JP2001341022A - Drill for perforating high hardness material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a twist drill perforating a material with hardness of a degree of structural steel or a pre-hardened material by a drill with superior chip discharge ability enhancing cutting speed, feed rate, and efficiency, reducing burrs generated in the perforating, and eliminating deburring after the perforating. SOLUTION: In a drill twist drill 1 for perforating high hardness material made of coated cemented carbide, a helix angle 2 is provided at 10 to 45 deg., a tip cutting edge 3 is formed protrusively as viewed from a tip of the drill, the tip cutting edge is provided 1 to 10% of a cutting part diameter to the rear in a rotating direction with respect to an imaginary line connecting a most protruding part of the protruding part and a thinning edge, and a face of a connecting part of the tip cutting edge and an outer circumference is chamfered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a super hard drill,
Particularly, the present invention relates to a super-hard drill which is hardened and is suitable for drilling a high-hardness material having an HRC of 30 to 60.

[0002]

2. Description of the Related Art With the demand for higher precision and higher quality of dies, direct drilling of high-hardness materials has been increasing in consideration of expansion of pre-hardened materials. The pre-hardened material has a hardness of about 45 HRC in advance by heat treatment. Unlike the original hardened steel, the pre-hardened material is liable to cause troubles such as chipping when a structural steel drill is used, and is used for high-hardness materials of HRC60 or more as described in JP-A-7-80714. Not as good as using a drill.

Further, when cutting pre-hardened steel,
It is also required not to generate extra burrs and the like. In order to reduce these burrs, especially in the above-described example, a countermeasure has been taken to provide a super-hard drill that does not cause so-called chipping on the surface on the side where the drill comes out, in the case of drilling a through hole. ing.

[0004]

However, with a hardness of about the same degree as that of a pre-hardened material, it is desired that a drill having a higher chip discharge performance, a higher cutting speed and a higher feed speed, and higher efficiency be used. It is also desired to reduce the occurrence of burrs in the drilling process and to eliminate deburring after drilling. Therefore, the invention of the present application is a structural steel, a work material having a hardness of about a pre-hardened material, a drill excellent in chip evacuation, a high cutting speed, a high feed speed, high efficiency,
It is a further object of the present invention to provide a twist drill that reduces the occurrence of burrs in drilling and does not perform deburring after drilling.

[0005]

In order to solve the above-mentioned problems, according to the present invention, a drilling tool according to the present invention is provided with a twist twist drill for drilling a high-hardness material made of a coated super-hard alloy. 10 ° to 45 °, and when viewed from the tip of the drill, the tip cutting edge is made convex, and the tip cutting edge is cut with respect to an imaginary line connecting the most convex part of the convex part and the thinning blade. A drill for drilling high-hardness materials, provided on the rear side in the rotation direction of 1 to 10% of the diameter and having a chamfered surface at the joint between the tip blade and the outer periphery, which supplements the strength of the corner portion. is there.

First, the torsion angle, which is the rake angle in the axial direction, is:
If it is large, sharpness can be improved, but strength is reduced. If the helix angle is less than 10 degrees, the cutting resistance is increased as in the case of a straight blade, so that the margin for enlargement is increased and the hole accuracy is reduced. If the torsion angle exceeds 45 degrees, the discharge of chips is hindered, so the range was 30 degrees to 45 degrees. In addition, as shown in FIG. 2, by smoothly connecting the lowering of the strength with the tip blade which is the rake angle in the radial direction, the lowering of the strength is compensated for by smoothly connecting the convex portion to the chamfered shape, so that sufficient cutting edge strength is obtained. In particular, this chamfer not only improves the chip resistance of the tool and prolongs the service life, but also suppresses the occurrence of chipping when cutting through holes and reduces the generation of burrs. Can be reduced. Next, since the tip cutting edge from the convex portion to the thinning cutting edge affects the dispersion and reduction of cutting resistance and the restraint of chips, the tip cutting edge corresponds to an imaginary line connecting the most convex portion of the convex portion and the thinning blade. And the cutting edge at the tip
Provided on the rear side in the rotation direction by 10%. The reason why the tip cutting edge is 1 to 10% of the blade diameter in the rotation direction rear side is that if it is less than 1% of the blade diameter, as in the case of the linear cutting edge, there is no effect on the generation of chips, and the cutting edge is 10% of the blade diameter. %, The land width becomes relatively thin and the strength is inferior.
The range was 10%. Furthermore, by making the tip cutting edge convex when viewed from the tip of the drill, the cutting resistance received by the tip cutting edge is forcibly divided into an outer peripheral side and an inner peripheral side, and further, a connecting portion on the outer peripheral blade side. Can be provided at a large angle, so that the strength of the connecting portion between the tip cutting edge and the outer periphery can be increased. Further, the generated chips are constrained by the convex portions and are forcibly moved in the axial direction of the chip discharge grooves and discharged. In particular, the convex part can be controlled by the radial position of the most convex part and the convex part difference in the front view shown in FIG. The position of the most convex portion may be any position between 98% of the diameter and the end of the thinning blade, or preferably 70 to 9 of the diameter.
8%. If it exceeds 98%, there is not enough room for the connecting portion with the outer peripheral end, and it is difficult to connect in a curved shape.
On the other hand, if it is less than 70%, the connection with the thinning blade cannot be performed smoothly. Further, the shape of the most convex portion is preferably provided in a gentle curved shape. At this time, the difference is defined as shown in FIG. The difference between the most protruding portion of the protruding portion and the outer peripheral blade is substantially less when the blade diameter is less than 0.5%, and when the diameter exceeds 20%, the protruding portion is excessively formed. 0.5
-20%. The direction in which the chips move can be constrained in the axial direction by the position and difference of the projections. Further, in order to further ensure the strength, a cutting edge treatment as performed by a twist drill made of cemented carbide may be performed.

[0007] The cutting edge treatment is used for a twist drill made of a brittle material such as a cemented carbide, but there is hardly any application to a high speed tool steel drill.
High-speed tool steel tools have high strength and are unlikely to cause chipping or the like even if a sharp blade is adopted.
When the torsion becomes severe, if the cutting edge processing is performed on a part of the cutting edge, the plus surface becomes larger. The same effect is obtained when the cutting edge treatment is performed before or after coating, but when performed before coating, about 0.002 to 0.20 mm can be applied. The form is near the thinning of the tip blade,
The range was 0.002 to 0.20 mm, including differences depending on locations such as the vicinity of the outer periphery and application of negative honing treatment and the like. 0.
If it is less than 002, the effect of the cutting edge treatment is small, and
If it exceeds mm, it will be too large. In addition, the cutting edge treatment can be performed by a known method such as a brush or magnetic polishing. Furthermore, when performing after coating,
The processing amount of the cutting edge was 0.1 to 10 μm. 0.1μ
When the diameter is less than m, the effect is not substantially obtained. When the diameter exceeds 10 μm, the film is completely removed, and the superhard alloy as the base is excessively exposed.

Next, by making the tip blade convex, the cutting resistance received by the tip blade is forcibly divided into the outer peripheral side and the inner peripheral side, and the connecting portion on the outer peripheral blade side is provided at a large angle. Therefore, the strength of the connecting portion between the tip blade and the outer periphery can be increased. Further, the generated chips are constrained by the convex portions and are forcibly moved in the axial direction of the chip discharge grooves and discharged. Further, as shown in FIG. 5, the outer peripheral end of the tip blade is connected to the most convex portion of the above-described convex portion in a curved shape and provided at a larger angle. By increasing the angle, the chipping resistance of the cutting edge is increased.

The core thickness of the drill is 0.20D to 0.35D
Range. If it is less than 0.20D, the rigidity of the tool is insufficient, and the precision of the enlargement allowance of the work material entrance at the time of drilling becomes poor.
If it exceeds 0.35D, the space of the groove itself becomes too narrow, so that the contact with the wall increases, the cutting resistance increases, and the chip discharge property deteriorates, so that chip clogging is likely to occur. Further, the groove width ratio is 50 to 50 (in the sectional view, the groove width of the chip discharge groove is divided by the tool outer peripheral length and expressed as a percentage).
65%. Here, when the groove width ratio is less than 50%, the groove width becomes narrow in combination with strong torsion, causing chip clogging. When the groove width ratio exceeds 65%, the land portion becomes narrower due to the wide groove width, and the strength decreases. Therefore, the groove width ratio is 50 to 65
%. Furthermore, a large groove width ratio can be adjusted by the shape of the heel portion of the groove. By forming the tip of the heel portion in an arc shape, the groove width ratio can be increased and the contact of the chip with the inner wall as described above can be reduced.

Although the twist drill of the present invention has been described using high-speed steel, powdered high-speed steel is more preferred. Since the carbide has a finer grain size as compared with the ordinary ingot high-speed steel, it is advantageous for the drill of the present invention having a large torsion angle. In addition, it is possible to apply the shape of the cutting edge treatment by utilizing the torsion even in the case of the melted high-speed steel. Further, a coating is essential for a highly ductile material such as stainless steel, and a coating known in the present invention, for example, TiN or TiAlN
A film formed using a physical vapor deposition method such as described above is suitable. In particular, a coating of molybdenum disulfide, a solid lubricant, or the like, which is rich in lubricity, is effective in the vicinity of the chisel of the tip blade where chip welding and pressure bonding are likely to occur.

By employing a twist angle of 10 to 45 degrees, sharpness and high hole accuracy can be obtained. Furthermore, in order to further improve the hole accuracy, the thinning shape is made a shape with higher centripetality. As shown in FIG. 5, the thinning angle is large, and as shown in FIG.
By providing a negative angle of 5 degrees or more and providing a sufficient distance to the blade groove so as to smoothly tie, chips are prevented from being clogged, and in combination with the convex action of the tip blade, the chips are discharged rearward in the axial direction. You. Hereinafter, the present invention will be specifically described based on examples.

[0012]

1 is a front view of a drill according to an embodiment of the present invention, FIG. 2 is a top view of the drill shown in FIG. 1 rotated by 90 degrees, and FIG. 3 is a front view of FIG. The twist drill 1 according to the present embodiment is made of ultra-fine-grain cemented carbide, and has a blade diameter of 8 mm.
The two blades, the torsion angle 2 was 40 degrees, the core thickness was 25% D, sufficient drill rigidity was obtained, and after honing treatment, TiAlN was coated. As shown in FIG.
The protruding part 4 is provided on the tip cutting edge 3 around the
6 is 2% of the diameter. Further, the outer peripheral end 7 of the tip cutting edge 3 is smoothly connected in a chamfered shape, and a chip discharge groove 8 is formed. The thinning of the tip blade was of a cross type.

In the cutting test, the hardness of the work material was HR.
C45 pre-hardened steel was used. Cutting speed is 20m /
min, the feed amount was 0.10 mm / rev. The processing length of the hole was a blind hole of 16 mm twice the drill diameter. This specification is for grasping the fracture resistance of the outer peripheral portion of the drill. For comparison, a drill having the same specifications as the above-mentioned drill but without chamfering was also manufactured, and a test was carried out with Konashi cutting specifications. After machining 10 holes, the condition of the cutting edge was confirmed.
First, in the example of the present invention, there was no chipping at the outer peripheral end of the tip cutting edge, and normal wear was exhibited. In the comparative example, the chipping of the outer peripheral end of the leading edge became large, and the cutting test was stopped. Further, the cutting test was continued, and the condition at the time of machining 100 holes showed normal wear without chipping at the outer peripheral end of the tip cutting edge.

Using a sample having a position of 50% of the most convex portion, the difference 6
Were prepared with 0.5%, 2%, 3%, 4%, 5%, and 10% of the diameter, and the cutting test was performed in the same manner. As a result, only the sample having a 10% difference 6 caused a defect in the first hole, and the others showed normal wear. Concentration was lost due to the overhang of the projections. The test was further continued, and in the 100-hole processing, abrasion of the convex portion was increased in the sample having the difference 6 of 5%.
Other samples showed normal wear. Further, when the test was continued up to 200 holes, the chip morphology changed in the sample having a difference 6 of 0.5%, and continuous chips began to be discharged. Other samples showed normal wear.

After coating with 5 μm of TiAlN using the twist drill used in the above embodiment, the coated edge was treated by magnetic polishing. Since the unevenness of the coating surface after coating intersects with the cutting edge after coating by the edge processing, the unevenness can be smoothed and the edge line of the cutting edge can be smoothed. In addition, in addition to the effect similar to the chisel,
Droplets and large particles existing on the surface of the coating can be smoothed out, and the surface of the coating can be smoothed. In particular, in the case of a ductile material such as mild steel, the projections such as the droplets of the film cause pressure bonding and the like, so that the effect is large.

Although the above embodiment has been described using high-speed steel, the present invention is not limited to this, and the present invention is similarly applicable to a solid carbide type or a throw-away type drill. Applicable.

[0017]

As described above, by using the drilling tool according to the present invention, machining with small cutting resistance and high hole accuracy (enlargement allowance) can be performed, and wear is reduced by combination with the cutting edge treatment. Provides stable and excellent tool life.

[Brief description of the drawings]

FIG. 1 shows a front view of a drill according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of FIG. 1;

FIG. 3 shows a front view of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Twist drill 2 Helix angle 3 Tip blade 4 Convex part 5 Most convex part 6 Difference between the most convex part and outer peripheral part 7 Peripheral end of distal end blade 3 8 Chip discharge groove

Claims (2)

[Claims] 1. A twist twist drill for drilling a high-hardness material made of a coated super-hard alloy, the twist angle of which is 10
Degrees to 45 degrees, and when viewed from the tip of the drill, the tip cutting edge has a convex shape, and the tip cutting edge has a blade diameter with respect to an imaginary line connecting the most convex portion of the convex portion and the thinning blade. A drill for drilling a high-hardness material, wherein the drill is provided on the rear side in the rotation direction by 1 to 10%, and the connecting portion between the tip blade and the outer periphery is a chamfered surface. 2. The drill for drilling high-hardness material according to claim 1, wherein the chamfer is formed at an angle of 20 ° to a perpendicular to a rotation center line.
A high-hardness material drilling drill provided at an angle of 60 degrees.