JP2003080313A - Method for coiling ultra thick steel plate and mandrel for coiling strip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent slips between a coil and a mandrel by improving tight contact with the mandrel by controlling the shape of the tip part of a steel plate in a coiling stage of the hot-rolled strip of an ultra thick steel plate. SOLUTION: By increasing the outer diameter of the mandrel 3 for coiling the strip before three inner turns of the steel plate is coiled with the mandrel 3 in the initial stage of the coiling of a ultra thick hot-rolled steel plate 1, gaps generated between the layers of the strips and between the strip and the mandrel are squeezed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for winding an extremely thick steel plate in a hot rolling process and a strip winding mandrel used for carrying out this method.

[0002]

BACKGROUND OF THE INVENTION The recent boom in oil and natural gas pipelines has increased the need for linepipes. 20-30mm plate thickness for line pipe material
Extra thick hot rolled steel sheet is mainly used. Even in such an extremely thick hot-rolled steel sheet, in order to smoothly handle it in the pipe forming process, it is essential to wind it into a coiler to form a coil.

Generally, the state of winding a hot rolled steel sheet is shown in FIGS.
This is as shown in FIG. The tip of the rolled steel plate 1 is
After passing through the finish rolling machine and passing over the runout table, as shown in FIGS. 1 and 2, the pinch roll 2 arranged in front of the winding device guides the traveling direction downward. Further, as shown in FIG. 3, the tip of the steel plate 1 has a # 1 trumpet roll 4, an arc-shaped guide apron 5 and a mandrel 3 as shown in FIG.
4 is sequentially plastically bent by the three-point support state of the mandrel 3 as shown in FIG.
Wrap around. Thereafter, a continuous strip is wound into a coil to form a hot rolled coil.

In such a winding mode, a non-plastic region remains at the tip of the steel sheet 1. In the case of winding with an ordinary coiler, the non-plastic region is a straight line portion of about 200 to 300 mm between the support points of the guide apron 5 and the mandrel 3. Here, the non-plastic region, even if forced deformation,
It is an area that tries to return to its original shape as soon as the force is removed. Therefore, a bent shape is likely to occur at the boundary between the non-plastic region and the steel sheet 1 thereafter. This is one of the factors that hinder the adhesion between the steel plate 1 and the mandrel 3.

Generally, in a thick material having a plate thickness of more than 20 mm, the material rigidity becomes high, so that the above-mentioned tendency of bending is likely to be remarkable. As a result, the contact ratio between the mandrel and the steel plate is reduced, and the slip phenomenon frequently occurs. When slip occurs, the coil winding shape deteriorates. Sometimes it becomes impossible to wind and the mill stops. In order to prevent slippage in such thick materials, the following techniques have been conventionally proposed.

As disclosed in Japanese Patent Application Laid-Open No. Sho 49-120853, a control method in which a mandrel motor is controlled to surely wind a steel plate from the beginning and to smoothly wind the steel plate without a gap.

In order to eliminate the non-plastic region at the most distal end of the material, a plastic bend is applied to the tip end of the pinch roll located immediately before the mandrel to improve the adhesion to the mandrel.

[0008]

However, each of the above conventional methods has the following problems.

The boundary waist bend between the non-plastic and plastic regions at the tip of the material remains as a void between the strips. Further, it is necessary to microscopically monitor and control the process of winding the material around the mandrel, but this monitoring technique is not sufficient.

The upper and lower pinch rolls have different diameters and their center positions are offset with respect to the line advancing direction, so that the strips are supported at two points. In order to give plastic bending to the tip, it is necessary to support the upper surface of the entry strip and form a three-point support state. However, considering the structure of the coiler, it is practically impossible to install this input side support device.

That is, conventionally, it has not been possible to prevent the slip between the coil and the mandrel by controlling the shape of the tip of the strip to improve the close contact with the mandrel. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a technique that does not cause a waist break when winding an extremely thick steel plate.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and as a technical means thereof, suppresses the formation of voids between the strips or between the strip and the mandrel as in the prior art. Instead of this, we propose a technique to prevent the coil and mandrel from slipping by crushing the formed void. That is, the present invention is a method for winding an extremely thick steel plate, characterized in that, in a winding process of a hot-rolled strip, voids generated between the strip layers and between the strip and the mandrel are crushed at the initial stage of winding. Further, in this case, it is preferable that the means for crushing the gap is performed by winding up three turns of the inner winding, and as a concrete means for crushing the gap, the inner diameter of the strip coil is increased. Good. Further, as a means for increasing the strip coil inner diameter, it is preferable to increase the outer diameter of the strip winding mandrel.

Next, a strip winding mandrel of which the outer diameter is continuously increased is provided as an apparatus of the present invention capable of suitably carrying out the above method. Further, the mandrel includes a shaft having a plurality of tapered portions, a slide rod slidingly in contact with the tapered portions, a segment fixed to the slide rod, and a moving mechanism for moving the strip winding. It should be a mandrel for taking. Further, a strip winding mandrel using a rotary cylinder as the moving mechanism is preferable.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention effectively utilizes the two-stage expansion / contraction function of a mandrel, which is conventionally known as a mechanism for preventing slip flaws from the surface layer of a mandrel that occurs in the inner winding of a steel sheet when winding a thin material. Is. The two-stage expansion / contraction function of the mandrel is a technique that has been used to secure an appropriate winding tension. Based on this basic function, the method of the present invention has been realized by developing a mandrel expansion / contraction mechanism that secures sufficient thrust for crushing the voids between the layers of the winding material and makes the stroke variable. is there. However, the method of the present invention is not limited to the above-mentioned means for enlarging the inner diameter of the coil by enlarging the mandrel diameter, as long as the means can crush the gap. In addition, it is essential to crush the voids in the initial stage of coil winding, and it is more effective to crush the voids by the time of winding three turns of the inner winding.

Embodiments of the present invention will be described below with reference to the drawings. An example of the mandrel according to the present invention will be described based on the structural diagram of the mandrel 3 shown in FIG. Mandrel 3
The internal structure of is the same as that of the conventional two-stage expansion / contraction type, but its main purpose is to prevent slippage, and thrust and stroke design necessary and necessary to crush the gaps between the materials are important. The mandrel 3 is provided with a segment 12 which is divided into a plurality of circumferences to form an expandable and retractable winding drum. The slide rod 11 is attached to the inner diameter side of the segment 12. The tapered portion 14 of the shaft 13 is in contact with the slide rod 11. Shaft 13
A rotary cylinder 15 is provided as a moving device for axially shifting. The rotary cylinder 15 is attached to the distributor 16. The rotary cylinder 15 includes a position detector. The shaft 13 is shifted by the operation of the rotary cylinder 15, the segments of the mandrel 3 are moved in the radial direction, and the diameter of the mandrel 3 is expanded or contracted. If the expansion diameter is limited to two steps, the over-expansion stroke becomes constant, and the expansion cylinder does not function effectively with the winding material having a large gap. Therefore, the rotary cylinder 15 as the expansion / contraction drive source is a stepless type. Further, a sensor (position detector) for detecting the stroke of the rotary cylinder 15 is provided so that the standby diameter of the mandrel 3 before winding can be arbitrarily set. However, in this case, the diameter of the mandrel 3 at the time of standby is not necessarily a perfect circle, so that the edge portion of the segment 12 is devised so as not to project.

<Example> An example of the method of the present invention will be described below. A hot rolled steel sheet having a plate thickness of 20 mm was subjected to a 100 coil winding test under the following conditions to investigate the slip occurrence rate. a) It was wound with the mandrel diameter fixed. In such a conventional technique, the slip occurrence rate was 10%. b) The expansion stroke was set to 30 mm, the diameter of the mandrel was expanded, and the expansion was completed after 5 rounds of inner winding. In this example, the slip occurrence rate was 1%. c) The expansion stroke was set to 30 mm, the diameter of the mandrel was expanded, and the expansion was completed after three rounds of inner winding. In this example, the slip occurrence rate was 0%. d) The expansion stroke was set to 60 mm, the mandrel diameter was expanded, and the expansion was completed after 5 rounds of inner winding. In this example, the slip occurrence rate was 0%.

As is clear from the above results of the slip occurrence rate, the slip occurrence could be suppressed by the method of the present invention.

[0018]

EFFECTS OF THE INVENTION According to the present invention, in a hot rolled thick material, slip between the strip inner winding and the mandrel surface layer is eradicated, proper winding is possible from beginning to end, and downtime due to winding mistake is eliminated. .

[Brief description of drawings]

FIG. 1 is an explanatory view showing a steel plate winding step.

FIG. 2 is an explanatory diagram showing a steel plate winding step.

FIG. 3 is an explanatory view showing a steel plate winding step.

FIG. 4 is an explanatory view showing a steel plate winding step.

FIG. 5 is a sectional view showing a mandrel structure of an example.

[Explanation of symbols]

1 steel plate 2 pinch rolls 3 Mandrel 4 trumpet roll 5 guide aprons 11 Slide rod 12 segments 13 Mandrel shaft 14 taper 15 Rotary cylinder (including position detector) 16 distributors

Claims (7)

[Claims] 1. A method for winding an extremely thick steel sheet, characterized in that, in the winding step of a hot-rolled strip, voids generated between the layers of the strip and between the strip and the mandrel are crushed at the initial stage of winding. 2. The winding method for an extra-thick steel plate according to claim 1, wherein the means for crushing the voids is carried out before winding three turns of inner winding. 3. The strip coil inner diameter is increased as a means for crushing the gap.
The method for winding the extremely thick steel sheet described. 4. The winding method for an extremely thick steel plate according to claim 3, wherein the means for increasing the inner diameter of the strip coil is to increase the outer diameter of the strip winding mandrel. 5. A strip winding mandrel comprising a mechanism for continuously increasing the outer diameter. 6. A shaft having a plurality of tapered portions, a slide rod slidably contacting the tapered portions, a segment fixed to the slide rod, and a moving mechanism for moving the shaft. The mandrel for winding the strip according to claim 5. 7. The strip winding mandrel according to claim 6, wherein the moving mechanism is a rotary cylinder.