SU1632646A1 - Twist drill - Google Patents

Abstract

The invention relates to metal cutting and can be used in the processing of holes with twist drills in difficult-to-machine materials. The aim of the invention is to increase tool life. The spiral drill with a diameter D contains a back surface 1 with an angle ОЈ, a point point 2 of the front surface at the axis of the drill. The cut 3 of the nape of the feather is made along the helical surface, in which the straight line forming 4 is tangent to the radius R of the point of the point 2, the elevation angle GJt of the peripheral helix exceeds the inclination angle (0 of the chip groove on Yu ... 200, and the intersection line 5 of the main back surface 1 with a screw cut surface 3 of the occipital part located at a distance b, equal to 0.2 ... 0.3 of the diameter D of the drill from the peripheral points of the main cutting edges. 8 ill., Table 2 S

Description

Fig1

The invention relates to the field of metal cutting and can be used when drilling holes in difficult-to-work materials.

- The purpose of the invention is to increase tool life,

FIG. 1 shows the cutting part of a twist drill, side view; in fig - 2 - the same, front view; Fig. 3 is a plot of torque (MKr) versus depth of processing by drills with a base (known) geometry; in fig. 4 - a graph of the dependence of the axial force (Dew) on the depth of processing drills with basic geometry; FIG. 5 is a plot of torque (Mcr) versus depth of processing by drills with the proposed geometry; figure 6 is a graph of the axial force (Pot) on the depth of processing drills with the proposed geometry; in fig. 7- a graph of averaged values of torque (Mc) from the type of drill sharpening (with the basic and proposed geometry) during drilling, holes; in fig. 8 is a graph of averaged values of axial force (Dew) on the type of drill sharpening (with the base and proposed geometry when drilling holes.

A spiral drill with a diameter D contains a back surface 1 with an angle ΦЈ, a point point 2 of the front surface at the drill axis with a partial replacement (reduction of length) with a transverse cutting edge and a correction of the leading angle y on the main cutting edge.

The cut 3 of the nape of the feather is full along the helical surface, in which the straight line forming 4 is tangent to the radius R of the point of the point 2, the elevation angle of the COC of the peripheral helix exceeds the angle of inclination of the chip groove O at 10-20 ° C, and the line 5 of the intersection of the main back The surface 1 of the screw surface of the cut 3 of the occipital part is located at a distance b, equal to 0.2-0.3 of the diameter of the drill D from the peripheral points of the main cutting edges.

Example. For comparative tests, drills D 8 mm were selected from alloy R9M4KB with an angle of 33 ° in the amount of 10 pcs. Sharpening of drills is made by machine with the geometry: 14 ° - main rear angle, 2 ° 130 ° angle at the top, ft - 5 ° - rake angle, R te 2 mm - radius of undercut.

An undercut of the front surface was made with partial replacement of the transverse edge and correction of the front angle. Then the drills were divided into 2 batches of 5 pcs. The first batch was taken as the base part, and on the drills of the second batch, a cut of the occipital part was made according to the invention: SOS 48 °, b 2 mm

The resistance tests were carried out on samples in the form of cylinders with a diameter of 30 mm and a height of 70 mm from heat-resistant EI-787 VD alloy (ХН35ВТЮ-ВД), which were fixed in a 3-jaw chuck installed in the UDM-500 dynamometer.

The recording of the current values of the torque (II c «) and the axial force (P 00) during the drilling process was carried out periodically: during drilling; after drilling 5 mm, fix the II ““ and P0o in the path of the 2 mm drill; after drilling the next 5 mm with a record of M p and P wastes on a path of 2 mm, etc .; after drilling the next 5 mm with a record

M

KR

and P00 on a 2 mm path, etc.

Thus, further for

comparisons were taken values of M

cr

and Ros, fixed at a depth of machined holes of 2, 9, 16 and 23 mm.

Testing of drills was carried out on a radial drilling machine in the following modes: V 4.5 m / min, S 0.063 mm / rev. Coolant - aqueous solution of Emulsol № 73.

The experiments were repeated three times, as can be seen from Tables 2 and 1, where the values of MK and POC are given.

From the graphs in FIG. 3-6 it can be seen that with machine sharpening the drills show a fairly stable operation (the variation of power parameters in experiments at the same level is insignificant)

From the graph in FIG. 7 shows that

M

cr

significantly, up to 35% less with

machining offered drills compared with the basic sharpening. This is due to the improved evacuation of chips from the cutting zone.

The axial force is practically unchanged (Fig. 8), since the length of the transverse edge, the chip separation grooves and the main cutting edges are identical. Some reduction in dew can also be explained by improvement.

conditions of chip transportation in the near-tip zone,

The torque values at different depths of the hole being machined are given in Table. one.

The values of the axial force at different depths of the hole being machined are given in Table. 2

The tests carried out under production conditions showed that the use of carbide drills with a diameter of 7–13 mm with the proposed geometry increases durability by 2–3 times, and high-speed drills with a diameter of 8–26 mm - by 1.5–2 times.

Formula

acquisitions

Spiral drill containing the shank and the working part with a chip 10

6326466

grooves, sharpening on the back surface, cut off by the nape of the pen and undercutting the front surface at the drill axis, characterized in that, in order to increase durability when machining viscous difficult-to-work materials, the cut of the nuchal part of the pen is made along a helical surface, in which the straight line tangent to the undercut radius, and the angle of elevation of its peripheral helix exceeds the inclination angle of the chip groove 15 by 10-20 °, while the line of intersection of the main rear surface with the helical surface with eza occipital portion extends from a peripheral point of the cutting edge at a distance equal to 0.2-0.3 drill diameter.

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Claims (1)

'formula invented Spiral drill containing a shank and a working part with chips 1632646 ^{6 with} grooves, sharpening on the back surface, cut off the nape of the pen and grinding the front surface at the axis of the drill, characterized in that, in order to increase resistance when processing viscous difficult to process materials, a cut of the nape of the pen is made on a helical surface, in which a straight line generatrix it is tangent to the radius of the grind, and the angle of elevation of its peripheral helix exceeds the angle of inclination of the chip groove by 10-20 ^s , while the line of intersection of the main rear surface with the vin- ·. the cut surface of the neck of the occipital part is located from the peripheral point of the main cutting edge at a distance equal to 0.2-0.3 of the diameter of the drill.