Do You Know What Is Dandy Roll?

What is Dandy Roll?

The dandy roll is a lightweight hollow roller wrapped in copper or stainless steel mesh, usually installed on the formed fabric surface after the first two or three vacuum suction boxes. The dandy roll have the ability to decorate the paper surface and endow it with the necessary watermark; Improve the uniformity of paper; In addition, the finishing roller can also play a role in destroying and eliminating bubbles in the paper web.

The Structure of Dandy Roll

◆  Dandy Roller Body

The dandy roll body is a shaft type with a surface width of: bearing center distance minus 400 mm. The roller body is made of all stainless steel material, and the keel is made of Ø 4 diagonal stainless steel wire, Ø 5 horizontal stainless steel wire, and a middle reinforcement ring. The plate thickness is 2 mm, and the outer steel strip is 1.2 × 7 vertical spiral wound and welded, thereby improving the rigidity and hole opening rate of the roller body and facilitating dehydration and cleaning. After welding, vibration and heat treatment methods are used to eliminate welding stress to ensure that no deformation occurs during production and use. Then, it is roughly ground and finely ground, and wrapped with a 40 mesh 316L stainless steel mesh. This structure is not easy to loosen and has strong rigidity, suitable for producing rollers with large diameters and long surface widths. To meet the current demand for high-speed and wide gauge paper machines.

◆ Spray pipe

The steam spray pipe is installed inside the dandy roll body, with a hole diameter of 1 mm, double row holes, a row spacing of 3 mm, and a hole spacing of 6 mm. The steam usage pressure is 0.1 MPa (1-2kgf/c ㎡) or determined according to the process requirements, and the spray direction can be adjusted to 45°.

◆ Water tank

The water receiving tank is made of stainless steel material and is located inside the watermark roller body. In order to effectively receive the water droplets splashed by the high-pressure moving water spray pipe, the water receiving area on one side of the water receiving tank is enlarged and adopts an internal cavity assembly and disassembly type.

◆ Connect the transmission cover

Used for connecting the roll body with the transmission universal joint, the spray pipe, water receiving groove, and high-pressure moveable spray pipe inside the roller body are fixed on the transmission side and are all on the bearings of this component; For the convenience of loading and unloading, when lifting the dandy roll, simply remove the universal joint flange on the end cover.

◆ Lifting device

The lifting and lowering of the dandy roll is achieved by the corrugated pneumatic tire of this component. Generally, the distance of pressing the mesh surface is 5-15 millimeters, which is determined by the process according to different paper types and quantitative conditions.

◆ Limit device

Used to limit the distance between the dandy roll and the forming fabric when lifting up and down, adjusted with a nut; During normal operation, the dandy roll bearing frame is supported by the lower nut to ensure the distance that the dandy roll presses down; When the machine is stopped, lift the dandy roll of the pneumatic tire away from the mesh surface, use a nut to limit the bearing frame within the range of the pneumatic tire stroke, and lock it with a pin.

◆ Water Connection Cover

This device serves two purposes: firstly, when the dany roll rotates at high speed, centrifugal force throws water droplets from the roller surface towards the water receiving outer cover; Secondly, there are three water scrapers that can flow fine fibers and spray water from the roller surface into the water receiving bucket and discharge them.

◆ Compressed Air System

The pneumatic box is equipped with a pressure reducing valve, an electromagnetic directional valve, and a manual directional valve. The external compressed air is connected to adjust the pressure, and the directional valve controls the rise or fall of the pneumatic tire. The operating pressure is 0.3MPa (2~6kgf/c ㎡).

◆ High Pressure Moveable Sprinkler Pipe

Move high-pressure water spray pipes inside the roller, arrange nozzles at 60mm intervals, and use needle shaped nozzles made of high-quality stainless steel and hard ceramic materials composite; To prevent nozzle blockage, a 100 mesh filter is installed at the inlet; Water pressure requirement: 0.3MPa (3-8kgf/c ㎡), swing stroke: ± 40mm, reciprocating frequency: 10 times/minute, adjustable spray angle; The transmission device adopts a micro gear reducer and a motor power of 180W.

◆ Transmission Department

Independently equipped with a transmission point, using frequency converter speed regulation, cycloidal pinwheel deceleration, universal joint output, and watermark roller can rise and fall freely.

◆ Electric Control Box

A single transmission point, frequency conversion speed regulation synchronized with the paper machine, with specific configuration as follows:

1. Speed control signal input, speed display;

2. Manual or automatic control, output, speed display;

3. Automatic roller lifting (when stopped or when the speed difference between the machine and the paper machine is too large).