JPS6039503B2 - How to set rolling roll grinding amount using X-rays - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the amount of grinding of a roll and a method of setting a reasonable amount of grinding to prevent fatigue failure when determining the amount of grinding of a roll.

The present invention relates to a workpiece for hot and cold rolling.

However, for convenience of explanation, we will explain the grinding of a work roll for cold rolling. The purpose of grinding a stretched work roll is to remove wear, dents, cracks, and fatigue layers on the roll surface that occur during use, and to regenerate a new surface shape and properties so that the roll can be used repeatedly.

In this case, if the amount of grinding is more than necessary, the unit consumption of the roll will increase, and the manufacturing cost of the rolled product will increase.

Therefore, it is desirable to minimize the amount of grinding. Conventionally, for cold-rolled work rolls, the amount of grinding has been determined by adding a certain empirically determined amount to the amount required to eliminate the curls and cracks on the roll surface.

With this method, accidents such as roll breakage during rolling and peeling of the quenched layer due to the cracks remaining on the surface of the rolled product can be prevented, but the additional amount determined empirically above does not exceed the amount actually required. There is a tendency for the grinding speed to be set higher than that, which has the disadvantage that the amount of grinding is larger than necessary and the roll consumption rate is increased. In order to reduce the above-mentioned addition amount, the present inventor has already proposed the Tokuiso Sho No. 4811/963 (
Tokusekki No. 49-89281).

The gist of the invention is that an S-N curve is determined in advance for each material and heat treatment condition of the rolling roll, and the current degree of fatigue of the roll is estimated from the S-N curve and rolling results such as rolling pressure and rolling schedule. The remaining fatigue after the previous grinding is added to this, and the required amount of grinding is determined for each round based on the current cumulative fatigue level. The present inventor has further conducted research on actually measuring the fatigue degree of rolls using X-ray half-maximum (half the peak height in the X-ray diffraction curve), and as a result, it has been found that We have invented a grinding amount setting method that can prevent roll breakage accidents and excessive grinding.

The gist of the present invention is as follows: a. A relationship curve between the depth from the surface and the half value obtained in advance for each roll condition such as the material of the roll before rolling and heat treatment conditions; b. Roll conditions, rolling pressure, and rolling. Relationship curve between rolling roll contact deflection and surface half-value-to-average ratio and critical half-value-to-average ratio determined for each combination of rolling conditions such as oil type; c Depth from the roll surface after rolling and half-value to average ratio; The relationship curve between ;d and the x half price cloth ratio of the roll surface after rolling was actually measured, and this measured value and ;e
The next rolling schedule and ; are input into the computer, and the computer calculates and determines the required grinding amount so that the half-value cloth ratio on the roll surface does not reach the limit half-value cloth ratio at the end of the next rolling. It is in the method of setting the grinding amount of a rolling roll using a wire. However, during half value: 1 of the peak height in the X-ray diffraction curve
/2 refers to the inside.

Half-price ratio: Calculated as b/B, which is the ratio of half-price B when the roll is not used and half-price b after the roll is used.

Now, in the method of the present invention, a relationship curve between the depth from the surface and the half-value ratio is obtained in advance for each roll condition such as the material of the rolling roll and the heat treatment conditions. This is to use it as a standard for calculating b/B. Here, B is the half price at the time of use, and b is the half price after the start of use. Note that the half price value varies depending on the material of the rolling roll and the heat treatment conditions. Also, in advance,
For each combination of rolling conditions such as roll conditions, rolling pressure, and type of rolling oil, find the relationship curve between the number of roll contacts and the surface half-value-to-average ratio, and the relationship curve between the depth from the roll surface after rolling and the half-value-to-average ratio. The reason for this is to estimate the decrease in the half-value ratio of the roll surface due to the next rolling when determining the next grinding amount. Further, the reason why the critical half-value-to-value ratio is determined is to determine the usage limit of the roll. In addition, in order to prevent rolling roll accidents, it is said that cracks should not occur on the roll surface, and taking this into consideration, the critical half-value-to-weight ratio is the surface of the rolling roll fatigue test. It is best to set a certain margin for the half-value-to-value ratio at which cracking due to fatigue occurs.

Embodiments of the present invention will be described below with reference to the drawings.

In this example, the work rolls of a cold quadruple rolling mill were tested.

The roll material is a forged and hardened roll containing chromium and molybdenum. Roll dimensions are diameter 66 m, body length 2.1
There are 8 enemies. First, while removing the roll surface layer by electrolytic polishing at several force points on the body of the roll, a relationship curve between depth from the surface and mid-half value was determined. Depth from surface is 0-15
I made it to the side. An X-ray stress measurement device was used for the measurement during half value, and the measurement method followed the X-ray stress measurement method standards of the Japan Society of Materials Science. An example of the measurement is shown in FIG. Next, we conducted a roll transfer test.

The rolling pressure was varied in the range of maximum contact pressure Pm = 80 to 140 k9/min, the number of roll contacts was varied in the range N = 1 to 1 pi, and the rolling oil was used as emulsion oil, an example of which is shown in Fig. 3. A relationship curve between the number of roll contacts and the surface half-value-to-average ratio was determined. Also, as the number of roll contacts increases,
The roll surface was observed, and from the occurrence of cracks due to fatigue, the critical half-value ratio (b'B) was determined as shown in Figure 3.
I found c. In addition, during this transfer test, we determined the relationship curve between the depth from the roll surface and the half value, and found that it was independent of the number of roll contacts and could be expressed by a curve as shown in FIG. 4 as an example.

The above relationship curve is stored in the computer, and from then on, according to the procedure shown in Figure 1, the number of rolled steel plates per round is approximately 200.
The investigation was conducted for 0 tons and 50 rolls.

In other words, first, after rolling, the surface half-value ratio is actually measured, and this is input into the computer along with the next rolling schedule, and the minimum grinding amount is determined so that the half-value ratio of the roll surface after the next rolling does not reach the limit half-value ratio. The calculations were made and printed on a typewriter installed at the roll grinding shop. This calculation procedure will be explained with reference to FIG.

Now, when the half-value ratio of the roll surface after rolling is , the relationship curve between the depth from the roll surface and the half-value ratio is calculated according to the example shown in FIG. 4, as shown in large green in the figure.

If the amount of grinding is the depth of the mouth, then the half-value-to-medium ratio decrease at the next rolling will be the same as the mouth'→Ha' (mouth→Ha, mouth''→Ha'' are also the same, but this is shown in the next rolling schedule and Fig. 3). (calculated from the illustrated curve), the half-value-to-value ratio of the roll surface after the next rolling becomes C', which is lower than the limit half-value-to-value ratio (b'B)c. If the amount of grinding is ``,'' then the half-value-to-average ratio of the roll surface after the next rolling will be ``(b/B),'' which does not reach c.
Therefore, as in mouth → C, the depth at the mouth (or C) when C matches (b/B)c becomes the required minimum grinding amount. Roll grinding was performed so as not to fall below this minimum grinding amount, and the rolls were used for rolling. After rolling, the roll surface half value was actually measured, and the same process was repeated thereafter.
The number of rolling tons of steel plate per roll is approximately 100.0.
The experiment ended when the weight reached 0.00 tons. Table 1 shows the effects of the above embodiments.

The amount of grinding of a rolling roll by the method of the present invention is significantly reduced compared to conventional methods.

In addition, the method of the present invention does not require input of rolling results or cumulative calculation of fatigue degree, and can be easily calculated using a computer, compared to the method of the invention of Japanese Patent Application No. 1963/1983. Furthermore, since the grinding amount is set by setting the grinding amount by setting the grinding amount during the half price of the neck, the reliability of the grinding amount setting is excellent.
As shown in the table, despite the reduction in the amount of grinding per 1000 tons of rolling, the frequency of peeling accidents of the hardened layer, which is conventionally said to occur more often when the amount of grinding becomes smaller, is almost the same. Table 1

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a roll grinding amount setting method according to the present invention. FIG. 2 is a graph showing a relationship curve between depth from the roll surface and mid-half value. FIG. 3 is a graph showing a relationship curve between the number of roll contacts and the surface half-value-to-average ratio. FIG. 4 is a graph showing the relationship between the depth from the roll surface after rolling and the half-value-to-value ratio. FIG. 5 is a graph showing a method for calculating the minimum grinding amount. Figure 2 Figure 3 Figure 1 Figure 4 Figure 5

Claims (1)

[Scope of Claims] 1 a. A relationship curve between depth from the surface and half width determined in advance for each roll condition such as the material of the roll before rolling and heat treatment conditions; b. The relationship curve between the number of contacts of the roll and the surface half-width ratio and the critical half-width ratio obtained for each combination of rolling conditions such as type; c The depth from the roll surface after rolling and the half-width ratio Measure the relationship curve and the X-ray half value width ratio of the roll surface after rolling, input this actual value and ;e next rolling schedule into the computer, and calculate the half value width ratio on the roll surface at the end of the next rolling. X characterized in that the required grinding amount is calculated and determined by a computer so as not to reach the limit half width ratio.
How to set the grinding amount of a rolling roll using a line. However, half-value width: refers to the width at 1/2 of the peak height in an X-ray diffraction curve. Half width ratio: Calculated as b/B, which is the ratio between the half width B when the roll is not used and the half width b after the roll is used.