View Factor Orientation (or View factor or shape factor) plays an important role in radiation heat transfer. View factor is defined as, "fraction of radiation leaving surface 'i' and strike 'j' ". Summation Rule (View Factor) If there is are similar surfaces 'i' and 'j' , then: Blackbody Radiation Exchange Radiation Exchange between Opaque, Diffuse, Gray surfaces in an Enclosure 1. Opaque 2. Surfaces 3. Two surface enclosure Radiation Shield It is used to protect surfaces from radiation act like a reflective surface. References: Material from Class Lectures + Book named Fundamentals of Heat and Mass Transfer by Theodore L. Bergman + My knowledge. Photoshoped pics are developed. Some pics and GIF from Google. Videos from YouTube ( Engineering Sights ).
Several processing operations are done for the manufacturing gears, which are as:
Performing of Blank (with or without) ↠ important part of gears.
Annealing of Blank (Forged or Cast steel)
Machining of Gear Blank
Producing Teeth or Machining of Teeth
Finishing of Teeth (by shearing, grinding) ↠ if required
Full or Surface Hardening of Machined Gear ↠ case hardening
Inspection and Testing of Finished Gears
Manufacturing process involves following categories:
Forming ↠ shaping of plastic deformation in which volume remains constant (approx.) before and after the process. E.g.: Direct casting, rolling, powder metallurgy, injection molding, drawing, extrusion, stamping, forging, etc.
Machining ↠ shaping of parts by removing material (involves roughing, finishing operation). E.g.: Cutting, Shaping, Planning, Slotting, Broaching, Milling, Grinding, Hobbing, etc.
Forming Methods for Gear Manufacturing
Following are the methods for forming gears:
Sand Casting ↠ cast tooth are produced by melting and pouring into the mold cavity.
Die Casting ↠ casted tooth are produced by injecting material into mold cavity using high pressure.
Rolling ↠ deformation process in which thickness is reduced by compression forces exerted by two opposing rolls.
Powder Metallurgy ↠ pressing of metal powder in dies final shape.
Injection Molding ↠ producing teeth by injecting molten material into a mold.
Cold Drawing ↠ forming teeth from steel rods by drawing (pulling) them through hardened dies.
Extrusion ↠ shaping of teeth by pushing rod through a die having gear shape.
Stamping ↠ a cutting process in which sheet metal is placed between portions of die which removes the gear from the sheet.
Forging ↠ material shaping process by the application of localized compressive forces with power hammers, presses.
Machining Methods for Gear Manufacturing
Gears are manufactured in several routes:
Blanks are performed through machining, finishing and then teeth are produced.
Full Gears with teeth are made by different processes and then finished by further machining and grinding.
Accurate gears in finished form are directly produced by Near-Net-Shape process like rolling, plastic molding, powder metallurgy.
Machining methods for gear manufacturing are:
Forming (or Form-Cutting or Copying or Profiling Method) ↠ teeth profiles is obtained as the replica of the form of cutting tool (milling, shear cutting, teeth cutting).
Generation ↠ complicated tooth profile is provided by much simpler form cutting tool (edges) through rolling type, tool-work motion (Hobbing, gear shaping).
Solid Mechanics OR Mechanics of Materials OR Strength of Materials: It is the study of mechanics of body i.e. forces and their effects on deformable solids under different loading conditions. Deformable Body Mechanics: It is the study of non-rigid solid structures which deform under load. Deformation/Distortion ⇾ change of shape and size OR have some relative displacement or rotation of particles. It happens when we apply combined load. Rigid Body Motion ⇾ Translation or rotation of particles but having constant distance between particles. Since deformation occur at particular load. Below this load, every body is considered as rigid body . Types of Load: Point Load ⇾ Load apply on a single point i.e. concentrated load. Uniformly Distributed Load (UDL) ⇾ Load remains uniform throughout an area of element like beam. Varying Distributed Load (VDL) ⇾ Load varies with length with constant rate. Moment ⇾ It measures the tend...
Mechanical Injection System: Used to inject fuel into the combustion chamber. Fuel speed > air speed at delivery point to atomize fuel. Amount of fuel delivered into the air stream going into the engine is controlled by pump which forces the fuel under pressure. A device used to initiate and control the combustion process is called Mechanical Injection System. Functional Requirements of Injection System: Metering of Fuel: Used to control fuel to meet speed and load requirements of the engine. Injection Timing: Have proper injection timing to obtain max. power, fuel economy and proper burning. It is done by Camshaft or Push rod (Rocker Arm) Mechanism . Proper Control of Injection Rate: To get desired heat release pattern during combustion. Proper Atomization of Fuel: Proper making of droplets to make best Air/Fuel mixture. Proper Spray Pattern: Distribution of droplets to ensure rapid mixing of fuel & air. Uniform Distribut...
Flexible Mechanical Elements Flexible mechanical elements are defined as, " I nelastic elements to transmit power over large distances " . Purpose of using FME's is to simplify the design of a machine and reduce the cost . Used as replacement for gears, shafts, bearings, other rigid power-transmission devices. It can absorb shock loads and vibrations. Positive Drive ⇛ no slip between driver and driven component. Element Life ⇛ no infinite life and should be replaced at the first sign of deterioration (check wear, aging, loss of electricity). Performance of Different Transmission Types Belts or Belt Drives Belts are used where center distance between shafts is large. Pulley axes must be separated by a certain minimum distance (depend upon belt type and size) to operate properly. Because of belt flexibility and damping capability ⇛ reduce the transmission of unwanted shock and vibration between shafts. Power and torque capacities are limi...
Comments
Post a Comment
HI, we wI'll contact you later