US3555862A - Apparatus for continuously rolling steel - Google Patents

Abstract

A CONTINUOUS STEEL ROLLING MILL APPARATUS. BETWEEN EACH PAIR OF A PLURALITY OF ROLLING MILLS ALONG THE ROLLING LINE IS PROVIDED AN ADJUSTING ROLLING MILL. A SMALL CAPACITY D.C. MOTOR IS COUPLED TO EACH ADJUSTING MILL AND SUPPLIES ONLY SUFFICIENT POWER TO THE ROLLS THEREOF TO OVERCOME THE INERTIA AND BEARING FRICTION. AN ADJUSTING DEVICE IS PROVIDED ON EACH ADJUSTING ROLLING MILL FOR ADJUSTING THE SCREW DOWN POSITION IN RESPONSE TO THE CONDITION OF THE MATERIAL BETWEEN THE ROLLING MILLS. THE ADJUSTING ROLLING MILL PERFORMS LIGHT LOAD ROLLING FOR CONTROLLING THE TENSION AND THE THRUST ACTING ON THE ROLLED MATERIAL SO THAT IT IS EITHER SMALL OR ZERO, THEREBY ELIMINATING BAD EFFECTS ON THE SECTION OF THE ROLLED MATERIAL. DETECTING MEANS CAN BE PROVIDED FOR DETECTING THE TENSION AND THRUST ON THE MATERIAL BETWEEN THE ROLLING MEANS, SUCH DETECTING MEANS BEING COUPLED TO THE ADJUSTING DEVICE FOR SETTING THE SCREW DOWN POSITION IN RESPONSE TO THE DETECTED CONDITION.

Description

. Jan. 19, 1971 YAMATA YOSHINO ETAL 3,555,862

APPARATUS FOR CONTINUOUSLY ROLLING STEEL Filed Jan. 24, 1969 FIG. I

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' K m w47z INVENTORS j Bwwflkzw ATTORNEYS United States Patent 3,555,862 APPARATUS FOR OUSLY ROLLING Yamata Yoshino, Kanichi Kishikawa, and Katsuyoshi Tanaka, Kitakyushu, Japan, assignors to Nippon Steel Corporation, Tokyo, Japan, a corporation of Japan Continuation-impart of application Ser. No. 554,447, June 1, 1966. This application Jan. 24, 1969, Ser. No. 814,869

Int. Cl. B21b 37/00 U.S. C]. 72-10 3 Claims ABSTRACT OF THE DISCLOSURE A continuous steel rolling mill apparatus. Between each pair of a plurality of rolling mills along the rolling line is provided an adjusting rolling mill. A small capacity DC. motor is coupled to each adjusting mill and supplies only suflicient power to the rolls thereof to overcome the inertia and bearing friction. An adjusting device is pro vided on each adjusting rolling mill for adjusting the screw down position in response to the condition of the material between the rolling mills. The adjusting rolling mill performs light load rolling for controlling the tension and the thrust acting on the rolled material so that it is either small or zero, thereby eliminating bad effects on the section of the rolled material. Detecting means can be provided for detecting the tension and thrust on the material between the rolling means, such detecting means being coupled to the adjusting device for setting the screw down position in response to the detected condition.

This application is a continuation-in-part of application Ser. No. 554,447, filed June 1, 1966, now abandoned.

This invention relates to an apparatus for continuously rolling steel, particularly large-sized cross-section steel shapes.

So far dilficulty has been encountered in continuously rolling steel, particularly with respect to large sized crosssection steel shapes, and continuous rolling has not yet been generally practiced except for steel billets.

In the continuous rolling of steel, it is desirable to equalize the delivery volume per unit time of the rolled material delivered from the rolls of each rolling mill; and in order to obtain a uniform shape of rolled products, it is best to keep the rolled material free from tension and compression when it is running between two rolling mills. However, in the conventional continuous rolling method, it is difiicult to equalize the delivery volume per unit time of the rolled material, because the rolling factors change during the operation. It is widely known that for comparatively thin sheet steel and also comparatively smalldiameter steel bar (including wire rod), the continuous rolling of these materials has been effected by intentionally forming a loop, and adjusting the number of rotations of the motors of the rolling mills. But large-sized materials cannot make a loop as does thin sheet and small bar, because they have a great moment of inertia of the cross section and will not bend or loop easily; and, moreover, ma terials having a section of complex shape tend to be deformed when subjected to bending into a loop, and also they sometimes are introduced to the induction apparatus at the inlet of the rolling mill, not in the normal course, but offset therefrom. Even in a rolling operation using compression in an amount which does not cause an enlargement of the steel material, the exclusive use of a rolling mill of the conventional type causes a great impact on the rolled materials when they are passed between rolls and also causes trouble between the rolls and the induction apparatus when an enlargement occurs. So tensionrolling has been generally used in place of the above type rolling. However, in tension-rolling, the cross-section of the rolled material tends to be contracted so that waving and contraction of the rolled material occurs in the longitudinal direction of the material.

As mentioned above, in the continuous rolling of largesized cross-section steel shapes, neither compression nor tension on the rolled material is desirable, but because unfinished steel rolled from a billet must subsequently be subjected to processes including a finishing rolling before it is a finished product, the continuous rolling is worthwhile in order to raise efficiency at the sacrifice of uniformity of product quality. However, for the above reasons, wholly continuous rolling of large-sized steel materials has been thought to be difficult, and therefore it has not yet been practiced.

On the other hand, in order to conduct non-load rolling which will not produce tension or thrust on the rolled material, there is available a method, according to which any force Working on the rolled material is detected and the rotation of the rolls is controlled in response to such detection. However, this method is impractical because it is unreliable in operation and in large scale equipment due to the inertia of rotation of the rolls which makes quick response impossible. As a result, a large capacity motor is required to allow for over-load operation in a short time and a large size rolling mill is necessary to Withstand the strong forces produced during operation.

Likewise the method of adjusting the screw down position of the rolling mill in response to the detection of forces working on the rolled material, which is conducted in the same way as mentioned above, is not practical for the reason that it necessitates altering the screw down position of all the rolling mills subsequent to the rolling mill in question.

As mentioned above, the continuous rolling of steel, particularly large-sized steel materials, has been thought to be highly eflicient, but has not yet been put into practice because of a number of difficulties.

For the purpose of solving these difficulties, it is an object of this invention to provide a continuous rolling apparatus which consists of a number of rolling mills set close to each other in the rolling direction, and therefore is generally considered to be a wholly continuous rolling apparatus, such apparatus making possible continuous rolling of large-sized cross-section steel shapes as well as large-sized steel billets or blooms without producing such strong tension or thrust that the section of the rolled material is affected and also without using any precise device for controlling the motors for the rolling mills.

Another object of this invention is to provide an adjusting rolling mill which can be set between each two rolling mill stands in the rolling apparatus consisting of a plural number of rolling mills, thereby making possible equalizing the delivery volume per unit time of the rolled material released from the rolls and controlling tension or thrust which would affect the section of said rolled material, such adjusting rolling mill being driven by a small motor and having an adjusting device for adjusting the screw down position thereof.

The invention will now be explained in greater detail in connection with the accompanying drawings, in which:

FIG. 1 is a plan view of the rolling apparatus according to this invention;

FIG. 2 is an enlarged sectional elevation of a part of the apparatus of FIG. 1 showing an example of a control circuit for adjusting for the elfects caused by thrust on the rolled material; and

FIG. 3 is a front elevation showing of the adjusting rolling mill of this invention having a pair of rolls driven by a small capacity D.C. motor.

According to the present invention, in a continuous steel rolling apparatus consisting of a plural number of rolling mills driven by large capacity motors for rolling mills, there is set between each two adjacent stands of the rolling mills adjusting rolling mills which are driven by a small capacity D.C. motor but are not given a rolling action at all, and which have an adjusting device for adjusting the screw down position. These adjusting rolling mills are small-sized rolling mills which are driven with only enough power sufficient to overcome the inertia of rotation of the rolls and the friction between the rolls and the bearing and with insufficient power for rolling. Each of the adjusting rolling mills is equipped with a pair of rolls of smaller size than the rolls of the rolling mill stands and also with a device for finely adjusting the screw down position. By driving these smaller size rolls just enough to overcome bearing friction and inertia, the effect of the impact of the steel being rolled on the smaller size roller will be substantially eliminated.

This invention relates to a continuous steel rolling apparatus which is characterized as above and which has means for detecting tension and thrust on the material being rolled between said rolling mills, and for setting the screw down position in response to such detection, thereby conducting light load rolling on the rolled material contrary to the tension and thrust, resulting in control of the tension and thrust working on the rolled material such that it is zero or so small that no bad effects will be produced on the cross-section of the rolled material.

The following is an explanation of this invention with reference to the attached drawing. In the drawing, 1, 2 and 3 are the rolling mills each having a pair of rolls driven for rolling the material to be rolled and which are driven by respective motors 5, 6 and 7 for the rolling mills which supply rolling power to the rolling mills 1, 2 and 3, respectively. Pinion stands 10, 11 and 12 are provided for the rolling mills 1, 2 and 3. The motors 5, 6 and 7 are synchronous motors for making the respective rolling conditions constant. Adjusting rolling mills 8 and 9 are positioned between adjacent rolling mills, each having a pair of small-sized rolls which are driven by a conventional small capacity D.C. motor, but not supplied with power for rolling. The small capacity DC. motors 13 and 14 supply a pair of the small- sized rolls 17 and 18 attached to the rolling mills 8 and 9 only with power sufiicient to overcome the inertia of rotation and the friction between the rolls and the bearings, but not with any substantial power for rolling. In practice they can be as small as 100 kw., depending on the size of the shape being rolled. Conventional D.C. speed control means can be used to control these motors.

On the other hand, the continuous rolling apparatus of the conventional type is composed only of the rolling mills which have their rolls supplied with power for rolling, similar to the rolling mills such as the adjusting rolling mills 8 and 9. In the drawing of this invention, 4 is the rolled material and the arrow points in the rolling direction. FIG. 2 shows the cross-section of the upper roller 15 and the lower roller 16 of the rolling mill 1 which are supplied with power for rolling and a cross-section of rolls 17 and 18 which are not supplied with power for rolling, and the cross-section of the upper and lower rolls 27 and 19 of the rolling mill. Adjusting devices 20 (FIG. 3) for setting the screw down position of the upper roll 17 in the rolling mill are connected to a motor 21 for setting the screw down position. The stand 22 for the rolling mill 8 has bearing boxes for the rolls 17 and 18. The rolling mill stand 22 is set firmly on a sole-plate 23 which is installed on the foundation.

In the operation of the above apparatus of this invention for rolling steel material 4 in the direction of the arrow, there is applied to the rolled material a strong force in the horizontal direction which is produced by the friction and rolling pressure between the upper roll 15 and the lower roll 16 respectively and the rolled material, which force working in the horizontal direction is utilized to cause said rolled material 4 to be rolled between the small- sized rolls 17 and 18 which are not provided with power for rolling. In other words, the light load rolling by the rolls 17 and 18 is such that the rolled material is not subject to impact caused by insertion and is thus not damaged thereby. By properly setting the reduction rates of the rolls 17 and 18 which are supplied only with power sufiicient to overcome the inertia of rotation and the friction of the bearings of the rolls and which are driven by the small capacity D.C. motor capable of nearly equalizing the speed at which the rolled material 4 is supplied and the circumferential speed of the rolls at nonload operation, the force working in the horizontal direction on the rolled material 4, and constituting the motion for rolling by said rolling mill, will not become stronger in proportion to the enlargement of the rolled materiol 4.

The load cells 24 and 24' are positioned beneath the the rolling mill 2 subsequent, in the direction of rolling, to the small-sized adjusting rolling mill 8. Because of tension and thrust produced on the rolled material 4, moment is produced centering around the lower port of said rolling mill 2, which is converted to electric current, which, in turn, is relayed to a value setter 25 to obtain the deviation, which is altered to a value for setting the screw down position through the converter 26 to be finally relayed to the small capacity D.C. motor for setting the screw down position by means of motor 21. This is a conventional technique.

Similarly, if tension exists between the rolling mills 1 and 2, the rolling mill 2 will lean to the left, making the load cell 24 start to work and changing the load to electric current, finally putting the motor for setting the screw down position 21 into operation to change the screm down position lower. Thus, the rolled material coming from the small-sized rolling mill 8 is made thinner and thus extended to be longer, so that the tension between the rolling mills 1 and 2 is reduced or eliminated.

As mentioned above, the continuous rolling apparatus of this invention has many great advantages. If this is used for rolling large shapes, it will produce many satisfactory results which could not be obtained otherwise.

We claim:

1. A continuous steel rolling mill apparatus for rolling large steel sections, which comprises a plurality of rolling mills spaced from each other along a line, an adjusting rolling mill at a fixed position between each pair of rolling mills, a small capacity D.C. motor coupled to each adjusting rolling mill supplying only sufficient power to the rolls thereof to overcome the inertia and bearing friction thereof, and an adjusting device on each adjusting rolling mill for adjusting the screw down position in response to longitudinal forces exerted by the material, whereby light load rolling is performed on the rolled material running between said rolling mills, and the tension and thrust acting on the rolled material is controlled so as to be nothing or so small that no waving or contraction will be produced on the section of the rolled material.

2. An apparatus as claimed in claim 1 wherein the adjusting rolling mill is a small-sized rolling mill consisting of a pair of rolls of smaller diameter than those of each of said rolling mills.

3. A continuous steel rolling mill apparatus as claimed in claim 1 further comprising detecting means for detecting the tension and thrust produced between said rolling mills and coupled to said adjusting device for setting the screw down position of said adjusting rolling mill in response to the condition detected.

1/1944 Shayne et al 72-234 3/ 1967 Motomatsu et a1. 72-21 MILTON S. MEHR, Primary Examiner U .8. Cl. X.R. 72234

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