JPH11245119A - Drill tap - Google Patents

Abstract

PROBLEM TO BE SOLVED: To certainly and promptly discharge chip generated by a drill cutting edge or a tap cutting edge and to provide high sharpness for the tap cutting edge, thereby to improve threaded hole accuracy and to reduce resistance. SOLUTION: The drill tap is provided with a drill cutting edge at the ridge intersection of a wall surface, facing the tool rotational direction T of a chips discharging groove 15 formed so as to extend from the front end to the rear end at the outer periphery part of a tool body 11 which rotates around the axis O and the front end flank of the tool body 11, and a tap cutting edge 20 at the ridge-intersection of the wall surface, facing the tool rotational direction T of a sub chips discharging groove 16 formed on the rear side in the tool rotational direction of the chips discharging groove 15 and the outer peripheral surface of the tool body 11. The tool body 11 is drilled for a cutting fluid feeding hole 21, and the front end of the cutting fluid feeding hole 21 is open in the front end flank. The tap cutting edge 20 is formed so as to have a rake angle θ of 0 deg. or a value in the positive radial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drill tap for drilling and tapping a work material mainly made of a soft material such as an aluminum alloy or a brittle material such as various cast irons.

[0002]

2. Description of the Related Art As such a drill tap, for example, those shown in FIGS. 4 to 6 are known. The drill tap shown in these figures is
The tool body 1 is provided on an outer peripheral portion of a cylindrical shaft-shaped tool body 1 which is rotated around an axis O.
The chip discharge grooves 3, 3 extending toward the rear end side while being twisted to the rear side in the tool rotation direction T from the front end flank 2 are formed, and the wall surfaces of the chip discharge grooves 3, 3 facing the tool rotation direction T are formed. A drill bit 4 is formed at the intersection ridge line with the tip flank 2, and a sub-chip discharge groove 5 is formed behind the chip discharge groove 3 in the tool rotation direction T. A tap blade 6 is formed at the intersection ridge line between the wall surface of the groove 5 facing the tool rotation direction T and the outer peripheral surface of the tool body 1. However, in such a drill tap, while rotating the tool main body 1 around the axis O in the tool rotation direction T, the feed per rotation is equal to the pitch of the tap blades 6, and the tool is sent to the tip side in the axis O direction. Thus, a screw can be formed by the tap blade 6 on the inner periphery of the machined hole drilled by the drill blade 4 at the tool tip, so that the drilling of the work material and the tapping can be performed simultaneously. Can be.

[0003]

Here, in this conventional tap drill, the chips generated by the drill blade 4 are sent to the tool rear end side through the chip discharge groove 3 connected to the drill blade 4. While being discharged, the chips generated by the tap blade 6 are discharged through the sub chip discharge groove 5. However, in the tap drill, the feed of these chips to the rear end side of the tool is based only on the effect of pushing out the chip discharge groove 3 and the auxiliary chip discharge groove 5 twisted around the axis O with the rotation of the tool body 1. Therefore, for example, when feeding the tool body 1 downward to the work material, it is difficult to reliably and promptly discharge the chips,
Chips may be clogged to increase the resistance, and in some cases, the tool body 1 may be broken. Further, in the conventional drill tap, as shown in FIGS. 5 and 6, a rake angle and a hook angle given to the tap blade 6,
That is, since the radial rake angle θ is a negative angle, the sharpness of the tap blade 6 is inevitably dull, and the precision of the formed screw hole is impaired, and the resistance is further increased. There was also a problem of inviting. In addition, these problems become more remarkable when the work material is a soft material or a brittle material as described above.

[0004] The present invention has been made under such a background. The present invention reliably and promptly discharges chips generated by a drill blade and a tapping blade, and gives a sharp cutting edge to the tapping blade to improve the precision of a screw hole. The purpose is to improve and reduce the resistance.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems and achieve such an object, the present invention provides a method in which an outer peripheral portion of a tool body which is rotated about an axis is provided from the tip of the tool body. A chip discharge groove extending toward the end is formed, and a drill blade is formed at an intersection ridge portion of a wall surface of the chip discharge groove facing the tool rotation direction and a flank of the leading end of the tool body, while a chip discharge groove of the chip discharge groove is formed. A sub-chip discharge groove is formed on the rear side in the tool rotation direction, and a tap blade is formed at an intersection ridge portion of a wall surface of the sub-chip discharge groove facing the tool rotation direction and an outer peripheral surface of the tool main body. In the drill tap, a supply hole for the cutting oil was drilled in the tool body, and the tip of the supply hole was opened in the flank of the tip, and the tap blade was given a 0 ° or positive rake angle in the radial direction. It is characterized by the following.

Therefore, according to such a drill tap, the cutting oil sprayed from the flank of the tool body through the supply hole passes through the chip discharge groove and the sub chip discharge groove to the tool rear end side. As the chips are ejected, the chips generated by the drill and tap blades are also pushed out toward the rear end of the tool, preventing chips from accumulating in the chip discharge groove and sub chip discharge groove and causing chip clogging. Can be. On the other hand, since the tap blade is provided with 0 ° or a positive rake angle in the radial direction, the sharpness thereof can be sharpened, the screw hole accuracy can be improved, and the tapping resistance can be improved. Can be reduced. Moreover, since the tap blade is given a 0 ° or positive rake angle in the radial direction as described above, the chips generated by the tap blade are generated along the wall surface of the sub chip discharge groove toward the tool inner peripheral side. Since the cutting fluid passes through the sub chip discharge groove, the cutting oil is reliably pushed to the rear end side of the tool, so that the chips can be discharged more quickly.

In the case where the chip discharge groove and the sub chip discharge groove are formed so as to be twisted around the axis toward the rear side in the tool rotation direction toward the rear end side of the tool, Due to the pushing effect caused by the rotation, the chips can be more reliably and promptly discharged. In this case, the supply hole is formed so as to be twisted in accordance with the torsion of the chip discharge groove and the sub chip discharge groove, thereby securing a large sectional area in the supply hole while maintaining the rigidity of the tool body. This makes it possible to reliably supply a sufficient amount of cutting fluid to discharge chips.

[0008]

FIG. 1 to FIG. 3 show an embodiment of the present invention. In the drill tap of this embodiment, the tool body 11 is formed in a substantially cylindrical shaft shape from a hard material such as a cemented carbide, and the rear end of the tool body 11 is a shank portion 12 and the tip side is a blade portion. 13 is set. The blade portion 13 is twisted rearward in the tool rotation direction T around the central axis O of the tool main body 11 from the front end flank 14 facing the front end side of the tool main body 11 toward the rear end side. A pair of extending chip discharge grooves 15, 15 and a pair of sub-chip discharge grooves 16, 16 which are located on the rear side of the chip discharge grooves 15, 15 in the tool rotation direction T and are similarly twisted, respectively, have an axis O. Are formed so as to be axially symmetric with respect to each other. Of these, the tool is formed on the intersection ridge line between the wall surface of the chip discharge grooves 15, 15 facing the tool rotation direction T and the tip flank 14, toward the tool outer peripheral side. Drill blades 17 are formed so as to be inclined toward the rear end side.

A land portion 18 defined between the chip discharge grooves 15 and 15 in the circumferential direction on the outer periphery of the blade portion 13 is formed at a portion connected to the tool rotation direction T from the sub chip discharge groove 16. On the other hand, a portion continuing from the sub-chip discharge groove 16 to the rear side in the tool rotation direction T is formed such that the width in the circumferential direction and the outer diameter from the axis O are larger. On the outer peripheral surface having a large diameter at the land portion 18 which continues from the rear side in the tool rotation direction T, a plurality of threads which are twisted in accordance with the pitch of the screws of the screw holes to be formed by the drill tap and the lead. .. Are formed, and a tap blade 20 is formed at an intersection ridge portion between these screw threads 19 and the wall surface of the sub chip discharge groove 16 facing the tool rotation direction T. In the present embodiment, the wall surface of the sub chip discharge groove 16 facing the tool rotation direction T is directed rearward in the tool rotation direction T from the tap blade 20 on the tool outer circumference toward the tool inner circumference. The tap blade 20 is provided with a positive radial rake angle θ as shown in FIGS. 2 and 3.

In the present embodiment, the circumferential width of the sub-chip discharge groove 16 is formed smaller than the circumferential width of the chip discharge groove 15, and the depth of the sub-chip discharge groove 16 is also reduced. The chip discharge groove 15 is formed to be smaller than the groove depth. Further, in the present embodiment, a pair of cutting oil supply holes 21 that are twisted around the axis O at intervals from the axis O from the rear end surface of the shank portion 12 to the blade portion 13 in the tool body 11. , 21 are bored axially symmetrically with respect to the axis O.
Is twisted in the blade portion 13 in accordance with the twist of the chip discharge grooves 15, 15 and the sub chip discharge grooves 16, 16 so that the tool inner peripheral side of the groove bottom of the sub chip discharge grooves 16, 16 in the lands 18, 18 is rotated. As shown in FIG.

However, in the drill tap configured as described above, first, the supply holes 21 and 21 for the cutting oil are drilled in the tool body 11 from the rear end face of the shank portion 12 thereof. Reference numeral 21 denotes an opening at the tip flank 14 at the tip of the tool body 11, so that the supply holes 21 and 21 are provided from the side of the machine tool gripping the shank portion 12.
The cutting fluid supplied to the tool is ejected from the front flank 14 into the machining hole, then flows backward through the chip discharge groove 15 and the sub chip discharge groove 16 to the tool rear end side and is discharged from the machining hole. You. When passing through the chip discharge groove 15 and the sub chip discharge groove 16, the cutting oil is pushed out toward the rear end of the tool together with the chip generated by the drill blade 17 and the tap blade 20. According to the tap, it is possible to reliably prevent chips from staying in the chip discharge groove 15 and the sub chip discharge groove 16 to cause chip clogging. Can be prevented beforehand.

On the other hand, in the drill tap having the above-described structure,
The wall surface of the sub-chip discharge groove 16 that is continuous with the tap blade 20 and faces the tool rotation direction T is inclined so as to move toward the rear side in the tool rotation direction T toward the tool inner peripheral side. The direction rake angle θ is given, whereby the sharpness of the tap blade 20 is sharpened, cutting resistance is further reduced, and the accuracy of the formed screw hole can be improved. In addition, since the positive rake angle θ is given to the tap blade 20 in this manner, the chips generated by the tap blade 20 are guided to the tool inner peripheral side along the wall surface of the sub-chip discharge groove 16. As the cutting oil passes through the sub chip discharge groove 16 and is quickly discharged to the rear end side of the tool, according to the present embodiment, the clogging of chips by the tap blade 20 can be further reduced. It is possible to reliably prevent such a problem, for example, the tool body 1
Even when the feed rate of 1 is as high as 0.5 to 2 mm / rev, the screw hole can be smoothly machined and the lubrication effect of the cutting oil further improves the screw hole accuracy. It is possible to encourage.

In this embodiment, the tapping blade 20 is provided with the positive rake angle θ in the radial direction. However, the rake angle θ in the radial direction is set to 0 depending on the material of the work material or the like.
° or more, for example, when the work material is a soft material such as an aluminum alloy, the radial rake angle θ is set to be as large as about 15 ° to 18 ° as a hook angle. On the other hand, when the work material is a brittle material such as cast iron, the radial rake angle θ is desirably set to a small angle of about 0 ° to 8 ° as a rake angle. In the present embodiment, as shown in FIG. 1, the tap blade 20 is formed from a position slightly retreated from the rear end of the drill blade 17 to the rear end side in the direction of the axis O in the direction of the axis O. May be formed so as to be continuous with the rear end of the drill blade 17.

On the other hand, in the present embodiment, the chip discharge groove 1
5 and the auxiliary chip discharge groove 16 are formed in a spiral shape that is twisted rearward in the tool rotation direction T around the axis O as going toward the tool rear end side, and with the rotation of the tool body 11 during machining,
Since the chips are pushed to the tool rear end side by the twist of the chip discharge groove 15 and the sub chip discharge groove 16,
Further, it is possible to promptly discharge chips. And such a chip discharge groove 15 and a sub chip discharge groove 16
In the present embodiment, the supply holes 21 and 21 for the cutting fluid are also formed in the land portion 18 so as to be twisted around the axis O in accordance with the torsion of the tool body 11. Also, a relatively large cross-sectional area can be secured in the supply holes 21 and 21. Therefore, a sufficient amount of the cutting fluid is sufficient to push the chips flowing into the chip discharge groove 15 and the sub chip discharge groove 16 to the tool rear end side. Can be reliably supplied. The supply holes 21 and 2 that are spirally twisted in the tool body 11 made of cemented carbide as in the present embodiment.
In order to form 1, for example, the supply holes 21 and 21 may be formed in advance in a spiral shape before sintering the superhard material, and then sintering may be performed.

[0015]

As described above, according to the drill tap of the present invention, the supply hole for the cutting oil which is opened at the flank of the tip is formed in the tool body, and is provided in the chip discharge groove and the sub chip discharge groove. The flowing chips are quickly pushed out to the rear end side of the tool by this cutting fluid to reliably prevent chip clogging and reduce cutting resistance, and the tap blade has a 0 ° or positive radial rake angle. By being provided, the sharpness of the tap blade is sharpened to promote further reduction of cutting resistance, and it is possible to discharge chips more quickly, thereby improving the screw hole accuracy.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of the present invention.

FIG. 2 is a front view of the embodiment shown in FIG. 1 as viewed from a tool tip side.

FIG. 3 is a sectional view taken along the line ZZ in FIG.

FIG. 4 is a side view showing a conventional drill tap.

5 is a front view of the conventional drill tap shown in FIG. 4 as viewed from a tool tip side.

FIG. 6 is a sectional view taken along the line ZZ in FIG. 4;

[Explanation of symbols]

 Reference Signs List 11 Tool body 14 Tip flank 15 Chip discharge groove 16 Sub chip discharge groove 17 Drill blade 18 Land portion 20 Tap blade 21 Cutting oil supply hole O Center axis of tool body 11 Tool rotation direction θ Rake of tap blade 20 in radial direction Corner

Claims (2)

[Claims] 1. A chip discharge groove extending from a front end to a rear end of the tool main body is formed on an outer peripheral portion of the tool main body that is rotated around an axis, and a wall surface of the chip discharge groove facing the tool rotation direction and the chip discharge groove. A drill blade is formed at the intersection ridge line portion with the tip flank of the tool body, while a sub-chip discharge groove is formed at the rear side in the tool rotation direction of the chip discharge groove, and the tool of the sub-chip discharge groove is formed. In a drill tap in which a tap blade is formed at an intersection ridge line between a wall surface facing in the rotation direction and an outer peripheral surface of the tool body, a supply hole for a cutting oil is drilled in the tool body, and the supply hole is provided. Of the tapping edge is opened at the flank of the tip, and the tap blade has
A drill tap characterized by being given a positive or positive radial rake angle. 2. The chip discharge groove and the sub chip discharge groove,
The supply hole is formed so as to be twisted around the axis toward the tool rotation direction rear side toward the tool rear end side, and the supply hole is also twisted in accordance with the twist of the chip discharge groove and the sub chip discharge groove. The drill tap according to claim 1, wherein: