JP2005144640A - Drill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drill which reduces a cutting resistance occurring at the time of drilling of an aluminum alloy, and smoothes flow of chips at a thinning portion to suppress welding at the thinning portion by specially designing the shape of the X-shaped thinning. <P>SOLUTION: The drill having the X-shaped thinning 3 is a drill having an oil hole 5 formed therein, and designed such that a thinning bottom 8 is formed into a round portion having a size of 0.04 to 0.12 times a drill diameter, and that a thinning inclination angle α is set to the same as a drill twist angle β. Further a drill groove length portion 7 is coated with a DLC coating amorphous film formed of TiC. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a drill having a function of reducing cutting resistance in drilling an aluminum alloy and smoothing a flow of chips coming out of a thinning portion and suppressing welding of the thinning portion.

The cutting edge shape of a conventional cemented carbide drill with oil holes used for drilling an aluminum alloy is a surface grinding only on the cutting edge surface 1 shown in FIG. In addition to the cutting edge surface 1, a drill with three rake grinding, in which the flank 2 and the thinning 33 are ground, is generally used, 4 is a chisel, and 5 is an oil hole. Further, as shown in FIG. 5A, Patent Document 1 discloses a drill provided with a thinning 23 suitable for a ductile material such as stainless steel and aluminum alloy.
Japanese Patent No. 3263025 Claim 1 and FIG.

  The shape of the cutting edge of a drill used for drilling a conventional aluminum alloy is generally the above-described surface grinding or so-called three rake, but the thrust resistance is increased in surface grinding or three rake grinding. In order to reduce the cutting resistance, an X-shaped thinning 34 as shown in FIG. 6 may be applied. However, when drilling an aluminum alloy, chips remain on the bottom 14 of the thinning portion 34 and the thinning portion 34 is cut. The flow of waste is poor and the biting property is lowered, causing a stepping phenomenon of the drill, or causing breakage due to chip clogging. Moreover, in patent document 1, as shown to Fig.5 (a), although the thinning 23 suitable for ductile materials, such as stainless steel and an aluminum alloy, is shown, the 2nd plane part 12 of this thinning 23 is a rake surface. The chisel portion 4 and the second flat surface portion 12 are processed while being crushed, so there is no effect in reducing cutting resistance.

  The object of the present invention is to devise the shape of the X-type thinning, thereby reducing the cutting resistance in drilling an aluminum alloy, and smoothing the flow of chips in the thinning portion to suppress the welding of the thinning portion Is to provide.

  For this reason, the present invention is characterized in that, in a drill having X-shaped thinning, the thinning bottom portion is an R portion 0.04 to 0.12 times the drill diameter, and the thinning inclination angle is the same as the drill twist angle. The above-described problems of the present invention have been solved by providing a drill that performs. If the bottom of the thinning part R is less than 0.04 times the diameter of the drill, the flow of chips in the thinning part will be worse and the chips will stay. The thinning bottom 8 was limited to an R portion 0.04 to 0.12 times the drill diameter.

  With this configuration of the present invention, in the drilling of aluminum alloy, the X-type thinning portion is provided and the thinning inclination angle is the same as the drill helix angle, thereby reducing the cutting resistance and devising the shape of the X-type thinning. Since the bottom of the part is a gently rounded surface, chips do not flow and stay smoothly, and the drill has a function of suppressing chip welding by smoothing the flow of chips. .

  Preferably, by covering the drill groove length part with a DLC-coated amorphous film made of TiC or SiC, the flow of chips can be made smoother and welding of the thinning part can be suppressed.

FIG. 1 is a schematic perspective view of a main part of a φ6 cemented carbide coated drill of the best mode for carrying out the present invention. The drill of the present invention is a drill having an X-shaped thinning 3, and a thinning bottom portion 8 is formed with a drill diameter. Drill drill with oil hole 5 with 0.04 times to 0.12 times (0.24 mm to 0.72 mm) R part and thinning inclination angle α equal to drill helix angle β 7 is coated with a DLC-coated amorphous film made of TiC or SiC. The drill of FIG. 1 has a drill diameter of 6 mm, a groove length of 120 mm, an overall length of 170 mm, a twist angle β of 30 °, an X-shaped thinning 3 applied to the drill tip, and a thinning bottom 8 of 0.5 mm (0.083 times the drill diameter). ), The inclination angle α of the thinning 3 is 30 °, and the drill is the same as the drill twist angle β of 30 °. If the R at the bottom of the thinning is less than 0.04 times (0.24mm) the diameter of the drill, the flow of chips in the thinning will deteriorate and the chips will stay, exceeding 1.2 times the diameter of the drill (0.72mm) Since the strength of the chisel portion is low, the thinning bottom portion 8 is limited to the R portion that is 0.04 to 0.12 times the drill diameter.
FIG. 2A is an enlarged schematic diagram showing chip flow at the bottom of the thinning of the drill of the present invention shown in FIG. 1 and FIG. 2B of the conventional X-thinning drill of FIG.

A comparative test was performed between the cemented carbide coating drill φ6 of the present invention shown in FIG. 1 and the conventional three-rake grinding cemented carbide coating drill φ6 shown in FIG. 5B. Both were provided with oil holes, and cemented carbide was used as the material. The groove length portion 7 was subjected to DLC coating. A drilling test was performed on the work material ADC12 at a cutting speed of 150 m / min, a feed speed of 800 m / min, a hole depth of 80 mm, using a mist oil agent, and welding of the cutting force and the thinned part was compared.
FIG. 3 shows a cutting resistance graph and a welding comparison photograph of the thinning portion as a result of the drilling test. The conventional product has a large cutting resistance and causes welding at the thinning portion, while the invention product can reduce the cutting resistance and does not show any welding at the thinning portion.

The chip retention and breakage of the chisel portion when the thinning bottom R of the X-type thinning portion was changed were measured for the cemented carbide coating drill φ6 of the present invention shown in FIG. FIG. 4 shows the measurement results. As shown in FIG. 4, the chisel portion was good from 0.24 mm, which was 0.04 times the drill diameter φ6, to 0.72 mm, which was 0.12 times the drill diameter φ6. At 0.12mm, a slight drill chip retention is seen in the chisel part, at 0.016 times the diameter φ6 0.06mm, the chisel part is retained, and at 0.14 times 0.84mm, the chisel part is damaged. It was.
[Effect of Best Embodiment of the Present Invention]

  With this configuration of the present invention, in the drilling of aluminum alloy, the X-type thinning portion is provided and the thinning inclination angle is the same as the drill helix angle, thereby reducing the cutting resistance and devising the shape of the X-type thinning. Since the bottom of the part is a gentle R surface, the chips do not flow and stay smoothly, and the drill has a function of smoothing the flow of chips and suppressing the welding of the thinning part. .

  Preferably, by covering the drill groove length part with a DLC-coated amorphous film made of TiC or SiC, the flow of chips can be made smoother and welding of the thinning part can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic perspective view of a main part of a φ6 cemented carbide coating drill according to the best mode for carrying out the present invention, and a thinning bottom portion 8 is exaggerated and enlarged for convenience of explanation. (A) is an enlarged schematic diagram showing chip flow at the bottom of the thinning of the drill of the present invention shown in FIG. 1 and (b) of the conventional product of FIG. A comparison test between the cemented carbide coating drill φ6 of the present invention shown in FIG. 1 and the conventional three-rake grinding cemented carbide coating drill φ6 shown in FIG. The results of the comparison are shown as a cutting resistance graph and a welding comparison photograph of the thinning part, respectively. The measurement result which measured the chip | tip stay and damage condition of the chisel part when the thinning bottom R of the thinning part was changed for the coated drill φ6 made of cemented carbide of the present invention shown in FIG. 1 is shown. (A) is the front-end | tip part perspective view of the drill which gave the thinning 23 suitable for ductile materials, such as stainless steel and aluminum alloy, in patent document 1, (b) is the front-end | tip part perspective view of the drill which carried out three rake grinding, for convenience of explanation The three-surface grinding surfaces of the cutting edge surface 1, the flank 2 and the thinning 3 subjected to the thinning are indicated by hatching. It is a schematic perspective view of the tip of a drill which shows the shape of a cutting edge of a drill used for drilling a conventional aluminum alloy, only the cutting edge surface 1 is surface ground and the surface is not surface ground on the thinning 13.

Explanation of symbols

3: X-shaped thinning 4: Chisel 8: Thinning bottom α: Thinning inclination angle β: Drill twist angle

Claims (2)

  A drill having an X-shaped thinning, wherein the thinning bottom is an R portion 0.04 to 0.12 times the diameter of the drill, and the thinning inclination angle is the same as the drill twist angle.   The drill according to claim 1, wherein a DLC-coated amorphous film made of TiC or SiC is coated on the drill groove length portion.