Project Report onSemi-automated paddy thresher

Submitted in partial fulfilment ofThe requirements for the degree of

Bachelor of Technology InInstrumentation and Control

ByKamya sati (111109031)Sujeet chandorkar(141209002)kailas dukale (141209004)

Under the Guidance ofProf. kalyani bhole

Department of Instrumentation and ControlCollege of Engineering Pune-411005(2014-15)Acceptance CertificateDepartment of Instrumentation and ControlCollege of Engineering Pune(An autonomous Institute of Government of Maharashtra)

The project entitled Semi-Automated Paddy Thresher submitted by Kamya Sati, Sujeet Chandorkar and Kailas Dukale having MIS No. 111109031, 141209002 and 141209004 accepted for being evaluated.

Prof. Mrs. Kalyani BholeDr.S.L.PatilProject GuideHeadDepartment of InstrumentationDepartment of Instrumentationand Controland ControlDate:-Date:-

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AbstractRice is one of the chief grains in India, and as such, is a major food crop, especially in the Eastern and Southern regions of India. Rice production accounts for a sizable amount of the economy. However, farmers that lack resources continue to harvest the same using traditional methods, which affects their yield, thereby affecting their earnings.We propose to build a semi-automated paddy thresher that will help farmers improve efficiency during threshing. It will also lower grain damage and reduce labor needed for threshing. We also hope to lower power consumption and provide a mechanism for speed control. We sincerely believe that the improved design can help enrich the lives of farmers across the nation. Table of ContentsAbstractList of Tablesiiii

List of Figuresiv

1: Introduction1.1: Methods of Threshing1.1.1: Flail1.1.2: Threshing Floor1.1.3: Pedal Operated Thresher 1.1.4: Threshing Machine/Combine Harvester1.2: Classification of threshers1.2.1: Feed-in type threshers1.2.2: Hold-on type threshers1.3: Proposed Paddy Thresher 1.3.1: Automated motor1.3.2: Vibrating mesh111112222223

2: Literature Survey2.1: Main components of Paddy Thresher2.1.1: Frame2.1.2: Threshing Drum2.1.3: Threshing teeth2.2: Optimization 2.2.1: Increasing Output Efficiency2.2.2: Portability and Ease of Use2.3: Power Source2.4: Safety and Cost 2.5: Summary of Literature Survey44444555556

3: Design3.1: Machine Dimensions3.2: Material Selection3.3: Process of Fabrication3.3.1: Building the Frame3.3.2: Fabricating the Threshing Drum3.3.3: Attaching the Motor3.3.4: Vibrating Mesh3.3.5: Fabricating the Hood3.4: Mechanism for Vibrating Mesh7778888889

4: Automation4.1: Single Phase Induction Motor4.1.1: Construction4.1.2: Working Principle4.1.3: Comparison between Single and Three phase Induction Motor4.1.4: Specification and Implentation4.2: Speed Control10101011111213

5: Conclusion and Scope for the Future5.1: Implemented Methods5.2: Future Scope5.2.1: Speed Control5.2.2: Fully automated Paddy Thresher5.3: Conclusion151516161616

6: References7: Acknowledgements 1820

iiiiList of Tables1: Optimal Specification2: Actual Dimensions of Paddy Thresher3: Specifications for Induction Motor6712

iiiList of Figures1: Pedal operated thresher1

2: Feed-in type thresher2

3: Slider-crank Mechanism4: Parts of Induction Motor910

5: Pulley system for Speed Reduction12

6: Block diagram for Speed Control13

7: AC voltage controller circuit8: Paddy Thresher [Full Body]9: Paddy Thresher [Threshing Drum]141516

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Chapter 1Introduction

There are many steps involved in the process of getting the rice from the fields and into our homes. First the rice stalks must be harvested from the fields. The next step of the process is threshing. It is the process of separation of the grain from the stalk. This can be done manually or by the action of a revolving mechanism. Grain damage is a potential problem faced during threshing.1.1 Methods of threshingSeveral methods of threshing exist. Some continue to be used today, while others have evolved with advancements in technology. A brief description of these methods is listed below.1.1.1 FlailIt is a hand held agricultural tool which is used to separate grain from the stalk. It is a labor intensive and time consuming process. The flail is used to beat grains on a threshing floor. The grains are later collected from the floor. 1.1.2 Threshing FloorThe stalks are spread across the threshing floor and animals like bulls or donkeys walk round and round dragging a threshing board to separate the grain from the stalk.1.1.3 Pedal operated paddy thresherThe idea was developed in Japan and is still popular with poor farmers in many parts of the world. It consists of loop type threshing drum with a supporting frame. It improves efficiency and is less labor intensive. However there are instances of injury to hands and arm while feeding the stalks into the thresher.Fig 1: Pedal operated thresher

1.1.4 Threshing Machine/Combine HarvestersIndustrialization helped remove much of the drudgery from the process of farm labor. The threshing machine uses the same principle as the above. Earlier they were hand-fed and horse powered but now they can be completely automated. Modern day combine harvesters use the same basic principles but are much larger in size.1.2 Classification of threshersThreshers can be broadly classified into two categories on the basis of method of feeding. Both categories come with their own set of advantages and disadvantages.1.2.1 Feed-in type threshersIn these types of threshers, the whole crop is directly fed into the machine. It provides higher throughput than hold-on type and allows the farmers freedom to move around. But these types of threshers are prone to clogging with the straw. It also has higher power requirement to drive the drum. Sometimes it also results in injuries to hands of the operator. 1.2.2 Hold-on type threshersFig 2: Feed-in typeIn these types of threshers only the panicle is fed into the machine. The straw remains intact and there is lower risk of injuries to the user. However it has lower throughput than feed-in type thresher.

1.3 Proposed Paddy ThresherEach of the above mentioned methods has its own set of advantages and disadvantages. The proposed paddy thresher is designed with the small farmer in mind. We hope to improve efficiency and yield while reducing labor. This can help small farmers improve their profit margins. It will also reduce the time spent in threshing which can be utilized elsewhere.1.3.1 Automated MotorNon automated threshers require a lot of manual labor which is time consuming and tiring. We propose to use an induction motor to automate the mechanism of the threshing drum. The farmer will have ON-OFF control with the help of a single switch.1.3.2 Vibrating MeshWinnowing is the process of separation of grain from the chaff. We propose to use a vibrating mesh to separate the paddy grains from the chaff after threshing. This can help reduce time spend in winnowing and requires no extra effort from the farmers side.

Chapter 2Literature Survey

There are numerous types of paddy threshers available in the market. Each design has some advantages and some disadvantages. We have identified the following focus areas for the literature survey: Main components of paddy thresher Optimization of components Power Source Safety and Cost2.1 Main components of paddy thresherThe thresher consists of three main components frame, threshing drum and threshing teeth

2.1.1 FrameThe body frame of the thresher should be made of a durable materials like cast iron or mild steel to increase life of the machine. The height of the frame should be comfortable for the user, so that he/she should not have to bend. The recommended height is around 105 cm.2.1.2 Threshing drumThe drum should be durable enough to take the load of the stalks. It should be constructed out of slats which are supported at each end by cylinder end discs. The length of the drum should not exceed 40 cm in case of single user.2.1.3 Threshing teeth The slats carry the threshing teeth. They should be arranged in linear manner with a distance of 4 cm. The height of the teeth should not exceed 6.5 cm. The shape of the teeth affects grain damage. To minimize damage to paddy grains, wire loop type teeth are preferred.

2.2 OptimizationOptimization is the methodology of selecting the best element with regard to some criteria. We wish to optimize the thresher for small farmers.

2.2.1 Increasing output efficiencyOutput efficiency of the thresher depends mainly upon the feed rate and the speed of the drum. The feed rate of the thresher must not be too high so as to prevent overloading the drum. The speed of the drum should not exceed 850 rpm so as to prevent grain damage.

2.2.2 Portability and Ease of UseFarmers prefer threshing machines which are portable as they can be used in any part of their field. The thresher should be easy to operate as most farmers are not well versed with the usage of highly technical machines.

2.3 Power SourcePedal powered threshers require a lot of human labor. To automate the threshing mechanism, one can use an electric motor or a diesel motor. Diesel motors, however, have very high carbon emission and pose a threat to the environment.Owing to the rising cost of diesel, electric motors are cheaper to run than diesel motors. Many farmers have subsidized electricity rates and single phase supplies. An induction motor requires a single phase supply and does not require much maintenance. An induction motor of 0.5 hp would be sufficient to power the drum.2.4 Safety and CostIn agricultural related injuries, accidents due to threshers are the second most common. Exposed rotating parts result in crushing or amputation of upper limbs. Hence, chute design is an important parameter to prevent injuries. The chute opening height should be at least 32 cm. Elbows should be kept away to prevent injuries.Targeting small farmers, the goal of the project is to offer a viably safe thresher at an affordable price. Also, the thresher should not require much maintenance.

2.5 Summary of Literature SurveyAccording to the literature survey, the following are the optimal specifications for a semi-automatic paddy thresher:ParameterDimensions

Frame Dimensions100 x 60 x 105 (in cm)

Drum Length35-40 cm

Plate Diameter27 cm

Tooth Spacing4 cm

Tooth Height6.5 cm

Power SourceSingle Phase Induction Motor

Speed of Drum600 - 800 rpm

Table 1: Optimal Specifications

Chapter 3Design

The optimal dimensions have been summarized in the literature survey (in Section 2.5). The design, however, involves more than a few technical specifications. In this chapter, we will cover the actual dimensions that were used to build our thresher as well as the materials that were selected for each component.3.1 Machine DimensionsThe machine was built according to the following dimensions:ParameterDimensions

Frame Dimensions90 x 60 x 75 (in cm)

Drum Length40 cm

Drum Diameter25 cm

Plate Diameter18 cm

Tooth Height6.5 cm

Tooth Spacing3.9 cm

Chute Opening35 cm

Table 2: Actual Dimensions of the Paddy Thresher3.2 Material SelectionAccording to Indian standards of paddy threshers, cast iron and mild steel are the recommended materials to build paddy threshers. For our project, we chose cast iron for many purposes, most important being its competitive price. Cast iron can therefore do the same job at a lower price. It is also easily available and has high tensile strength.The only problem with cast iron is that is more prone to corrosion as compared to mild steel, but this can be rectified with a paint job. For the base of the machine, we have used a 6 cm thick panel of wood so as to provide cushioning and stability to the machine.3.3 Process of FabricationThe process of fabrication follows the sub-points mentioned below in their exact order:3.3.1 Building the FrameThis is the first step in the process of fabrication. The frame was built using L-shaped bars made of cast iron. The dimensions used for the frame are as specified in Section 3.1.3.3.2 Fabricating the Threshing DrumThe drum was constructed using a series of slats, supported by a cylinder-end plate. Each slat is 0.5 cm thick and 5 cm wide. The distance between two neighboring slats is maintained at Z mm.The cylinder-end plates have a thickness of 0.2 cm and are used to support the slats. The threshing teeth are welded to the surface of the slat. We have selected Wire Loop type of teeth which have been welded at a distance of 4 cm to each other.3.3.3 Attaching the MotorWe have used a Flat Belt type pulley system to attach the motor to the shaft of the drum. This is the driving force of the machine. The pulley system also helps reduce the speed of the motor.3.3.4 Vibrating MeshThe vibrating mesh is used to separate the grain from the chaff. We have used a linkage assembly which converts the rotational motion of the drum into linear motion of the mesh.3.3.5 Fabricating the HoodThis is the final step in the process of fabrication. A metal sheet is bent and welded to the top of the thresher in order to prevent injury as well as preventing the grains from getting scattered.3.4 Mechanism for Vibrating MeshWe make use of the rotatory motion of the drum for the reciprocating motion of the mesh. A slider-crank can be used to convert circular motion into reciprocating motion.Link AB shown below in Fig is free to rotate 360 around the hinge while link BC oscillates back and forth because point C is hinged to a roller which restricts it to linear motion. Here the rotating link AB is the driver.

Fig 3: Slider-crank mechanism

Chapter 4Automation

Automation is the process of using control systems to operate equipment, reducing or removing human intervention. In this chapter, we will discuss the specifications of the induction motor used, followed by the method used for controlling the speed of the drum.4.1 Single Phase Induction MotorThe single phase induction motor is the heart of the paddy thresher machine. We have explained the construction and working of induction motor.4.1.1 Construction It has mainly two parts namely rotor and stator.Stator: As its name indicates stator is a stationary part of induction motor. A single phase ac supply is given to the stator of single phase induction motor.Rotor: The rotor is a rotating part of induction motor. The rotor is connected to the mechanical load through the shaft. The rotor in single phase induction motor is of squirrel cage rotor type.The construction of single phase induction motor is almost similar to the squirrel cage three phase motor except that in case of asynchronous motor the stator have two windings instead of one as compare to the single stator winding in three phase induction motor.Fig 4: Parts of Induction Motor

4.1.2 Working PrincipleWhen single phase ac supply is given to the stator winding of single phase induction motor, the alternating current starts flowing through the stator or main winding. This alternating current produces an alternating flux called main flux. This main flux also links with the rotor conductors and hence cut the rotor conductors. According to the Faradays law of electromagnetic induction, EMF gets induced in the rotor. As the rotor circuit is closed one so, the current starts flowing in the rotor. This current is called the rotor current. This rotor current produces its own flux called rotor flux. Since this flux is produced due to induction principle so, the motor working on this principle got its name as induction motor. Now there are two fluxes one is main flux and another is called rotor flux. These two fluxes produce the desired torque which is required by the motor to rotate.4.1.3 Comparison between Single phase and Three phase Induction Motor1.Single phase induction motors are simple in construction, reliable and economical for small power rating as compared to three phase induction motors.2.The electrical power factor of single phase induction motors is low as compared to three phase induction motors.3.For same size, the single phase induction motors develop about 50% of the output as that of three phase induction motors.4.The starting torque is also low for asynchronous motors.5.The efficiency of single phase induction motors is less as compare it to the three phase induction motors.4.1.4 Specification and ImplementationThe specifications of the induction motor used in our project are as follows:

ParameterValue

RotorSquirrel Cage Type

Output Power0.5 hp

Supply Voltage230 V, 50 Hz

Speed1440 rpm

Current5 A

Table 3: Specifications for Induction MotorThe speed of the motor (1440 rpm) is too high and would certainly have caused significant grain damage. We have used a pulley arrangement to bring down the speed of the induction motor. We placed a small pulley on the motor and a larger pulley on the shaft of the threshing drum. The size of the pulleys was calculated using the following formula:D1 P1 = D2 P2whereD1 = driving pulley diameterP1 = speed of driving pulleyD2 = driven pulley diameterP2 = speed of driven pulleyFig 5: Pulley System for Speed Reduction We require the speed of the drum to be 800 rpm. The plate diameter is 18 cm and the speed of the motor is 1440 rpm. Placing these values in the formula above, we get:d1 1440 = 18 800 d1 = 10 cm.To implement the above, we have used a Flat Belt pulley system.4.2 Speed ControlWe hope to control the speed of the single phase induction motor using triac and a 555 timer. The control circuitry used depends on one parameter voltage.Torque Developed in a Motor Square of VoltageWe control the voltage applied to the stator terminals of the induction motor using gate pulses from the triac. Delaying of the pulses to the gate reduced the voltage applied to the stator terminals of the induction motor, and as voltage and torque are proportional to each other, a decrease in torque simultaneously decreases the speed of the motor.The control circuit consists of the following: Triggering Circuit Triac Circuit Power Supply CircuitPower Supply Circuit provides a DC supply of 5 V and 12 V to devices requiring the biasing voltage. The triggering circuit is used to generate pulses which are then given to the triac as gate pulses. This acts as the trigger. The triac circuit acts as an intermediate between the induction motor and the supply.

Fig 6: Block Diagram for Speed ControlUsing thyristor, we can control stator voltage by using an AC voltage controller, where reverse parallel connected thyristors are used in phase between supply and motor. The stator voltage is reduced from its base value by increasing the firing angle of thyristor from 0 to 180.

Fig 7: AC Voltage Controller CircuitFor the speed control of single phase induction motor we are using method of stator voltage supply control. In this method of control we are using an intermediate part called AC cycloconverter between the AC supply and induction motor. Therefore supply voltage is controlled by controlling the gate pulses to the cycloconverter. And thereby torque is also controlled and thus the speed of the induction motor.

Chapter 5Conclusion and Scope for the Future

There is scope for improvement in the level of automation of the paddy thresher. Towards this, in conclusion, we will cover a summary of the methods weve used in our system and propose a scope for what can be done in the future.5.1 Implemented MethodsThe paddy thresher was built with the aim of helping small farmers increase their output, reducing labor required and providing a safe and standardized machine at an affordable cost. The machine is optimized to ensure easy use for the farmer and is built with safe guards to prevent accidents and injuries in a field with a high risk of amputation. Also, the machine can be used by a single farmer, as opposed to requiring multiple people operating a single machine.Another important aspect we considered was that our machine would test the tides of time and reduce the cost of maintenance. The machine also combines the process of threshing and winnowing, thereby reducing the work to be done by the farmer, as it has automatic grain separation.

Fig 8: Paddy Thresher [Full Body]

Fig 9: Paddy Thresher [Threshing Drum]5.2 Future ScopeWhile we have mentioned that our machine is a semi-automatic one, there is scope for increasing the level of automation in the thresher. A great way to do this is by implementing speed control of the threshing drum. We will discuss a few points below:5.2.1 Speed ControlThe speed of the threshing drum should be lowered while changing the bundle of stalks. As mentioned in Section 4.2, the speed of the threshing drum can be controlled using a triac and a 555 timer. This can help lower the power consumption as well as the risk of injuries, which will supplement the goal we had in mind while building this machine. We believe that the optimum speed we can reach using this method is 600 rpm.5.2.2 Fully Automatic Paddy ThresherThe current design of the paddy thresher requires the farmer to hold the bundle of stalks over the threshing drum. We propose to build a mechanism to hold these stalks in place and flip them over after a certain period of time using a simple flipping mechanism. A microcontroller can be used to trigger this flipping mechanism after a set period of time, which can be programmed in the microcontroller.5.3 ConclusionWhat we have built is a product that can be used in the field today. However, while we have identified the key areas that require change in a paddy thresher, we were unable to implement everything that we had hoped to. Nonetheless, what we have built is a step in the right direction, and a little bit of improvement can render it as a viable solution to an unaddressed problem faced by farmers for years.

Chapter 6References

1. Azouma, Ouezou Yaovi, Makennibe Porosi, and Koji Yamaguchi. "Design of throw-in type rice thresher for small scale farmers."Indian Journal of Science and Technology2.9 (2009): 10-14.2. Chimchana, D., V. M. Salokhe, and P. Soni. "Development of an Unequal Speed Co-axial Split-Rotor Thresher for Riceit."Agricultural Engineering International: CIGR Journal(2008).3. Singh, Gyanendra. "Agricultural Machinery Industry in India (Manufacturing, marketing and mechanization promotion)."Status of Farm Mechanization in India(2006).(2)4. Alizadeh, M. R., and M. Khodabakhshipour. "Effect of threshing drum speed and crop moisture content on the paddy grain damage in axial-flow thresher."Cercetari agronomice in Moldova (Romania)(2010).5. Kumar, Adarsh, et al. "Development of grain threshers based on ergonomic design criteria."Applied ergonomics33.5 (2002): 503-508.6. Singh, K. P., et al. "Optimisation of machine parameters of a pedal-operated paddy thresher using RSM."Biosystems engineering100.4 (2008): 591-600.7. Ukatu, A. C. "A modified threshing unit for soya beans."Biosystems engineering95.3 (2006): 371-377.8. Singh, Divya, and Deepa Vinay. "Optimization of machine parameters of Parvatiya Sugam motorized thresher using response surface methodology."Journal of Applied and Natural Science6.1 (2014): 207-213.9. Anon. 1982. IS: 3327: Specification for pedal operated paddy thresher. Bureau of Indian Standards, New Delhi.10. Kumar, A., Mohan, D., Patel, R., & Varghese, M. (2002). Development of grain threshers based on ergonomic design criteria. Applied ergonomics, 33(5), 503-508.11. Agrawal, Kamal Nayan, E. V. Thomas, and K. K. Satapathy. "Effect of thresher drive linkage design on human physiological workload of a pedal operated thresher." Agricultural Engineering International: CIGR Journal 15.1 (2012): 78-86.12. Alizadeh, M. R., and M. Khodabakhshipour. "Effect of threshing drum speed and crop moisture content on the paddy grain damage in axial-flow thresher."Cercetari agronomice in Moldova (Romania) (2010).13. Takahashi, Isao, and Youichi Ohmori. "High-performance direct torque control of an induction motor." Industry Applications, IEEE Transactions on 25.2 (1989): 257-264.14. Collins Jr, E. R., H. B. Puttgen, and I. I. Sayle. "Single-phase induction motor adjustable speed drive: Direct phase angle control of the auxiliary winding supply." Industry Applications Society Annual Meeting, 1988., Conference Record of the 1988 IEEE. IEEE, 1988.

AcknowledgementsWe would like to take this opportunity to express our deep sense of gratitude and respect to guide Prof. Mrs. Kalyani Bhole. It was our pleasure to have worked under her valuable guidance and constant encouragement which inspired us. We thank for the confidence she showed and developed in us.We are also thankful to Dr. S.L. Patil, Head of Instrumentation and Control engineering department and all faculty members who allowed all their facilities and extended their entire co-operation to us.Lastly we would like to thank Mr. Sanjay Deskhmuk , the owner of Laxmi Fabricators who has provided us with invaluable guidance in the process of fabrication.

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