Steel Plate Pretreatment Line

Hook-Type Shot Blasting Machine:

Hook-type shot blasting machines are highly efficient, flexible, and environmentally friendly surface cleaning and strengthening equipment widely used in industries such as casting, forging, machinery manufacturing, automotive, shipbuilding, and steel structure. Their core feature is the use of a high-speed rotating impeller to project metal pellets (shot) onto the workpiece surface, achieving the following objectives:

Cleaning: Removes impurities such as scale, rust, welding slag, grit, and old paint from the workpiece surface.

Rust Removal: Thoroughly removes rust from the metal surface to a specified cleanliness standard (e.g., Sa2.5, Sa3).

Strengthening: The impact of the shot creates a compressive stress layer on the workpiece surface, significantly improving fatigue strength and stress corrosion resistance, thereby extending the workpiece's service life.

Finishing: Achieve a uniform surface roughness, improving the workpiece's appearance.

Pretreatment: Provides a clean, ideal surface with a defined roughness for subsequent processes such as spraying and electroplating.

Structure:

Channel:

Constitutes the main frame of the machine and houses the shot blasting work area.

Typically constructed of thick welded steel plates, the inner wall is lined with a highly wear-resistant manganese steel shield or rolled Mn13 shield to resist impact wear from projectiles.

It is equipped with an observation window and maintenance door.

A sealed structure is designed on the top to prevent projectiles from splashing.

Shot Blaster:

The core component responsible for ejecting projectiles at high speed.

It primarily includes: an impeller, a shot-dispensing wheel, a directional sleeve, blades, a shield, and a drive motor.

Operating Principle: Projectiles flow into the shot-dispensing wheel, where they are accelerated by the rotating shot-dispensing wheel. They are then ejected through the windows of the directional sleeve and strike the high-speed rotating blades, which further propel the projectiles toward the workpiece at high speed. The ejection speed and shot volume can be controlled by adjusting the directional sleeve opening and the motor speed.

The number of blasting units is typically 1-8 or more, arranged on the side walls or roof of the chamber, depending on the chamber size and cleaning requirements, to ensure coverage of all workpiece surfaces.

Hook System:

A key component used to suspend and transport workpieces.

It includes an electric hoist or crane, a hook (with a self-rotating mechanism), a track system, and a rotary drive unit (motor reducer).

The workpiece is suspended from the hook via an electric hoist or crane.

After being conveyed into the cleaning chamber, the hook itself can rotate 360° continuously (or oscillate back and forth) to ensure that all surfaces of the workpiece are evenly impacted by the shot. Simultaneously, the entire hook system moves along the track, moving in and out of the chamber.

Shot Circulation System:

Screw Conveyor: Located at the bottom of the chamber, it collects and conveys the scattered shot and impurity mixture to the bottom of the elevator.

Bucket Elevator: Elevates the shot-to-sand mixture from the screw conveyor vertically to the separator at the top.

Shot-to-Sand Separator: A core component (typically an air separation/curtain type). It utilizes gravity, air, and screening to effectively separate usable, qualified shot from broken shot, dust, and impurities (sand, scale chips, etc.). Clean shot falls into the shot hopper, where dust is drawn into the dust removal system, and crushed shot and coarse impurities are discharged.

Shot hopper: Stores clean, separated shot.

Shot delivery duct/gate: Controlled by pneumatic or electric gates, the shot from the shot hopper is quantitatively and evenly delivered to the shot inlets of each shot blasting machine.

This system is responsible for collecting, separating, storing, and returning clean shot to the shot blasting machine.

Includes:

Dust removal system:

Ensures a clean working environment and meets environmental requirements.

Includes: settling chamber, cyclone dust collector (primary dust removal), cartridge dust collector or bag filter (secondary high-efficiency dust removal), fan, air duct, and chimney.

The fan creates negative pressure, drawing dust-laden air from the cleaning chamber into the dust removal system. Large dust particles are initially separated in the settling chamber or cyclone dust collector, while fine dust is filtered and collected by high-efficiency cartridge filters or bag filters. The purified air is discharged into the atmosphere through the chimney.

Electrical Control System:

Controls the entire equipment's operation, including hook travel and rotation, shot blaster start and stop, shot feed, dust removal system start and stop, and fault alarms.

A PLC (Programmable Logic Controller) is typically used as the core, coupled with a touch screen interface (HMI) for human-machine interaction, making operation convenient and intuitive. Different work programs can be set to accommodate different workpieces.

Safety Devices:

Door Limit Switch: Ensures the cleaning chamber door is securely closed before the shot blaster starts.

Emergency Stop Button: Located at key locations on the equipment.

Motor overload protection, phase loss protection, etc.

Shot circulation system blockage alarm, etc.

Technical Parameters:

Hook Load: 0.5 tons - 10 tons or more (customizable)

Cleaning Chamber Dimensions (WxDxH): Customizable based on workpiece and load

Number of Shot Blasters: 1-8 or more

Shot Blaster Power: 7.5kW - 30kW per unit or more

Total Power: Several tens of kW to several hundred kW

Shot Diameter: Commonly used Φ0.2mm - Φ2.0mm (steel shot, stainless steel shot, cast steel shot, cut wire shot, etc., selected based on workpiece material and cleaning requirements)

Cleaning Time: Several minutes to several dozen minutes (depending on workpiece complexity, contamination level, and cleaning level requirements)

Dust Removal Air Volume: Several thousand to several tens of thousands of cubic meters per hour