KR20010011459A - Method for grinding the surface of working roll by on-line roll grinder - Google Patents

Abstract

PURPOSE: A grinding method is provided to precisely maintain roll profile through eliminating step difference between whole plate unit and a non-whole plate unit of an operation roll. CONSTITUTION: A wheel(122) is moved at different speeds in whole plate unit and non-whole plate unit of an operation roll(100) to grind step of the non-whole plate unit. Movement of the wheel is stopped at edges of the roll for grinding. Separate point locations of the roll are calculated. After rolling a piece of material, abrasion amounts at each separate location are calculated. Accumulated abrasion profile is calculated. After calculating grinded amount by online roll grinder(120), the result is accumulated to the abrasion profile. Requirement of grind is decided to calculate grinded amounts at each separate section. Moving speeds of the wheel for each section are calculated. Movement of wheel and grind are performed according to moving speeds of the wheel.

Description

Work roll surface grinding method by online roll grinder {METHOD FOR GRINDING THE SURFACE OF WORKING ROLL BY ON-LINE ROLL GRINDER}

The present invention relates to a method for grinding the surface of a work roll by an on-line roll grinder, and more particularly, to effectively remove the step difference between the plate part and the non-plate part of the work roll to maintain the roll profile at all times and accurately. The present invention relates to a method for grinding work roll surfaces by an on-line roll grinder that is improved to improve work quality and prevent equipment accidents during rolling.

In general, in the rolling mill, the roll 100 and the rolled material (strip, sheet material, etc.) 110 are damaged when the raw material is rolled, causing cracks on the roll, cracks due to heat, and rough surface. In addition, as the rolling progresses, the plate part 100a and the non-plate part 100b of the roll 100 generate a large step as shown in FIG. 2 as time passes, and in this case, the roll is usually replaced. Or gradually roll a narrow material.

That is, in order to prevent the rolling failure of the rolled material 110 due to the roll wear profile in general, roll unit rolling is performed, which is carried out by the initial material having a wide plate width, and gradually rolling the plate with a narrow plate width. do. Therefore, when rolling from the wide member to the narrow member, the step portion of the roll as shown in FIG. 2C is generated according to the roll wear amount of the wide member and the narrow member.

Otherwise, if the rolling is performed by reversing the size from the narrow width of the rolled material 110 to the wide width of the rolled material 110, both edges of the material are excessively rolled to generate stretching. It can be the cause of poor quality of rolling materials and rolling accidents.

As described above, the height of the step to be removed from the roll 100 in which the step is formed becomes e of FIG. 2, and when the lengths of c, d and g are removed, the roll profile during the actual rolling is obtained from the initial profile. Similarly, rolling is performed in a rolling unit independent of the width of the material.

In order to maintain the roll profile as described above, a rolling operation was conventionally performed using an on-line roll grinder 120 as shown in FIG. 1.

At this time, as a method of removing the roll step portion, when rolling the rolled material per buried material, the roll abrasion amount due to the roll contact with the rolled material 110 is calculated and the step size as shown in e in FIG. Save the profile on a process computer, for example. And if the size of the e reaches a predetermined amount or more and it is determined that there is difficulty in reversing from the smaller side to the wider plate width, it is removed through the roll grinder 120 during rolling or between rolling and rolling.

The apparatus includes a front and rear drive unit 124 for contacting the rotary grindstone 122 along the surface of the roll 100, forward and backward driving, and a rotation means 126 for rotating the grindstone 122. The grindstone 122 is ground with the reciprocating time of a fixed period in the longitudinal direction of the roll 100.

However, this method did not effectively remove the step e portion formed in the plate part 100a and the non-plate part 100b of the roll 100, and the step e part still remained.

The reason is that the grinding speed and the grinding amount of the roll plate part 100a and the non-plate part 100b are equally applied, so that the polishing state of the step e portion is poor.

That is, when grinding the grindstone 122 in a roll length direction with a constant reciprocating time, as shown by the dotted line in Figure 6, the removal of the stepped portion is insufficient.

The present invention is to solve the conventional problems as described above, the purpose is to effectively eliminate the step difference between the plate and the non-sink portion of the work roll to maintain the roll profile (correctly) always accurate to improve the rolling quality The purpose is to provide a work roll surface grinding method by an on-line roll grinder which is improved to prevent equipment accidents during rolling.

1 is a block diagram of an online roll grinder to which the present invention is applied;

Fig. 2 is a block diagram showing a quarter section of the roll showing the step between the plate part and the non-plate part of the roll due to abrasion by the strip during rolling;

3 is an enlarged detailed view showing a state of a roll surface;

Figure 4 is a flow chart showing in order the work roll surface grinding method of the present invention;

5 is a cross-sectional view of the roll after grinding by the work roll surface grinding method according to the present invention;

6 is a cross-sectional view of the roll after grinding by the work roll surface grinding method according to the prior art;

7 a), b) and c) are graphs showing the results after grinding by the grinding method of the present invention and the conventional grinding method.

Explanation of symbols on the main parts of the drawings

100 ..... work roll 100a .....

100b .... Non-mailing section 110 ..... Rolled material

120 ..... Online Roll Grinder

122 ...

In order to achieve the above object, the present invention provides a work roll surface grinding method using an on-line roll grinder for grinding the roll surface by moving the grinding wheel in the longitudinal direction of the roll based on the grinding target amount by the amount of wear calculated in advance. In

It is to provide a method for grinding the surface of the work roll by the on-line roll grinder, characterized by grinding the stepped portion of the non-plate part by changing the grindstone moving speed of the plate and the non-plate part of the work roll to be processed.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

The grinding method according to the present invention is to effectively grind the stepped portion of the non-plate part 100b by varying the moving speed of the plate part 100a of the work roll to be processed and the grindstone 122 of the non-plate part 100b.

As shown in order in FIG. 4, first, in step 210, the rolled portions are divided by predetermined intervals to calculate the split point position in each division.

Then, a step 220 of calculating the amount of wear at each divided section position of the work roll 100 after the rolling of the rolled material 110 is performed, which is based on the following equations for the amount of wear and the roll profile due to the wear at every rolling. Predict using Equation 1.

Calculate the wear profile at the position of each divided section of the work roll 100 after rolling of one rolled material (coil, sheet, etc.) 110,

W (j) = K * (P (j) / S) ^α * (Fs) ^β * Dw * N

Where P (j) is the rolling load at the position j in the roll eastern direction,

S: Plate Width * Projection Contact Length * Roll Hardness

N: Roll rotation speed, L: Rolled material length (W (1), W (2), W (3) .... W (j))

Dw: Work roll diameter Fs: Friction distance (rolling down rate / (1-rolling down rate) * projection contact length)

K, α, β: Coefficient of adjustment, j: Random split point of roll

Equation (1) divides each point at regular intervals in the longitudinal direction of the work roll 100 using conditions such as rolling pressure, length of the rolled material 110, roll diameter, and the like. The amount of wear per each rolling of 110 is calculated. In the above, the position where the roll 100 and the rolled material 110 are in contact with each other is determined by receiving the information of the target plate width from the upper calculator and calculating the rolling load in each division section on the assumption that the roll 100 passes through the center portion. Find the projection contact length.

The projection contact length refers to the length of contact with the rolled material 110 along the circular outer circumferential surface of the roll 100 when the rolled material 110 is rolled in contact with the roll 100.

In addition, at the edge of the rolled material 110, the load is locally applied to the roll 100 due to the temperature decrease, thereby increasing the amount of roll wear, thereby compensating for the calculation of the amount of wear when calculating the load. In the part where the roll 100 and the to-be-rolled material 110 are not in contact with each other, the load is '0' so that there is no change in the amount of wear, and the amount of wear is regarded as '+'. To increase.

At the end of the rolling of each rolled material, the calculation of adding the wear amount calculated in each section to the previous wear profile is performed to perform the cumulative wear profile of the work roll 100 as in step 230.

Calculation of cumulative wear profile Y (j) = Yb (j) + W (j),

Where Yb (j) is the cumulative wear profile up to the previous time.

In order to eliminate the calculated deviation between the predicted and calculated cumulative wear profile and the actual, the steel grade, the material to be rolled (110) thickness, width, rolling pressure, roll (100) material, etc. are classified according to the conditions, and the roll profile after actual work The measurement accuracy is improved by correcting the wear correction coefficient (k is usually 0.8 to 1.2).

From the roll profile data, the size of the step and the size of the step to be removed by the on-line roll grinder 120 can be known.

Next, the grinding process by the on-line roll 100 grinder 120 will be described.

First, in step 240, as in the roll 100 wear, the amount of grinding by the roll online grinder 120 is calculated according to Equation 1a, and the cumulative calculation is performed on the roll wear profile.

Grinding capacity = grinding coefficient * grinding pressure * (roll speed + grinding wheel rotation speed)

Grinding time (i) = (Required grinding amount * 60π * Roll diameter * Grinding distance (i)) / (grinding capacity * 10000), (i = generated by rolling material during rolling such as c, d, g, etc. Step width section)

Grinding amount (i) = (grinding capacity * 10000 * actual grinding time) / (60π * roll diameter * grindstone movement distance (i)), (i = caused by the rolled material during rolling such as c, d, g, etc. Step width section)

In the on-line roll grinder 120, grinding is performed when the size of the step exceeds a predetermined amount, that is, the grinding target amount is calculated by calculating from the cumulative wear profile, and the next step is larger than the allowable wear level. Grind at

Therefore, this step 250 is a step of determining whether the grinding is necessary, at this time, the amount of wear is allowed because the grinding is performed every time the coil is rolled, so it is not necessary to scrape off the roll 100, the number of grinding, roll profile is rolled material (110) Review and determine the impact. In this case, the allowable wear amount is obtained by using Equation 4 below.

Allowable wear (i) = (k1 * grinding capacity * actual grinding time) / (60π * Dw * grindstone travel distance (i) * As), (i = c, d, g, etc. Caused by step width)

Where K1: unit conversion factor (unit conversion factor for converting cc unit to mm)

Dw: diameter of working roll 100, As: step grinding rate (preset as grinding ratio for step generation amount, ie, if you want to grind 80μm out of 100μm, As is 0.8)

Here 60 * π is to convert the grinding capacity per working roll diameter per second because the unit of grinding capacity is cc / min.

At this time, the grinding target portion is inversely proportional to the moving speed of the grindstone, that is, the more the target to be ground, the slower the speed is moved to increase the amount of grinding.

When it is determined whether grinding is necessary in this way, a step 260 of calculating the amount of grinding in the divided section of each work roll is made, which uses Equation 3a, and then grinds in each section during grinding. A step 270 of calculating the moving speed is made.

In the case of the edge portion of the rolled portion, the grinding amount is relatively lowered by stopping before reaching the edge portion in consideration of the inertia of the grindstone 122 and changing the direction. However, the ungrinded roll moving part edge portion causes the roll 100 accident due to stress concentration at the edge portion generated by the upper and lower working rolls 100 contacting and rotating when the thickness of the rolled material 110 is thin. do. Therefore, in this part, the grindstone 122 is stopped for a predetermined time in order to increase the amount of grinding, thereby increasing the amount of grinding, and effectively removing the stepped portion, thereby preventing accidents such as cutting of the roll 100 in advance.

For example, when the grinding target is enlarged in FIG. 2, parts A and B of FIG. 3 are enlarged, and since the grinding target amounts are different from each other, grinding is performed by increasing the moving speed of the grindstone 122 in the A section, and in the B section. Since the grinding should be more than the A portion, the grinding wheel 122 is moved slowly to perform a large amount of grinding. In addition, the distance of g of FIG. 3 stops for a predetermined time to increase the amount of grinding since grinding is not performed in a timely manner to the position where the grindstone 122 changes the moving direction. When the grindstone 122 is moved along the surface of the roll 100, the calculation of the grinding ability, the grinding time, and the grinding amount of the on-line roll 100 grinder 120 is performed in the following equations (2), (3) and (3a). Is determined by. The moving speeds of the grindstones 122 of parts c and d of FIG. 3 are calculated by Equation 5 below.

Grinding Wheel (122) Movement Speed (i) = Grinding Time (i) / Grinding Wheel (122) Movement Distance (i), (i = c, d)

After the above steps, the step 280 of moving and grinding the grindstone 122 is made in accordance with the movement speed of the grindstone 122 for each section, which is inertial when the grindstone 122 moves along the rolled portion. In order to avoid leaving the rolled portion, the movement is stopped at the position of the distance g of FIG. 3 from the edge portion of the roll, and moved in the opposite direction. At this time, in order to increase the amount of grinding, the stop time is calculated by using the equation (3) inversely calculating the remaining grinding target portion from the ungrinded profile at the existing actual roll moving edge portion.

In addition, in order to test this, the grinding ability is performed by performing about 5 to 10 minutes of grinding in the actual short section. Then, the roll profile is measured directly and the stop time is corrected by comparing the theoretical calculation with the actual grinding amount. When moving from the roll center part to the edge part at the time of grinding, the moving speed of the grindstone 122 is determined with the goal of grinding the half of the grinding target amount, and when moving back to the center, the moving speed is determined to perform the remaining grinding. Then, the grinding wheel 120 drives the grinding wheel 122 driving motor by giving a command necessary for grinding, and grinding the grinding wheel 122 at a moving speed from the center to the edge and the edge to the center according to the roll surface. Do it.

After grinding through the on-line roll grinder 120, the process control calculator sends the grindstone 122 moving speed to the upper calculator, the upper calculator receives the grindstone 122 moving speed feedback, and the wear calculation amount using the equation (step size) ) And the cumulative wear profile. Repeating this process, as shown by the dotted line in Figure 5, it is possible to maintain the initial profile.

Hereinafter, the present invention will be described in more detail with reference to Examples.

(Example)

On-line roll grinder was rolled using 32 sheets of ordinary carbon steel sheets 2.5mm thick and 995mm wide, 45 sheets of ordinary carbon steel sheets 2.7mm thick and 1173mm wide, and 37 sheets of plain carbon steel sheets 3.2mm thick and 1280mm wide. The roll profile when 120) was not used was measured and shown in FIG. 7C). 43 sheets of general carbon steel sheets 2.1 mm thick and 895 mm wide, 40 sheets of 2.4 mm thick and 1151 mm wide carbon sheets, and 34 sheets of plain carbon steel sheets 3.1 mm thick and 1250 mm wide were rolled. The roll profile in the case of using the polishing method by the on-line roll grinder 120 was measured and shown in FIG. 7B). In addition, 47 sheets of ordinary carbon steel sheets 2.1mm thick and 880mm wide, 27 sheets of ordinary carbon steel sheets 2.3mm thick and 1145mm wide, 15 sheets of regular carbon steel sheets 3.1mm thick and 1250mm wide, 3.4mm thick and 1270mm wide The roll profiles after rolling using 39 sheets of ordinary carbon steel sheet and ground by the grinding method according to the present invention are shown in Fig. 7A).

As shown in FIG. 7C), when the on-line roll grinder 120 is not used, the step due to the fluctuation remains.

In the case of the conventional grinding method, that is, when grinding the non-plate part at a constant grindstone 122 moving speed, the size of the step is reduced, but the edge part remains large, and the inclined part c as shown in FIG. Therefore, the grinding was difficult to remove the stepped portion, the grinding portion is small for the g portion of Figure 3 where the change of direction in the eastern edge portion of the roll (100) local protrusions remain intact always risk of accidental loss of the roll (100) This was to be.

However, as a result of applying the grinding method of the present invention, the size of the step and the edge portion were well ground, and in the c portion, the inclined portion of FIG. 2, the grinding step 122 was changed by varying the moving speed of the grindstone 122 according to the size of the grinding target. The removal of the parts became easy.

In addition, when the moving direction of the grindstone 122 is changed at the eastern edge portion of the roll 100, a large amount was ground by stopping the grinding for a predetermined time, and thus, when the upper and lower work rolls 100 are in contact with each other, the grinding force is more than conventional. The surface was in contact to prevent localized stress, reducing the risk of the roll 100 breakage accident.

In this case, the calculation of the stop time was derived from the above equation and the actual grinding test results, and a stop time of 0.7 to 1.0 second was the most suitable.

As described above, according to the present invention, the grinding stone 122 is moved along the surface of the roll 100, and the grinding speed is varied according to the grinding target amount during grinding, and the grinding effect is excellent. Through this, rolling is performed regardless of the increase in the number of rolls per unit and reduction or increase in width in one unit after one roll 100 replacement, thereby reducing heat source units, reducing process load, and improving plate quality. It is.

Claims (3)

The work roll surface grinding method by the on-line roll grinder 120 which grinds the surface of the roll 100 by moving the grindstone 122 in the longitudinal direction of the roll 100 based on the grinding target amount by the amount of abrasion calculated in advance. In Work by an on-line roll grinder, characterized by grinding the stepped portion of the non-plate part 100b by varying the moving speed of the plate part 100a of the work roll 100 to be processed and the grindstone 122 of the non-plate part 100b. Roll surface grinding method. The method of claim 1, wherein both edges of the work roll (100) are ground by stopping movement of the grindstone (122). The operation of claim 1, wherein the step of grinding the stepped portion of the non-plate part 100b is Calculating an angle division point position of the work roll 100 (210); Calculating the amount of wear at each of the divided section positions after the rolling of the rolled material of the one piece 100; Calculating a cumulative wear profile in each division section (230); Calculating a grinding amount by the roll online grinder 120 and accumulating it on the roll 100 wear profile (240); Determining 250 whether grinding is required; Calculating a grinding amount in the divided section of each work roll 100 (260); Calculating grinding speed (122) of the movement speed in each section during grinding (270); Step (280) for moving and grinding the grindstone (122) in accordance with the movement speed of the grindstone (122) for each section; the work roll surface grinding method by the on-line roll grinder comprising a.