ENGINEERING AND ARCHITECTURE FACULTY
DEPT. OF MECHANICAL ENGINEERING
by Can Uluç Birgüler and Halil Deniz Güler - Group: 4C
Mechanical Pencil
Description: A mechanical pencil contains a replaceable and mechanically extendable lead that wears away with use, designed to provide constant thickness without requiring sharpening.What are its functions?
A mechanical pencil is an implement for writing and drawing in which the solid marking core, which is usually graphite based, and called lead, does not lose its thickness.
When was it invented?
The first refillable and propelling pencil was patented by Sampson Mordan and John Isaac Hawkins in 1822. These two people are credited as the inventors of the mechanical pencil. Yet, the mechanical pencil is well known today throughout the world, thanks to Sharp's founder Tokuji Hayakawa. At his time, mechanical pencils were available but they were too fragile for everyday use, and aesthetically unappealing. By developing an original lead-thrusting device and inserting it into a metallic shaft, Hayakawa revolutionized one of the world's most convenient devices.
Where it is used?
Mechanical pencils are well suited to applications like general writing, technical drawing, and artistic purposes since mechanical pencils do not need to be sharpened. Most mechanical pencils can be divided into two basic classes by intended use. Technical mechanical pencils have a long (3-5 mm) thin cylindrical lead sleeve allows the lead to be run along a ruler edge, and, since precision and rigidity are very importent, the lead is frequently fixed permanently in position.
By whom it is used?
Although they are more expensive than regular pencils, mechanical pencils, are very popular amoungst students and everybody can use them. Yet, some countries prohibited mechanical pencils within the test rooms without any reason being given for such a ban.
How does it work?
The mechanism of most mechanical pencils is that when the push button is pressed, the spring is depressed and the 3-jawed chuck, chuck ring and lead begin to move downward in unison. As the lip of the chuck ring strikes the narrowing in the end cap it stops moving, releasing the chuck, which continues to travel for a short distance and pushes the lead forward.
