New technology of spring surface treatment for the

New technology for surface treatment of die spring Abstract: the mold is the main process equipment for the industrial production of ordinary copper strip to be processed into special-shaped copper strip with thick middle and thin sides. The development of modern industrial products and the improvement of technical level largely depend on the development level of mold industry

relaxation experiment

the mold is the main process equipment in industrial production. The development of modern industrial products and the improvement of technical level largely depend on the development level of mold industry. Since the Second World War, the improvement of automation has led to the rapid development of foreign molds. Although China is a big country in mold production, it is not a powerful country in mold manufacturing. For the spring matched with the mold, this detail is also the key to achieving quality. It will affect the service performance of the whole set of dies

I majored in surface treatment engineering and made a market survey on the surface treatment of die springs, that is, rectangular springs. Find the following problems and put them forward for discussion

the spring surface is identified by various paint layers, such as yellow paint for light and small loads; Light load is indicated by blue paint; China and Netherlands use red paint to indicate; Heavy load reuse of coffee paint

performance analysis: a good paint layer to match the spring surface treatment can kill two birds with one stone. Color is used to identify various technical parameters, which is convenient for industrial production and operation, and better ensures the anti-corrosion performance of the spring surface

at present, the main manufacturers that successfully use the above methods are many foreign manufacturers, such as Japan Dongfa company

in China, there are only a small number of effective visits from manufacturers. At present, there are mainly some fixed technical requirements. For example, imported materials are adopted to reach the foreign level, but there is a significant gap in the surface treatment effect of the whole spring

manual painting is generally used in China, which may cause sagging, missing spraying, poor combination and poor rust prevention ability. Due to the limitations of its own process, a large number of products have to be repainted

electrophoretic paint is used abroad. In a water-soluble paint bath, the workpiece is used as the cathode, and a certain voltage and time are applied to form a uniform thickness of paint layer on all surfaces of the spring, which can then be cleaned and dried. Its appearance is clean and bright, without particles and bottom exposure, its adhesion is not easy to fall off, and its hardness is h. If the polyurethane cathodic electrophoretic paint of LVH company in Britain is used, its softness is quite good. The operating environment has no strong solvent smell, less air pollution, and the wastewater treatment and discharge process is simple. As long as the pH is adjusted to settle the resin of the electrophoretic paint, and then discharge the clean water

we designed the process flow for a domestic manufacturer: forming spring → shot peening → → upper hanger → alkaline degreasing → double water washing → (slight acid 1% neutralization) phosphating → double water washing → double deionization water washing → polyurethane color electrophoretic paint for cathode system → recycling → double water washing → washing aid → baking and solidification → lower hanger

results:

shot peened particles will be clamped in the gap between the two ends of the spring

shot peening leads to rough surface, and the paint layer should be thickened accordingly, so as to have a bright and flat appearance with micron thickness, which in turn leads to the reduction of the shrinkable thickness of the spring

phosphating will cause hydrogen embrittlement and reduce the service life of the spring

improvement process: forming spring → alkaline polishing oil removal → centrifugal water dropping → hanging → alkaline oil removal → double water washing → (slight acid neutralization 1%) phosphating → double water washing → double deionization water washing → polyurethane color electrophoretic paint of cathode system → recycling → double water washing → washing aid → baking and curing → lower hanger

analysis:

from the government level,

the finishing (finishing) process is to put the spring directly into the inclined centrifugal or spiral vibrating, eddy current and other series of finishing machines, and add an appropriate amount of abrasive, abrasive and water stock Beijing Lear (002392) carries out finishing. The polished surface is smoother than the shot peened surface.

in addition, traditional processes such as degreasing, cleaning, acid pickling, phosphating, dehydrogenation, etc. are reduced, the production process is simplified, the spring has less corrosion opportunities in the production process, and acid pickling is not required. The thickness of paint on the surface can be controlled at about 10 microns.

the author uses Haojin fine chemicals (Shanghai) The Jililong cathodic electrophoretic paint of the company was tested. It has good performance in all aspects and coating rate: when the coating is 10 microns, each kilogram of paint can be coated with a square meter. Salt spray test: H

however, the strength of the spring itself may be reduced by subtracting the shot peening process. It is best to select the steel shot with appropriate 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 burning paint layer, and then use shot blasting to clean the surface, but the operation process causes considerable pollution, and fire is easy to occur during manual operation

use concentrated sulfuric acid to carbonize the paint layer, but the strong acid itself will cause hydrogen embrittlement, which is not applicable to the spring

using KRT paint remover and swelling method to peel off the paint layer without damaging the spring matrix is an advanced method with simple operation. However, using commercial paint remover may lead to cost increase, but if the scrap rate is reduced, the overall cost will not increase