JPH079396A - Rotary drilling tool - Google Patents

Abstract

PURPOSE:To provide a drilling tool for working a blind hole having no burns in rubber or a synthetic resin. CONSTITUTION:A body part 3 connected to the tip of a shank 2 is formed into a cylinder having concentricity with a rotating shaft to form a cutting blade 4 at the tip of the cylinder. The edge of the graded part at the tip of the cylinder is also used as a cutting blade 5. In addition, a cutting blade 6 is provided in the radius direction projected from the inner surface of the cylinder toward the central part of the cylinder. Rotating a tool for feeding application cuts the hole edge with the cutting blades 4, 5. The cutting blade 6 is notched in a spiral shape into a core stayed at the center of the hole. Feeding is terminated at the position reached a predetermined depth to rotate the tool. Thus, the cutting blade 6 cuts off the core to form a blind hole.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary drilling tool used for making blind holes in rubber, synthetic resin, cooking materials and the like.

[0002]

2. Description of the Related Art When a soft material such as rubber is drilled with a drill for metalworking or woodworking, so-called burrs are produced and the hole does not look like a hole. Therefore, when drilling holes with good shape accuracy and dimensional accuracy in this type of material, a method is used in which holes are left in the core with a trepanning system tool that has a cutting edge that revolves around the axis. .

[0003]

A tool for drilling a hole leaving a core cannot be used for drilling a blind hole because the core is not separated from the work unless the cutting edge cuts through the work. The same applies to punching holes with a hollow punch.

Therefore, the present invention provides a trepanning type drilling tool capable of cutting not only a through hole but also a blind hole by cutting off the core during the drilling or by cutting off the core portion at the same time. Is what you are trying to do.

[0005]

According to the present invention, in order to solve the above-mentioned problems, the main body portion connected to the shank is a cylinder concentric with the rotating shaft, the leading edge of this cylinder is a cutting edge, and the cylindrical tip is further provided. A tool configuration is adopted in which the portion is provided with a cutting edge in the radial direction that projects from the inner surface of the cylinder to at least the center of the cylinder.

It is more desirable to provide a step in the axial direction in the middle of the peripheral edge of the cylinder and to make the edge of this step also a cutting edge.

Further, instead of using the cutting edge at the tip edge of the cylinder, a cutting edge extending from the inner diameter surface to the outer diameter surface of the cylinder may be provided at the tip of the cylinder.

[0008]

When the tool is applied to the soft work material and rotated and fed, the cutting edge formed on the tip edge of the cylinder enters the work material and the contour of the hole is cut. At this time, the radial cutting edge at the tip of the cylinder spirally cuts into the core left inside the hole due to the rotation accompanied by the feeding, so that the core remains uncut.

Next, when the tool is cut to a predetermined depth, the feeding is stopped, and the tool is rotated once or more at that position. The aforementioned radial cutting edge extends at least to the center of the tool, so that when the tool makes one revolution in position, it passes through the entire circular surface, which completely separates the root side of the core from the work material. , A clean blind hole with no flash on the work material.

If the cutting edge at the tip of the cylinder is a complete annular cutting edge, the cutting of the hole edge will be scraping by pressing the cutting edge, but there is an axial step at the tip of the cylinder and the blade is also cut at that portion. When attached, the blade makes a circular movement to cut the edge of the hole in a scooping manner, thus increasing the drilling efficiency.

When the work material is a so-called soft material such as a soft rubber, a hard rubber, a soft synthetic resin, a food material containing fruits and vegetables, as described above, the radial cutting edge is the core. When the work material is hard material such as hard resin (for example, Bakelite), it is cut into a spiral shape inside, but the hole edge is cut by the cutting edge of the cylindrical tip edge, and the core of the radial cutting edge is cut. You cannot expect a spiral cut. Therefore, in such a case, a cutting edge extending from the inner diameter surface to the outer diameter surface is provided at the tip of the cylinder, and the periphery of the hole is scooped by this blade, further,
The cutting edge in the radial direction is also scooped out so that the core part left at the center of the hole is gradually scraped off.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows the entire drilling tool. This tool 1 has a cylindrical body portion 3 concentric with the shank axis at the tip of a shank 2.

As shown in FIG. 2, the tip of the main body 3 is formed into a cutting edge 4 by slantingly grinding the inner surface of the cylinder to make it sharp.
Further, a step portion is formed midway in the circumferential direction of the tip of the cylinder, and the edge of this step portion is sharpened in the rotational direction when viewed from the front of the tool to form the cutting edge 5.

Further, a protrusion extending radially from the inner surface of the cylinder is provided at the tip of the main body 3, and the edge of the protrusion in the rotational direction is also a cutting blade 6. The length of the cutting edge 6 is at least the length from the inner surface of the cylinder to the center of the cylinder, that is, ½ or more of the diameter of the cylinder.

As shown in FIG. 4 (a), the cutting edge 6 has a hole which is machined when the cutting edge 6 is perpendicular to the center of the cylinder.
It becomes the form shown in (a). When the cutting edge 6 is tilted in the direction shown in FIG. 4B, the hole shape becomes as shown in FIG. 5B. Conversely, when the cutting blade 6 is tilted in the direction shown in FIG. 4C, the hole shape becomes as shown in FIG. It becomes the form shown in (c). The direction of the cutting edge 6 may be arbitrarily selected from the patterns shown in FIG. 4 depending on the shape of the hole bottom. In any orientation, when the tool is fed, it will be spirally cut into the core, and the core will be cut off at the position where the feeding was stopped.

Reference numeral 7 in FIG. 1 denotes an outlet of the core taken inside the main body 3. If the core taken in is to be removed from the tip side of the main body, the cutting edge 6 becomes an obstacle and the work efficiency deteriorates. Therefore, it is preferable to provide the illustrated discharge port 7.

The illustrated tool is in a state in which a hollow hole punch is modified and bladed. However, the tool of the present invention is entirely made up of a pipe including a shank. You can also do it.

Further, the cutting edge 6 for a soft material
May not have sharp edges. For example, when the cutting edge 6 is formed of a bar material such as a circle or a corner, the bar material forcibly crushes the core portion by the feeding of the tool and enters the inside,
Thread the core at the position where the feed was stopped. A bar material, a plate material, and the like having such a function are also included in the radial cutting edge according to the present invention.

FIG. 6 shows a tool according to the second aspect of the present invention.
As shown in the figure, a plurality of cutting blades 8 extending from the inner diameter surface to the outer diameter surface of the cylinder are provided at the tip of the cylindrical body, preferably at equal pitches in the circumferential direction. There is a radial cutting edge 9 extending to the center of the. This tool is used for drilling holes in a hard resin or the like, and the cutting blade 8 scrapes off the peripheral portion of the hole and the cutting blade 9 scrapes off the core portion little by little.

In the embodiment, the number of cutting edges 6 and 9 is one, but the number is not limited.

[0021]

As described above, the drilling tool of the present invention has a cutting edge for cutting the core left at the tip of the main body (cylinder) and a spiral cutting into the core when the tool is fed,
Alternatively, since it is configured to have a radial cutting edge that cuts off the core at the position where it is forcibly pushed in and stops feeding, or a cutting edge that gradually scoops the core part, it is not possible with conventional trepanning tools. It is possible to process blind holes in rubber, synthetic resin, etc., which can contribute to diversification of processing, cost reduction, and improvement in product design flexibility.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a drilling tool of the present invention.

FIG. 2 is a vertical cross-sectional view taken along line II-II of the above.

FIG. 3 is a cross-sectional view near the tip.

FIG. 4 is a diagram showing the orientation of radial cutting edges.

FIG. 5 shows the obtained hole shapes as shown in FIGS.
Diagram corresponding to (c)

FIG. 6 is a perspective view showing a main part of a tool according to a second embodiment of the present invention.

[Explanation of symbols]

 1 Drilling Tool 2 Shank 3 Main Body 4, 5, 6, 8, 9 Cutting Blade 7 Core Discharge Port

Claims (2)

[Claims] 1. A main body connected to a shank is a cylinder concentric with a rotating shaft, a tip edge of the cylinder is a cutting blade, and a tip of the cylinder is a radial cutting blade protruding from an inner surface of the cylinder to at least a center of the cylinder. A rotary drilling tool that is equipped with. 2. A main body connected to the shank is a cylinder concentric with the rotary shaft, a cutting edge extending from the inner diameter surface to the outer diameter surface is provided at the tip of the cylinder, and the cylinder tip is provided with at least the center of the cylinder from the inner surface of the cylinder. A rotary drilling tool that is equipped with a radial cutting edge that projects up to.