JPH0711212U - Improved drill - Google Patents

Abstract

(57) [Summary] [Purpose] To enable smooth discharge of cutting chips. [Structure] A pair of substantially fan-shaped tip surfaces each having a cutting edge with a predetermined tip angle on one slanted side are formed on a conical surface having the chisel point of the tip of the round bar as its apex. In a drill having a spiral groove formed along a surface thereof, in at least one of the pair of cutting edges, a narrow chip-dividing groove extending from the cutting edges to the tip surface substantially along the cutting direction. An improved drill characterized by having a recess.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a twist drill used for drilling a metal material.

[0002]

[Prior art]

 Conventionally, as a drill of this type, a pair of almost fan-shaped tip surfaces each having a cutting edge with a tip angle of 59 ° on one slanted side are formed on a conical surface having the tip chisel point as the apex. A structure in which a spiral groove is formed along the outer peripheral surface of the main body is widely used.

[0003]

[Problems to be solved by the device]

 However, in the above conventional drill, the cutting powder cut by the cutting edge comes out in a considerably wide width corresponding to the entire width of the cutting edge, so that it becomes difficult to smoothly slide in the twist groove, and therefore the actual cutting When drilling holes in metal materials, chips often clog the holes, making it impossible to cut. Therefore, the conventional method was to repeat the work of discharging chips out of the hole by moving the drill up and down (so-called steps) after cutting to a slight depth. An object of the present invention is to smoothly discharge cutting chips without blocking steps.

[0004]

[Means for achieving the object]

 As a means for achieving the above object, the present invention forms a pair of substantially fan-shaped tip surfaces each having a cutting edge with a predetermined tip angle on one conical surface on a conical surface having the chisel point of the tip of a round bar as its apex. Then, in a drill formed by spirally forming a spiral groove along the outer peripheral surface of the round bar from the both cutting edges, at least one of the pair of cutting edges, the cutting edge being substantially along the cutting direction. We propose an improved drill characterized by having a narrow chip splitting groove that extends to the tip surface. An embodiment of the present invention will be described below with reference to the drawings.

[0005]

【Example】

 1 and 2, a drill (1) has a pair of substantially fan-shaped tip surfaces (3) and (3 ') facing each other on a conical surface having a chisel point (2) at the tip of a round bar as an apex. The cutting edges (4) and (4 ') are formed on each of the oblique sides of both tip surfaces (3) and (3'), respectively, and the cutting edges (4) and (4 ') form a circle. Twisted grooves (5) and (5 ') are spirally formed along the outer peripheral surface of the rod. The tip angles of the above cutting edges (4) and (4 ′) are, in this example, the tip angle (d) formed by the axial center line (S) passing through the chisel point (2) and one cutting edge (4) being 60. In addition, the tip angle (d ') formed by the axis (S) and the other cutting edge (4') is 59 °.

Among the above-mentioned cutting edges, in this example, a small chip splitting groove (6) extending from a substantially middle portion of the cutting edge (4) to the tip surface (3) along substantially the cutting direction is provided. It is recessed. (7) is the neck of the drill and (8) is the shank.

The operation of the above example is as follows. When the above-mentioned drill (1) is rotated in the direction of the arrow in Fig. 1 to start piercing and cutting the metal material with a constant pressing force, as shown in Fig. 3, the cutting edge (4) with the tip angle d = 60 ° is used. At the same time as cutting the swarf having a thick outer periphery, the swarf splitting groove (6) splits it into two narrow chips, and then the cutting edge (4 ') with the tip angle d' = 59 ° While cutting the uncut portion of the groove (6), a small chip with a thick center and a wide width is cut out, and this process is repeated to cut the hole, while each small chip cut into a twist groove. It moves smoothly in (5) and (5 ') and is discharged to the outside of the hole.

As another embodiment of the present invention, a plurality of chips (6) for splitting chips may be provided in the cutting edge (4). Further, both cutting edges (4) and (4 ') may be provided with grooves (6) respectively, and in that case, the cutting edge (4) and the cutting edge (4') are rotated. Install at different positions so that they do not overlap sometimes. As still another embodiment, there is an example in which one or both of the cutting edges (4) and (4 ') having the same tip angles (d) and (d') are provided with a groove according to the above-mentioned examples.

[0009]

[Effect of device]

 According to the improved drill of the present invention, the chips for splitting the chips can be cut into small pieces by the grooves for splitting the chips, which allows the chips to be smoothly moved out of the holes in the actual drilling work. It can be discharged, and a predetermined hole can be drilled by a one-stroke pressing drive without the step of the prior art.

[Brief description of drawings]

FIG. 1 is a partially omitted front view of an improved drill.

FIG. 2 is an enlarged bottom view of FIG.

FIG. 3 is an enlarged view of a lower end portion of FIG.

[Explanation of symbols]

 1 Drill 2 Chisel Point 3, 3'Tip Surface 4, 4 'Cutting Edge 5, 5' Twisted Groove 6 Chip Splitting Groove d, d'Tip Angle

Claims (1)

[Scope of utility model registration request] 1. A pair of substantially fan-shaped tip surfaces each having a cutting edge having a predetermined tip angle on one oblique side is formed on a conical surface having a chisel point at the tip of a round bar as an apex. A drill formed by spirally forming a spiral groove along the outer peripheral surface of a rod, in which at least one of the pair of cutting edges has a narrow chip split extending from the cutting edges to the tip surface substantially along the cutting direction. An improved drill characterized by having a groove for use.