JPH03142199A - Drilling method and drilling tool - Google Patents

Abstract

PURPOSE:To drill a hole having a continuous uniform inner peripheral face by forming a drilling part on the tip side and forming a file part of a larger diameter than that of the drilling part on the rear end side thereof. CONSTITUTION:A prepared hole 14 is formed in a foaming mold 12. A desired hole 18 is then formed by inserting a file part 8 into the prepared hole 14 while rotating a tool on whose outer peripheral face a file part 8 with an outer diameter larger than the inner diameter of this prepared hole 14 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a drilling method for making circular holes in a foamed molded product and a drilling tool suitable for use in the processing method.

[Prior art] Conventionally, when making holes in a molded product made of foamed resin,
For example, holes were made using a processing tool such as a drill or a hole saw, and no further treatment was performed after that.

[Problem to be solved by the invention] However, foam molded products have cavities inside them.

For this reason, if a hole is simply drilled with a processing tool, a cavity will be exposed on the inner circumferential surface of the drilled hole, which not only spoils the aesthetics but also reduces the value of the molded product as a product. There was a problem.

This invention was made to solve the above problem.
Provides a drilling method that can prevent cavities from being exposed on the inner peripheral surface of the hole when drilling holes in a foam molded product, and a drilling tool suitable for carrying out the method. The purpose is to

[Means for Solving the Problems] In order to achieve the above object, the drilling method of the present invention includes forming a pilot hole in a foam molded product, and then using a file having an outer diameter larger than the inner diameter of the pilot hole. The file part is inserted into the prepared hole while rotating a tool having a part formed on the outer peripheral surface.

Further, the drilling tool of the present invention is characterized in that a drilling part for making a hole is formed on the tip side, and a file part having a larger diameter than the drilling part is formed on the rear end side. It is.

[Operation] In the drilling method of the present invention, a pilot hole is first formed in the foam molded product. Of course, a cavity is exposed on the inner peripheral surface of this pilot hole. Next, insert the file part into the prepared hole while rotating it. Then, the inner circumferential surface of the prepared hole is ground down by the file part by the difference between the inner diameter of the prepared hole and the outer diameter of the file part, and fine resin powder is generated. This fine powder is melted by the frictional heat generated as the inner peripheral surface of the pilot hole rubs against the file portion, and is filled into the cavity. As a result,
The void is filled. Therefore, the inner circumferential surface of the resulting hole becomes a continuous surface entirely without exposing the cavity.

Further, the drilling tool of the present invention is used while being rotated and fed toward its tip. When used in this manner, the hole-piercing section on the tip side makes a pilot hole in the foamed molded product. Thereafter, the file portion on the rear end side performs finishing processing to obtain a hole having an inner circumferential surface without exposing the cavity.

[Examples] Examples of the present invention will be described below with reference to the accompanying drawings.

First, let us explain about the hole-cutting tool used in carrying out the hole-cutting method of this invention. Figures 2 and 2 show one embodiment of the hole-cutting tool of this invention. It is. The drilling tool of this embodiment is an improved hollow mill, and has a cylindrical body 4 coaxially fixed to a shaft called a shank 2. This cylindrical main body 4 is used to machine a pilot hole, and a sawtooth (hole hole portion) 6 is formed on its tip surface. Further, a file portion 8 consisting of a flattened funnel and throat is formed at the rear end portion of the outer peripheral surface of the cylindrical main body 4. In this case, the file part 8
The diameter is O3~0.5mm from the outer diameter of the cylindrical main body 4.
It is made large, with a width of 5 to 7 mm. However, these values may be changed as appropriate depending on the foaming rate, thickness, etc. of the foamed molded product to be punched.

Further, a drill 10 is coaxially fixed to the center of the cylindrical main body 4. The tip of this drill 10 has a cylindrical body 4
It protrudes in the distal direction from the tip of the. The inner circumferential surface of the cylindrical main body 4 and the outer circumferential surface of the drill 10 fit together without any gap.

Next, an example of the drilling method according to the present invention will be explained by explaining the case where a hole is made in a foamed molded product with a processing tool.

To make a hole in the molded product 12 made of foamed resin, the tool is rotated about its axis and fed toward the tip. Then, first, the tip of the drill 10 begins cutting the center of the hole to be drilled, and positioning is thereby performed. The drill 10 continues drilling, and eventually the saw teeth 6 of the cylindrical body 4 come into contact with the product 12 and start drilling. A pilot hole 14 shown in FIG. 3 is machined by the saw teeth 6. Of course, the cavity 16 is exposed on the inner peripheral surface of the prepared hole 14.

Note that this drilling tool does not have a gap between the inner circumferential surface of the cylindrical body 4 and the outer circumferential surface of the drill 10 as in conventional hollow mills. Therefore, the cylindrical body 4 and the drill 1
0, there is no part of the workpiece shaped like a donut remaining between the two, and the effort of removing it can be saved.

When the cylindrical body 4 is further advanced after the pilot hole has been machined by the saw teeth 6 of the cylindrical body 4, the file portion 8 on the outer periphery scrapes the inner circumferential surface of the pilot hole 14. Due to this abrasion, the pilot hole 1
The inner circumferential surface of the pilot hole 14 is ground down by the difference in diameter between the file portion 4 and the file portion 8, and fine powder is generated. This fine powder is melted by the frictional heat generated by the friction between the file portion 8 and the inner circumferential surface of the prepared hole 14 . Then, as the file portion 8 rotates, the cavity 16 is filled. As a result, the cavity 16 is filled, and the desired hole 8 having a continuous and uniform inner peripheral surface as shown in FIG. 4 is obtained.

The hole drilling method and processing tool of the present invention are not limited to the above-described embodiments, and may be modified as appropriate without departing from the spirit thereof.

For example, in the above processing method, a desired hole 1 is formed using a tool having both sawtooth (hole processing part) 6 for forming the pilot hole 14 and file part 8 for eliminating the cavity 16.
8 is formed, but when drilling the - hole, first drill the pilot hole 14 with a tool, and then drill the pilot hole 14 with a tool that has a file part separately from the tool. good.

Further, other embodiments of the machining tool are as follows.

FIG. 5 shows a second embodiment of the invention. The file portion 8 in the first embodiment was a flat knurl, but in this embodiment it is a cross knurl. In addition, the file part 8
is formed not at the rear end of the outer periphery of the cylindrical main body 4 but at the middle part thereof. Further, a ring-shaped protrusion 20 is formed at the rear end of the outer periphery, and the perforation prevents the entire cylindrical body 4 from later slipping out from the hole 18 in the feeding direction.

A third embodiment of the invention is shown in FIG. In the two embodiments described above, there was no gap between the drill 10 and the inner surface of the cylindrical body 4, but in this embodiment, a gap 22 exists. By providing this gap 22, drilling can be performed with a small rotational force.

A fourth embodiment of the invention is shown in FIG. In this embodiment, a coil spring 24 is provided around the drill 10, and during drilling, the tip of the coil spring 24 hits the edge of the hole and the coil spring 24 contracts in the axial direction. Therefore, when the machining of the prepared hole 14 by the saw teeth 6 is completed, the doughnut-shaped uncut portion existing between the inner circumferential surface of the cylindrical body 4 and the outer circumferential surface of the drill 10 is removed by the repulsive force of the contracted coil spring 24. It is pulled out from the tip of 10. Further, the file portion 8 is formed over a wide area, so that even when the length of the hole is long, the cavity can be sufficiently filled.

Although the drill 10 was provided in the above embodiment, it is also possible to not provide the drill as in the fifth embodiment shown in FIG. This is because if the inner diameter of the hole is relatively small or if the foamed molded product into which the hole is to be drilled is soft, it is possible to correctly drill the hole at the desired position without positioning with a drill.

A sixth embodiment of this invention is shown in FIG. Although the saw teeth 6 in the above embodiment were fine, the saw teeth 6 in this embodiment are large. Drilling holes at a high speed is advantageous when processing foamed synthetic resin products with rough materials.

[Effects of the Invention] As explained above, according to the processing method of drilling a hole according to the present invention, a file portion having a diameter larger than the inner diameter of the prepared hole is inserted into the prepared hole while rotating, so that a cavity is formed on the inner peripheral surface. It is possible to make a hole with a continuous and uniform inner circumferential surface without exposing any part of the material.

In addition, according to the processing tool of the present invention, it is possible to continuously perform the formation of a pilot hole and the finishing hole machining to eliminate a cavity exposed on the inner circumferential surface of the pilot hole, thereby improving machining efficiency. can be improved.

[Brief explanation of the drawing]

1 and 2 show a first embodiment of the hole drilling tool according to the present invention, FIG. 1 is a partially omitted front view showing the hole drilling situation, and FIG. 2 is a partially omitted front view. An abbreviated vertical cross-sectional view, FIG. 3 is a perspective view showing the prepared hole made by the saw blade of the processing tool, and FIG. 4 is a perspective view showing the hole shown in FIGS. 1 and 2. The light is a perspective view showing a hole machined by the file part of the processing tool, and each of FIGS. 5 to 9 shows an embodiment of the processing tool according to the invention. The figure is a front view, and FIGS. 6, 7, and 8 are semi-longitudinal views. 4... Cylindrical body, 6... Sawtooth (holes are part), 8...
File part, 12... Foamed molded product, 14... Prepared hole, 1
6. Cavity, 18. Hole (after the file is inserted).

Claims (2)

[Claims] (1) After forming a pilot hole in the foam molded product, insert the file portion into the pilot hole while rotating a tool, which has a file portion formed on the outer peripheral surface with an outer diameter larger than the inner diameter of the pilot hole. Characteristic drilling method. (2) A drilling tool, characterized in that a drilling portion is formed on the leading end side, and a file portion having a larger diameter than the drilling portion is formed on the rear end side.