A brief analysis of the structure, classification, installation and precautions of scrapers in the NiMH No.7 batteries coating process

1. The structure of the scraper

The back of the knife is also usually called a gasket. The function of the back of the knife is:

Ensure that the blade is in good contact with the layout and has appropriate pressure to increase the elasticity and stiffness of the scraper blade.

2. Classification of scrapers

The extension length of the scraper is different, and the blade bends to different degrees when scraping, forming a hard scraper and a soft scraper.

Comparison of the advantages and disadvantages of hard scrapers and soft scrapers:

3. Installation of scraper

(1) Installation basis

The graphics, text and other information reflected in the printing sample.

Plate roller type:

Line version, layered version, transitional version

(2) Installation steps

①The length of the scraper should be 10mm~20mm longer than both ends of the printing plate to avoid ink splashing at both ends of the printing plate.

② The blade back and blade groove must be cleaned to prevent the ink block from affecting the flatness of the scraper installation.

③Place the scraper under the support gasket and install it into the knife slot. Generally speaking, the back of the blade protrudes from the blade holder by 15mm to 25mm. The scraper blade extends 5mm to 8mm more than the back of the blade.

④ Ensure that the scraper blade and blade back are level and straight, and the extended length is the same on both sides.

⑤The softness and hardness are moderate. Press the fixing screws sequentially from the middle to both sides. There should be no wavy shape. Polish it with sandpaper and clean it. If there are wavy parts, they need to be reinstalled.

(3) Installation location:

Remarks: ○ is the imprinting point between the printing plate cylinder and the pressure roller; A is the contact point between the squeegee and the printing plate.

analyze:

Volatile ink is used in gravure printing. The shorter the arc length A○ between the contact point A between the squeegee and the printing plate and the imprinting point ○, the smaller the change in ink viscosity will be, and the better it will be for ink transfer.

Example:

The new image roll single package in production, many colleagues say that the transfer cannot be done, and the plate is blocked. Most of the time, this point is ignored (layered version), that is, the arc A○ distance is too long, the shallow net is superimposed, and the ink is scraped by the scraper. Finally, the ink has not been transferred to the substrate, and the solvent in the ink evaporates too quickly, resulting in poor transfer or dry plate (this is what colleagues usually call "pushing the knife forward a little").

Generally speaking:

The distance between the contact point of the squeegee and the printing plate and the pressing point of the pressure roller is 1/4 of the diameter of the plate roller.

(4) Installation angle:

Definition of scraper angle:

The angle α formed by the scraper and the tangent line L passing through the contact point A between the scraper and the plate roller. The scraper angle is generally 30 degrees to 60 degrees, and the acute angle α is generally <90 degrees.

analyze:

Because the included angle α is too large, the distance between the contact point B and the imprinting point ○ is large, which causes the time from scraping to printing to be too long, which has a great impact on the viscosity of the ink and the transfer effect is not good, especially for transition plates.

Example:

Such as Vida V0035 blue classic mini single bag.

(5) Installation tips

Transitional version, layered version superimposed by shallow net, small text version:

The appropriate angle is 30° to 40°, and the length of the scraper extending from the back of the blade is 5mm to 6.5mm.

Line version, full version or full deep web:

The appropriate angle is 45° to 60°, and the length of the scraper extending from the back of the blade is 5mm (adjustments may be made appropriately in special circumstances)

The distance from the contact point between the scraper and the plate roller to the contact point between the pressure roller and the plate roller should be smaller.

4. Things to note

(1) Wear gloves when installing and polishing the scraper to prevent scratches

(2) When sharpening an old knife, pay special attention to the gaps at both ends.

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