JPH0457404B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a method for grinding work rolls in a rolling mill, and in particular, a method incorporating a pair of work rolls having a tapered portion at one end and reciprocating in the axial direction. The present invention relates to a method for grinding work rolls in a work roll shift rolling mill.

BACKGROUND ART At present, a four-high rolling mill having the configuration shown in FIG. 4A is the mainstream finishing rolling mill in a hot rolling facility, for example. This four-high rolling line has a structure in which a pair of substantially cylindrical work rolls 1 and 2 are arranged vertically in parallel, and back-up rolls 3 and 4 are arranged behind them (i.e., on the upper or lower side). The rolling force on the rolled material 5 is assisted by the back-up rolls 3, 4, and also performs a bending action via the back-up rolls 3, 4. When rolling is performed using this type of rolling mill, the rolled material 5
The profile becomes convex as a whole, forming a crown, as shown in Figure B. Since the crown has a negative effect on the shape accuracy of the final product and the subsequent cold rolling process, it is basically preferable to correct the crown as much as possible during rolling. Conventionally, for this purpose, An HC mill, a cross mill, or a 5- or 6-stage mill has been proposed. These rolling mills can perform crown control effectively to some extent, but their structure is special compared to the four-high rolling mill, so it takes a lot of effort to introduce them.
The drawback is that existing equipment must be significantly remodeled.

Therefore, the present applicant has already proposed a work roll shift rolling method that can perform crown control extremely effectively and can be incorporated into existing equipment without major modification (Japanese Patent Application Laid-Open No.
55-77903). To explain the outline of this method, as shown in FIG. 5A, the work rolls 6 and 7 have a configuration in which tapered portions 6b and 7b are formed at one end of the substantially cylindrical barrels 6a and 7a. The work rolls 6 and 7 are arranged one above the other so that the tapered portions 6b and 7b face in opposite directions, and back-up rolls 8 and 9 are arranged behind each of them. During rolling, the edges of the rolled material 5 are aligned at each tapered portion 6.
The work rolls 6 and 7 are reciprocated in the axial direction in a state where they are applied to the rollers a and 7a. According to the method proposed by the present applicant, the cylinders 6a, 7 of the work rolls 6, 7
Since the contact pressure with the back up rolls 8 and 9 at point a becomes smaller, no extra bending moment acts on the work roll, and the axial deflection deformation of the work roll decreases, as shown in Fig. 5B. Thus, the crown can be controlled advantageously. In addition, since the sudden change in roll flattening deformation at the edge portion of the rolled material 5 can be alleviated, there is no peculiar metal flow at the edge portion, and edge drop reduction can be effectively controlled.
Overall, strips with good shape and profile can be obtained.

Problems to be Solved by the Invention In the above-mentioned work roll shift rolling method, the work roll is reciprocated in the axial direction with the edge of the rolled material hanging on the tapered part of the work roll. The area near the boundary between the two parts tends to wear out earlier than other parts, and if the amount of wear exceeds a predetermined value, functions such as crown control and edge drop reduction cannot be performed. In such a case, conventionally, the work roll is replaced and the removed work roll is ground in a roll shop to reproduce the shape of the work roll to the shape at the initial stage of rolling.

In such a conventional method, the work rolls have to be replaced frequently (approximately 6 times/day), resulting in poor rolling efficiency and a problem in that the roll schedule is severely restricted.

Means for Solving the Problem In order to solve the above-mentioned problems, this invention
It is an object of the present invention to provide a method for prolonging the service life of a work roll having a tapered portion at one end by grinding the work roll while it is assembled on a rolling stand. That is, in the method of the present invention, a pair of work rolls each having a tapered portion continuously formed at one end of a substantially cylindrical body are arranged one above the other so that the tapered portions face in opposite left and right directions. death,
In addition, when rolling is performed using a work roll shift rolling machine that reciprocates the work roll in the axial direction during rolling, the roll grinder that presses the grinding belt against the work roll can reciprocate in a direction parallel to the work roll. The taper shape at the initial stage of rolling is reproduced by grinding the tapered portion with the roll grinder when a predetermined condition is reached after the start of rolling, and further rolling is performed to achieve the predetermined condition. The present invention is characterized in that when the second condition is reached, the barrel is ground by a roll grinder.

Example Next, embodiments of the invention will be described.

FIG. 1 is a schematic diagram showing an apparatus for carrying out the method of the present invention, in which a pair of work rolls 6 and 7 are shown.
As shown in FIG. 5A mentioned above, the trunks 6a and 7a
It has a structure in which tapered parts 6b, 7b are continuously formed at one end, and each work roll 6, 7 is arranged vertically so that its tapered parts 6b, 7b face in left and right opposite directions, and reciprocates in the axial direction. is configured to operate. Backup rolls 8 and 9 are arranged behind each work roll 6 and 7, that is, above the upper work roll 6 and below the lower work roll 7, respectively.

Above and below the rolled material 5 passing between the work rolls 6, 7, guide shafts 10, parallel to the axes of the rolls 6, .
Roll grinders 12 and 13, which are controlled online and reciprocate in parallel with the work rolls 6 and 7, are connected to guide shafts 10 and 11.
It is attached to 11. Roll grinder 1
2 and 13 have platen rods 16 and 17 that move forward and backward toward the work rolls 6 and 7 by hydraulic cylinders 14 and 15, and elastic members 1 such as springs are attached to the tips of the platen rods 16 and 17.
platen 20 receiving extrusion force from 8 and 19;
21 is built in, and the grinding belts 22 and 23 passing through the front side of the platens 20 and 21 are pressed against the outer surfaces of the work rolls 6 and 7. Here, the grinding belts 22 and 23 are long belt-shaped base materials to which abrasive grains are attached, and are fed from feed reels 24 and 25 provided on the main bodies of the roll grinders 12 and 13 to the platens 20 and 23.
1 and is wound around take-up reels 26 and 27. The feeding speed of the grinding belts 22, 23 is 1 to 3 m/min, and the feeding speed is opposite to the direction of rotation of the work rolls 6, 7.

Note that load cells 28 and 29 are disposed between the elastic members 18 and 19 and the platen rods 16 and 17, and the hydraulic cylinder 1 is activated based on the output signals of the load cells 28 and 29.
4 and 15 to adjust the amount of advance of the platen rods 16 and 17, the grinding belts 22 and
The pressing force of 23 is controlled to 100 to 400 kg. Although not specifically shown, the drive mechanism for moving the roll grinders 12, 13 along the guide shafts 10, 11 is constituted by a chain or a fluid pressure cylinder, and the running speed of the roll grinders 12, 13 is 1 to 1. It is set at about 2m/min.

In plate rolling by the above-mentioned work roll shift rolling machine incorporating the roll grinders 12 and 13, the work rolls 6 and 7 are moved in a state where the edge portion of the rolled material 5 is applied to the tapered portions 6b and 7b of the work rolls 6 and 7. This is done by reciprocating in the axial direction. Therefore, as shown in FIG. 2A, the tapered portions 6b and 7b, which are not worn at the beginning of rolling, are affected by friction with the edge portions of the rolled material 5 due to continuous rolling. A worn part D as shown is generated. The amount of wear is approximately proportional to the rolling tonnage, and there is a limit amount of wear that does not affect the shape or profile of the product, so the predetermined condition in this example is that the depth h of the worn part D is the limit amount. Before the rolling amount reaches a predetermined tonnage, the tapered parts 6b and 7b are ground to reduce the wear part D.
Eliminate. FIG. 2C shows the tapered shape after grinding. Such grinding of the tapered portions 6b, 7b is carried out by moving the roll grinders 12, 13 to positions corresponding to the tapered portions 6b, 7b when the rolling tonnage reaches a predetermined tonnage, and then grinding the grinding belt at that position. 2
2, 23 are pressed against the tapered parts 6b, 7b by the platen rods 16, 17 and platens 20, 21, and the grinding belts 22, 23 are run in the opposite direction to the rotational direction of the work rolls 6, 7, and 12 and 13 are reciprocated in the axial direction of the work rolls 6 and 7. In that case, as the roll grinders 12, 13 reciprocate, the distance between them and the tapered portions 6b, 7b changes, but the pressing force of the grinding belts 22, 23 is controlled by the output signals of the load cells 28, 29, which are applied to the platen rods 16, 17. It can be kept constant by adjusting the amount of protrusion.

Furthermore, by grinding the tapered portions 6b, 7b, the boundary with the cylinders 6a, 7a is shifted by a predetermined distance δ toward the cylinders 6a, 7a. 7 is determined in the axial direction by taking into consideration the deviation dimension δ, and is caused to reciprocate in the axial direction.

By the way, the surface roughness of the work rolls 6 and 7 is not as noticeable as the wear due to friction with the edge portion of the rolled material 5, so as described above, the surface roughness of the tapered portions 6b,
At the time point 7b has been ground, the surfaces of the cylinders 6a, 7a of the work rolls 6, 7 are in a state where rolling can be continued. Therefore, after grinding the tapered portions 6b and 7b to reproduce the tapered shape at the beginning of rolling, rolling is continued.

By further rolling, the tapered portion 6b,
Abrasion occurs on the edge portion 7b of the rolled material 5, and along with this, the surface roughness of the cylinders 6a and 7a progresses. Since the surface roughness of the cylinders 6a, 7a is also approximately proportional to the rolling tonnage, the second condition in this embodiment is the rolling tonnage after the start of use of the work rolls 6, 7, or the rolling tonnage of the cylinders 6a, 7a previously carried out. When the rolling tonnage after grinding reaches a predetermined tonnage, the cylinder 6a,
Perform the break-in grinding in step 7a. That is, the roll grinders 12, 13 are reciprocated several times in the axial direction of the work rolls 6, 7 while the grinding belts 22, 23 are pressed against the surfaces of the cylinders 6a, 7a.

FIG. 3 is a block diagram showing the above-mentioned grinding procedure. In other words, by inputting the weight or dimensions of the seat bar into the central processing unit CPU,
The sequential rolling tonnage is input. On the other hand, the taper part 6
The limit amount h of the worn part D that occurs on b and 7b is about 40 μm, and since such wear occurs when rolling 200 to 500 tons, it is necessary to set the cumulative rolling tonnage in the range of 200 to 500 tons in advance. When the predetermined amount is reached, the roll grinders 12 and 13 are driven to grind the tapered portions 6b and 7b as described above. In that case, the amount of grinding is as follows:
The required amount of grinding is determined by known controllable factors such as the pressing force, the relative speed difference between the grinding belts 22, 23 and the work rolls 6, 7, the grain size of the grinding belts 22, 23, and the time, so the amount of grinding required depends on the grinding time. to control.
In other words, the roll grinders 12 and 13 are stopped by an off signal as a predetermined grinding time elapses.
It returns and finishes grinding the tapered portions 6b and 7b.
At the same time, the integrated value of rolling tonnage for grinding the tapered portions 6b and 7b is reset to zero.

On the other hand, the cylinders 6a and 7 in the work rolls 6 and 7
The surface roughness of a usually reaches its limit after rolling 1,000 to 1,500 tons, so the rolling tonnage accumulated to determine the timing of leveling grinding must be 1,000 to 1,000 tons.
When a predetermined amount in the range of ~1,500 tons is reached, the roll grinders 12 and 13 are driven to carry out level grinding of the cylinders 6a and 7a as described above to correct rough surfaces. Also in this case, since the amount of grinding is determined by known and controllable factors, the roll grinders 12 and 13 are stopped and returned to their original positions by the off signal that accompanies the elapse of a predetermined grinding time, and the cylinders 6a and 7
Finish the break-in grinding of a. Also, the integrated value of rolling tonnage for leveling and grinding of the cylinders 6a and 7a is reset to zero.

In addition, depending on the type of steel to be rolled and rolling conditions, etc.
In some cases, the rolling tonnage, or period, during which the barrels 6a and 7a are ground-in is several times the rolling tonnage, or period, during which the tapered portions 6b and 7b are ground; in such a case, Torso 6a, 7
During the break-in grinding period a, the taper portion 6
Grinding of b and 7b will be performed multiple times. Also, the grinding timing of the cylinders 6a, 7a and the taper portion 6b,
If the grinding timing of 7b matches,
Of course, both can be ground simultaneously according to the respective grinding conditions.

Furthermore, since the profile of the rolled material 5 is generally constantly monitored by a profile meter, the tapered portions 6b, 7b of the work rolls 6, 7 are determined based on the detection signal of the profile meter.
In addition to managing the grinding timing based on the rolling tonnage mentioned above, if an abnormality such as local wear or rough skin of the cylinders 6a and 7a is detected, the detection signal of the profile meter is input to the central processing unit CPU, and the profile meter Taper part 6 based on the abnormal signal from
b, 7b or the cylinders 6a, 7a may be ground.

The above-mentioned grinding of the work rolls 6, 7 is performed during rolling while the work rolls 6, 7 are attached to the rolling stand, but by repeatedly performing such grinding, the outer diameter decreases and the neck portion is Since maintenance is also required, the work rolls 6 and 7 are finally removed from the rolling stand and replaced with new work rolls, and the removed work rolls are subjected to repair work such as grinding in the roll shop.

Effects of the Invention As is clear from the above description, according to the method of the present invention, local wear and roughness of the body due to rolling in the tapered portion of the work roll can be removed by grinding the work roll while it is attached to the rolling stand during rolling. Since the work rolls can be removed and corrected by removing and correcting them, the service life until the work rolls need to be replaced is significantly extended compared to the conventional method. Efficiency can be significantly improved.
In addition, the roll grinder for grinding the taper part and leveling the barrel can be controlled online according to the method of this invention, and in such a case, restrictions on the roll schedule can be significantly reduced.
In turn, continuous casting and hot rolling can be easily synchronized, and excellent practical effects can be obtained, such as a reduction in heating furnace consumption.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an apparatus for implementing the method of the present invention, and FIGS. 2A, B, and C are partial explanatory diagrams showing the process of changing the shape of the work roll near the boundary between the body and the tapered part. FIG. 3 is a block diagram showing the grinding procedure, FIG. 4A is a schematic diagram showing the arrangement of rolls in a four-high rolling mill, FIG. 4B is a diagram showing a profile obtained by the four-high rolling mill, and FIG. FIG. 5A is a schematic diagram showing the arrangement of rolls in a work roll shift rolling mill, and FIG. 5B is a diagram showing a profile obtained by the rolling mill. 5... Rolled material, 6, 7... Work roll, 6
a, 7a... body, 6b, 7b... taper part, 1
2, 13... Roll grinder, 22, 23...
Grinding belt, D...wearing part.

Claims (1)

[Claims] 1 A pair of work rolls each having a tapered portion continuously formed at one end of a substantially cylindrical cylinder are arranged one above the other so that the tapered portions face in left and right opposite directions, and the rolls are When rolling is performed by a work roll shift rolling machine that reciprocates a work roll in the axial direction, a roll grinder that presses a grinding belt against the work roll is arranged so as to be able to reciprocate in a direction parallel to the work roll, After the start of rolling, when a predetermined condition is reached, the tapered portion is ground by the roll grinder to reproduce the taper shape at the initial stage of rolling, and rolling is further performed to reach a predetermined second condition. 1. A method for grinding a work roll in a work roll shift rolling mill, characterized in that when the body is ground, the body is ground by a roll grinder.