = 0.9 โ 0.95 โ ๐๐๐ ๐๐๐ = width of straw walker ฦด ): 0.15-0.17 kg/sec/decimeter of sieve width Specific load of sieve (๐๐ ๐๐๐ฃ๐ Sieve area (๐จ๐๐๐๐๐ ) ๐ฦด ๐ด๐๐๐๐ฃ๐ = ๐๐ ๐๐๐ฃ๐ ฦด ๐ด๐๐๐๐ฃ๐ = area of sieve, in mยฒ ฦด = specific load of sieve (kg/sec/mยฒ) ๐๐ ๐๐๐ฃ๐ ๐ฦด = Q (1- ๐ฟแ C), in kg/sec/mยฒ Q = output of threshing unit ๐ฟแ = straw factor C = coefficient which depends on moisture content of grain. The value of coefficient, C for different range of moisture content Tutorial Q1. Determine the header length (Lh) of a 5.5 kg/s capacity self propelled combine harvester used in harvesting wheat crop (average yield 45.0 q/ha) at a speed of 5.4 km/hr. Assume that 90% of cutting width is utilized effectively during harvesting operation and straw factor for wheat crop as 1:1.5. Also design the threshing mechanism for the combine and power required to operate. Q2. Calculate the straw walker length for the combine harvester having a feed rate 5.5 kg/s in wheat crop. Assume permissible grain loss from straw walker as 0.3% of total grain output of combine and straw layer thickness on straw walker 15 cm. Also calculate the power requirement for threshing.