JP2006181630A - Method for grinding outer layer of roll with on-line roll grinder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grinding method of the outer layer of a roll with an on-line roll grinder in which the prime object is put to the performance of grinding at a certain depth without depending on cumulative rolling load in the depth direction from the roll surface. <P>SOLUTION: The pressing linear pressure to the roll of the grinding whetstone of the on-line roll grinder is varied in accordance with the cumulative rolling load in the depth direction from the roll surface. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for grinding a roll surface layer using an on-line roll grinder.

  When rolling a metal piece with a rolling mill, a fatigue layer due to rolling fatigue is gradually formed on the roll surface layer in contact with the material to be rolled.

  This rolling fatigue is the effect of the rolling reaction force that tries to deflect the roll when viewed on a straight line in the roll axis direction on the roll surface. It is caused by repeatedly pulling, compressing, or extending in the direction.

  Cumulative rolling load (generally expressed as the cumulative rolling amount or rolling distance or the product of both) calculated from the state immediately after polishing with a new roll or roll shop or immediately after polishing with an online roll grinder As the depth increases, the depth from the roll surface of cracks caused by rolling fatigue increases.

  This cracked region that reaches a certain depth is called the fatigue layer described at the beginning.

  This fatigue layer is formed not only in the case of cold rolling but also in the case of hot rolling. In the case of hot rolling, since the material to be rolled is as high as several hundred to several hundreds of degrees Celsius, the effects of thermal fatigue and heat cracks due to heat input from the material to be rolled to the roll side are also fatigue layers. Will participate in the formation of.

  When the fatigue layer progresses, the roll surface layer is destroyed and chipped due to the fatigue layer, and immediately after polishing in a new roll or a roll shop described later, or by an online roll grinder described later used in the present invention. The roll surface layer at the same site is more uneven than the state immediately after the entire surface is polished, and if the rolling is continued as it is, the unevenness is transferred to the material to be rolled, and the surface quality of the product is impaired.

  Therefore, conventionally, a roll that has finished a certain amount of rolling is extracted from the rolling mill, the surface layer is replaced with a polished roll, and the extracted roll is carried into a roll surface grinding ground called a roll shop, The roll was ground and removed by a grinder by an amount corresponding to the thickness of the fatigue layer determined based on the rolling amount or rolling distance after the rolling.

  However, as a result of frequent work of extracting the roll from the rolling mill and replacing it with a polished roll, there has been a problem of reduction in operating rate and production efficiency of production lines such as cold rolling and hot rolling. For this reason, Patent Document 1 proposes a method of grinding and removing the fatigue layer of the roll by an online roll grinder every time the cumulative rolling load of the roll reaches a predetermined amount.

  An outline of this online roll grinder is shown in FIG. 5, where (a) is a bird's eye view and (b) is a side view. The grinding unit 33 provided with the rotating grindstone 31 reciprocates (oscillates) in the roll axis direction, that is, the material width direction.

  FIG. 5C is an enlarged view of the main part of the online roll grinder. A rotating grindstone 31 for grinding a surface layer of a roll (work roll) 19 of a rolling mill is provided with a bearing box 39 via a bearing 35. Is supported rotatably. A grindstone rotating motor 37 supported on the bearing housing 40 via a bearing 36 is disposed coaxially with the rotating grindstone 31. The drive shaft 38 of the rotating grindstone 31 and the output shaft 41 of the grindstone rotating motor 37 are rotatably connected by a universal joint 42 with a spline. The bearing box 39 on the rotating grindstone 31 side is attached to a gantry 44 via a linear guide 43 and moves back and forth in the depth direction from the surface while being guided by the linear guide 43 by the operation of the pressing cylinder 34. The rotating grindstone 31 is pressed against the roll 19 by the forward movement. The gantry 44 of the pressing cylinder 34 is movable along the axial direction of the roll 19 as a part of the above-described grinding unit 33.

  The pressing cylinder 34 and the rotating grindstone motor 37 are controlled by commands from a drive control device (not shown). The drive control device is to be rolled based on data such as material and dimensions, which are stored in the business computer 54 and the process computer 52 in FIG. Each time a material is rolled, the rolling load of the roll is calculated in advance and accumulated in association with each roll currently in use. As the rolling load, for example, any one of the rolling amount (t) and the rolling amount × the rolling distance is adopted. Then, according to the model formula for the actual grinding amount with the cumulative rolling load and the pressing linear pressure of the rotating grindstone 31 and the relative sliding speed of the roll 19 and the rotating grindstone 31 as variables, the target grinding is performed with a predetermined grinding amount. The pressing linear pressure of the rotating grindstone 31 and the relative sliding speed of the roll 19 and the rotating grindstone 31 are controlled. The drive control device stores the grinding amount in a memory when grinding is performed.

  An example of a plan view of the rotating grindstone 31 is shown in FIG. 6. The grindstone is composed of, for example, 8 pieces and is arranged in a ring shape as a whole, the outer diameter of the ring is 200 mm, and the inner diameter is 120 mm. If the contact portion between the roll 19 and the rotating grindstone 31 (not shown) is A, the width w in the roll axial direction is determined, and the roll 19 has a width w in the roll axial direction. When the amount of movement of the contact portion A between the rotating grindstone 31 and the roll 19 is also constant at this width w, the phenomenon that the surface layer of the roll 19 is ground is caused by the load generated by the contact pressing between the rotating grindstone 31 and the roll 19 ( Pressing line pressure) and the number of times the roll 19 rotates and slides in a state where the rotary grindstone 31 and the roll 19 are in contact with each other. Incidentally, a region indicated by A ′ surrounded by a dotted line in the figure indicates a portion where the roll 19 contacts the roll grindstone 31 after the roll 19 has just made one round.

  In Patent Document 2, the roll grinding volume per unit time (hereinafter referred to as grinding ability) is expressed by the pressing linear pressure on the surface of the roll 19 of the rotating grindstone 31 and the relative sliding speed generated between the rotating grindstone 31 and the roll 19. The following regression formula has been proposed as an expression that represents the grinding ability.

^{Vg = a · P b · Vr} c ··· (1)
Vg: Grinding ability (cc / min)
P: Grinding wheel pressing linear pressure (kgf / mm)
Vr: Relative sliding speed (mpm)
(Vr = VR + VG, VR: roll peripheral speed (mpm), VG: rotating grindstone peripheral speed (mpm))
a, b, c: Grinding performance parameters These relationships are qualitative, but the grinding performance Vg increases as the grinding wheel pressing linear pressure P increases, and the grinding performance Vg increases as the relative sliding speed Vr increases. It is in.

When the equation of Patent Document 2 is applied to FIG. 6, the relative sliding speed Vr is accurately
Vr = VR + Vgcosθ
It becomes.

Further, the applicant has proposed in Patent Document 3 that the roll grinding volume per unit time, that is, the grinding ability is changed for each material to be rolled.
JP-A-10-328716 Japanese Patent Application Laid-Open No. 07-088513 Japanese Patent Laid-Open No. 2002-178012

  However, in the conventional grinding methods for the roll surface layer as shown in Patent Documents 1 to 3, a constant grinding stone pressing linear pressure and a constant relative sliding are used regardless of the cumulative rolling load in the depth direction from the roll surface. Since grinding was performed at a speed, the actual grinding ability when grinding while oscillating in the roll axis direction caused fluctuation due to the cumulative rolling load in the depth direction from the roll surface. As a result of grinding deeper than desired in a region where the rolling load is large, there is a problem that the roll basic unit may be deteriorated due to overgrinding.

  Therefore, the present invention has been made to solve this conventional problem, and is an on-line roll that focuses on grinding at a constant depth regardless of the cumulative rolling load in the depth direction from the roll surface. It aims at providing the grinding method of the roll surface layer by a grinder.

  The present invention is a method for grinding a roll surface layer using an on-line roll grinder, and changes the pressing linear pressure on the roll of the on-line roll grinder grindstone according to the cumulative rolling load in the depth direction from the roll surface. .

  According to the present invention, in the grinding method of the roll surface layer by the online roll grinder, the pressing linear pressure on the roll of the online roll grinder grindstone is changed according to the cumulative rolling load in the depth direction from the roll surface. The grinding can be performed at a constant depth regardless of the cumulative rolling load in the depth direction from the roll surface.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Grinding ability determination formula)
Assuming that one roll is taken, an example is shown in the following formula (2) as a model formula representing the grinding ability in consideration of the cumulative rolling load for the roll.

Vg = 9.8 (1 + d · L) · a · P ^b · Vr ^c (2)
Vg: Grinding ability (cc / min)
P: Grinding wheel pressing linear pressure (kN / mm)
Vr: Relative sliding speed (mpm)
(Vr = VR + VG, VR: roll circumferential speed (mpm), VG: grinding wheel circumferential speed (mpm))
a, b, c, d: Grinding ability parameter L: Rolling distance (km)
As a, b, c, and d in this expression, for example, the following value a = 0.0245
b = 0.692
c = 0.503
d = 0.00750
FIG. 1 shows the relationship between the pressing line pressure and the grinding ability.

  However, since the grinding parameters such as a, b, c, and d are considered to vary depending on the production type and size of the production line, the roll material, etc., they are not necessarily limited to the above values. Instead, it may be obtained by regression so as to match the actual measurement data, and may be adjusted as appropriate.

  Moreover, as a cumulative rolling load, it is not always necessary to use a rolling distance as in the above example. As a model expression representing grinding ability, for example, the following expression (3) different from the above (2) A model formula or a completely different model formula may be used.

Vg = 9.8φΣ (L × Pr) ÷ (D × W) · a · P ^b · Vr ^c (3)
Vg: Grinding ability (cc / min)
L: Rolling distance (km)
Pr: Rolling load of material to be rolled D: Roll diameter W: Width of material to be rolled P: Grinding wheel pressing linear pressure (kN / mm)
Vr: Relative sliding speed (mpm)
(Vr = VR + VG, VR: roll circumferential speed (mpm), VG: grinding wheel circumferential speed (mpm))
φ, a, b, c, d: Grinding performance parameter Σ: Indicates the sum of each material to be rolled.

By the way, in the above formula (3),
φΣ (L × Pr) ÷ (D × W)
This part is obtained by multiplying the linear pressure obtained by dividing the load Pr received from the material to be rolled by the material width W to be rolled by the number of rolling times obtained by dividing the rolling distance L of the material to be rolled by the roll diameter D. This is a parameter index indicating the rolling load applied to the roll. Here, the circumference ratio π is included in φ. Σ is summed for each material to be rolled, and the cumulative load is obtained by accumulating.

  This is reflected in the control of changing the pressing line pressure on the roll of the online roll grinder grindstone according to the cumulative rolling load in the depth direction from the roll surface, which is the point of the present invention. The pressing linear pressure is a value obtained by dividing the load at the time of pressing the rotating grindstone on the roll by the width w in the roll axis direction of the contact portion A between the roll and the rotating grindstone.

  An example of the case where the present invention is applied to the second stand F2 of the finishing mill 18 of the hot rolling line 100 as shown in FIG. 2 will be described below with reference to FIGS. A method for grinding the roll surface layer according to 30 will be described. In FIG. 2, 8 is a material to be rolled, 10 is No. 1 to 3 heating furnaces, 12 is a rough rolling mill of 3 stands of R1 to R3, 13 is a work roll thereof, 14 is a cropper, 16 is a descaling device, 18 is, for example, F1 to F7 7 is a finish rolling mill, 19 is its work roll, 30 is an online roll grinder for the work roll 19, 22 is a cooling zone, 24 is two coilers of DC1 to DC2, for example, 50 is a roll A control device 52 including a grinder drive control device, 52 is a process computer that gives a command to the control device 50, and 54 is a business computer that gives a command to the process computer 52. G and K each represent a transmission path.

  Instructed by the control device 50 including the roll grinder drive control device, the gantry 44 of the online roll grinder 30 is oscillated, the pressing cylinder 34 is moved, and the rotating grindstone 31 is moved from the standby position toward the surface of the roll 19. .

  When the rotating grindstone 31 reaches a predetermined position before reaching the surface of the roll 19, the grindstone rotating motor 37 is driven and the rotating grindstone 31 starts to rotate. The grindstone peripheral speed of the rotating grindstone 31 may be determined in advance, for example, to be fixed at a fixed value within a range of 3 to 100 mpm, for example, 30 mpm, and the roll peripheral speed may be various rolling materials. Since it fluctuates every time, it is also preferable to appropriately adjust the value so as to exhibit the desired grinding ability and the pressing line pressure corresponding thereto.

  Subsequently, in the process computer 52, a = 0.0245, b = 0.692, c = 0.503, d = 0. The required grinding ability is first obtained from the actual values such as the rolling distance L and the roll peripheral speed VR, and the necessary pressing line pressure is obtained from the relationship between the grinding ability and the pressing line pressure defined by the model formula.

  Then, the rotating grindstone 31 is pressed against the surface of the roll 19 by the operation of the pressing cylinder 34 shown in FIG. 5C so that the pressing linear pressure is obtained, and the rotating grindstone 31 is rotated to grind the surface layer of the roll 19. Begins.

  The pressing cylinder 34 or a hydraulic system supplied to the pressing cylinder 34 is provided with a hydraulic pressure gauge (not shown) so that the detected hydraulic pressure reaches a value corresponding to a desired pressing linear pressure. A command is sent from the control device 50 to control the hydraulic pressure. In order to control the hydraulic pressure, a servo valve is preferably installed in a hydraulic system for operating the pressing cylinder 34, and the hydraulic pressure is preferably controlled by pressure control using the servo valve.

  The rotating grindstone 31 is ground along with the movement of the gantry 44 from one end side to the other end side of the roll 19 in the axial direction, and after grinding is performed according to the cumulative rolling load sequentially after necessary grinding performance, Then, the pressing cylinder 34 moves in the backward direction, and the rotating grindstone 31 is retracted. Thereafter, the rotating grindstone 31 moves to the standby position together with the gantry 44 to prepare for the next grinding.

  As a result of grinding by such a grinding method, the roll basic unit was reduced by about 10% compared to the conventional one without impairing the surface quality of the product.

  In the above example, the case where the present invention is applied to the second stand F2 of the finish rolling mill 18 of the hot rolling line 100 as shown in FIG. 2 has been described as an example. It may be applied to the stands F1 and F3 to F7 of the rolling mill, or may be applied to the stands R1 to R3 of the roughing mill 12, and hot rolling provided with a slab continuous casting facility 6 as shown in FIG. Of course, it may be applied to the stands F1 to F7 of the finishing mill 18 of the line 200, or may be applied to the stands F1 to F5 of the finishing mill 18 of the cold rolling line 300 as shown in FIG.

  In FIG. 4, 61 is a plurality (two in the figure) of unwinding reels, 62 is a joining machine for joining the rolled material 8 unwound from different unwinding reels 61 to form a continuous band, 63 Loop equipment provided on the entry side and exit side of the finish rolling mill 18, 65 is a cutting machine for cutting the rolled material 8 after rolling again at a predetermined length, and 66 is cut by the cutting machine 65. This is a take-up reel for rewinding the rolled material 8 again.

  INDUSTRIAL APPLICABILITY The present invention is a method for grinding a roll surface layer using an on-line roll grinder that can be widely applied to the rolling of steel and other metals, and has the effect of improving the roll basic unit without impairing the surface quality of the product.

The diagram which showed the relationship between the grinding ability of a roll by an on-line roll grinder, and pressing linear pressure at the time of following this invention. The figure which shows an example of the rolling line which should apply this invention. The figure which shows the other example of the rolling line which should apply this invention. The figure which shows the other example of the rolling line which should apply this invention. The figure which illustrates and shows the online roll grinder used for this invention. The figure which illustrates the relationship between the rotating grindstone of an on-line roll grinder used for this invention, and a roll.

Explanation of symbols

6 Slab continuous casting equipment 8 Material to be rolled 10 Heating furnace 12 Rough rolling mill 13, 19 Roll (work roll)
DESCRIPTION OF SYMBOLS 14 Cropsha 16 Descaling device 18 Finishing mill 20 Backup roll 22 Cooling zone 24 Coiler 30 Online roll grinder 31 Rotating whetstone 32 Oscillating screw and nut 33 Grinding unit 34 Pressing cylinder 35, 36 Bearing 39, 40 Bearing box 37 Grinding wheel rotation Motor 38 Drive shaft 41 Output shaft 42 Universal joint with spline 43 Linear guide 44 Mounting base 50 Control device 52 Process computer 54 Business computer 61 Unwinding reel 62 Joining machine 63 Loop equipment 65 Cutting machine 66 Take-up reel 100, 200 Hot rolling line 300 Cold rolling line A Contact part between roll and rotating wheel

Claims (1)

In the grinding method of roll surface layer by online roll grinder,
A method of grinding a roll surface layer by an online roll grinder, wherein the pressing linear pressure on the roll of the online roll grinder grindstone is changed according to a cumulative rolling load in the depth direction from the roll surface.

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