Treatment of the problem of the paint at the bottom of the barrel in the electrostatic painting of steel drum

Treatment of the problem of the paint at the bottom of the barrel in the electrostatic painting of steel drum

Yang Wenliang

Our factory has been using electrostatic painting for 15 years, and has carried out two large-scale technical transformations in the middle, and has realized a fully automatic production line. Then, the cleaning equipment before the coating of the steel drum was modified, so that the coating quality of the outer surface of the steel drum was greatly improved, which was well received by users. However, with the increasingly fierce market competition and the continuous improvement of user requirements, the quality of steel drum coatings in our factory has also appeared some problems that cannot meet the requirements of users. At the beginning of the year, the user raised the problem of the paint at the bottom of the barrel. We solved the quality problem satisfactorily through careful analysis and processing. The user was very satisfied and said happily: "It is not the same, it is not the same!"

First, the analysis of the reasons for quality problems

The phenomenon of quality problems is: on the bottom surface of the steel drum after painting and drying, it is often found that there is a piece of paint accumulation phenomenon, which affects the appearance of the outer surface. These paints are less than three or more, more than ten At different sizes, it usually presents 5~10 mm protruding dots.

In order to find out the cause of the problem, we carefully followed the investigation from the beginning of the steel barrel painting until the drying process, and found that the problem of the paint on the bottom of the barrel was caused by the following reasons: in the spray booth, due to the spray of the nozzle The paint mist is constantly adsorbed on the rack rack and the hanger. After too much adsorption, it will flow down or drip from the rack and the hanger. The paint will drip on the bottom of the bucket and form a convex product after drying. Paint spots.

To put it simply, our painting method is electrostatic painting. The steel barrel conveying method is chain suspension conveying, and the steel barrel bottom is upright into the “Ω”-shaped spray chamber for painting. The steel drum is caught by the three-claw hanger on the bottom flange of the bucket. The rotation of the steel drum in the spray booth is generated by the transmission of the rail gear on the hanger and the "Ω"-shaped rack in the spray chamber. The spray disc is located in the center of the spray chamber, and is rotated by the pneumatic motor drive, and is moved up and down under the driving of the cylinder. The movement stroke is slightly larger than the height of the steel drum, so that the steel bottom is attached with paint.

Second, the method test to solve the quality problem

In order to solve the problem of paint accumulation at the bottom of the barrel, we have taken a series of measures to carry out the test. The test methods and results are as follows:

1. In order to solve the problem of dripping of paint on hangers, we implemented two sets of methods for timed replacement of hangers. Since the hanger will absorb the paint every time it passes through the spray booth, it will be solidified on the hanger after drying. Only when the thickness of the paint on the hanger is large and there is a downstream nozzle, the paint can be dripped, generally normal. In the case of production, the replacement of a hanger can produce about 10,000 barrels.

2. Since the paint on the rack of the painting room is not dried, it will drip slightly when it is adsorbed. The newly processed rack will not spray 200 barrels, which means that there is dripping. In order to make the racks do not drop paint, it is necessary to find a way to make the paint not adsorbed on the rack. For this purpose, we first lengthen the length of the hanger to reduce the height of the barrel during painting, so that the highest point of the nozzle can be lowered at any time, thus avoiding the contact between the paint mist and the rack and reducing the rack suction. Paint, but the effect is not perfect, because there is always a scattering of paint mist, the problem of dripping has not been completely solved.

3, in order to reduce the paint mist flying up to the rack, we set a plastic plate cover 150mm on the spray plate to reduce the paint fog. After the test, it was found that the rack paint was significantly reduced, and 400 to 500 barrels could be produced before the rack began to paint, but the rack could not be dripped, and satisfactory results could not be achieved.

4. In order to better reduce the adsorption of the paint mist to the rack, we placed a baffle between the rack and the spray plate. The baffle is made of plastic plate and bent into the shape corresponding to the shape of the rack. Shape, after the test, although the accumulation of the rack is greatly reduced, the paint mist adsorbed by the baffle starts to paint after a period of production, which proves that the effect is not satisfactory.

5. Through the above tests, we realized that in order to completely solve the problem of paint on the bottom of the barrel, it is obviously impossible to make obstacles to prevent the paint fog from rising on the existing equipment. To this end, we tried to change the rotation method of the steel drum in the spray booth and remove the structure of the rack drive. We studied the inertial rotation method, that is, when the steel drum is about to enter the spray booth, the electric drum is used to rotate the steel drum. When entering the spray booth, the steel drum has not stopped rotating until it is sprayed. When the spray booth was out, the steel drum stopped slowly. This method works well and directly prevents the occurrence of rack paint.

Third, conclusions and feelings

Through a large number of tests and analysis, we finally found a better solution: two sets of hangers were regularly replaced to solve the problem of paint dripping; the steel drum inertial rotation method was used instead of the rack drive structure. The problem of rack paint.

From this small reform, we realized that to solve problems, sometimes we should not just focus on the existing conditions, don't be afraid of difficulties, and don't have the idea of ​​perfunctory things and dealing with errands. Think more broadly, and dare to break the rules of the status quo. Only in this way will there be more and better ways to solve the problem.