IOSRD El-Bow power transmissionembed
Simple perpendicular power transmission element.
Available online at www.iosrd.org IOSRD International Journal of Engineering Volume 1, Issue 2, December 2014, Pages 71-77 Journal home page: http://iosrd.org/journals Design and development of EL-BOW power transmission Devchander V1*, Karthikeyan S2, Sathyavrath R3 and Surendhran K4 1, 2, 3, 4 Department of Mechanical Engineering, Vel Tech High Tech Dr.RR Dr.SR Engineering college, India *Corresponding author email address: firstname.lastname@example.org Abstract: This project “Design and development of El-bow power transmission” is simple and portable, hence skilful and has practical influence in transferring power at right angle without any gears. The El-bow Mechanism transfers the driving power towards the driven side in such a way that the angular forces produced in the holes are transferred with the help of el-bows which takes the driving power and the right angle drive is transferred towards the output slack and rod assembly. Hence a little friction occurs while the power is being transferred. Both hunting and back lash errors are absent. Therefore, an efficiency as high as 90-92% are possible in EL-BOW transmission mechanism. Nowadays world requires speed in each and every field, hence rapidness and quick working are very important. It is a working project and have guarantee of success. This project gives us knowledge, experience, and unique idea about manufacturing Keywords: Bent links, El-bow, Perpendicular power transmission. 1. Introduction It is a working project and can be manufactured in very short span of time. Hence we have selected this project. El-bow power transmission is an ingenious link mechanism of slider and kinematic chain principle . This mechanism is very helpful for transferring motion at right angles. However in certain industries it can also work at obtuse or acute angle plane and may be compared to worm and worm gear or bevel and pinion gear which are mostly used in the industry for various applications. The important feature of this mechanism is comparatively high efficiency between the driving and the driven power shafts with regards to gear efficiencies. 2. Literature survey The most commonly used type of gear profile is involute . They are used for cylindrical spur and helical gears as well as for conical gears like beveloid, hypoid and spiral bevel gears. Some properties of involute  (cylindrical) gears that had made them so unique are: Uniform transferring of rotational motion, independent of small error in Centre distance. The sum of the contact forces are constant and the direction of the total contact force always acts in the same direction. An involute gear can work together with mating gears with any number of teeth. Manufacturingis comparatively easy and the same tools can be used for machining gears with any numbers of teeth (Applies to hobs, shaper cutters, grinding worms, shaving cutters, but not to profile tools like milling cutters and profile grinding wheels). If the gears are perfectly rigid and no geometrical errors or modifications are present, the gears would transfer the rotational motion exactly, which means that a constant speed at the driving shaft would result in a constant speed at the driven shaft. The idea of nil friction leads to that, the gears would transfer the torque exactly. No force variations can exist and hence no vibrations and no sound (noise) will be generated. Of course, at present, there are geometrical errors, deflections and friction present, and accordingly, gears sometimes generate noise to such an extent that it becomes a quite problem. -Author: Mats Akerblom 3. Working This mechanism carries force through a el-bow. Transferring rotational motion around an axis generally involves gears, which is complicated, inflexible, clumsy-looking and ugly. This mechanism converts rotational motion using a set of cylindrical bars, bent to 90º, in a clever, simple and smooth way that transfers strong rotational force even in complicated position.The cylindrical housing has one degree of freedom i.e.,(rotation), the bent link has one degrees of freedom i.e.,(reciprocation). This condition is suitable for both driving and driven side. Initially when the drive is given at the input Copyrights© www.iosrd.org | All Rights Reserved 71 | Page IOSRD International Journal of Engineering (http://iosrd.org/journals) Volume 1, Issue 2, December 2014, Pages 71-77 side, the degrees of freedom of both cylindrical housing and bent links gets interconnected within one another and results in rotational motion at the driven side.The El-bow mechanism transfers motions at any fixed angle between the driving and driven shaft. This mechanism consists of number of pins that would be between 3 and 8, more the pins the smoother the operation is. Motion is transferred from input to the output shaft through the el-bow which is bent to the angles between the input to output shafts. These pins reciprocate inside hollow cylinders thus forming a sliding pair. Our mechanism has 3 such sliding pairs. Power is supplied by an electric motor. Motion is transferred from input to the output shafts through the bent links which are bent to conform to the angles between the driving and driven shafts. These bent links are located in the holes equally spaced in a circle and they are free to reciprocate in & out as the shafts revolve. This type of drive is generally suitable where quite operation at high speed is required. Even though this mechanism shows a perpendicular transmission, this drive can be applied also to shafts located at intermediate angle between 0* to 90*.In making this transmission, it is mandatory to have the holes for a given el-bow located precisely in the respective holes and must be equally spaced in radial and circumferential directions. If the holes are not drilled in the ends of the cylindrical housing i.e., “blind” or closed ends, there must be a small vent at the bottom of each hole for the escape of air compressed by the pumping action of the el-bow. These holes can use for lubrication purpose. Fig.1 Mechanism 4. Machine design Machine Design is an art of designing the structure of a machine. The resistive bodies with relatively constrained motions are known as machines. A machine is used to convert other forms of energies into mechanical energy (or) to transmit the energy. Modification of the existing design is to create new machines or structures and to improve the existing machines, to convert and control the motions. To design a simple component successfully, a better knowledge in applied sciences is vital. Primary knowledge about the strength, properties of material and metrology are essential. To determine the velocity, inertia force, and acceleration of the number of links in motion, knowledge in the theory of machines is important. The mechanics of machine are involved in the design. 5. Concept of the M.D.P. The following considerations are to be made in a machine design:a. The different types of stresses and loads created by the load. b. The kinematics of a machine (or) the motion of a part which depends on the type of motion, i.e. reciprocating, rotary, (or) oscillatory. c. In selection of a material, factors such as strength, resistance to corrosion, machinability, durability and weight of the material are to be considered d. Size and form of the parts. e. Resistance to friction an easy lubrication. Copyrights© www.iosrd.org | All Rights Reserved 72 | Page IOSRD International Journal of Engineering (http://iosrd.org/journals) Volume 1, Issue 2, December 2014, Pages 71-77 f. g. h. i. j. Operation economy. Using standardized parts. Manufacturing facilities which are available. Machine making cost. The number of products or machines to be manufactured. 6. Machine design-general procedure While designing the machine the following steps are generally adopted, a. A statement of problems specifying the purpose of the machine is prepared. b. For the desired motion, the relevant group of mechanism is selected. c. The force and energy on machine member is calculated. d. Suitable and appropriate materials are selected. e. The size of component drawing is determined. f. The component drawing is prepared and sent for manufacturing. g. Manufacturing and assembly of the machine. 7. Machine testing and testing for machine functioning 7.1. Shaft Design 7.1.1. Bending Material forces which are developed on any cross-sectional area of the shaft give rise to stresses in each and every point. The so called bending stresses are the result of the internal or resisting moment. 7.1.2. Torsion When the shaft is turned or twisted in such a way that both the shaft' axis and the axis of the couple coincide with each other. The shaft undergoes pure torsion and the resultant stresses at any point of the cross-section are either torsion stress or shear stress. 7.1.3. Combined Bending and Torsion In practice the shaft is subjected generally to the combination of bending and torsional stresses. The bending stresses are due to, a. b. c. d. Weight of the belt Pull of the belt Mounting eccentricity Misalignment Whereas the torsional movement might be due to, the direct or indirect twisting. Hence the shaft’s cross-section is simultaneously subjected to both the bending and torsional stresses. T= π/16 .τ.d3 Copyrights© www.iosrd.org | All Rights Reserved 73 | Page IOSRD International Journal of Engineering (http://iosrd.org/journals) Volume 1, Issue 2, December 2014, Pages 71-77 Power of motor = ¼ H.P = 746 x .25 = 186.5 N-m/s Speed of motor = 1440 rpm T = 1.23 N-m = 1230 N-mm Considering 25 % overload Tmax= 1238 x 1.25= 1525 N-mm Diameter =10.2mm Taking factor of safety = 2 Diameter(D) = 10 x 2 = 20mm 7.2. EL-bow Design Power of motor = ¼ H.P = 746 x .25 = 186.5 N-m/s Speed of motor = 1440 rpm T = 1.23 N-m = 1230 N-mm Considering 25 % overload Tmax= 1238 x 1.25= 1525 N-mm Diameter =10.2mm Taking factor of safety = 2 Diameter(D) = 10 x 2 = 20mm Table 1. Materials used Cylindrical Housing, Shaft Bright drawn steel High tensile strength EL-BOW Stainless steel Corrosion resistance, Wear resistance LINER Manganese, chromium alloy steel Corrosion resistance, Wear resistance RING Chromium or Nitrate coated steel High wear resistance Copyrights© www.iosrd.org | All Rights Reserved 74 | Page IOSRD International Journal of Engineering (http://iosrd.org/journals) Volume 1, Issue 2, December 2014, Pages 71-77 7.3. Static Load Analysis Fig.2EL-Bow Fig.3. Shaft 8. Efficiency improvement A sliding pair is formed between the rods and the cylinder transmits the main motion. The lapping and cleaning of pins have to be done and made capable of providing total interchangeability and similarly with the cylinder which are to be honed or lapped in order to achieve smooth finish of the surface. This will enable lesser frictional loss and also reduced heat generation. 9. Methods of cooling and lubrication All sliding members require lubrication to reduce friction and a cooling process to reduce frictional heat. The simplest technique to achieve the twin objectives is to drill oil holes in the body of the cylinder and fill them up with oil. But as the weight and use of the cylinders increase this technique may not be effective. 10. Modifications for enhanced performance Increasing the number of pins can enhance the efficiency and performance of the machine. We know from the working of the mechanism, the drawing pin is the innermost pin that pins the mechanism. By reducing the number required for the next pin to attain the innermost position, the performance of the mechanism as well as its life can be increased.To reduce the friction developed within the holes and to achieve Point contact the following design can be implemented. Copyrights© www.iosrd.org | All Rights Reserved 75 | Page IOSRD International Journal of Engineering (http://iosrd.org/journals) Volume 1, Issue 2, December 2014, Pages 71-77 10.1. Implementation of Liners Fig. 4. The main reason to implement liner is to reduce the wear in holes of cylindrical housing. 10.2. Implementation of rings Fig. 5. In order to reduce the area of contacting surface, rings can be used. This will reduce the friction. 10.3. Exploded View of Liner and Ring Assembly Fig. 6. Exploded View Of Liner And Ring Assembly 9. Applications a. This mechanism is used in gang drilling machine. b. It can be used in angular drilling machine. c. This mechanism can be used for a drive at clumsy location. d. It can be used in submarines for periscope movement. Copyrights© www.iosrd.org | All Rights Reserved 76 | Page IOSRD International Journal of Engineering (http://iosrd.org/journals) Volume 1, Issue 2, December 2014, Pages 71-77 Conclusion According to many engineering studies, the books on the subjects have elaborated that the gear drives have mechanical efficiency of very low level. Because of the factors relating under frictional forces between the mating gear teeth, the erratic hunting of the gears and the resultant backlash between the teeth is impossible to overcome and hence the efficiency will not exceed 55%. The recent gears of worm bevel type produced with Poly Propylene and Epoxy material, which eliminate the frictional forces comparatively, but used only very small applications due to less than 42% efficiency.This project is only a designed model. It has not been extensively researched or tested. But it is confidently felt that with improved manufacturing techniques and modifications, the efficiency can be enhanced to a considerable extent. References  Thomas Bevan, Theory of Machines (Pearson educational ltd, New Delhi, Third edition, 2011) 326.  Dr.R.Henry Xavier, Kinematics of Machines (S.Chand& Company ltd, First edition, 2008) 7-10.  V.B.Bhandari, Design of Machine elements (Tata McGraw Hill Education Private ltd, New Delhi, Third edition, 2012) 330-334.  SeropeKalpakjian, Steven R.Schmid, Manufacturing Engineering and Technology (Pearson educational ltd, New Delhi, Fourth edition, 2011) 625-639.  Dr.Kirpal Singh, Automobile Engineering (Standard Publishers Distributors, New Delhi, Vol II, 12th Edition, 2011) 146.  J.L. Meriam, L.G. Kraige, Dynamics (Wiley India (P.) ltd,Vol II, 2009) 323-326  KeennethG.Budinski, Michael K.Budinski, Engineering Materials Properties & Selection (PHI Learning pvt.ltd, New Delhi Ninth edition 2010) 365-460.  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