Skip to main content

HAMMER AND TYPES OF HAMMER USED IN BENCH WORK

 Hammers are used to strike a job or a tool. They are made of forged steel of  various sizes  ( weights ) and shapes to suit various purposes. A suitable range would be from 0.11 to 0.33 kg for light work such as clinching small rivets and dot punching, 0.45 kg of chiseling, 0.91 kg of heavier work such as chipping, the popular sizes of  bench work being 0.33 to 0.45 kg.

A Hammer consists of four parts namely peen, head, eye and face. The eye is normally made oval or elliptical in shape and it accommodates the handle or shaft. The end of the handle which fits into the eye is spread or split by forcing a metal wedge into to prevent the hammer head from flying of the handle during striking. The handle is made of elastic wood or bamboo and is so shaped and sized that when gripped it gives an easy feel to the hand. This "feel" is known as the "balance of the hammer. A well balanced hammer "feels" just right when the handle is grasped at the correct point. The face is hardened and polished well, and is slightly convex, instead of  flat to avoid spoilage of the surface of the metal to be hammered by the sharp edge of the flat surface. on an average , the handle should be 250 to 325 mm long. The length of the handles for light hammers is 200 to 260 mm. That for heavy hammers is 380 to 450 mm. 


Hammers


Hammers are classified , according to shape of the peen, as ball peen , cross peen, and straight peen hammers. 

Ball Peen Hammers : This is most common form of hammer and is sometimes called engineer's hammer or chipping hammer. The Peen has a shape of a ball which is hardened and polished. This is hammer is chiefly used for chipping and riveting. The size of the hammer varies from 0.11 to 0.91 kg. 


Ball peen hammer


Cross Peen Hammers : This is similar to ball peen hammer in shape and size except the peen which is across the shaft or eye. This is mainly used for bending, stretching, hammering into shoulders, inside curves, etc. The size varies from 0.22 to 0.91 kg.


cross peen hammer


Straight Peen Hammers : This hammer has a peen straight with the shaft, i.e, parallel to the axis of the shaft. This is used for stretching or peening the metal. The size varies from 0.11 to 0.91 kg.


Straight peen hammer


Soft Hammers : It is used where it is necessary to strike a metal a blow with the minimum damage to the surface, a soft-hammer , called mallet, is used. mallet heads go by the numbers or by the diameter of the head. They are made of raw hide, hard rubber, copper, brass, lead or most commonly - of wood. 


Soft hammer


Labels:

Comments

Post a Comment

Popular posts from this blog

ELECTRICAL COMPARATORS AND ITS WORKING

Electrical Comparators are used as a means of  detecting and amplifying small movements of a work contacting elements. An electrical comparator consists essentially of  a pick-up head or transducer for converting a displacement into a corresponding change in current and a meter or recorder connected in the circuit to indicate the electrical change, calibrated to show in terms of displacement. Generally, an amplifier is needed to provide the requisite sensitivity and to match the characteristics of different parts of  the circuit. Electrical comparators can be classified according to the electrical principle used in the pick-up head. Most of the comparators use either a differential transformer, an inductance bridge, a strain gauge or a capacitor as a means of detecting movement of the gauging element. There are different types of  electrical comparators. One kind called an electrolimit gauge is used to check or measure the outside diameter of a  roll. The object to be checked is place
Post a Comment
Read more

Advantages And Disadvantages Of Air Refrigeration System :

 Advantages Of  Air Refrigeration : 1. The refrigerant used namely air is cheap and easily available. 2. There is no danger of fire or toxic effects due to leakages. 3. The weight to ton of refrigeration ratio is less as compared to other systems. Disadvantages Of Air Refrigeration : 1. The quantity of  Refrigerant used per ton of refrigeration is high as compared to other systems. 2. The COP of the system is very low. Therefore running cost is high. 3. The danger of frosting at the expander valves is more as the air contains moisture content. 
Post a Comment
Read more

THROTTLE GOVERNING OF STEAM TURBINES

Steam Pressure at inlet to a steam turbine is reduced by throttling process to maintain the speed of the  turbine constant at part load and hence this method of governing is called "Throttle Governing".  Construction : Throttle governing system consists of  a centrifugal governor, a lever , an oil pump , a pilot piston , control valve , a relay piston and a throttle valve. The throttle valve is moved by a relay piston. The relay piston is actuated by pilot piston control valve. There are two piston valves covering ports in the pilot piston control valve without any overlap. These piston valves are operated by lubricating oil supplied by a gear pump at 2 to 4 bar. The oil returns to the drain from this chamber.  Working : When the turbine works on full rated load, the throttle valve will remain open. When the load is decreased, the energy output of the turbine becomes in excess and the turbine shaft speed increases. Hence, governor sleeve will lift. The upward movement of the
Post a Comment
Read more