Double layer chromium electroplating processing process for conveying cylinder

Abstract

The invention provides a bilayer-chromium electroplating machining process for transport cylinders. The process comprises the following steps of making a CrO3 solution and an H2SO2 solution into an electroplating solution according to a certain proportion, putting the electroplating solution into an electroplating bath, heating to a certain fixed value, placing and preheating a transport cylinder in the electroplating bath, removing impurities, plating the transport cylinder with 20 to 30 microns of milky white chromium at 15 to 25 A of current per dm<2>, cooling the transport cylinder to a certain temperature, adopting a stepped current raising method to raise the current to 35 to 45 A per dm<2> and plating the transport cylinder with 280 to 300 microns of hard chromium, so as to obtain the transport cylinder plated with bilayer-chromium. The transport cylinder manufactured through the process can effectively prevent chromium layers from falling off caused by corrosion or prevent burst caused by insufficient bonding strength, thereby greatly increasing the life span of the transport cylinder.

Description

Technical field [0001] The invention relates to a processing technology of a conveying cylinder, in particular to a processing technology of a concrete conveying cylinder of a concrete pumping system of heavy construction machinery. Background technique [0002] Traditional conveying cylinders are mostly directly plated with a high-hardness wear-resistant chromium layer on the surface of the cylinder body. The chromium plating process is simple, the initial working temperature is low, and the process control is convenient. However, due to the high hardness of the chromium layer, large internal stress, and ductility It is very small, forming a large contrast with the substrate material with lower hardness and better ductility, and during use, due to the release of the internal stress of the coating, the original micro-cracks in the local coating expand and deepen to reach the substrate, resulting in concrete grout It penetrates into the cylinder body and forms a corrosion cel...

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Problems solved by technology

[0002] Traditional conveying cylinders are mostly directly plated with a high-hardness wear-resistant chromium layer on the surface of the cylinder body. The chromium plating process is simple, the initial working temperature is low, and the process control is convenient. However, due to the high hardness of the chromium layer, large internal stress, and ductility It is very small, forming a large contrast with the substrate material with lower hardness and better ductility, and during use, due to the release of the internal stress of the coating, the original micro-cracks in the local coating expand and deepen to reach the substrate, resulting in concrete grout It penetrates into the cylinder body and forms a corrosion cell with the coating, and as the corrosion point increases, the bonding force between the coating and the metal of the cylinder body becomes worse, and even causes local chromium layer peeling off, shortening the service life of the delivery cylinder

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