SU1176981A1 - Method of hot rolling of strips - Google Patents

Abstract

Method of hot strip rolling, including rough rolling, turning, cutting front and back. Rolled ends and finishing rolling, characterized in that, in order to reduce metal losses during cutting, the roll turning is carried out lia 180 after half of roughing passages at even number and after less than half of roughing passages at odd number. (/)

Description

, R7.7 /, / 2, 2f / e-b1 The invention relates to oSpaSotic metals by pressure and can be used in the production of hot rolled strips on strip-strip and plate mills in ferrous and non-ferrous metallurgy. The aim of the invention is to reduce the loss of metal in the cut. The essence of the method lies in the fact that the roll of the roll is realized by 180 after half of the rough passes with even their number. And after less than half of the rough passes with odd number of them. This allows a significant reduction in metal losses due to cutting due to the fact that in the process of hot rolling strips when metal is seized by rolls, the work rolls experience elastic torsion. The greatest angle of the specified torsion of work rolls is from the side of their drive, the smallest zero. - in cross section of rolls,., located on the edge of the strip from the side of transshipment. As a result of the marked non-identical elastic torsion of working rolls across the width of the roll, when metal is gripped, the longitudinal sections of the metal, located closer to the drive side, of the rolls, are more heavily compared to the similar sections of the gauge metal, located close to the side of the transshipment rolls. At the end of the deformation of the strip strip rolling, the pattern of unequal stretching is repeated across the width of the roll and its cause in this case becomes the elastic unloading of the work rolls. The variation of stretching is not the same for a single roughing pass, as it passes, it accumulates and ultimately leads to asymmetrical in terms of the shape of the front and rear ends of the roll with elongated tongues from the drive side of the rolls. The presence of the latter when trimming the front and rear ends of the rolled strip before the finishing rolling significantly increases the loss that you need. The drawing shows the layout of the equipment for the production of the proposed method on a wide band mill. The equipment includes a roughing group of stands 1-6 finishing group 812 of stands 7-13, scissors 14, a device 15 for tilting an intermediate roll by 180., a harvesting group 16, A device for tilting an intermediate roll to 180 is located between the roughing stands, The stands before and after the specified device can differ by no more than one stand. The initial billet (slab) 17 in the deformation process goes through rough rolling stages, which includes intermediate rolls 18-22 and tackle 23, and finishing rolling is completed. strips 24, process is performed as follows. The heated slab (FIG. 1) is first rolled into roughing cages x 1-6, reducing its thickness {1 to thickness 23, After the thickness of the intermediate sheet becomes half equal to the thickness difference between the original billet 17 and the rolled 23 or a little more than this value, the roll is turned by 180 by the device 15. With an even number of roughing passes from workpiece 17 to rolled 23, the intermediate roll is edged after half the passes, with odd - less than half the number of roughing passes. ernovyh passageways before and after the intermediate tilting of roll 180 may differ by no more than one, and the latter to a certain extent also dependent on the number of mill stands in the roughing mill which implement pre-Laga method. As applied to hot rolling of strips on a plate mill, the turning of the intermediate roll by 180 is also carried out after the realization of half of the smaller number of half of the roughing passes. If this condition is violated, firstly, the effect of reducing the loss of metal into the cut will be reduced, and secondly, there may be difficulties with turning over a relatively thin intermediate roll of increased length. After kantovka 180 intermediate roll 20 (.Fig. 1) carry out its further rough rolling in the cages 4-6 with getting rolled 23, Sharpen 14 cut off the front and rear ends of rolled 23 and realized

are its final rolling in the cages 7-13 with obtaining the finished strip 24, which, when rolled on a wide-belt mill, is transported, wound into a roll using the cleaning group 16.

Due to the 180 ° tipping of the intermediate roll 20, the unevenness of stretching across the width of its front and rear ends, which was formed upon receipt of rolls 18-20, is gradually eliminated when receiving rolls 2122 and roll 23. As a result, the front and rear ends are formed on roll 23 with almost the same stretch width. The last significantly reduce the loss of metal in the cut when cutting the front and rear ends of the rolled with scissors 14.

Since the productivity of rough rolling is usually significantly higher than the productivity of finishing rolling, the introduction of an additional operation of turning the intermediate roll on I80 does not reduce the productivity of the rolling process as a whole.

Example. At the hot rolling mill strip of 1,700, from a slab of 175x1100x9500 mm, hot rolled strips with a thickness of 5 mm were rolled. Chernova mill group contains a vertical pit breaker, a horizontal descaler, a four-roll stand 1 and four-roll uniery four-roll stands 2-5, a flying knife is installed in front of the finishing group

769814

nitsy and it contains seven four-roll stands.

Rough rolling is performed in six passes in the following mode:

S 175-142-111-87,5-64-44-35,5 mm. After the third pass, the intermediate roll 87.5 mm thick is turned 180 ° and the remaining three passes are made. The front and rear ends of the 35.5 mm thick rolled strip are cut with scissors, after which finishing rolling is carried out onto a finished strip with a thickness of 5.0 mm, which is transported and wound into a roll. With the initial rectangular slab shape, after the first three roughing passes, the intermediate roll at the front and rear ends receives a significantly larger stretch from the drive side compared to the side of the rolls. Due to the indicated turning of the intermediate roll at 180 in the next three roughing passes, the undesirable further development of uneven stretching across the width of the front and rear ends of the rolls is suspended and ultimately get rolled with a practically uniform stretching at its ends.

I

The use of the edging of the intermediate roll by 180 ° after the third of the six rough passes allows a cut value to be reduced by more than 2 times.

Claims (1)

METHOD FOR HOT ROLLING OF THE STRIP, including rough rolling, tilting, cutting of the front and rear ends of the tack and finishing rolling, characterized in that, in order to reduce metal loss to trim, the tilting of the roll is carried out 180 after half rough passes with an even number and after less from half of draft passes with an odd number of them. Ml YpnA * 4 05 ς ©> 1 1176981