RU2260487C2 - Rod and wire product continuous rolling method and apparatus for performing the same - Google Patents

Abstract

FIELD: manufacture of rod and wire products in continuous rolling mills.

SUBSTANCE: in continuous rolling mill separate blanks are rolled in several stands to successive pieces of product having front and rear ends. First rolling stand operates at feed rate exceeding receiving rate of next second rolling stand. According to invention successive pieces of product leaving first rolling stand are directed from rolling line to welding station and from welding station back to rolling line for going on rolling process in second rolling stand. Front and rear ends of successive pieces of product are welded together in welding station. Apparatus for performing the process includes first and second rolling stands, welding station. The last is arranged aside relative to rolling line. Rolling mill is provided with unit for holding rolled pieces and unit for accumulating rolled pieces, both are placed in front and behind welding station.

EFFECT: lowered energy consumption, improved quality of products, minimum metal losses.

11 cl, 4 dwg

Description

FIELD OF THE INVENTION

This invention relates generally to the production of bar and wire products in continuous rolling mills by hot rolling of individual billets through the draft, intermediate and finishing sections of the rolling mill and, in particular, to a method and apparatus for welding end to end of individual pieces of products in a selected place on rolling lines with the possibility of continuous rolling without interruptions in the rest of the rolling mill.

State of the art

In conventional bar and wire rolling mills currently in operation, it is customary to start the process by heating individual billets in a furnace and then unloading them for separate rolling into product sections having a reduced cross-sectional area and front and rear ends. This practice has many disadvantages. For example, the time interval between blanks can be up to 10% of the loss of working time.

In addition, the front and rear ends of each segment of the product are unacceptable in size and / or metallurgical and therefore are cut off and discarded, resulting in significant scrap losses. The front ends are also prone to under-harmonica, in particular at high speeds achieved in the finishing section of the rolling mill.

In order to eliminate these problems, a technology was developed for welding end-to-end workpieces before being introduced into the rolling mill. However, it was also problematic. Welding workpieces with a large cross-section requires massive equipment and high energy costs. An extremely large amount of electrical energy is additionally required for induction reheating of the sections of the workpiece, which are cooled by contact with the heavy gripping devices necessary to force the ends of the workpieces together.

Another disadvantage of welding billets is that the molten metal at the weld site is then rolled into a substantial length of the finished product. For example, when workpieces having a typical cross-sectional area of 22,500 mm ² are welded and then rolled into a bar with a diameter of 5.5 mm, the molten weld metal passes through approximately 94 m of the finished product. If the workpieces are metallurgically not the same, then this length can go to scrap, which means large losses for the operator of the rolling mill.

According to this invention, welding technology is used in the rolling process in such a way and at such a place on the rolling line in order to eliminate or at least significantly minimize the problems and disadvantages inherent in the prior art.

According to the invention, the continuous rolling method is that individual billets are rolled in a mill through a plurality of rolling stands located along the rolling line to create successive product sections having reduced cross-sectional areas, while successive product sections have front and rear ends, the method includes connecting the rear end of the first segment of the product with the front end of the next second segment of the product and contains the stages:

operating the first of the rolling stands with a feed rate that exceeds the receiving speed of the next second rolling stand;

the direction of the first and second sections of the product when they exit the first rolling stand with a deviation from the rolling line along the inlet path leading to the welding section, and along the supply path leading back to the rolling line from the welding section, to continue rolling in the second rolling stand;

temporary accumulation of the first part of the first segment of the product on the supply path while rolling the first segment of the product in the second rolling stand;

holding the rear end of the first section of the product in the welding section for a time interval in which rolling of the accumulated first part in the second rolling mill continues;

holding the front end of the second segment of the product in the welding section for a specified time interval while simultaneously accumulating the second part of the second segment of the product along the inlet path;

welding the held front and rear ends to each other during a specified time interval; and

liberation of ends so welded.

Preferably, the welded ends are stripped before rolling in a second rolling stand.

It is advisable to re-heat the product sections before rolling in the second rolling stand.

The front and rear ends can be stopped during welding in the welding section.

These product sections have a cross-sectional area in the range from about 700 to about 4400 mm ² .

According to the invention, a rolling mill, in which individual billets are rolled into successive product sections having front and rear ends, includes a device for connecting the rear end of the first segment of the product with the front end of the next second segment of the product and contains:

the first and second rolling stands arranged sequentially along the rolling line, wherein the first rolling stand operates at a feed rate that exceeds the receiving speed of the second rolling stand;

guiding means for guiding the first and second sections of the product exiting the first rolling stand, deviating from the rolling line along the inlet path leading to the welding section, and along the supply path leading back to the rolling line from the welding section to the second rolling stand;

first accumulating means for temporarily accumulating the first part of the first section of the product along the supply path during rolling in the second rolling stand;

holding means for holding the rear end of the first segment of the product and the front end of the second segment of the product in the welding section for a period of time in which rolling of the accumulated first part of the first segment of the product in the second rolling mill continues;

second accumulating means for temporarily accumulating the second part of the second segment of the product along the input path during the specified time interval; and

welding means in said welding section for welding the front and rear ends held together with each other, after which the first and second sections of the product are continuously rolled in the second rolling stand by releasing the front and rear ends so welded.

Preferably, the holding means is arranged to stop the front and rear ends in said welding section.

The rolling mill may further comprise means along said supply path for stripping the welded front and rear ends of said first and second product sections.

Also, the rolling mill may further comprise means for reheating said sections of the article before said second rolling stand.

It is advisable that the storage device contains a stand of the loop group of the mill for the accumulation of the specified first part in the form of a loop.

Preferably, the stopping means comprises blocks of drive pressure rollers on the inlet and outlet sides of said welding section.

List of drawings

The drawings show:

figure 1 - embodiment of a device according to this invention in a top view;

figa-2J - successive stages of operation of the device shown in figure 1;

figure 3 is an alternative embodiment of the device according to this invention in a top view;

figure 4 is a section along the line 4-4 in figure 3, illustrating the stacking capacity of the drive, on an enlarged scale.

Information confirming the possibility of carrying out the invention

As shown in FIG. 1, the first and second vertical and horizontal rolling stands 10 and 12 are located along the rolling line P. The rolling stand 10 may comprise, for example, the last rolling stand of the rough section of the rolling mill, and the stand 12 may comprise a first rolling stand of the intermediate section of the rolling mill. The feedrate of the rolling stand 10 exceeds the receiving speed of the rolling stand 12. Thus, when, for example, a rolling mill rolling a workpiece weighing 2000 kg at a speed of 150 tons per hour, the rolling stand 10 will produce a bar having a cross-sectional area of 57.4 mm at a feed rate of 2052.5 mm / s. The receiving speed of the rolling stand 12 will be 1642 mm / s.

Switches 11 are provided for guiding successive pieces of product leaving the rolling stand 10 from the rolling line P and to the input path 14 leading to the welding section 16, and from the welding section along the feeding path 15 back to the rolling line for continuous rolling in the rolling stand 12 and in all subsequent rolling stands (not shown). Alternatively, the switches 11 can be controlled to bypass the input path 14 and to ensure further passage of individual sections of the product along the rolling line P.

The first storage means in the form of a stand 18 of the loop group of the mill is located along the path 15 of the feed, and the second storage means in the form of a stand 20 of the loop group of the mill is located along the inlet path 14. The stands 18, 20 of the loop group of the mill have a conventional construction well known to those skilled in the art areas of technology.

The welding section 16 includes a welding device 22, configured to weld the joined rear and front ends of the product sections. Welding points are cleaned with a stripper 24 before continuing along the feed path 15. Welding spots and adjacent sections of the product can, if necessary, be reheated in front of the rolling stand 12 using an induction heater 26. The drive pressure rollers 28, 30, 32 and 34 are arranged to control the forward movement of the processed product sections.

The following is a description of the operation of the device with reference to figa-2J.

Figure 2A

The first section And the product is rolled through a rolling stand 10 with a flow rate of 150 tons per hour and at a speed of 2052.5 mm / s. The section A of the product passes along the inlet path 14, through the welding section 16 and along the feed path 15, and its front end A _FE comes to the pressure roller unit 34, where it temporarily stops. The first part of the first section of the product begins to accumulate in the form of a loop A _L in the stand 18 of the loop group of the mill.

Figure 2B

The loop A _L in the stand 18 of the loop group of the mill has grown significantly, and the front end A _{FE of the} first section of the product passed through the block 34 of pressure rollers into the rolling stand 12. The rolling speed of the rolling stand 12 is 120 tons per hour with a receiving speed of 1642 mm / s.

Figure 2C

Loop _AL in stand 18 of the loop group of the mill reached its maximum. The rear end A _{TE of the} first piece of product just exits the rolling stand 10, and the front end B _{FE of the} second piece B of the product approaches the rolling stand 10.

2D figure

The rear end A _{TE of the} first section A of the article moves to the inlet path 14 when the front end B _{FE of the} second section B of the article enters the rolling stand 10.

Figure 2E

The rear end A _{TE of the} first section A of the article and the front end B _{FE of the} second section B of the article reached the welding section 16, where they are held motionless in contact with each other using blocks 32, 30 of the pressure rollers. Welding of the front and rear ends begins.

Figure 2F

While welding the front and rear ends, the loop A _{L of the} first section of the product in the stand 18 of the loop group of the mill is gradually reduced, and the second section B of the product is accumulated in the form of a loop B _L in the stand 20 of the loop group of the mill.

2G figure

The welded front and rear ends emerged from the welding section 16 into the rolling stand 12, and the loop B _L , previously accumulated in the stand 20 of the loop group of the mill, is transferred using blocks 30, 32 of the pressure rollers to the stand 18 of the loop group of the mill.

Figure 2H

In the process of transferring the loop B _L from the stand 20 of the loop group of the mill to the stand 18 of the loop group of the mill, the rear end B _{TE of the} second section of the article reaches the rolling stand 10.

Figure 2I

As indicated above with reference to FIG. 2D, the rear end B _{TE of the} second product section now moves to the input path 14 when the front end C _{FE of the} third product section C enters the rolling stand 10.

Figure 2J

Welding of the rear end B _{TE of the} second section of the article with the front end C _{FE of the} third section of the article has begun, as described above with respect to FIG.

Blocks 28, 30, 32 and 34 of the pressure rollers are driven separately and therefore, it is possible to selectively control the acceleration, deceleration and stop of successive sections of the product in order to influence the above movements. Although welding is preferably performed when the front and rear ends are stopped at section 14, as an alternative solution, the pressure roller units 30, 32 can simply slow down the front and rear ends, while the welding device 22 is movable to perform welding in motion.

After the front product is fed into the rolling stand 12, the interrupted rolling then continues in that stand and in the following stands in the rest of the rolling mill.

Welding the front and rear ends with a reduced cross-sectional area in section 16 can be performed quickly, with minimal energy consumption and with the help of small, less expensive welding equipment.

FIGS. 3 and 4 show an alternative embodiment of the invention in which components identical to those of the embodiment shown in FIG. 1 are denoted by the same reference numbers. In this case, the stand 20 of the loop group of the mill of the first embodiment is replaced by a multilevel drive 40.

As shown in FIG. 4, the drive comprises vertically stacked pairs of guide rollers 42 located around the annular contour 44. The guide rollers form a helical feed path 46 having a configuration and dimensions that provide storage capacity of the product comparable to the capacity of the stand 20 of the loop group of the mill shown in figure 1 of the embodiment.

In view of the foregoing, it will be understood by those skilled in the art that the present invention provides for the deviation of successive product sections exiting the rolling stand 10 from the rolling line P and the direction along the inlet paths 14 (or 46) to the welding section 16, and from of the welding section along the supply path 15 back to the rolling line for subsequent rolling in the rolling stand 12. The stand 18 of the loop group of the mill operates in conjunction with blocks 32 and 34 of pressure rollers on the exit side of the welding section for temporary storage the first accumulated segment of the product and to stop or slow down the rear end of this segment of the product in the welding section.

The stand 20 (or accumulator 40) works in conjunction with the pressure roller blocks 28 and 30 on the inlet side of the welding section to stop or slow down the front end of the next section of the product in the welding section and to temporarily store the second accumulated section of the product.

The accumulation of the first and second segments of the product provides sufficient time for welding stopped or slowed down the rear and front ends in the welding section. Thus, in the rolling stand 12 is fed a continuous product formed from individual pieces of the product received from the rolling stand 10.

The present invention is most preferably used for joining product sections having a reduced cross-sectional area in the range of from about 700 to about 4400 mm ² . In this case, the molten metal of the weld points extends over a relatively short length of about 3-18 meters. Thus, even when pieces of workpieces having different metallurgical parameters are welded, scrap losses are minimized compared with the losses that occur when welding workpieces before rolling.

Claims (11)

1. A method of continuous rolling, in which individual billets are rolled in a mill through a plurality of rolling stands located along the rolling line to create successive product sections having reduced cross-sectional areas, while successive product sections have front and rear ends, including a rear end connection the first section of the product with the front end of the next second segment of the product, the operation of the first of the rolling stands with a feed rate that exceeds the receiving speed next the second rolling stand, the direction of the first and second sections of the product when they exit the first rolling stand with a deviation from the rolling line along the inlet path leading to the welding section, and along the supply path leading back to the rolling line from the welding section, to continue rolling into the second rolling stands, temporary accumulation of the first part of the first section of the product on the supply path while rolling the first section of the product in the second rolling stand, holding the rear end of the first section of the product in the welding section during the time interval in which rolling of the accumulated first part in the second rolling stand continues, holding the front end of the second section of the product in the welding section for the specified time while accumulating the second part of the second section of the product along the inlet path, welding the front and back ends with each other during the specified time interval and the release of the ends thus welded. 2. The method according to claim 1, in which the welded ends are subjected to stripping before rolling in a second rolling stand. 3. The method according to any one of claims 1 or 2, in which the product sections are reheated before rolling in a second rolling stand. 4. The method according to claim 1, wherein said front and rear ends are stopped during welding in the welding section. 5. The method according to claim 1, in which these sections of the product have a cross-sectional area in the range from about 700 to about 4400 mm ² . 6. A rolling mill, in which individual billets are rolled into successive sections of the product having front and rear ends, comprising a device for connecting the rear end of the first segment of the product with the front end of the next second segment of the product, the first and second rolling stands located sequentially along the rolling line, wherein the first rolling stand operates at a feed rate that exceeds the receiving speed of the second rolling stand, guiding means for guiding the first and second segments the line leaving the first rolling stand, with a deviation from the rolling line along the inlet path leading to the welding section, and along the supply path leading back to the rolling line from the welding section, into the second rolling stand, the first storage means for temporarily accumulating the first part of the first piece of product along the feed path during rolling in the second rolling stand, holding means for holding the rear end of the first piece of product and the front end of the second piece of product in the welding section during the time interval during which the rolling of the accumulated first part of the first section of the product in the second rolling stand continues, the second storage means for temporarily accumulating the second part of the second section of the product along the inlet path during the specified time interval and the welding means in the specified welding section for welding the front and the rear ends with each other, after which, due to the release of the front and rear ends so welded, continuous rolling of the first and W cerned segments products in the second roll stand. 7. The rolling mill according to claim 6, in which the specified holding means is made with the possibility of stopping the front and rear ends in the specified welding section. 8. The rolling mill according to claim 6, further comprising means along said supply path for stripping the welded front and rear ends of said first and second lengths of the article. 9. A rolling mill according to any one of claims 6 or 7, further comprising means for reheating said sections of the article before said second rolling stand. 10. The rolling mill according to claim 6, wherein said storage means comprises a stand of a loop group of a mill for accumulating said first part in the form of a loop. 11. The rolling mill according to claim 6, in which the specified stopping means contains blocks of drive pressure rollers on the sides of the input and output of the specified welding section.

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