LONGFA™

Corrosion protection for steel products

Pretreatment lines combine the pre-heating, blasting, painting and drying of workpieces (e.g. steel sheets, profiles) in one automatic line.

Pretreatment lines are ideal when there is a long manufacturing or storage time between shot blasting and final coating. To prevent re-rusting, timely spraying of the primer will ensure corrosion resistance for several weeks.
 
Sheet widths up to 5500 mm and roller conveyor speeds from 1.0 to 6.0 m/min.

       「 Available options 」

                         ● Traverse loading and unloading device

                         ● Electric heating device

                         ● Flame heating device

                         ● Rainwater cleaning device

                         ● Sweeping device

                         ● German original import shot blasting machine

                         ● RTO

                         ● Coding machine

                         ● Monitoring System

                         ● Highly automated control system

「 Process flow 」

The workpiece is conveyed along the feeding roller conveyor, preheated, and arrives in the shot blasting room to start the shot blasting process. After shot blasting, the shot cleaning device will clean the steel shot on the surface of the steel plate, and then in the paint booth for primer spraying, and then in the drying room on the plate chain conveyor to be fully dried. Finally they will be sent out by the discharge conveyor roller. There they are either removed or sent out by a traverse down feeder.

LONGFA™

▍Common configurations of pre-processing lines

Traverse loading device → feeding conveyor roller → rain cleaning device → pre-heating device → shot blasting treatment → shot circulation system → dust collector → paint spraying room → paint mist treatment → drying room → discharge conveyor roller → traverse loading device

● Shot blasting systems

The shot blasting system is the key in the pretreatment line. Steel plates are blasted to remove rust and oxidation. All machines are equipped with highly efficient blast machines that allow complete cleaning of the steel plate in the blast chamber, obtaining a surface roughness of approximately Rz30-75μm and a standard cleaning quality of Sa2.5.

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▍Spraying system

Due to the often long manufacturing or storage time between blasting and final coating, the workpiece is coated with a fast-drying temporary anti-corrosion primer in the spray booth during the spraying process (coating thickness of approximately 15-25 μm).
We use an imported painting system to ensure satisfactory painting results.
This coating is the most expensive sub-process in the entire corrosion protection range, however, its ability to accurately control the coating process can save the customer six figures per year.

Height, width and distance measurement system

In front of the entrance of the shot blasting room, there is a pressure roller segmental width measurement device, photoelectric (laser) height measurement device.
According to the number of steel plate pressed down to measure the width of the pressure roller group, the steel plate to measure the width of sections, in order to control the number of blasting machine open, save energy, reduce the wear and tear of wear parts.

● Spraying technology

The identified workpiece data (position, width, height, etc.) is transmitted to the painting system, thus controlling the accurate opening and closing of the spray gun during the painting process, avoiding the phenomenon of empty spraying and saving a lot of paint.
The paint trolley uses an imported servo motor with servo drive and linear gear as drive. Long service life and more accurate control.
The painting system is usually equipped with 2-4 nozzles on each of the upper and lower guns to suit the different widths of the steel sheets to be painted.

LONGFA™

▍Drying room and plate chain conveyor

After painting, the steel plates are dried on a plate chain conveyor. The drying room uses a burner to generate heat, and then the hot air is continuously sent to the surface of the steel plate by a blower, so that even the paint with long drying time (such as water-based paint) can become dry quickly.
The plate chain conveyor adopts point support, after the steel plate and the plate chain contact, the two are relatively stationary, and the steel plate is driven by the plate chain for translational movement. The surface of contact between steel plate and plate chain is small, which will not damage the paint film on the steel plate.
The length of the drying room varies according to the type of paint, coating thickness and passing speed.
Choosing the correct drive motor is crucial. The correct drive shaft layout, drive and transmission ratio will ensure the smooth operation of the plate chain conveyor.

● Inlet and outlet conveying roller conveyor

The steel plates to be processed and treated are input and output here.
The roller conveyor inlet and outlet can be equipped with optional traverse conveyors, which can effectively avoid damage to the roller conveyor caused by the impact of heavy steel plates and optimize the work efficiency at the same time.

"The selection of equipment mainly depends on the following factors"

Workpiece dimensions and characteristics, productivity, operating parameters,
system and site requirements, material handling requirements, pollution/emission control,
Energy Conservation, Customer Requirements and Preferences

"Custom Solutions"

Longfa specializes in custom-designed reinforcement and surface treatment solutions to provide solutions to your challenges.
For section steel, flat steel, steel structure and some special workpieces, Longfa can design and provide roller conveyor shot blasting machine, hanging shot blasting machine, trolley shot blasting system, inclined roller shot blasting machine and steel plate pretreatment Lines, manual sandblasting booths, and dedusting ventilation systems.

"Standardized Equipment Solutions"

Longfa specializes in custom-designed reinforcement and surface treatment solutions to provide solutions to your challenges.
For section steel, flat steel, steel structure and some special workpieces, Longfa can design and provide roller conveyor shot blasting machine, hanging shot blasting machine, trolley shot blasting system, inclined roller shot blasting machine and steel plate pretreatment Lines, manual sandblasting booths, and dedusting ventilation systems.