Painting equipment automatic spray gun principle selection troubleshooting

Painting equipment automatic spray gun principle selection troubleshooting

The principle of automatic spray gun in painting line:

The interior of the automatic spray gun of the painting equipment has a pneumatic piston mechanism, a stainless steel spray needle is installed above the piston, and a set of high-tension spring is installed behind the piston. When the compressed air stops supplying, the spring pushes the piston and the spray needle forward. At this time, the spray needle and the nozzle are closely matched with high precision to block the passage of liquid. The pressure of compressed air will push away the piston, so that there is a gap between the spray needle and the nozzle, so that the liquid is ejected, and the liquid immediately contacts with the atomizing air to produce atomization effect.

Air gun

Air gun construction

Selection and adjustment of automatic spray gun in painting line:

Automatic spray gun selection:

The selection of spray gun should be noted that the primer mainly plays the role of filling in the coating and increasing the thickness of the coating, so the particle size of the primer is larger, the viscosity is larger, and the proportion is larger, emphasizing that the amount of paint should be large, so the spraying primer should choose a spray gun with a large caliber nozzle, and the corresponding paint storage irrigation should be larger. The spray paint, in terms of the degree of atomization requirements are high, often choose a small caliber and better atomization spray gun. The nozzle of the common spray gun has different calibers, including 0.6mm, 0.8mm, 1.2mm, 1.3mm, 1.5mm, 1.6mm, 1.8mm, 2.0mm, 2.2mm, 2.5mm and other models, which can be selected according to the size of the paint sprayed and the object sprayed. For example: diameter 2.0-2.5mm, commonly used to spray coarse particle size, larger viscosity primer or large area spraying; Diameter 1.5-1.8mm, mainly used to spray paint; Diameter 0.6-1.3mm, mainly used for spraying small parts or crafts.

Automatic spray gun adjustment of painting line:

The adjustment of automatic spray gun of painting equipment is mainly to point out the adjustment of gas volume and paint output. These are two interrelated main factors. The gas output is too small, it is not easy to atomize the paint, so that the paint drops will make the film uneven. The size of the paint output is corresponding to the size of the gas output, and the appropriate gas output and the corresponding paint output should be adjusted before spraying, so that the paint spray is well atomized and evenly sprayed on the surface. Adjust the spray gun to listen to (listen to the sound of the air flow, know the size of the air flow), and look at the second (look at the atomization degree of the spray gun mouth paint and the size of the fan area). Several important parameters of the spray gun are as follows: air pressure: The air pressure of the spray is generally (0.4-0.6Mpa); Spray width: the width of the spray on the working surface is about 10cm; Spraying distance: When spraying, the distance between the nozzle and the sprayed object is 15-20cm; Moving speed: the moving speed of the spray gun is generally 30-60cm/ second; Overlap range: when spraying, the overlap range of each shot is 1/2-1/3 (except crack paint); Spraying Angle: The Angle between the nozzle and the sprayed object is generally 90°.

Painting equipment automatic spray gun common problems and solutions:

Sometimes there are some problems in the process of using the automatic spray gun in the painting line. Now the phenomenon of the spray gun is analyzed in detail, and the reasons are analyzed according to the phenomenon, and the solution is found.

Phenomenon: The shape of the spray amplitude is skewed to one side

Cause: gas cap center hole or atomization hole blocked

Countermeasures: 1, clean the atomizing cap 2, replace the atomizing cap

Phenomenon: Deviation to the left or right

Reasons: 1, the fan control hole on the side of the gas cap is blocked 2, the gas cap is damaged

Countermeasures: 1, clean the atomizing cap 2, replace the atomizing cap

Phenomenon: The central spray width is too thick

Reasons: 1, the spray coating viscosity is too high 2, the spray pressure is too low 3, the aperture of the nozzle and the thimble increase and decrease due to wear

Countermeasures: 1, reduce the viscosity of the coating 2, increase the spraying pressure 3, replace the nozzle set

Phenomenon: Jet splitting

Reasons: 1, the paint viscosity is too low 2, the spraying pressure is too high 3, the inner diameter of the fan control hole is too large 4, the paint is not enough 5, the atomizing air channel is blocked

Countermeasures: 1, increase the paint viscosity 2, lower the spraying pressure 3, replace the nozzle set 4, add enough paint 5, clean the air channel of the spray gun

Phenomenon: Jump gun

Reasons: 1, the nozzle is not tightened or not installed 2, the gun needle sealing kit is loose 3, the spray gun connection nut is loose (lower spray gun) 4, the paint in the pot is less than 5, the nozzle set is damaged

Countermeasures: 1, tighten the nozzle or clean and install the nozzle set 2, tighten the thimble sealing kit 3, tighten the connection nut 4, add paint 5, replace the nozzle set

Phenomenon: The spray width is heavy up or down

Reasons: 1, the nozzle, thimble or air cap of the air outlet is blocked by debris 2, the gas cap or nozzle is damaged

Countermeasures: 1, clean nozzle set 2, replace nozzle set

Phenomenon: can not spray paint or a small amount of paint

Reasons: 1, the air refill hole of the pot cover is blocked or the gas cap and suction pipe are seriously blocked 2, there is no paint in the pot 3, the thimble stroke is too small

Countermeasures: 1, clean the air supplement hole, gas cap and suction tube on the pot lid 2, supplement the paint 3, rotate the paint flow adjustment knob to increase the stroke of the needle valve

Phenomenon: Leakage of paint at the nozzle

Reasons: 1, the thimble seal nut is too tight 2, there is a foreign body inside the nozzle port 3, the nozzle and the thimble are not matched or damaged 4, the thimble aftertaste spring is broken or not installed

Countermeasures: 1, loosen the thimble seal nut 2, clean the nozzle 3, replace the nozzle set 4, replace the thimble return spring or install the upper thimble return spring

Automatic spray gun maintenance of painting equipment:

After the automatic spray gun is used, spray clean with the thinner of the sprayed paint until the spray gun paint channel is cleaned. Otherwise, the dry solid blockage of the paint in the gun will affect the normal use of the spray gun. Specific cleaning methods: close the compressed air, remove the paint storage, pour the paint inside the gun back into the paint storage, and pour the paint in the tank into the container; Pour about 1/4 volume of solvent into the paint storage irrigation for washing, fill the paint storage irrigation, connect the compressed air, repeatedly rock spray several times; Disassemble the nozzle, scrub clean with solvent and then install it; Wipe the paint off the gun.

The following points should be noted when washing the spray gun: use a soft brush when cleaning, prohibit the use of metal brushes, do not use hard objects to poke, scrape, prevent wear nozzle, so that the shape of the jet changes; Avoid the spray gun directly immersed in the solvent, to prevent the residual paint attached to the machine and dissolve the lubricating oil on the gun, can use a soft cloth with solvent; The knurled parts on the gun are adjusted by hand, avoiding the use of pliers tools; Drip lubricating oil regularly at the needle valve and gun pin; Regularly lubricate needle valve and needle valve spring with light grease or petroleum jelly, do not use silicone oil.