JP2005279848A - Burr suppressing drill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drill for reducing push-out of burrs at the time of passing through a hole by guiding cut chips having simple structures into a drill groove, smoothly performing a cutting, and reducing the push-out to the front of a drill at the time of the cutting, and suppressing generation of burrs at the time of drilling, even when a difference in level exists on a machined rear surface and a part of the hole covers the difference in level. <P>SOLUTION: In this drill, a twist angle of a twist drill groove main body is ≥15° and ≤35°, a cutting edge for suppressing burrs is provided at a distal end of the drill, a twist angle of the cutting edge for suppressing burrs is ≥0° and ≤10° in front view, and the length of the cutting edge for suppressing burrs is made ≥0.1 times and ≤0.5 times of the diameter of the drill from a cutting edge ridge toward a base end side. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a drill that suppresses burrs at the time of penetrating a hole by reducing extrusion to the front of the drill when drilling a metal and a non-ferrous metal with a drill.

When drilling metal and non-ferrous metal through-holes with a drill, burrs are generated on the back side of the hole. In particular, carbide drills are honed corresponding to a torsion angle of minus 20 to 30 degrees to prevent chipping at the tip of the cutting edge. Therefore, the pushing action to the front of the drill at the time of cutting is strong, and a large burr is generated at the time of hole penetration. As a method for removing the back burr, Patent Document 1 is devised to provide a burr cutting blade that goes in and out by the elasticity of the spring in the land near the tip of the drill, and to remove the burr at the time of pulling back after drilling. A drill is used. The drill described in Patent Document 1 has a complicated structure and is difficult to manufacture with a small-diameter drill, and this method cannot be used when there is a step on the processed back surface and a part of the hole covers the step.
Japanese Patent Laid-Open No. 2003-127017

  The present invention relates to the suppression of burr generation, and the structure is simple and the cut chips are guided into the drill groove to smooth the cutting, and the extrusion to the front of the drill at the time of cutting is reduced. An object of the present invention is to provide a drill that can suppress the occurrence of burrs during drilling even when there is a step on the back surface of the machining and a part of the hole covers the step.

  In the present invention, the twist angle of the twist drill groove main body is 15 ° or more and 35 ° or less, and the drill tip has a cutting edge for suppressing burr, and the twisting angle of the cutting blade for suppressing burr is 0 ° or more in a front view. A burr suppressing drill having a cutting edge length for burr suppression of 10 ° or less and 0.1 to 0.5 times the drill diameter from the cutting edge to the base end side. is there.

  The present invention relates to a drill that suppresses the occurrence of burrs when drilling through-holes by reducing the push forward of the drill during cutting.

When drilling metal with a carbide drill, if the twist angle of the twist drill groove body is 15 ° or less, the screw effect due to the twist angle is poor, and the risk of breakage due to clogging of chips is great. If the angle is 35 ° or more, the torsion angle is large, so that the rigidity of the drill is lowered, and the drill breaks due to impact during penetration, or chipping or the like is induced on the blade edge by vibration during cutting. Also, when drilling metal and non-ferrous metal through-holes with a drill, burrs are generated on the back side of the hole. Especially with carbide drills, honing corresponding to a torsion angle of minus 20 to 30 ° is necessary to prevent chipping at the tip of the cutting edge. Since part of the chips cut at the time of drilling tries to go into the drill flank side, the pushing action to the front of the drill works strongly, and a large burr is generated when the hole penetrates.
The drill of the present invention smoothly guides the chips cut at the tip of the drill cutting edge into the drill groove and prevents the chips from getting into the drill flank side, so that the twist angle is 0 ° or more and 10 ° or less. Has a cutting edge. When the twist angle of the burr-suppressing cutting edge is 0 ° or less, the cut chips are pushed into the flank side, and the generation of burrs is promoted by the pushing action toward the front of the drill. When the twist angle is 10 ° or more, the twist angle increases. The cutting edge strength of the control cutting edge is insufficient, and chipping or the like occurs at the cutting edge due to impact during penetration. Therefore, the twist angle of the burr suppressing cutting edge provided at the tip of the drill cutting edge was set to 0 ° or more and 10 ° or less.
Next, the burr-suppressing cutting edge length from the cutting edge to the base end is less than 0.1 times the drill diameter, the drill cutting edge reinforcement surface is small, and chipping or the like occurs at the cutting edge due to impact during penetration . If it is 0.5 times or more, the drill cutting edge strengthening surface becomes large, and chips cut at the cutting edge tip do not flow smoothly into the drill groove, increasing the cutting resistance, which may induce vibration and abnormal noise during cutting. For this reason, the burr-suppressing cutting edge length from the cutting edge to the base end side is set to 0.1 to 0.5 times the drill diameter.
Furthermore, when the bending strength of the cemented carbide constituting the drill is 3 GPa or less, the strength of the material is insufficient, and chipping or the like occurs at the cutting edge due to impact during penetration, and stable cutting with the burr-suppressing cutting edge shape is maintained. I can't. Therefore, the bending strength of the cemented carbide constituting the drill was set to 3 GPa or more. Hereinafter, based on an Example, this invention is demonstrated concretely.

(Example 1)
As Example 1, made of cemented carbide, TiAlN coating, drill diameter = 8.0 mm, tip angle = 140 °, drill groove length = 45 mm, drill overall length = 85 mm, core thickness = 2.0 mm, twist angle of drill groove main body = 30 °, burr-suppressing cutting edge length from cutting edge to base side = 2.4 mm, each shape using twist angle (β) of burr-suppressing cutting edge in front view as shown in Table 1 With a single tool, wet using a vertical machining center with a rotation speed of 2000 min ^-1 , feed = 300 mm / min and a thickness of 4.5 mm and a thickness of 4.5 mm, each processing 5 holes, and the maximum average height of the back burr Table 1 shows the state of the cutting edge after cutting.

  In Comparative Example 5, an abnormal sound was generated when the five holes were penetrated. From Table 1, according to the present invention, the maximum average height of the back burr was small, and there was no abnormality in the state of the cutting edge after cutting. Shapes other than the present invention had a large maximum average height of back burrs, or chipping occurred on one side of the cutting edge after cutting.

(Example 2)
Using the drill of Example 1, the twist angle (β) of the burr-suppressing cutting edge in the front view is 5 °, and the burr-suppressing cutting edge length (L ) In Table 2, using one tool for each shape, drilling in the same way as in Example 1, the maximum average height of the back burr, the stability of cutting, and the state of the cutting edge after cutting The survey is conducted and the status is shown in Table 2.

  From Table 2, in the present invention example, the maximum average height of the back burr was small, there was no abnormality in the state of the cutting edge after cutting, and the cutting was stable. In the comparative example, abnormal noise was generated during cutting, chipping was observed on one side of the cutting edge, and vibration and abnormal noise were generated during cutting, which was unstable.

FIG. 1 shows a front view of the present invention. FIG. 2 shows a top view of FIG.

Explanation of symbols

1: Burr-suppressing cutting edge 2: Torsion angle (β) of burr-suppressing cutting edge
3: Burr suppression cutting edge length (L)
4: Cutting edge ridge 5: Twist angle of drill groove body

Claims (3)

The twist angle of the twist drill groove main body is 15 ° or more and 35 ° or less, and has a cutting edge for burr suppression at the tip of the drill, and the twisting angle of the cutting blade for burr suppression is 0 ° or more and 10 ° or less in front view, A cemented carbide burring suppression drill characterized in that the cutting edge length for suppressing burrs is set to be 0.1 to 0.5 times the diameter of the drill from the cutting edge to the base end side. 2. The burr suppressing drill according to claim 1, wherein the bending strength of the cemented carbide used for the drill is 3 GPa or more. 3. The burr suppression drill according to claim 1, wherein a hard material such as TiN, TiCN, TiAlN or the like is formed on a part or all of the burr suppressing cutting edge.

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