JPH1015614A - Method for preventing contact between rolls - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply and surely prevent the contact of an upper roll with a lower roll and to extend the service life of the roll by arranging a spacer between an upper and a lower chocks at both ends of cermet thermal sprayed rolls and limiting the interval between the rolls at the time of non-passing a steel plate. SOLUTION: In a pinch roll rolling reduction device used for the rolling of the steel plate, the spacer 8 is arranged between the upper and the lower chocks 7a, 7b at both ends of the cermet thermal-spraying roll containing carbide so that the upper roll does not contact with the lower roll at the time of non-passing the steel plate. At this time, the thickness of the spacer 8 is selected so that the roll gap (d) at the time of non-passing the steel plate becomes in the range of 20-60% of the min. plate thickness of the steel plate passing through the rolling reduction device. Even in the case the diameter of the roll changes because of replacing the roll, etc., the method can simply cape with without drastically reconstructing the equipment by replacing only the spacer 8 having suitable thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing roll contact when a cermet spray roll containing carbide is used in a pinch roll press-down apparatus used in a rolling process of a steel sheet or the like.

[0002]

2. Description of the Related Art As shown in FIG. 1, a pinch roll lowering device has a structure in which a lower roll 1 is fixed to a rolling stand 3 and an upper roll 2 can move up and down along a shaft 4. By 5, a rolling force is applied to the upper roll 2.

Therefore, the upper and lower rolls come into contact with each other when the sheet is not passed, but when the rear end of the rolled steel sheet 6 passes between the rolls, the upper roll 2 suddenly descends and collides with the lower roll 1. An impact force is applied to the roll surface.

Conventionally, as a roll of a pinch roll pressing device, a surface hardening roll of a bearing steel, a build-up welding roll, or the like has been used. There was no risk of the roll being damaged, and it was not necessary to prevent the roll from contacting.

[0005]

However, in recent years, even in a pinch roll pressing device such as a cold rolling and pickling process, for example, tungsten carbide (WC) and other carbides have been used to improve the wear resistance and durability of the roll. Rolls sprayed with a cermet containing phenolic have been used, which has caused a problem of roll damage due to collision between upper and lower rolls.

That is, the cermet sprayed layer containing carbides on the roll surface is relatively weak in impact force, and the impact force applied to the roll when the rear end of the steel sheet passes may cause peeling of the surface sprayed layer. Therefore, a method for reliably preventing contact between the upper and lower rolls has been required.

Accordingly, an object of the present invention is to provide a method for simply and surely preventing contact between upper and lower rolls when a cermet spraying roll containing carbide is used in a pinch roll rolling device for a steel sheet.

In particular, it is an object of the present invention to provide a method for preventing contact of a roll without modifying a roll stand or other pressing device for preventing such contact and without adversely affecting operations such as rolling. I do.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the gist of the present invention is to use a cermet spraying roll containing carbide in a steel sheet pinch roll reduction device. Spacers are arranged between the upper and lower chocks at both ends, and the roll interval when the sheet is not passed is set to 20 to 60% of the minimum thickness of the steel sheet rolled by the reduction device.
A method for preventing contact of rolls.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 is an explanatory diagram of a method for preventing contact of a roll according to the present invention. 2A, the upper roll 2 and the upper chock (bearing portion) 7b are pushed up by the steel plate 6 as shown in FIG. 2A.
As shown in (b), the upper roll 2 is pressed against the lower roll 1 by a hydraulic cylinder (not shown). In particular, when the rear end of the steel plate 6 comes off, the upper roll 2 may drop suddenly and collide with the lower roll 1 to damage the cermet sprayed layer containing carbide on the roll surface.

Therefore, as shown in FIG. 2C, spacers 8 are arranged between the upper and lower chocks 7a and 7b at both ends of the roll so that the upper and lower rolls do not come into contact even when the sheet is not passed.

Since the spacer 8 has a function as a stopper, the spacer 8 needs to have a predetermined strength and impact resistance. Generally, a steel plate having a predetermined thickness and a predetermined area can be used. Further, the spacer needs to be fixed by some method so as not to fall off due to the vibration at the time of passing the plate. For example, the spacer may be detachably fixed to one of the upper and lower chock by screwing or other methods.

In the present invention, in order to completely prevent the contact between the upper and lower rolls and to have no adverse effect on the rolling and straightening operation by the pinch roll reduction device, the roll interval (when the upper and lower chocks are in close contact with the spacer) when the sheet is not passed through is set. It is important to select the thickness of the spacer 8 so that the roll distance d obtained when the spacer 8 is formed has an appropriate value.

[0014] The inventors of the present invention have studied variously the appropriate value of the roll interval d when the sheet is not passed, and d is in the range of 20 to 60% of the minimum sheet thickness t _min of the sheet passed through the rolling device. It was found that it was necessary to set within.

The reason why d is set to 20% or more of t _min is that below this, the upper and lower rolls may come into contact with each other for the following two reasons.

The spacer itself is worn and deformed by use for a long time. Rolling force applied to the hydraulic cylinders of the pinch roll gap control device, it is necessary to increase as the plate Atsudai by prolonged use of the spacer, 20% t _min
It has been empirically shown that deformation (reduction in spacer thickness) can occur to a degree.

[0017] during the supply plate, the rolling force of the rolls at both ends of the hydraulic cylinder, the deflection of about 20% of t _{mi n} vertically rolls that occurs is known empirically, the rear end of the steel sheet leaves the between the rolls When this occurs, the bending becomes a repulsive force and the upper and lower rolls may come into contact with each other.

The reason why d is limited to 60% or less of t _min is to prevent the rolling force from working when the roll is worn. That is, (a decrease in roll radius of up to wear site) prolonged wear of the roll through the use are known to empirically ranging about 20% of t _min, d is more than 60% of t _min In this case, the rolling force does not act on the steel sheet having the minimum thickness, and the steel sheet may not function properly as a pinch roll.

Means for providing a stopper for preventing the contact of the roll include, in addition to the method of the present invention, a method of modifying the chock itself, a method of providing a roll stand or a hydraulic cylinder with a stopper function, and the like. . However, these methods often require significant remodeling when the roll diameter changes, and cannot be easily handled.

On the other hand, according to the method of the present invention, even when the roll diameter changes due to roll replacement or roll repair (build-up, thermal spraying, etc.), the spacer is replaced with a spacer having a thickness corresponding to the roll diameter. Therefore, it is a great advantage that it can be easily handled.

[0021]

EXAMPLE When a cermet sprayed roll containing carbide was used as an uncoiler pinch roll in a continuous pickling apparatus at a cold rolling mill, the method for preventing contact between rolls according to the present invention was carried out.
FIG. 3 is a schematic view of a pinch roll rolling down device in the present embodiment.

The pinch roll has a diameter of 300 mm and a body length of 1800.
mm, a spacer 8 between the upper and lower chocks 7a, 7b at both ends.
Is provided to prevent contact of the roll when the sheet is not passed. The spacer is made of a steel plate having an area of 330 × 330 mm and a thickness of 20 mm. As shown in FIG. 3, a backing plate is joined to one end in an L-shape and fixed to the lower chock 7a with bolts and nuts.

The pinch roll pressing device of this embodiment is for supplying the rolled coil to the leveler with the unwound hot-rolled coil interposed therebetween. The thickness of the steel sheet to be passed is 1.0 to 5.5 mm, Is about 600 mm / min. By the spacer 8, the roll interval d when the sheet is not passed through is set to 0.5 mm (the minimum sheet thickness t).
By setting to about 50% of _min , the contact between the upper and lower rolls is completely prevented, and there is no problem such as insufficient rolling force even for steel sheets with the minimum thickness, and work can be performed stably for a long period of time. did it.

In the comparative example, when the spacer was not provided, the sprayed layer on the roll surface was peeled off by the contact between the upper and lower rolls, and the roll replacement cycle was within 6 months.
On the other hand, in this example, no peeling of the roll surface was observed. The roll replacement cycle was about 18 months, and the life was extended more than three times as compared with the comparative example.

[0025]

According to the present invention, when a cermet spray roll containing carbide is used in a pinch roll press-down apparatus, contact between upper and lower rolls can be prevented and the roll life can be greatly extended. Further, when the contact of the rolls is prevented, even when the diameter of the rolls is changed due to a roll exchange or the like, it has become possible to easily cope with the changes without a large facility modification.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a pinch roll rolling down device.

FIG. 2 is an explanatory diagram of a roll contact prevention method of the present invention.

FIG. 3 is a schematic view of a pinch roll rolling down device of the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lower roll 2 Upper roll 3 Rolling stand 4 Axis 5 Hydraulic cylinder 6 Steel plate 7a Lower chock 7b Upper chock 8 Spacer d Roll interval when not passing

Claims (1)

[Claims] When a cermet spraying roll containing carbide is used in a pinch roll reduction device for a steel sheet, spacers are arranged between upper and lower chocks at both ends of the roll, and a roll interval when the sheet is not passed is rolled by the reduction device. A roll contact preventing method, wherein the thickness is limited to a range of 20 to 60% of a minimum thickness of the steel sheet.