TWI464273B - Production Method of Hot - dip Galvanized Steel Coil - Google Patents

Description

Production method of hot dip galvanized steel coil

The invention relates to a method for producing a steel coil, in particular to a method for producing a hot dip galvanized steel coil.

Referring to Figure 1, a conventional method for producing a hot dip galvanized steel coil includes a cold rolling step 11 and a hot dip galvanizing step 12. The cold rolling step 11 can roll out a long strip of steel strip, and then carry out a hot dip galvanizing process on the strip to produce a hot dip galvanized steel coil.

However, due to the processing conditions of hot dip galvanizing, the thickness of the coating of the hot dip galvanizing process is relatively uneven, and the thickness of the plating layer near the edge of the steel strip is generally thick, and the thickness of the coating near the center of the steel strip is thin. Therefore, the hot-dip galvanized steel coil produced by the conventional hot-dip galvanized steel coil production method has poor uniformity in thickness, and if the thickness difference is too large, it may need to be scrapped. First, it will affect the cost and quality of hot dip galvanized steel coils of steel mills. Secondly, it will not be conducive to the subsequent application of downstream manufacturers, and even affect the manufacturing cost and quality competitiveness of downstream manufacturers.

Therefore, how to improve the above-mentioned shortcomings has been an important goal of continuous efforts by those skilled in the art.

Accordingly, it is an object of the present invention to provide a method of producing a hot dip galvanized steel coil having a relatively uniform thickness.

Thus, the method for producing a hot dip galvanized steel coil of the present invention comprises a predicting step, a measuring step, and a screening galvanizing step.

The prediction step is to obtain a reference edge drop value by statistical method.

The actual measurement step is used to measure the thickness of most steel strips in the width direction to obtain an average side drop value of each steel strip.

The screening galvanizing step is used to screen a steel strip having a minimum average edge drop value less than the reference edge drop value for hot dip galvanizing to produce a majority of hot dip galvanized steel coils.

The utility model has the advantages that: the steel strip is screened by the reference edge drop value obtained by the predicting step, and the steel strip with the smallest average edge drop value smaller than the reference side drop value is hot dip galvanized due to hot dip Zinc plating will form a thicker galvanized layer on the edge of the steel strip. Therefore, it is possible to produce a hot-dip galvanized steel coil with a smaller uniform thickness and a thinner edge.

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments.

Referring to FIG. 2, a preferred embodiment of a method for producing a hot dip galvanized steel coil according to the present invention comprises a predicting step, a measuring step, and a screening galvanizing step.

First, a reference edge reduction value is obtained statistically by the prediction step. In the preferred embodiment, statistical analysis is performed on the data of the previously produced steel strip and the hot dip galvanized steel coil to obtain the reference edge drop value.

In the preferred embodiment, the reference edge drop value and the thickness of the galvanized layer of the hot dip galvanized steel coil conform to the formula: X = -αW. Where X is the reference edge drop value, W is the thickness of the galvanized layer of the hot dip galvanized steel coil, and α is the edge plating thickening factor. In the preferred embodiment, W is the expected galvanized layer thickness, edge plating The value of the thickening factor α is a numerical value obtained by statistically anomalous steel coils, and the manner of statistics is known to those of ordinary skill in the art, and therefore will not be described again. In the present experimental example, α = 0.033, X = -6, and W = 180.

The thickness of the majority of the steel strips in the width direction is measured by the actual measurement step to obtain an average side drop value of each steel strip. In particular, the so-called average edge drop value is a thickness measurement value obtained at a position where the steel strip extends linearly in the width direction.

In the actual measuring step, the average thickness of an edge of each steel strip on the edge section and a central average thickness of the central section are obtained by actual measurement, and the average edge value is the average thickness of the edge. The difference from the central average thickness, in particular, there are many methods for actually measuring the thickness, and the method of measuring the thickness is not the main technical feature of the present case, and therefore will not be described.

It is worth mentioning that the edge section refers to a section of 5 mm to 10 mm at the edge of each steel strip, and the central section refers to a section of 20 mm to 25 mm at the edge of each steel strip, of course, the edge section or The sampling frequency of the central section depends on the accuracy required. If higher accuracy is required, the sampling frequency must be increased. Further, in the preferred embodiment, the steel strip is a steel strip produced by a cold rolling process and produced by a cold rolling process.

Then, the screening galvanizing step is performed, and the average edge drop value obtained in the actual measuring step is compared with the reference edge falling value of the prediction step, and then the steel strip with the smallest average edge falling value smaller than the reference edge falling value is selected, and finally The hot dip galvanizing process is then performed on the steel strip to produce a majority of hot dip galvanized steel coils.

Referring to Figures 3 and 4, TD _I is the average edge drop (AVG THK deviation) from the two points 20 mm and 25 mm from the edge of the strip; TD _E is the average edge drop of the points 5 mm and 10 mm from the edge of the strip. ETD (Edge THK difference) is the degree of edge drop; ETD = TD _{E -} TD _I .

As can be seen from Fig. 3, TD _I = (DS20 + DS25) / 2 = (-2.8 - 3.2) / 2 = -3.0 μm, TD _E = (DS05 + DS10) / 2 = (-6.7 - 6.7) / 2 = - 6.7 μm, ETD=TD _E -TD _I =-6.7+3.0=-3.7 μm (<0), the minimum average side drop of the steel strip is -6.7 less than the reference edge drop value of -6, and as can be seen from FIG. TD _I =(DS20+DS25)/2=(-2.4-2.2)/2=-2.3μm, TD _E =(DS05+DS10)/2=(-0.3-1.9)/2=-1.1μm, ETD= TD _E -TD _I =-1.1+2.3=+1.2μm (>0), the minimum average edge drop of the steel strip is -2.3 greater than the reference edge drop value of -6, after actual hot dip galvanizing process, The steel strip of Fig. 3 does not bulge after the actual hot dip galvanizing process, and the steel strip of Fig. 4 does bulge after the actual hot dip galvanizing process.

It should be specially noted here that the rolling delay is generally smaller than the thickness of the center of the steel strip. Therefore, the average edge drop from the edge of the strip is generally smaller than the average edge drop in the center of the strip, so the minimum The average edge drop value will occur in the edge section of the steel strip, while the edge drop degree ETD is more negative as shown in Figure 3. The ETD of the steel strip of Figure 4 is a positive number, which means that the edge of the strip has been bulged, which is not suitable. Subsequent hot dip galvanizing process.

In summary, the method for producing the hot dip galvanized steel coil of the present invention is to screen the steel strip by the reference edge drop value obtained by the predicting step, and the minimum average side drop value is less than the reference side drop value. The steel strip is hot dip galvanized. Since hot dip galvanizing forms a thick galvanized layer on the edge of the strip, it is screened out. A steel strip having a thinner edge can produce a hot-dip galvanized steel coil having a more uniform thickness, so that the object of the present invention can be achieved.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

21‧‧‧ Forecasting steps

22‧‧‧Measurement steps

23‧‧‧ Screening galvanizing steps

1 is a flow chart showing a method for producing a hot dip galvanized steel coil; FIG. 2 is a flow chart showing a preferred embodiment of the method for producing a hot dip galvanized steel coil according to the present invention; It is a data graph showing the results of the normal stripless steel strip thickness measurement; and Fig. 4 is a data graph showing the thickness measurement results of the edge bulging steel strip.

twenty one. . . Prediction step

twenty two. . . Measured step

twenty three. . . Screening galvanizing steps

Claims (5)

A method for producing a hot dip galvanized steel coil, comprising: a predicting step of obtaining a reference edge drop value by a statistical method, wherein a reference edge drop value of the predicting step and a galvanizing of the hot dip galvanized steel coil The layer thickness conforms to the following formula: X=-αW, where X is the reference edge drop value, W is the galvanized layer thickness of the hot dip galvanized steel coil, α is the edge plating thickening factor; a measured step measures most steel a thickness in the width direction to obtain an average edge drop value of each steel strip; and a screening galvanizing step to screen a steel strip having a minimum average edge drop value less than the reference edge drop value for hot dip galvanizing process to produce Most hot dip galvanized steel coils. The method for producing a hot dip galvanized steel coil according to claim 1, wherein in the measuring step, measuring is performed to obtain an average thickness of an edge of each steel strip located on the edge portion and located at the center A central average thickness of the segment, the average edge drop being the difference between the average thickness of the edge and the average thickness of the center. The method for producing a hot-dip galvanized steel coil according to the second aspect of the patent application, wherein in the actual measuring step, the edge section refers to a section located at an edge of each steel strip of 5 mm to 10 mm, and the central section is Refers to the section 20mm~25mm at the edge of each steel strip. The method for producing a hot dip galvanized steel coil according to any one of claims 1 to 3, wherein in the predicting step, the previously produced steel strip and hot dip galvanized steel coil are produced. Statistical analysis to obtain The reference edge is down. The method for producing a hot dip galvanized steel coil according to any one of claims 1 to 3, wherein in the actual measuring step, the steel strip is produced by a cold rolling process.