1. Overview of air knife

1.Dak (dynamic air knives):

The function of the air knife is to wipe off the zinc on the steel belt at the outlet of the zinc pot, and control the thickness of the zinc layer through the zinc layer control system. This function is performed by a jet of air generated between the two lips of the air knife. The thickness control method of the steel strip surface is based on the adjustment of the gas pressure of the two air knives on each side of the steel strip and the distance between the knife lip and the steel strip (these functions are activated when the operator activates this function in the hmi or selects automatic). The thickness control method of the steel strip surface is based on adjusting the screw and nut to adjust the cross-sectional area of the two air knife lips on each side of the steel strip. (After the cross beam is disassembled, it is directly adjusted by manual rotation) The air knife is driven by vertical and horizontal movement servo motors to complete vertical and horizontal movements. The air knife has undergone many improvements since its inception: the injection medium was changed from superheated steam to compressed air; secondly, in order to obtain an ideal coating cross-section, the uniform slit shape at the mouth was changed to an uneven slit shape that is narrow in the middle and wide at both ends; thirdly, , an analog electronic computer is generally used to control the air flow of the air knife to automatically control the thickness of the zinc layer. Annular air knife

Air knife equipment

The main equipment includes sinking rollers, stabilizing rollers, air knives, etc.

2. Sinking roller device

The sinking roller device consists of three parts: a sinking roller immersed in the zinc liquid, an adjustment system above the zinc liquid level, and a cross-frame welding structure.

(1) Operation of sinking roller

The sinking roller in the zinc pot is a passive steering roller, driven entirely by the friction between the strip steel and the roller surface. During the production process, the sinking roller should always be in operation. Especially when producing thin gauge strips, tools should be used to frequently test whether the sinking roller is running.

Methods to prevent the sinking roller from stalling:

a. Process grooves on the surface of the roller to increase friction.

b Use a large diameter sinking roller. The larger the diameter of the sinking roller, the larger the wrapping angle between the strip and the roller, and the greater the friction force generated.

c When producing thin strips, the temperature of the preheating furnace or reduction furnace can be appropriately reduced to ensure sufficient strip tension, or the operating speed of the unit can be appropriately reduced so that the sinking roller is always in operation.

(2) The correction function of the sinking roller

There are generally two methods for the sinking roller to prevent strip deviation: one is to make the sinking roller have a certain convexity, that is, the middle of the roller diameter is larger than the two sides. However, the guiding effect of the sinking roller crown is only.

This can only be achieved when the thickness of the strip is uniform and the plate shape is good. In addition, this kind of roller with convexity has certain shortcomings, that is, the strip cannot move left and right on the roller flexibly. When one end of the roller is scarred, it is easy to produce impressions on the surface of the strip. Therefore, in production practice, most units do not use this kind of convex sinking roller, but use the method of adjusting the slope of the sinking roller to correct the deviation of the strip: when the strip deflects to a certain end, it is The other end of the sinking roller descends until the strip returns to the centering position, and then the sinking roller remains horizontal. The principle is the same as the crown roller guide principle. Super air knife