Write an expository essay on Mechanical Pencil

Mechanical pencils are used for writing.

Like a ballpoint pen, the automatic pencil can continue to write without pressing, and the refill automatically produces lead, so that the refill can withstand the writing pressure, is not easy to break, and reduces waste.

The automatic pencil with continuous lead core is a writing instrument that ensures the continuous output of the lead core to compensate for the wear of the lead core during the writing process. Its principle is to use the intermittent pressure when writing, press the lead core sleeve to move backwards, and use the return force of the spring and the clamping force of the damping ring to pull out the lead core. As long as you push the head a few times, a plurality of lead cores in the lead core tube can be sent to the lead core sleeve to replace the used lead core after passing through the core tube, the core tube, the clip and the damping ring, so as to achieve the purpose of continuously transporting multiple lead cores.

The utility model is suitable for various specifications, the lead core and colored pencil of various hardness, and the advantage is that the operation is simple in use, and it is convenient to use.

The principle of this paragraph: unscrew the head of the pencil, you will see a two-petal plastic sheet covered with a metal ring, when you don't act, this metal ring covers the two petals of plastic sheet, and uses friction to bite the lead core, when you move, this part (the plastic sheet in the metal ring) goes down together, and when it reaches a certain position, the metal ring is resisted to stop falling, and the plastic sheet continues to fall, because they are separated, and the shape is separated outward at a certain angle, in the natural state they can't bite the lead core, So when they are free from the constraints of the metal ring, the lead core is not constrained and descends, but only a distance, but your action triggers quickly the pencil rebounds, and the metal ring covers the plastic sheet, which is the principle, let the lead core drop a short section in a short time.

Mechanical pencils use the principle of discarding and repairing.

The same principle is also firecrackers; catalysts in chemical reactions; The grinding wheel remains sharp as the sand falls off; When the cutter head is not sharp, you can remove the cutter head and re-sharpen the utility knife.

The principle of discarding and repairing is described as follows: the parts of an object are discarded (discarded, dissolved, volatilized, etc.) after they have fulfilled their function or become useless, or have been altered in the course of work; Parts of the object that have been used should be restored during the work.

How mechanical pencils are designed:

The pulsating movement structure is the basic structural form commonly used in the movable pencil, which is mainly composed of a pen barrel, a pointed sleeve, a core tube, a clamp, a locking hoop, a spring, etc.

When the core storage tube is subjected to the action of the pinch pressure (finger pressure), it overcomes the elastic force of the spring and moves downward, and makes the clamp head claw piece open, and at the same time, the lead core relies on its own gravity to leave the original position in the core storage tube, and moves along the core guard pipe wall for a certain length under the control of the damping ring of the braking element.

After the pressure is released, the spring returns to its original position, and the lead core is automatically locked and positioned by the locking hoop and the clamp head to complete a pulsating core process. Reciprocating in turn can continuously pulsate the core.

I have a pencil, a pen, and an eraser in my stationery box. Today, not only how, I hear"Brush lala, brush lala"The sound of quarrels. It turned out that the pencil and the pen were arguing.

Pencil laughed at the pen and said:"You useless thing, the little master made a mistake, you can't even wipe it off, you can only paint a black bump. Not only is it ugly, but it's also a waste of paper! Look at me, the writing looks so good, it's clear and colorful, and you can use an eraser to make mistakes! "

The pen also said sarcastically with a contemptuous tone"Disgusting, you won't be any better a**. In modern society, you have been eliminated, if it weren't for my fountain pen, you might as well be a bunch of garbage, don't be sentimental!

The pencil argued again:"Hmph, why are you so angry? Drawing and so on are inseparable from our pencil family. "

The pen shouted again"Although I can't erase my writing mistakes, the words I write are clear and beautiful, and they are not as black and unclear as you. "

Then, they scolded one on the left and one on the right, and quarreled fiercely. The two of them looked for an eraser review. Eraser said:"The two of you only see your strengths, not your weaknesses. It is not right to mock others because they are better than others. "

Write the origin, appearance, and function of the mechanical pencil, and write it like this.

Hello, mechanical pencil began to be popularized in Japanese schools in the late 1970s, and was mass-produced by the Japanese Sharp company, mechanical pencil needs to be put in a thin refill made of graphite (commonly known as lead core) before use, and after putting in the refill, close the back cover to prevent the refill from falling out. The mechanical pencil has a spring inside, and pressing the back of the lid allows the refill to extend from the fixed length of the front and write the same thickness.