A method for designing the hole profile of irregularly shaped spherical flat steel.

Abstract

This invention discloses a roll pass design method for shaped bulb flat steel. The rolling process of this method involves 18 rolling mill passes. The first 16 mills use alternating horizontal and vertical passes, while the 17th and 18th mills are horizontal. The roughing and intermediate rolling area consists of 12 passes. The first 6 mills use box-type roll passes, the 7th to 12th mills use elliptical to circular roll passes, and the 13th to 17th mills use the shaped bulb flat steel roll pass system. The 18th mill passes are skipped. The roll pass system of the first 12 mills in this design method can be shared with existing round steel production lines. Only the roll pass system of the last 6 mills needs to be redesigned, without adding new mills. This method achieves shared production lines for round steel and shaped bulb flat steel while ensuring product quality. It not only enables rapid roll changes and flexible switching but also significantly shortens the traditional production cycle of shaped bulb flat steel, solving problems such as low manufacturing cost, high material utilization, and the risk of drawing cracks due to large cross-sectional area variations.

Description

Technical Field

[0001] This invention relates to a method for designing the hole pattern of a bulb flat steel bar, and more specifically to a method for designing the hole pattern of an irregularly shaped bulb flat steel bar. Background Technology

[0002] Traditional lock bodies are mainly made of materials such as cast iron, zinc alloy, and copper. Steel materials surpass these materials in various performance indicators, exhibiting resistance to breakage, high-temperature resistance, and the inability to be unlocked through destructive methods. However, the previous production process for shaped bulb flat steel—steelmaking-rolling (wire rod)-hot rolling-drawing-annealing-drawing—incurred significant drawbacks, including long production cycles, high manufacturing costs, low material utilization, large variations in cross-sectional area, and susceptibility to drawing cracks. These drawbacks severely restricted market expansion and prevented the replacement of cast iron, zinc alloy, and copper materials. Currently, no effective hole design method for shaped bulb flat steel has been proposed to address these technical problems. Summary of the Invention

[0003] Purpose of the invention: The present invention aims to provide a die design method for near-net-shape rolling of irregularly shaped spherical flat steel, which solves the problems of long production cycle, high manufacturing cost, low material utilization rate, and large cross-sectional area variation that easily leads to pull-out cracks in irregularly shaped spherical flat steel.

[0004] Technical Solution: The present invention describes a roll pass design method for shaped spherical flat steel. This method involves 18 rolling mill passes. The first 16 mills use alternating horizontal and vertical passes, while the 17th and 18th mills are horizontal. The roughing and intermediate rolling area comprises 12 passes. The first 6 mills use box-type roll passes, the 7th to 12th mills use elliptical-circular roll passes, and the 13th to 17th mills use the shaped spherical flat steel roll pass system. The 18th mill passes are skipped. The roll pass system for the first 12 mills in this design method can be shared with existing round steel production lines. Only the roll pass system for the last 6 mills needs to be redesigned, without adding new mills. This method achieves shared production lines for round steel and shaped spherical flat steel while ensuring product quality. It not only enables rapid roll changes and seamless switching but also significantly shortens the traditional production cycle for shaped spherical flat steel. It solves problems such as low manufacturing cost, high material utilization, and the risk of drawing cracks due to large cross-sectional area variations.

[0005] Preferably, the elongation coefficient of each pass in the irregular spherical flat steel die system is controlled between 1 and 1.5.

[0006] Preferably, the pass pattern for each pass of the irregular spherical flat steel pass system is designed independently, and the pass filling degree of each pass is verified by numerical simulation. The mill arrangement for this part is horizontal-vertical-horizontal-horizontal-horizontal, with the 14th and 16th stands being vertical mills designed for asymmetric rolling, and the exit size of the 12th stand being a circle with a diameter of Ф30mm to Ф45mm.

[0007] Preferably, the finished product size after rolling is from 20.8mm×Ф12.8mm×Ф5.8mm to 40.8mm×Ф20.8mm×Ф15.8mm.

[0008] Preferably, this method requires control over the billet heating temperature to ensure normal bite-in at each pass and prevent head cracking. The preheating section temperature of the heating furnace is ≤800℃, and the preheating time is ≥50min. The billet is heated slowly, and the heating and soaking temperatures in the heating furnace are controlled between 1100 and 1250℃. The high-temperature heating time above 1100℃ is ≥50min. The tapping temperature is controlled between 1150 and 1250℃. After high-pressure water descaling, the initial rolling temperature is controlled between 1050 and 1150℃ to avoid problems such as billet head slippage and cracking.

[0009] Preferably, the inlet and outlet of each pass of the irregular spherical flat steel rolling mill system are equipped with guide devices to ensure stability during the rolling process, wherein the inlet guide is a rolling guide and the outlet guide is a sliding guide.

[0010] Preferably, in order to reduce the bending phenomenon of irregularly shaped spherical flat steel during the cooling process, a fast-pushing conveying mode is adopted after the steel is rolled and placed on the cooling bed, that is, the cooling bed is continuously pushed forward without waiting for the steel to fill the cooling bed, and the total cooling time is ≤1000 seconds.

[0011] This invention aims to shorten the production process of irregularly shaped spherical flat steel by developing a die design method for near-net-shape rolling of irregularly shaped spherical flat steel. Only hot continuous rolling and one light drawing are required to obtain the lock core shell blank. This not only eliminates the spheroidizing annealing and drawing processes that downstream users previously added when processing irregularly shaped spherical flat steel from round steel, shortening the production cycle and reducing manufacturing costs, but also solves the problems of low material utilization and easy cracking during drawing of traditional steel lock body blanks. At the same time, it achieves the goals of carbon reduction, emission reduction, and efficiency improvement, and realizes the replacement of lock body materials such as cast iron, zinc alloy, and copper.

[0012] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) It greatly shortens the production cycle of traditional shaped spherical flat steel, solves the problems of low manufacturing cost, high material utilization rate, large cross-sectional area change that easily leads to drawing cracks, and can also achieve the purpose of carbon reduction, emission reduction and efficiency improvement, help the development of steel lock body and further increase market share; (2) The first 12 rolling mill pass system in this design method can be shared with the existing round steel. Only the last 6 rolling mill pass system needs to be redesigned. No new rolling mill is required. In the case of realizing the sharing of round steel-shaped spherical flat steel production line and ensuring the quality of physical products, it can not only realize quick roll change, free switching and improve production efficiency, but also save the additional hot rolling, annealing and drawing processes added by downstream users when using traditional round steel to process shaped spherical flat steel. From the perspective of the entire industrial chain, it has important application value and promotion significance. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the cross-section of an irregularly shaped spherical flat steel bar;

[0014] Figure 2 For each pass of the irregular spherical flat steel die system;

[0015] Figure 3 This is a production example diagram. Detailed Implementation

[0016] The technical solution of the present invention will be further explained below with reference to specific examples.

[0017] Example 1

[0018] The specific steps of the hole design method for the irregular shaped spherical flat steel are as follows:

[0019] (1) The preheating section temperature of the heating furnace is 680℃, and the preheating time is 50min; the heating section temperature is 1128℃, the soaking section temperature is 1170℃, and the high-temperature heating time above 1100℃ is 60min. The tapping temperature is 1170℃, and after high-pressure water descaling, the initial rolling temperature is controlled at 1105℃. The billet is successfully bitten in, and the head does not crack.

[0020] (2) A total of 18 rolling passes are used. The first 16 rolling stands are flat-vertical alternating, and the 17th-18th stands are flat rolling stands. The roughing and intermediate rolling area consists of 12 rolling passes. The pass system is not adjusted. The first 6 rolling stands are box-shaped passes, and the 7th-12th rolling stands are elliptical-round passes. The exit material shape of the 12 rolling stands is Ф40±0.6mm round.

[0021] (3) The 13th-17th stands of the rolling mill adopt the special-shaped spherical flat steel pass system (the pass types for each pass are as follows). Figure 2 As shown), the 18th mill stand passed empty. The arrangement of mill stands 13-17 is horizontal-vertical-horizontal-vertical-horizontal. The roll gap of mill stands 13-15 is 3mm, and the roll gap of mill stands 16-17 is 2mm.

[0022] (4) The dimensions of the rolled product are 35.8mm × Ф19.8mm × Ф12.8mm. The dimensional deviations of all hot-rolled products are controlled within ±0.5mm. The actual product image is shown below. Figure 3 As shown in the diagram, the cross-section of the irregularly shaped spherical flat steel is as follows: Figure 1 As shown.

[0023] (5) During the rolling process, guide devices are installed at the inlet and outlet of each pass of the irregular spherical flat steel roll pass system to ensure the stability of the rolling process. The inlet guide is a rolling guide and the outlet guide is a sliding guide.

[0024] (6) After the steel is rolled and placed on the cooling bed, a fast-push conveying mode is adopted, that is, the cooling bed is continuously pushed forward without waiting for the steel to fill the cooling bed. The overall curvature of the steel is controlled within a reasonable range, and it can be cut to length and packaged normally.

[0025] Example 2

[0026] (1) The preheating section temperature of the heating furnace is 700℃, and the preheating time is 55min; the heating section temperature is 1130℃, the soaking section temperature is 1180℃, and the high-temperature heating time above 1100℃ is 60min. The tapping temperature is 1180℃, and after high-pressure water descaling, the rolling temperature is controlled at 1110℃. The billet is successfully bitten in, and the head does not crack.

[0027] (2) A total of 18 rolling passes are used. The first 16 rolling stands are flat-vertical alternating, and the 17th-18th stands are flat rolling stands. The roughing and intermediate rolling area consists of 12 rolling passes. The pass system is not adjusted. The first 6 rolling stands are box-shaped passes, and the 7th-12th rolling stands are elliptical-round passes. The exit material shape of the 12 rolling stands is Ф35±0.6mm round.

[0028] (3) The 13th-17th stands of the rolling mill adopt the special-shaped spherical flat steel pass system (the pass types for each pass are as follows). Figure 2 As shown), the 18th mill stand passed empty. The arrangement of mill stands 13-17 is horizontal-vertical-horizontal-vertical-horizontal. The roll gap of mill stands 13-15 is 3mm, and the roll gap of mill stands 16-17 is 2mm.

[0029] (4) The dimensions of the rolled product are 30.5mm×Ф15.2mm×Ф8.8mm, and the deviation of each dimension of the hot-rolled product is controlled within ±0.5mm.

[0030] (5) During the rolling process, guide devices are installed at the inlet and outlet of each pass of the irregular spherical flat steel roll pass system to ensure the stability of the rolling process. The inlet guide is a rolling guide and the outlet guide is a sliding guide.

[0031] (6) After the steel is rolled and placed on the cooling bed, a fast-push conveying mode is adopted, that is, the cooling bed is continuously pushed forward without waiting for the steel to fill the cooling bed. The overall curvature of the steel is controlled within a reasonable range, and it can be cut to length and packaged normally.

Claims

1. A method for designing the die profile of an irregularly shaped spherical flat steel bar, characterized in that, The rolling process of this method involves 18 rolling mill passes. The first 16 mills use alternating horizontal and vertical passes, while the 17th and 18th mills are horizontal mills. The roughing and intermediate rolling area consists of 12 mill passes. The first 6 mills use box-shaped passes, the 7th to 12th mills use elliptical to round passes, the 13th to 17th mills use a special-shaped spherical flat steel pass system, and the 18th mill passes without rolling. The elongation coefficient of each pass in the irregular spherical flat steel die system is controlled between 1 and 1.

5. The 14th and 16th stands of the irregular spherical flat steel rolling mill system are vertical rolling mills, and the exit size of the 12th stand rolling mill is a circle with a diameter of Ф30mm to Ф45mm. The dimensions of the rolled finished product range from 20.8mm×Ф12.8mm×Ф5.8mm to 40.8mm×Ф20.8mm×Ф15.8mm; This method requires controlling the temperature of the preheating section of the heating furnace to ≤800℃ and the heating time of the preheating section to ≥50min; the tapping temperature to be controlled between 1150 and 1250℃; and the initial rolling temperature to be controlled between 1050 and 1150℃ after descaling with high-pressure water.

2. The die design method for irregularly shaped spherical flat steel according to claim 1, characterized in that, The temperature of the heating section and the soaking section in the heating furnace is controlled between 1100 and 1250°C, and the high-temperature heating time above 1100°C is ≥50 min.

3. The hole design method for irregularly shaped spherical flat steel according to claim 1, characterized in that, The inlet and outlet of each pass of the irregular spherical flat steel pass system is equipped with a guide device.

4. The hole design method for irregularly shaped spherical flat steel according to claim 3, characterized in that, The inbound guide is a rolling guide, and the outbound guide is a sliding guide.

5. The hole design method for irregularly shaped spherical flat steel according to claim 1, characterized in that, After the steel is rolled and placed on the cooling bed, it adopts a fast-pushing conveying mode, with a total cooling time of ≤1000 seconds.

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