JPS6227131B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for setting a roll profile for strip threading arranged in a continuous annealing furnace. Recently, continuous annealing equipment has been developed and is being used in order to efficiently perform annealing treatment for cold-rolled steel sheets or tin plate blanks. The main part of this continuous annealing equipment is a continuous annealing furnace divided into multiple chambers, and the annealing furnace is configured vertically to shorten the overall line length.
The strip is passed through a number of furnace rolls arranged one above the other. In a vertical continuous annealing furnace, it is very important to stably pass the strip inside the furnace. For example, if the strip is shifted in the width direction in the furnace, there is a risk that it will come into contact with other furnace interior members, and in severe cases, there is a problem that the line may be stopped. Furthermore, if heat buckling occurs in the strip in the furnace, it may lead to breakage. Therefore, it is desirable that the strip travel within the furnace along a predetermined threading line as much as possible. Normally, the factors that affect the threadability of the strip in the furnace include strip size, strip shape, annealing temperature, strip tension, roll profile, and electrical control, but the factors that can be addressed in the annealing furnace are: These include strip tension, roll profile, and electrical control. Among these, the present invention pays particular attention to the roll profile and aims to optimally define the profile of the hearth roll in the furnace. In order to improve sheet threadability, a convex crown is required for the roll profile, but the selection of this roll profile generally requires conditions that cannot be handled by an annealing furnace.
That is, strip size, strip shape, annealing temperature, etc. are taken into consideration, but these conditions vary widely and it is difficult to satisfy all of them. In the past, there were no particular standards for selecting crowns for hearth rolls, and most of them were determined based on empirical factors, so variations in conditions could cause problems such as unevenness or constriction of the strip. Therefore, there is currently a strong demand for optimization of role profiles. The present invention was made based on this background, and provides a roll profile setting method that can achieve the optimum profile for a hearth roll used in a vertical continuous annealing furnace, that is, stable strip threading. The purpose is to The circumstances leading to the completion of the present invention and the contents of the present invention will be explained below. In a heating furnace such as a continuous annealing furnace, the strip temperature ranges widely from room temperature to the soaking temperature, and the influence of the roll profile on the properties of the strip should be considered separately on the low and high temperature sides of the strip temperature. In other words, on the low temperature side (the strip temperature is thought to be approximately 500 to 600°C above room temperature, but the range is slightly different for tin plate and cold rolled steel plate, and is lower for tin plate), the same hearth roll temperature is the part where the strip contacts the plate. is low, and the part that does not touch the plate is high, causing a roll crown due to the temperature difference, and if this is not corrected, a concave crown will result and deviation will occur. Also, unlike outside the furnace, it is necessary to work with low tension, so if the strip temperature is low, it is likely to be affected by the shape of the original plate and cause misalignment. In general, narrow materials tend to shift more easily, wider materials have more restoring force due to the tapered portion, and if a suitable flat portion is provided, the shift is less likely to occur. On the other hand, on the high temperature side of the strip, the strip strength and yield point decrease due to the high strip temperature, and the strip tends to become constricted, and in order to prevent this, it is necessary to reduce the roll crown. In addition, on the high temperature side, the shape of the strip is corrected in the furnace and the temperature difference in the width direction within the same roll is reduced, making it difficult for unevenness to occur. From the above, in a heating furnace, it is ideal to change the profile every time the strip temperature rises, that is, every roll.
Selection of profiles for each book is extremely troublesome, and at the same time, rolls must be replaced periodically.
It is uneconomical to have spare parts available. Therefore, in consideration of the above points, the inventors investigated and examined the threadability by changing various roll profiles, and found that the roll profiles were divided into two groups, one on the low-temperature side and one on the high-temperature side of the strip. It turned out that there was nothing wrong with that either. The hearth roll targeted in the present invention is a narrow body type shown in FIGS. 1A and 1B, and the low temperature side may be of type A, and the high temperature side may be of either type A or B. These narrow body type rolls are composed of a tapered part 1 having slopes on both sides and a central flat part 2, and although the length of the central flat part and the slope of the tapered part are correlated in some respects, each has an effect on the threadability of the strip. make a big impact.
First, if the length of the central flat portion is not appropriate, good sheet threadability cannot be obtained even if the slope of the tapered portion is changed. This works to return the tapered part to the center when it is lopsided, and the rest works to ensure stable running in the central part.In order to run stably, the necessary central part is first determined by the size of the board. . or,
The inclination of the tapered portion is determined by the balance between the aperture and off-centeredness, but if the inclination is too steep, the aperture will be loose, and if the inclination is too loose, it will be off-centered. In the present invention, the strip temperature is divided into a low temperature side and a high temperature side, and the central flat part length is Wmin/F1.6 to 4.5 from the minimum threading width on the low temperature side, and Wmax/F1.5 to 2.7 from the maximum threading width on the high temperature side. and the slope of the taper part is l/δ100~200 on the low temperature side and l/δ on the high temperature side.
Defined as δ150-330. Wmin is the minimum width of the strip passed through the furnace, Wmax is the maximum width, and F
As shown in FIG. 1, represents the length of the central flat portion, l represents the horizontal length of the tapered portion, and δ represents the height of the tapered portion. Using the minimum plate width and maximum plate width of the threading material to define the central flat length on the low-temperature side and high-temperature side, respectively, is because it tends to be uneven on the low-temperature side compared to the high-temperature side, and the width is narrower. Since the deviation tends to be more pronounced as the material becomes wider, it is sufficient to specify the minimum plate width. On the side, it may be specified in relation to the maximum board width. In addition, regarding the slope of the taper part, the slope angle tends to be steeper on the low temperature side and on the high temperature side, but this is because, as mentioned above, deviation tends to occur on the low temperature side. The centering function is strengthened by increasing the slope of the taper part, which has the function of returning the ball to the center. On the other hand, on the high temperature side, countermeasures against throttling become important, so the slope of the tapered portion cannot be made too large. Setting Wmin/F to 1.6 to 4.5 on the low temperature side is because
If it is smaller than the lower limit or larger than the upper limit, bias will occur, and Wmax/F should be 1.5 to 1.5 on the high temperature side.
The reason why it is set to 2.7 is that if it is too small than the lower limit, it will be biased, and if it is too large than the upper limit, it will be apertured. In addition, the reason why the slope (l/δ) of the tapered part is set to 100 to 200 on the low temperature side and 150 to 330 on the high temperature side is that if the value is smaller than the lower limit of each, the material will be narrowed down.
This is because flaws are likely to occur, and if the value exceeds the upper limit, deviation will occur. Note that in the narrow body type roll to which the present invention is applied, both the central flat part and the tapered part are linear as shown in FIG. 1, but the present invention is not limited to this; It is also possible to form a roll made up of a part of. Of course, even in this case, it is necessary to specify the range of the length of the central flat portion and the slope of the tapered portion as described above. FIG. 2 shows an example in which the tapered portion is formed into an arc and the flat portion is formed into a straight line, and FIG. 3 shows an example in which the central flat portion is formed into an arc and the tapered portion is formed in a straight line. Example

[Table] The results of examining the threadability in the tests A and B above are shown in FIGS. 4 and 5, and Tables 1 and 2. Figure 4 shows the relationship between Wmin/F and threadability.
The figure is a graph showing the relationship between Wmax/F and threadability. Table 1 shows the passability of the tapered part on the low-temperature side for the type shown in A in Figure 1, and Table 2 shows the passability of the tapered part on the high-temperature side for the roll type shown in Figure 1 A and B. This shows the quality of the sheet threadability with respect to changes in the inclination angle. In addition, skewing is defined as a situation in which the rate of deceleration during threading is 10% or more at the maximum threading speed, and skewing is defined as skewing occurring at a coil ratio where the reduction is 2% or more in threaded material. The board quality was judged by the degree of deviation and drawing.

【table】

[Table] R, ○ Good, × Aperture, × × Slip defects As can be seen from the drawing and table, Wmin/F is
If Wmax/F is in the range of 1.6 to 4.5 and Wmax/F is in the range of 1.5 to 2.7, the sheet threadability is good and stable running is achieved. Also, l/δ is 100 to 200 on the low temperature side and 150 to 200 on the high temperature side.
330 has good threading properties, and if it is removed, it will become uneven,
It was observed that aperture occurred.

[Brief explanation of the drawing]

FIGS. 1A and 1B are front views showing examples of roll type shapes to which the present invention is applied, and FIGS. 2 and 3 are
The figure is a front view showing another roll type to which the present invention is applicable, Figure 4 is a graph showing the relationship between the threadability on the low temperature side and the horizontal flat length, and Figure 5 is the graph showing the relationship between the threadability on the high temperature side and the length of the horizontal flat. It is a graph showing the relationship with the horizontal flat length.

Claims (1)

[Claims] 1. When selecting the profile of a narrow body hearth roll placed in a vertical continuous annealing furnace, on the low temperature side of the stripping temperature, the length F of the roll center flat part should be 1.6 to 4.5, and the tapered part It is characterized by being configured so that the slope l/δ is 100 to 200, the length of the central flat part is F/Wmax 1.5 to 2.7 on the high temperature side, and the slope l/δ of the tapered part is 150 to 330. How to set the roll profile in a continuous annealing furnace. However, Wmin: Minimum width of the strip to be threaded Wmax: Maximum width of the strip to be threaded l: Horizontal length of the tapered part δ: Height of the tapered part 2 At least one of the central flat part and the tapered part of the roll is The setting method according to claim 1, which comprises a part of a sine curve.