RU2325443C2 - Blast furnace taphole drill bit - Google Patents

Abstract

FIELD: metallurgy, equipment for heat treatment.

SUBSTANCE: said utility invention relates to the field of metallurgy, specifically, to blast furnace taphole drill bits. The drill bit contains a rod with a breaking element at its end. The breaking element is designed as a cross-shaped or three-point chisel bit. The rod is designed with a through axial channel and side channels for coolant feeding to the drill bit. Slant slots are made between the teeth of the breaking element. The teeth are made with a cutting angle of 125-130°. The depth of the slant slots is 5-11 mm, and their width is 7-12 mm. The invention extends the breaking element service life and decreases the taphole drilling time.

EFFECT: increased service life of breaking element of blast furnace taphole drill bit.

2 cl, 3 dwg, 1 tbl

Description

The invention relates to a drilling tool, namely to bits for rotary hammer drilling, used mainly in the metallurgical industry for opening openings of blast furnaces.

Known crown for rotary hammer drilling, including a shank and a working head, divided in the end part into feathers reinforced with carbide inserts (SU 1430495 A, CL ЕВВ 10/36, 1988).

A disadvantage of the known crown is the high probability of its breakage during operation due to the loss of inserts from the crown body due to their unreliable fastening, as well as the need to regrind the tool during wear of the inserts.

Known crown for rotary hammer drilling, containing a shank made in monolithic and a working head, divided in the front part by a crosswise cut into solid working feathers with a shank, made with a half-toroidal active surface turning into a truncated cone, while the working head is made with a central flushing channel, connected with cuts, turning into pockets to remove little things (RU 2201490 C1, CL ЕВВ 10/36, 03/27/2003).

The known device is devoid of the disadvantages associated with the presence of carbide inserts, however, it does not have a high enough productivity and service life, due to the fact that the destruction of the rock is carried out by feathers due to impact.

A crown for shock-rotary drilling is known, the casing of which is made monolithic single-pin, and the working surface is made in the form of a body of revolution relative to the axis of symmetry of the crown and is peripherally divided into feathers in the form of a Maltese cross and has pockets for removing drilling products, while in the casing there are two side flushing holes connected to the central channel (RU 2202029 C2, class ЕВВ 10/36, 04/10/2003).

In this design, the shock load is perceived by the central massive part of the head - rock-breaking pin, allowing shock loads, in which the destruction of the rock due to rotation of the crown. Thus, the absence of shock loads on the feathers leads to an increase in their service life. However, this is achieved by reducing the overall performance of the crown. Moreover, the known device is not suitable for use in the metallurgical industry, in particular, for opening openings of blast furnaces.

The closest to the described crown in technical essence and the achieved result is a hammer for rotary hammer drilling, used in the metallurgical industry and containing a rod with a destructive element made in the form of a cross-shaped or three-feather chisel head mounted on the end of the rod, and the rod is made with a through axial channel and side channels for supplying a cooler to the head (RU 38760 U1, class СВВ 7/12, 2004).

The disadvantage of the closest analogue is the relatively low durability of its destructive element - the head due to increased wear of the cutting edge due to the accumulation of drill fines in the zone of rock destruction. This leads to additional tool consumption. In addition, due to suboptimal sharpening of the cutting edges, the duration of the opening operation of the tap hole is increased, which leads to an increase in the time for the release of cast iron from the furnace.

The objective of the invention is to develop a crown for shock-rotary drilling, free from the above disadvantages of the closest analogue, and therefore, the technical result provided by the invention is to increase the service life of the head as a destructive element, as well as reducing the opening time of the tap hole.

This result is achieved by the fact that in the crown for shock-rotary drilling, mainly for opening the notches of blast furnaces, containing a rod with a destructive element made in the form of a cross-shaped or three-feathered bit of a chiselled type mounted on the end of the rod, the rod being made with a through axial channel and side channels for supplying the cooler to the head, inclined grooves are made between the cutting teeth of the cutting element, and the teeth of the cutting element are made with a cutting angle of 125-130 °.

In addition, the depth of the grooves can be 5-11 mm, and the width is 7-12 mm.

The invention is illustrated by the accompanying drawings, in which Fig. 1 shows a general view of the crown, in Fig. 2 is a view A in Fig. 1, and in Fig. 3 is a section BB in Fig. 2.

The crown for opening the notches of the blast furnaces consists of a housing 1, on one end of which a shank 2 is made with a thread for connection with a perforator, and a cruciform or three-headed head 3 with three washing holes 4 and cutting elements with teeth 5 is planted at the other end made inclined grooves 6.

When the crown is used to open the notches of the blast furnaces, the destruction of the tap-hole mass by the central part of the crown due to impact occurs. The channel is cleaned of destroyed products by compressed air or cooled inert gas entering through the flushing holes 4. Removing drill trifles provide grooves 6.

The design of the working part of the crown helps to maintain the original shape during wear, since the active part of the crown, which destroys the rock, has a large area and slightly wears out, and the peripheral part has a margin for wear. Therefore, the crown has a self-sharpening effect. The increased height of the working teeth determines their margin for wear and, therefore, the increased working life of the tool. The presence of a rock-cutting pin in the crown as a whole allows for increased shock loads.

To determine the optimal size of the grooves, batches of crowns with different sizes of grooves were made, which were tested on a blast furnace No. 3 at TulaChermet OJSC. The results are shown in the table, from which it can be seen that the optimal groove dimensions for a crown with a diameter of 65 mm are: width - 10 mm, and depth - 7 mm. The dimensions of the groove, more than the above, lead to structural loosening of the tooth and premature failure. With a decrease in the size of the groove, a decrease in drilling efficiency (an increase in the opening time of the notch) or a failure of the crown-rod due to rolling of the cutting edge are observed.

It has also been experimentally established that the optimal angle of sharpening of the tooth of the crown is 125-130 °, which is especially important for all-steel crowns (without carbide). At sharpening angles of less than 125 °, the cutting edges of the teeth are rolled during impacts of the punch, which increases tool consumption and increases the cutting time of the notches, and at angles exceeding 130 °, the teeth of the cutting elements break and the crown performance decreases sharply due to the increased cutting time of the notches .

The invention is not limited to the purpose indicated in the formula, but may find application in other industries, for example, mining, when drilling rocks of low strength.

Table Groove size (mm) Sharpening angle, ° Opening time of the tap hole (min) or cause of crown failure Depth Width 3 5 110 Cutting edge rolling 5 5 110 Cutting edge rolling 7 5 120 Cutting edge rolling 9 5 132 18.10 eleven 5 130 7.40 3 7 120 Cutting edge rolling 5 7 120 Cutting edge rolling 7 7 127 5.00 9 7 130 6.50 eleven 7 125 5.20 3 10 120 Cutting edge rolling 5 10 126 4.20 7 10 127 3.25 9 10 130 1 tooth breakage eleven 10 133 1 tooth breakage 3 12 120 Cutting edge rolling 5 12 120 Cutting edge rolling 7 12 126 4.00 9 12 130 2 tooth breakage eleven 12 130 2 tooth breakage 3 fifteen 120 Cutting edge rolling 5 fifteen 120 Cutting edge rolling 7 fifteen 120 1 tooth breakage 9 fifteen 120 2 tooth breakage eleven fifteen 120 4 tooth breakage

Claims (2)

1. A crown for impact-rotary drilling, mainly for opening a notch of a blast furnace, comprising a rod with a destructive element made in the form of a cross-shaped or three-feather chisel head with cutting elements with teeth planted at the end of the rod, the rod being made with a through axial channel and side channels for supplying the cooler to the head, characterized in that the inclined grooves are made between the teeth of the cutting element, while the teeth are made with a cutting angle of 125-130 °. 2. The crown according to claim 1, characterized in that the depth of the grooves is 5-11 mm and a width of 7-12 mm.

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