KR100415639B1 - Method for bonding hot rolled strips - Google Patents

Abstract

PURPOSE: A method for bonding hot rolled strips is provided which not only performs bonding operation promptly, but also reduces length of bonding line. CONSTITUTION: In a method for bonding rough rolled steel sheets having thickness of t, the method for bonding hot rolled strips comprises the steps of overlapping tail end part of preceding strip and top end part of succeeding strip with each other; positioning an overlapped part of the strips between a pair of bonding rolls installed in such a way that the pair of bonding rolls are movable into a fixed type bonding machine housing, and a gap between the pair of bonding rolls is narrowed when the pair of bonding rolls are moved along a moving direction of the strips; and moving the pair of bonding rolls along a moving direction of the strips in the state that the overlapped part of the strips is pressed by the pair of bonding rolls, thereby bonding the overlapped part of the strips by pressing as gradually reducing thickness of the overlapped part of the strips, and controlling the pair of bonding rolls so that final thickness of a bonding part of the strips bonded is maintained to 0.90 t to 0.95 t.

Description

Joining method of hot rolled material

The present invention relates to a method of joining a hot rolled material, and more particularly, to join the rear part of the preceding plate and the leading end of the subsequent plate so that the roughly rolled sheet in the hot rolling process can be continuously rolled in the subsequent finishing rolling process. It is about how to.

In the hot rolling process, existing rolling equipment is producing a product having a desired plate thickness by batch rolling of a material material after rolling roughly one by one. In this method, it is difficult to uniformly roll the whole sheet, and the front and rear ends of the sheet are not rolled properly, and many defects are likely to be present. Therefore, these defects must be removed after rolling, and high-speed finishing rolling is difficult.

The endless rolling proposed to solve this problem improves the productivity of the process by about 20%, improves the error rate of the product and can produce the material without undergoing the cold rolling process. Because of its many advantages, it is in the spotlight as a breakthrough process.

1 is a schematic layout view of such a hot rolling line for continuous rolling,

Rolled sheet material having a thickness of about 30-5Omm passing through the roughing mill 11 is stored in the coil box 12, and the sheet material from the coil box 12 passes through a leveler 13 to produce a crop shear (crop shear) ( In 14), the trailing end of the preceding board and the trailing board are cut, and then the trailing end of the preceding board and the trailing board are joined at the splicer 16 and passed through the section cutting device 18 to the finishing mill 19. do.

In FIG. 1, reference numerals 15 and 17 denote bar sliding devices.

As shown in FIG. 1, in order to perform the continuous rolling process, after the rough rolling is finished in the hot rolling line, the materials should be bonded to each other. This bonding is not only that the plates are moving, but the temperature of the plates is high, and the joining time is The longer the length of the line for joining, the longer the length of the joining, and there are various limitations such as the joining part must have sufficient joining force such that plate break does not occur in the subsequent finishing rolling process.

Among the limiting factors, the length of the joining line is examined. After rough rolling, the material moves at a speed of up to about 1m per minute, so if the joining does not occur quickly, the length of the line is long. Assuming that it takes place, considering the pre- and post-treatment of the plate will require a line of about 100m.

In addition, because the plate is moving, all the bonding apparatuses proposed so far (JP-A 7-323305, 63-93408) have a structure that moves simultaneously with the plate, and the distance required is 70-80m. Even if the line is separate, many limitations are applied when retrofitting an existing hot-rolled line.

2 shows a bonding apparatus having a structure that moves with the plate.

As shown in FIG. 2, the steel sheet conveyed from the roughing mill is guided to the splicer 16 by the roller 27.

The splicer 16 includes a movable splice roll bogie 20, and a wheel cutter 23 mounted on the upper portion and removing the scales of the lower portion of the trailing portion of the preceding material and the upper portion of the front portion of the trailing material. It is comprised including the press 22 to press.

In the jointer 16, the lower part of the tail joint part of the preceding steel plate and the upper part of the tip joint part of the following steel plate are scaled off by the said wheel cutter 23, and the wheel cutter 23 returns and the clamps 21 and 24 simultaneously. By the preceding material is lowered, and then the preceding material and the trailing material are press-bonded by the press 22 and the gas burner 26 at the bottom.

In FIG. 2, reference numeral 25 denotes a movable cylinder.

During the joining process, both the leading plate and the trailing plate are in a moving state, and the trolley and the joining apparatuses at the top thereof move simultaneously in accordance with the moving speed.

Since the conventional method is bonded while moving at the same speed as the movement of the plate, the length of the line for joining is not only long, but also the joining time is long.

Accordingly, an object of the present invention is to provide a method of joining a hot rolled material, which is capable of shortening the length of a joining line as well as faster joining in view of the problems of the conventional method.

1 is a schematic layout view of a conventional hot rolling line for continuous rolling

Figure 2 (a) is a schematic diagram of a conventional bonding device

(b) is an enlarged view of the bonding apparatus in FIG.

3 is a schematic layout view of a hot rolling line for continuous rolling using the joining method according to the present invention;

4 is a schematic view of a bonding apparatus according to the present invention

Figure 5 is a side view schematically showing the junction

6 is a graph showing the effect of the reduction ratio on the breaking load of the joint

Explanation of symbols on major parts of drawing

11 ... roughing mill 12 ... coil box

13 ... leveller 14 ... crop shear

15,17 ... bar sliding device 16 ... splicer

18 ... single side cutting device 19 ... finishing mill

20 ... Bonding roll bogie 21,24 ... Clamp

22 ... Press 23 ... Wheel cutter

25 ... movable cylinder 26. . . Gas burner

27 ... roll 28 ... splice housing

29,29 '... Joining roll pair 30 ... Joining roll pair guide

According to the present invention, when joining the roughly rolled thickness t to each other, the leading plate and the trailing plate are overlapped by pressing the pair of joining rolls movably installed in the fixed joint housing after overlapping the trailing end of the preceding plate and the leading end of the trailing plate. It is related with the method of joining the hot rolled material to be bonded to each other but adjusted so that the final thickness of the joining portion of the plate joined in the fixed bonding machine is 0.90t ~ 0.95t.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

In the present invention, in the case of the conventional method, the bonding machine is fixed to the point that the length of the line is lengthened by moving together with the movement of the steel sheet, and the bonding machine is fixed, but the pressing roll pair installed in the bonding machine is moved only for a short distance. By completing the joining process, the joining time and the line distance required for joining were shortened.

According to the method of the present invention, as shown in FIG. 3, the plate rolled to a thickness of about 30-50 mm through the rough mill 11 is stored in the coil box 12, and the crop plate 14 from the coil box 14 is stored. ) Cut the trailing part of the preceding plate and the leading part of the following plate. After cutting the plate, the scale is removed from the bottom of the joining portion, that is, the top surface of the preceding material joining portion, and then proceeds to the joining machine 16 shown in FIG. 4.

The splicer 16 is fixed and guides the splice roll pairs 29 and 29 ', which are movably installed in the fixed splice housing 28 and the splice housing 28, and the splice roll pair 29. It consists of a bonding roll pair guide 30 which is made.

In the splicer 16, the plate is joined by a pair of rolls 29 and 29 'installed in the fixed splicer. If the thickness of the plate entering the splicer is t, the thickness of the plate is 2t in the state of overlapping the two plates. Therefore, the gap between the top and bottom rolls is designed to be 2t, and these rolls are gradually moved from the right end to the left end along the roll guide 30 (ie, moving along the moving direction of the sheet) in the splicer. It is designed to reduce the gap. At the left end of the joint, the roll gap is 0.90t-0.95t, and the thickness of the plate joint is almost the same as the thickness of the plate. The sheet is finally rolled by the finishing mill 19 to produce a product having a desired thickness.

In the configuration of the bonding machine according to the present invention, the bonding roll moves a short distance in the fixed housing 28, the length of which is up to about 5m, so that the maximum distance of about 20m compared to the distance of 15-25m for the bonding device in the conventional bonding device. The line length reduction effect is obtained.

On the other hand, the reason for adjusting the thickness of the junction portion to 0.90t-0.95t is as follows. The strength of the joint at the solid state of the plate is proportional to the reduction ratio. In other words, as the reduction ratio (thickness after joining / thickness before joining) increases, the joining strength (joint efficiency, joint strength / base material strength) increases.

In general, when preparing the joint, the end face is inclined to increase the contact area as shown in Fig. 5, so that when the final thickness of the joint exceeds 0.95t, the rolling reduction is small and the joint thickness is 0.90t. If it is below, the cross-sectional area of a joint becomes small, and there exists a high possibility that plate breaking will occur at the time of finishing rolling.

It is preferable to process the joint inclined at an angle of 30-60 °.

Thus, according to the method of the present invention, not only can the line length required for the joining be reduced (see FIG. 3), but also the joining strength is increased so that there is no fear of breakage of the plate during finishing rolling, which is a post-process.

Hereinafter, the present invention will be described in more detail with reference to Examples.

A rough carbon steel sheet 12mm thick and 50mm wide finished was joined by the method shown in FIG. 4 according to the method of the present invention. The bonded test pieces were tensilely tested and the results are shown in FIG. 6. The joint was machined at an angle of 30 ° to 60 °.

6 shows that the joint is processed at an angle of 45 °, when the final thickness of the joint is 0.90-0.95t, it can be seen that the breaking load is the highest.

The hot fracture load of the base material was about 300kg, and the load that does not cause plate break during subsequent rolling is more than 90% of the base material break load, and the final thickness is 0.90-0.95t of the original thickness, which satisfies this criterion. have. These results were the same in the range of 30 ° -60 °.

On the other hand, if the thickness of the joint after bonding is less than 0.90t or more than 0.95t it can be seen that the break load did not meet the criteria.

As described above, according to the present invention, not only can the line length required for joining be greatly reduced by moving the minimum distance using a fixed joint but also the plate breaking in the subsequent finishing rolling process by adjusting the final joint thickness to an appropriate range. This can be prevented.

Claims (2)

In the method of joining the plate material of rough rolling finished thickness t, After overlapping the trailing end of the preceding plate and the leading end of the trailing plate, the overlapping portion of the plate is positioned between the pairs of joining rolls which are movable in the fixed joint housing and narrow the gap therebetween when moved along the direction of movement of the plate. Thereafter, by moving the bonding roll pairs along the moving direction of the sheet while pressing the overlapped portions of the sheet, the final portion of the joined portion of the joined sheet is 0.90 ton by pressing while gradually reducing the thickness of the overlapped portion. Joining method of hot rolled material, characterized in that to be adjusted to -0.95t. The method of claim 1, wherein the bonding roll pair is moved at a distance of 5 m or less.