The first mechanical pencil in the world was invented in England in 1822. 19 15 years, the Japanese Takuji Hayakawa invented a kind of mechanical pencil. For export, he named this pencil "Universal Pointed Pencil". At first, this new writing tool was not recognized in Japan, and the demand in Japan increased rapidly. It was not recognized abroad until the export orders surged. Hayakawa also expanded its scale with its sales in mechanical pencil.
Mechanical pencil began to be popularized in Japanese campuses in the late1970s, and was mass-produced by Sharp Corporation of Japan. Before using mechanical pencil, you must put in a fine pencil lead made of graphite, and then close the back cover to prevent pencil lead from falling out. There is a spring in the mechanical pencil. Pressing the back cover can make the pen core extend from the front end for a fixed length and write fonts with the same thickness.
In order to keep writing smooth, wooden pencils need to be rolled frequently, and the appearance of mechanical pencil meets people's demand for convenient use. Mechanical pencil, as its name implies, is a pencil that can automatically or semi-automatically core without curling.
/kloc-In the middle of the 9th century, mechanical pencil appeared as a handicraft in Europe. /kloc-Germany began commercial production at the end of 0/9, but the lead core still needs to be polished by hand, and the output is limited. 1903, Japanese began to manufacture mechanical pencil by machinery, all of which were rotary. In the 1940s, American Parker Company produced the first batch of 0.9mm rotary mechanical pencil, and the lead core did not need to be sharpened manually. 1965, Japan successfully developed 0.5mm and 0.7mm synthetic resin thin lead cores, and developed a new three-jaw chuck to replace the traditional metal three-jaw chuck. In the same year, Japanese Pyrod fountain pen Co., Ltd. produced the pulsating fine core mechanical pencil for the first time. In 1970s, mechanical pencil with structural cores such as secondary push, double push and swing push were developed one after another. Faber 1979, Federal Republic of Germany? Universal Wheel Pencil Factory introduced mechanical pencil with automatic core removal for the first time. 1980 or so, the plastic two-jaw chuck was successfully developed, which made a new breakthrough in the material and structure of mechanical pencil.
classify
Mechanical pencil is divided into coarse core (above 0.9mm) and fine core (below 0.9mm) according to pencil lead diameter. According to the core jacking method, it can be divided into four types: falling core type, rotary type, pulsating type and automatic compensation type, and four types of movable pencils. Core-dropping type automatically discharges lead through the gravity of lead. Rotary conveying lead core. Pulse type (push type) conveys the lead core by pushing, and the structure has a push type, that is, pushing and discharging the lead core once. Two-push type, the pen mouth is pushed out of the pen holder for the first time and the lead core is pushed out for the second time. Double-head push type, adopting double-head structure, shortens the distance between the chuck and the nib, so that the last remaining 8 ~ 15 mm lead in the movable pencil can be ejected without pushing, and continuous writing can be carried out. Automatic compensation (automatic core jacking) can automatically compensate the lead core and write continuously without rotating or pulsating devices.
structure
Pulsating motion structure is a basic structural form commonly used in movable pencils, which is mainly composed of pen holder, tip sleeve (nib), fixed core protection tube (movable damping), chuck (flower), locking hoop, spring and so on. (See the structure diagram of pulsating mechanical pencil). When the core tube is under pressure (finger pressure), it moves downward against the elastic force of the spring, so that the clamping jaw opens. At the same time, the lead core leaves its original position in the core storage tube under its own gravity and moves along the wall of the core protection tube for a certain length under the control of the damping ring of the braking element. After the pressing pressure is released, the spring returns to its original position, and the lead core is automatically locked and positioned by the locking hoop and chuck, thus completing a pulsating core jacking process. According to this reciprocating motion, the core can be continuously pulsed.
Resin thin lead core
The lead core for mechanical pencil with fine core has the characteristics of high bending strength and good writing performance. Synthetic resin is mainly used as the binder of lead core, such as polyvinyl alcohol, asphalt, furan resin, polyvinyl chloride, ABC resin, vinyl chloride-vinyl acetate polymer and so on. Colorant with graphite as lead core; Commonly used solvents are water, ethanol, etc. Dioctyl phthalate and triphenyl phosphate are commonly used as plasticizers to reduce the flowing viscosity of resin at high temperature and improve the properties of molded products. Lead stearate is often used as a stabilizer to prevent resin aging and inhibit oxidation process; Liquid paraffin and low molecular weight polyethylene were used as lubricants to improve the fluidity of resin melt.
The manufacture of resin thin lead core is to form graphitized structure by high temperature roasting and carbonization under the protection of inert gas (such as argon) or under sealed conditions, so that it has high mechanical strength and good writing performance.