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CHAPTER 1
INTRODUCTION
1.1 COMPANY PROFILE
The HMT machines tools Ltd, which is one of the world’s foremost machine tool manufacturing houses set up in Bangalore in the year 1952, in collaboration with M/S Oerikon machine tools Ltd, Switzerland from that time to this day, the nut has been producing products conforming to the latest international standard of quality and safety.
Though it was started in a small way in 1952, it has now the capacity to produce almost any type of component. The HMT Ltd, produces at present the following products.
 General purpose machines
 Special purpose machines
 Wrist watches
 Lamps
 Tractors
The HMT Ltd. has twelve factories all over India with eighteen divisions,
The Bangalore unit alone presents to the world market products such as:
 High production turret lathes
 Radial drilling machines
 Gear shapers
 Single and multi spindle automatic machines
 Grinding machines
 Numerically controlled machines
 Die casting machines
 Plastic injection moulding machines
 Grinding and milling machines
 Ball screw assemblies
The units of Bangalore division, manufacturing the above mentioned products according to nature , size and quality of the component. To do this various divisions have been made in HMT and they are:
 Small parts unit
 Heavy part unit
 Tool room
 Die casting unit
 Foundry unit
 Ball screw division
 Radial drilling machines
Well experienced technical personnel carry out the production of the various components in the above mentioned units. Apart from this, HMT is now in collaboration with at least thirty international companies so as to produce Indian technology in to the world market and thus save India a lot of foreign exchange. It would be very appropriate to mention, here that over 8000 HMT machines are in operation in over 70 countries across the world, following the supremacy of HMT products in and around India
1.2 GEARS
1.2.1 TYPES OF GEARS:
Gear is generic term for a mechanical contrivance, the function of which may be indicated by qualifying adjective. E.g-steering gears.
SPUR GEAR
It connects parallel shaft by teeth, parallel to axis and nominally constant from end to end. If accurately aligned, they produce no end thrust. If both wheel and pinion have external teeth they rotate in opposite directions. Sliding between the teeth occurs in transverse planes, i.e. in the planes perpendicular to the axis. The wheel may have internal teeth and is commonly called the annular pinion and rotate in same directions.
HELICAL GEARS
Helical gears not otherwise qualified, also connect parallel shaft. The tooth profile that is nominally constant from end to end. But teeth are of helical form and produce end thrust under load. For external gears the teeth of pinion and wheel are of opposite hand of helix and rotate in opposite direction.
Helical pinion may engage with the helical internal gear and both members then have teeth of same hand of helix and rotate in same direction. A helical rack has teeth, which are straight from end to end.
DOUBLE HELICAL GEARS
Each gear comprises two sets of helical teeth, of opposite hand so that their end thrust is in balance.
CROSSED HELICAL GEARS
The gears connect the skew shafts, both members may be helical gears or one may be a spur gear.
PARALLEL HELICAL GEARS
In these gears, the axes are parallel and the pitch is cylindrical. The tooth traces are helices and these helices may be left or right handed.
STRAIGHT BEVEL GEARS
In this type of gears, the axes are intersecting. The angle between the two axes, known as shaft angle is usually 90 degrees. The gear blank is a cone on which teeth are generated. These teeth are straight but the height of teeth gradually decreases and the sides of the teeth are tapered so that all lines when extended meet at a common point called the pitch cone apex.
1.2.2 APPLICATION OF GEARS
SPUR GEARS
 Turbine driving generator
 Motor driving generator
 Aircraft
 General purpose drives
 Rack & pinion
HELICAL GEARS
 Internal combustion engine driving compressor
 Large industrial gears
 Automotive transmission
 Gears of small commercial uses and gadgets
BEVEL GEARS
 Aircraft gear drives
 Automotive drive gears
 Marine gears
 Railway gears
 Tractors
WORM GEARS
 Agitators, electric motors
 Blowers, compressor
 Elevators