JP2014034080A - Drill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drill that prevents the occurrence of burrs in the machined hole periphery at the machining initiation side of a workpiece material and at the machining completed side even in the case of the workpiece material having a curved surface, and at the same time capable of ensuring a hole diameter precision in the depth direction of the machined hole.SOLUTION: A drill 1 has a point angle α of 180 to 181 degrees. The drill 1 has a curved cutting edge 2, and the angle β formed by a straight line L1 extending from the cutting edge 2 to an outer peripheral corner 3 and a straight line L2 extending from a chisel edge 4 to the outer peripheral corner 3 is 18 to 22 degrees. In a land 6, two margins 5a, 5b are provided.

Description

  The present invention relates to a drill mainly used for drilling a work material having an inclined surface or guide holes in a thick work material.

Generally, when drilling a workpiece with an inclined surface using a drill, the surface on which the cutting edge of the drill first bites (contacts) is inclined, so a flat surface is Compared to machining, the drill tends to vibrate when drilling, causing runout. As a result, it was difficult to stably ensure the hole machining accuracy. In order to keep the bottom surface of the machining hole horizontal during countersinking on the work material, the end mill is used first, and the cutting tool is changed from the end mill to the drill when the machining hole of the predetermined depth is finished, For the final machining, a so-called long drill having a relatively long overall length is used to penetrate the machining hole. For this reason, when machining a guide hole in a thick work material, it is necessary to always prepare three types of cutting tools: an end mill, a normal drill, and a long drill.

Therefore, in Patent Document 1, a drill having a tip angle of 170 ° to 180 °, a straight chamfer (chamfer length: 0.1 mm to 1. mm) is formed at the outer peripheral corner portion of the cutting edge composed of a straight portion and a curved portion of a concave portion. 0 mm), and an angle at which the intersecting angle with a straight line extending in the diameter direction from the shaft center is 30 ° to 60 ° is disclosed. By using this drill, it is possible to ensure the hole position accuracy when drilling the inclined surface, and to reduce the chipping of the cutting edge at the outer corner.

Patent Document 2 discloses a drill having two cutting edges, and a land having two margins provided on the land. By using this drill for cutting, it is possible to improve the guide property when biting and penetrating the work material, and to perform hole processing with high finishing accuracy.

  Further, in Patent Document 3, a drill having a tip angle of 170 ° to 190 °, a linear chamfer is provided at the outer peripheral corner portion of the cutting blade having a concave curved portion, and the extension line of the cutting blade and the chamfer are provided. The drill which makes the angle | corner with the straight line which forms a 1 to 20 degree is disclosed. By using this drill, it is possible to improve chip discharge and reduce wear of the outer peripheral corner portion, thereby enabling countersinking.

JP 2004-141970 A JP 2006-205272 A JP 2009-56534 A

However, the drills disclosed in Patent Documents 1 to 3 have a problem that burrs are generated around the machining hole on the machining start side and the machining completion (penetration) side when the work material has a curved surface. At the same time, there is a problem that it is difficult to ensure the hole diameter accuracy in the depth direction of the processed hole.

Therefore, in the present invention, even in the case of a work material having a curved surface, the generation of burrs around the work hole on the work start side and work completion side of the work material is suppressed, and at the same time, the hole diameter accuracy in the depth direction of the work hole is ensured. It is an object to provide a drill that can be used.

In order to solve the above-described problem, in the present invention, the drill has a tip angle of 180 ° to 181 °, the drill has a curved cutting edge, and extends from the cutting edge toward the outer corner. The angle formed by the straight line and the straight line extending from the chisel edge to the outer corner is 18 ° to 22 °, and the land is provided with two margins. By using this drill, whilst maintaining the strength of the cutting edge, it is possible to suppress the deflection of the drill even when drilling a workpiece having a curved surface.

  The second invention is a drill having a groove length of 2 to 5 times the diameter of the drill, and a shank length of 5 to 20 times the diameter of the drill (claim 2). By using this drill, it is possible to perform drilling at a so-called deep position where the distance between the workpiece surface and the machining start surface is long.

As described above, the drill according to the present invention can suppress drill run-out in the drilling of a work material having a curved surface while maintaining the strength of the cutting edge. It is possible to suppress the occurrence of burrs around the processing hole on the side and at the same time to ensure the hole diameter accuracy in the depth direction of the processing hole. In addition, when the drill according to the present invention is applied to a drill whose shank length is 5 times or more of the diameter of the drill, so-called long shank drill, the drill runout is suppressed even in drilling at a deep position, There is also an effect that the hole diameter accuracy in the depth direction of the processed hole can be ensured.

It is a front view of drill 1 which shows an embodiment of the invention. It is an enlarged view of the drill 1 of FIG. It is a right view of the drill 1 which shows embodiment of this invention.

  An embodiment of the present invention will be described with reference to the drawings with an example of a drill. FIG. 1 is a front view of a drill 1 showing an embodiment of the present invention, FIG. 2 is an enlarged view of the drill 1 of FIG. 1, and FIG. 3 is a right side view of the drill 1 showing an embodiment of the present invention.

  As shown in FIG. 1 and FIG. 2, the drill 1 according to the present invention has two cutting edges 2, 2, and the cutting edge 2 exhibits a concave curve on the opposite side to the rotation direction of the drill 1. ing. The outer peripheral corner 3 on the outer peripheral side of the cutting edge 2 is composed of a straight line L1 extending from the cutting edge 2 toward the outer peripheral corner 3 and a straight line L2 connecting the chisel edge 4 and the outer peripheral corner 3 that are the center of the tip of the drill 1. The formed angle β is in the range of 18 ° to 22 °. Further, the deepest position 10 of the recess on the cutting edge 2 exists via a distance (interval) δ and a straight line L3 that is parallel to the straight line L2 that connects the chisel edge 4 and the outer periphery corner 3 and passes through the chisel edge corner 8. doing.

Further, the land 6 of the drill 1 is provided with two margins 5a and 5b of a first margin 5a and a second margin 5b. The second margin 5b rotates the drill 1 more than the first margin 5a. Located behind the direction. The tip angle α, which is an angle formed by the two cutting edges 2 of the drill 1, is formed in the range of 180 ° to 181 ° as shown in FIG. When drilling at a deep position, as shown in FIG. 3, the groove length X is set to be 2 times (2D) or more and 5 times (5D) or less the diameter D of the drill 1, and the length Y of the shank 7 is set. Can be in the form of 5 times (5D) or more and 20 times (20D) or less the diameter D of the drill 1.

  Using a drill according to the present invention and a drill outside the present invention, a cutting test (hereinafter referred to as a main test) is performed on a work material (S50C) having a curved machining start surface, and machining in the depth direction of the machining hole is performed. The amount of hole expansion was measured. The measurement results will be described using Table 1. In this test, the drill according to the present invention has a cutting edge having a tip angle of 180 ° and extending outward from the chisel edge, and a straight line extending from the cutting edge toward the outer corner and a straight line extending from the chisel edge to the outer corner. A drill (hereinafter referred to as a product of the present invention) having two margins (first and second margins) provided on the land was used.

On the other hand, a drill having a tip angle of 180 ° and a curved cutting edge extending outward from the chisel edge as a drill outside the present invention, and a land provided with a margin (hereinafter referred to as a conventional product) Was used. The common specifications of the product of the present invention and the conventional product were a drill diameter of 10 mm, a drill length of 150 mm, and a helix angle of 20 °. As specifications different between the product of the present invention and the conventional product, the groove length of the product of the present invention was 45 mm (4.5D), and the groove length of the conventional product was 33 mm (3.3D). The length of the shank was 105 mm (10.5 D) for the product of the present invention and 117 mm (11.7 D) for the conventional product. Furthermore, the distance (interval) between the straight line that is parallel to the straight line connecting the chisel edge and the outer corner and passes through the chisel edge corner and the deepest position of the recess on the cutting edge is 0.03 mm for the product of the present invention. Was 0.04 mm.

Further, this test was performed under the following processing conditions.
・ Work material S50C (carbon steel)
・ Cutting speed 60m / min
・ Rotation speed 1910min ^-1
・ Feed speed 191mm / min
・ Processing hole depth 20mm (through hole)
・ Cutting fluid Use water-soluble cutting fluid

Table 1 shows the processing hole enlargement amount (unit: 2 mm, 10 mm, and 18 mm deep from the processing start surface of the processing hole in the work material after performing the main test using the above-described product of the present invention and the conventional product. : Mm). Here, the processing hole enlargement amount was defined as the difference between the actually measured processing hole diameter (inner diameter) and the drill diameter (10 mm) used in this test.

  As shown in Table 1, the amount of expansion of the processed hole processed using the conventional drill is 2.186 mm at the depth position of 2 mm from the processing start surface, and the amount of expansion of the processed hole is 2.186 mm at the depth position of 10 mm. The processing hole enlargement amount was 2.196 mm, and the processing hole enlargement amount was 1.764 mm at a depth position of 18 mm. That is, in the depth direction of the machining hole, the machining hole enlargement amount is 1.764 mm to 2.196 mm (corresponding to about 18% to 22% of the cutting tool diameter), and the machining hole enlargement amount is 1 regardless of the measurement position. 0.7 mm or more. Moreover, as a result of visually observing the periphery of the machining hole on the machining start side and the machining completion side of the work material, it was confirmed that burrs were generated around the machining hole on the machining start side.

  On the other hand, when the product of the present invention is used, the machining hole enlargement amount is 0.059 mm (59 μm) at a depth position of 2 mm from the machining start surface, and the machining hole enlargement amount is 0.1 at a depth position of 10 mm. It was 007 mm (7 μm), and the drilling hole enlargement amount was 0.003 mm (3 μm) at a depth position of 18 mm. That is, in the depth direction of the machining hole, the machining hole enlargement amount is 0.003 mm to 0.059 mm (corresponding to 0.03% to 0.59% of the cutting tool diameter), and the machining hole is enlarged regardless of the measurement position. The amount was 0.06 mm (60 μm) or less. Further, as a result of visual observation of the periphery of the machining hole on the machining start side and the machining completion side of the work material, no occurrence of burrs was confirmed around the machining hole on the machining start side and the machining completion side.

From the above test results, the drill has a tip angle of 180 °, the drill has a curved cutting edge, and a straight line extending from the cutting edge to the outer corner and a straight line extending from the chisel edge to the outer corner. By using a drill with an angle of 20 ° and two margins on the land, the generation of burrs around the machining hole on the machining start side and machining completion side of the work material is suppressed and at the same time The hole diameter accuracy in the depth direction was ensured.

DESCRIPTION OF SYMBOLS 1 Drill 2 Cutting edge 3 Periphery corner 4 Chisel edge 5a, 5b Margin (1st margin, 2nd margin)
6 Land 7 Shank D Drill diameter L1 Straight line L2 extending from the cutting edge toward the outer periphery corner Straight line X extending from the chisel edge to the outer periphery corner Groove length Y Shank length α Tip angle β Straight line extending from the cutting edge toward the outer periphery corner Angle formed by a straight line extending from the chisel edge to the outer corner

Claims (2)

A drill having a tip angle of 180 ° to 181 °, the drill having a curved cutting edge, and a straight line extending from the cutting edge toward the outer corner and a straight line extending from the chisel edge to the outer corner. The drill is characterized in that the angle between the lands is 18 ° to 22 °, and the land has two margins. 2. The drill according to claim 1, wherein the groove length is 2 to 5 times the diameter of the drill, and the shank length is 5 to 20 times the diameter of the drill.

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