JP2017177236A - Drilling tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drilling tool that is capable of appropriately and finely fragmenting chips even when machining is carried out at a high feeding speed.SOLUTION: A drilling tool 100 is roughly formed into a columnar shape, and provided with a chip discharge groove 20 formed into a helical shape around its outer periphery, and an intersecting ridgeline 50 between the tip surface 40 of the drilling tool 100 and the chip discharge groove 20 is formed into a stepped shape. The action parts (51, 52, and 53) of the intersection ridgeline 50 concerning cutting are arranged in a stepped manner, angles formed between the action parts (52 and 53) and connection parts (54 and 55) connected to the ends of the action parts (52 and 53) on an outer peripheral side are preferably 60°-120°, and more preferably 60°-90°.SELECTED DRAWING: Figure 1

Description

The present invention relates to a drilling tool.

Conventionally, there has been a drilling tool provided with cutting edges and stepped chip discharge grooves that are divided and arranged in steps as shown in Patent Document 1. Since the drilling tool having such a shape of cutting edge generates chips for each cutting edge, it has an effect on fragmentation of chips and is easy to discharge the chips.

JP 2009-202288 A

When the drilling tool of Patent Document 1 is processed at a high feed rate, the fragmentation effect of the chips is not sufficiently exhibited, and the chips may not be discharged smoothly. Even if an attempt is made to generate finer chips by increasing the number of divided cutting edges, the generated chips may collide with the chips generated by the adjacent cutting edges, which may reduce chip discharge. It was.
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a drilling tool that can be appropriately divided into chips and finer even when processed at a relatively high feed rate.

  The present invention has a substantially cylindrical shape, and includes a chip discharge groove and a tip surface on the outer periphery, a cross-ridge line portion between the tip surface and the chip discharge groove is stepped, and the chip discharge groove is a spiral. It is a drilling tool that is shaped.

FIG. 1 is a perspective view of a drilling tool according to an embodiment of the present invention. FIG. 2 is a perspective view of the drilling tool of FIG. 1 viewed from another direction. FIG. 3 is a side view of the drilling tool of FIG. FIG. 4 is a view of the drilling tool of FIG. 1 as viewed from the tip side. FIG. 5 is a partially enlarged view of FIG. FIG. 6 is an enlarged perspective view of the drilling tool of FIG. 7 is a cross-sectional view taken along the line VII-VII in FIG.

As shown in FIG. 1 to FIG. 7, there are two chip discharge grooves 20 on the outer periphery of a substantially cylindrical drilling tool 100. The tip surface 40 of the drilling tool 100 becomes a flank. A part of the intersecting ridge line portion 50 between the tip portion of the chip discharge groove 20 and the flank 40 becomes a cutting edge.
The chip discharge groove 20 is formed in a spiral shape, and its twist angle is preferably 40 ° or less, and a more preferable range is 20 ° or more and 35 ° or less. When the twist angle is in the above-described range, the strength of the outer peripheral corner of the first cutting edge 51 described later can be secured, and the durability of the drilling tool 100 is improved. In particular, when the twist angle is 20 ° or more and 35 ° or less, in addition to the above-described effects, the balance between the chip discharge property and the rigidity of the drilling tool 100 becomes the best. The definition of the twist angle in the present invention is the same as the definition in JIS B0171 4004.

The outer peripheral surface of the drilling tool 100 is not a uniform curved surface, but has a shape in which the central portion 11 is slightly recessed from the edge portion 12 (hereinafter referred to as “margin”). That is, as shown in FIG. 7, which is a cross-sectional view perpendicular to the central axis C of the drilling tool 100, the outer peripheral surface of the drilling tool 100 has a shape in which the central portion is recessed toward the center of the drilling tool 100 with respect to the margin 12. It has become. The margin 12 has a function of improving the surface roughness of the inner wall surface of the processed hole in addition to the function of stabilizing the behavior of the drilling tool 100 during processing. The number, position, size, and the like for forming the margin 12 are not limited and can be set as appropriate.
As shown in FIG. 4, two spouts 13 through which coolant is injected are formed at the tip of the drilling tool 100. The coolant is supplied from the rear end portion of the drilling tool 100 and is jetted from the jet outlet 13 through a flow path formed in a spiral shape inside the drilling tool 100. In addition, it is also possible to employ | adopt the flow path of a linear coolant as another embodiment.

As shown in FIGS. 1, 2, and 7, the chip discharge groove 20 has a substantially step shape in which more than half of the entire groove has two stepped portions, and is constituted by three groove portions. In the following description, for the sake of convenience, the first groove portion 21, the second groove portion 22, and the third groove portion 23 are sequentially described from the groove portion located on the outer peripheral side of the drilling tool 100. .
Each groove part 21,22,23 is adjacent. The third groove portion 23 is entirely composed of a curved surface. However, the first groove portion 21 and the second groove portion 22 are a curved surface portion and a flat surface extending toward the outer peripheral side of the drilling tool 100 or the above-described curved surface portion. And a curved surface with a smaller curvature.
By forming the first groove portion 21 and the second groove portion 22 in such a shape, the degree of freedom of the shape of the groove is increased, and each chip discharge groove is prevented without hindering the flow of the generated chip. The cross-sectional shape can be minimized. That is, in the first groove portion 21 and the second groove portion 22 as well, it is possible to make a cross-sectional shape in which the whole is similar to the third groove portion 23, but in that case, the first groove portion 21 and the second groove portion 22 The cross-sectional areas of the groove portion 21 and the second groove portion 22 are increased, and the rigidity of the drilling tool 100 is reduced.
Note that the length and the chip discharge groove 20 to be formed stepwise can be appropriately set according to the use mode of the drilling tool 100, but are preferably longer than the depth of the hole to be processed.

As shown in FIG. 4, the tip surface 40 of the drilling tool 100 has a 180 ° rotationally symmetric shape about the central axis C of the drilling tool 100, and the second groove part 22 and the third groove part 23 are A first flank 41 to be connected and a second flank 42 connected to the first groove portion 21 and the first flank 41 and bent so as to have a larger flank angle than the first flank 41. It is configured.
The first flank 41 functions as a flank for a second cutting edge 52 and a third cutting edge 53 described later, and the second flank 42 functions as a flank for a first cutting edge 51 described later.
The clearance angle of the flank corresponding to the corner portion of the first cutting edge 51 located on the outermost periphery of the drilling tool 100 is preferably greater than 0 ° and 15 ° or less. By doing in this way, the fall of the strength of the cutting edge which arises structurally by forming the twisted chip discharge groove | channel 20 can be suppressed. In the drilling tool 100, the spout 13 is formed in the second flank 42. In addition, another embodiment in which the first flank and the second flank are smoothly connected is possible.

In the following description, for convenience, the cutting edge formed at the intersecting ridge line portion of the first groove portion 21 and the second flank 42 will be referred to as a “first cutting edge 51”, and the second groove portion 22 The cutting edge formed at the intersecting ridge line portion with the first flank 41 is referred to as a “second cutting edge 52”, and is formed at the intersecting ridge line portion between the third groove portion 23 and the first flank surface. The cutting edge is referred to as “third cutting edge 53”.
As shown in FIG. 4, when the drilling tool 100 is viewed from the tip, the intersecting ridge line portion 50 between the chip discharge groove 20 and the tip surface 40 has two step portions, and the rear side in the tool rotation direction K toward the outer peripheral side. It is formed in a substantially staircase shape that recedes. In other words, the second cutting edge 52 positioned adjacent to the third cutting edge 53 closest to the center of the drilling tool 100 is positioned relatively rearward in the tool rotation direction, and the second cutting edge 52 is more than the second cutting edge 52. Also, the first cutting edge 51 located next to the first blade 51 is relatively located on the rear side in the tool rotation direction.
In the drilling tool 100, the first cutting edge 51, the second cutting edge 52, and the third cutting edge of the intersecting ridge line portion 50 between the chip discharge groove 20 and the first flank 41 or the second flank 42. The blade 53 is a portion (acting portion) that is actually involved in the generation of chips, and the first connecting portion 54 and the second cutting blade 52 that connect the first cutting blade 51 and the second cutting blade 52 and the third cutting. The second connecting portion 55 that connects the blade 53 does not participate in the generation of chips. That is, the two intersecting ridge line portions 50 have a shape in which portions that are involved in chip generation and portions that are not involved are alternately connected.
As shown in FIG. 5, which is a partially enlarged view of the tip shape, when the drilling tool 100 is viewed from the tip, the second cutting edge 52 and the first connecting portion 54 connected to the outer peripheral end of the second cutting edge 52. The angle α1 formed by is between 60 ° and 120 °. Furthermore, a more preferable range of the angle α1 is not less than 60 ° and not more than 90 °. The angle α1 in this embodiment is 85 °. In addition, when the 1st connection part 54 is a curved surface, angle (alpha) 1 is prescribed | regulated by the angle which the tangent drawn | pulled from the outer peripheral end of the 2nd cutting edge 52 to the 1st connection part 54, and the 2nd cutting edge 52 makes.
Similarly, the angle α2 formed by the third cutting edge 53 and the second connecting portion 55 connected to the outer peripheral end of the third cutting edge 53 is not less than 60 ° and not more than 120 °. A more preferable range of the angle α2 is 60 ° or more and 90 ° or less. The angle α2 in this embodiment is 85 °. The method for defining the angle α2 when the second connecting portion 55 is a curved surface is the same as the angle α1.
When the angle α1 and the angle α2 are in the above-described range, the chip cutting performance is improved as compared with the case of an angle outside the range.
The first connecting portion 54 and the second connecting portion 55 have a concave curve shape that is recessed inward (center axis side) of the drilling tool 100. If these two connecting portions are concave, the connecting portion functions as a chip guide immediately after generation, and the chips curl along the connecting portion. For this reason, it becomes a chip with a smaller volume.
While the third cutting edge 53 is linear, a part of the first cutting edge 51 and the second cutting edge 52 is concavely curved rearward in the tool rotation direction K. By forming the first cutting edge 51 and the second cutting edge 52 in such a shape, the chips are concavely curved, so that they are easily broken when force is applied to the chips.

The drilling tool 100 includes a first cutting edge 51, a second cutting edge 52, and a third cutting edge 53 that are divided and arranged in steps of each other, and a first for moving chips flowing out from each cutting edge. The groove portion 21, the second groove portion 22 and the third groove portion are respectively formed in a spiral shape. Furthermore, the angle α1 formed by the second cutting edge 52 and the first connecting portion 54 and the angle α2 formed by the third cutting edge 53 and the second connecting portion 55 are 60 ° or more and 120 ° or less. By providing these shapes at the same time, chips are easily subdivided, and the drilling tool 100 can be processed with higher feed.

As mentioned above, although one embodiment was described as an example about the present invention, the present invention is not limited to the above-mentioned embodiment. For example, in the above embodiment, each of the substantially step-like tolerance ridge lines has two stepped portions and three divided cutting edges, but the number of stepped portions is not limited and is one. There may be three or more. In addition, the cutting edge of the above embodiment has a positional relationship such that the cutting edge located on the outer peripheral side of the drilling tool is retracted in the direction opposite to the tool rotation direction K, but conversely, the one located on the outer peripheral side. The positional relationship may be such that it is located on the front side in the tool rotation direction K. That is, with reference to the above embodiment, the second cutting edge 52 is positioned on the front side in the tool rotation direction K with respect to the third cutting edge 53, and the first cutting edge 51 is positioned more than the second cutting edge 52. The positional relationship is such that is located on the front side in the tool rotation direction K.

In the embodiment in which the intersection ridge line portion between the chip discharge groove and the tip surface has two or more step portions, it is preferable that the step portion located on the outer peripheral side of the drilling tool has a larger step size. With such a shape, chips generated from each cutting edge are smoothly curled.

Further, in the case of an embodiment in which the intersecting ridge line portion between the chip discharge groove and the tip surface has two or more stepped portions and three or more cutting edges, the cutting edge on the most central side of the drilling tool is excluded. Regarding the other cutting edges, it is preferable that the cutting edge located on the outer peripheral side is longer. In other words, the first cutting edge 51 is preferably longer than the second cutting edge 52 when described with reference to the above embodiment. At this time, the third cutting edge 53 need not be shorter than the second cutting edge 52. With such a shape, it is possible to shorten the width of the chip flowing out from the tool center side where the curl radius of the chip tends to increase. Thus, the chip can be curled to an appropriate size with a smaller restraining force.

Further, it is preferable that the angle formed by the tip portion of the chip discharge groove 20 and the tip surface 40 which is a flank, so-called vertical cutter angle, is as small as that corresponding to a cutting blade located far from the center of the drilling tool. For example, with reference to the above embodiment, the angle θ1 formed by the tip of the third groove portion 23 and the first flank 41> the tip of the second groove portion 22 and the first flank 41 It is preferable to satisfy an angle θ2 formed by the following: an angle θ3 formed by the tip of the first groove portion 21 and the second flank 42. With such a shape, it is possible to give strength to the cutting edge on the center side that requires higher cutting edge strength, and to give sharpness to the cutting edge on the outer peripheral side that requires sharpness rather than strength.

DESCRIPTION OF SYMBOLS 12 ... Margin 13 ... Outlet 20 ... Chip discharge groove 21 ... 1st groove part 22 ... 2nd groove part 23 ... 3rd groove part 40 ... Tip surface (flank)
41 ... 1st flank 42 ... 2nd flank 50 ... Intersection ridgeline part 51 of a chip discharge groove and a tip surface ... 1st cutting edge 52 ... 2nd cutting edge 53 ... 3rd cutting edge 54 ... 1st Connecting part 55 ... Second connecting part 100 ... Drilling tool

Claims (11)

A substantially cylindrical drilling tool (100),
A chip discharge groove (20) on the outer periphery;
A tip surface (40),
The intersecting ridge line portion (50) between the tip surface (40) and the chip discharge groove (20) is stepped,
The chip discharging groove (20) is a drilling tool (100) having a spiral shape. The intersecting ridge line part (50) is a part involved in cutting, and has a plurality of action parts (51, 52, 53) arranged in steps with each other, and a part connecting the action parts (51, 52, 53) to each other. When the connection portion (54, 55) is formed, the arbitrary action portion (52, 53) and the connection portion (54, 55) connected to the outer end of the action portion (52, 53) are formed. The drilling tool (100) according to claim 1, wherein the angle is not less than 60 ° and not more than 120 °. The drilling tool (100) according to claim 2, wherein an angle formed by the action portion (52, 53) and the connecting portion (54, 55) is 60 ° or more and 90 ° or less. The drilling tool (100) according to claims 1 to 3, wherein the twist angle of the chip discharge groove (20) is 40 ° or less. The drilling tool (100) according to claim 4, wherein a twist angle of the chip discharge groove (20) is not less than 20 ° and not more than 35 °. The drilling tool (100) according to any one of claims 2 to 5, wherein the connecting portion (54, 55) has a concave curve shape recessed inward. The drilling tool (100) according to any one of claims 2 to 6, wherein at least a part of the action portion (51, 52, 53) is concavely curved rearward in the tool rotation direction. The drilling tool (100) according to any one of claims 2 to 7, wherein a size of each step formed by the action portions (51, 52, 53) increases as a step located on the outer peripheral side. . There are three or more working parts,
The length of each action part (51, 52) other than the action part (53) in the most central side among the action parts (51, 52, 53) becomes longer as it is located on the outer peripheral side. Drilling tool (100) according to any one of 2 to 8. The drilling tool (100) according to any one of claims 1 to 9, wherein a clearance angle at an outer peripheral end of the intersecting ridge portion (50) is greater than 0 ° and equal to or less than 15 °. The angle formed between the tip of the chip discharge groove (20) and the tip surface (40) corresponds to the action part (51, 52, 53) located far from the center of the drilling tool (100). Drilling tool (100) according to claims 2 to 10, which is so small.

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