Matters needing attention in surface treatment of sheet metal by automatic sandblasting machine

When using automatic sandblasting machine for sheet metal surface treatment, it is necessary to control the precautions from four dimensions: equipment safety, processing quality, environmental compliance and personnel protection to avoid equipment failure, processing defects or safety accidents, which can be divided into the following categories:

A, equipment operation and safety precautions

Pre-boot inspection is essential.

Confirm the status of all parts of the equipment: check whether the sealing of the sandblasting door is intact (to prevent abrasive splashing or dust leakage), whether the nozzle of the spray gun is worn (damage will lead to uneven sandblasting), and whether the abrasive conveying pipeline is blocked (blockage will lead to sudden pressure rise and there is a risk of pipeline bursting).

Test safety protection devices: such as emergency stop button, hatch interlock device (the equipment needs to be unable to start when the hatch is not closed tightly) and pressure overload protection valve (to avoid the air pressure exceeding the rated range of the equipment) to ensure that all devices are sensitive and effective.

Parameter setting needs to match sheet metal characteristics.

It is forbidden to set parameters "across the board": according to the sheet metal materials-such as aluminum alloy, galvanized sheet and other soft materials, it is necessary to use low pressure (0.3-0.5MPa)+ soft abrasive (plastic sand, glass beads) to prevent the surface of the sheet metal from sagging or coating damage; For hard materials such as carbon steel and stainless steel, high air pressure (0.5-0.8MPa)+ steel shot/alumina abrasive can be used to improve rust removal efficiency.

Control the time and angle of sandblasting: too long single sandblasting time will easily lead to excessive roughening of the sheet metal surface (affecting the subsequent spraying thickness); It is recommended to keep the injection angle at 30-60 (vertical injection will easily cause local wear, and if the angle is too small, the sandblasting strength will be insufficient).

Second, the processing quality control matters needing attention

Abrasive management should be standardized

Abrasives need "classified use+regular screening": abrasives with different materials and particle sizes cannot be mixed (for example, mixing fine glass beads with coarse steel balls will lead to uneven surface thickness); After use, impurities and debris are removed through the screening system (or manual screening) provided by the equipment, so as to avoid the abrasion abrasive from affecting the treatment effect.

The new abrasive needs to be sprayed for the first time: the particle size of the new abrasive may be deviated, so it needs to be sprayed on the waste sheet metal parts first to confirm that the surface roughness and cleanliness meet the requirements, and then the formal products are processed in batches.

Sheet metal positioning and fixing should be firm.

Avoid the displacement of the sheet metal during machining: select the appropriate fixture according to the shape of the sheet metal (such as flat plate, bent piece and special-shaped piece) to ensure firm fixation-if the sheet metal is loose, it will lead to missed spraying or repeated sandblasting in the sandblasting area, resulting in "negative and positive sides" (some areas are clean and some scales remain).

Special parts need to be protected in advance: if there are precise structures such as threaded holes and bearing positions on the sheet metal surface, rubber plugs and adhesive tapes should be used to cover them to prevent abrasives from entering the blocked holes or scratching the precise surfaces.

III. Precautions for Environmental Protection and Personnel Protection

Environmental compliance can not be ignored.

It must be equipped with a dust collection system: the automatic sand blasting machine will generate a large amount of dust (especially quartz sand and alumina abrasive) when it works, so it is necessary to ensure that the air volume of the dust collector is sufficient (matched according to the processing capacity of the equipment, usually the air volume per hour is not less than 1500m³), and the dust emission should meet the local environmental protection standards (such as the particle emission concentration ≤ 10mg/m), so as to avoid polluting the environment or causing the risk of dust explosion (when the dust accumulation reaches a certain concentration, it is easy to explode in case of fire).

Abrasive wastewater needs to be treated and then discharged: If wet automatic sandblasting machine is used (some models use abrasive+water for sandblasting), the generated wastewater contains abrasive residues and metal chips, which need to be treated by sedimentation tank and filtration system before being discharged. It is forbidden to directly discharge polluted water.

Personnel protection should be in place.

Operators must wear a full set of protective equipment, including dust mask (N95 or above, to prevent inhalation of dust from damaging the lungs), impact goggles (to prevent abrasive splash from injuring eyes), wear-resistant gloves (to prevent hands from touching sharp sheet metal or abrasive) and anti-static work clothes (to avoid electrostatic adsorption of dust and prevent oil pollution of sheet metal).

It is forbidden to operate illegally: it is forbidden to open the sandblasting hatch when the equipment is running (to prevent dust and abrasive from spraying out and injuring people); Non-operating personnel shall not approach the working area of the equipment to avoid touching the button by mistake or being injured by leaked abrasive.

Four, equipment maintenance and emergency treatment matters needing attention

Regular maintenance prolongs the service life of equipment.

Cleaning after daily shutdown: empty the residual abrasive (to prevent the abrasive from caking in the pipeline), clean the filter element of the dust collector (to avoid the suction reduction caused by the filter element blockage), and check whether the barometer and pressure gauge pointer are zero (long-term pressure will damage the instrument).

Replace wearing parts regularly: such as nozzles (usually replaced every 500-800㎡ sheet metal processing), sealing strips (at the joints of doors and pipelines, replace them in time after aging to prevent leakage), and bearings (bearings of conveying mechanism should be lubricated every month to avoid wear and seizure).

Emergency handling of emergencies

In case of abnormal equipment (such as abnormal sound, smoke and sudden pressure drop), it is necessary to immediately press the emergency stop button to cut off the power supply and air supply. After the equipment stops completely, troubleshoot the fault, and it is forbidden to run with fault.

In case of dust leakage, it is necessary to evacuate the personnel first, turn off the main switch of the equipment, and then cover the leakage area with wet cloth (to prevent the dust from spreading). Only after the failure of the seal is investigated and repaired can it be restarted.