What Does The Core Shaft Do On The Coater

The coating machine is mainly used for the production of surface coating process of film, paper, etc., this machine is to coat the substrate in rolls with a layer of glue, paint or ink with specific functions, etc., and cut into sheets or rewind after drying. This process requires precise control of the tension and position of the material to ensure that the coating is uniform and that wrinkling or breakage is avoidedCrack. The inflatable shaft may play a role here to support and hold the coil. The specific role of the inflatable shaft in the coating machine: mainly including supporting the coil, adjusting the tension, changing the roll quickly, adapting to different material widths, protecting the surface of the material, etc.

Let's start with the air expanded axis:
The inflatable shaft is a kind of rewinding and unwinding shaft that can be expanded on the surface after high-pressure inflation or a convex key strip to expand the paper tube or cylinder; When deflated, the surface part will retract rapidly. The use of the inflatable shaft is very convenient and fast, only the user needs to provide their own air source, the air pressure is controlled in the range of 6-8kg, when the reel core needs to be locked, as long as the air gun is inflated on the air nozzle on the inflatable shaft, it can be completed, and when the reel core needs to be loosened and discharged, the sliding air core on the air nozzle is deflated by hand. The most common types of slug and tile shafts used in industrial winding and unwinding production:
1) Leaf Type air expansion shaft (plate type inflatable shaft): the expansion is the whole plate, the fulcrum is evenly dispersed, and the force is uniform, which can be applied to machinery with high winding precision or lighter winding items, such as: drying machine, flexo printing machine, gravure machine, trademark printing machine, etc.
2) The scope of application of the convex key inflatable shaft includes: the key bar inflatable shaft expands up a single key bar, the fulcrum spreads to each key bar, balances the force, and the inflatable shaft can be applied to items with heavy mechanical winding capacity.
3) Multi bladder type air expanding shaft adopts a multi-balloon design, and the length of the airbag is about the same as the length of the main body of the inflatable shaft. This kind of inflatable shaft is suitable for the rewinding work of high-precision slitting machines, especially some narrow film coils.

What does an pneumatic expanable shaft do on a coater? Our main functions are as follows:
1) Core function: fixation and transmission of coils
Quick clamping: Through inflation and expansion, after expansion, the key bar or air bag of the inflatable shaft will be tightly attached to the inner wall of the coil, and it can be adapted to reels with different inner diameters (such as 3 inches, 6 inches, etc.) without mechanical adjustment, which greatly shortens the roll change time.
Uniform support: After expansion, it provides 360° uniform force in the whole circumferential direction, which avoids the deformation or eccentricity of the coil caused by local pressure of the traditional mechanical shaft, and ensures the smooth operation of the material during the coating process.
2) Tension control and process stability
Basis of tension adjustment: The coating process is extremely sensitive to the tension of the material (e.g., the coating of lithium battery pole pieces requires an accuracy of ±1%). As the core component of unwinding/rewinding, the inflatable shaft cooperates with magnetic particle brakes and servo motors to achieve precise closed-loop control of tension.
Anti-slip and anti-offset: The high friction of the inflatable shaft can prevent the coil from slipping or transverse deviation when running at high speed (such as more than 200m/min), and avoid uneven coating thickness or edge overflow.
3) Adapt to complex process requirements
Unwinding shaft: Supports uncoated substrates (e.g. PET film, copper foil) to ensure stable unwinding.
Rewinding shaft: Carrying the coated finished roll, it is necessary to ensure that the winding is neat and free of loose layers.
Intermediate transition shaft: In double-sided coating or lamination processes, for material steering or tension damping.
Material compatibility: The surface of the inflatable shaft can be customized with rubber layer, polyurethane coating, etc., to avoid scratching fragile substrates such as film and foil.
4) Automation and efficiency improvement
Automatic roll change: In the fully automatic coating machine, the inflatable shaft works with the A/B roll switching system to achieve non-stop roll change and reduce production interruptions.
Lightweight design: The inflatable shaft made of aluminum alloy can reduce the moment of inertia and is suitable for high-speed coating equipment (e.g., the coating line speed of photovoltaic backsheet can reach 300m/min).
5) Special scene application
Wide coating: The ultra-wide coating machine (such as the width of more than 2m) needs multiple inflatable shafts to be supported in parallel to disperse the weight of the coil and prevent the shaft from bending.High-temperature environment: Some coating processes involve oven temperatures (e.g., above 150°C), and inflatable shafts require high-temperature seals and special materials (e.g., silicone airbags) to maintain stability.

What are the factors that affect the quality of the coating? Man, machine, material, method, and environment all exist, but the basic factors are several conditions directly related to the coating process, namely coating substrate, adhesive, coating steel roller/rubber roller and laminating machine, etc,as follows:
1) Coated substrate: mainly material, surface characteristics, thickness and uniformity.
2) Adhesive: mainly its working viscosity, affinity and adhesion to the surface of the substrate.
3) Coating steel roller: It is not only the direct carrier of the adhesive, but also the supporting reference of the coating substrate and the rubber roller, so it is the core of the entire coating mechanism. Its shape and position tolerance, rigidity, dynamic and static equilibrium quality, surface quality, temperature uniformity and thermal deformation all affect the uniformity of coating.
4) Coating rubber roller: rubber roller refers to an important variable of coating quality, and its material (such as adhesive layer life), hardness, shape and position tolerance, rigidity, dynamic and static balance quality, surface quality, thermal deformation, etc. also affect the uniformity of coating.
5) Laminating machine: It is the basic platform for coating, in addition to the accuracy and sensitivity of the coating steel roller and rubber roller pressing mechanism, it also includes the design of the maximum running speed, the overall stability of the machine, etc.

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