Improvement of flatness in corrugated board production practice (3)

Cardboard is negatively arched horizontally

Known: face paper is 200g/nf B grade imitation kraft paper, moisture content of 8%; pressure 1. OMpa/c nf; production line speed 50m/min.

ways to improve:

(1) The length of the heating surface of the surface (clamp) tiles through the preheater is increased by 0.9 to 1.4, 0.6 to 1.12 times, respectively.
(2) The paper reduces the length of the preheater heating surface or sprays it with steam.
(3) The production line speed increased to around 60m/rain. Cardboard is arched vertically

ways to improve:

(1) Face paper reduces movement resistance in front of the three-layer preheater.
(2) Liva paper increases the resistance of the guide wheel and the tensioning wheel in front of the three-layer preheater. Appropriate adjustment of the original longitudinal arch can disappear.

Cardboard is arched vertically

Known: face paper is 200g/m2B grade kraft paper, moisture content of 13%; (clamp) tile paper is 150g/m2 high-strength corrugated paper, moisture content of 10%; inside paper with 200g/m2 B grade imitation kraft paper, moisture content of 8% Pressure 1. OMpa/cm2; production line speed 50m/rain.

ways to improve
(1) The length of the heating surface of the surface (clamp) tile through the preheater is increased by 0.9 to 1.4, 0.6 to 1.1 times, respectively.
(2) The paper reduces the length of the preheater heating surface or sprays it with steam.
(3) The production line speed increased to about 60m/min. Cardboard is arched vertically

ways to improve

(1) Face paper reduces movement resistance in front of the three-layer preheater.
(2) The tension in the tension of the Riva line in front of the three-layer preheater increases the resistance to movement.

Cardboard is positive and negative arched

Because there are two types of positive and negative arches, different methods of improvement only indicate the common transverse positive and negative arches.

Known: face paper is 180g/m2 kraft paper, water content 8 value 14%; air pressure is 1.1Mpa/c m2; production line speed 70m/min improved method

(1) Partially steamed sprayed paper in the transversely arched area
(2) Local steam spray in the transversely negatively arched area.
(3) The production line speed is reduced to about 60m/min.
(4) Perform 180 on Riva paper. Direction adjustment.

In addition, there is a way to make up for this. That is, for paperboards with a large part of arches that have just been manufactured from the production line, a stack of positive and negative stacks of about 10 sheets is placed on top of the rear pressure plate, so that the cardboard is subjected to positive and negative reactions during the storage of semifinished products. Flattening of the external force, after a few hours (according to the plant ventilation, cooling conditions) can achieve a better flatness.

Assumptions and suggestions

At present, with the improvement of the automation level in the packaging industry, multi-functional operations such as cardboard printing, die cutting, slotting and filleting, bonding, binding, and binding, and machine packaging lines for cartons are widely used, and the requirements for flatness are increasing. The higher the paperboard, the unqualified paperboard will be automatically shut down or withdrawn from the packaging line. We believe that there should be a specification for the flatness of corrugated board so that it is easy for operators and quality inspectors to follow the operation inspection and to help control the quality of the process.

The flatness of the corrugated board shall be measured after being placed horizontally without any external force, with the chord height being a measure. Flatness is divided into 3 levels:

The first-class accuracy is suitable for the production of multi-functional machines such as die-cutting, slot-cutting and angle cutting, and is used for high-precision machine-packed cartons.

The secondary precision is suitable for the production of imprinting die-cutting machines, and is used for high-precision packaging cartons;

The three-level accuracy is suitable for single-machine production such as printing, slitting, indentation, and slotting machines, and is used for packaging cartons that are generally accurate.

Improve and improve corrugated board production line equipment

(1) The preheater required for each layer of paper, especially the preheater needed for the surface paper, should be able to adjust the length of the heated surface of the paper (wrap angle);
(2) There must be sufficient space for each paper to send moisture after passing through the preheater, especially to ensure that the paper is distributed in the space where moisture is emitted;
(3) Fan ventilation shall be provided in the area where the paper is preheated to distribute moisture.

(author/Shi Wen)
China Packaging News--Paper Packaging Weekly

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