JPH02303612A - Method for grinding roll - Google Patents

Abstract

PURPOSE:To execute the grinding work of stability by installing the rotary shaft of a grinder shifting from the rotary shaft of the roll by the amt. of offset and setting the relation between the amt. of offset and the dimension of the grinder in a specified relation at the time of grinding the roll without driving the grinder forcibly. CONSTITUTION:In a frame which is able to move back and forth along the axial line OR of a work roll 1 plural grinder holders 6 pushing the grinder 3 set at its end part on the roll surface are arranged in the axial direction of the roll. The above grinder is set in the above holder with its rotary shaft inclined to the roll axial direction against the perpendicular line on the roll surface and with its rotary shaft 4 shifted by the amt. of the offset H from the rotary shaft line of the above roll. On the method of grinding the above roll without forcedly driving the grinder, the relation of the amt. of offset H and dimensions of grinder D, d is set within the range of equation I and equation II, and therefore the grinding work of stability is executed without generating cracking of the grindstone, the bad vibration and the baking, etc.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a rotating roll grinding device.

In particular, the present invention relates to a method for corrective grinding of rolls on-line when the rolls are worn out during rolling operations, such as work rolls of rolling mills.

It can also be applied to an online grinding method for pinch rolls installed in front of a town coiler, and a grinding method for work rolls and backup rolls of various rolling mills.

[Conventional technology]

In hot rolling mills etc. that roll steel plates etc.

In order to improve production efficiency and improve the quality of rolled plate materials, it is desired to develop and put into practical use an online roll grinding device that attaches the grinding device directly to the rolling mill and grinds the roll surface to the desired profile while rolling. .

Fig. 8 shows an example of such an online roll grinding method, in which a grinding body 3 such as a non-rotating grindstone is pressed against the surface of the work roll 1 while rotating the work roll 1, and the work roll 1 is rotated in the direction of the roll axis, that is, perpendicular to the plane of the paper. By moving in the direction of , the surface of the work roll 1 is ground to a desired groin. Also, Figure 9 shows another example,
In this method, the rotating grinding belt 3' is pressed against the rotating work roll 1 in the same way as in the previous example, and the grinding belt 3' is moved in the roll axis direction to carry out grinding.

Furthermore, Fig. 10 shows that by offsetting the rotation axis Oc of the grinding body 3 by an amount H with respect to the rotation axis OR of the roll, it is possible to grind the roll 1 even without a forced drive device for the grinding body 3. In the apparatus of the method shown in FIG. 8, the structure is simple because there is no rotation drive device for the grinding body 3.

Since the surface of the grinding body 3 that comes into contact with the work roll 1 is always the same surface, clogging occurs on that surface.

There is a drawback that the grinding performance decreases. Furthermore, the grinding body 3 usually uses square block-shaped grindstones, and a device is used in which a plurality of these are arranged in the direction of the roll axis to increase grinding efficiency with a wide grinding surface, but in this case, the corners of the grinding body 3 There is a drawback that the portion 3a is easily damaged due to grinding resistance or the like.

On the other hand, in the apparatus of the type shown in Fig. 9, since the grinding body 3' rotates, the new grinding surface always comes into contact with the work roll 1 during grinding, so clogging of the surface of the grinding body 3' can be prevented and the grinding performance can be improved. There is also the advantage of being able to maintain it. Also, in this case, the grinding body 3'
Since a belt-shaped grindstone is usually used, it is possible to prevent the corner breakage that occurs with the square block-shaped grindstone. However, this method requires a rotary drive device (not shown in the figure) to rotate the grinding body 3', which makes the structure complicated, increases equipment costs, and requires very little maintenance and inspection of the equipment because the installation space is narrow. This is difficult, and the rotary drive space is large, which reduces the number of heads of the grinding body (usually only one head) and reduces the grinding performance when grinding the entire roll.

The first method proposed as a solution to the above problems was
This is the non-driven online grinding device shown in the figure. This method has the advantage that stable grinding performance can be obtained because the grinding body can perform grinding while rotating with the roll without the need for a forced drive device for the grinding body. However, one method was used to actually grind a rolling roll in an actual rolling facility.

The grinding body generated chatter vibration, which caused problems such as unstable grinding performance and chipping of the outer circumferential surface of the grinding body.

The present invention provides a rational method for eliminating the drawbacks of the above-mentioned rotating body grinding device. A plurality of grinding body holders that press the grinding bodies against the roll surface are arranged in the roll axis direction, and the grinding bodies are installed in the holders with their rotational axes tilted in the roll axis direction with respect to the normal to the roll surface, and the grinding bodies In a method of grinding the roll without forcibly driving the grinding body by mounting the rotation axis of the body offset by an offset amount H with respect to the rotation axis of the roll, the offset amount H
This is a roll grinding method characterized in that the relationship between the dimensions DG and da of the grinding body is set within the range of the following equation.

0, f ≦H/Da <0.4 0.1<dG/DG where H: Offset amount between the rotational axis of the grinding body and the roll rotation axis dC: Inner diameter of the grinding body DG = Outer diameter of the grinding body [ Effect] By setting the offset amount H applied between the rotation axis of the grinding body and the rotation axis of the roll to the above-mentioned value, the relative sliding speed VS generated at the contact portion between the grinding body and the roll to be ground is reduced.
The direction is correct and vibration and chipping of the grinding body can be prevented. Further, by setting the inner diameter of the grinding body to the above-mentioned value, the direction of the relative sliding speed, which will be described later, can be prevented from coinciding with the contact line, thereby preventing seizure and clogging of the grinding body.

〔Example〕

Hereinafter, the structure and operation of the present invention will be explained in more detail based on the embodiments shown in the drawings. FIG. 1 is a plan view showing an embodiment of the roll grinding device of the present invention applied to, for example, an upper work roll of a four-high rolling mill, and FIG. 2 is a sectional view taken along the line A--A in FIG. 1.

As shown in the figure, the rolling mill rolls a rolled plate material 15 using work rolls 1, and the work rolls 1 are reinforced by backup rolls 2. A plurality of grinding bodies 3, such as ring-shaped grindstones, arranged in the axial direction of the work roll are each rotatably supported at the tip of a grinding body holder 6 via a shaft 4 and a bearing 5, respectively. In the following explanation, the grinding body 3 is the grindstone 3, and the grinding body holder 6 is the grindstone holder 6.
It shall be written as.

Each grindstone holder 6 forms a plunger, the rear part of which is a pressing device 8 consisting of a granger 8a and a cylinder 8b.
It is fitted into the casing 9 so as to be able to move back and forth in the direction of the arrow X.

Each pressing device 8 is attached to the inside of the rear cover 9a of the casing 9, and by supplying hydraulic oil from the hole 10 to the cylinder 8b via a hydraulic control valve (not shown), the grinding wheel 3 is moved onto the surface of the work roll 1 at an arbitrary set pressure. can be pressed.

Incidentally, the casing 9 is provided with an oil supply port 12 to a pullback cylinder chamber 11 for the grindstone holder. Further, as shown in FIG. 1, the rotational axis OG of each grinding wheel 30 is installed in the casing 9 so as to be inclined in the roll axis direction at an arbitrary set angle α with respect to the normal N to the outer peripheral surface of the work roll 1. By raising and lowering the casing 9 using the casing 13, it is possible to offset the rotation axis Oc of the grindstone 30 upwardly or downwardly with respect to the work roll axis OR. The illustrated example shows a case where the setting value H is offset upward.

FIG. 3 is an explanatory diagram showing the contact state of the grinding body with the roll. When the grinding wheel rotation axis OG is offset with respect to the work roll axis OR as described above, the work roll 1 on the tip surface of the grinding wheel 3 during grinding is The contact portion with the grinding surface, that is, the grinding surface, becomes a line contact l as shown in FIG.

In such a contact state, the work roll 1 has a circumferential speed Vc
When the grindstone 3 rotates at a circumferential speed of G, a relative sliding speed Vs occurs between the grindstone 3 and the roll 1. The surface of the roll 1 is ground by this sliding speed Vs.

On the other hand, when performing roll grinding, the most important thing is to maintain stable grinding characteristics without chipping or seizure of the grindstone. To this end, it became clear during actual machine tests that the direction of the aforementioned slip velocity Vs is extremely important. In other words, if the offset of the grinding wheel is small, the grinding wheel is likely to chatter and break, while if it is too thick, the grinding wheel is likely to seize.
In either case, normal grinding was impossible.

In order to solve these problems, we conducted actual machine tests and theoretical analyzes and found that in order to achieve stable grinding, there is an important relationship between the offset amount H and the grinding wheel dimensions, Da, (iG) as shown in the first order. Ta.

Figure 5 shows the offset amount H (ratio H/to the grinding wheel outer diameter).
DG) and the inner diameter of the grinding wheel (ratio d to the outer diameter of the grinding wheel)
This table summarizes the grinding characteristics when grinding a roll by making various changes to the grinding characteristics (organized by G/DG). The grinding conditions at this time are shown below.

Roll material: 22 grain cast iron Roll outer diameter: Dw = Φ600m Roll circumferential speed + 800m Grinding wheel material: GC320 Grinding wheel outer diameter: Φ240 wa The vertical axis in this figure shows the grinding ratio G, which is defined by the following formula be done.

The larger the grinding ratio G is, the less wear and tear there is on the grinding wheel, which means that the life of the grinding wheel is longer.

Therefore, it is desirable to grind under conditions where the grinding ratio G is high, and when looking at Figure 6 from this perspective, da/D
It is better to make c small and H/Dc large.

However, if dG/DG, that is, the inner diameter of the grinding wheel, is made smaller, seizure will occur from the inside of the grinding wheel, making the grinding performance very unstable. Burn-in cannot be prevented even if the

On the other hand, even if the grinding wheel offset amount (represented by H/DG in Fig. 5) is increased, seizure occurs, and in this case too, seizure occurs on the inner circumferential side of the grinding wheel, and it is necessary to prevent seizure. It is necessary to make H/Dc<0.4.

Next, we will explain why such seizure of the grindstone is affected by dG and H that occur on the inner peripheral side of the grindstone.

FIG. 6 shows vector analysis results of the aforementioned sliding speed VS under various grinding conditions.

The slip velocity Vs at any point on the contact line l between the grindstone and the roll is shown as a vector, and it can be seen that the direction changes greatly depending on the grindstone offset amount H and the grindstone inner diameter dG.

That is, as the grindstone offset amount H increases, the direction of the sliding speed VS overlaps the contact line in the inner portion of the grindstone.

In this way, in a portion where vs and l match, heat generated by grinding is stored in this portion, causing seizure.

Therefore, in order to prevent the grinding wheel from seizing, it is necessary to prevent the sliding speed Vs from matching the contact line j.
The measures include (1) appropriate grinding wheel offset amount and (2)
) It is essential to set the appropriate grindstone inner diameter.

As described above, from the viewpoint of preventing seizure of the grindstone, it is best to make H/Da as small as possible, but if it is too small, chatter vibration of the grindstone will occur.

Figure 5 shows the relationship between chatter vibration and grinding conditions.

When H/DG becomes 0.1 or less, chatter vibration is likely to occur, and when H/Da becomes even smaller, it induces chipping of the grindstone.

The causes of such chatter vibration and grinding wheel breakage are also shown in Figure 1. This can be explained as follows from the difference in the direction of the slip velocity VS.

The chattering vibration of the grinding wheel is likely to occur when the offset amount H is small in the direction of the sliding speed VS.

Because there is a large difference between the inside and outside of the grindstone (Figure 6 (in N, VS includes downward and upward directions), the direction of the external force (grinding resistance force) acting on the grindstone rotation axis is expanded, and its This is because the deformation mode becomes complicated.

Also, when the grindstone offset amount H is small.

The grindstone is likely to be damaged, but this is because the direction of the relative sliding speed Vs at the outer circumference of the grindstone is directed toward the outer circumference (normal direction) of the grindstone.

In other words, at any point on the roll contact line l, a grinding resistance force in the sliding speed direction will act on the grinding wheel, but inside the contact line l, it is a downward resistance force that has no bearing on the grinding wheel chipping. On the other hand, the strength of the whetstone is weak at the outer periphery, and it is relatively easy to break even with a small external force. In this case, the more the direction of the resistance force received from the rolls, that is, the direction of the sliding speed, is toward the outer circumference of the grindstone, the more likely it is to break.

Therefore, in preventing the chipping of the whetstone.

It is necessary to prevent the direction of the sliding speed from pointing toward the outer circumferential direction as much as possible, and as a measure for this, it is important to optimize H/Da.

As described above, the relationship between the seizure, chatter vibration, and chipping of the grindstone and the amount of grindstone offset and the inner diameter of the grindstone is summarized and the appropriate range is illustrated in FIG. 7. The appropriate range is 0.1≦H/Dc≦0.4゜0.1≦dc/Dc as shown in this figure (C).
It is.

〔Effect of the invention〕

According to the grinding method of the present invention, stable grinding can be performed directly in equipment such as rolling equipment without causing chipping of the grindstone, chatter vibration, seizure, etc., even without a forced rotation drive device for the grinding body. The efficiency of rolling operations, etc. improves, and at the same time, the quality of rolled products, etc. improves.

[Brief explanation of drawings]

FIG. 1 is a plan view of a roll grinding device as an embodiment of the present invention, FIG. 2 is a sectional view taken along line A-A in FIG. 1, FIG. 3 is a principle diagram of the roll grinding device of the present invention, and FIG. An explanatory diagram of the same grinding principle as above. Figure 5 is a graph of the grinding test results showing the relationship between grinding conditions and grinding characteristics. Figure 6 is (A) (B) (C) (D
) (E) is a graph diagram showing an example of the theoretical analysis results of the contact state and relative sliding speed between the grindstone and the roll according to the present invention,
FIGS. 7(A), 7(B), and 7(C) are explanatory diagrams showing the proper relationship between the grinding wheel (Offcera) H and the dimensions Da and dc of the grinding wheel claimed in the present invention. FIG. 8, FIG. 9, and FIG. 10 are principle diagrams showing an example of a conventional roll grinding device. DESCRIPTION OF SYMBOLS 1... Work roll of a rolling mill, 2... Rolling machine pick-up roll, 3... Grinding body (grindstone), 4... Grinding body rotating shaft, 5... Same left bearing, 6...・Grinding body (grindstone) holder, 8...Plunger for pressing the grinding body, 9...
・Casing, 10...Pushing is hydraulic pressure supply hole. Machining 1... Grinding body pull pack, 12... Pull pack hydraulic pressure supply hole, 13... Grinding body lifting device, 14... Grinding body oscillation device, H... Grinding body (grinding wheel) offset amount, OR ...Work roll rotation axis center, Oc...
- Grinding body (grinding wheel) rotation axis, l... contact line between grinding wheel and roll, dG... inner diameter of grinding body (grinding wheel), ■... outer diameter of grinding body (grinding wheel).

Claims (1)

[Scope of Claims] A plurality of grinding body holders for pressing a grinding body attached to the tip against the roll surface are arranged in the roll axis direction in a frame capable of reciprocating along the roll axis, and the grinding body is rotated by the rotation of the grinding body. The grinding body is mounted in the holder with the shaft tilted in the roll axis direction with respect to the normal to the roll surface, and the rotation axis of the grinding body is shifted by an offset amount H with respect to the rotation axis of the roll. A method for grinding a roll without forcibly driving the roll, characterized in that the relationship between the offset amount H and the dimensions D_G and d_G of the grinding body is set within the range of the following formula. 0.1≦H/D_G≦0.4 0.1≦d_G/D_G where H: Offset amount between the rotation axis of the grinding body and the rotation axis of the roll d_G: Inner diameter of the grinding body D_G: Outer diameter of the grinding body