JPH02237714A - Drilling tool - Google Patents

Abstract

PURPOSE:To drill a hole without causing reinforcing fibers to produce burrs by forming a cutting edge so that it goes from the base end side to the tip side according as it advances from the inner periphery toward the outer periphery, and keeping rake angle of the cutting edge on a cross section at right angles to the cutting edge at 0 deg. or less. CONSTITUTION:A flat part 2 is formed on a tool body 1, the distance of the flat part from an axis O varies from 5% to 25% of the diameter D, the outer peripheral part 1a is formed into a smooth curved surface, and back taper ranging from 0.4mm to 2mm for 100mm is provided. A cutting edge 3 is tilted at an angle theta to the axis O so that it goes from the base end side to the tip side according as it advances from the inner periphery toward the outer periphery, rake face 4 is formed between the cutting edge 3 and the nose edge of a recessed part 2, a flat face tilted at an angle alpha to a plane including the cutting edge 3 and the axis O when viewed from the direction along the cutting edge 3 is formed, and rake angle alpha on a cross section at right angles to the cutting edge 3 is adapted to be minus. Since the rake angle of the cutting edge 3 is minus when a hole is drilled, synthetic resin is strongly pressed by the rake face 4, reinforcing fibers are cut off as if they were cut with scissors, cutting operation is advanced from the inner periphery of the hole toward its center and thus no burrs or peeling are produced.

Description

[Detailed Description of the Invention] "Industry" 2 Field of Application] This bill is made of carbon fiber, Kevlar fiber, etc.
The present invention relates to a hole-drilling tool suitable for use in the hole-drilling process of a fiber reinforced composite material.

[Conventional technology and its problems 1 In recent years, the development of fiber-reinforced T9 composite material 1 [21] has been rapidly progressing.
This is the case when machining materials made of FRI) etc. For example, C F R P is
The tensile strength of the synthetic resin is increased by interposing woven carbon fibers within the synthetic resin. However, CFRP
Machining was extremely difficult due to the presence of reinforcing fibers inside. In particular, when drilling holes with a drill, reinforcing fibers remained on the entry and exit sides of the drill, making it nearly impossible to drill the holes. For this reason, there has been a strong demand for a drilling tool suitable for drilling holes in fiber-reinforced 'F9 composite materials.

[Object of the Invention] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a drilling tool that can perform drilling without generating reinforcing fiber curls.

[Means for Solving the Problems] The drilling tool of the present invention is configured such that the cutting edge goes from the base end to the distal end as it goes from the inner circumferential side to the outer circumferential side,
And the rake angle of the cutting edge in the cross section perpendicular to the cutting edge is 0.
It is set to 0 or less.

[Function] In the drilling tool with the above configuration, the rake angle of the cutting edge in the cross section perpendicular to the cutting edge is set to 0° or less, so the synthetic resin is strongly pressed by the rake face continuous with the cutting edge, and is strengthened. The fibers are also strongly pressed against the synthetic resin side. As a result, the reinforcing fibers are cut off as if they were cut with scissors, and no reinforcing fibers remain on the surface processed by the cutting blade. Moreover, since the cutting edge is configured to move from the base end to the distal end as it goes from the inner circumference to the outer circumference, cutting progresses from the inner circumference of the hole to the center, preventing peeling due to cutting thrust. occurrence is prevented.

[Embodiment] Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 6. FIG. 1 is a side view showing a drilling tool according to an embodiment. In FIG. 1, reference numeral 1 indicates a tool body. The tool body 1 is made of, for example, cemented carbide or cermet, and is designed to be rotated clockwise, that is, rightward, when viewed from the base end. Tool body 1
A flat portion 2 is formed on one side of the tip. Flat part 2
is for discharging chips, and the distance H from the axis O is 5% to 25% of the diameter D of the tool body l. Further, the outer peripheral portion 1a of the tool body 1 is formed into a cylindrical smooth curved surface. This outer peripheral portion 1a is provided with a back taper, and this back taper is set to Q, 4 mm to 2 mm per 100 mm of length in the axis O direction. A cutting edge 3 is formed on the tip ridgeline of the tool body 1 and extends through the axis O from one side of the tool body 1 to the other side.

The cutting blade 3 has a straight line, and the axis 0 extends from the base end to the distal end as it goes from the inner circumference side to the outer circumference side.
It is tilted at an angle θ with respect to. Incidentally, the inclination angle θ of the cutting blade 3 is set to lO0 to 75°, preferably << is 15
The angle is set between 65° and 65°, preferably between 20° and 55°. There is a rake surface 4 between this cutting edge 3 and the tip edge of the recess 2.
is formed. The rake face 4 is formed as a flat surface inclined at an angle α in the counterclockwise direction with respect to a plane including the cutting blade 3 and the axis 0 when viewed from the direction along the cutting blade 3,
As a result, the rake angle α of the cutting blade 3 in the cross section orthogonal to the cutting blade 3 is set to −α. Here, the angle α is 15
The angle is set between 75° and 75°, preferably between 20° and 600°, more preferably between 30° and 50°. The lower limit of this numerical limitation is a range that can further improve the cutting performance of reinforcing fibers, and the upper limit is a range that can further reduce cutting resistance. However, the angle α may be zero. Incidentally, since the part of the cutting blade 3 that is involved in the cutting process is the part below the axis line ○ in FIG. 1, the cutting blade may be formed only in that part.

In addition, on the opposite side of the groove face 4 across the cutting edge 3, there is a flank face 5.
is formed. The relief angle β in the cross section of the relief surface 5 perpendicular to the cutting edge 3 is set to 5° to 75°. The lower limit of this numerical limitation is a range that prevents second hit, and the upper limit is a range that can maintain the rigidity of the cutting edge.

Next, with the drilling tool having the above configuration, for example, CF R
The operation when performing the hole drilling process of P will be explained with reference to FIG. FIG. 8 shows a cross section perpendicular to the cutting edge 3 during drilling, and in the figure, reference numeral A indicates a workpiece. Countless reinforcing fibers F are woven into the inside of the work material A. In the above drilling tool, since the rake angle of the cutting edge 3 is negative, the synthetic resin M is strongly pressed by the rake face 4, and the reinforcing fibers F facing the cutting edge 3 are also
Forced to the side. As a result, the reinforcing fibers F are cut off as if they were cut with scissors, and no reinforcing fibers F remain on the surface processed by the cutting blade 3. Moreover,
Since the cutting edge 3 is inclined with respect to the axis, the cutting process L progresses from the inner circumference of the hole toward the center, and the occurrence of peeling due to cutting thrust is prevented. Therefore, it is possible to prevent the occurrence of burrs I7 due to the reinforcing fibers F, and it is possible to perform hole drilling in the fiber reinforced composite material as smoothly as drilling in metal materials.

Note that the above-mentioned drilling tool is configured so that the cutting blade 3 passes through the axis O, but as shown in Figure 5 (not shown) and Figure 7, the cutting blade 3 is configured to pass through the axis O and a straight line perpendicular to the axis O. It may also be arranged in a so-called below-center position, in which it is shifted backward in the rotational direction by a length Q in parallel.

With this configuration, the radial rake angle γ of the cutting edge 3 can be made positive, and cutting resistance can be reduced.

By the way, when the cutting blade 3 is disposed below the center as described above, a problem arises in that the center portion having the radius of the below center length ρ is not cut, leaving uncut parts. However, as shown in FIG. 7, by making the thickness of the work material 1" or less, the uncut material can be allowed to fall from the machined hole.

Next, FIGS. 9 to 13 show other embodiments of the present invention, in which the present invention is applied to a so-called 1-revening tool.

In the figure, reference numeral 10 denotes a main body 10, and the tool main body 10 has a cylindrical shape, and chip dents 1 and 11 are formed on the outer periphery of the tool main body 10. A cutting edge 12 similar to that of the drilling tool shown in FIG.
A four part l3 is formed between 2 and 12. Part 4 l3
The core of the workpiece is produced without performing any cutting action, and the bottom thereof is formed into a V-shaped cross section.

In this case, the cutting efficiency is improved by providing a pair of cutting edges 12, and the cutting efficiency is increased by 1-2. Since the thrust forces of the cutting resistance of the two cutting edges l2 balance each other, vibration of the tool body IO can be prevented.Also, since the core generated in the center of the machined hole is crushed by the bottom of the recess 13, , capable of deep hole machining.

Next, FIGS. 12 and 13 show a modification of the trebanning tool No. 14, in which the tool body 1 is attached to the bottom of the fourth part l3.
A hole 14 that communicates with the base end of the hole 14 and has a larger diameter than the inner diameter of the recess 13.
The core and chips can be discharged by vacuum suction from the hole 14, or the chips can be discharged from the chip pocket 1l by injecting compressed air from the hole 14.

In this trebanning tool, the cutting edge l2 may be formed symmetrically with respect to the axis 0, or may be asymmetrical. Further, the length of one cutting edge 12 may be longer than the other. Furthermore, the cutting edge 12 may be arranged below the core.

Incidentally, in each of the above-mentioned embodiments, the cutting edge is configured in a straight line, but it may be curved as long as it goes from the base end to the distal end as it goes from the inner circumferential side to the outer circumferential side. Further, although the tool body and the cutting blade are integrally made of cemented carbide, only the cutting blade may be made of cemented carbide or an ultra-high hardness sintered body. Furthermore, a large number of cutting edges may be provided.

[Effects of the Invention] As described in Explanation 1, in the drilling tool of the present invention, the cutting edge is configured to move from the inner circumferential side to the outer circumferential side and from the base side to the tip side, Well, since the rake angle of the cutting edge divided into the cross sections perpendicular to the cutting edge is 00 to negative]5,
During drilling, the synthetic resin is strongly pressed by the scoop along the cutting blade, and the reinforcing fibers facing the cutting blade are also strongly pressed against the synthetic resin. As a result, the reinforcing fibers are cut off as if they were being cut with scissors, and no reinforcing fibers remain on the surface processed by the cutting knife. Moreover, since the cutting edge is configured to move from the base end to the distal end as it goes from the inner circumference to the outer circumference, the cutting progresses from the inner circumference of the hole to the center, preventing peeling due to cutting thrust. occurrence is prevented. Therefore, it is possible to prevent the reinforcing fibers from peeling off or peeling, and it is possible to smoothly drill holes in fiber-reinforced composite materials in the same way as holes in metal materials.

[Brief explanation of drawings]

1 to 7 are views showing one embodiment of the present invention, in which FIG. 1 is a side view showing a drilling tool, FIG. is the ■ direction arrow view in Figure 1, and the 4th
The figure is a view of the drilling tool in the IV direction in FIG. 1, FIGS. 5 to 7 show modifications of the drilling tool shown in FIG. 1, and FIG. Fig. 6 is a view of the tip in the axial direction, Fig. 7 is a side sectional view showing a state in which drilling is being performed, and Fig. 8 is a cutting blade showing a state in which drilling is being performed in FRP. Orthogonal cross-sectional views, Figures 9 to 1
3 shows another embodiment of the present invention, FIG. 9 is a side view of the trebanning tool, FIG. 10 is a view taken in the X direction of FIG. 9, and FIG. 11 is a view taken in the ■ direction of FIG. 9. 12 is a side view showing a modification of the trepanning tool shown in FIG. 9;
FIG. 13 is a top view in the axial direction. 3, l2...cutting edge, I3...concavity, α...rake angle, O...axis line.

Claims (3)

[Claims] (1) In a drilling tool in which a cutting edge extending from the inner circumferential side to the outer circumferential side is provided on the tip ridgeline of the tool body that is rotated around the axis, the cutting edge extends from the inner circumferential side to the outer circumferential side. The rake angle of the cutting edge in the cross section perpendicular to the cutting edge is 0°.
A drilling tool characterized by the following: (2) A patent characterized in that a pair of the cutting blades are provided with the axis line in between, and a recessed part is formed at the tip portion along the axis line of the tool body to generate a core of the workpiece without performing a cutting action. A drilling tool according to claim 1. (3) At least the outer periphery of the tip of the tool body is formed into a cylindrical curved surface, and the back taper of the outer periphery is 0.4/10.
The drilling tool according to claim 1 or 2, characterized in that the diameter is 0 to 2/100.