JPS6338247B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a conveying roller table and a quenching machine that can be freely replaced with the unloading roller table of a rolling mill, selectively quenching and conveying a rolled steel plate, and increasing the quenching speed. This invention relates to a quenching device for rolled steel plates that adjusts the thickness to an appropriate value.

Conventionally, as a method of directly quenching a steel plate discharged from a rolling mill without reheating it in a heating furnace, a quenching machine 3 is interposed on a roller table 2 on the downstream side of a rolling mill 1, as shown in FIG. and rolling mill 1
A first method of applying laminar flow water or sprayed water to the steel plate in a quenching machine while maintaining an exit table speed of e.g. 120 or 150 m/min;
In addition, as shown in FIG. 2, a transfer car 4 is installed on the roller table 2 to temporarily stop the steel plate 5 conveyed by the roller table 2, and then to place the steel plate 5 in parallel along the roller table 2. There is a second method in which the steel plate is moved to the hardening line, then re-accelerated and transported to the hardening machine 3, and then hardened in the same manner as in the case of FIG. 1st
In the figure and FIG. 2, 6 is a cooling bed.

However, in the first method, the conveyance speed of the steel plate carried into the hardening machine 3, that is, the conveyance speed of the roller table, is independent of the thickness of the steel plate.
Since the exit table speed of the rolling mill 1 is high and constant, it is necessary to provide a hardening machine 3 having a hardening machine length that can sufficiently harden even thick steel plates that require a long cooling time. This quenching machine has a longer quenching machine length than necessary for thin steel plates, increases pump power, etc., and also reduces cooling efficiency especially when the plate is thick, resulting in poor hardenability even with the same amount of water. There is a problem with this.
In addition, the steel plate is supported from below by a roller conveyor, and cooling water is applied from above by laminar flow or spray at approximately 90 degrees to the steel plate, so the way the cooling water is applied to the upper and lower surfaces of the steel plate is controlled. The difference is significant, resulting in uneven quenching and large deformation of the steel plate, and once deformation begins, the deformation increases and can even lead to equipment damage. The above-mentioned method of applying cooling water also causes the cooling water that hits the steel plate to flow upstream of the steel plate, making it impossible to maintain its consistency, so the cooling start point is not constant, which causes uneven quenching and deformation. In some cases, hardening may not be possible. Furthermore, since the quenching machine is configured to operate in conjunction with the rolling mill line, maintenance and inspection of only the quenching machine requires the entire rolling mill line to be stopped, resulting in a decrease in productivity. .

In addition, in the second method, in addition to the above-mentioned problems caused by laminar cooling, the steel plate temperature is significantly lowered because the steel plate is stopped, moved, and reheated, resulting in uneven hardening. In addition, the above-mentioned large temperature drop will cause the temperature of a thin steel plate of 20 mm or less to fall below the austenitizing temperature, making it impossible to harden the steel plate. In other words, there is a limit to the plate thickness that can be hardened. Also, while the transfer car 4 is moving to the quenching line,
Since the roller table 2 is suspended, it cannot transport the steel plate from the rolling mill 1, which significantly reduces productivity.

The present invention was devised to solve the drawbacks of the above-mentioned conventional methods, and its purpose is to provide a conveying roller table and a quenching machine in the middle of a roller table connected to a rolling mill so that they can be exchanged with each other. To provide a quenching device for rolled steel plates that can shorten the length of the quenching machine while processing the steel plates according to the type of rolled steel plate by adjusting the speed at which the rolled steel plates are carried into the machine in accordance with the thickness of the steel plate. be.

Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 3, FIG. 4, FIG. 5, and FIG. 6 show a hardening apparatus 10 for rolled steel sheets in which the present invention is implemented. This hardening device 10 is a rolling machine that heats the steel material in a heating furnace (not shown) to a temperature higher than the austenitizing temperature and rolls the steel material carried in by the roller table 11 into a steel plate of a predetermined thickness while maintaining the steel material at the austenitizing temperature or higher. 12, an upstream roller table 15 and a downstream roller table 16, which are provided so as to be able to freely control the speed, in order to convey the rolled steel plate 13 from the rolling mill 12 to the cooling bed 14, and the rolling mill 12.
Both the roller tables 1 are used when the rolled steel plate 13 from the
a conveying roller table 17 inserted between the roller tables 15 and 16; a hardening machine 18 inserted between the roller tables 15 and 16 when hardening the rolled steel plate 13 from the rolling mill 12; A conveying roller table 17 is inserted between both roller tables 15 and 16, and when conveying the rolled steel plate 13 without quenching, the conveying speed of the upstream roller table and the conveying roller table is controlled at high speed, and the quenching machine 18 is inserted, and when hardening the rolled steel plate 13, the roller table 1 on the upstream side responds to the plate thickness signal from the rolling mill 12.
Control the conveyance speeds of the upstream roller table 15 and the quenching machine 18 so that the conveyance speeds of the upstream roller table 15 and the quenching machine 18 are within the range of 100≦quenching speed (m/min)×thickness (mm) of the rolled steel plate≦1000. It mainly consists of a speed control device 19.

As shown in FIG. 3, this conveyance roller table 17 has rails 20 laid at right angles to the upstream and downstream roller tables 15 and 16.
The roller table portion is configured to be able to travel on this rail 20.

Further, as shown in FIG. 3, the hardening machine 18 includes roller tables 15 on the upstream side and downstream side,
A rail 20 is laid at right angles to the rail 16, on which a hardening machine trolley 21 (see FIGS. 5 and 6) can run, and a fixed lower roller 22 is provided at the bottom of the trolley 21. An upper roller 24 that can be moved up and down by an elevator 23 is provided on the upper part of the truck 21, and cooling water spray nozzles 25 and 26 are provided between these rollers, and the nozzle angle θ of the inlet cooling water spray nozzle 25 is provided.
(See Figure 5) is especially 5 degrees ≦ θ ≦ to prevent backflow.
The angle is set at 30 degrees so that the nozzle 25 faces the rolled steel plate 13. In FIG. 6, 27 is a hardening machine pipe, 28 is a universal joint, and 29 is a fixed pipe.

In this way, the conveying roller table 17 and the hardening machine 18 are connected to both the roller tables 15 and 1.
The roller tables 15 and 16 are provided parallel to the conveying direction on a rail 20 laid perpendicularly to the conveying direction of the rolling mill 12 between the two roller tables 15 and 16, and are alternately moved on the rail 20 to change places between the two roller tables 15 and 16. It is becoming more and more selectively located.

As shown in FIG. 3, the speed control device 19 is provided with a steel plate speed measuring device 30 near the rear end of the roller table 15 on the upstream side, which measures the conveying speed of the rolled steel plate. In other words, the quenching speed (m/min) in the quenching machine 18 and the rolling mill 1
An upstream roller table drive device 31 and a quenching machine roller drive device 3 receive the plate thickness t (mm) of the rolled steel plate sent from No. 2 via a signal line (not shown).
It is composed of 2. Both drive devices 3
As mentioned above, 1,32 is 100≦V (m/min)×
The upstream roller table 15 and the rollers 22 and 24 are configured to be driven so that t (mm)≦1000. 100≦V (m/min)×t (mm)≦
As shown in Figure 7, the condition of 1000 improves the hardenability.
These are the conditions required to maintain it at 80% or higher. This hardenability will be explained when explaining the operation of the apparatus of the present invention. V (m/min)×t
(mm)≦100, the steel plate temperature falls below the austenitizing temperature and hardening becomes difficult, and V (m/min) ×
When t (mm)>1000, the table speed becomes too fast and the hardenability decreases.

Next, the operation of the device of the present invention will be explained.

When hardening of the rolled steel plate 13 rolled by the rolling mill 12 is not necessary, a conveying roller table 17 is inserted between the upstream roller table 15 and the downstream roller table 16, and the rolling steel plate 13 is rolled by the rolling mill 12. The rolled steel plate transported at a high speed of 120 or 150 m/min is transported to the cooling bed 14 via the upstream roller table 15, the transport roller table 17, and the downstream roller table 16.

Next, the case where the rolled steel plate 13 is subjected to quenching treatment will be described. When quenching the rolled steel plate 13, there are two cases: quenching by reheating it, and quenching while maintaining the rolled steel plate 13 at a temperature equal to or higher than the austenitizing temperature as in the present invention. In these hardening treatments, hardenability refers to the property that controls the distribution and depth of the martensitic structure.
In the present invention, this hardenability was considered as follows.

Generally, when the entire structure of a rolled steel plate becomes martensitic for a thin plate of 30 mm or less, it is difficult to harden a thick plate of more than 30 mm. When the depth structure becomes martensitic, the quenching process is considered complete and the product is commercialized. Therefore, for convenience, the hardenability is defined as 100% when all of the rolled steel sheets that have been hardened can be manufactured into products under the above-mentioned conditions. In the case of the above-mentioned reheating and quenching, this hardenability of 100% can be obtained, but when quenching is performed without reheating and maintaining the rolled steel plate 13 at a temperature higher than the austenitizing temperature as in the present invention, the rolling steel plate 13 is The temperature of the steel plate 13 may drop below the austenitizing temperature during conveyance in the rolling mill 12 or the upstream roller table 15, making it impossible to commercialize all the steel plates and reducing the hardenability to 100.
It is not possible to get %. In the present invention, in order to commercialize 80% of the rolled steel plates 13 to be hardened under the above-mentioned conditions, a hardenability of 80% is adopted, and the apparatus of the present invention is operated as follows.

When the rolled steel plate 13 requires hardening, a hardening machine 18 is inserted between the roller table 15 and the roller table 16. Along with this, the plate thickness t (mm) signal from the rolling mill 12 and the conveyance speed V (m/min) signal from the steel plate speed measuring device 30 are connected to the upstream roller table drive device 31 and the quenching machine roller drive device. 32. In both of these drive devices 31 and 32, 100≦V obtained from FIG. 7 as the condition for the hardenability of 80% or more.
(m/min) x t (mm)≦1000 is checked to see if the condition is met, 120m/min or 150m/min.
The rolled steel plate 13 conveyed at a high conveyance speed of min is usually conveyed under control, and the rolled steel plate 13 is conveyed through a hardening machine 18 at a hardening speed according to the plate thickness.

Since the quenching speed can be changed according to the plate thickness in this way, the length of the quenching equipment can be significantly shortened compared to conventional methods. For example, under the condition of V (m/min) x t (mm) = 1000, the quenching speed V of the rolled steel plate 13 with a plate thickness t of 50 mm is 20 m/min, and the equipment length required for this quenching is 35 m. In contrast, the length of equipment required to harden a rolled steel plate 13 with a thickness of 50 mm at a conveyance speed of 120 m/min using a conventional roller table is
It is 240m. Comparing these results shows that the equipment length has been significantly shortened. Therefore, the power source equipment is also reduced. In addition, in the equipment length as described above, the thicker the plate thickness t, the greater the deceleration rate of the quenching speed V, so the cooling efficiency remains constant,
Hardenability improves. In this way, the conveyance speed of the steel plate 13 is reduced during quenching, but the steel plate 1
3 is continuously taken over by the quenching process without being stopped, so the temperature drop of the steel plate 13 is small, and the 10
Thin plates of about mm to 6 mm can also be hardened. Since the rolled steel plate 13 is hardened at a reduced speed, the life of the hardening machine 18 is extended.

Longer life of the hardening machine 18 is also facilitated by inserting the hardening machine 18 only when hardening the steel plate 13 and reducing the operating time of each part of the hardening machine 18, especially the roller part.

In addition, the remaining 20% of rolled steel sheets 13 cannot be commercialized.
The method involves reheating and quenching again.

Further, since the quenching machine 18 can be maintained and inspected off-line and does not require stopping the rolling line, the productivity of the rolling mill 12 will not be reduced due to maintenance and inspection of the quenching machine 18.

Also, set the spray angle θ of the inlet nozzle to 5 degrees ≦ θ ≦
Since the temperature is set at 30 degrees, there is no backflow, so the cooling start point can be set in a straight line, and uneven hardening and cooling do not occur.Therefore, deformation can be kept to a minimum and the hardening quality can be improved.

Furthermore, by providing the upper roller, the flow of water on the upper and lower surfaces of the steel plate is the same, so the cooling rate is constant, which not only prevents deformation, but also allows the upper spray nozzle to be lowered to near the steel plate surface. This improves the cooling rate and reduces deformation of the steel plate.

As described above, since the amount of deformation of the steel plate can be reduced from various aspects, damage to equipment such as spray nozzles due to deformation of the steel plate is prevented.

As is clear from the above description, according to the present invention, the following effects can be obtained.

The conveyance and quenching of the rolled steel plate can be carried out selectively while the rolling mill is continuously operated.

The length of the quenching equipment can be significantly shortened.

The capacity of the power source equipment can be reduced or reduced.

Cooling efficiency and therefore hardenability are improved.

It becomes possible to harden thin steel sheets.

The life of the hardening machine is extended.

Quenching inspection and maintenance can be done offline.

Does not reduce productivity of rolling mill.

etc.

[Brief explanation of the drawing]

1 and 2 are diagrams showing an example of a conventional device, FIG. 3 is a diagram showing the device of the present invention, FIG. 4 is a front view of a roller conveyor on the upstream side of the device of the present invention, and FIGS. The figures are a side view and a front view of a mobile hardening machine of the present invention, respectively, and FIG. 7 is a hardenability-vt curve diagram. In the figure, 10 is the device of the present invention, 12 is a rolling mill, and 15
1 is a roller table on the upstream side, 16 is a roller table on the downstream side, 17 is a conveying roller table, 18 is a hardening machine, and 19 is a speed control device.

Claims (1)

[Claims] 1. A rolling mill that rolls the heated steel material to a predetermined thickness while maintaining the temperature above the austenitizing temperature;
A roller table on the upstream side and a roller table on the downstream side are provided to be able to freely control the speed to convey the rolled steel plate following the rolling mill, and roller tables are provided in parallel to the conveyance direction between these two roller tables and are arranged alternately. a conveying roller table and a quenching machine that are selectively positioned between the two roller tables; and a conveying roller table and a hardening machine that are selectively positioned between the two roller tables; The conveying speed of the upstream roller table and the quenching machine is controlled to be the same as the conveying speed of the rolling mill, and when the quenching machine is located between the two roller tables, the conveying speed of the upstream roller table and the quenching machine is controlled to be 100≦quenching. A quenching device for rolled steel sheets, comprising a speed control device that controls speed (m/min) x plate thickness (mm)≦1000.