Zinc-plated steel sheet and method for preparation thereof, and method for manufacturing formed article by press working

Abstract

The method for manufacturing galvanized steel sheet has a step of adjusting the surface texture thereof by blasting solid particles against the surface thereof. The surface texture is defined by at least one parameter selected from the group of parameters consisting of mean roughness Ra on the surface of steel sheet, peak count PPI on the surface of steel sheet, and filtered centerline waviness Wca on the surface of steel sheet. The galvanized steel sheet has a surface in dimple-pattern texture.

Description

technical field [0001] The present invention relates to a galvanized steel sheet, a method for manufacturing it, and a method for manufacturing a press-formed product. Background technique [0002] The demand for thin steel sheets with excellent antirust performance for automobiles, home appliances, and building materials is increasing. The surface of the galvanized steel sheet used for stamping needs to have appropriate micro-concave-convex roughness. This is because the microscopic unevenness on the surface of the steel plate can improve the performance of storing lubricating oil between the stamping dies, reduce the sliding resistance, and at the same time have the effect of preventing die sticking. [0003] The average roughness Ra specified in JISB0601 is generally used as an index indicating the microscopic concave-convex shape of the steel plate surface. For galvanized steel sheets used for stamping, generally the value of the average roughness Ra should be adjusted...

AI Technical Summary

Problems solved by technology

However, when the above-mentioned various roll surface processing methods are used to increase the surface roughness of the roll, the peak number PPI will be reduced, and it is difficult to increase both the average roughness Ra and the peak number PPI.

[0021] When such a galvanized steel sheet is used for press forming, the performance of retaining lubricating oil between the press dies is insufficient, the sliding resistance becomes large, and there is a problem that the steel plate on the punch surface or the steel plate near the rib of the die is easily damaged.

[0022] The second problem is that due to the biting of the roll during leveling, the contact pressure between the roll and the steel plate is very large, and the microscopic unevenness (surface roughness) on the surface of the roll will change with time due to wear, and the microscopic unevenness copied to the surface of the steel plate It is difficult to maintain a fixed appearance

In addition, it is not only a problem of wear and tear. The concave part of the microscopic unevenness on the surface of the roll will adhere to the zinc powder peeled off from the steel plate. Due to the so-called clogging, the surface roughness of the roll will decrease, which will also cause the microscopic unevenness of the surface of the galvanized steel plate manufactured. produce changes over time

[0026] The third problem is that it is difficult to obtain the same level of surface roughness when the steel type of the galvanized steel sheet to be processed changes with the existing method of manufacturing galvanized steel sheets, and the hardness of the base material is different.

At this time from Figure 36 From the results shown, it can be seen that galvanized steel sheets meeting such conditions can be produced for soft materials, but the desired purpose cannot be achieved for hard materials even if the same roll is used

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