PRESENTORAftab ali khuhro

GEAR,S

CONTENTS• Introduction to Gears •Types of gears•manufacturing

INTRODUCTION TO GEARS• A toothed wheel that works with other to alter the relation b/w the speed of a driving mechanism to the speed of driven parts. • A gear is a component within atransmission device that transmitsrotational force to another gear or device

GEAR CLASSIFICATIONSGears may be classified according to the relative position of the axes of revolution. There are three axes. •parallel,

• intersecting,

•neither parallel nor intersecting.

PARALLEL GEARS • Two parallel and co-planar shafts are connected bythe gear as shown in figure these gears are known as parallel gears.• Teeth,s are parallel to the axis of rotation• The arrangement of these gears is also known as spur gearing arrangement because these gears have teeth parallel to the axis of wheel • Parallel gears are also known as helical gears because in which the teeth's are inclined to the axis

INTERSECTING GEAR When two bevel gears mesh, their imaginary vertices must occupy the same point. Their shaft axes also intersect at this point, forming an arbitrary non-straight angle between the shafts. The angle between the shafts can be anything except zero or 180 degrees. Bevel gears with equal numbers of teeth and shaft axes at 90 degrees are called intersecting gears.

NEITHER PARALLEL NOR INTERSECTING

• Those gears that have non-intersecting shafts these gears provide an effective answer for power transmission applications requiring high ratio speed reduction a limited space using non-intersecting shafts. neither parallel nor intersecting • These are ideal for applications requiring only limited load capacity

NEITHER PARALLEL NOR INTERSECTING

• Spiral bgenerators (like Gleason, Klingelnberg, Heidenreich & Harbeck, WMW Modul) manufacture bevel gears with an octoidal tooth profile. IMPORTANT: For 5-axis milled bevel gear sets it is important to choose the same calculation / layout like the conventional manufacturing method. Simplified calculated bevel gears on the basis of an equivalent cylindrical gear in normal section with an involute tooth form show a deviant tooth form with reduced tooth strength by 10-28% without offset and 45% with offset [Diss. Hünecke, TU Dresden]. Furthermore the "involute bevel gear sets" cause more noise

• evel gears can be manufactured as Gleason types (circular arc with non-constant tooth depth), Oerlikon and Curvex types (circular arc with constant tooth depth), Klingelnberg Cyclo-Palloid (Epicycloide with constant tooth depth) or Klingelnberg Palloid. Spiral bevel gears have the same advantages and disadvantages relative to their straight-cut cousins as helical gears do to spur gears. Straight bevel gears are generally used only at speeds below 5 m/s (1000 ft/min), or, for small gears, 1000 r.p.m.[13]

• Note: The cylindrical gear tooth profile corresponds to an involute, but the bevel gear tooth profile to an octoid. All traditional bevel gear

GEAR MANUFACTURING• Gear manufacturing refers to the making of gears. Gears can be manufactured by a variety of processes, including casting, forging, extrusion, powder metallurgy, and blanking. As a general rule, however, machining is applied to achieve the final dimensions, shape and surface finish in the gear. The initial operations that produce a semifinishing part ready for gear machining as referred to as blanking operations; the starting product in gear machining

GEAR GENERATION• In gear generating, the tooth flanks are obtained as an outline of

the subsequent positions of the cutter, which resembles in shape the mating gear in the gear pair. There are two machining processes employed shaping and milling. There are several modifications of these processes for different cutting tool used.

MANUFACTURING GEAR

Blended Powder Compacted Rigid Tooling ( Powder compacted rigidly) Pre-sinter

Repress or Coining Re-sinter Gear

GEAR SHIPING IN DISC CUTTER

GEAR SHAPING BY END MILL CUTTER

THE END MILL CUTTER SHAPE CONFIRMS THE GEAR TOOTH SHAPE. EACH TOOTH IS CUT AT TIME AND THEN INDEXED FOR NEXT TOOTH SPACE FOR CUTTING. A SET OF 10

CUTTERS WILL DO FOR 12 TO 120 TEETH GEARS. SUITED FOR SMALL VOLUME PRODUCTION OF LOW PRECISION GEARS.

TYPES OF GEARS1. According to the position of axes of the shafts.a. Parallel

1.Spur Gear2.Helical Gear3.Rack and Pinion

b. IntersectingBevel Gear

c. Non-intersecting and Non-parallelworm and worm gears

SPUR GEAR• Teeth is parallel to axis of rotation

• Transmit power from one shaft to another parallel shaft

•Used in Electric screwdriver, washing machine and clothes dryer• External and internal spur gear