JP2001138120A - Core drill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a core drill at a low cost, by connecting a previously molded tool steel-made cutting edge chip to a chip connection surface in a lower end of a core unit and simplifying a production process. SOLUTION: A cutting chip discharge groove 4 is cut formed in the external periphery of a thickness part 3 formed in a lower part 2 of a core unit 1, a chip connection surface 5 is formed in a lower end of the core unit, and a cutting edge chip 6 is connected to a cutting edge 7 appearing in the cutting chip discharge groove 4 to this chip connection surface 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a core drill used for drilling a relatively large diameter hole mainly in a metal material or a nonmetal material, and more particularly, to a core drill formed at a lower end of a core body. The present invention relates to a core drill in which a plurality of cutting blade tips formed in advance are joined to a tip joining surface.

[0002]

2. Description of the Related Art Various types of core drills have been proposed for drilling relatively large-diameter holes in metal materials and nonmetal materials. As a core drill of this type, a configuration in which a plurality of cutting blades are provided at intervals at the lower end edge of a core body made of tool steel, and a chip discharge groove is formed on the lower periphery of the core body corresponding to these cutting edges. There are things.

[0003]

By the way, the above-mentioned core drill, in which the entire core body is made of tool steel and a plurality of cutting blades are provided directly at the lower end edge of the core body, has been worn by use. Since the cutting edge can be polished multiple times, the service life of the core drill can be extended, but not only is the tool steel itself expensive, but also the processing of each cutting edge, especially the inner peripheral surface of the cutting edge Is difficult to process and the production cost is high.

[0004]

Therefore, in order to solve the above-mentioned problems, a core drill according to the present invention is formed by cutting a plurality of chip discharge grooves on an outer periphery of a thick portion formed at a lower portion of a core body at intervals. Further, a chip joining surface is formed at the lower end of the core body, and a cutting edge tip is joined to the chip joining surface with a cutting edge facing each chip discharge groove.

According to the core drill of the present invention having the above-described structure, a gap is formed between the front and rear cutting edges on the chip joining surface of the core body, and chips generated by the drilling operation are discharged from this gap. It moves to the groove and is discharged smoothly. Here, if a configuration in which the chip joining surface is inclined downward from the inside toward the outside is adopted, the chips generate an inducing action toward the chip discharge groove by the inclined chip joining surface, so that the chips are removed. Discharge is performed more smoothly. Further, since the core drill itself is formed by joining a plurality of cutting blade tips formed in advance to the tip joining surface of the core body, the production process of the core drill can be simplified and provided at a low cost.

[0006] When the cutting edge provided on the cutting edge chip has a single form, the particle size of the chips generated in the drilling operation increases depending on the type of the object to be drilled, and the chips are not smoothly discharged, and are accumulated at the cutting edge. Not only does the cutting resistance increase, but also the quality of the drill hole deteriorates depending on the properties of the chips. Therefore, the cutting blade is divided into an outer blade and an inner blade, and the inner blade precedes the outer blade in the rotation direction, and the rake face on the front surface of the outer blade matches the rear wall of the chip discharge groove,
Or, it is positioned so as to protrude slightly in the rotation direction from the rear wall surface of the chip discharge groove, and the outer surface of the inner cutter between the inner cutter and the outer cutter is matched with the bottom surface of the chip discharge groove, or If a configuration in which the projection is positioned so as to project slightly outward from the bottom surface of the discharge groove is employed, chips generated by the outer blade and the inner blade that are successively arranged in the drilling operation can be subdivided. The chips generated by the inner blade are generated before the chips generated by the outer blade, and the chips generated by the inner blade may be guided by the chip joining surface. The chips generated by the cutting move to the chip discharge groove with little resistance. Accordingly, both chips are discharged from the common chip discharge groove without delay with a time lag, and the chips are smoothly discharged regardless of the type of the object to be drilled.

In addition, a relief is formed on the side surface of the cutting edge to form a protruding side portion in contact with the cutting edge on the front side surface of the chip, and the protruding side portion is processed to be thinner by turning the protruding side portion toward the base side. With the configuration with the counter surface, the cutting resistance by the cutting blade can be reduced and the drilling efficiency can be increased. In particular, when a cutting edge is cut into the core body itself made of tool steel as in a conventional core drill, a protruding side portion is formed on the outer surface of the cutting edge portion, and the protruding side portion is directed toward the base. It is common practice to provide a second beveled surface by processing to reduce the wall thickness. However, a protruding side surface is formed on the front inner side surface of the cutting edge, and the protruding side surface is formed so as to face the base. When the thickness is reduced, this processing is performed inside the core body, so it is extremely difficult,
It was impossible in terms of cost, and it had to be said that it was impossible physically for a small diameter one. In the present invention, since a preformed cutting edge tip is used, the cutting edge tip can be provided with the desired second chamfered surface regardless of the inner and outer surfaces, so that the cutting resistance is drastically reduced. Thus, the drilling efficiency can be increased.

In setting the inward clearance angle of the lower surface of the cutting blade, there is some variation in the optimum angle depending on the properties of the object to be drilled. Therefore, in consideration of the versatility of the core drill from a practical point of view, it is preferable to set the inward clearance angle of the lower surface of the cutting blade to about 20 degrees. With such a configuration, the sharpness of the cutting edge tip is sufficiently exhibited in the drilling of an object to be drilled in which the core drill according to the present invention is frequently used, the drilling efficiency is enhanced, and stable drilling is realized.

Further, from a practical point of view, in the core drill of the present invention, the processing of the core body is performed by cutting the chip discharge groove and processing the lower end surface of the core body into an inclined surface (taper surface) to form a chip joining surface. Therefore, compared to a conventional core drill in which the entire core body is made of tool steel, the productivity can be increased and the cost can be reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a side view of an essential part of a core drill according to an embodiment of the present invention, in which a part of a core drill is omitted.
Is a bottom view of the core drill, FIG. 3 is an enlarged bottom view of the cutting tip, FIG. 4 is an enlarged side view of the cutting tip viewed from the outside, FIG.
FIG. 3 is a schematic end view of a main part of a core drill when a cutting edge tip is viewed from a rotation direction.

In the drawings, reference numeral 1 denotes a core body of a core drill according to the present invention. The core drill is basically composed of the core body 1 and a shank (not shown) connected to the base thereof.

A thick part 3 is formed in the lower part 2 of the core body 1, and a plurality of chip discharge grooves 4 are formed on the outer periphery of the thick part 3 with an interval therebetween. A chip joining surface 5 is formed, and a cutting blade chip 6 made of tool steel, which is formed in advance, is joined to the chip joining surface 5 with a cutting edge 7 facing each chip discharge groove 4. Here, as shown in FIG. 5, the chip bonding surface 5 may be inclined downward from the inside toward the outside.

Cutting edge 7 of cutting edge tip 6 in embodiment
The outer cutter 7a extends substantially on the extension line of the bottom surface 4b of the chip discharge groove 4.
And an inner blade 7b. The inner blade 7b precedes the outer blade 7a in the rotation direction, and the rake face on the front surface of the outer blade 7a is
Or it is positioned so as to protrude slightly in the rotational direction from the rear wall surface 4a of the chip discharge groove 4 and the outer surface of the inner blade between the inner blade 7b and the outer blade 7a is used for chip discharge. It is aligned with the bottom surface 4b of the groove 4 or positioned so as to protrude slightly outward from the bottom surface 4b of the chip discharge groove 4.

Further, in consideration of the versatility of the core drill from a practical point of view, in the embodiment, as shown in FIG. 5, the clearance angle α of the lower surface of the cutting edge for the inward direction is set to about 20 degrees.

The cutting edge chip 6 is subjected to relief processing on the inner and outer side surfaces 9 and 10 so as to protrude to the outside of the tip front corresponding to the outer blade 7a and the inside of the chip front corresponding to the inner blade 7b. 9a and 10a, and these projecting side portions 9
a, 10a are processed to be thinner toward the base to provide a second chamfered surface.

In the drilling of the core drill according to the present invention having the above-described structure, chips are discharged from the chip discharge groove 4 due to the guiding action of the inclined chip joining surface 5 exposed between the front and rear cutting edges 6 at the chip joining surface 5. It is discharged smoothly without delay. Further, since the cutting edge 7 of the cutting edge tip 6 is divided into an outer blade 7a and an inner blade 7b before and after being divided, chips generated by the outer blade 7a and the inner blade 7b are finely divided regardless of the type of the object to be drilled. And the chips are smoothly discharged from the common chip discharge groove 4 with a time lag. Further, in the present invention, since the cutting blade tip 6 formed in advance is bonded to the chip bonding surface 5 of the core body 1, the cutting blade chip 6 can be formed as desired regardless of the inner and outer surfaces of the cutting blade chip 6 regardless of its processing. A chamfer can be provided, which can drastically reduce the cutting force.

[0018]

The present invention is embodied in the form described above. According to the present invention, the basic configuration of a core drill is substantially the same as that of a known core drill, and therefore, the use of the core drill is well known. It can be used like a core drill.

According to the core drill of the present invention,
Since a plurality of cutting blade tips formed in advance are joined to the tip joining surface of the core body, the production process can be simplified and provided at a low cost. In addition, the cutting edge of the present invention, which can be easily attached to the cutting edge tip of the present invention, can be easily attached to the second cutting surface, which is considered to be difficult to process with the conventional core drill because of its structural surface. Drilling efficiency can be increased by drastically reducing the resistance.

[Brief description of the drawings]

FIG. 1 is a side view of a main part of a core drill according to an embodiment of the present invention, in which a part of a core drill is omitted.

FIG. 2 is a bottom view of the core drill.

FIG. 3 is an enlarged bottom view of the cutting blade tip.

FIG. 4 is an enlarged side view of the cutting edge tip as viewed from the outside.

FIG. 5 is a schematic end view of a main part of the core drill when the cutting edge tip is viewed from a rotation direction.

[Explanation of symbols]

 Reference Signs List 1 core body 2 lower part of core body 3 thick part 4 chip discharge groove 4a rear wall surface of chip discharge groove 4b bottom surface of chip discharge groove 5 chip joining surface 6 cutting edge chip 7 cutting blade 7a outer blade 7b inner blade 8 inner blade outer surface 9a protruding side surface portion 10a protruding side surface portion

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[Procedure amendment]

[Submission date] May 26, 2000 (2005.2.
6)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction contents]

[0004]

Therefore, in order to solve the above-mentioned problems, a core drill according to the present invention is formed by cutting a plurality of chip discharge grooves on an outer periphery of a thick portion formed at a lower portion of a core body at intervals. , And descend from the inside to the outside at the lower end of the core body
A chip joining surface inclined at a gradient is formed, and a cutting edge is joined to the chip joining surface with a cutting edge facing each chip discharge groove.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

According to the core drill of the present invention having the above-described structure, a gap is formed between the front and rear cutting edges on the chip joining surface of the core body, and chips generated by the drilling operation are discharged from this gap. It moves to the groove and is discharged smoothly. Here, the chip bonding surface, so that is inclined to the downward slope toward the outside from the inside, the chips discharging cuttings generated the inducing action towards chip discharge groove by the inclined chip bonding surface It will be done more smoothly. Further, since the core drill itself is formed by joining a plurality of cutting blade tips formed in advance to the tip joining surface of the core body, the production process of the core drill can be simplified and provided at a low cost.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction contents]

A thick part 3 is formed in the lower part 2 of the core body 1, and a plurality of chip discharge grooves 4 are formed on the outer periphery of the thick part 3 with an interval therebetween. A chip joining surface 5 is formed, and a cutting blade chip 6 made of tool steel, which is formed in advance, is joined to the chip joining surface 5 with a cutting edge 7 facing each chip discharge groove 4. Here, the chip bonding surface 5, as shown in FIG. 5, Ru is inclined from the inside to the downward slope toward the outside.

Claims (5)

[Claims] 1. A plurality of chip discharge grooves are formed in the outer periphery of a thick portion formed at a lower portion of a core body at intervals, and a chip joining surface is formed at a lower end of the core body. A core drill characterized by joining a cutting edge tip with a cutting edge facing a chip discharge groove. 2. The cutting blade is divided into an outer blade and an inner blade, wherein the inner blade precedes the outer blade in the rotation direction, and a rake face on a front face of the outer blade matches a rear wall surface of the chip discharge groove, or Position it so that it protrudes slightly in the rotational direction from the rear wall of the chip discharge groove,
The outer surface of the inner cutter between the inner cutter and the outer cutter is aligned with the bottom surface of the chip discharge groove or is positioned so as to protrude slightly outward from the bottom surface of the chip discharge groove. The described core drill. 3. A cutting side surface of a cutting tip is subjected to relief processing to form a protruding side surface on a front side surface of the cutting tip, the protruding side surface being directed toward the base side to reduce the wall thickness. The core drill according to claim 1 or 2, wherein a count surface is provided. 4. The core drill according to claim 1, wherein an inward clearance angle of the lower surface of the cutting blade is set to about 20 degrees. 5. The core drill according to claim 1, wherein the chip joining surface is inclined downward from the inside to the outside.