JPS60137511A - Plug for manufacturing seamless pipe - Google Patents

Abstract

PURPOSE:To provide wear resistance, erosion resistance, and seizure resistance, etc. to a mandrel and to improve its service life by providing a ceramic tip part to a body part of the mandrel made of low-alloy steel. CONSTITUTION:A tip parr 1 of mandrel is made of a ceramic material, and its body part is made of a low-alloy steel provided with an oxidized-layer forming heat-treatment. The joining of the parts 1 and 2 is performed by either of two methods, that is an adhesive method, by forming a projecting fitting-part at the tip part 1, or a shrinkage fitting method. In the adhesive method, a ZrO3 adhesive is coated on the joining part of tip part 1 and body part 2, but other adhesives having a >=1,000 deg.C heat resisting temperature are also available.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the invention of a plug for manufacturing seamless pipes, which prevents damage such as melting or burning in the core metal used for Mannesmann drilling of seamless pipes. It dramatically improves the durability of the core metal as a ceramic material with severe wear resistance, surface 1 melting f-C, and seizure resistance, while also stabilizing the inner surface. Trying to get approval for nitrogen 1-
It is something that

4. A man's practice to make white cum is made by rolling a round piece of steel heated in a heat furnace into two barrel-shaped rolls (σ month).
(A hole is made in the center of a round piece of steel by the rotational V3% effect produced by biting the round steel piece and the core metal attached to the tip of the mandrel, but the surface of the core metal used in this situation Because it is exposed to high temperatures and extremely high pressure, it often causes surface abrasion, melting, or seizure, which adversely affects the inner quality of the resulting hollow piece. Various studies have been conducted on the material of gold, its heat treatment method, and the method of cooling the surface of the core metal.The core metal widely used today is 0.3 C-3Cr-INl low alloy steel. By performing heat treatment as shown in Publication No. 82230, an oxidized layer is formed on the surface of the core metal, thereby extending the life of the core metal.However, the tip M portion of the core metal as described above is When drilling ordinary steel using the current core metal, heat treatment of the above-mentioned degree can produce significant effects due to extremely red-hot conditions and high pressure, resulting in significant abrasion, grinding, and seizure. The tip of the core bar starts to wear out after several to tens of drillings, and a worn part 11 as shown in FIG. 2 appears on the newly manufactured core bar 10 as shown in FIG. This occurs over a long period of time, and the service life is almost always determined by the extreme wear and tear of the tip.Also, when drilling into high alloy materials such as N1. Even if the side surface of the core bar 10 is sound after the hole is drilled, the tip of the core bar 10 may be seize up or the exposed part 1 may be damaged.
The state of 2 is very strong, and the longevity of the core metal is 5 even if it is long.
The strength is the same, and in some cases, it is often necessary to stop using it after just one use. Furthermore, such a core metal 10
Although the shape of the tip is ideally designed for the metal flow of the material during drilling, it is difficult to maintain the ideal metal flow due to wear and tear on the tip of the core metal during drilling. I ended up not being able to do it.
Furthermore, as the reduction ratio at the tip of the core metal increases until the material comes into contact with the tip of the core metal, the possibility of rotary forging cracking (IJJ) increases, leading to a reduction in the cost of inner parts of the hollow piece.

The present invention was devised after repeated studies in view of the above-mentioned circumstances, and proposes that only the tip of the low-alloy steel core be made of a ceramic material. That is, the present inventors have considered making the core metal a wear-resistant material as a countermeasure to the problems with conventional core metals as described above, and have developed materials such as heat-resistant alloys that can withstand the harsh environments that core metals are exposed to. It is thought that ceramic materials with far superior properties are suitable, and the entire core bar as shown in Figure 1 is
(I tried drilling holes made of various ceramic materials including 3N4, but the core metal fractured during drilling in all cases.However, the cause of such core metal fracture was the mandrel crack at the rear end of the core metal.) The shape of the core metal is complex, such as the attachment part, and there are parts that are prone to stress concentration, and of course, it is thought that making the entire core metal ceramic increases the probability of breakage due to dimensional effects.Moreover, this ceramic is an inorganic material. Since it is manufactured by sintering powder in a heating furnace, there is no actual seam**
It is difficult to make the entire large-diameter core metal used in the manufacturing process with this ceramic (at least with the current ceramic manufacturing equipment).Therefore, after further consideration, we decided to make only the tip part as a low-alloy ceramic as shown above. The core metal body is made of steel and has a 5J capacity for loading and unloading, and the ceramic material is Si 3 j'J 4, stc, zro,;
There are various types of materials, all of which have heat resistance and low affinity with metals, such as heat resistance and low affinity with metals at low temperatures (at still temperatures). y
I dreamed of being on the verge of G1, and I was intoxicated by the suitable material. However, one drawback of ceramics is that they have low tensile fracture strength.
Compression Lr, such as the tip of the core metal: Control of force [1' In the force field, this defect hardly becomes a problem, and the volume is small and the probability of breakage is significantly reduced. Together with this, its characteristics can be fully demonstrated. The general structural relationship is as shown in Fig. 4, where a ceramic tip 1 is attached to the tip of a core metal base 2 made of low alloy steel, and a mandrel mounting hole 3 is formed at the tail end of the main body 2. The size of the tip 1 was determined by taking into consideration the wear of the tip of the core metal under the condition of two holes in each conventional low alloy steel core metal such as 0.3 C-3Cr-I Ni system. It may be made of ceramic, and its length is 1/10 to 1/4 of the length of the entire core metal. Further, the core metal matrix portion 2 is made of the conventional low alloy steel such as the above-mentioned 0.3 C-3Cr-INi series heat-treated to form an oxide layer on its surface.

For joining the ceramic tip 1 and the metal core base portion 2, a careless method such as baking or bonding with an adhesive may be adopted, as will be described in detail in the embodiments to be described later.

I mentioned above 57. c The core metal according to the present invention has a ceramic material at the tip that has a permanent lifespan due to the corrosion resistance, corrosion resistance, and fire resistance. As a result, there has been a dramatic increase in the number of special core metals (100
times) are obtained. Moreover, since the tip of the core metal does not wear out, the drilling condition at the tip of the core metal is always constant.
Needless to say, as a result, a hollow piece with uniform and good inner surface properties and quality can be obtained.

The specific manufacturing example 1 according to the present invention is explained as follows. With a core metal as shown in Fig. 4, the length of this base part 2 is 64 mm and the tip is 20 mm,
The tip part 1 is made of commercially available 843N4 ceramic, and the base part 2 is made of 0,3C-3C which has been subjected to oxidation)-formation heat treatment.
Made from r-INI low alloy steel. The specific mechanical properties of the ceramic are shown in Table 1 below.

Table 1 The joining of the tip end 1 and the base body part 2 is by an adhesive method in which a fitting protrusion 1 m in length is formed on the tip end 1 as shown in Fig. 5, and in Fig. 6. As shown, the fitting protrusion 1b has a length of 20 mm.
The former adhesive is a ZrO3-based adhesive applied to the joint between the tip part 1 and the base part 2, but an adhesive that can withstand temperatures of over 1000°C If so, it goes without saying that it may be something else. In addition, the firing dimensional tolerance for the latter part is selected taking into account the difference in thermal expansion coefficient between the tip part 1 and the base part 2, and the rise in hot water temperature of the core metal during drilling, and the firing temperature is set at the same temperature as that of the tip part 1. Thermal shock resistance temperature (
700°C) or less. According to the results of examining the condition of these core metals after conducting a hot model drilling test, all of the core metals are completely sound, and there is no wear or seizure, etc., particularly at the tips. Further, visual inspection of the inner surface of the hollow piece revealed that there were no inner defects, the inner surface was in very good condition, and it was still usable even after being punched 100 times.

Note that the device according to the present invention as described above employs not only the Mannesmann drilling described above, but also the tips of each of the punches for hot extrusion, the core bar for press roll drilling (PPM), the punch for direct piercing, etc., made of ceramic. Furthermore, it is also possible to apply ceramics to core metals for other rolling mills such as the Erogota Plug Mill and the Leela Gin.

According to the present invention as explained above, by providing a ceramic tip to the low-alloy core metal base body, extremely excellent wear resistance, melting resistance, seizure resistance, etc. can be achieved in one piece. It is possible to provide a core metal that does not cause the occurrence of defects such as 41, etc., that is, not only can the life of the core metal be greatly improved, but also the inward product 11 can stably and appropriately spin a good hollow piece. This is a vague defense of its effectiveness from an industrial perspective.

[Brief explanation of drawings]

The drawings show the technical contents of the present invention, and FIG. 1 is a side view of a conventional core metal, FIG. The figure is a side view of the seizure and melting state after the drilling process for the high alloy material, and Figure 4 is a 1llll of the core metal according to the present invention.
FIG. 5 is a side view showing the disassembled state of the core metal of the present invention using the adhesion method, and FIG. 6 is a side view showing the disassembled state of the core metal of the present invention using the firing method. However, in these drawings, 1 is a ceramic tip;
Reference numeral 2 indicates a core metal base body, 1a and 1b are fitting protrusions, and 3 is a mandrel mounting hole. Patent applicant: Nippon Kokan Co., Ltd. Inventor: Toyodo Mihara Soldering device: Tatsube No. A No. <, -Kuniri no No. ρ

Claims (1)

[Claims] A plug for seamless production that is characterized by having a ceramic tip added to the steel core base.