JPS63267153A - Manufacture of drill - Google Patents

Abstract

PURPOSE:To prevent chattering oscillation and strengthen the rigidity of a drill by giving heat treatment and cylindrical polishing to a drill body and forming a relieving face on a land part leaving a part adjacent to a chip discharging groove as a margin by means of grinding. CONSTITUTION:A chip discharging groove 26 is formed by milling on a base metal body 24, on which heat treatment (hardening treatment and the brazing of a solid tip 23) is performed. Then, cylindrical polishing is carried out on a land part 32 and a retrieving face 34 is formed by grinding on the land part 32 which was subjected to the cylindrical polishing leaving a part adjacent to a chip discharging groove 26 as a margin 33. In this case, the retrieving depth of the retrieving face 34 is 0.1-0.3mm. Also, the surface roughness of a rising face from the retrieving face 34 to the margin 33 is 1.2S or less. In a drill 21 thus formed, a rising face close to a plane 28 is formed perpendicular to the margin 33 and a rising face close to a plane 29 is formed to be a negative rake angle.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method for manufacturing a drill in which a cylindrical tool body is provided with two chip discharge grooves extending rearward from the tip thereof.

"Prior Art" Conventionally, as the above-mentioned drill, a drill 11 as shown in FIGS. 12 and 13 is known. In this drill 11, a solid tip 13 made of cemented carbide is brazed to the tip of a base metal I2 made of steel. On the outer periphery of the base metal 12 and the exposed depth I3, two chip discharge grooves 14, 14 are formed at equal intervals in the circumferential direction from the tip toward the rear. This chip discharge groove 14 is defined by a first plane 15 facing in the direction of rotation and a second plane 16 facing in a direction opposite to the direction of rotation. And the first
A cutting edge 17 is provided at the tip of the flat surface 15 .

By the way, in the drill 11 as described above, if the cross-sectional area of the chip discharge 1-414 is increased in an attempt to improve the chip discharge performance, the thickness of the shaft center portion becomes thinner and the rigidity decreases. Furthermore, if the thickness of the shaft center portion is increased in an attempt to improve the rigidity, the cross-sectional area of the chip evacuation iM 14 decreases, resulting in a decrease in chip evacuation performance. For this reason, there has been a drawback that high-feed machining, which requires both high chip evacuation and high drill rigidity, cannot be performed.

Therefore, it is possible to improve both chip evacuation performance and drill rigidity, and the drill 2 is suitable for deep hole drilling and high-feed drilling.
1 was invented.

This drill 21, as shown in FIGS. 1 to 3,
A solid tip 23 made of cemented carbide is brazed to the tip of a base metal 22 made of steel.

The base metal 22 and the peeled tip 23 are composed of a base metal body (tool body) 24 and a peeled tip body (tool body) having a substantially circular cross section.
(tool body) 25. On the outer periphery of the base metal body 24 and the peeled tip body 25, there are two chip discharges 7rIt'26. The wall surface 27 defining the chip discharge groove 26 has a first plane 28 facing the rotation direction, a second plane 29 facing the opposite direction to the rotation direction, and the first plane 28. Said second
A third plane (third surface) formed between the plane 29 of
It is equipped with 30. The third plane 30 is
It is provided between the inner circumferential side edge of the plane 28 and the inner circumferential side edge of the second plane 29, and is disposed facing outward in the radial direction. Further, the third plane 30 and the first plane 2
At the intersection with 8 and the intersection between the third plane 30 and the second plane 29, a radius 31° 31 is formed to smoothly connect both planes, thereby preventing concentration of stress. It looks like this.

On the other hand, margins 33, . 33 is provided, and between these margins 33, 33, a second chamfer surface 34 is formed which is recessed toward the inner circumferential side.

Further, the outer peripheral portion of the margin 33 and the second plane 29
A chamfer 35 is formed at the intersection of the two to prevent stress concentration and the occurrence of cracks.

A cutting edge 36 is provided at the tip of the first plane 28 of the peeling depth main body 25. Further, an oil supply hole 37 having a circular cross section is formed in the axial center of the base metal body 24, and oil holes 38, 38 communicating with the oil supply hole 37 are formed in the tip surface of the peeled tip body 25. or is formed.

A cutting curve is supplied to the cutting blade 36 from the oil hole 38 through the oil supply hole 37.

Such a drill 21 is manufactured according to the following procedures (1) to (3).

(+) A second recess 34 is formed by milling on the base metal body 24 in which the chip discharge groove 26 is formed.

(2) Perform heat treatment (hardening treatment and brazing of the peeled depth 23); (3) Polish the portion of the land portion that will become the margin other than the second chamfer surface by cylindrical polishing.

"Problems to be Solved by the Invention" By the way, in the method for manufacturing the drill 21 described above, since the second chamfer is formed by milling before heat treatment, the second chamfer is bent due to the heat treatment process. may become eccentric. Therefore, there was a problem in that chatter vibration was likely to occur. Furthermore, if the second chamfer surface is eccentric, there will be variations in the second chamfer depth during cylindrical polishing, and the second chamfer depth may become zero depending on the location. Therefore, in order to avoid this, in the manufacturing method of this drill 21, the second cut depth is set to 0.5 m.
It is set as deep as m. For this reason, there was a problem in that the outer circumference of the drill, which is the most important part for supporting torsional stress and bending stress, was insufficient, resulting in a decrease in drill rigidity. Furthermore, since the depth of the recess is deep, the distance between the recess and the inner circumferential surface of the drilled hole increases. For this reason, there was a problem in that the cutting oil could not be sucked up along the second chamfer surface due to capillarity, and therefore the cutting oil could not be sufficiently distributed around the outer circumference of the drill. Due to the above-mentioned problems, the brazing part and the alloy part may be damaged.

"Means for Solving the Problem" This invention was made to solve the above problem, and includes a cylindrical tool body and two tools provided rearward from the tip of the tool body. a chip discharge groove, the wall surface defining the chip discharge groove having a first plane facing the direction of rotation, a second plane facing the direction opposite to the direction of rotation, and the first plane. a third surface provided between the second plane and the third plane, the third plane being an inner circumferential edge of the first plane and an inner circumferential edge of the second plane. and the curvature of the third surface is equal to or equal to the curvature of a curved surface having an arcuate cross section tangent to the first plane and the second plane at their respective inner circumferential edges. A drill body provided so as to be smaller than this is first heat treated, then cylindrical polishing is performed, and then ground to leave a margin adjacent to the chip evacuation groove in the land portion of the drill body. A second chamfered surface is formed.

"Function" The present invention comprises a cylindrical tool body and two chip discharge grooves provided rearward from the tip of the tool body, and the wall surface defining the chip discharge grooves rotates. comprising a first plane facing in the direction, a second plane facing in the opposite direction to the rotation direction, and a third plane raised between the first plane and the second plane, The third surface is provided between the inner circumferential edge of the first plane and the inner circumferential edge of the second plane, and the curvature of the third surface is equal to that of the first plane. The drill body, which is provided so that the curvature is equal to or less than the curvature of the curved surface having an arcuate cross section that touches the plane of the plane and the second plane at their respective inner peripheral edges, is first heat-treated, and then cylindrical polishing is performed. Then, by grinding, a second chamfer is formed leaving a margin adjacent to the chip evacuation groove of the land portion of the drill body, so that the second chamfer is eccentric to the axis. Therefore, chatter vibration can be prevented.

Furthermore, since the eccentricity of the second chamfer surface can be prevented, the depth of the second chamfer can be made shallower. Therefore, drill rigidity can be strengthened. Furthermore, the distance between the counterbore surface and the inner circumferential surface of the drilled hole can be narrowed, so that cutting oil can be sucked up along the counterbore surface by capillary action, and the cutting oil can be sufficiently distributed to the outer circumference of the drill. Be able to spread the word. For this reason, brazing can prevent damage to parts and alloy parts, and high-feed machining, busho-less machining, deep hole machining, and high-precision hole drilling can be performed.

"Example" An embodiment of the present invention will be described below.

The method for manufacturing a drill according to the present invention is shown in FIGS. 1 to 3.
The drill 21 shown in the figure is manufactured according to the following steps (1) to (3).

(1) Heat treatment (hardening treatment and brazing of the peeled chip 23) is performed on the base metal body 24 on which the chip discharge if 26 is formed by milling.

(2) Cylindrical polishing of the land part.

(3) A second chamfer is formed on the cylindrical polished land by grinding, leaving a margin adjacent to the chip discharge groove.

At this time, the recess depth of the recess surface 34 is set to 0.1 to
Form it so that it has a thickness of 0.3 mm. This is because when the recess depth is less than 0.1 mm, there is insufficient clearance for the margin 33, and when chips etc. adhere to the recess surface 34, the frictional resistance with the inner peripheral surface of the drilled hole increases. This is because In addition, if the recess depth is 0.3 mm or more, the outer circumference of the drill, which is most important for supporting torsional stress and bending stress, becomes insufficient, resulting in a decrease in drill rigidity.

Further, as shown in FIG. 4, the surface roughness of the second chamfer 34 and the rising surface 39 from the double chamfer surface 34 to the margin 33 is formed to be 1.2-S or less.

This is because when the surface roughness becomes 1.2-8 or more, as shown in Fig. 5, uneven edges appear at the intersection edge between the margin 33 and the rising surface 39, and the workpiece material This is because the burnishing torque increases due to welding.

In the drill 21 formed in this manner, it is desirable that the rising edge 39a near the first plane 28 be formed perpendicular to the margin 33, as shown in FIG. This is because if the rising surface 39a is inclined, when the margin is worn, the width of the margin will increase, and therefore the frictional force will increase and the burnishing torque will increase. Further, it is desirable that the rising surface 39b close to the second plane 29 be formed to have a negative rake angle with respect to the rotation direction. This is a stand up 3
This is because when 9b becomes a positive rake angle, the ridge line between the rising surface 39b and the margin 33 becomes a cutting edge, and therefore bites into the inner peripheral surface of the drilled hole, increasing the load torque.

In this way, in the manufacturing method of this drill, first,
Chips are discharged by milling on the base metal body 24 i1K 2
6 is formed, heat treatment (hardening treatment and brazing of the peeled chip 23) is performed, and then the land portion is cylindrically polished, and then a margin is formed on the cylindrically polished land portion adjacent to the chip evacuation groove. Since the second chamfered surface is formed by grinding, leaving the portion where the second chamfered surface 34 is formed, it is possible to prevent the second chamfered surface 34 from being eccentric with respect to the axis, and therefore chatter vibration can be prevented. Furthermore, since the eccentricity of the counter-boring surface 34 can be prevented, the depth of the counter-boring can be made shallow. Therefore, drill rigidity can be strengthened. Furthermore, the distance between the counterbore surface 34 and the inner circumferential surface of the drilled hole can be narrowed, so that the cutting oil can be sucked up along the counterbore surface by capillary action, and the cutting oil can be transferred to the outer circumference of the drill. It can be spread sufficiently. For this reason, brazing can prevent the parts and alloy parts from breaking. In addition, the chip discharge N26
A wall surface 27 defining a wall surface 27 is provided between a surface 28 facing the rotation direction, a second plane 29 facing the direction opposite to the rotation direction, and the first plane 28 and the second plane 29. Since the third flat surface 30 faces outward in the radial direction, it is possible to increase the cross-sectional area of the chip evacuation groove 26 and improve chip evacuation performance, while increasing the section modulus of the drill and improving its rigidity. Therefore, both the chip evacuation performance and the rigidity of the drill can be improved. Due to the above effects, high-feed machining, buttless machining, deep hole machining, and high-precision hole drilling can be performed.

Incidentally, the power change during biting was measured under the following cutting conditions for a conventional drill whose shank was not polished and a drill whose second chamfer and chip discharge groove of the negative yank body of the present invention were polished.

Rotation speed N - = 2400 rpffl feed U = 600
mm/min Workpiece material: FC25 (machining length 110 mm) Drill size: φI 4.7 mm x 300 n+m Lubricating method: Internal supply well (water-soluble 5 times diluted) Drilling method: Machine tool used for butsuless machining: Horizontal machining center (Komatsu GD machining center) ) As a result, the power fluctuation of the conventional drill is shown in Figure 7, and the power fluctuation of the drill of the present invention is shown in Figure 8, indicating that the power fluctuation of the drill of the present invention is smaller during biting. Recognize.

In the above embodiment, the third plane 30 is used as the third plane, but the third plane 30 is not limited to this, and as shown in FIGS. 9 and 10, is provided between the inner circumference side edge of the plane 28 and the inner circumference side edge of the second plane 29, and the first plane 28 and the second plane
It may also be a curved surface 41 having an arcuate cross section that contacts the plane 29 at the inner peripheral side edge of each of the curved surfaces 41 . As shown in FIG. 11, the inner peripheral edge of the first plane 28 and the second plane 2
The curved surface 42 or 43 may be provided between the inner circumferential edge of the curved surface 9 and the curved surface 42 or 43 having a smaller curvature than the curved surface 41 having an arcuate cross section.

"Effects of the Invention" As explained above, according to the present invention, the tool body includes a cylindrical tool body and two chip discharge grooves provided rearward from the tip of the tool body, A wall surface defining a chip discharge groove is provided between a first plane facing the rotation direction, a second plane facing the direction opposite to the rotation direction, and the first plane and the second plane. the third surface is provided between the inner peripheral edge of the first plane and the inner peripheral edge of the second plane, and the third surface is provided between the inner peripheral edge of the first plane and the inner peripheral edge of the second plane; A drill body provided so that the curvature of the surface No. 3 is equal to or less than the curvature of a curved surface having an arcuate cross section that contacts the first plane and the second plane at their respective inner circumferential edges. is first heat treated, then cylindrical polishing, and then ground to form a second chamfer surface, leaving a margin adjacent to the chip discharge groove of the land portion of the drill body, Chatter vibration can be prevented, drill rigidity can be strengthened, and cutting oil suction power due to capillary action can be improved. Therefore, high feed machining, buttless machining, deep hole machining
High-precision drilling provides the advantage of being able to perform machining.

[Brief explanation of drawings]

1 to 3 are diagrams showing one embodiment of the present invention, in which FIG. 1 is a side view thereof, and FIG. 2 is an arrow mark - ■ in FIG. 1.
Fig. 3 is a sectional view taken along the line, Fig. 3 is a distal end view in the axial direction;
The figure is a perspective view showing the margin and rising surface of the present invention, Fig. 5 is a perspective view showing the conventional margin and rising face, Fig. 6 is an enlarged view of the arrow ■ in Fig. 2, and Fig. 7 is the conventional FIG. 8 is a diagram showing power fluctuations when the drill bits of the present invention, and FIG. 9 and 1θ are diagrams showing other embodiments of the present invention. 9 is a sectional view at the same position as in FIG. 2, FIG. 10 is a view as seen from the tip in the axial direction, FIG. 11 is a view showing still another embodiment of the third drill, and FIG. 1 and 13 are diagrams showing an example of a conventional drill, in which FIG. 12 is a side view thereof, and FIG. 13 is a sectional view taken along the line xm-xm in FIG. 12. 21...Drill, 24...Base metal body (
Tool body), 25... Peeling chip body (tool body), 26... Chip discharge groove, 27...
Wall surface, 28...First plane, 29...
Second plane, 30...Third plane (third plane)
, 32... Land part, 33... Margin, 34... Second pick, 41, 42.43.
...Curved surface (third surface).

Claims (3)

[Claims] (1) It is equipped with a cylindrical tool body and two chip discharge grooves provided rearward from the tip of the tool body, and the wall surface defining the chip discharge groove faces the rotation direction. a second plane facing in a direction opposite to the rotation direction; and a third plane provided between the first plane and the second plane, the third plane is provided between the inner circumferential edge of the first plane and the inner circumferential edge of the second plane, and the curvature of the third plane is the same as that of the first plane and the inner circumferential edge of the second plane. The drill body, which is provided so that the curvature is equal to or less than the curvature of the curved surface having an arcuate cross section that touches the plane of No. 2 at its inner peripheral edge, is first heat treated, then cylindrical polishing is performed, and then grinding is performed. A method for manufacturing a drill, characterized in that a second chamfer surface is formed by leaving a margin adjacent to a chip discharge groove in a land portion of the drill body. (2) The recess depth of the recess surface is 0.1 to 0.3
2. The method of manufacturing a drill according to claim 1, wherein the drill is formed to have a diameter of mm. (3) The method for manufacturing a drill according to claim 1 or 2, wherein the second chamfer surface is formed so that the surface roughness is 1.2S or less.