JPS58151407A - Bit for spot facing for tap hole of blast furnace - Google Patents

Abstract

PURPOSE:To provide a titled bit for spot facing to which tips of hard metal are fixed easily and effectively by fixing the tips to a suitable number of the tip mounting holes provided around the air purging holes of steel bit bodies by press fitting or shrinkage fitting. CONSTITUTION:Tips 10 of hard metal are formed of a tough material contg. ca 10wt% Co selected from sintered tungsten carbide alloys. The tips 10 are formed into a spherical, circular conical or other shapes, and are fixed to the mounting holes of steel bit bodies 11, 12 having diameters slightly smaller than the diameter of the tips by press fitting or shrinkage fitting. The bodies 11, 12 are constituted in two steps as shown in the figure, and the mounting holes for the tips 10 are adequately disposed around air purging holes 13. Since the above- described tungsten carbide alloys have the characteristics that the alloys are weak to tensile force but are strong to compressive stress, these alloys add compressive load upon the tips 10 when fixed to the mounting holes of the bodies 11, 12 by press fitting or shrinkage fitting; the tips have hardness at much higher temps. as compared to the conventional tips fitted by brazing, therefore, a brittle hard metal is usable as tips.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a blast furnace tapping pit.

Generally, the vicinity of the taphole of a blast furnace consists of a blast furnace shell 1, a taphole reinforcing metal fitting 2, a blast furnace lens f3, a taphole 4, a taphole outlet refractory 5, etc., as shown in FIG. Here, tapping of the blast furnace is carried out by drilling a hole using a taphole rock presser, but when a predetermined amount of pig iron has been tapped, the taphole 4 drilled by the rock presser is re-opened using a mud gun (not shown). ).

However, if the taphole outlet refractory 5 deteriorates over time due to the erosion of hot metal or slag, the gas inside the blast furnace may leak to the outside, or mud leaks when the taphole is closed, making it impossible to close the blast furnace. There is. Therefore, it is necessary to repair the tap hole 4 at appropriate intervals.

Therefore, in order to repair the taphole, for example, the taphole 4 should be repaired at a depth of 200 to 500 mm with a diameter of 250 to 500 mm.
It is necessary to remove the outlet refractory ss and rebuild a new furnace wall in this part, and a tap hole will be drilled to remove the damaged furnace material 1 from the tap hole. A method is adopted in which a rock crusher is used to drill a hole with a pit having the diameter of the removed portion, or a manual breaker is used to crush the rock.

112 to 3 are a front view and a sectional view showing a conventional pit, in which a joint 6 is provided with a blade base 8 equipped with an air arm hole 7, and a blade base 8 is equipped with a stellite humidifier. A nine-blade body 9 with a sintered blade, or a pit with a cutting edge made by brazing ultra-hard metal such as sintered carbide were used.

However, the temperature gradient of the furnace wall near the taphole of a blast furnace is maintained at approximately 500°C just below the surface, as shown in the representative example in Series 4-, so the bit edge wears out quickly, which reduces the drilling speed. They were forced to work for long periods of time in high-temperature environments, making them slow. Therefore, high-temperature fi! degree ^
Therefore, the high-temperature hardness of each horizontal material is f151mK, which is superior to sintered tungsten carbide alloy (WC-Cod stellite). If the content is not set appropriately, if this sintered tungsten carbide alloy is brazed to the base of the blade, the difference in thermal expansion coefficient will result in a brazing cup of 1 m, which is 19 mm larger than the sintered tungsten carbide alloy. The bonded tungsten carbide alloy may crack and become unusable.

This invention was made in view of the above-mentioned nine circumstances, and adopts a high-hardness and excellent cutting edge material for the taper counter boring bit, and has a cutting edge design with good hole extraction efficiency, which results in early wear of the cutting edge. The purpose of this invention is to provide a blast furnace taper drilling bit aimed at solving the problem and improving the hole extraction speed.

Hereinafter, an embodiment according to the present invention will be described in detail based on FIG. 6. In the figure, reference numeral 10 denotes a cutting edge made of a hard metal, and a tough material with a CO content of about IQwt- is selected from among sintered tungsten carbide alloys. A steel bit formed into a conical or conical shape and slightly smaller in diameter than the blade body 10 is fixed into the mounting hole of the die 11.12 by press-fitting or burning. 12 has a 2RK configuration as shown in the figure, and the mounting hole of the hard metal blade body 10 is appropriately arranged around the air/measuring hole 13. Here, the sintered tungsten carbide alloy is It is weak against force but strong against compressive stress, so
A compressive load is applied to the hard metal blade body 10 by fixing it in the mounting hole of P&D by press-fitting or burning, etc. 9, which has better high-temperature hardness than conventional brazing fixation. In other words, a brittle hard metal can be used as a cutting edge.

In addition, according to the fixing method of the blade body 1G, the number of cutting edges can be increased by several times to ten times. This is the air/arm hole of the steel bit df! A suitable number of blade mounting holes are provided, and a hard metal blade is fixed into these mounting holes by press-fitting or burning, so that the blade can be fixed very elegantly and effectively. , and the number of blades is several times to 10 at once.
It is possible to increase the number of holes several times, and it has the effect of improving the wear resistance of the cutting edge and creating a cutting edge shape with good drilling efficiency.

In addition, the synergistic effect of improved wear resistance of the blade body and improved drilling efficiency is expected to dramatically improve drilling efficiency.
At the same time, significant effects such as lengthening of the life of the bit were obtained.

The hard blade material is not limited to sintered tungsten carbide alloy; similar effects can be obtained by using other hard metals. Other shapes such as a cylindrical shape or a conical shape may also be adopted.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the main parts of a blast furnace taphole, Fig. 2 is a front view showing a conventional bit, Fig. 113 is a longitudinal sectional view of Fig. 2,
FIG. 4 is an explanatory diagram showing the temperature gradient near the taphole in a blast furnace, FIG. 5 is a comparison diagram of high temperature hardness of each blade body material, and FIG. 6 is a perspective view of a bit according to the present invention. 10--Hard metal blade body, 11--D, 12-Gori, 13--Air arm arm hole. Patent applicant Kawasaki Jotetsu Co., Ltd. Patent applicant Mitsubishi Metals Co., Ltd. Agent Patent attorney Hide Sato Shoki Figure 4

Claims (1)

[Claims] A hard metal such as sintered tungsten carbide alloy is formed into a hemispherical, cylindrical, or conical shape to form nine blades, and the hard metal blade is shaped with a pin slightly smaller than the diameter of the blade and made of Shikam dI4. ) and properly placed mounting holes on the
A blast furnace tap hole boring pit characterized by being fixed by press-fitting or shrink-fitting.