Deformed steel bar production tail end negative error rate improving method

Abstract

The invention discloses a deformed steel bar production tail end negative error rate improving method. The method comprises the following steps that 1, the position of the deformed steel bar tail end in production is monitored in real time; 2, when current and torque signals that the tail end of the deformed steel bar leaves a rolling mill of a specified sortie are monitored, a rolling mill of the last but one sortie and a rolling mill of the last but one sortie are subjected to speed reduction at the same time after specified time is delayed; and 3, when current and torque signals generated when the tail end of the deformed steel bar leaves the last but one rolling mill and the last but one rolling mill are monitored, the rotating speed of the last but one rolling mill and the rotating speed of the last but one rolling mill are sequentially recovered to the speed before speed reduction. Reasonable machining of the deformed steel bar can be achieved through a relatively simple control program, the problems that the head, middle and tail negative difference is large, and the negative difference is difficult to control are effectively solved, the negative difference between the rear half-length and the first half-length can be reduced, and the machining precision is improved. Therefore, the purpose of improving the negative difference of the whole deformed steel bar under the condition that the negative difference of the first double-length is not influenced is achieved.

Description

Technical Field

[0001] The invention belongs to the field of threaded steel production, and specifically relates to a method for improving the negative difference rate at the tail end of threaded steel production. Background Art

[0002] Rebar is the most common steel material in construction at present. It has been widely used due to its excellent performance. The disadvantages of the multi-line slitting process layout for rolling rebar are: there are often no loops between the rolling lines and the spacing between the lines is too large. During normal rolling, the lines are tension rolled, which causes the tail end of the rebar to be too large and the distance between the most parts to be too long. There may be problems such as the tail longitudinal rib size exceeding the upper limit and unqualified, and the negative difference is too small. The main competitive advantages of rebar production are output and cost. Therefore, in the production process, the method of increasing the amount of waste cutting at the tail end of the rebar has to be adopted to ensure the product is qualified. At the same time, the small negative difference at the tail seriously affects the product yield and product performance uniformity, which seriously affects the economic benefits and product quality. Summary of the invention

[0003] The invention provides a method for improving the negative difference rate at the tail end of threaded steel production, so as to solve the defects in the prior art.

[0004] The present invention is achieved through the following technical solutions:

[0005] A method for improving the negative difference rate at the tail end of rebar production comprises the following steps:

[0006] Step 1: Real-time monitoring of the end position of the rebar in production;

[0007] Step 2: When the current and torque signals of the tail end of the rebar leaving the specified rolling mill are monitored, the third to last rolling mill and the second to last rolling mill are simultaneously slowed down after a specified delay to reduce the phenomenon of the tail end of the rebar being too large;

[0008] Step 3: When the current and torque signals of the tail end of the rebar leaving the third-to-last rolling mill and the second-to-last rolling mill are monitored, the rotation speeds of the third-to-last rolling mill and the second-to-last rolling mill are restored to the speeds before the speed reduction in turn.

[0009] As described above, a method for improving the negative difference rate at the tail end of rebar production, the designated rolling mill is the penultimate or second to last rolling mill of intermediate rolling. At present, the rebar rolling process is generally divided into three processes: rough rolling, intermediate rolling and finishing rolling. Delaying and reducing the speed when the tail end of the rebar leaves the intermediate rolling and is about to enter the finishing rolling can effectively reduce the negative difference rate at the tail end of the rebar.

[0010] In the method for improving the negative difference rate at the tail end of rebar production as described above, the specified delay time is 0-1000ms.

[0011] In the method for improving the negative difference rate at the tail end of rebar production as described above, the roller diameters of the third-to-last rolling mill and the second-to-last rolling mill are 330-380 mm.

[0012] As described above, a method for improving the negative difference rate at the tail end of rebar production, the speed of the third-to-last rolling mill reduced = the set value of the speed reduction per second × (the time from the tail end of the rebar leaving the designated rolling mill to the tail end of the rebar leaving the third-to-last rolling mill - the specified delay time).

[0013] As described above, a method for improving the negative difference rate at the tail end of rebar production, the speed of the second-to-last rolling mill reduced = the set value of the speed reduction per second × (the time from the tail end of the rebar leaving the specified rolling mill to the tail end of the rebar leaving the second-to-last rolling mill - the specified delay time).

[0014] In the above-mentioned method for improving the negative difference rate at the tail end of threaded steel production, the speed reduction revolutions per second setting value is 0.1-0.5r / s.

[0015] The advantages of the present invention are: in the present invention, the deceleration speed of the second-to-last rolling mill is less than the deceleration speed of the third-to-last rolling mill and the speed is linearly reduced over time, so that part of the rolling of the steel billet is in the deceleration rolling during the operation, and the negative difference between the head, the middle and the tail and the root difference are further reduced; at the same time, reasonable processing of rebar can be achieved through a relatively simple control program, and the problem of large negative difference between the head, the middle and the tail and difficult control of the negative difference is effectively solved. The present invention can reduce the negative difference between the last half length and the first length, so as to improve the negative difference of the whole rebar without affecting the negative difference of the first length; and the present invention can be remotely monitored and controlled through the main station room, so as to realize truly automated control, improve the convenience of operation, and improve the efficiency of rebar production to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 Schematic diagram of delayed speed reduction adjustment of Example 1 of the present invention (where K3 is the third to last rolling mill, and K2 is the second to last rolling mill);

[0018] Figure 21 is a schematic diagram comparing the longitudinal rib dimensions of threaded steel bars before and after the delayed speed reduction procedure is used in Example 1 of the present invention (the left figure is after use, and the right figure is before use);

[0019] Figure 3 1 is a schematic diagram comparing the negative difference rate of rebar before and after using the delayed speed reduction procedure in Example 1 of the present invention;

[0020] Figure 4 Schematic diagram of delayed speed reduction adjustment of Example 2 of the present invention (where K3 is the third to last rolling mill, and K2 is the second to last rolling mill);

[0021] Figure 5 1. This is a schematic diagram comparing the longitudinal rib dimensions of threaded steel bars before and after the delayed speed reduction procedure is used in Example 2 of the present invention (the left figure is after use, and the right figure is before use);

[0022] Figure 6 It is a schematic diagram comparing the negative difference rate of rebar before and after using the delayed speed reduction program in Example 2 of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Example 1 takes φ25 large-size threaded steel as an example:

[0025] The production line includes 1 to 6 rough rolling stands, 7 to 8 intermediate rolling stands, and 13 to 18 finishing rolling stands.

[0026] According to the diameter requirement of φ25 rebar, a delay time of 10ms is input in the rolling mill control system in advance (it can be adjusted according to the rolling conditions). When the tail of the billet completely leaves the 8th rolling mill, the rolling mill control system obtains the relevant torque signal and after a delay of 10ms, the 17th rolling mill slows down by 0.2r / s, and the 16th rolling mill slows down by 0.4r / s (such as Figure 1 As shown), the speed reduction time is 21s, and finally the minimum speed of the 17th rolling mill is 627r / s, and the minimum speed of the 16th rolling mill is 694r / s. The speed reduction starts at 124m of the whole rebar, and the speed reduction length is 200m (the length of the whole rebar is 324m), so that the part of the billet in the 16th and 17th rolling mills is in the speed reduction rolling, reducing the size of the steel bar (such as Figure 2As shown in the figure, the longitudinal rib size is 29.2mm before the delayed speed reduction program is used; the longitudinal rib size is 26.2mm after the delayed speed reduction program is used); through the above operation and control of the steel rolling system, the tail end of the rebar can be automatically decelerated to reduce the large gap between the head, middle and tail negative differences and the problem of difficult control of negative differences. The negative difference rate before and after use is increased by 0.11%, -2.34% before commissioning, and -2.45% after commissioning (such as Figure 3 shown).

[0027] Example 2 takes φ12 small-size threaded steel as an example:

[0028] The production line includes the 1st to 6th rough rolling stands, the 7th to 11th intermediate rolling stands, the 14th to 19th finishing rolling mills. K2 is the 18th rolling mill and K3 is the 17th rolling mill.

[0029] According to the diameter requirement of φ12 rebar, a delay time of 1000ms is input in the mill control system in advance (it can be adjusted according to the rolling conditions). When the tail of the billet completely leaves the 11th mill, the mill control system obtains the relevant torque signal and after a delay of 1000ms, the 18th mill slows down by 0.3r / s, and the 17th mill slows down by 0.4r / s (such as Figure 4 As shown in the figure, the lowest speed of the 18th rolling mill is 573r / s, and the lowest speed of the 17th rolling mill is 723r / s. The speed reduction starts at 329m of the whole rebar, and the speed reduction length is 247m (the whole rebar length is 576m), so that the part of the billet in the 17th and 18th rolling mills is rolled at a reduced speed, reducing the size of the steel bar (as shown in the figure). Figure 5 As shown in the figure, the rib size before the delayed speed reduction program is 14.9 mm, and the longitudinal rib size after the delayed speed reduction program is 13.9 mm); through the above-mentioned operation and control of the steel rolling system, the tail end of the rebar can be automatically decelerated to reduce the large gap between the head, middle and tail negative differences and the difficulty in controlling the negative difference. The negative difference rate before and after commissioning increased by 0.10%, 3.82% before commissioning, and 3.92% after commissioning (as shown in the figure). Figure 6 shown).

[0030] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for improving the negative difference rate at the tail end of rebar production, characterized in that: The steps include: Step 1: Real-time monitoring of the end position of the rebar in production; Step 2: When the current and torque signals of the tail end of the rebar leaving the specified rolling mill are monitored, the third to last rolling mill and the second to last rolling mill are simultaneously slowed down after a specified delay to reduce the phenomenon of small negative difference at the tail of the rebar; Step 3: When the current and torque signals of the tail end of the rebar leaving the third-to-last rolling mill and the second-to-last rolling mill are monitored, the rotation speeds of the third-to-last rolling mill and the second-to-last rolling mill are restored to the speeds before the speed reduction in turn.

2. A method for improving the negative difference rate at the tail end of threaded steel production according to claim 1, characterized in that: The designated rolling mill is the penultimate or second to last rolling mill of the intermediate rolling mill.

3. A method for improving the negative difference rate at the tail end of threaded steel production according to claim 1, characterized in that: The delay specified time is 0-1000ms.

4. A method for improving the negative difference rate at the tail end of threaded steel production according to claim 1, characterized in that: The roll diameters of the third-to-last rolling mill and the second-to-last rolling mill are 330-380 mm.

5. The method for improving the negative difference rate at the tail end of threaded steel production according to claim 1, characterized in that: The speed of the third-to-last rolling mill reduced = the set value of the speed reduction per second × (the time from the tail end of the rebar leaving the designated rolling mill to the tail end of the rebar leaving the third-to-last rolling mill - the specified delay time); The rotation speed reduced by the second-to-last rolling mill = the set value of the speed reduction revolutions per second × (the time from the tail end of the rebar leaving the designated rolling mill to the tail end of the rebar leaving the second-to-last rolling mill - the specified delay time).

6. A method for improving the negative difference rate at the tail end of threaded steel production according to claim 1, characterized in that: The speed reduction revolutions per second setting value is 0.1-0.5r / s.

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