RU2581541C2 - Drill for single-side cutting with hard-alloy body - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: drill contains body out of hard alloy, connected by means of trunnion with steel shank. In body external V-shape straight channel and internal straight channel with permanent profile are made, the later has curvilinear form of kidney shape with different diameters of arc. The shank is made as single part with trunnion.

EFFECT: improved shaving removal from machined hole, drill centring, increased accuracy of made holes with small diameters.

1 tbl, 4 dwg

Description

The invention relates to mechanical engineering and can be used for drilling deep holes of small diameters.

Various tools for drilling deep holes are known from the prior art, such as single-sided (drill) drills, BTA drills, ejector drills, etc. Single-cut drills are most suitable for drilling deep holes of small diameters.

Known single-sided blade drill for drilling holes of small diameter (Pat. No. 2176176, IPC VV 35/00). The cutting part of the drill contains one feather with a cutting edge having a reverse sharpening, and an auxiliary edge. The disadvantage is the inability to drill holes without making a lead-in.

A single-edged gun drill is known, the cutting head of which has two holes for supplying cooling during drilling, and at least one of them has a curved or round shape (Application No. JP 2013-139059 A, 2013.7.18, IPC V23B 51/06). The presence of two holes in the cutting head greatly complicates the technology of its manufacture.

It is known gun drill for drilling deep holes, which contains a cutting head having an outlet for refrigerant, in communication with the channel for supplying refrigerant to the distal end surface at the far end of the hollow tail section having a groove for removing chips, the cross-section of which in the longitudinal direction has V- shaped on the outer surface and has an inner space made in the form of a channel for supplying refrigerant. The cutting part of the cutting head is made of cermet carbide. Part of the cutting head, which is in sliding contact with the inner periphery, with the exception of its cutting part, consists of a material having a hardness that is higher than the hardness of the cermet hard alloy (Pat. No. 2409452, IPC V23B 51/00). The presence of a steel rod reduces the strength and rigidity of the drill.

The objective of the invention is to improve the accuracy of the resulting holes of small diameters by increasing the strength and rigidity of the drill.

The single-sided drill has a carbide stem and shank. The stalk is made with a single cutting unit. Along the entire length of the stem, an external V-shaped direct channel and an internal direct channel of a constant profile are made, having a curved shape of a kidney-shaped type with a diameter D _{1 of} one arc larger than the diameter D _{2 of} another arc. The shank is made integral with the pin in which the carbide stem is located.

The invention is illustrated by drawings, where

in FIG. 1 shows a single-sided drill with a carbide stem;

in FIG. 2 shows the cutting part of a single-sided drill with a carbide stem (type A);

in FIG. 3 - cross section of the stem of a drill of unilateral cutting with carbide stem (section BB).

in FIG. 4 is a cross section of the connection of the trunnion and the stem of the drill single-sided cutting with carbide stem (section bb).

A single-sided drill with a carbide stem consists of a carbide stem 1 connected to a steel shank 2 through a trunnion 3. The stem 1 and shank 2 are inseparable from the solder joint 4. Stem 1 is a carbide rod with an external V-shaped straight channel 5, at the end of which a cutting part is made, which has cutting edges 6 and 7 and a supporting surface 8. Also, a direct internal channel 9 is made in the stem 1, which is connected on one side to the channel 10 in the shank 2, and from the cutting side ti forms an outlet 11 for cooling the treatment zone. On the shank 1 is made flat 12, which serves to fix the drill on the machine.

The drill works as follows. When setting the rotation R counterclockwise, the drill is informed of the axial feed. The cooling medium is supplied through the channel in the shank 2 and the direct internal channel 9 in the stem 1 and through the hole 11 enters the processing zone. The curvilinear shape of the kidney-shaped channel with a diameter D _{1 of} one arc, larger than the diameter D _{2 of} another arc, for supplying cooling increases the flow rate of the cooling medium and increases the cooling of the cutting edges 6 and 7, increasing their service life. The cutting edges 6 and 7 carry out drilling of the hole and the formation of chips, which is removed together with the cooling via an external V-shaped direct channel 5 into a special container. The radial forces arising due to the axial displacement of the cutting edges during the drilling process are perceived by the lateral surface 8 and press the drill to the surface of the hole obtained. This ensures centering of the drill, reduces the withdrawal of the axis of the hole and the fluctuation of the diameter of the hole, and also smoothes the microroughness of the hole surface. When the drilling process is completed, the rotation of the drill is stopped and it is removed from the hole obtained in the direction opposite to the axial feed direction.

A single-sided drill with a carbide stem A1 and a drill according to patent No. 2409452 are used. An oil fluid is used as a cooling medium, which is fed into the treatment zone under a pressure of 11 MPa and holes are drilled with a diameter of 2.05 mm and a length of 40 mm in steel billets with a chromium content of about 1% (hardness HB = 189 ... 207). Estimate the total resistance L _∑ when drilling by the number of drilled holes before the drill breaks, the maximum variation in the diameter of the hole Δ, the average diameter of the hole D _cp and the average deviation from roundness Δ _cr . The results are shown in table.

Suggested drill A1

The tail part is made of steel, has a length of 68 mm, an outer diameter of 10 mm and a channel for supplying coolant 1.8 mm. The stem with the cutting part has a length of 155 mm and is made of hard alloy type VK6-OM according to GOST 3882-74, while the cutting part has a length of 14 mm and the area of the outlet for supplying cooling 0.32 mm ² .

Drill according to patent No. 2409452

The tail part is made of steel, has a length of 68 mm, an outer diameter of 10 mm and a channel for supplying coolant 1.8 mm. The stem is made of structural steel and has a length of 141 mm. The cutting part soldered to the steel stem is made of hard alloy VK6-OM according to GOST 3882-74, has a length of 14 mm and the area of the outlet for supplying cooling 0.32 mm ² .

The technical result is to reduce fluctuations in the diameter of the hole and deviations from the roundness of the hole.

Claims (1)

Drill-sided cutting, comprising a shank and a carbide stem with a cutting part, characterized in that the carbide stem is formed over the entire length with an outer V-shaped forward channel and the inner straight channel of constant profile having a curved shape kidney-shaped form having a diameter D ₁ of one arc, a large D ₂ diameter of the other arc, the carbide stem is located in a pin formed integrally with the shank.

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