JP2024084202A - Drill - Google Patents

Abstract

[Problem] The present invention aims to provide a drill that can make coolant reach the cutting edge at the tip of the drill even under normal hole drilling conditions using a general-purpose machine tool. [Solution] In a drill 10 having at least two or more cutting edges 1,1 extending outward from a central axis, flanks 2,2 formed continuous with the cutting edges 1,1, margins 5,5 formed continuous with the outer sides of the flanks 2,2, and main grooves 7,7 formed adjacent to the cutting edges 1,1, the drill 10 further has sub-grooves 8,8 formed parallel to the main grooves 7,7 on the rear side of the margins 5,5, and a communication portion 9 connecting one end of the main grooves 7,7 and one end of the sub-grooves 8,8. The communication portion 9 can also have a gradient that is inclined from the sub-groove 8 side toward the main groove 7 side. [Selected Figure] Figure 1

Description

The present invention relates to a drill that has a secondary groove on the outer periphery for flowing a coolant.

Conventionally, when drilling holes using a drill, in order to cool the workpiece, a coolant is applied from the machine tool to the drill and the workpiece, so-called an external oil supply method has been used for hole drilling. In addition, as disclosed in Patent Document 1, a groove through which the coolant can pass can be provided on the outer periphery of the drill, so that the coolant supplied externally from the machine tool can be efficiently sent to the tip of the drill.

In addition, instead of using an external oil supply system, it is possible to cool the workpiece during drilling by using a drill with oil holes, which pumps coolant from the machine tool from the end to the tip of the drill, as disclosed in Patent Document 2, and injects the coolant from near the cutting edge.

Japanese Utility Model Publication No. 61-028654 JP 2020-104253 A

However, the drill disclosed in Patent Document 1 requires a sufficient amount of coolant to reach the cutting edge from the shank side, compared to normal hole drilling conditions, and the drill rotation speed and feed speed also need to be reduced under the hole drilling conditions.

Furthermore, the drill disclosed in Patent Document 2 is limited to use with machine tools that have a mechanism for pumping coolant into the drill, i.e., machine tools equipped with a so-called internal oil supply mechanism, and in addition, drills with internal oil supply mechanisms (drills with oil holes) are more expensive than general-purpose drills.

The objective of the present invention is to provide a drill that can deliver coolant to the cutting edge at the tip of the drill even under normal hole drilling conditions using a general-purpose machine tool.

In order to solve the above-mentioned problems, the drill of the present invention has at least two or more cutting edges extending outward from the central axis, a clearance surface formed contiguous with these cutting edges, a margin formed contiguous with the outer side of the clearance surface, and a main groove formed adjacent to the cutting edges, and on the rear side of the margin, the same number of sub-grooves as the main grooves are formed parallel to the main grooves, and one end of the main groove is connected to one end of the sub-groove. The connecting portion connecting the main groove and the sub-groove can also be provided with a gradient inclined from the sub-groove side toward the main groove side.

The drill of the present invention has a communication section on the rear flank (second flank) that connects one end of the main groove to one end of the sub-groove, which has the effect of allowing the coolant to reach the cutting edge at the tip of the drill while maintaining normal hole-cutting conditions using a general-purpose machine tool.

FIG. 1 is a front view of the drill 10 of the present invention. FIG. 2 is a left side view of the drill 10 shown in FIG. 1 . FIG. 2 is a plan view of the drill 10 shown in FIG. 3 is a cross-sectional view of the communication portion 9 shown in FIG. 2 taken along line XX.

One embodiment of the drill of the present invention will be described with reference to the drawings. Fig. 1 shows a front view of a drill 10 according to one embodiment of the present invention, Fig. 2 shows a left side view, Fig. 3 shows a plan view of the drill 10 shown in Fig. 1, and Fig. 4 shows a cross section of line X-X (a cross section parallel to the axial direction of the drill 10) of the communication part 9 of the drill 10 shown in Fig. 2. As shown in Figs. 1 and 2, the drill 10 of the present invention has two cutting edges 1, 1 at the tip, and flanks (first flanks) 2, 2 and flanks (second flanks) 3, 3 on the rear side of each cutting edge 1, 1 in the rotational direction R.

The first flank 2, 2 and the second flank 3, 3 have different clearance angles, with the "first flank" also called the second surface and the "second flank" also called the third surface. In the circumferential direction of the drill 10, a first margin (front margin) 5, 5 is formed on the outer periphery of the cutting edge 1, 1, and a second margin (rear margin) 6, 6 is formed on the rear side in the rotation direction R, and the heels 4, 4 of the drill 10 are provided on the second margins (rear margins) 6, 6.

In the axial direction (longitudinal direction) of the drill 10, two main grooves 7, 7 formed in a spiral shape and two sub-grooves 8, 8 formed in a spiral shape parallel to the main grooves 7, 7 are provided from the tip side toward the shank 20 side. As shown in FIG. 2, the sub-grooves 8, 8 are formed on the rear side of the main grooves 7, 7 in the rotation direction R of the drill 10, and first margins (front margins) 5, 5 are provided on the rotation direction R side of the sub-grooves 8, 8, and second margins (rear margins) 6, 6 are provided on the opposite side of the rotation direction R (counter-rotation direction side).

The secondary grooves 8, 8 function as inflow passages for the coolant discharged from the machine tool, and the main grooves 7, 7 function as outflow passages for the coolant. In addition, at the tip side of the drill 10, i.e., the cutting edge 1, 1 side, one end of the main grooves 7, 7 and one end of the secondary grooves 8, 8 are spatially connected via communication parts 9, 9 during cutting (hole drilling). This is so that in the case of an external oil supply method, lubricant flows in from the secondary groove 8 side, entangles the chips cut by the cutting edge, and is properly discharged from the main groove side.

As shown in FIG. 4, which is a cross-sectional view of the communicating portion 9 parallel to the axial direction of the drill 10, it is desirable to provide an upward gradient in the communicating portion 9 from the sub-groove 8 side toward the main groove 7 side. It is also desirable that the cross-sectional area surrounded by the workpiece and the communicating portion during cutting is larger than the cross-sectional area surrounded by the sub-groove, the first and second margins (front margin, rear margin), and the workpiece.

1 Cutting edge 2 Flank (first flank)
3. Flank (second flank)
4 Heel 5 First margin (front margin)
6. Second margin (rear margin)
7 Main groove 8 Sub groove 9 Communication portion 10 Drill 20 Shank

Claims (2)

A drill having at least two or more cutting edges extending outward from a central axis, a clearance surface formed contiguous with the cutting edges, a margin formed contiguous with the outer side of the clearance surface, and a main groove formed adjacent to the cutting edges, further comprising a sub-groove formed in parallel with the main groove on the rear side of the margin, and a connecting portion connecting one end of the main groove and one end of the sub-groove. The drill according to claim 1, characterized in that the communication portion has a gradient that is inclined from the sub-groove side toward the main groove side.

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