JPH07204711A - Piercer bar cap for assel mill - Google Patents

Abstract

PURPOSE:To reduce frequency of exchanging a piercer bar cap, manpower and cost by preventing wear of the abutting surface of core metal of a piercer bar cap of an assel mill. CONSTITUTION:In the piercer bar cap 1 provided with a columnar projection 6 on whose tip end the core metal 7 of hollow shell shape is mounted covering the projection, a core metal supporting part 2 by which the rear end face of core metal is supported around the base bottom part of the projection and a screw part 5 with whose rear part a mandrel bar is connected by a screw, a buried build-up part 3 of an alloy whose hardness is higher than the hardness of piercer bar cap is provided on the abutting face of core metal supporting part 2 and the core metal is supported on the build-up part. A stellite of Co-Cr- W alloy is used as the alloy harder than the bar cap 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a contact surface with a rear end surface of a core metal around a base of a projection at a tip of a pier server cap of an assel mill for manufacturing a steel pipe or the like.

[0002]

2. Description of the Related Art In a piercer for manufacturing a steel pipe or the like, a pier server cap for supporting a core metal is usually SKD-61.
Etc. made of steel. On the other hand, as the core bar for piercing the steel material, low alloy cast steel such as 2Cr-1Ni is often used. By the way, at the time of manufacturing a steel pipe by piercing, the rear of the pier server cap is cooled by the cooling water circulating inside the mandrel bar, but the front is normally 200 to 3
When the temperature is raised to 00 ° C and the core metal is subjected to severe pressure during processing, and especially the contact surface that supports the core metal is subjected to severe repeated impact friction from the core metal, it gradually wears and the rear end of the core metal As it goes in, the directional stability of the core becomes worse,
Then, the inner surface of the cored bar and the bar cap projections come into unstable contact with each other, so that the projections are broken or the inner surface of the pierced material is flawed.
Therefore, the peer server cap must be replaced early, which complicates the work and increases the cost.

[0003]

The problem to be solved is to prevent abrasion of the contact surface of the assel mill of the peer server cap with the core metal, to extend the service life of the peer server cap, and The less frequent replacement, the less labor and cost.

[0004]

According to the present invention, the metal material of the contact surface with the core metal of the peer server cap is changed to a steel material such as SKD-61 of the peer server cap, and excellent in high temperature strength and durability. A hard alloy, for example, Stellite, which is a Co-Cr-W type alloy, can withstand impact friction from a cored bar made of a harder material such as a low alloy cast steel such as 2Cr-1Ni.

Therefore, the means for solving the problems are
In the pier server cap, which has a cylindrical protrusion at the tip for covering and mounting a hollow cannonball-shaped core metal, and a screw portion at the rear for screwing and connecting the tip of the mandrel bar, the base of the protrusion at the tip On the contact surface with the rear end surface of the core metal around the, the embedded portion of the alloy harder than the steel material of the bar cap is provided, and as the alloy harder than the steel material of the bar cap, the stellite alloy (Co-Cr-W Alloy).

[0006]

According to the present invention, the contact surface with the rear end surface of the core metal around the base of the columnar projection for covering the tip with the hollow shell-shaped core metal is annularly shaved to have a depth of 5 mm and a width. A groove of about 7 mm is formed, and a hard alloy excellent in high temperature strength and durability such as Stellite which is a Co—Cr—W alloy is built up in the groove. Therefore, during the piercing process, even if the contact surface is subjected to severe impact friction from the core metal and is exposed to a high temperature, the contact surface is not worn and the above-mentioned trouble does not occur. Note that, as is commonly done in the build-up of stellite, if nickel is deposited in the groove as a base material, the stellite can be built-up well.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS. As shown in Figure 1, the length is 125 mm and the diameter is 5
The 1 mm pier server cap 1 has a cylindrical protrusion 6 for mounting by mounting a hollow cannonball-shaped core metal 7 on the tip, and the rear end face of the core metal is supported around the base of the cylindrical protrusion 6. A water-cooling jacket that has an annular bearing portion 2 with a width of 9 mm and a screw portion 5 with a length of 35 mm for screwing and connecting a mandrel bar at the rear part, and supplies cooling water from the inside of the screwed mandrel bar. 4 inside. A ring-shaped groove 3 having a width of 7 mm and a depth of 6 mm is provided in the ring-shaped core metal bearing portion 2, and a Ni layer having a thickness of 1 mm is built up as a base material in the groove, and then on the Ni layer. Build up 5mm thick Stellite STL-3G. The core metal 7 shown in cross section in FIG. 3 has a diameter of 51 mm and a material of 2Cr-1Ni.
Made of low alloy cast steel.

[0008]

As described above, in the pier server cap of the present invention, a hard alloy such as stellite is embedded in the abutment surface of the core metal to be supported and built up, so that the core metal can withstand severe impact friction. The bearing part of the peer server cap does not wear like the conventional one, and the period of use is greatly extended, and the steel pipe can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a side view of a peer server cap of the present invention.

FIG. 2 is a front view of the peer server cap of the present invention as viewed from the left side of FIG.

FIG. 3 is a side view of a core bar-mounted pier server cap showing only the core bar in cross section.

[Explanation of symbols] 1 Pier server cap 2 Core metal support 3 Hard alloy embedded overlay 4 Water cooling jacket 5 Screw 6 Columnar protrusion 7 Core

Claims (2)

[Claims] 1. A pier server cap having a cylindrical protrusion at the tip for covering and mounting a hollow cannonball-shaped cored bar, and a screw portion for screwing and coupling the tip of a mandrel bar at the rear end. A pier server cap for an Assel mill, wherein an embedded padding portion of a harder alloy than the bar cap is provided on the contact surface around the base of the protrusion of the core with the rear end surface of the core metal. 2. The pier server cap for an assel mill according to claim 1, wherein the alloy harder than the bar cap is a stellite alloy (Co-Cr-W).