In the structural design of a Rollerball Pens, which parts play a key role in ensuring smooth writing and uniform ink flow?

The pen head is one of the most critical parts of a Rollerball Pens. It is in direct contact with the paper and determines the outflow of ink and the smoothness of writing. A ball made of metal or plastic extends from the front end of the Rollerball Pens. This ball rolls directly on the surface of the paper when writing. Its material must have high hardness, corrosion resistance and good lubricity to reduce friction with the paper and ensure smooth writing. The pen neck is the part that fixes the ball. It ensures that the ball will not fall off during writing and allows the ink to contact the ball through the pen neck, thereby achieving writing.
There is a longitudinal return air duct hole on the pen tongue, which allows air to enter the pen to balance the negative pressure generated when the ink flows out and ensure a continuous supply of ink. The outer side of the pen tongue is designed with a longitudinal infusion groove and an infusion slit connected to the return air duct hole. These structures ensure that the ink flows evenly from the ink storage device through the pen tongue to the ball, ensuring the continuity and stability of writing.
The ink reservoir is located inside the pen barrel and is responsible for storing ink and supplying it to the nib body. The water guide core is a slender tubular structure, the tail of which is inserted into the return air duct hole of the pen tongue. The function of the water guide core is to guide the ink from the ink reservoir to the pen tongue to ensure the continuous flow of ink. The core ink shell is a stepped tubular structure with a screen covering the front end. The core ink shell is inserted into the rear end of the connecting socket and fits tightly with the water guide core. The screen of the core ink shell plays the role of filtering the ink to prevent impurities in the ink from clogging the nib. The connecting socket is located at the front end of the pen barrel, and its shape matches the core ink shell. The middle part of the connecting socket is a three-section tube structure of a tapered tube, which helps the ink to flow out smoothly.
The ink transfer system of the Rollerball Pens consists of the nib body, the ink reservoir, and the connection between them. This system ensures the continuous and uniform flow of ink from the ink reservoir to the nib body. The tail of the water guide core is inserted into the return air duct hole to form a tight seal. When ink flows out of the ink reservoir, it flows along the water guide core to the pen tongue, and then flows evenly to the ball through the infusion groove and the suction infusion slit.
The core ink shell is inserted into the rear end of the connection socket and fits tightly with the water guide core. This design ensures a stable supply of ink and prevents ink leakage. When the ink flows out, negative pressure is generated in the pen. In order to balance this negative pressure, air enters the pen through the return air pipe hole. This air balance mechanism ensures a continuous and even outflow of ink.