JPH11123411A - Tool for piercing press roll and method for piercing press roll using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piercing tool for press rolls with which a good inside surface is obtained without generating burning on a material to be pierced and which is excellent in resistance to cracking and piercing method of the press roll using the same. SOLUTION: In the piercing tool 10 for press rolls provided with a plug 11 in the front of a mandrel bar 13 for piercing and drawing the material to be pierced into a seamless steel tube attaching to a press roll piercing machine, an annular ring 12 having the outside diameter D, larger than the outside diameter Dp of the plug 11 is arranged at the rear of the plug 11. It is better that the material of this annular ring 12 is one having heat resistance and wear resistance such as ceramic and cermet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a press roll drilling tool having a plug and a press roll drilling method using the same, which is used for producing a seamless steel pipe from a material to be drilled such as a square billet.

[0002]

2. Description of the Related Art Various stainless seamless steel pipes manufactured by the hot extrusion method represented by the Eugene Sejournet method have recently been rolled by the mandrel mill method and the plug mill method which have higher productivity than the hot extrusion method. Manufactured by law. As one of the rolling methods, a press roll drilling method is well known, and a 3% Cr-1Ni-based low alloy steel is used as a material of a plug constituting a press roll drilling tool used in the punching method. In order to ensure heat insulation, a treatment for forming an oxide scale such as Fe ₃ O ₄ or FeO on the surface layer by heat treatment is performed.

[0003] In order to extend the life of the plug for press roll perforation, studies have been made on the use of ceramics as a material having improved plug shape and excellent seizure resistance and heat resistance. For example, a press roll drilling tool 4 shown in FIG.
0, the ceramic plug 41 is directly screw-connected to the mandrel bar 42, that is, the female screw portion 43 provided on the base end side of the plug 41 and the male screw portion 44 formed at the distal end of the mandrel bar 42. It has an integral structure by screwing. The outer diameter D _p of the plug 41 (46.5 m
m) is the outer diameter D _m (45.5 mm) of the mandrel bar 42
It is formed 1 mm larger than that. Japanese Patent Laid-Open No. 60-372 discloses a method of specifying the shape of a plug so that a metal flow near a plug of a material to be pierced does not damage the tip of the plug.
No. 04 has proposed this. When carbon steel is perforated by this method, the life of the plug is 600 or more, and there is no problem.

[0004]

However, even if such an improvement is made, if the material to be perforated has a higher deformation resistance than carbon steel, and if stainless steel is hardly oxidized on the surface, it is perforated by press roll perforation, The plug 41 is melted at an early stage, and as a result, seizure flaws are generated on the inner surface of the stainless steel pipe. For example, SUS420J1 steel or SUS30
The life of the plug at the time of drilling of No. 4 is several. Also, when ceramics or cermets having excellent seizure resistance and heat resistance are applied to the plug, a good inner surface can be obtained without seizure of the material to be pierced, but there is a problem that the plug is broken. The present invention has been made in view of such circumstances, and provides a good inner surface without seizure on a material to be drilled, and a press roll drilling tool excellent in crack resistance and using the same. An object of the present invention is to provide a press roll perforation method.

[0005]

According to the present invention, there is provided a semiconductor device comprising:
The press roll drilling tool according to the present invention is mounted on a press roll drilling machine, and drills a material to be drilled into a seamless steel pipe and pulls out the same. In a press roll drilling tool provided with a plug at the end of a mandrel bar, An annular ring having an outer diameter that is larger than the outer diameter of the plug is disposed. According to a second aspect of the present invention, there is provided a press roll perforating tool according to the first aspect, wherein the annular ring is fitted to a fitting portion connected to a perforated portion of the plug. According to a third aspect of the present invention, there is provided a press roll drilling tool according to the first or second aspect, wherein the material of the annular ring has heat resistance and wear resistance such as ceramics or cermet.

According to a fourth aspect of the present invention, in the press roll drilling method in which a material to be drilled is drilled into a seamless steel pipe with a plug and drawn out, the inner surface of the drilled material drilled by the plug is plugged. Flared by an annular ring disposed outside of the plug and having an outer diameter greater than the outer diameter of the plug. According to a fifth aspect of the present invention, in the press roll perforation method according to the fourth aspect, the material of the annular ring has heat resistance and wear resistance such as ceramics or cermet.

The present inventors have reached the present invention by the method described below. In order to investigate the cause of cracking of the ceramic plug 41 when using the press roll drilling tool 40 used in the conventional press roll drilling method shown in FIG. 3, the press roll drill was stopped halfway through the drilling. The state of the plug 41 was investigated. As a result, plug 4
No. 1 was not broken at the time of perforation. This is considered to be due to the fact that the stress generated in the plug 41 at the time of punching the press roll is mainly compression. Therefore, when the plug 41 is pulled out after the perforation, the friction of the plug 41 in the direction opposite to the perforation direction acts on the surface of the plug 41 that is in contact with the inner surface of the perforated material. Was found to be caused by the tensile stress generated in the steel.

Therefore, in order to prevent the plug 41 from cracking,
As a result of intensive studies on a method in which the plug 41 is not subjected to tensile stress when the plug 41 is pulled out, the press roll drilling tool 10 as shown in FIG. 1 was able to be invented. In the press roll piercing tool 10, the rear end side of the ceramic plug 11, a large annular ring 12 than the outside diameter D _p of the outer diameter D _r plug 11 provided, the annular ring 1
By expanding the inner surface of the material to be pierced by 2, the plug 11 is prevented from contacting with the material to be pierced when the plug 11 is pulled out, so that no frictional force acts on the plug 11.
A tensile stress generated in the axial direction can be prevented from being generated.
In order to prevent the tensile stress from acting on the annular ring 12 when the plug 11 is pulled out, the annular ring 12 and the mandrel bar 13 are not connected with a screw as in the related art, The ring 12 is fastened to the mandrel bar 13. The outer diameter D of the ring 12
_r, considering the bending of the mandrel bar 13 during drilling, it is desirable to increase or 1mm than the outer diameter D _p of the plug 11.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention. Here, FIG. 1 is a cross-sectional configuration diagram of a press roll drilling tool according to an embodiment of the present invention, and FIG. 2 is a cross-sectional configuration diagram of a modified example of the press roll drilling tool. In a press roll drilling tool 10 according to an embodiment of the present invention, a plug 1 for drilling a material to be drilled is provided between an end of a mandrel bar 13 and an annular ring 12.
1 for fastening the mandrel bar 13 to the mandrel bar 13 with screws
4 is provided. The details will be described below.

The plug 11 is made of ceramics (for example, silicon nitride ceramics) similarly to the conventional plug 41, and has a female screw portion 16 screwed with a male screw portion 15 formed at one end of the joint 14 on the base end side. Is formed, and the outer diameter D _p (44.5 mm in the present embodiment) is equal to the outer diameter D of the annular ring 12.
_r (46.5 mm in the present embodiment) is 1 mm or more smaller. The annular ring 12 is also made of ceramics (for example, silicon nitride ceramic) like the plug 11, and is disposed between the tip of the mandrel bar 13 and the annular surface on one side of the central disk portion 17 of the joint 14, An insertion hole 19 is formed at the center of the annular ring 12 so as to be inserted into the fitting portion 18 of the joint 14. As shown in FIG. 1, the annular ring 12 has an outer diameter Dj (43.5 mm in the present embodiment) of the center disk portion 17 of the joint 14 and an outer diameter _Dm (45.5 mm in the present embodiment) of the mandrel bar 13. 5 mm) are tapered at both ends so as to connect smoothly.

The joint 14 is made of, for example, SKB61 (JIS).
A male screw part 15 screwed into the female screw part 16 of the plug 11, and a central circle inserted between the annular surface at the base end of the plug 11 and the annular surface on the other side of the annular ring 12. Plate part 1
7 and a fitting portion 1 fitted into the insertion hole 19 of the annular ring 12
8 and a male screw portion 21 that is screwed into a female screw portion 20 formed on the distal end side of the mandrel bar 13 are integrally formed in this order.

FIG. 2 is a sectional view showing a modification of the press roll punching tool according to one embodiment of the present invention. The press roll drilling tool 30 of the modification is characterized in that the joint 14 is omitted as compared with the press roll drilling tool 10. That is, the press roll punching tool 30 includes a plug 31 having a punched portion 32 at the tip, and an annular ring 12 disposed between the punched portion 32 and the mandrel bar 13.

The outer diameter of the perforated portion 32 near the abutment with the annular surface on the other side of the annular ring 12 has a plug 11 shown in FIG.
The outer diameter of the joint 14 is the same as that of the center disk 17 of the joint 14. On the proximal end side of the plug 31, a fitting portion 33 inserted into the insertion hole 19 of the annular ring 12, and a male screw portion 34 screwed into the female screw portion 20 formed on the distal end side of the mandrel bar 13.
Are connected to the perforated portion 32 in this order. Outer diameter D _p of the perforated portion 32 of the plug 31 is the same as the outer diameter D _p of the press roll piercing tool 10, the axial length of the piercing portion 32 of the plug 31, the plug in a press roll piercing tool 10 11 And the center disk portion 17 of the joint 14 plus the axial length. The press roll punching tool 30 is different from the press roll punching tool 10 in that
Since the joint 14 is omitted, the structure is simple, so that processing such as threading is easy, and replacement is easy. Further, the strength of the perforated portion 32 of the plug 31 can be made larger than that of the plug 11.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A press roll punching tool 10 having the dimensions shown in FIG.
An embodiment in which a material to be pierced is pierced and drawn out of a seamless steel pipe will be described. As a material to be perforated, a square piece of JIS SUS420J1 steel having a side length of 80 mm and a length of 650 mm was heated to 1250 ° C., and then perforated with a press roll boring tool 10 at 1100 ° C. At that time, for the purpose of comparison, drilling was also performed using the conventional press roll drilling tool 40 shown in FIG. The materials of the plugs 11 and 41 and the annular ring 12 were silicon nitride ceramics. As a result, when the conventional press roll punching tool 40 having the dimensions shown in FIG. 3 is used, the plug 41 is broken,
At the time of pulling out, a part of the plug 41 remained in the material to be perforated.
On the other hand, the press roll drilling tool 10 according to the present embodiment
In case of using the inner surface of the perforated material, since the widened by an annular ring 12 having an outer diameter D _p larger outer diameter D _r of the plug 11, the withdrawal time also without the plug 11 is broken, and the The inner surface of the perforated material was also good.

In the present embodiment, stainless steel has been described as the material to be perforated, but other materials may be used. Although the material of the annular ring is ceramics, the material is not limited to this, and a material having heat resistance and abrasion resistance such as cermet can be used.

[0016]

In the press roll drilling tool according to the first to third aspects and the press roll drilling method according to the fourth and fifth aspects, the inner surface of the material to be drilled by the plug is arranged behind the plug. In addition, since it can be expanded by an annular ring having an outer diameter larger than the outer diameter of the plug, frictional force in the direction opposite to the drilling direction does not act on the surface of the plug that is in contact with the inner surface of the material to be drilled at the time of drawing. Further, it is possible to prevent the occurrence of cracks on the surface of the plug due to the tensile stress generated in the axial direction as in the related art. In particular, in the press roll punching tool according to the second aspect, since the annular ring is fitted to the fitting portion connected to the punched portion of the plug, a tensile stress is generated also on the surface of the annular ring at the time of removal. This prevents cracks on the surface of the annular ring. Further, since the female screw portion is not formed in the perforated portion of the plug, the strength of the perforated portion of the plug can be increased as compared with the related art. In the press roll drilling tool according to the third aspect and the press roll drilling method according to the fifth aspect, since the material of the annular ring has heat resistance and wear resistance such as ceramics or cermet, the material to be drilled is stainless steel. Even in the case of high strength such as steel, the occurrence of cracks can be prevented.

[Brief description of the drawings]

FIG. 1 is a sectional configuration diagram of a press roll punching tool according to an embodiment of the present invention.

FIG. 2 is a sectional configuration diagram of a modified example of the press roll punching tool.

FIG. 3 is a sectional configuration diagram of a press roll punching tool according to a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Press roll drilling tool 11 Plug 12 Annular ring 13 Mandrel bar 14 Joint 15 Male screw part 16 Female screw part 17 Central disk part 18 Fitting part 19 Insertion hole 20 Female screw part 21 Male screw part 30 Press roll drilling tool 31 plug 32 piercing part 33 fitting part 34 male screw part

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Seiji Ishibashi 1-1-1, Hibata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka New Nippon Steel Corporation Yawata Works

Claims (5)

[Claims] 1. A press roll drilling tool provided with a plug at the end of a mandrel bar, which is attached to a press roll punching machine and drills and pulls out a material to be drilled into a seamless steel pipe. A press roll drilling tool, wherein an annular ring having an outer diameter larger than the outer diameter is arranged. 2. The press roll drilling tool according to claim 1, wherein the annular ring fits into a fitting portion connected to a drilling portion of the plug. 3. The press roll drilling tool according to claim 1, wherein the material of the annular ring has heat resistance and wear resistance such as ceramics or cermet. 4. A press roll perforation method for perforating and drawing a material to be perforated into a seamless steel pipe with a plug, wherein the inner surface of the perforated material perforated by the plug is disposed behind the plug. A press roll perforation method characterized by spreading by an annular ring having an outer diameter larger than the outer diameter of the press roll. 5. The press roll perforation method according to claim 4, wherein the material of the annular ring has heat resistance and wear resistance such as ceramics or cermet.