JPH0733515U - Twist drill - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a cemented carbide drill having a nick along a twist groove of a twist drill up to a length substantially equal to the groove length. [Composition] A drill is formed by using a hole of a cemented carbide material having a spiral hole and grinding so that this hole appears as a nick. The nick thus obtained has a length almost equal to the groove length and a constant shape.
Therefore, even if re-grinding is repeated from the tip of the drill, no additional nick work is required, and a drill with stable chip control performance can be obtained.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a twist drill with a nick made of cemented carbide, and eliminates the need for additional machining of the nick when regrinding the drill.

[0002]

[Prior art]

 In drills and end mills, it is a generally practiced technique to form notch steps or notch-shaped grooves on the cutting edge, which are so-called nicks, for the purpose of dividing chips during cutting. .

FIG. 4 shows a typical example of a conventional nicking method for a twist drill. The groove of the nick 4 is provided on the rake face side of the front cutting edge 6 so as to follow the spiral groove 5 of the drill 1. A twist drill with a sufficiently long groove for this nick 4 has already been devised, but the machining of a long nick by grinding requires advanced technology and has not been put to practical use.

FIG. 5 shows another typical conventional example of the nick 4, in which the groove of the nick 4 is provided on the flank side of the front cutting edge 6.

[0005]

[Problems to be solved by the device]

 In solid drills, when it is judged that the cutting edge has reached the end of life, it is usually re-ground and reused so that it is driven in from the tip side of the drill. And many repeat this many times.

As described above, it is generally necessary to use a drill as shown in FIG. 4 because it requires a high technique to grind a nick that maintains a sufficient length along the twist groove from the beginning. It is used, but this drill requires additional nicks as it regrinds. The example in Fig. 5 is also in practical use, but since the nick disappears each time the drill is re-ground, additional machining of the nick is required each time.

[0007]

[Means for Solving the Problems]

 In order to solve the above problems, the twist drill of the present invention is provided with nicks along the spiral groove continuously from the cutting edge to the vicinity of the groove length. In order to achieve such a shape, the material made of cemented carbide uses a material with a spiral hole that penetrates inside, and this spiral hole forms the nick. By processing the twist groove, which is a chip discharge groove, as described above, the shape can be obtained.

[0008]

[Action]

 As described above, since the spiral hole provided in the material forms the nick, a long nick along the twist groove can be obtained. The turning radii of the nicks are, of course, offset from each other, which allows chips to be ejected in the radial direction during cutting.

The drill is gradually shortened from the tip side with re-grinding, but the twist drill of the present invention has a sufficiently long nick, so that it is not necessary to additionally process the nick every time re-grinding. Moreover, since the nick shape is always constant, stable chip control performance can be obtained.

[0010]

【Example】

 Next, an embodiment of the twist drill of the present invention will be described with reference to the drawings.

FIG. 1 is a front view of a twist drill 1 according to the embodiment. 2 (b) is a tip portion of the twist drill 1, and FIG. 2 (a) is a side view thereof.

FIG. 3 shows a material 2 made of cemented carbide as a material of the twist drill 1, and two holes 3 are spirally penetrated inside the material 2 having a round bar shape. The two holes 3 are formed so that their turning radii are displaced from each other. Further, depending on the size of the drill 1, the number of holes 3 may be three or more. Such a perforated material 2 can be obtained by, for example, the method disclosed in JP-A-62-240701. The material 2 is subjected to a grinding process to be finished into a product as shown in FIG. At that time, the twist groove 5 is formed so that the hole 3 appears as a nick 4. That is, about half of the cross-sectional shape of the hole 3 is shaved off and the hole 3 is processed so as to remain as a groove having a half-moon cross section. Thereby, the nick 4 is obtained as a groove having a constant cross-sectional shape that is continuous from the cutting edge of the front cutting edge 6 to the vicinity of the groove length L.

The holes 3 are left as they are, except for the twist groove 5 of the twist drill 1, and can be used as holes for internal oil supply. Although this does not reach the effect of refueling the oil hole penetrating to the vicinity of the front cutting edge 6, the effect of refueling is higher than that of the method using external refueling.

[0014]

[Effect of device]

 The present invention is to realize a twist drill made of cemented carbide with a sufficiently long nick along a spiral groove. With such a drill, a nick with a constant shape always appears even if regrinding is repeated such that the drill is driven in from the tip side, so stable chip control performance can be obtained, and the drill It can be used effectively.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of the twist drill of the present invention.

2A is a side view of the tip of the drill shown in FIG.
(B) is the front view.

FIG. 3 is a material diagram of the drill shown in FIG.

FIG. 4 is an example of a conventional twist drill, (a) is a side view of a tip portion, and (b) is a front view thereof.

FIG. 5 is another example of a conventional twist drill with a nick,
(A) is a side view of a front-end | tip part, (b) is the front view.

[Explanation of symbols]

 1 Twist drill 2 Material 3 Hole 4 Nick 5 Torsion groove 6 Front cutting edge

Claims (1)

[Scope of utility model registration request] 1. A nick 4 is formed on a pair of front cutting edges 6 provided at the tip of a drill body made of cemented carbide, and a groove of this nick 4 is formed along the axis of the drill. While following the twist groove 5 provided on the outer periphery,
In the twist drill 1 that is formed continuously from the cutting edge of the front cutting edge 6 to the vicinity of the groove length L, the twist drill 1 is made of a material 2 having a spiral hole 3 therein, The twist drill characterized in that the groove 4 is formed by utilizing the hole 3.