JPH0747243B2 - Drills for drilling composite materials - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a drill for piercing a composite material, and more particularly to a composite material suitable for piercing a composite material of a fiber resin hardening material and a metal material which are superposed on each other. A drill for drilling a material.

[Prior Art] A fiber-resin cured composite material in which fibers are laminated, impregnated with a resin, and cured is widely used as an industrial material, particularly as a material for aircraft. In the assembly process of aircraft production, in order to combine a composite material part and a metal part such as aluminum, a work of drilling a hole having the same diameter through both parts and riveting is often performed. However, as shown in FIG. 11, when the composite material component 1 and the aluminum component 2 are piled up and punched with a metal drill 3 from the composite material 1 side, the composite material has a weak adhesive force between layers, and the drill material is drilled. The fibers of the composite material are lifted by the twist angle α and the rake angle of the drill at the inlet side (starting side of drilling), and burrs, cracks, delamination, or delamination occurs. On the contrary, as shown in FIG. 12, when the aluminum component 2 is drilled from the side, the drill thrust force causes the fibers to be separated at the drill outlet side, causing delamination and the like. Such delamination or the like significantly shortens the life of the composite material. To prevent this,
Conventionally, a backup material is tightened on the exposed surface of the composite material and then perforated. However, this backup material tightening work is time-consuming and it may not be possible to mount the backup member inside when the processed product is a box-shaped product.

Various drills have been developed for composite materials that prevent delamination and the like. For example, Japanese Utility Model Publication No. 59-33546 and Japanese Patent Application Laid-Open No. 58-149114 disclose a drill for composite material particularly suitable for an aramid fiber-based composite material. However, these cannot be used for the carbon-based composite metal because the wear and damage of the cutting edge are remarkable. Therefore, as a drill that demonstrates excellent performance for carbon-based composite materials,
The dagger drill disclosed in U.S. Pat. No. 4,093,395 was developed. In this dagger drill, as shown in FIGS. 13 to 15, rake planes 5 are formed on both sides of the drill body 4. The pair of rake planes 5 are tapered so as to converge toward the tips 6, and the tips thereof are ground to form front flanks 5A, thereby forming a cutting edge 7 having a tip angle A of about 35 °. Has been done. The cutting edge 7 has a rake angle B of about 5 ° and a clearance angle C of about 55 °. As described above, since the rake angle B is negative and the clearance angle C is large, the tip cutting edge 7 can prevent delamination and the like and can prolong the life of the cutting edge. Furthermore, the pair of tapered flat surfaces 5 facilitates the discharge of chips.

[Problems to be Solved by the Invention] However, even when this dagger drill is used for metal, it is significantly worn or damaged, and cannot be used for punching composite parts and metal parts in a superposed state. .

Therefore, an object of the present invention is to provide a composite material drilling hole having excellent durability, which is capable of drilling a composite material and a metal in a superposed state without using a backup material without causing delamination or the like. is there.

[Means for Solving the Problems] In order to achieve this object, the present invention provides a composite material drill having a spiral groove for discharging chips from the drill tip to the vicinity of the shank. The tip part is formed continuously with a primary cutting edge having a tip shape of a metal drill having a tip angle of about 90 °, and a flat secondary cutting edge having an angle angle of about 20 ° to 30 °. Configured, the maximum diameter d of the primary cutting edge and the maximum diameter D of the secondary cutting edge
The ratio d / D of the secondary cutting edge is set within the range of about 3/5 to 2/3, the clearance angle of the secondary cutting edge is set within the range of about 20 ° to 25 °, and the twist angle of the twist groove is set. Is characterized in that it is set within the range of about 20 ° to 30 °.

Further, a tertiary cutting edge that is inclined through a cutting edge portion that is substantially parallel to the axis and that is continuous with the secondary cutting edge is formed in a step shape,
It is preferable that the tertiary cutting edge has substantially the same tip angle as the secondary cutting edge.

[Operation] When the composite material and metal in a superposed state are perforated by the drill having such a configuration, the primary cutting edge of the drill tip first makes a relatively small diameter primary hole and then the secondary cutting edge. Forms a secondary hole by punching the outer peripheral portion of the primary hole punched by the above-mentioned leading edge. Since the primary cutting edge of the drill tip has the shape of the metal drill tip, there is no problem of wear or damage, but delamination occurs around the primary hole of the composite material. However, this delamination around the primary hole is removed when the outer peripheral portion of the primary hole is drilled by the secondary cutting blade. Further, since the secondary cutting edge is a flat cutting edge, it is susceptible to wear and damage due to metal perforation,
By setting the cutting amount of the secondary cutting edge to be sufficiently smaller than the cutting amount of the primary cutting edge, the above wear and damage can be sufficiently reduced to the extent that there is substantially no problem. First Example of Drill for Drilling Composite Material by
This will be described with reference to FIGS.

In FIG. 1, a drill 10 for piercing a composite material is provided with a spiral groove 13 for discharging chips on the outer peripheral surface from a tip portion 11 to the vicinity of a shank portion 12. The tip portion 11 has a primary cutting edge 11A.
And a secondary cutting edge 11B formed continuously from this. This primary cutting edge 11A has the same or almost the same shape as the tip of the metal drill, and the shape of the secondary cutting edge 11B is the same or almost the same as the flat cutting edge known as a dagger drill. is there.

When the composite material and the metal in a superposed state are perforated by the drill having such a configuration, the primary cutting edge 11A of the drill tip 11 first pierces a relatively small diameter primary hole, and then the secondary cutting edge 11B is primary. The outer peripheral portion of the primary hole punched by the cutting blade 11A is punched to form a secondary hole. Since the primary cutting edge 11A has the shape of the tip of the metal drill, there is no problem of wear or damage, but it causes delamination at the outer periphery of the primary hole of the composite material. However, the delamination of this primary hole outer peripheral portion is removed when the secondary cutting edge 11B pierces the primary hole peripheral portion, and this secondary cutting edge 11B is a flat cutting edge and causes delamination. As a result, there is no delamination in the primary holes. Also, the secondary cutting edge 11
B is susceptible to wear and damage during perforation of metal, but the wear and damage are substantially reduced by setting the cutting amount of the secondary cutting edge 11B to be sufficiently smaller than the cutting amount of the primary cutting edge 11A. It can be made sufficiently small that there is no problem.

The helix angle α of the spiral groove 13 is optimally about 20 ° to 30 °, and the tip angle β of the primary cutting edge 11A is determined by the type of metal to be drilled, and generally about 90 ° is optimal. The optimum tip angle γ of the secondary cutting edge 11B is about 20 ° to 30 °. In addition, as shown in FIGS. 2 (a) and (b), the primary cutting edge
The ratio d / D between the maximum diameter d of 11A and the maximum diameter D of the secondary cutting edge 11B (this ratio is called the angle position ratio) is optimally about 3/5 to 2/3.

Further, as shown in FIGS. 3 and 4, the clearance angle δ is about
20 ° to 25 ° is optimal. A specific example of these various values is shown below. α = 20 °, β = 90 °, γ = 30 °, δ = 20 °.

In FIG. 5, the horizontal axis represents the twist angle α and the tip angle β of the drill, and the vertical axis represents the delamination factor represented by delamination width / hole diameter. As is clear from this graph, twist angle α = 20 ° to 30 °, tip angle β = 90 °
The probability of occurrence of delamination is lowest when.

FIG. 6 shows the relationship between the angle angle γ of the secondary cutting edge 11B and the delamination occurrence rate, and shows that the range of about 20 ° to 30 ° is optimal. FIG. 7 shows the relationship between the angle position ratio d / D and the delamination occurrence rate, and the optimum range is about 3/5 to 2/3.

Furthermore, FIG. 8 shows the relationship between the clearance angle δ and the delamination occurrence rate, and the optimum range is 20 ° to 25 °.

FIG. 9 shows a second embodiment of the present invention suitable for a drill having a diameter larger than that of FIG. 1 (about 10 to 20 mm), and the drill tip 11 is completely different from that of FIG. Similarly, it is composed of a primary cutting blade 11A having a metal drill tip shape and a secondary cutting blade 11B having a dagger drill tip shape. This secondary cutting edge 1
Behind 1B, a tertiary cutting edge 15 having the same shape as the secondary cutting edge 11B is formed in a step shape through a cutting edge portion 14 substantially parallel to the axis. The tertiary cutting edge 15 has angles γ and δ of about 20 ° to 30 ° and about 20 ° to 25 ° as shown in FIGS.
It is preferable to set to °. With such a configuration, the primary cutting edge 11A and the secondary cutting edge 11B of the tip portion 11 first pierce the pilot hole, and the tertiary cutting edge 15 pierces the outer periphery of the pilot hole. In this way, the tertiary cutting edge 15 only punches the outer circumference of the pilot hole, so that the drilling load is small and even when cutting metal, there is very little wear or damage. Also, the tertiary cutting edge 15
Is guided by the engagement between the tip portion 11 and the pilot hole, so that vibration is suppressed and high-precision drilling can be performed.

[Effects of the Invention] As is clear from the above description, according to the present invention, the drill tip portion is a primary cutting blade having the shape of the tip portion of a metal drill, and a flat secondary cutting blade continuous to this leading edge. Since it is composed of the blade, the composite material and the metal in the superposed state can be punched with high precision without the occurrence of denomination or the like without using a backup material, and further, the durability can be improved.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a drill for drilling dissimilar materials according to the present invention, and FIGS. 2 (a) and 2 (b) are side views and front views in which a tip portion of the drill is enlarged, and FIG. The figure shows an enlarged front view of the tip of the drill, and Fig. 4 is the IV of Fig. 2 (b).
-A cross-sectional view taken along the line IV, Fig. 5 is a diagram showing the relationship between the twist angle and the tip angle of the drill and the delamination factor, and Fig. 6 is a view showing the relationship between the angle angle γ and the delamination occurrence rate. Fig. 7 is a diagram showing the relationship between the angle position ratio d / D and the delamination occurrence rate, and Fig. 8 is a line showing the relationship between the clearance angle δ of the cutting edge and the delamination occurrence rate. Fig. 9 is a front view showing a drill for drilling according to another embodiment of the present invention, Fig. 10 (a) is an enlarged front view showing a second cutting edge portion, and Fig. 10 (b). Is D- in Fig. 10 (a)
Sectional views taken along the line D, FIG. 11 and FIG. 12 are explanatory views showing a state when the composite material is drilled with a metal drill, respectively.
The figure is a perspective view showing a conventional dagger drill, 14th and 15th
The drawings are a side view and a plan view taken along the line EE and the line FF of FIG. 13, respectively. 10 …… Composite drilling drill, 11 …… Tip, 11A …… Primary cutting edge, 11B …… Secondary cutting edge, 12 …… Shank part, 13 ……
Twist groove.

Claims (2)

[Claims] 1. A composite material drilling drill having a spiral groove for discharging chips from the drill tip to the vicinity of a shank, wherein the drill tip has a tip shape of a metal drill having a tip angle of 90 °. And a primary cutting edge continuously formed on the primary cutting edge, which is composed of a flat secondary cutting edge having an angle of 20 ° to 30 °, and the maximum diameter d of the primary cutting edge and the above. The ratio d / D to the maximum diameter D of the secondary cutting edge is 3/5
Set to within 2/3, the clearance angle of the above secondary cutting edge is 20
A drill for composite material drilling, characterized in that it is set within a range of ° to 25 °, and the twist angle of the above-mentioned twist groove is set within a range of 20 ° to 30 °. 2. A tertiary cutting edge which is continuous with the secondary cutting edge and which is inclined through a cutting edge portion substantially parallel to the axis is formed in a stepped shape, and the tertiary cutting edge is almost the same as the secondary cutting edge. The drill for piercing a composite material according to claim 1, which has the same tip angle.