Hook-type shot blasting machines are a common type of surface treatment equipment, widely used in industries such as automobile manufacturing, construction machinery, and casting and forging. This article introduces the machine from aspects such as working principle, equipment structure, applicable workpieces, technical parameters, selection points, and maintenance.
I. Working Principle
Hook-type shot blasting machines adopt a suspended operation method. The workpiece is suspended from the hanging device in the shot blasting chamber by a hook or lifting device, and the drive mechanism drives the workpiece to rotate at a constant speed inside the chamber. Shot blasters arranged at different positions in the chamber propel shot at high speed onto the surface of the workpiece. Due to the continuous rotation of the workpiece, the blasting coverage can cover the outer surface, internal cavities, and deep holes of the workpiece. After cleaning, the hook sends the workpiece out of the shot blasting chamber and into the unloading station.
Hook configurations can be divided into single-hook and double-hook types. The single-hook configuration is suitable for small to medium batch production, while the double-hook configuration allows for alternating operation of one hook cleaning inside the shot blasting chamber and the other hook loading and unloading outside, reducing equipment downtime and improving equipment utilization.
II. Equipment Structure
The hook-type shot blasting machine mainly consists of the following parts:
Shot Blasting Chamber
The shot blasting chamber is a sealed box structure with wear-resistant protective plates lining the inner walls to withstand repeated impacts from the shot. The chamber has a large door for workpiece entry and exit, equipped with a sealing device to prevent shot and dust from escaping. A collection hopper is located at the bottom of the chamber to collect scattered shot.
Hook and Hanging System
The hook consists of a lifting mechanism and a rotating mechanism. The lifting mechanism is responsible for feeding the workpiece into and out of the shot blasting chamber, while the rotating mechanism ensures the workpiece rotates at a uniform speed during the cleaning process. The load-bearing capacity of the hook is selected according to the weight of the workpiece, with common specifications ranging from 500 kg to 5000 kg. Dual-hook configurations have two independent hanging systems that can be used alternately.
Shot Blasting Unit
The shot blasting unit is the core component of the hook-type shot blasting machine, typically located on the side and top of the shot blasting chamber. Each shot blasting unit consists of an impeller, a shot distribution wheel, a directional sleeve, and a motor. The number, power, and arrangement angle of the shot blasting machines are determined based on the cleaning requirements of the workpiece. A common configuration is 2 to 4 shot blasting machines.
Shot Circulation System
The shot circulation system consists of a screw conveyor, bucket elevator, separator, and storage hopper. Scattered shot is collected by the screw conveyor at the bottom of the shot blasting chamber and sent to the bucket elevator, where it is lifted to the separator for screening and separation. Intact shot falls into the storage hopper for reuse by the shot blasting machines, while broken shot and dust are discharged.
Dust Collection System
The dust collection system consists of a dust collector, fan, and piping. The shot blasting chamber is maintained under negative pressure during operation, and dust-laden gas is drawn into the dust collector through the piping. The dust collector is typically a cartridge filter type, with a filtration efficiency of over 99.9%.
Electrical Control System
The electrical control system uses a PLC programmable controller equipped with a touchscreen interface. The system controls the lifting and rotation of the hook, the start and stop of the shot blasting machines, the operation of the shot circulation system, and the start and stop of the dust collector. The touchscreen displays equipment operating status, fault alarm information, and stores multiple sets of process parameters.
III. Applicable Workpieces
Hook-type shot blasting machines are mainly suitable for the following types of workpieces:
Complex-shaped workpieces
Including castings with internal cavities, deep holes, or complex curved surfaces, such as engine blocks, cylinder heads, gearbox housings, pump bodies, and valve bodies. The hanging and rotating method allows shot to enter the internal cavities and deep holes from multiple angles, resulting in more thorough cleaning.
Workpieces susceptible to impact
For example, precision-machined parts, threaded fasteners, and thin-walled castings. In a hook-type shot blasting machine, each workpiece is suspended independently, without contact with each other, avoiding surface damage or dimensional deviations caused by collisions.
Large single workpieces
Including large castings, forgings, welded structural parts, and frame-like parts. These workpieces are heavy and not suitable for batch processing in tracked equipment; the hook suspension method simplifies loading and unloading operations.
Workpieces requiring surface strengthening:
For example, gears, crankshafts, connecting rods, springs, and other parts subjected to alternating loads. Shot blasting can form a compressive stress layer on the metal surface, helping to improve the fatigue strength of the workpiece.
IV. Selection Considerations
When selecting a hook-type shot blasting machine, the following technical parameters and configuration options need to be considered:
Hook Load Capacity
Determine the rated load of the hook based on the weight of a single workpiece. The load capacity must cover the weight of the largest workpiece, with a certain safety margin.
Cleaning Chamber Dimensions
The effective working space of the shot blasting chamber must meet the dimensional requirements of the workpiece. It needs to be confirmed that the workpiece can pass smoothly through the doorway of the cleaning chamber and will not interfere with the inner wall of the chamber during rotation.
Shot Blasting Unit Configuration
The number, power, and arrangement angle of the shot blasters directly affect the cleaning efficiency and effect. For workpieces with complex shapes, it is recommended to configure multiple shot blasters to blast from different directions to reduce blind spots.
Hook Type
Single-hook configurations have a simple structure and are suitable for small-batch, multi-variety production. A dual-hook configuration allows for alternating operations, suitable for continuous production. Some machines also offer lifting hooks for easy loading and unloading of heavy workpieces.
Dust Collection System
Hook-type shot blasting machines should be equipped with a high-efficiency dust collection system to ensure dust emissions meet environmental standards. The dust collector type is typically a cartridge dust collector, and the appropriate airflow must be matched based on the shot blasting chamber volume and the power of the shot blaster.
VI. Maintenance and Upkeep
Daily maintenance of the hook-type shot blasting machine mainly includes the following aspects:
Daily Inspection
- Check if the shot inventory is sufficient.
- Listen for any abnormal noises from the shot blaster.
- Observe if there are any significant changes in the cleaning effect.
- Check if the dust collector differential pressure reading is within the normal range.
Weekly Inspection
- Check the wear condition of the shot blaster blades and directional sleeve.
- Clean impurities from the separator screen.
- Tighten all bolts.
- Check the operating status of the hook and lifting device.
Monthly Inspection
- Check the dynamic balance of the shot blaster.
- Clean the dust inside the electrical cabinet.
- Check the tension of the elevator chain and lubricate it appropriately.
- Check the idler rollers and drums of the conveyor system.
Quarterly Inspection
- Test the shot specifications, screen out waste shot, and replenish with new shot.
- Thoroughly clean the dust collector filter media.
- Check the motor insulation performance and bearing condition.
VII. Safety Precautions
- Before performing any maintenance operations, always disconnect the main power supply and post warning signs.
- When entering the shot blasting chamber, wear a safety helmet, goggles, and a dust mask.
- Use lifting equipment when replacing heavy components; manual handling is prohibited.
- After maintenance, conduct a no-load test run for a period of time to confirm there are no abnormalities before putting the machine into production.
- Operators should be trained and familiar with the equipment's operating procedures and safety requirements.
VIII. Summary
Hook-type shot blasting machines are suitable for workpieces with complex shapes, susceptible to impact, and with large individual weights. They achieve surface strengthening while cleaning. When selecting a model, the hook's load-bearing capacity, cleaning chamber size, and hook configuration should be determined based on the workpiece's weight, dimensions, shape complexity, and production volume. Establishing a regular inspection system during daily use can reduce the failure rate and extend the equipment's lifespan.
For further information on specific model technical parameters or selection advice, please provide workpiece drawings or on-site working condition information for a targeted evaluation by the technical team.
