# Universal Joint - DME

Student at VIT UNIVERSITY
2 Jun 2017
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### Universal Joint - DME

• 1. REPORT ON DESIGN AND ANALYSIS OF UNIVERSAL JOINT SUBMITTED BY: Ankit Sahu (14BMA0042) Utkarsh Anand (14BME0688) Vivek Patodkar (14BME0326) SUBMITTED TO: Venkatesan S.
• 2. INDEX S.NO CONTENT 1. ABSTRACT 2. PROBLEM STATEMENT 3. NOMENCLATURE 4. INTRODUCTION 5. OBJECTIVES 6. COUPLING 7. NUMERICAL 8. MACHINING PROCESS 9. METHODOLOGY 10. DISCUSSION & CONCLUSION 11. REFERENCES
• 3. 1 ABSTRACT A coupling is a device used to connect two shafts together at their ends for the purpose of transmitting power. The primary purpose of couplings is to join two pieces of rotating equipment while permitting some degree of misalignment or end movement or both. A Universal coupling is a special type of coupling in which misalignment of shafts is allowed. Shafts are free to move any direction in order to transmit torque or power from one shaft to another. In this project work a Universal coupling was designed, in which safe torque on shafts and pin size of cross determined. Finally, the Universal coupling made by Mild Steel, which is low cost and available in every workshop.
• 4. 2 PROBLEM STATEMENT Yoke assemblies are one of the most important components in steering system of an automobile.it generally subjected to torsional stresses and bending stresses due to weigh of the components. The stresses in either direction, while moving the vehicle to the right or to the left, happen to be a source of failure of the mechanical joint. The two halves of the yoke, the web connecting the two halves or the shaft in the linkages are prone to failure. In such event, the driver could lose control leading to an accident. The steering yoke being a component posing threat to the ‘safety’ of the vehicle and its occupants, the design of the same needs to be reviewed for encoring structural integrity. The design review could look into aspects dealing with the material properties and/or the geometry of the part/s. For this work no radical change is sought in design and the existing design shall be reviewed for feasible alternatives calling for minimal changes in the development or production further.
• 5. 3 NOMENCLATURE Symbol Description Ns2 …………………………………………………. Angular velocity of the driven shaft Ns1 ………………………………………………… Angular velocity of the driver shaft Θ……………………………………………………. Angle between axes of the shafts α………………………………………………….... Angle of the driving shaft from the position where the pins of the drive shaft yoke are F……………………………………………………. Force M……………………………………………………Torque applied to shaft Sb………………………...…………………………. Bearing stress Ss…………………………………………………. Transverse shear stress Sc……………………………………………….…. Compressive stress A…………………………………………………...Cross-sectional area of pin d………………………………………………...…Diameter of pin I……………………………………….……….…. Mass moment of inertia
• 6. 4 Introduction: Couplings are mechanical elements that ‘couples’ two drive elements which enables motion to be transferred from one element to another. The drive elements are normally shafts. We tend to see lot of applications of the couplings mainly in the automobiles, for example the drive shaft which connects the engine and the rear axle in a bus or any automobile is connected by means of a universal joint. The primary purpose of couplings is to join two pieces of rotating equipment while permitting some degree of misalignment or end movement or both. By careful selection, installation and maintenance of couplings, substantial savings can be made in reduced maintenance costs and downtime. There are various types of coupling based on area of application and misalignment or degree of freedom to move in any direction. Such as the universal coupling allows the shafts to move in any directions. The different types of alignments are: Fig.1.1: Different types of alignment Details about different types of coupling will be discussed latter.
• 7. 5 OBJECTIVES: The main objectives of this project work are- I. To solve a problem related to Universal coupling II. To design that problem III. To calculate the safe torque on shaft. IV. To know about its application.
• 8. 6 COUPLING Historical Background: The main concept of the universal joint is based on the design of gimbals, which have been in use since antiquity. The first person known to have suggested its use for transmitting motive power was Gerolamo Cardano, an Italian mathematician, in 1545, although it is unclear whether he produced a working model. In Europe, the device is often called the Cardan joint or Cardan shaft. Christopher Polhem of Sweden later reinvented it, giving rise to the name Polhemsknut in Swedish. Gaspar Schott ((1664), who called it the paradoxum, but mistakenly claimed that it was a constant-velocity joint. Shortly afterwards, between 1667 and 1675, Robert Hooke analysed the joint and found that its speed of rotation was nonuniform, but that this property could be used to track the motion of the shadow on the face of a sundial. The first recorded use of the term universal joint for this device was by Hooke in 1676, in his book Helioscopes. He published a description in 1678, resulting in the use of the term Hooke's joint in the English-speaking world. In 1683, Hooke proposed a solution to the non-uniform rotary speed of the universal joint: a pair of Hooke's joints 90° out of phase at either end of an intermediate shaft, an arrangement that is now known as a type of constant-velocity joint. The term universal joint was used in the 18th century and was in common use in the 19th century. 19th century uses of universal joints spanned a wide range of applications. Numerous universal joints were used to link the control shafts of the Northumberland telescope at Cambridge University in 1843. The term Cardan joint appears to be a latecomer to the English language. Coupling: Couplings are mechanical elements that ‘couples’ two drive elements which enables motion to be transferred from one element to another. The drive elements are normally shafts. Couplings are used to connect two shafts for torque transmission in varied applications. It may be to connect two units such as a motor and a generator or it may be to form a long line shaft by connecting shafts of standard lengths say 6-8m by couplings.
• 9. 7 Types of Coupling: Based on the area of applications there are various types of coupling available. But they are generally categorized in the following varieties- i. Rigid Couplings ii. Flexible or Compensating Couplings iii. Miscellaneous Couplings Rigid Couplings: Rigid Couplings are mainly used in areas where the two shafts are coaxial to each other. There are many types of couplings that fall under the rigid couplings category. They are i. Flanged Coupling ii. Muff coupling Fig : Flanged Coupling Fig : Muff coupling
• 10. 8 Flexible or Compensating Couplings : Flexible couplings are normally used in areas where the coaxiallity between the connecting shafts is not always assured and in areas where there is a possibility of occurrence of shocks in the transmission is applicable. They are also called as Elastic Couplings. By construction these couplings tend to have an elastic member in between the two connecting entities. The different types of flexible couplings are  Flanged Pin Bush Couplings  Bibbly Coupling  Gear Tooth Coupling  Tyre couplings  Elastomeric Couplings  Oldhams Coupling  Universal Coupling or Hooke’s Coupling (OUR CONCERN)
• 11. 9 Miscellaneous Couplings: This group of couplings incorporate design features which are frequently unique, approximations or combinations of universal, Oldham and flexible shaft couplings. Such as- Jaw type coupling and Sleeve type coupling. Universal Coupling or Hooke’s coupling: A universal joint, (universal coupling, U-joint, Cardan joint, Hardy-Spicer joint, or Hooke's joint) is a joint or coupling that allows the shafts to 'bend' in any direction, and is commonly used in shafts that transmit rotary motion. It consists of a pair of hinges located close together, oriented at 90° to each other, connected by a cross shaft. The universal joint is not a constant velocity joint.
• 12. 10 Fig : Universal Coupling A simple brief about Universal Coupling: A universal joint is like a ball and socket joint that constrains an extra degree of rotational freedom. Given axis 1 on body 1, and axis 2 on body 2 that is perpendicular to axis 1, it keeps them perpendicular. In other words, rotation of the two bodies about the direction perpendicular to the two axes will be equal. In the picture, the two bodies are joined together by a cross. Axis 1 is attached to body 1, and axis 2 is attached to body 2. The cross keeps these axes at 90 degrees, so if you grab body 1 and twist it, body 2 will twist as well. A Universal joint is equivalent to a hinge-2 joint where the hinge-2's axes are perpendicular to each other, and with a perfectly rigid connection in place of the suspension. Universal joints show up in cars, where the engine causes a shaft, the drive shaft, to rotate along its own axis. At some point you'd like to change the direction of the shaft. The problem is, if you just bend the shaft, then the part after the bend won't rotate about its own axis. So if you cut it at the bend location and insert a universal joint, you can use the constraint to force the second shaft to rotate about the same angle as the first shaft.
• 13. 11 Fig 2.10: A simple brief about U joint Types of Universal coupling: The universal couplings are categorized as- i. Single joints ii. Double joints iii.Telescopic or assembled joints Single joints Universal coupling: Precision single joints suit angles up to 45° and speeds to 4000 r/min. Shaft sizes 6 to 50 mm, dimensions to DIN 808. Fig : Single Joint Fig : Double joint
• 14. 12 Double joints Universal coupling: Precision double joints suit angles up to 90° and give constant velocity output. Shaft sizes 6 to 50 mm, dimensions to DIN 808. Assembled joints Universal coupling: Telescopic universal joint with plain bearings either to standard lengths or customised to your requirements. Angles up to 45° per joint and speeds to 1000 r/min, Type HA offers higher speeds. Fig 2.13: Telescopic Joint Field of Applications of Universal Coupling: Typical applications of universal joints include-  AUTOMOBILE  Aircraft  Appliances  Control mechanisms  Electronics instruments  Medical & optical devices  Ordinance radio  Sewing machines  Textile machineries etc.
• 15. 13 Material: Considering cost, strength, ease of access taken into account the selected material for this design is MILD STEEL. Machine & Apparatus Required:  Lathe  Drilling  Grinding machine  Welding apparatus Selection Guide:
• 16. 14 Machining Processes: Drafting: It’s a pre-manufacturing process in which a replica of the designed prototype is made. Fig.4.1: A typical draft Fig 4.2: Gas Cutting Gas Cutting: Oxy-fuel welding (commonly called oxyacetylene welding, oxy welding, or gas welding in the U.S.) and oxy-fuel cutting are processes that use fuel gases and oxygen to weld and cut metals, respectively. The common methods used in cutting metal are oxygas flame cutting, air carbon-arc cutting, and plasma-arc cutting. The method used depends on the type of metal to be cut and the availability of equipment. As a Steelworker, oxygas or air carbon-arc equipment is the most common type of equipment available for your use. Facing:Facing is the process of removing metal from the end of a work-piece to produce a flat surface. Most often, the workpiece is cylindrical, but using a 4-jaw chuck you can face rectangular or odd-shaped work to form cubes and other non-cylindrical shapes.
• 17. 15 facing operation on Lathe machine Turning operation on Lathe machine Turning:Turning is the removal of metal from the outer diameter of a rotating cylindrical work-piece. Turning is used to reduce the diameter of the workpiece, usually to a specified dimension, and to produce a smooth finish on the metal. Often the workpiece will be turned so that adjacent sections have different diameters. Grinding:Grinding is a finishing process used to improve surface finish, abrade hard materials, and tighten the tolerance on flat and cylindrical surfaces by removing a small amount of material. Information in this section is organized according to the subcategory links in the menu bar to the left. Fig.:Grinding operation Fig :Drilling operation Drilling:Drilling is a cutting process that uses a drill bit to cut or enlarge a hole of circular cross-section in solid materials. The drill bit is a rotary cutting tool, often multipoint. The bit is pressed against the work piece and rotated at rates from hundreds to thousands of revolutions per minute. This forces the cutting edge against the work-piece, cutting off chips from the hole as it is drilled.
• 18. 16 Methodology: Various Machines were used for several machining processes: - I. Lathe machine was used for facing, turning. II. Drilling machine was used for drilling & boring. III. Grinding machine was used for surface finishing. IV. Welding apparatus was used to connect different parts at the time of setting up.
• 19. 17 NUMERICAL Introduction: To design is either to formulate a plan for the satisfaction of a specified need or to solve a problem. If the plan results in the creation of something having a physical reality, then the product must be functional, safe, reliable, competitive, usable, manufacturable, and marketable. Design is an innovative and highly iterative process. It is also a decision-making process. Decisions sometimes have to be made with too little information, occasion-ally with just the right amount of information, or with an excess of partially contradictory information. Decisions are sometimes made tentatively, with the right reserved to adjust as more becomes known. The point is that the engineering designer has to be personally comfortable with a decision-making, problem-solving role. Problem A universal coupling (universal joint, or Hooke’s joint) is used to connect two shafts which intersect but which are not necessarily in the same straight line, as shown in Fig below. The angular velocity of the output shaft is not equal to the angular velocity of the input shaft, unless the input and output shafts are in line. The ratio of speeds is given by Where Ns2 = angular velocity of the driven shaft Ns1 = angular velocity of the driver shaft θ=angle between axes of the shafts α= angle of the driving shaft from the position where the pins of the drive shaft yoke are in the plane of the two shafts. A torque of 40N m is applied to shaft S1 of a universal joint in which S1 and the output shaft S2 are in the same horizontal plane.
• 20. 18 Problem fig a. Determine the torque on shaft S2 for the position shown in Fig. b. Determine the size of the pins of the connecting cross for an allowable bearing stress of 14 MPa (per projected area), an allowable bending stress of 140 MPa, and an allowable shear stress of 70 MPa. c. Calculate the maximum shear stress on section E-E, which is 50 m from axis Y-Y.
• 21. 19 Solution: (a) The components of F, acting on the shaft S1, are F cos200 and F sin200 . The torque acting on the shaft S1 due to the action of the cross is Mt= ( F cos200 )(0.05) or, 40 = ( F cos200 )(0.05) or, F = 851N The torque on the shaft S2 is 0.05 =(851)(0.05) = 42.6 Nm. (Ans.) Solution fig
• 22. 20 (b) (1) The size of the pins will depend on the maximum load, which occurs for the position shown. The maximum pin load is 851N. Diameter of pin based on bearing: Sb = F/A or, 140 * 106 = 851/(0.006d) . or, d = 10 mm (2) Diameter of pin bending on based: s = M c /I or, or, d = 7.2 mm (3) Diameter of pin based on transverse shear: or, or, d = 4.6 mm Therefore, bearing dictates the minimum size of pin; a 10mm diameter pin should be satisfactory.
• 23. 21 (c)Maximum compressive stress at section E-E is Maximum shear = (½)* (65.9) = 33 Mpa (Ans.) Our Designed dimension: Dimension of the cross
• 24. 22 CAD design and Rendered view: Fig 3.4: Dimensions of the shaft Fig : Cad design of universal coupling
• 25. 23 Rendered view of the cad design
• 26. 24 ANSYS ANALYSIS CROSS  Geometry  Meshing  Factor of safety  Deformation  Stress
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• 31. 29 TORQUE
• 32. 30 STRESS