JPH0533202Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a drill in which a chip discharge groove extending from the tip to the rear end is formed on the outer periphery of the drill body.

[Prior art and its problems] Conventionally, as this type of drill, for example, a gun drill is known. The gun drill has a chip discharge groove formed on the outer periphery of the drill body, and a cutting edge formed at the intersection of the wall surface facing the rotation direction of the chip discharge groove and the tip flank.

By the way, with drills for drilling deep holes, such as the gun drill mentioned above, the drill body is long, so the drill body tends to undergo elastic deformation such as twisting or bending due to cutting resistance. The main unit vibrates. For this reason, not only the precision of the machined hole and the surface roughness deteriorate, but also accidents such as breakage of the cutting edge occur frequently. Therefore, in conventional gun drills, the feed amount is minimized to reduce the cutting resistance, but this has resulted in the problem of extremely poor drilling efficiency.

This invention was made in order to solve the above-mentioned problems, and the purpose is to provide a drill that has low cutting resistance and is therefore capable of heavy cutting even in deep hole drilling.

[Means for solving the problem] This invention has the following configuration in order to achieve its purpose. That is, four chip discharge grooves 7 extending from the tip to the rear end are formed on the outer circumference of the drill body 1, and a pair of chip discharge grooves 7 are formed facing each other with the center of rotation of the drill body 1 interposed therebetween.
A pair of first cutting edges 16 extending from the outer periphery to the center of the drill body 1 are formed at the intersection of the wall surface 7a facing the rotation direction and the tip flank 13, and another pair of the chip discharge grooves are formed. At the intersection of the wall surface 7a facing the rotation direction of the drill body 1 and the tip flank surface 10, a second cutting edge is provided which extends from the outer periphery of the drill body 1 toward the center and is shorter in length than the first cutting edge 16. A blade 11 is formed, and the tip flank surface 10 of the second cutting blade 11 has a range that is continuous with the chip discharge groove 7 and is forward of the extension line of the second cutting blade 11 in the rotational direction. It is characterized by having a notch 12 formed therein.

[Function] In the drill with the above configuration, four cutting edges are formed at the tip of the drill body, and some of the cutting edges are shorter than other cutting edges, so the drill The first of the four cutting blades is located in the center of the main body.
Only the cutting edge exists, and it is possible to form a notch that extends from the tip flank to the area beyond the extension line of the second cutting edge, and the chips generated by cutting by the first cutting edge in the center. can be discharged smoothly, and cutting resistance is therefore reduced.

In addition, since only the first cutting edge of the four cutting edges mentioned above exists in the center of the drill body, only the first cutting edge is involved in cutting when drilling starts. The biting thrust at the start can be reduced.

[Embodiment] FIGS. 1 to 6 are diagrams showing an embodiment of the present invention.

In FIG. 1, reference numeral 1 indicates a drill body. The drill body 1 has a cylindrical shape and is composed of a shank 2 and a chip 3 fixed to the shank 2 by brazing. The chip 3 is made of cemented carbide and has a small diameter portion 4 formed at the tip and a large diameter portion 5 formed at the rear end.
It is composed of. A recess 6 is formed between the small diameter portion 4 and the large diameter portion 5.

Furthermore, four chip discharge grooves 7 extending from the tip toward the rear end are formed on the outer circumference of the drill body 1. The chip discharge groove 7 has a V-shaped cross section, and has a wall surface 7a facing the direction of rotation and the small diameter portion 4.
Side cutting edges 8 and 9 are formed at the intersections of the large diameter portion 5 with the outer circumferential surfaces 4a and 5a, respectively. The side cutting edge 8 on the side of the small diameter portion 4 is provided with a back taper of 0.04 to 0.06 mm per 100 mm of length.

Furthermore, a cutting edge 11 (second cutting edge) is provided at the intersection of the tip flank surface 10 and the wall surface 7a facing the rotation direction of the pair of chip discharge grooves 7, 7 facing each other with the center of rotation of the drill body 1 in between. A notch 12 is formed in the tip flank 10 at a portion extending from the bottom 7b of the chip discharge groove 7 formed at the rear in the direction of rotation toward the rotation center of the drill body 1. A wall surface 12a of the notch 12 facing the rotation direction is continuous with a wall surface 7a of the chip discharge groove 7 facing the rotation direction.

Due to the notch 12, the cutting edge 11 is formed by a predetermined length from the outer periphery of the drill body 1 toward the center.

Further, a chisel edge 14 is formed at the center of the tip of the drill body 1, which is the intersection of the tip flanks 13, 13 located perpendicular to the cutting edges 11, 11. Further, thinnings 15 are provided at the intersections of the tip flank 13 and the wall surfaces 7a and 12a of the chip discharge groove 7 and the notch 12 facing in the rotational direction. A cutting edge 16 (first cutting edge) extending from the end of the chisel edge 14 to the outer periphery of the drill body 1 is formed at the intersection of the wall surface defining the thinning 15 and the tip flank.

Note that the reference numeral 17 in the figure indicates that the chip 3 is connected to the shank 2.
This is a hole for letting out air when brazing and fixing.

In the case of a drill having such a configuration, the four tip flanks 10, 10, 13, 13 of the drill body 1 are
Since cutting edges 11 and 16 are formed respectively on the
The amount of cutting per cutting edge 10, 16 can be reduced during drilling. Therefore, cutting resistance can be reduced, and heavy cutting can be performed even in deep hole machining. In addition, as a result of forming the notch 12 extending from the bottom 7b of the chip discharge groove 7 toward the rotation center side of the drill body 1 in the tip flank 10, the central part of the drill body 1 has the above-mentioned
Since only the cutting edge 16 exists among the two cutting edges 11 and 16, only the cutting edge 16 is involved in cutting at the start of hole machining, so that the biting thrust at the start of the machining can be reduced. Furthermore, since the chip 3 is composed of a small diameter part 4 and a large diameter part 5, and side cutting edges 8 and 9 are formed on each of them, the hole machined by the small diameter part 4 is formed in the large part 5. Therefore, finishing machining can be performed, and reaming after drilling is not necessary, and the cost of drilling can be reduced.

Further, as shown in FIGS. 7 to 10, if an oil hole 18 is formed in the drill body 1, one end of which opens into the tip flanks 13, 13 and the walls of the notches 12, 12, the deep part of the machined hole Since a sufficient amount of cutting oil can be supplied to the machine, not only heavy cutting can be performed, but also chips can be forcibly discharged.

[Effects of the invention] As explained above, the drill of this invention has four chip discharge grooves extending from the tip to the rear end formed on the outer periphery of the drill body, and facing each other across the center of rotation of the drill body. At the intersection of the wall surface facing the rotation direction of the pair of chip evacuation grooves and the tip flank, there is a pair of first grooves extending from the outer periphery to the center of the drill body.
At the intersection of the wall surface facing the rotational direction of the other pair of chip evacuation grooves and the tip flank, a cutting edge extending from the bottom of the outer periphery of the drill body toward the center and starting from the first cutting edge is formed. A second cutting edge with a shorter length is formed, and a notch is formed in a wide range extending from the tip flank to an area beyond the extension line of the second cutting edge, so that this notch can be easily accessed. Chips can be received and further guided through the chip discharge groove, so chips can be smoothly discharged in the center and cutting resistance is reduced. Since the amount of cutting required for hole drilling is thus small, heavy cutting can be performed even in deep hole drilling, and the effect that the work efficiency of drilling can be significantly improved can be obtained.

[Brief explanation of the drawing]

1 to 6 are views showing one embodiment of the present invention, in which FIG. 1 is a side view showing a drill, and FIG. 2 is a side view showing a drill.
The figure is a sectional view taken in the direction of Fig. 1, Fig. 3 is a sectional view taken along the - line in Fig. 1, Fig. 4 is a sectional view taken in the - line in Fig. 1, and Fig. 5 is a sectional view taken in the - line in Fig. 2. Sectional view, No. 6
The figure shows the details of the chisel edge part in FIG. 2, and FIGS. 7 to 10 are side views showing the drill, and FIG.
9 is a sectional view taken along the - line in FIG. 7, and FIG. 10 is a sectional view taken along the - line in FIG. 7. 1... Drill body, 4a... Outer circumference, 5a...
Outer periphery, 7...Chip discharge groove, 7a...Wall surface, 10
... Tip flank surface, 11 ... Cutting blade (second cutting blade),
13... Tip flank surface, 16... Cutting blade (first cutting blade).

Claims (1)

[Scope of utility model registration request] Four chip discharge grooves 7 extending from the tip to the rear end are formed on the outer periphery of the drill body 1, and the rotation direction of the pair of chip discharge grooves 7 facing each other across the rotation center of the drill body 1 is A pair of first cutting edges 16 extending from the outer periphery to the center of the drill body 1 are provided at the intersection of the facing wall surface 7a and the tip flank surface 13.
At the same time, at the intersection of the wall surface 7a facing the rotational direction of the other pair of chip discharge grooves 7 and the tip flank surface 10, a groove extending from the outer periphery of the drill body 1 toward the center and forming the first A second cutting edge 11 having a shorter length than the cutting edge 16 is formed, and the tip flank surface 10 of the second cutting edge 11 is provided with the chip discharge groove 7.
A drill characterized in that a notch 12 is formed which is continuous with the second cutting edge 11 and reaches a range forward in the rotational direction from the extension line of the second cutting edge 11.