The pulsating movement structure is the basic structural form commonly used in mechanical pencils, which is mainly composed of a pen barrel, a tip sleeve (pen tip), a fixed core protection tube (active damping), a clamp (flowering), a locking hoop, and a spring. 

When the core storage tube is acted on by the pressing pressure (finger pressure), it overcomes the elastic force of the spring and moves downward, and makes the jaws of the chuck open. It moves a certain length along the wall of the sheathing tube 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 the chuck to complete a pulsating core out process. 

In this way, the core can be continuously pulsated.

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