The surface treatment of the mold rectangular spring needs to be cautious

Existing molds are the main process equipment for industrial production. The development of modern industrial products and the improvement of technology level depend to a large extent on the development level of the mold industry. Although my country is a big country in mold production, it has never been a strong country in mold manufacturing. For springs that match the mold, this detail is also the key to achieving quality. Affect the performance of the whole set of molds.

The surface of the spring is identified by various paint layers, such as yellow paint for light and small loads; blue paint for light loads; red paint for medium loads; coffee paint for extremely heavy loads;

Performance analysis: A good paint layer is used to match the spring surface treatment. It can be described as two birds with one stone. The color is used to identify various technical parameters, which is convenient for industrial production and operation, and the anti-corrosion performance of the spring surface can be better guaranteed.

Currently, the main manufacturers that successfully use the above methods are many foreign manufacturers, such as Japan's Dongfa Company.

In China, only a small number of manufacturers have paid effective visits. At present, it is mainly due to some fixed technical requirements, such as the use of imported materials to achieve foreign standards, but there is an obvious gap in the surface treatment effect of the entire spring.

Manual spray paint is generally used in China, and the appearance will appear sagging, leaking, poor combination, and poor anti-rust ability. The limitations of its own process caused a large number of products to be stripped and reworked.

Electrophoresis paint is used abroad. The workpiece is used as a cathode in a water-soluble paint tank, and a certain voltage and time are applied to form a paint layer of uniform thickness on all surfaces of the spring, and then it can be cleaned and dried. . Its appearance is clean and bright, no particles, no bottoming phenomenon, good binding force and not easy to fall off, and good hardness of 3-4H. If the polyurethane cathodic electrophoretic paint from British LVH company is used, its flexibility is quite good. The operating environment has no strong solvent smell, less air pollution, and the waste water treatment and discharge process is simple, as long as the resin of the PH sedimentation electrophoretic paint is adjusted, and then the clean water is discharged.

We design the process flow for a domestic manufacturer: forming spring→shot blasting→→hanging tool→alkaline degreasing→double water washing→(micro acid 1% neutralization) phosphating→double water washing→double deionized water washing→ Cathode system polyurethane color electrophoretic paint→recycling→double washing→assisting washing→bake curing→under hanger.

Result:

The particles of shot peening will be clamped in the gap between the two ends of the spring.

Shot peening causes a rough surface, and the paint layer must be thickened accordingly to have a bright and smooth appearance, with a thickness of 10-20 microns, which in turn leads to a smaller shrinkable thickness of the spring.

Phosphating will cause hydrogen embrittlement and reduce the service life of the spring.

Improved process: forming spring → lye polish degreasing → centrifugal water drop → hanging → alkaline degreasing → double water washing → (micro acid neutralization 1%) phosphating → double water washing → double deionized water washing → Cathode system polyurethane color electrophoretic paint→recycling→double washing→assisting washing→bake curing→under hanger.

Analysis:

The finishing process is to put the spring directly into the inclined centrifugal, spiral vibration, vortex and other series of finishing machines, and add appropriate abrasives, abrasives and water for finishing. The surface after finishing is smoother than that of shot peening.

Moreover, traditional processes such as degreasing, cleaning, pickling, phosphating, dehydrogenation, etc. are reduced, the production process is simplified, and there is less chance of corrosion of the spring during the production process, so pickling is unnecessary. The thickness of the paint on the surface can be controlled at about 10 microns.

The author used Hawking Fine Chemicals (Shanghai) Co., Ltd.'s Geelylon cathodic electrophoretic paint for the experiment. It has better performance in all aspects and the coating rate: when the coating is 10 microns, 45-50 square meters per kilogram of paint can be coated. Salt spray test: 500-1000H.

But subtracting the shot peening process may reduce the strength of the spring itself. It is best to choose a steel shot with a suitable diameter according to different spring specifications, such as the size of the gap, to avoid the steel shot being caught in the spring gap.

Removal method of unqualified paint layer:

At present, some factories use oil to burn the paint layer, and then use shot blasting to clean the surface, but the operation process causes considerable pollution, and the manual operation process is prone to fire.

Use concentrated sulfuric acid to carbonize the paint layer, but strong acid itself can cause hydrogen embrittlement, so spring is not suitable.

The use of KRT paint remover, the swelling method, peels off the paint layer, does not damage the spring substrate, simple operation, is a relatively advanced method, but the use of commercial paint removers may increase the cost, but if the scrap is reduced Rate, the overall cost will not rise.