JP2003019614A - Twist drill having oil hole - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a twist drill having an oil hole capable of ensuring the sufficient feed quantity of a cutting fluid. SOLUTION: In the oil hole 7 comprising a main pipe 8 and a branch pipe 9, the main pipe 8 is formed of two stop holes cut parallel to the axis of rotation from a rear end to a forward end of a drill body, and the branch pipe 9 is formed of a communication hole of the forward end of the drill body with the main pipe 8. The main pipe 8 is formed in a thick wall part away from a web part at the drill center, and set at the position so as not to pierce two twisted chip discharge grooves 4. Sufficient feed of the cutting fluid can be ensured by two main pipes 8, and both the main pipes 8 and the branch pipe 9 have a shape to be easily formed.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a twist drill having an oil hole, and more particularly to an oil hole provided in a throw-away type drill or a blade drill. 2. Description of the Related Art FIGS. 5 and 6 show an example of a conventional twist drill 1 with an oil hole, which illustrates a throw-away type drill. The oil hole 7 of the drill includes one main pipe 8 and two branch pipes 9. Main 8
Is a stepped blind hole that is formed concentrically with the rotation axis from the rear end to the front end of the drill body. The branch pipe 9 branches off from the front end of the main pipe 8 and opens at the front end of the drill body. I have. The cutting fluid supplied from the rear end of the drill body is spouted from this opening, and has an effect of promoting cooling of cutting heat and chip discharge. FIGS. 7 and 8 show another example of a conventional twist drill 1 with an oil hole, which also shows a throw-away type drill. I have. An oil hole 7 of this drill is formed by a thick main pipe 8 drilled in the shank 2, a connection hole 10 drilled from the side of the flange 3 and an embedding plug 11 for closing the mouth thereof, and a connection hole from the tip of the drill body. 10 and two branch pipes 9 provided in communication with each other. This branch pipe 9 is disposed by selecting a thick portion away from the web at the center of the drill section, and is obliquely corresponding to the twist of the chip discharge groove 4 so that the oil hole does not break out of the drill body. Direction. [0004] In drilling,
The twisting of the chip discharge groove is superior to the straight groove in that the chip discharge action is enhanced. Also, the cutting fluid increases the cutting speed and enables deep hole machining. FIG. 5 described in the prior art is an example of the configuration of an oil hole most commonly employed for an internal lubrication system in a throw-away drill or a bladed drill. However, the diameter of such an oil hole cannot be increased because the main pipe is provided in the web portion when the discharge amount of the cutting fluid is to be increased. It is not recommended to reduce the depth of the chip discharge groove in order to increase the hole diameter, since this will cause chip discharge failure. FIG. 7 described in the prior art is an example in which such a problem is solved. That is, since the main pipe is sufficiently thick and the branch pipe is also arranged so as to avoid the web, a constant hole diameter can be secured even if the chip discharge groove is deep. However, when manufacturing a drill, the branch pipe is machined with a diagonal hole that is considerably deeper than the diameter of the hole from the tip of the drill body. A high jig and high positioning accuracy are required. In addition, it is necessary to provide a connection hole for connecting the main pipe and the branch pipe, which requires extra labor and cost. In addition, such a shape has a problem that a long and straight hole must be formed while sewing the twist of the chip discharge groove, and it can be applied only to an extremely weak twist. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has two chip discharge grooves with a twist around a rotation axis, and a main body. In a twist drill having an oil hole formed therein with an oil hole formed along a rotation axis, the oil hole has two stops formed in parallel with the rotation axis from a rear end to a front end of the drill body. It is characterized by comprising a main pipe consisting of a hole, and a branch pipe communicating with each of the main pipes from the tip of the drill body. [0007] By providing two main pipes of oil holes in a thick portion avoiding the web portion, it is possible to ensure a sufficient discharge of cutting fluid. Since the main pipe is a straight hole parallel to the rotation axis, there is no difficulty in manufacturing. However, a hole position must be set so as not to penetrate the chip discharge groove, and sufficient study is required at the design stage. This is also facilitated by the design using CAD. According to the present invention, the most common (the ratio of the hole depth to the drill diameter) = 3 can handle a twist angle of about 20 °. Since the length of the branch pipe is short, it can be easily processed using a normal solid drill. Next, an embodiment of the present invention will be described with reference to the drawings. FIGS. 1 to 3 show a twist drill with an oil hole according to the present invention, which is a throw-away type drill having a relatively small twist angle.
The shank 2 and the flange 3 are provided on the rear end side of the drill, and two chip discharge grooves 4 are formed on the front end side of the drill body with twist around the rotation axis. The cutting edge tip 5 is screwed and fixed to the tip seat cut out at the tip end of the chip discharge groove 4 with a tightening screw 6 to form a drill blade. The two cutting edge tips 5 are displaced in the radial direction, and share the roles of the center edge tip and the outer edge tip. An oil hole 7 extends through the inside of the drill body. The oil hole 7 is constituted by a main pipe 8 and a branch pipe 9. Of these, the main pipe 8 is a blind hole which is provided at a position distant from the web portion and is formed from the rear end to the front end of the drill body in parallel with the rotation axis. At this time, as shown in FIG. 2 and FIG. 3, the positional relationship between the chip discharge groove 4 with twist and the main pipe 8 differs depending on the cross-section, so that the main pipe 8 does not break into the chip discharge groove 4. Choose a location and drill as deep a hole as possible. On the other hand, the branch pipe 9 is set at an opening position that is most effective for cutting, and is opened by connecting this opening to the tip of the main pipe 8. The use of two main pipes 8 ensures a sufficient flow rate of the cutting fluid. FIG. 4 shows a twist drill with an oil hole according to another embodiment of the present invention, which is an example of a blade drill to which a cutting edge tip 5 is brazed and joined. Although the case where the twist is stronger than the above is shown, it is basically the same as the above. The difference is that the positions of the two main pipes 8 constituting the oil hole 7 are different, and the hole depth of the main pipe 8 is slightly shallow. The branch pipe 9 is correspondingly longer. By responding in this manner, the oil hole 7 can be set for a drill having a twist angle of up to about 20 ° in a twist drill having an oil hole of a normal length. [0011] The twist drill with an oil hole of the present invention,
Of the main pipe and branch pipes constituting the oil hole, the main pipe is formed as two straight holes parallel to the rotation axis, so that a sufficient amount of cutting fluid can be supplied without reducing the sectional area of the chip discharge groove. Will be able to secure. Coupled with the short length of the branch pipe, there is no difficulty in manufacturing the oil hole.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows one embodiment of the present invention, (a) is a front view of a drill, and (b) is a side view. FIG. 2 is a sectional view taken along line AA of FIG. FIG. 3 is a sectional view taken along line BB of FIG. 1; 4 (a) is a front view of a drill, and FIG. 4 (b) is a side view showing another embodiment of the present invention. FIG. 5A is a front view and FIG. 5B is a side view showing a conventional twist drill with an oil hole. FIG. 6 is a sectional view taken along line AA of FIG. 7A is a front view and FIG. 7B is a side view showing another conventional twist drill with an oil hole. FIG. 8 is a sectional view taken along line AA of FIG. 7; [Description of Signs] 4 Chip discharge groove 5 Cutting edge chip 7 Oil hole 8 Main pipe 9 Branch pipe

Claims (1)

Claims: 1. A twist drill with an oil hole, wherein two chip discharge grooves with a twist around the rotation axis are formed, and an oil hole is formed inside the main body along the rotation axis. In the above, the oil hole communicates with each of the main pipe formed of two blind holes formed in parallel with the rotation axis from the rear end of the drill body toward the front end, and the main pipe from the front end of the drill body. A twist drill with an oil hole, characterized in that the twist drill is constituted by a branch pipe which is formed.