A production line and process method for solving the low performance of the non-cooling section of the high wire head

Abstract

The application discloses a production line and a process method for solving the low performance of a high wire head non-cooling section, which comprises a heating furnace, rough and medium rolling, pre-precision rolling, precision rolling, reducing sizing, a pinch roll wire spitting machine, an air cooling line and a temperature control water tank, the heating furnace is connected with the rough and medium rolling, the rough and medium rolling is connected with the pre-precision rolling, the pre-precision rolling is connected with the precision rolling, the precision rolling is connected with the reducing sizing, the reducing sizing is connected with the pinch roll wire spitting machine, the pinch roll wire spitting machine is connected with the air cooling line, and the air cooling line is connected with the temperature control water tank; the heating time is effectively shortened to 2-3 hours by canceling the preheating section heating, the steel tapping temperature is reduced to 900-950 DEG C, the finished product temperature after finishing rolling is reduced to 750-800 DEG C, the non-cooling section length is accurately controlled to be within 10 turns, the 1# air box is reformed to form a mixed strengthening process of air cooling and mist cooling, the cooling intensity on both sides of the coil is reinforced, the high wire head non-cooling section performance is improved by 30-40 MPa through the above measures, the grain size is improved by one level, the national standard requirement is reached, the head cutting is cancelled, the material yield and the energy utilization rate are improved, and remarkable benefits are created for enterprises.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel processing, in particular to a production line and process method for solving the low performance of the head non-cooling section of high-speed wire. BACKGROUND

[0002] Due to the characteristics of high speed and small specification, the finished product after finishing rolling must be clamped by the front pinch roll of the wire drawing machine before being opened and then passing through the water control temperature. If it is opened after finishing rolling, the rolling piece will shake due to the large water pressure, causing the steel pile accident. Therefore, the high-speed wire production must have a certain length of head non-cooling section. The purpose of temperature control after rolling is to slow down the grain growth rate by reducing the temperature of the rolling piece, thereby playing a role in refining the grain strength performance.

[0003] The head non-cooling section of the high-speed wire has high steel temperature and large grain size, resulting in lower performance of the head than the standard requirement. Moreover, the length of the head non-cooling section is not easy to accurately judge, and most enterprises adopt the method of cutting off 20-30 turns of the head to solve this problem. This method greatly reduces the high-speed wire yield and causes waste. Moreover, the incomplete cutting of the head flows into the market, which has quality risks.

[0004] The existing application is to accurately measure the length of the non-cooling section, accurately measure and cut the length of the head non-cooling section to reduce waste, and does not fundamentally solve the problem of low performance of the head. Therefore, a production line and process method for solving the low performance of the head non-cooling section of high-speed wire are needed to solve the technical problem. SUMMARY

[0005] The purpose of the present application is to provide a production line and process method for solving the low performance of the head non-cooling section of high-speed wire to solve the technical problems in the background.

[0006] To achieve the above purpose, the present application provides the following technical scheme: a production line for solving the low performance of the head non-cooling section of high-speed wire, comprising a heating furnace, roughing, pre-precision rolling, precision rolling, reducing sizing, pinch roll wire drawing machine, air cooling line and temperature control water tank, the heating furnace is connected with the roughing, the roughing is connected with the pre-precision rolling, the pre-precision rolling is connected with the precision rolling, the precision rolling is connected with the reducing sizing, the reducing sizing is connected with the pinch roll wire drawing machine, the pinch roll wire drawing machine is connected with the air cooling line, and the air cooling line is connected with the temperature control water tank.

[0007] Preferably, the air cooling line comprises a fan and an air box, the bottom of the fan is provided with a rotary fan, the upper side of the rotary fan is provided with an air box opening and a water pipe placement position, and the air box is provided with a plurality of groups of horizontally placed water pipes in plan view.

[0008] A process method for solving the low performance of the head non-cooling section of high-speed wire, comprising:

[0009] First step: optimize effective heating time, low temperature heating, refine the original austenite grain structure: cancel the preheating section heating, shorten the effective heating length and time in the furnace; Optimize and reduce the heating temperature of each section, adopt low temperature tapping, reduce the overall steel temperature from the source: set the furnace heating first section temperature 800-900℃, heating second section 1000-1100℃, soaking section 1000-1050℃, control the billet tapping temperature 900-950℃, austenite grain size in the range of 7-9 level, effective heating time 2-3h;

[0010] Second step: adopt segmented cooling in rolling process, control the final rolling temperature below 800℃: billet 900-950℃ low temperature opening, after 4 stands of rough rolling and 4 and 6 stands of medium rolling, cool down to 850-900℃ through 1# water tank, then after 4 stands of pre-precision rolling, cool down to 800-850℃ through 2-4# water tank, then after 6 stands of precision rolling, cool down to 730-780℃ through 5-6# water tank, finally control the final rolling temperature of the rolled piece at 750-800℃ after 4 stands of reducing diameter rolling;

[0011] Third step: adopt micro cooling process after final rolling: after the rolled piece is discharged from the final rolling, it passes through 7-8# water tank (the water tank is not opened at this time) and then is clamped by the pinch roll before being discharged, then the water system is opened to adopt micro water cooling process, and the temperature of the rolled piece is reduced by 50℃;

[0012] And set the water cooling pressure of each water tank as follows: 1#: 0.2-0.3Mpa, 2#: 0.25-0.35Mpa, 3#: 0.1-0.2Mpa, 4#: 0-0.1Mpa, 5#: 0.25-0.35Mpa, 6#: 0.15-0.25Mpa, 7#: 0.2-0.3Mpa, 8#: 0.1-0.2Mpa;

[0013] Fourth step: adopt air cooling and mist cooling mixed strengthening in the air cooling line to improve the overall cooling intensity of the product: reform the 1# air blower of the air cooling line to form air mist cooling, install 3 water pipes at the air box opening, arrange a certain number of nozzles in the length direction of the water pipes, open the air and water together to form air mist cooling process during production, enhance the cooling intensity, and further improve the overall performance of the product. By increasing the number of nozzles on both sides of the water pipe, the cooling intensity on both sides is improved, the disadvantage of slow cooling on both sides of the lap joint with high density of the coil is made up, and the performance uniformity is improved. The air blower opening degree is 95%, and the roller speed is increased from 0.6 to 1.2m / s,

[0014] Fifth step: control the length of the non-cooling section: the length of the non-cooling section at the head of the high-speed wire is affected by the final rolling speed, the distance between the final rolling and the pinch roll, the delay of signal transmission and the opening of the water cooling system, and in the ideal state, the water cooling is immediately opened after the pinch roll before the rolled piece is discharged to the coil, and the shortest length of the non-cooling section is the distance between the final rolling and the pinch roll.

[0015] Compared with the prior art, the present application has the beneficial effects that: a production line and process method for solving the low performance of the head non-cooling section of a high-speed wire rod mill, by canceling the preheating section heating, effectively shortening the heating time to 2-3h, reducing the steel tapping temperature to 900-950℃, refining the original austenite grain structure to 7-9 levels, reducing the gas consumption and oxidation loss, and improving the overall performance of the product; adopting the segmented strong cooling process during rolling and the weak cooling process after rolling, reducing the temperature of the finished product after the final rolling to 750-800℃, reducing the steel temperature of the head non-cooling section, and improving the performance of the head; precisely controlling the length of the non-cooling section to be within 10 turns, reforming the 1# air box to form a mixed strong cooling process of air cooling and mist cooling, and simultaneously strengthening the cooling intensity on both sides of the coil, improving the overall performance of the product, and reducing the performance difference of the same coil; through the above measures, the performance of the head non-cooling section of the high-speed wire rod mill is improved by 30-40MPa, the grain size is improved by 1 level, the national standard requirements are met, the head cutting is canceled, the yield and energy utilization rate are improved, and significant benefits are created for the enterprise. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The figure is a schematic diagram of the process structure of the present application;

[0017] Figure 2 The figure is a schematic diagram of the fan of the present application;

[0018] Figure 3 The figure is a schematic diagram of the air box mouth of the present application;

[0019] Figure 4 The figure is a comparison of the performance of the non-cooling section of the old process and the new process;

[0020] Figure 5 The figure is Figure 4 The metallographic photographs of serial number 1 and serial number 3.

[0021] In the figure: 1, heating furnace, 2, roughing and intermediate rolling, 3, pre-finishing rolling, 4, finishing rolling, 5, reducing sizing, 6, pinch roll wire spooling machine, 7, air cooling line, 701, rotary fan; 702, air box mouth; 7021, water pipe; 703, water pipe placement position; 8, temperature control water tank. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0023] Please refer to Figures 1-2The application provides a technical scheme: a production line for solving the low performance of a non-cooling section of a high-speed wire head, which comprises a heating furnace 1, rough and medium rolling 2, pre-precision rolling 3, precision rolling 4, reducing sizing 5, pinch roll wire rod delivery machine 6, air cooling line 7 and temperature control water tank 8, the heating furnace 1 is connected with the rough and medium rolling 2, the rough and medium rolling 2 is connected with the pre-precision rolling 3, the pre-precision rolling 3 is connected with the precision rolling 4, the precision rolling 4 is connected with the reducing sizing 5, the reducing sizing 5 is connected with the pinch roll wire rod delivery machine 6, the pinch roll wire rod delivery machine 6 is connected with the air cooling line 7, and the air cooling line 7 is connected with the temperature control water tank 8.

[0024] In the embodiment: the length of the non-cooling section is reduced, the finish rolling temperature of the rolled piece is reduced, the temperature drop of the rolled piece after finish rolling is reduced, and the measures such as air box mist cooling are taken, so that the problem of high temperature and low performance of the non-cooling section of the high-speed wire head is fundamentally solved, the high-speed wire head is not sheared, and the yield and enterprise benefits are improved.

[0025] Further, the air cooling line 7 comprises a fan and an air box, the bottom of the fan is provided with a rotary fan 701, the rotary fan 701 is provided with an air box opening 702 and a water pipe placing position 703 above, and the air box is provided with a plurality of groups of horizontally placed water pipes in plan view.

[0026] A process method for solving the low performance of a non-cooling section of a high-speed wire head comprises the following steps.

[0027] First step: optimizing effective heating time, low-temperature heating and refining original austenite grain structure: canceling preheating section heating, shortening the effective heating length and time in the furnace; optimizing and reducing the heating temperature of each section, taking low-temperature tapping, and reducing the overall steel temperature from the source: setting the heating first section temperature to 800-900 DEG C, the heating second section to 1000-1100 DEG C, the soaking section to 1000-1050 DEG C, and controlling the steel billet tapping temperature to 900-950 DEG C, so that the austenite grain size is in the range of 7-9 levels, and the effective heating time is 2-3 h;

[0028] In the embodiment: the old process is composed of a preheating section, a heating first section, a heating second section and a soaking section in the furnace of the heating furnace, and when the 165 steel billet is heated, a total of 180 steel billets can be placed in the furnace. Due to the small specification, single line and multiple passes of the high-speed wire, the hourly output is low, so that the steel billet stays in the furnace for a long time, which is in the range of 3-5 h, resulting in problems such as abnormal coarse original austenite grain and serious decarburization caused by long heating time, and serious oxidation loss and high coal gas consumption.

[0029] Second step: taking segmented cooling in the rolling process, and controlling the finish rolling temperature of the rolled piece to be below 800 DEG C: the steel billet is opened at a low temperature of 900-950 DEG C, and after being rolled by 4 rough rolling mills and 4 and 6 medium rolling mills, the rolled piece is cooled by a 1# water tank to a temperature of 850-900 DEG C, and then rolled by 4 pre-precision rolling mills, cooled by 2-4# water tanks to a temperature of 800-850 DEG C, rolled by 6 precision rolling mills, cooled by 5-6# water tanks to a temperature of 730-780 DEG C, and finally rolled by 4 reducing sizing mills, so that the finish rolling temperature of the rolled piece is controlled to be 750-800 DEG C.

[0030] Third step: after finish rolling, micro-cooling process is adopted: after the rolled piece is discharged from the finish rolling, it passes through the 7-8# water tank (at this time the water tank is not opened) and is clamped and discharged by the pinch roll, then the water passing system is opened to adopt the micro water passing process, and the temperature of the rolled piece is reduced by 50℃;

[0031] And the water passing pressure of each water tank is set as follows: 1#: 0.2-0.3Mpa, 2#: 0.25-0.35Mpa, 3#: 0.1-0.2Mpa, 4#: 0-0.1Mpa, 5#: 0.25-0.35Mpa, 6#: 0.15-0.25Mpa, 7#: 0.2-0.3Mpa, 8#: 0.1-0.2Mpa;

[0032] Fourth step: the air cooling line adopts the mixed strengthening of air cooling and mist cooling to improve the overall cooling intensity of the product: the air fan of the air cooling line 1# is reformed to form air mist cooling, three water pipes are installed at the air box mouth, a certain number of nozzles are arranged in the length direction of the water pipes, the air and water are opened together to form the air mist cooling process during production, the cooling intensity is enhanced, and the overall performance of the product is further improved. By increasing the number of nozzles on both sides of the water pipes, the cooling intensity on both sides is improved, the shortcomings of slow cooling on both sides due to large lap density of the coil are made up, and the performance uniformity is improved. The opening degree of the fan is 95%, and the roller speed is increased from 0.6 to 1.2m / s,

[0033] Fifth step: length control of non-cooling section: the length of the non-cooling section at the head of the high-speed wire is affected by the finish rolling speed, the distance between the finish rolling and the pinch roll, the delay of signal transmission and the opening of the water passing system, and in the ideal state, the water passing is immediately after the pinch roll before the rolled piece is discharged, and the shortest length of the non-cooling section is the distance between the finish rolling and the pinch roll.

[0034] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A process method for solving the problem of low performance in the non-cooled section at the head of high-speed wire rod, characterized in that: include: Step 1: Optimize effective heating time, low-temperature heating, and refine the original austenite grain structure: eliminate preheating section heating and shorten the effective heating length and time in the furnace; Optimize and reduce the heating temperature of each stage, and adopt low-temperature tapping to reduce the overall steel temperature from the source: set the temperature of the first stage of furnace heating to 800-900℃, the second stage heating to 1000-1100℃, the soaking stage to 1000-1050℃, control the billet tapping temperature to 900-950℃, keep the austenite grain size in the range of 7-9, and the effective heating time to 2-3 hours; Step 2: The rolling process adopts segmented cooling to control the final rolling temperature of the rolled piece below 800℃: the billet is rolled at a low temperature of 900-950℃, then rolled by 4 roughing stands and 6 intermediate stands, and then cooled back to 850-900℃ by water tank No.

1. After that, it is rolled by 4 pre-finishing stands, then cooled back to 800-850℃ by water tanks No. 2-4, then rolled by 6 finishing stands, then cooled back to 730-780℃ by water tanks No. 5-6, and finally rolled by 4 sizing stands to control the final rolling temperature of the rolled piece at 750-800℃. Step 3: Micro-cooling process after final rolling: After the rolled piece exits the final rolling, it passes through water tanks 7-8. At this time, water tanks 7-8 are not open. After being clamped by the pinch rollers and spinning, the water piercing system is turned on to adopt the micro-water piercing process, and the temperature of the rolled piece drops by 50℃. The water pressure for each tank is set as follows: #1: 0.2-0.3 MPa, #2: 0.25-0.35 MPa, #3: 0.1-0.2 MPa, #4: 0-0.1 MPa, #5: 0.25-0.35 MPa, #6: 0.15-0.25 MPa, #7: 0.2-0.3 MPa, #8: 0.1-0.2 MPa. Step 4: The air-cooling line employs a hybrid air-cooling and mist-cooling system to enhance overall product cooling intensity. The No. 1 fan of the air-cooling line is modified to create a mist-cooling system. Three water pipes are installed above the No. 1 fan's air box inlet, with a certain number of nozzles arranged along the length of the pipes. During production, both air and water are activated simultaneously to create a mist-cooling process, enhancing cooling intensity and further improving the overall product performance. By increasing the number of nozzles on both sides of the water pipes, the cooling intensity on both sides is increased, compensating for the relatively slow cooling due to the high overlap density on both sides of the coil, thus improving performance uniformity. The No. 1 fan is opened at 95%, and the roller conveyor speed is increased from 0.6 to 1.2 m / s. Step 5: Control of the length of the non-cooled section: The length of the non-cooled section at the head of the high wire rod is affected by the final rolling speed, the distance between the final rolling and the pinch rolls, and the delay in signal transmission and the opening of the water-cooling system. Ideally, the water should be quenched immediately after the pinch rolls before the wire is ejected, and the shortest length of the non-cooled section is the distance between the final rolling and the pinch rolls.

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