JPH079013A - Equipment for manufacturing seamless steel tube - Google Patents

Abstract

PURPOSE:To bore billets having different kinds of major diameters without injuring the outer surfaces by providing at least a pair of guide rolls having a concaved surface each which can adjust interval, crossing angle and revolving speed on the outlet side of a borer. CONSTITUTION:Bar stagers 7a,... retreat successively in accordance with the adreacing of the billets 2 to release the restriction of a mandrel bar 5 and a torsion generates in a plug 6 because an unrestricted part of the mandrel bar 5 becomes longer. A bored part of a bar body 2a is also twisted by the torsion of the plug 6 but since the bar body 2a is held by guide rolls 8a, 8b on the outlet side of the borer 1, no torsion generates therefore, promotion of the torsion of the plug 6 due to the torsion of the bar body 2a is restricted. Consequently, problems such as waviness, bending or thickness deviation of the bar body 2a in the boring stage do not occur, the yield can be improved and a high-accuracy seamless steel tube can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seamless steel pipe manufacturing facility, and more particularly, to a seamless steel pipe manufacturing facility equipped with a means for preventing undulation and bending of a tubular body.

[0002]

2. Description of the Related Art In a seamless steel pipe production line, a billet heated in a heating furnace is first perforated by a perforator into a thick pipe. In this case, in order to eliminate the uneven thickness of the pipe (thickness variation in the radial direction), the center of the billet and the plug must match the center of the drilling machine. It is necessary to fix the position of.

FIG. 2 is a schematic view showing an example of a conventional punching machine. In the figure, 1 is a punching machine. 2 is a billet heated in a heating furnace, 4a and 4b are large drum-shaped piercer rolls installed to intersect, and the billet 2 is moved up and down (or left and right).
Then, the billet 2 is subjected to repetitive rotational compression to give a Mannesmann effect (internal collapse effect) to the center of the billet 2 and to advance in the direction of arrow a.

5 is a mandrel bar whose one end is fixed,
A plug 6 is attached to the tip, and the plug 6 is attached to the center of the billet 2 which is brittle due to the Mannesmann effect.
Then, a hole 3 is formed in the center of the billet 1 as the billet 1 advances. 7a, 7b, ... are bar stagers that restrain the mandrel bar 5 in order to prevent the mandrel bar 5 from bending, and a plurality of bar stagers are installed in the length direction. When the portion of the billet 2 that has been pierced is referred to as a tubular body), the tubular body 2a is sequentially withdrawn as it approaches.
Pass through.

[0005]

In the conventional punching machine 1 as described above, as the drilling of the billet 2 proceeds, the bar stager 7a,
Since the restraint of the mandrel bar 5 by 7b, ... Must be released, when the drilling progresses to almost the middle part of the billet 2 in the longitudinal direction, the mandrel bar 5 becomes to have the degree of freedom in the radial direction of the billet 2. , The plug 6 shakes.

Therefore, as shown in FIGS. 3 and 4, the perforated portion of the tube body 2a is swung more greatly, which further promotes the swing of the plug 6. As a result, not only undulations and bending occur in the tubular body 2a, but also as shown in FIG.
The thickness formed by the outer diameter of the tubular body 2a and the hole 3 is t ₁ on one side and t ₂ on the other side, so that t ₁ <t ₂ and uneven thickness occurs. The undulations and bends have various influences on the subsequent steps, and the uneven thickness is not eliminated even after the final step, which has been a factor of reducing the product accuracy and the yield.

The present invention has been made to solve the above problems, and obtains a seamless steel pipe manufacturing facility capable of preventing the undulation and bending of the pipe body during the perforation process and improving the product accuracy and the yield. It is intended for.

[0008]

A seamless steel pipe manufacturing facility according to the present invention is provided with at least a pair of hourglass-shaped guide rolls capable of adjusting a gap, a crossing angle, and a rotation speed on an exit side of a punching machine for punching a billet. Is installed.

[0009]

Operation As the billet drilling progresses, the restraint of the mandrel bar by the bar stager is released from a position near the exit side of the drilling machine, but when the drilling progresses to almost the middle of the billet length, the mandrel bar The degree of freedom is increased in the radial direction of the billet, causing runout in the plug.
The runout of the billet also tries to be swung around due to the runout of the plug, but since the billet is held by the guide rolls on the exit side of the punching machine, no runout occurs, and the runout of the plug due to runout of the billet is promoted. Can be suppressed. As a result, the problems of waviness and bending of the tubular body or uneven thickness in the drilling process do not occur.

[0010]

1 is a schematic view of an embodiment of the present invention. In the figure, 1 is a punching machine, 2 is a billet, 4a and 4b are piercer rolls, and 5 is a mandrel bar having a plug 6 at the tip,
7a, ... Are bar stagers, which are the same as the conventional example described in FIG. 8a and 8b are installed on the exit side of the punching machine 1 so as to intersect with each other vertically, and are a pair of hourglass-shaped guide rolls that guide the tube body, and are spaced so as to accommodate all outer diameters of the billet 2 to be punched. , The crossing angle and the rotation speed can be adjusted.

Next, the operation of the present invention configured as described above will be described. The billet 2 heated in the heating furnace is a punch 1
Then, the piercer rolls 4a and 4b are pressed and rotated, and the Mannesmann effect is given to the central portion of the piercer rolls 4a and 4b to proceed in the direction of arrow a. Then, the center portion fragile due to the Mannesmann effect hits the plug 6 of the mandrel bar 5 which is restrained by the perstager 7a, ... And continues to move forward to form the hole 3 in the center portion.

As the billet 2 advances, the bar stagers 7a, ... Retreat in sequence to release the restraint of the mandrel bar 5, and when the drilling progresses to almost the middle portion of the billet 2, the mandrel bar 5 moves. Since the unconstrained portion becomes long, the mandrel bar 3 has a degree of freedom in the diameter direction of the billet 2, and the plug 6 swings.

The perforated portion of the tubular body 2a tends to be swung by the deflection of the plug 6, but since the tubular body 2a is held by the guide rolls 8 and 8b on the exit side of the perforator 1, a deflection occurs. Therefore, the acceleration of the shake of the plug 6 due to the shake of the tubular body 2a can be suppressed.
As a result, there is no problem of waviness or bending of the tubular body 2a or uneven thickness in the drilling step, and the yield is improved,
It is possible to manufacture a highly accurate seamless steel pipe.

A conventional punching machine as shown in FIG. 2 has an outer diameter of 2
When a hole having a diameter of 150 mm was punched in a billet having a diameter of 10 mm, the cut length of the front crop was about 750 mm due to undulations and bending. On the other hand, according to the present invention, when the billet was perforated under the same conditions as described above, the cutting length of the front crop due to the swell and the bend was only 250 mm.
It was confirmed that the yield and the product accuracy were significantly improved.

In the above description, an example in which a pair of upper and lower guide rolls 8a and 8b are installed on the exit side of the punching machine 1 is shown.
You may install a pair of guide rolls on the left and right,
A pair of guide rolls may be installed on the left and right at the same position, or a total of two pairs of guide rolls, or a pair of guide rolls may be installed on the top, bottom, left and right at different positions.

[0016]

As described in detail above, according to the present invention, at least a pair of hourglass-shaped guide rolls having adjustable intervals, crossing angles and rotational speeds are installed on the exit side of a punching machine, and the billet of the punched part is installed. Since the plug is held, even if the plug advances and the plug vibrates, the perforated portion is not swung, so that the vibration of the plug due to the vibration of the tubular body can be suppressed. For this reason, it is possible to prevent the tube body from waviness and bending in the drilling step, and further to prevent uneven thickness from being generated, so that the yield is improved and a highly accurate seamless steel tube can be manufactured.

Further, since the above-mentioned guide roll can adjust the interval, the crossing angle and the number of revolutions, it is not necessary to change the guide roll even if the outer diameter of the billet changes, and the speed of the billet on the exit side of the punching machine can be adjusted. If these are adjusted correspondingly, it is possible to perforate billets of various outer diameters without damaging the outer surface.

[Brief description of drawings]

FIG. 1 is a schematic view of an example of the present invention.

FIG. 2 is a schematic view of a conventional punching machine.

FIG. 3 is a diagram illustrating the operation of a conventional punching machine.

FIG. 4 is an enlarged view of a portion A of FIG.

[Explanation of symbols]

 1 punching machine 2 billet 2a tube body 3 holes 4a, 4b piercer roll 5 mandrel bar 6 plug 7a, 7b bar stager 8a, 8b hourglass-shaped guide roll

Claims (1)

[Claims] 1. A seamless steel pipe manufacturing facility including a perforator, wherein at least a pair of hourglass-shaped guide rolls capable of adjusting a gap, a crossing angle, and a rotation speed are installed on an exit side of the perforator. Seamless steel pipe manufacturing equipment.