JP5811919B2 - Drill with coolant hole - Google Patents

Description

  In the present invention, a chip discharge groove spirally twisted is formed on the outer periphery of the tip of the drill body, and the land formed between the chip discharge grooves in the circumferential direction has the same direction as the chip discharge groove. The present invention relates to a drill with a coolant hole in which a coolant hole to be twisted is formed.

  As such a drill with a coolant hole, for example, Patent Document 1 discloses that two coolants arranged at different radial distances from the center axis of the drill body in a shank part on the rear end side of the drill body in a blade-tip replaceable drill. There has been proposed one in which the hole is formed so as to communicate with a spirally twisted coolant hole on the tip side of the drill body, which is also arranged at different distances from the center axis of the drill body.

JP-A-8-252709

  However, if the coolant hole extends in a spiral manner on the tip end side of the drill body and opens at the tip flank in this way, the actual length along the twist of the coolant hole per unit length in the axial direction Becomes longer, and the coolant discharge flow rate from the opening portion of the tip flank becomes smaller due to the resistance with the inner peripheral surface of the coolant hole. For this reason, it becomes impossible to supply coolant efficiently to the part to be cut on the bottom surface of the cutting edge or the processed hole of the workpiece, which may increase the cutting resistance or cause chip welding.

  The present invention has been made under such a background, and it is possible to increase the coolant discharge flow rate from the coolant hole opening portion of the tip flank and to provide a coolant hole with an efficient coolant supply. The purpose is to provide.

In order to solve the above-described problems and achieve such an object, the present invention provides a drill rotation direction toward the rear end side from the tip of the drill body to the outer periphery of the tip of the drill body rotated about the axis. A chip discharge groove that twists rearward is formed, a cutting blade is formed at the tip of the wall surface of the chip discharge groove facing the drill rotation direction, and between the chip discharge grooves in the circumferential direction of the tip of the drill body. In the land portion to be formed, a coolant hole that is twisted in the same direction as the chip discharge groove is formed from the rear end to the front end side of the drill body, and the coolant hole is formed with the cutting edge. in near the tip portion of the drill body has been allowed to open in the tip flank of the drill body extends linearly, the cross-sectional area of the coolant holes in the vicinity of the tip portion, the rear end side from the tip vicinity Characterized in that there is a small and less than 1/2 of the cross-sectional area of該捩the coolant hole than the cross-sectional area of the coolant hole twisted in the portion.

  In the drill with the coolant hole configured as described above, the coolant hole is formed so as to be twisted in the same direction as the chip discharge groove from the rear end to the tip side of the drill body, but the cutting blade is formed. In the vicinity of the tip of the drill body, it extends linearly and is open to the tip flank. Therefore, in the vicinity of the tip of the drill body, the length of the coolant hole is shortened as compared with the case where it extends while being twisted. The resistance between the coolant and the coolant hole inner peripheral surface can be reduced.

  For this reason, the coolant discharge flow rate from the coolant hole opening at the tip flank can be increased, and the coolant can be efficiently supplied to the part to be cut on the bottom surface of the cutting edge or workpiece to be lubricated. Therefore, it is possible to cool, reducing cutting resistance and preventing chip welding. Further, chips can be discharged smoothly from the processing hole.

In the present invention, the cross-sectional area of the coolant hole in the vicinity of the tip is made smaller than the cross-sectional area of the twisted coolant hole in the portion on the rear end side from the vicinity of the tip. It is possible to prevent the coolant flow rate and supply pressure from being lowered and to supply coolant efficiently. Incidentally, the cross-sectional area of the coolant hole twisted in the vicinity of the tip portion, are you least 1/2 of the cross sectional area of the coolant holes twisted said in the portion of the rear end side from the vicinity of the tip portion is smaller than this This is because there is a risk that the resistance increases in supplying the coolant in the vicinity of the tip .

  The coolant hole may be circular in cross section, but at least in the portion from the vicinity of the tip to the rear end, the coolant hole has a triangular cross section that becomes wider in the circumferential direction toward the outer peripheral side of the drill body. By doing so, it becomes possible to efficiently supply the coolant that receives pressure on the outer peripheral side due to the centrifugal force caused by the rotation of the drill body to the vicinity of the tip.

  Further, the entire drill body may be formed of a hard material such as a cemented carbide, but the drill body is formed of an ultra-high pressure sintered body in the vicinity of the tip, and the rear end side from the tip vicinity is formed. If the drill body is formed of cemented carbide in the part, the hardness of the drill body in the part near the tip to the rear end side is ensured while the hardness of the part near the tip where the cutting blade is formed is further increased It is possible to perform drilling even on the workpieces and difficult-to-cut materials.

  As described above, according to the present invention, the length of the coolant hole in the vicinity of the tip of the drill body is shortened, the resistance between the coolant and the coolant hole inner peripheral surface is reduced, and the coolant discharge flow rate is increased. Since efficient coolant supply can be achieved, cutting resistance can be reduced, chip welding can be prevented, and smooth chip discharge can be promoted.

It is a partial side view which shows one Embodiment of this invention (illustration is abbreviate | omitted in the rear end side of the shank part). It is AA sectional drawing in FIG. It is BB sectional drawing in FIG. It is sectional drawing equivalent to BB sectional drawing in FIG. 1 which shows the 1st modification of embodiment shown in FIG. It is a front view which shows the 2nd modification of embodiment shown in FIG. It is a front view which shows the 3rd modification of embodiment shown in FIG.

  1 to 3 show an embodiment of the present invention. In this embodiment, the drill body 1 has a substantially cylindrical outer shape centered on the axis O, the rear end side portion (the right side portion in FIG. 1) is a shank portion 2, and the tip is more distal than the shank portion 2. The side portion (left side portion in FIG. 1) is a cutting edge portion 3, and the shank portion 2 is gripped by the main shaft of the machine tool and rotated around the axis O in the drill rotation direction T, and sent to the tip side in the axis O direction. As a result, the workpiece is perforated by the cutting blade portion 3.

  In the cutting edge portion 3, a pair of chip discharge grooves 4 that are twisted to the rear side in the drill rotation direction T about the axis O as it goes from the front end to the rear end side of the drill body 1 are formed at equal intervals in the circumferential direction. Furthermore, the tip of the wall surface of the chip discharge groove 4 facing the drill rotation direction T extends from the vicinity of the axis O at the tip of the drill body 1 to the outer periphery at the intersection ridge line portion with the tip flank 5 at the tip of the drill body 1. A cutting edge 6 is formed.

  The drill main body 1 is also formed with a pair of coolant holes 7 extending from the rear end of the shank portion 2 to the front end side and opening to the front end flank 5. These coolant holes 7 are formed in the chip discharge groove 4 in the circumferential direction of the drill body 1 in a portion of the cutting edge portion 3 excluding the tip vicinity portion 3 a having a predetermined length in the axis O direction from the tip of the drill body 1. Drill rotation direction T as it goes to the rear end side with a lead that is formed on the land portion 8 formed between them and is equivalent to the twisted lead of the chip discharge groove 4 along one virtual cylindrical surface centered on the axis O The shank portion 2 is also twisted with the same lead and opened at the rear end surface of the drill body 1.

  On the other hand, the coolant hole 7a in the tip vicinity portion 3a extends straight from the tip of the twisted coolant hole 7 in the rear end side portion than the tip, and is opened to the tip flank 5. . In the present embodiment, the coolant hole 7a in the tip vicinity portion 3a is a chip in the tip vicinity portion 3a along a tangential plane to the virtual cylindrical surface extending along the twisted coolant hole 7 on the rear end side. In the second flank 5b adjacent to the rear side of the drill rotation direction T of the first flank 5a extending to the cutting edge 6 of the tip flank 5 and extending in a slant so as to match the twist of the discharge groove 4, the direction of the axis O As viewed, it is opened from the axis O in the radial direction at a position about half the length of the cutting edge 6.

  In the present embodiment, the coolant hole 7a in the tip vicinity portion 3a is substantially circular in cross section as shown in FIG. 2, whereas the twisted coolant hole 7 on the rear end side from the tip vicinity portion 3a is shown in FIG. As shown in FIG. 2, the cross section is formed in a substantially triangular shape that becomes wider in the circumferential direction toward the outer peripheral side of the drill body 1. Moreover, in this embodiment, as shown in FIGS. 2 and 3, in the cross section orthogonal to the axis O, the cross-sectional area of the coolant hole 7a in the tip vicinity portion 3a is the coolant in the portion on the rear end side from the tip vicinity portion 3a. The cross-sectional area of the hole 7 is made smaller.

  Further, in the present embodiment, the drill body 1 is formed of an ultra-high pressure sintered body such as a diamond sintered body or a cBN sintered body in the tip vicinity portion 3a, while a portion on the rear end side from the tip vicinity portion 3a. Is made of cemented carbide. In addition, the tip vicinity part 3a of such a drill main body 1 is made into the length of the range of the outer diameter (diameter) of the cutting edge 6 from the most advanced end of the drill main body 1, and is made from the cemented carbide of the rear end side from this. In this embodiment, the boundary P with this portion is a plane perpendicular to the axis O.

  Such a drill with a coolant hole, for example, separately manufacture a portion that becomes the tip vicinity portion 3a of the drill body 1 and a portion on the rear end side from this separately by an ultra-high pressure sintered body and a cemented carbide, respectively. It is possible to manufacture by bonding these by diffusion bonding such as brazing or friction welding. A coolant hole 7 having a triangular cross section spirally twisted by extrusion molding of a cemented carbide material is formed in a portion on the rear end side from the tip vicinity portion 3a, and is sintered and joined to the tip. A coolant hole 7a that extends linearly by electric discharge machining may be formed in a portion that becomes the tip vicinity portion 3a to communicate with the tip of the twisted coolant hole 7.

  For example, in the drill with a coolant hole having the above-described configuration manufactured as described above, the coolant hole 7 that is spirally twisted from the tip vicinity portion 3a to the rear end side extends linearly at the tip vicinity portion 3a and extends to the tip clearance surface. 5, the length of the coolant hole 7a can be made shorter in the vicinity of the tip 3a than in the case where it is still twisted. Therefore, the resistance received from the inner peripheral surface of the coolant hole 7a when the coolant flows in the coolant hole 7a can be reduced, and the flow velocity when the coolant is discharged from the opening to the tip flank 5 can be increased. it can.

  For this reason, it becomes possible to supply efficient coolant to the cutting edge 6 and the part to be cut on the bottom surface of the processed hole of the workpiece to be cut by the cutting edge 6. Can be lubricated and cooled. Therefore, according to the coolant hole drill having the above-described configuration, it is possible to reduce the cutting resistance at the time of drilling and reduce the rotational driving force of the drill main body 1 and to reduce the cutting edge 6 and the part to be cut or the cutting edge. Chip welding due to high temperature of the chips generated by the blade 6 can be prevented. In addition, it is possible to promote smooth discharge of chips by improving the coolant discharge flow rate.

Further, in the present embodiment, the cross-sectional area of the coolant hole 7a in the tip vicinity portion 3a is made smaller than the cross-sectional area of the twisted coolant hole 7 in the portion on the rear end side from this, thereby the tip vicinity portion 3a. In this case, the coolant supply pressure is increased to increase the discharge flow velocity, so that the coolant can be supplied more efficiently. However, if the cross-sectional area of the coolant hole 7a in the tip vicinity portion 3a becomes too small, the resistance becomes too high and the discharge flow rate and the coolant supply amount may be reduced. Therefore, the coolant hole 7a in the tip vicinity portion 3a The cross-sectional area is set to 1/2 or more of the cross-sectional area of the twisted coolant hole 7 on the rear end side from the front end vicinity portion 3a .

  Further, in the present embodiment, the coolant hole 7a has a circular cross section in the vicinity of the front end portion 3a, whereas the cross section of the twisted coolant hole 7 on the rear end side from the front end vicinity portion 3a is on the outer peripheral side of the drill body 1. It is formed in a substantially triangular shape whose width in the circumferential direction becomes wider as it goes. For this reason, the coolant supplied to the front end side while receiving the centrifugal force due to the rotation of the drill body 1 during drilling and receiving pressure on the outer peripheral side is caused by the coolant hole 7 having a triangular cross section which is wide on the outer peripheral side. It can supply efficiently and can be made to discharge from the coolant hole 7a of the front-end | tip vicinity part 3a.

  In this embodiment, the coolant hole 7a in the tip vicinity portion 3a has a circular cross section, but the coolant hole 7a also has a circumferential direction as the cross section toward the outer peripheral side of the drill body 1 in the same manner as the twisted coolant hole 7. It may be a triangular shape that is wide. For example, when forming the coolant hole 7a in the tip vicinity portion 3a by electric discharge machining as described above, the coolant hole 7a becomes wider in the circumferential direction as the electric discharge machining electrode has a triangular cross-section toward the outer peripheral side. What is necessary is just to form.

  On the other hand, the cross-sectional view corresponding to the BB cross section in FIG. 1 is also twisted coolant from the vicinity of the front end portion 3a to the rear end side, as in the first modification of the embodiment shown in FIG. The cross section of the hole 7 may be substantially circular like the coolant hole 7a in the tip vicinity portion 3a. In this case, the straight coolant hole 7a in the vicinity of the front end portion 3a and the twisted coolant hole 7 on the rear end side from the front end vicinity portion 3a are relatively easily communicated on the same axis, and the coolant is twisted. It is possible to prevent the coolant holes 7 from being biased and supplied to the linear coolant holes 7a.

  Furthermore, in this embodiment, while the tip vicinity part 3a of the drill main body 1 in which the linear coolant hole 7a is formed is formed by an ultra-high pressure sintered body such as a diamond sintered body or a cBN sintered body, A portion where the twisted coolant hole 7 on the rear end side from the tip vicinity portion 3a is formed is made of cemented carbide. For this reason, the tip vicinity portion 3a where the cutting edge 6 is formed can be made harder, so that it is possible to surely perform drilling even for a high-hardness workpiece or difficult-to-cut material.

  However, also about this, the whole drill main body 1 may be formed with the cemented carbide. In such a case, the coolant hole 7a is formed in a straight line shape in the vicinity of the tip 3a of the drill body 1, and the twisted coolant hole 7 is formed on the rear end side in the same manner as described above. The proximal portion 3a and the rear end side portion are manufactured separately from cemented carbide, and a twisted coolant hole 7 is formed in the rear end side portion, and these are joined together. The straight coolant hole 7a may be formed in the tip vicinity portion 3a by electric discharge machining or the like.

  Furthermore, in this embodiment, the straight coolant hole 7a is the length of the cutting edge 6 in the radial direction from the axis O in the second flank 5b of the tip flank 5 of the drill body 1 when viewed in the direction of the axis O. However, the length of the cutting edge 6 in the radial direction from the axis O is viewed in the direction of the axis O as in the second modification shown in FIG. The opening 6 is opened at a position on the inner peripheral side than 1/2, or conversely, the length of the cutting blade 6 is 1 in the radial direction from the axis O as viewed in the direction of the axis O as in the third modification shown in FIG. It may be opened at a position on the outer periphery side than / 2.

  In these modifications, the length of the linear coolant hole 7a is slightly longer than in the above embodiment, but in the second modification, the coolant is discharged from the inner peripheral side of the tip of the drill body 1 and centrifuged. Since it spreads to the outer peripheral side by force, the coolant can be uniformly supplied to the cutting edge 6 and the part to be cut. On the other hand, in the third modified example, since the linear coolant hole 7a extends and opens toward the outer peripheral side toward the tip side, the coolant discharge flow rate can be further increased by centrifugal force, and more efficient coolant can be obtained. Supply.

DESCRIPTION OF SYMBOLS 1 Drill main body 3 Cutting edge part 3a Tip vicinity part 4 Chip discharge groove 5 Tip flank 6 Cutting edge 7 Coolant hole (twisted coolant hole)
7a Linear coolant hole 8 Land O Drill body 1 axis T Drill rotation direction

Claims (3)

A chip discharge groove is formed on the outer periphery of the tip of the drill body that rotates about the axis, and twists toward the rear side in the drill rotation direction from the tip of the drill body toward the rear end. A cutting edge is formed at the front end of the facing wall, and a land portion formed between the chip discharge grooves in the circumferential direction of the tip end portion of the drill body has the above-mentioned direction from the rear end of the drill body toward the front end side. A coolant hole that is twisted in the same direction as the chip discharge groove is formed, and this coolant hole extends linearly in the vicinity of the tip of the drill body where the cutting blade is formed, and the tip flank of the drill body Is opened to
The cross-sectional area of the coolant hole in the vicinity of the tip is smaller than the cross-sectional area of the twisted coolant hole in the portion on the rear end side from the vicinity of the tip, and is ½ or more of the cross-sectional area of the twisted coolant hole. coolant holes drill, characterized in that there is a. 2. The coolant hole according to claim 1 , wherein the coolant hole has a triangular cross-section that becomes wider in the circumferential direction toward the outer peripheral side of the drill body at least in a portion from the vicinity of the front end to the rear end side. With drill. The drill body in the vicinity of the tip portion is formed by ultrahigh pressure sintered material, or claim 1 wherein the drill body in the portion of the rear end side from the tip vicinity, characterized in that it is formed by a cemented carbide The drill with a coolant hole according to claim 2 .

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