RU2262399C1 - Method for making small hot rolled section and apparatus for performing the same - Google Patents

Abstract

FIELD: rolled products.

SUBSTANCE: method comprises steps of hot rolling, pointing leading end of rolled piece and drawing it. According to invention pointing and drawing are realized just after leading end of rolled piece leaves rolling stand at temperature of rolling process termination. Pointing is performed without reversing rolled piece in round roll grooved pass with the same diameter along circle of pointing rolls along length exceeding radius of drawing drum. In outlet pass of rolling stand oval cross section of rolled piece is formed; small axis of said oval is less than diameter of grooved pass of pointing head. Pointed end of rolled piece is fed into drawing plate at rotation of pointing rolls during pointing process. Apparatus for performing the method includes rolling stand with rolls and drawing unit. Rolls of rolling stand have row of grooved passes along length of their barrels. One roll has cantilever. Drawing unit includes drawing drum, drawing plate holder and pointing head. Drawing drum is rigidly secured to cantilever of roll. Drawing plate holder and pointing head are mounted in housing of rolling stand. Pointing head is in the form of two rolls; one roll is mounted with possibility of radial motion. Both rolls of pointing head form round pass of the same diameter along circle of rolls. Outlet roll grooved pass of rolling stand is in the form of oval whose small axis is less than diameter of pass of pointing head.

EFFECT: enlarged allowance value for wear of roll grooved passes of finish stand of rolling mill.

4 cl, 3 dwg, 1 ex

Description

The invention relates to the field of rolling production and can be used in the manufacture of low-grade hot-rolled profiles, for example wire rod.

A known method of manufacturing small-sized hot-rolled profiles by rolling and a device for its implementation, comprising a rolling stand with rolls having a number of calibers along the length of the barrel (see SU 129605, 10.10.1960).

The disadvantage of these technical solutions is the low accuracy of the cross section of the resulting profile. In addition, ensuring the accuracy of the cross-section of the profile requires frequent replacement of the rolls of the finishing stands, which increases the downtime of the rolling mill and the cost of its repair.

Closest to the claimed method is a method of manufacturing a fine-grained hot-rolled profiles, including hot rolling, sharpening of the front end of the rental and its drawing (see SU 1752466 A1, 08/07/1992).

Closest to the claimed device is a device for the manufacture of low-grade hot-rolled profiles containing a rolling stand with rolls and drawing block (see SU 1752466 A1, 08/07/1992).

When drawing is achieved, the accuracy of the wire section is an order of magnitude higher than the accuracy of the wire rod, however, the rolling and drawing processes are separated in the known method and device in time and place. In this case, the wire rod made at the rolling mill must be annealed before drawing (due to loss of ductility during cooling), transported to drawing equipment, and the loading and unloading operations of the latter.

The technical result to which the claimed invention is directed is to increase the accuracy of manufactured profiles, increase efficiency and reduce production costs by eliminating equipment for annealing and transporting workpieces, loading and driving mechanisms for drawing equipment, as well as by expanding the tolerance range for wear of calibers finishing stand of the rolling mill.

In a method for manufacturing small-sized rolling profiles, including hot rolling, sharpening of the front end of the rolled product and drawing it, in accordance with the invention, sharpening and drawing is carried out at the temperature of the end of rolling immediately after the front end of the rolled product leaves the rolling stand, sharpening is performed without reverse rolling, in a round caliber of the same diameter along the circumference of the sharp rolls, for the length of the rental exceeding the radius of the drawing drum, while in the output gauge of the rolling stand I give the rental t oval cross-section, the small axis of which is smaller than the diameter of the gauge of the pointed head, and the supply of the pointed end of the car into the die is carried out by rotating the sharp rolls during the sharpening process.

, определяемый из выражения:

In addition, before introducing into the die, a periodic rotation of the rolled product (its cross section) by an angle is possible

defined from the expression:

where b is the size of the minor axis of the oval rolling section;

d is the working diameter of the die.

The claimed method, due to the ability to maximally bring time and distance closer, the processes of hot rolling and drawing, practically combining them (the product is both in the rolling stand and in the draw), eliminates the operation of annealing, transportation of wire rod to drawing equipment and its loading, which leads to reduce production costs. In addition, due to the fact that the drawing is carried out deliberately at high temperature, using rolling heating, the metal has increased ductility, which allows to increase the degree of compression in the die, to increase the accuracy of the resulting profile. This circumstance allows to increase the allowance for drawing, which, in turn, makes it possible to significantly - several times - expand the tolerance for wear of the gauges of the finishing stand, thereby reducing the downtime of the rolling mill and the cost of repairing it.

Performing the sharpening operation in a sharp gauge with a diameter equal to the circumference of the rolls makes it possible to sharpen (thin) the end of the rolled product directly during its movement, without rolling reversal.This circumstance allows the thinned end of the workpiece to be inserted into the fiber and then to the drawing drum by the force of rotation of the sharp rolls. The length of the rolled section subjected to sharpening (thinning) must exceed the radius of the drawing drum, which ensures reliable capture and fixation of the front end of the rental in the drum.

The rolling at the exit of the rolling stand with a cross section in the form of an oval, the small axis of which is smaller than the diameter of the gauge of the head provides favorable conditions for the capture and deformation of the rolled in the sharp rolls.

Periodic rotation of the cross section of the rolled metal before introducing it into the die is used to align the wear of the die along its perimeter, while the angle of rotation, regulated by the mathematical dependence

where b is the size of the minor axis of the oval of the rolling section d is the working diameter of the die, ensures the optimum alignment process.

In the device for manufacturing small-sized hot-rolled profiles containing a rolling stand with rolls and a drawing block, in accordance with the invention, a number of calibers along the length of the barrels are made on the stand rolls, one of the rolls is made with a console, the drawing block consists of a drawing drum, a fiber holder with a wire and a sharp heads, while the drawing drum is rigidly fixed to the roll stand of the rolling stand, the fiber holder and the head are mounted on the stand frame, the head is made in the form of two rolls, about Institute of which is mounted for radial movement, forming the same caliber round along the circumference of roll diameter, and the output gauge stand is configured in the form of an oval, the minor axis smaller than the diameter of the head ostrilnoy caliber.

In addition, the rolls of the rolling stand can be kinematically coupled with the rolls of the point of the head with the possibility of ensuring their rotation.

The claimed device allows a drawing operation to be carried out simultaneously with rolling, and rolling - with maximum reductions, while the manufacturing process of the products is carried out practically without heat loss through the use of one finishing stand with several calibers located in the technological sequence combined with drawing equipment. The above design features provide for the use of a rotation drum for transmitting rotation and, as a special case, to the rolls of the sharp head, the drive of the rolling stand, for which the said elements are kinematically connected to each other. So, for example, the rolls of the rolling stand can be connected with the rolls of the point of the head of the chain transmission. Thanks to the kinematic relationships indicated above, the drum and the spindle rolls are constantly rotating and ready to go, and the sharpening process is simplified by opening or closing the spike gauge, which is easy to automate.

Performing a sharp gauge with the same diameter along the circumference of the rolls makes it possible to sharpen (thin) the end of the rolled product directly in the process of its movement, without reverse, which is inevitable when using traditional pointed heads with a constant axial distance between the rolls, which form a smaller cross-section in pairs when the rolls turn.

This circumstance allows you to enter the thinned end of the workpiece into the die and then to the drawing drum by the force of rotation of the sharp rolls.

In this case, the required length of the thinned end of the workpiece is provided by opening the pointed gauge by radial movement of one of the pointed rolls when the end is gripped by a drawing drum. This design solution allows you to get the thinned end of the workpiece of sufficient length to fix it directly on the drawing drum without the use of chain devices with grippers.

The execution of the output gauge of the rolling stand in the form of an oval, the small axis of which is smaller than the diameter of the pointed gauge, provides a reliable grip of the end of the rolled rolls of the sharp head and a favorable deformation pattern in these rolls.

The claimed device allows to exclude manual operations when sharpening the end of the rental and entering it into the draw and drawing drum, automate these processes, eliminate the chain gripper, as well as equipment for heat treatment and transportation of workpieces in the area between rolling and drawing. Due to the fact that the front end of the rental immediately after it leaves the last gauge of the finishing stand is introduced into the draw of the drawing device, the maximum reduction in the time interval between rolling and drawing, and therefore the loss of temperature and plastic properties of the rental, is achieved. This allows you to increase the degree of compression of the metal in the die, to increase the accuracy of the resulting profile and thereby expand the tolerance for wear of the output gauge of the finishing mill stand, which leads to a reduction in downtime of the rolling mill and the cost of its repair.

The invention is illustrated by drawings, which depict:

figure 1 is a front view of a rolling stand with a drawing device;

figure 2 is a left view of it;

figure 3 is a section aa along the shafts of the sharphead on an enlarged scale.

A device for the manufacture of small-sized hot-rolled rolling profiles contains (see Figs. 1, 2, 3) a finishing rolling stand, in the frame 1 of which rolls 2, 3 are installed, forming a number of calibers. The output caliber 4 is made in the form of an oval. The roll 3 is made cantilevered, has a free end on which the drawing drum 5 is rigidly fixed. A fiber holder 6 with a wire 7 and a pointed head 8 with sharp rolls 9 and 10 are fixed on the frame 1. The rolls 9 and 10 form a round-shaped pointed gauge 11, the diameter of which smaller than the working diameter of the die 7. The roller bearings 9 are mounted directly in the head housing 8, and the roller bearings 10 are located in an eccentric bore of the sleeve 12, which can rotate around its axis in the head housing 8 from a drive (not shown). With this rotation, at some angle, the roll 10 moves away from the roll 9, which leads to the disclosure of the sharp gauge 11. When turning in the opposite direction, the roll 10 approaches the roll 9, closing the sharp gauge 11.

The size of the minor axis of the oval of the output gauge 4 is smaller than the diameter of the pointed gauge 11.

The acrylic rolls 9, 10 are connected to the roll 3 of the stand, for example, by a chain gear 13 including sprockets 14, 15, 16, 17, and the sprocket 16 serves to obtain the necessary direction of rotation of the rolls 9, 10.

The manufacturing process consists of the following steps. The billet of a wire rod (ingot or forging) is heated to the temperature of the start of rolling and is repeatedly deformed in the crimp, semi-finishing and finishing stands of the rolling mill. Immediately after the front end of the rolling stock exits from the output gauge of the finishing stand, it is introduced into the spike head where it is thinned and fed through the die hole to the drawing drum.

Then the sharpening is stopped and drawing is carried out to a predetermined size simultaneously with rolling the rest of the workpiece in the mill stands. Thanks to the drawing, the accuracy of the obtained profile is increased several times in comparison with the accuracy of the wire rod.

Due to the fact that drawing is carried out at high temperature, the metal has increased ductility. This eliminates the operation of annealing the wire rod before drawing, as well as transportation and loading of drawing equipment.

In addition, the increased ductility makes it possible to increase the degree of compression of the metal in the die, which expands the tolerance for wear of the output gauge of the finishing stand, and therefore, reduces the downtime of the mill and the cost of repairing it.

The operation of the device is as follows.

The heated billet is fed into the crimping stand of the rolling mill (not shown in FIG.), Then it enters the finishing stands (not shown) and into the rolls 2, 3 of the finishing stand.

The rollers 2, 3 rotate, the drawing drum 5 rotates with them and, through the chain drive 13, the sharp rolls 9, 10, which are brought together to form a closed sharp gauge 11.

When the front end of the rolled product leaves oval gauge 4, it is turned over by the circumferential groove (not shown) by the small axis of the oval horizontally and is fed by the rolling force into the sharp gauge 11 of head 8. Due to the small axis of the oval, the gauge has a size smaller than the diameter of the pointed gauge 11, rotating rolls 9, 10 capture the end of the rolled product and deform it into a circular section, the diameter of which is less than the diameter of the hole of the die 7, producing the necessary thinning.

Under the action of the rolling force of the sharp rolls 9, 10, the thinned end of the rolling passes into the working hole of the die 7 and then to the drawing drum 5. At this moment, the eccentric sleeve 12 rotates in the head housing 8, which leads to the movement of the sharp roll 10 from the roll 9, opening pointed caliber 11 and the termination of the process of sharpening (thinning) of the rental. At the same time, the thinned end of the hire is fixed by a clamp (not shown) in the rotating drawing drum 5 and the process of drawing the rolling process begins, which from this moment proceeds simultaneously with the rolling of the remaining part of the workpiece and ends after the last exit from the die.

An example embodiment of the invention.

The process of manufacturing a wire of diameter 8 from an alloy of the brand X20H80 (nichrome) with high electrical resistance is as follows.

The billet (casting) is heated in the furnace to the temperature of the start of rolling - 1240 ° C and served in the crimping stand of the linear fine mill and then to the finishing and finishing stands of the linear group.

Rolling is carried out at a speed of 2.5 ÷ 3 m / s. It is known from experience that with a normal ingot mass of 70 ÷ 80 kg and a specified rolling speed, the rolling process lasts 100 ÷ 120 s, and the metal temperature drops to 950 ÷ 900 ° C during this time.

Immediately after the front end of the rolled product leaves the last gauge of the finishing stand, it is fed to the spike head, then through the calibrated hole of the die it enters the drawing drum and goes through the drawing process. From the moment a rolled product leaves the finishing stand to the start of drawing, it takes only 3–5 seconds, during which time it cools down to 850–800 ° С.

The relative elongation of the X20H80 alloy at a temperature of 800 ° C is 70.1% (for comparison, at 20 ° C, in the annealed state - 45.4%). This allows you to increase the degree of compression in the die up to 36% compared with 15 ÷ 18% recommended for this alloy during cold drawing.

In our example, this means that the diameter of the circle, equal in area to the output oval gauge of the finishing stand, is 10 mm, and the drawing allowance is 2 mm.

In these 2 mm, the error of adjusting the finishing stand rolls, their elastic deformations and wear of the output gauge should fit.

In the manufacture of wire rod with a diameter of 8 mm without drawing, its tolerances are ± 0.3 mm, as a result of which the tolerance for wear of the output gauge should be less than 0.6 mm.

Thus, the proposed invention allows in this case to expand the tolerance for wear of the caliber more than 3 times, and therefore, proportionally reduce the downtime of the mill for repair and the cost of the latter.

The accuracy of the obtained profile will be, as usual, when drawn to the specified size ± 0.045 mm, which is 6.5 times higher than rolled.

The operations of annealing, transportation and loading of drawing equipment with special mechanisms are excluded, the cost of production is significantly reduced.

Claims (4)

1. A method of manufacturing small-section hot-rolled profiles, including hot rolling, sharpening of the front end of the rolling and drawing, characterized in that the sharpening and drawing is carried out at the temperature of the end of rolling immediately after the front end of the rolled from the rolling stand, sharpening is performed without reverse rolling in a round caliber of the same diameter along the circumference of the rolls of rolled steel for a length greater than the radius of the drawing drum, while in the output gauge of the rolling stand, the oval is rolled Noe cross-section minor axis smaller than the diameter gauge ostrilnoy head and feeding the tip end rolled into a die by rotating the process rolls in ostrilnyh ostreniya. 2. The method according to claim 1, characterized in that prior to being fed into the die, the rolling is periodically rotated by an angle

defined from the expression

where b is the size of the minor axis of the oval rolling section; d is the working diameter of the die. 3. A device for the manufacture of small-section hot-rolled profiles containing a rolling stand with rolls and a drawing unit, characterized in that a number of calibers along the barrel length are made on the stand rolls, one of the rolls is made with a console, the drawing unit consists of a drawing drum, a fiber holder with a wire and a sharp head, while the drawing drum is rigidly fixed to the roll stand of the rolling stand, the fiber holder and the sharp head are mounted on the stand bed, the sharp head is made in the form of two rolls, one of which oryh mounted for radial movement, forming the same caliber round along the circumference of roll diameter, and the output gauge stand is configured in the form of an oval, the minor axis smaller than the diameter of the head ostrilnoy caliber. 4. The device according to claim 3, characterized in that the rolls of the rolling stand are kinematically connected with the rolls of the head with the possibility of ensuring their rotation.

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