In rolling a section steel, and especially the H-shapes, the universal rolling mill in which a pair of upper and lower horizontal rolls and a pair of right and left vertical rolls are incorporated into the same stand is used in general.
FIG. 1 shows rolling of an H-shapes. An H-shapes 1 is rolled by using vertical rolls (upright rolls) 7, 7' and horizontal rolls 45, 45'. A flange width 101 of the H-shapes 1 can be varied freely in a range of a roll body length 106 of the vertical rolls 7, 7'. On the other hand, a web height 102 (h) is determined by h=W+2t.sub.1, where t.sub.1 is a flange thickness 103 and W is a roll body length 104 of the horizontal rolls 45, 45'. Therefore, by a set of horizontal rolls with a constant width, only a size of the web height can be selected.
As the H-shapes, there is so-called H-shapes with constant outer dimensions that has a constant web height (web outer width) h. The H-shapes with the constant outer dimensions includes H-shapes with various flange thicknesses for the same nominal dimensions. For example, if the nominal dimensions are the web height: 600 mm.times.the flange width: 200 mm, the flange thickness is in a range of 12 to 28 mm. Therefore, it is necessary to properly vary a rolling width 105 (W.sub.1) according to the flange thickness. To adapt to change in the rolling width of the rolls, it is necessary to frequently replace the rolls. By frequently replacing the rolls, productivity is degraded. A large number of man-hours are necessary for the replacement and it is necessary to possess a large number of rolls.
To solve the above problems, there are width-variable rolling rolls proposed in Japanese Patent Publication No. 7-102365. A sectional view of an essential portion of the upper width-variable rolling roll is shown in FIG. 2. A roll body 10 is divided into a driving-side roll body 10a and an operating-side roll body 10b. The driving-side roll body 10a and the operating-side roll body 10b move relatively to each other along a direction of roll shafts and can move closer to and away from each other. Through a hollow strong portion of an operating-side roll shaft 11b to which the operating-side roll body 10b is fixed, a driving-side roll shaft 11a to which the driving-side roll body 10a is fixed is inserted and fitted. One of both the roll shafts can be inserted into and withdrawn from the other in the roll shaft direction and both the roll shafts can rotate synchronously. The driving-side roll shaft 11a and the operating-side roll shaft 11b are supported respectively by a driving-side roll chock 3 and an operating-side roll chock 4 functioning as bearings. An operating-side slide block 19 rotation of which is restrained and which can slide only in the direction of the roll shafts is mounted through a thrust bearing 17 to an operating-side shaft end of the operating-side roll shaft 11b. On the other hand, a push-in shaft 20 is disposed to be adjacent to a driving-side shaft end of the operating-side roll shaft 11b and a driving-side slide block 24 is mounted through a thrust bearing 21 to the push-in shaft 20. A screw block 25 for synchronous rotation is fastened to the driving-side slide block 24. To the screw block 25, a screw 27 with a pitch P.sub.1 and a screw 28 with a pitch 2P.sub.1 which have the same thread direction as each other are provided. The screw 27 is screwed to a fixed screw block (fixed screw ring 26) rotation and movement of which are restrained. The screw 28 is screwed to the above operating-side slide block 19.
Torque is transmitted from the driving-side roll shaft 11a to the operating-side roll shaft 11b through a feather key 16, for example.
A claw ring 30 is fitted into a notch groove 29 at an end portion of the driving-side slide block 24. A speed reducer 31 and an electric motor 32 are connected to the claw ring 30. When the electric motor 32 operates, the screw block 25 rotates. Because the screw block 25 is screwed to the fixed screw ring 26, the screw block 25 moves in the roll shaft direction. Because the driving-side slide block 24 fastened to the screw block 25 and the push-in shaft 20 move synchronously, the driving-side roll shaft 11a can move toward a driving side in the roll shaft direction (in a direction shown by an arrow 110). However, because the push-in shaft 20 is in contact with the driving-side roll shaft 11a only through a spherical face 111, a push-in device is used separately to move the driving-side roll shaft 11a toward an operating side in the roll shaft direction (in a direction reverse to the direction of the arrow 110). On the other hand, the operating-side slide block 19 connected to the screw block 25 through the screw 28 cannot rotate and can slide only in the roll shaft direction. Therefore, the slide block 19 moves in the shaft direction in a reverse direction to movement of the screw block 25 due to rotation of the screw block 25. For example, when the screw block 25 moves toward the driving side by a distance corresponding to a pitch P.sub.1 of the screw 27, the operating-side slide block 19 moves toward the operating side by a distance corresponding to a pitch 2P.sub.1 of the screw 28, which results in movement of the operating-side roll body 10b by a distance corresponding to the pitch P.sub.1 toward the operating side. In other words, with a turn of the screw block 25, the respective driving-side and operating-side roll bodies 10a and 10b move by distances corresponding to P.sub.1 in the reverse directions to each other without changing centers of the rolls. Therefore, it is possible to freely change a rolling width 105 of the horizontal rolls without changing the roll centers.
Here, a seal 33 is a scale seal for preventing scales or water from entering a gap between the driving-side roll body 11a and the operating-side roll body 11b.
In other words, effects of the technique disclosed in Japanese Patent Publication No. 7-102365 are as follows.
a) A roll width can be varied on-line, by remote control, and arbitrarily.
b) Because the roll width can be varied such that the rolls are shifted rightward and leftward respectively by the same distance from the roll center, the technique can be easily applied to tandem mills.
c) Even if the rolls are worn, products with constant dimensions can be obtained by varying the width.
d) Products with different sizes can be produced without replacing the rolls.
FIG. 3 is an explanatory view of an essential portion of a universal rolling mill having the above width-variable rolling rolls. A reference numeral 1 designates H-shapes as material to be rolled, 2, 2' designate a width-variable rolling rolls, 3, 3' designate driving-side roll chocks, 4, 4' designate operating-side roll chocks, 5, 5' designate spindle couplings for connecting horizontal rolls to a driving device, 6, 6' respectively designate downstroking and upstroking screws, 7, 7' designate upright rolls (vertical rolls), 8, 8' designate upright roll chocks, and 9, 9' designate support boxes.
The support box 9 (and 9', similarly) has a structure divided into a support box 9a bolted to the operating-side roll chock 4 and a support box 9b joined to the support box 9a as shown in FIG. 2. The above rolling width varying device is incorporated into the support box. In the support box 9b, a rolling width varying driving portion (hereafter simply referred to as "a driving portion") such as the push-in shaft 20, the speed reducer 31, the electric motor 32, and the like of the rolling width changing device is housed.
A support box 9b is joined to a support box 9a by using a lock device 400 shown in FIG. 4. The lock device 400 is formed from a lock pin 40, a lock bar 41, a spring 42, and a lock cylinder 43. By releasing the lock device 400, the support boxes 9a and 9b are easily separated from each other at a joint face. Therefore, the rolling width changing device can be easily separated from and mounted to a roll main body.
In order to separate the driving portion in the support box 9b from the roll shaft, the electric motor 32 in FIG. 2 is operated to move the push-in shaft 20 and the screw block 25 in the direction reverse to the direction of the arrow. By this movement, the push-in shaft 20 moves away from the roll shaft end with which the push-in shaft 20 was in contact only through the spherical face 111 and screwing for connecting the screw block 25 to a member in the support box 9a by the screws 27 and 28 is released. As a result, the driving portion is separated from the roll shaft. To connect the driving portion to the roll shaft, the above operations may be carried out in reverse order.
As described above, the technique disclosed in Japanese Patent Publication No. 7-102365 also has the following effects.
e) Because the roll and the rolling width varying device can be separated from and mounted to each other in a short time, the number of width adjusting devices may be decreased as compared with the number of the rolls.
However, depending on a type of the universal rolling mill, the following problems occur in replacement of the rolls.
FIG. 5 shows a front view of a universal rolling mill in which horizontal rolls have a constant width. A reference numeral 2' designates the horizontal roll with the constant width and others are similar to those in FIG. 3.
In general, the universal rolling mill receives rolling reaction force of the upright rolls 7, 7'. Therefore, rolling is carried out while pressing the upright roll chocks 8, 8' from outside by using reaction force receiving members called yokes 50. In replacement of the rolls, on the other hand, the yoke 50 on the operating side is caused to recede to keep working space. In this case, it is preferable to withdraw a roll set including the horizontal rolls 2, 2' and the upright rolls 7, 7' from the housing into the working space at a time and then to mount a new roll set for shortening the time required for replacement.
FIG. 6 shows a front view of a universal rolling mill in which the horizontal rolls have a variable width. A reference numeral 2 designates a horizontal roll with the variable width and others are similar to those in FIG. 3.
When the universal rolling mill is of a type in which the yoke 50 is caused to recede in a horizontal direction (rightward in FIG. 6 or in a direction perpendicular to a paper face), there is no problem. However, in the universal rolling mill of a type in which the yoke 50 is caused to recede upward, the yoke 50 interferes with the above support box 9 and therefore, the yoke 50 cannot recede. As a result, the roll set cannot be replaced at a time and the replacement of the rolls is time-consuming to extremely degrade efficiency.
On the other hand, in recent years, to improve accuracy of dimensions of the H-shapes or for systematic control, there is a tendency to dispose a plurality of universal rolling mills close to each other. For effectively utilizing a building, a place to put the products in is adjacent to the rolling mills in some cases. Therefore, it is difficult to keep space in the front and rear and on the right and left sides in the rolling direction of the universal rolling mill.