JPH0150528B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a throw-away drill having a plurality of cutting tips removably attached to the tip of a drill body.

[Prior Art] Examples of conventional drills of this type include those shown in FIGS. 4A and 4B. This drill has two chip discharge grooves 2 and 3 extending from the tip of the outer periphery of the drill body 1 toward the rear end side, spaced approximately 180 degrees apart in the circumferential direction, and the rotation of one of the chip discharge grooves 2. The outer cutting tip 4 that contacts the outer periphery of the drill is placed on the outside of the wall facing the direction, and the outer cutting tip 4 that contacts the outer periphery of the drill
The inner cutter tips 5 that are in contact with the inner cutters are removably glued to each other, and the intermediate cutter tips 6 are detachably attached to the center of the wall surface facing the rotational direction of the other chip discharge groove 3. In the locus, each end in the radial direction is arranged so as to overlap the inner end of the outer cutter tip 4 and the outer end of the inner cutter tip 5, respectively, and the three tips 4, 5, and 6 are aligned with the axis O. A single cutting edge is formed extending from the center to the outer periphery of the drill.

[Problems to be Solved by the Invention] By the way, in the throw-away drill having the above configuration, the outer cutting tip 4 is in contact with the inner periphery of the machined hole.
A large radial load (load in the radial direction) acts on the This radial load bends the drill body, causing problems such as the drill vibrating during drilling, or the drilled hole becoming curved.

[Object of the invention] This invention was made to solve the above problem, and an object of the invention is to provide a throw-away drill that can prevent the drill body from being bent due to radial load. .

[Structure of the Invention] In order to achieve the above object, the present invention arranges an outer cutting tip and an inner cutting tip in one chip discharging groove, and disposing an inner circumferential edge on the other chip discharging groove. The structure is characterized in that an outer cutter tip is arranged on the outer peripheral side end of the inner cutter tip of the chip discharge groove so as to overlap with each other in the rotation locus.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIGS. 1A and 1B show an embodiment of the present invention. The drill shown in this figure differs from the conventional drill described above in that an outer cutting tip 7 is also arranged in the chip discharge groove 3. That is, in the conventional drill described above, the intermediate cutting tip 6 is disposed in the chip discharging groove 3, and is located between the outer cutting tip 4 and the inner cutting tip 5 arranged in the chip discharging groove 2. In this drill, an outer cutting tip 7 is also arranged in the chip discharge groove 3 so as to be in contact with the outer periphery of the drill. Furthermore, the width of the outer cutter tip 7 in the radial direction is larger than that of the outer cutter tip 4, and the inner end thereof overlaps the outer end of the inner cutter tip 5 in the rotation locus.

In the indexable drill having the above configuration, the outer cutting tips 4 and 7 are arranged in the two chip discharge grooves 2 and 3, respectively, and the radial loads acting on these outer cutting tips cancel each other out. Therefore, the drill body 1 is not bent during the drilling process, and it is possible to prevent the drill from vibrating and the drilled hole from becoming bent.

Further, in the drill shown in FIGS. 2A and 2B, the width of the outer cutting tip 8 disposed in the chip discharge groove 2 is smaller than that of the outer cutting tip 4 in the above embodiment,
The inner cutter tip 5 is arranged on the outer peripheral side by that much. As a result, even though the outer cutter tip 9 placed in the chip discharge groove 3 is of the same width as the inner cutter tip 5 placed in the chip discharge groove 2, the inner edge of the outer cutter tip 9 overlaps the outer peripheral side end of the inner cutter tip 5 in the rotation locus. Note that as a result of arranging the inner cutter tip 5 toward the outer circumferential side, the inner cutter tip 5 is spaced apart from the axis O. Therefore,
In the chip discharge groove 3, the outer circumferential end overlaps the inner circumferential end of the inner cutter tip 5 in the rotation locus, and the axis O
The inner cutter tip 10 is arranged so as to be in contact with the inner cutter tip 10.

Furthermore, the drill shown in FIGS. 3A and 3B is a modification of the drill shown in FIGS. 2A and 2B, and uses an equilateral triangular tip as the outer cutter tip 11 disposed in the chip discharge groove 3. be.

[Effects of the Invention] As explained above, according to the indexable drill of the present invention, an outer cutting tip and an inner cutting tip are arranged in one chip discharge groove, and an inner cutting tip is arranged in the other chip discharge groove. Since the outer cutter tip is arranged so that its end overlaps the outer circumferential end of the inner cutter tip of one chip discharge groove in the rotation locus, the radial loads acting on the two outer cutter tips cancel each other out. As a result, the drill body is not bent during drilling, and effects such as being able to prevent the drill from vibrating and the drilled hole from becoming bent can be obtained.

[Brief explanation of drawings]

1, 2, and 3 each show an embodiment of the present invention, in which A is a top view, B is a partially omitted side view, and FIG. 4 is an example of a conventional throw-away drill. , A is a top view thereof, and B is a partially omitted side view thereof. 1... Drill body, 2, 3... Chip discharge groove,
4, 7, 8, 9, 11...Outer cutter tip, 5...Inner cutter tip, O...Axis line.

Claims (1)

[Claims] 1. On the outer periphery of the drill body, two chip evacuation grooves extending from the tip to the rear end are installed approximately in the circumferential direction.
An outer cutting tip that contacts the outer periphery of the drill is removably attached to the outer circumferential side of the wall surface facing the rotation direction of one of the chip evacuation grooves, and is spaced 180 degrees apart. The inner cutting tips spaced apart in the radial direction are removably attached to the outer circumferential side of the wall surface facing the rotation direction of the other chip evacuation groove, the outer circumferential end touches the outer circumference of the drill, and the inner circumferential edge touches the outer circumference of the drill. A throw-away type drill characterized in that an outer cutting tip is detachably attached to the outer circumferential end of an inner cutting tip placed in one of the chip discharge grooves and overlaps in the rotation locus.