JPH0824911A - Seamless pipe rolling and rolling equipment - Google Patents

Abstract

PURPOSE:To improve condition of the inner surface of a tube in an expansion rolling device, by providing the tip end of a pusher with a port for jetting water for the purpose of descaling the inner surface of a hollow tube stock and/or a port for jetting lubricant for lubricating the inner surface of the hollow tube stock. CONSTITUTION:An jetting header 33 whose diameter is smaller than the inside diameter of a hollow tube stock 1 is provided nearly fixedly at the tip end of a pusher 30; and the jetting header 33 is provided with a water jetting port 34 and/or a lubricant jetting port 35 for lubricating the inner surface of the hollow tube stock; and a feeding piping is extended by which water and lubricant are supplied to each jetting port 34, 35. Consequently, in this case, water and lubricant are stably supplied to the part immediately before rolling on the inner surface of the hollow tube stock 1, in an expansion rolling mill 20 (without extending a rolling line) and with a simple piping structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seamless pipe expanding and rolling apparatus such as a seamless steel pipe.

[0002]

2. Description of the Related Art The Mannesmann method is the mainstream in the manufacturing process of seamless pipes, and it is roughly classified into a plug mill method and a mandrel mill method depending on the rolling method. It consists of a piercing step, a drawing and rolling step of thinning and drawing the pierced hollow shell, and a finish rolling step of squeezing the drawn and rolled hollow shell to a predetermined outer diameter or a constant diameter.

In the conventional drawing and rolling process, the expansion ratio is about several to 17 or 18% at most in the elongator for thinning and expanding the hollow shell and in the reeler for polishing by thinning and expanding. Therefore, in order to obtain products with a wide range of outer diameters, billets with various outer diameters are required, which is one factor that hinders productivity. for that reason,
In recent years, a high pipe rolling schedule has been proposed in which the pipe is expanded more than before in the drawing process for the purpose of reducing the material billet size and simplifying the equipment. Here, high expansion means that the expansion ratio Er is 0.2 or more.

However, in the high tube rolling process, in order to secure the rolling temperature in the tube rolling mill, if a reheating furnace is placed on the inlet side of the rolling machine and the material to be rolled (hollow shell tube) is heated, the material to be rolled is rolled. Oxide scale is generated and grows on the inner and outer surfaces of. Although the pipe outer surface scale easily separates and drops during the rotational movement of the pipe on the transport table, if the pipe inner surface scale is rolled as it is, it will be pressed by the plug and will cause a flaw on the inner surface of the pipe. Even when the reheating process is not provided on the inlet side of the pipe rolling mill, the pipe inner surface scale of the material to be rolled grows during the transportation from the preceding rolling mill (for example, the mandrel mill) to the pipe rolling mill. I have a problem.

Conventionally, in a seamless tube rolling process, in order to prevent the occurrence of flaws on the inner surface of the pipe, as described in JP-A-61-74714, a nozzle for injecting cooling water and / or a lubricant at the tip of the plug is disclosed. Is provided (FIG. 6), and cooling water and / or a lubricant is sprayed from this nozzle to the contact surface between the inner surface of the material to be rolled and the outer surface of the plug.

[0006]

However, the plug provided with the above-mentioned injection nozzle is detachably provided at the tip of the plug bar, and the cooling water and / or lubricant supply pipe is plugged from the plug bar. Will be extended towards. In addition, the attachment and detachment of the plug to the plug bar is
(a) Replacing the plug when changing the size of the rolled material, (b) Replacing each rolled material to cool and recycle the rolled plug, and (c) To clean the plug. It is indispensable for exchanging plugs.

Therefore, in the prior art, the cooling water and / or lubricant supply pipe is routed through the attachment / detachment portion between the plug bar and the plug, and as a result, (1) the cooling water and / or lubricant is (2) Cooling water and / or lubricant is extremely difficult to maintain stable supply pipes with no blockage for a long period of time in order to make it possible to supply water without leaking at the attachment / detachment part. When the above-mentioned attachment / detachment part clogs or leaks, the required amount of cooling water and / or lubricant cannot be supplied, and it becomes impossible to prevent the occurrence of flaws on the inner surface of the pipe. (3) Cooling water that has leaked to the inner surface of the pipe cannot be prevented. In order to cool the material to be rolled and increase its deformation resistance, the rolling load is excessively increased, and the required amount of pipe expansion cannot be obtained.

As another technique for preventing the occurrence of flaws on the inner surface of the pipe, it is conceivable to provide a descaler on the inner surface of the pipe immediately before the pipe rolling mill. However, in this case, an independent descaler is installed in the rolling line, which lengthens the line length, and the reheating temperature must be increased to compensate for the temperature drop of the material to be rolled on the line. As a result, the degree of generation of the pipe inner surface scale becomes excessive, so that the inner surface of the pipe after rolling cannot be made very good.

The present invention makes it possible to stably supply water and / or a lubricant to the inner surface of the pipe immediately before rolling with a simple structure,
The purpose is to improve the inner surface properties of the pipe.

[0010]

DISCLOSURE OF THE INVENTION The present invention is directed to a pipe rolling mill in which a pair of rolling rolls are arranged at an inclination with respect to a pass line at a constant advance angle, and a plug is arranged between the pair of rolling rolls. In the seamless pipe expanding and rolling apparatus having a pusher for engaging the hollow shell in the tube expanding and rolling machine, the tip of the pusher has a water injection port for descaling the inner surface of the hollow shell. And / or a lubricant injection port for lubricating the inner surface of the hollow shell is provided.

[0011]

[Operation] In the structure in which the water injection port and the lubricant injection port are provided at the tip of the pusher, an injection header having a diameter smaller than the pipe inner diameter is almost fixedly provided at the tip of the pusher, and these water injection ports are provided at the injection header. The lubricant injection port is provided, and the water injection port provided in the injection header from the pusher and the supply pipe for supplying water and the lubricant toward the lubricant injection port are extended. Therefore, in this case, in the pipe rolling mill (without making the rolling line intentionally long) and with a simple piping configuration, water and lubricant can be stably supplied to the inner surface of the pipe immediately before rolling without clogging or leakage. it can.

As described above, the water and the lubricant can be stably supplied in the required amounts without being clogged or leaking in the supply pipe system, so that the inner surface of the pipe can be prevented from being flawed. Further, the required amount of pipe expansion can be obtained without the water leaking to the inner surface of the pipe cooling the rolled material and increasing its deformation resistance.

According to the above, the water and the lubricant are supplied to the material to be rolled in the tube rolling mill, and for the purpose of compensating for the temperature drop of the material to be rolled when the rolling line length becomes long by providing a special descaler in front of the rolling mill. No need to reheat at high temperature. For this reason, it is possible to make the inner surface of the pipe after rolling good without excessive generation of the inner scale of the pipe due to reheating at high temperature.

[0014]

EXAMPLE FIG. 1 is a schematic view showing an embodiment of the tube rolling mill, FIG. 2 is a schematic diagram showing a rolling start state by the tube rolling mill, and FIG. 3 is a schematic diagram showing a rolling state by the tube rolling mill. 4 is an enlarged view of a main part of FIG. 3, FIG. 5 is a schematic view showing the effect of the present invention, FIG. 6 is a schematic view showing a conventional example, and FIG. 7 is a view when pipe rolling is performed by changing the metal thinning rate and the tube expansion rate. Bad bite,
FIG. 7 is a diagram showing the occurrence of hollow breakage due to defective trailing and flaring.

The pipe rolling mill 10 has a pipe rolling mill 20 and a pusher 30. The tube rolling mill 20 is shown in FIGS.
As shown in detail in FIG.
21 is inclinedly arranged at a constant advance angle β, and is also arranged at a crossing angle γ with respect to the pass line so as to have an entrance side surface angle α ₁ and an exit side surface angle α ₂ . And the pipe rolling mill 20
Includes a plug 22 inserted into the hollow shell 1 between the rolling rolls 21 and 21, and a guide shoe 23 that guides the outer surface of the hollow shell 1 between the rolling rolls 21 and 21. Two
2A is a plug bar. The guide shoe 23 may be a fixed type, a disc type, a roller type, or a drive roller type.

The pusher 30 allows the hollow shell 1 to be caught in the tube rolling mill 20. The pusher 30 is fixedly provided with a pusher header 32 at the tip of a piston rod of a pusher cylinder 31, and the pusher header 32 that is advanced by the extension operation of the cylinder 31 contacts the rear end surface of the hollow shell 1 to expand the shell 1. Rolling roll 2 of rolling mill 20
Push toward 1, 21.

In the pipe rolling apparatus 10, however, in the pusher 30, the injection header 33 having a diameter smaller than the inner diameter of the hollow shell 1 is fixed to the tip of the pusher header 32, and the outer peripheral surface of the injection header 33 on the tip side. The water injection ports 34 are opened at a plurality of circumferential positions, and the lubricant injection port 35 is opened at the tip end surface of the injection header 33. Then, a water supply passage 34A and a lubricant supply passage 35A are extended from the pusher header 32 toward the injection header 33, and water and a lubricant can be supplied to the water injection opening 34 and the lubricant injection opening 35 at a predetermined pressure. I am trying. The water jetted from the water jet port 34 is supplied to the inner surface of the hollow shell 1 to descale the inner surface of the shell 1. The lubricant injected from the lubricant injection port 35 lubricates the contact area between the inner surface of the hollow shell 1 and the plug 22.

The pusher 30 operates as described in (1) to (3) below. (1) The pusher header 32 and the injection header 33 are retracted until the hollow shell 1 is loaded on the inlet side of the pipe rolling mill 20 (FIG. 1).

(2) When the hollow shell 1 is placed on the inlet side of the tube rolling mill 20, the pusher header 32 advances toward the hollow shell 1. Even after coming into contact with the rear end surface, the tube 1 is further advanced to be caught in the tube expanding and rolling mill 20. At this time, the injection header 33 is inserted into the inner diameter portion of the hollow shell 1, sprays the lubricant from the lubricant spray port 35 toward the contact area between the inner surface of the shell 1 and the plug 22, and High-pressure water is jetted from the jet port 34 toward the inner surface of the raw pipe 1 (FIG. 2).

(3) Even during the rolling of the hollow shell 1 by the tube rolling mill 20, as in the case of (2), the contact area between the inner surface of the hollow shell 1 and the plug 22 is extended from the lubricant injection port 35. The lubricant is jetted toward the inner surface of the raw tube 1 from the water jet port 34 (FIG. 3).

The details of the pipe rolling mill 20 used in this embodiment will be additionally described. In the tube rolling mill 20, the cone-shaped rolls are inclinedly arranged at a constant advancing angle β and are arranged at a crossing angle γ with respect to the pass line, so that the roll diameter is temporarily increased toward the rolling-out side and the peripheral speed is increased. As a result, the roll exerts a slight brake on the rolled material. Therefore, in the inclined rolling by the pipe rolling mill 20,
Due to the brake exerted on the rolled material by the roll, the twist of the rolled material and the generation of additional shear strain in the cross section are suppressed,
A hollow shell can be highly expanded without causing a bite of the shell, a slip-out, and a hollow break due to flaring.

However, the inventors of the present invention have confirmed the occurrence of defective biting of the material to be rolled, defective slippage of the rolled material, and tearing of the hollow due to flaring when highly expanding and rolling the hollow shell by the cone-shaped rolls that are arranged crosswise. As a result of a detailed study, a pair of cone type rolling rolls have a constant lead angle β with respect to the pass line.
In addition to sloping at a crossing angle of γ with respect to the pass line so as to have an entrance side angle α ₁ and an exit side angle α ₂ with respect to the pass line, in order to expand the hollow shell highly, , Γ, β + γ are set within the following range, and 5 ° ≦ β ≦ 2
5 °, 10 ° ≦ γ ≦ 40 °, 20 ° ≦ β + γ ≦ 50 ° and α ₁ ,
Set α ₂ in the range below and set 0.5 ° ≤ α ₁ ≤
5 °, 3 ° ≤ α ₂ ≤ 10 °, α ₁ ≤ α ₂ , and the metal loss rate R
_{Between t} and expansion ratio E _r , 1 ≤ E _r / R _t ≤ 3, but R
_t = (t _i -t _o ) / t _i , E _r = (D _o -D _i ) / D _i ,
t _i : wall thickness of inlet hollow shell, D _i : outer diameter of inlet hollow shell, t
By satisfying the relations of _o : outlet pipe wall thickness, D _o : outlet pipe outer diameter, it is possible to remarkably prevent the occurrence of bite failure, defective tail slippage, and hollow breakage due to flaring, yield, and productivity. It was found that high pipe rolling can be performed without hindering the above.

[0023] That is, the cone-type roll, as shown in FIGS. 1 to 4 GORE - di section diameter D _R is 700 mm, the roll barrel length L
_R is 600 mm, roll length L ₁ from the entrance end to the gorge part
Is 250 mm, the entrance side angle α ₁ is 3 °, the exit side angle α ₂ is 5 °,
It is an inclined rolling mill with a crossing angle γ of 20 ° and a lead angle β of 15 °. It uses a hollow shell with a diameter _DH of 80 to 120 mm and a wall thickness t _H of 15 to 40 mm as the material to be rolled, and the roll gap E and the plug are advanced. The amount L was variously changed and the wall-thickness reduction ratio R _t and the pipe expansion ratio E _r were changed for pipe expansion rolling, and the occurrence of hollow biting due to defective biting and flaring was investigated. FIG. 7 shows the results organized by taking R _{t on} the horizontal axis and E _r on the vertical axis.

As is clear from the figure, a pair of cone-type rolling rolls are arranged at an inclination with a constant advance angle β, and γ
In the inclined rolling method of tubes crossing arrangement, thinning rate R _t
And tube expansion ratio E _r in the range of 1 ≤ E _r / R _t ≤ 3, it is possible to avoid defective biting, defective slippage, and hollow breakage due to flaring, and the degree of freedom in rolling setting is improved. It is possible to raise it.

In the present invention, 5 ° ≦ β ≦ 25 °, 10 ° ≦
The reason for setting γ ≦ 40 ° and 20 ° ≦ β + γ ≦ 50 ° is as follows. Within a certain range, the larger the advancing angle β, the crossing angle γ, and the sum β + γ, the more the twist of the material to be rolled and the additional shear strain in the cross section can be reduced, which prevents the hollow tear due to flaring. Effective against
However, β <5 °, or γ <10 °, or β + γ <20
If the angle is °, the effect is not sufficient and hollow breakage due to flaring tends to occur. Therefore, the lower limit of β is 5 °, γ
The lower limit of is 10 °, and the lower limit of β + γ is 20 °. On the other hand, β>
At 25 °, γ> 40 °, or β + γ> 50 °, the twist of the material to be rolled increases in the opposite direction, and additional shear strain in the cross section also occurs in the opposite direction, rather causing hollow tear due to flaring. It tends to occur. Therefore, β is 25 ° and γ is
40 ° and β + γ shall not exceed 50 °.

The reason why 0.5 ° ≦ α ₁ ≦ 5 ° is set is as follows. The entrance side angle α ₁ has an important influence on the biting property of the material to be rolled. If α ₁ exceeds 5 °, the material to be rolled is drastically reduced during biting, and the drag force from the rolling roll required for deformation exceeds the thrust in the forward direction transmitted from the rolling roll. . Therefore, α ₁ is 5 °
Shall not be exceeded. On the other hand, if α ₁ becomes too small, it is necessary to considerably lengthen the roll barrel on the inlet side in order to obtain the outer diameter reduction of the material to be rolled necessary for the thrust in the forward direction. Becomes higher and not practical. Therefore, the lower limit of α ₁ is 0.5 °.

The reason why 3 ° ≦ α ₂ ≦ 10 ° is set is as follows. The larger the flank angle α ₂ is, the shorter the roll barrel on the exit side, which is necessary for the amount of pipe expansion, and the equipment can be downsized, but if it is too large, hollow breakage due to flaring will occur. Is likely to occur.
Therefore, α ₂ shall not exceed 10 °. On the other hand, α ₂
If is too small, it is necessary to lengthen the roll barrel on the outlet side considerably in order to obtain a predetermined amount of pipe expansion, resulting in high facility construction cost and impracticality. Therefore, the lower limit of α ₂ is 3 °.

The reason why α ₁ ≦ α ₂ is set is as follows.
When the exit side angle α ₂ becomes smaller than the entrance side angle α ₁ , in order to obtain a predetermined pipe expansion amount, the roll barrel length is longer than that when the exit side angle α ₂ is larger than the entrance side angle α _1. Becomes relatively long. Therefore, α ₁ does not exceed α ₂ .

Next, the operation of this embodiment will be described. In the structure in which the water injection port 34 and the lubricant injection port 35 are provided at the tip of the pusher 30, the injection header 33 having a diameter smaller than the pipe inner diameter is provided almost fixedly at the tip of the pusher 30, and the injection header 33 is provided with these. A water injection port 34 and a lubricant injection port 35 are provided, and a supply pipe for supplying water and a lubricant from the pusher 30 to the water injection port 34 provided on the injection header 33 and the lubricant injection port 35 is extended. It will be made to exist. Therefore, in this case, in the pipe rolling mill 20 (without intentionally lengthening the rolling line) and with a simple piping structure, water and lubricant are not clogged or leaked to the inner surface of the pipe immediately before rolling. A stable supply is possible.

With the above, water and lubricant can be stably supplied in the required amounts without being clogged or leaking in the supply pipe system, and the occurrence of inner surface flaws in the pipe can be prevented. Further, the required amount of pipe expansion can be obtained without the water leaking to the inner surface of the pipe cooling the rolled material and increasing its deformation resistance.

As described above, the water and the lubricant are supplied to the material to be rolled in the pipe rolling mill 20, and when the special descaler is provided in front of the rolling mill, the temperature drop of the material to be rolled is compensated when the rolling line length becomes long. No need for high temperature reheating. For this reason, it is possible to make the inner surface of the pipe after rolling good without excessive generation of the inner scale of the pipe due to reheating at high temperature.

The present invention was carried out as described in (1) to (4) below. (1) In the device 1 of the present invention, only the water injection port is provided at the tip of the pusher, and in the device 2 of the present invention, both the water injection port and the lubricant injection port are provided at the tip of the pusher. The device 2 of the present invention
Then, granular graphite (150gr / element tube) was sprayed as a lubricant together with water. In the conventional apparatus 1, the independent descaler as described above is provided immediately before the four tube expanding and rolling machines. In the conventional device 2, the plug of the tube rolling mill is provided with the injection nozzle as shown in FIG.

(2) The material to be rolled is carbon steel, the size before rolling is 90 to 190 mm in diameter, the wall thickness is 15 to 30 mm, and the size after rolling is diameter
The thickness was 120 to 250 mm and the wall thickness was 8 to 20 mm. The rolling roll was a cone type roll, the gorge diameter D _R = 1200 mm, the advance angle β = 15 degrees, and the crossing angle γ = 20 degrees.

(3) Table 1 shows the reheating temperature applied to the material to be rolled in the reheating furnace installed on the inlet side of the tube rolling mill and the outlet temperature of the tube rolling mill.

[0035]

[Table 1]

(4) As a result of rolling 300 hollow shells in each of the devices 1 and 2 of the present invention and the conventional devices 1 and 2, the clogging frequency of the pipe to the injection port and the maintenance time are shown in Table 2. .

In Table 2, the conventional apparatus 1 has a large amount of scale generated due to the high temperature reheating and a large inner surface roughness. Further, the conventional device 2 has a large variation in the inner surface roughness due to the occurrence of the clogging of the piping. On the other hand, in the device 1 of the present invention, the inner surface roughness was improved, and in the device 2 of the present invention, the inner surface roughness was further improved.

[0038]

[Table 2]

The embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific structure of the present invention is not limited to this embodiment, and changes in design within the scope not departing from the gist of the present invention can be made. Even if it exists, it is included in the present invention. For example, only one of the water injection port and the lubricant injection port may be provided at the tip of the pusher.

[0040]

As described above, according to the present invention, it is possible to stably supply water and / or a lubricant to the inner surface of the pipe immediately before rolling with a simple structure and improve the inner surface properties of the pipe.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of a tube rolling mill.

FIG. 2 is a schematic diagram showing a rolling start state by the pipe rolling mill.

FIG. 3 is a schematic diagram showing a state during rolling by a pipe rolling mill.

FIG. 4 is an enlarged view of a main part of FIG.

FIG. 5 is a schematic diagram showing the effect of the present invention.

FIG. 6 is a schematic view showing a conventional example.

[Fig. 7] Fig. 7 is a diagram showing a situation in which a biting failure, a tail slipping failure, and a hollow tear due to flaring occur when tube rolling is performed while changing the wall thickness reduction rate and the tube expansion rate.

[Explanation of symbols]

 10 Tube Expansion Roller 20 Tube Expansion Roller 21 Rolling Roll 22 Plug 30 Pusher 33 Injection Header 34 Water Injection Port 35 Lubricant Injection Port

Claims (1)

[Claims] 1. A pipe rolling mill in which a pair of rolling rolls are inclined with respect to a pass line at a constant advance angle, and a plug is arranged between the pair of rolling rolls, and a hollow pipe rolling mill is provided. In a seamless pipe expanding and rolling apparatus having a pusher for biting the raw pipe, a water injection port for descaling the inner surface of the hollow raw pipe, and / or the inner surface of the hollow raw pipe, at the tip of the pusher. A seamless pipe expanding and rolling apparatus, characterized in that a lubricant injection port for lubricating the pipe is provided.