JPH03264205A - Boring tool of internal face resin lining material - Google Patents

Abstract

PURPOSE:To cut a coating film and yet to discharge a cutting piece well, by taking the tip angle of a tool at 70 deg.min. 90 deg.max, in the case of punching the material of which the internal face a resin lining is executed from the external face and taking the angle of torsion at 10 deg.min. 30 deg.max. CONSTITUTION:The tip angle of a drill 5 is taken at 70 deg.min. 90 deg.max. and the angle of torsion namely rake angle at 10 deg.min. 30 deg.max. When the drill 5 cuts a cast iron pipe 2 and its tip 6 reaches a coating film 4, the film 4 is broken through earlier by the acute angled tip 6, the cutting width of the coating film becomes narrow and the shearing force onto the coating film becomes smaller and so the cutting can be performed by preventing the rupture thereof. Also the discharging of a cutting piece is performed smoothly by forming a rake angle and yet a continuous cutting becomes possible and the drop of the cutting piece into the pipe can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an inner resin material for drilling from the outer surface of a cast iron pipe, steel pipe, or cast iron plate or steel plate whose inner surface is lined with resin to form a laminated structure. This invention relates to a drilling tool for lining materials.

Conventional technology For example, when drilling a hole in a pipe body, the diameter of the hole is 30 mm.
- In the following cases, a drill is generally used as a drilling tool. In Japan, the point angle of the drill is
As shown in the figure, the angle is defined as 118 degrees. Furthermore, as shown in FIG. 3, drills for drilling into tubular bodies are often used with a cutting edge having a rake angle, that is, a helix angle of 0 degrees.

Problems to be Solved by the Invention When using the conventional drill as described above to drill a hole from the outside into a tube whose inner surface is coated with a hard resin lining such as powder coating, there are the following problems.

That is, when a drill with a tip angle of 118 degrees as shown in FIG. Even if the coating [14] is deformed and not cut even if the
As shown in the figure, since the coating I14 is pierced from the back side, there is a problem that it is likely to be chipped or peeled up around the perforation.

Further, when a drill with a rake angle of 0 degrees as shown in FIG. 3 is used, there is a problem that the cutting pieces are not discharged and fall into the pipe.

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems and provide a drilling tool which is a drill that can cut a coating film and also discharge cutting pieces well.

Means for Solving the Problems In order to achieve the above objects, the drilling tool of the present invention comprises a drill having a tip angle of 70 degrees or more and 90 degrees or less, and a helix angle of 10 degrees or more and 30 degrees or less. This is what I did.

Effect With this configuration, the tip angle becomes acute, so
Since the coating film of the W greasy coating is pierced at an early stage and reaches a cutting state, chipping and tearing of the coating film are prevented. This is because by making the tip angle acute, the cutting width of the coating film becomes narrower, and the shearing force applied to the coating film becomes smaller, so that cutting can be performed while preventing the coating film from breaking.

The tip angle needs to be 70 degrees or more; if it is smaller than that, the load torque of the prime mover for rotating the drill will increase rapidly, making the prime mover more likely to malfunction or break the drill. It is also necessary that the angle be 90 degrees or less; if it exceeds that angle, as mentioned above, the resin coating such as epoxy will deform and adapt to the shape of the cutting edge, so the coating will not be cut and will eventually break through. become.

Further, according to the above configuration, the helix angle, that is, the rake angle is reduced to 1
By setting the angle to 0 degrees or more and 30 degrees or less, the cutting pieces can be smoothly discharged and continuous cutting can be performed.

The helix angle needs to be 10 degrees or more; if it is smaller than that, it will be difficult to cut and the coating will be easily broken, and it needs to be less than 30 degrees; if it exceeds it, the cut pieces will become spiral-shaped. It tends to form a continuous shape, making it difficult to discharge from the drilling machine during drilling. Furthermore, the larger the helix angle, the better the sharpness of the drill, but on the other hand, the strength of the cutting edge decreases.

Embodiment FIG. 1 shows a drill 5 which is a drilling tool according to an embodiment of the present invention.
This figure shows how the drilling work is performed. As in the case of Figure 4,
A case is shown in which a hole is drilled into a laminated pipe in which a coating JI4 of Ill fat lining is formed on the inner surface of a cast iron pipe 1.

As illustrated, the tip angle θ of the drill 5 is formed to be 70 degrees or more and 90 degrees or less. Also drill 5
has a helix angle of 10 degrees or more and a rake angle of 3
It is formed so that the angle is about 0 degrees or less.

When drilling is performed with such a drill 5, the drill 5 cuts the cast iron pipe 2 and cuts the tip 6 of the cast iron pipe 2, as shown in FIG. 1(a).
When it reaches the coating film 4, the sharpened tip 6 causes coating 1! I4 will be breached early. For this reason, the coating film 4 is in a state where it is cut, and the occurrence of chipping and blistering around the perforation is prevented. Further, by forming a predetermined rake angle, the cutting pieces can be smoothly discharged and continuous cutting can be performed. This prevents the cutting pieces from falling into the pipe. FIG. 1(b) shows the state immediately before completion of the drilling operation.

Table 1 shows the drilling results when the tip angle and rake angle were variously changed with a drill diameter of 23 - and a drill rotation speed of 12 Orpm.

Table 1 As mentioned above, the helix angle must be 10 degrees or more and 3 degrees or less, but if the peripheral speed of the drill is 30 to 50 m/s
In the case of in, 10 to 20 degrees is suitable, and 10 to 30 degrees
In the case of m/sin, 20 to 30 degrees is suitable.

Effects of the Invention As described above, according to the present invention, it is possible to break through the coating film of the resin lining at an early stage and cut it, and it is also possible to smoothly discharge the cut pieces. It is possible to prevent the paint film from being chipped and the occurrence of scratches around the parts, and also to prevent the cutting pieces from falling.

[Brief Description of the Drawings] Fig. 1 is a sectional view showing a drilling operation using a drilling tool according to an embodiment of the present invention, Figs. 2 and 3 are three side views showing a conventional drilling tool, and Fig. 4 The figure is a sectional view showing a drilling operation using a conventional drilling tool. 2... Cast iron pipe, 4... Paint film, 5... Drill (perforating tool), 6... Tip, θ... Tip angle.

Claims (1)

[Claims] 1. A tool for drilling from the outside of a material whose inner surface is lined with resin, with a tip angle of 70 degrees or more and a diameter of 9
0 degrees or less, and the twist angle is 10 degrees or more and 3
A drilling tool for an inner resin lining material, characterized in that it is composed of a drill with a temperature of 0 degrees or less.