rotary cutting tools

Abstract

To provide a rotary cutting tool which reduces the size of swarfs.SOLUTION: A rotary cutting tool includes: a base metal 10 serving as a tool body which extends in an axial direction and is provided with a coolant supply hole having a portion extending in the axial direction therein; and a chip 11 provided at a tip of the base metal 10 and having a cutting blade made of a superhard tool material. The base metal 10 is provided with a discharge port 21 serving as an outlet of the coolant supply hole. A groove 22 is continuously provided from the discharge port 21 to a border between the chip 11 and the base metal 10.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to rotary cutting tools. [Background technology]

[0002] Conventional rotary cutting tools are disclosed, for example, in Japanese Utility Model Application Laid-Open Publication No. 58-44135 (Patent Document 1), Japanese Utility Model Application Laid-Open Publication No. 5-12039 (Patent Document 2), and Japanese Patent Laid-Open Publication No. 2010-94766 (Patent Document 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 58-44135 [Patent Document 2] Japanese Utility Model Application Publication No. 5-12039 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-94766 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional rotary cutting tools have the problem of producing long chips. [Means for solving the problem]

[0005] The present disclosure relates to a rotary cutting tool comprising a tool body extending in an axial direction and having a coolant supply hole therein with an axially extending portion, and a tip provided at the tip of the tool body and having a cutting edge made of an ultra-hard tool material, the tool body being provided with an outlet that serves as an exit for the coolant supply hole, and a continuous groove provided from the outlet to the boundary between the tip and the tool body. [Brief explanation of the drawings]

[0006] [Figure 1]FIG. 1 is a perspective view of a four-blade rotary cutting tool according to a first embodiment. [Figure 2] FIG. 2 is a plan view of the four-blade rotary cutting tool as seen from the direction indicated by arrow II in FIG. [Figure 3] FIG. 3 is a plan view of a single-blade rotary cutting tool according to a second embodiment. [Figure 4] FIG. 4 is a side view of the single-blade rotary cutting tool as seen from the direction indicated by arrow IV in FIG. [Figure 5] FIG. 5 is a plan view of a single-blade rotary cutting tool without grooves 22 according to Comparative Example 1. As shown in FIG. [Figure 6] FIG. 6 is a side view of the single-blade rotary cutting tool as seen from the direction indicated by arrow VI in FIG. [Figure 7] FIG. 7 is a plan view of a single-blade rotary cutting tool provided with short flutes 22 according to Comparative Example 2. As shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0007] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described.

[0008] The present disclosure relates to a rotary cutting tool comprising a tool body extending in an axial direction and having a coolant supply hole therein with an axially extending portion, and a tip provided at the tip of the tool body and having a cutting edge made of an ultra-hard tool material, the tool body being provided with an outlet that serves as an exit for the coolant supply hole, and a continuous groove provided from the outlet to the boundary between the tip and the tool body.

[0009] In the rotary cutting tool configured in this way, a continuous groove is provided from the outlet to the boundary between the tip and the tool body, allowing the coolant to be smoothly supplied from the outlet to the tip via this groove, thereby ensuring that the coolant can cool and lubricate the tip.

[0010] More specifically, it is generally known that the fluid discharged into the air from the outlet radially widens and its flow velocity gradually decreases as it moves away from the outlet. This rule also applies to internal coolant, so the coolant discharged from the outlet spreads radially before reaching the cutting edge. The grooves described above reduce the spread of the coolant, allowing the coolant to maintain its momentum and collide with the chips generated near the cutting edge. It is believed that this impact force reduces the shear angle of the chips, causing them to break down into smaller pieces.

[0011] Preferably, the groove depth is 0.1 mm or more and 1 / 2 the diameter of the coolant supply hole near the outlet. If the groove depth is 0.1 mm or more, the groove's effectiveness in guiding the coolant is enhanced. If the groove depth is 1 / 2 the diameter of the coolant supply hole or less, the groove will have an appropriate depth and will be effective in guiding the coolant.

[0012] (Embodiment 1) Fig. 1 is a perspective view of a four-flute rotary cutting tool according to embodiment 1. Fig. 2 is a plan view of the four-flute rotary cutting tool as viewed from the direction indicated by arrow II in Fig. 1.

[0013] As shown in Figures 1 and 2, a reamer 1 as a rotary cutting tool has a base metal 10 as a tool body. Figures 1 and 2 show the tip of the reamer 1. The base metal 10 is made of, for example, cemented carbide, steel (including stainless steel), or the like.

[0014] The base metal 10 is provided with four tips 11, 12, 13, and 14. A cutting edge is provided on each of the tips 11, 12, 13, and 14. Each of the tips 11, 12, 13, and 14 is made of an ultra-hard tool material such as cemented carbide, diamond, or cubic boron nitride.

[0015] The base metal 10 has a first surface (shank wall surface) 15 and a second surface (shank rake surface) 16 extending in the longitudinal direction. The first surface 15 and the second surface 16 form flutes extending in the longitudinal direction. The tip 11 is embedded in the second surface 16.

[0016] An outlet 21 for discharging the coolant is provided on the first surface 15. The outlet 21 is connected to a coolant supply hole (not shown) that extends through the base metal 10. As a result, the coolant supplied from the coolant supply hole is discharged from the outlet 21.

[0017] Groove 22 is provided continuously from discharge port 21 to the boundary between tip 11 and base metal 10. Groove 22 extends linearly in this drawing, but it may also extend in a curved line. The depth of groove 22 may be uniform or non-uniform.

[0018] The grooves 22 may or may not be provided near the other tips 12, 13, and 14 to supply coolant to these tips 12, 13, and 14. In other words, the grooves 22 may be provided only in some of the tips 11, 12, 13, and 14.

[0019] The four chips 11, 12, 13, and 14 may be arranged so as to divide the outer circumferential surface of the base metal 10 at equal angles, or may be arranged so as to divide the outer circumferential surface of the base metal 10 at unequal angles.

[0020] (Embodiment 2) Fig. 3 is a plan view of a single-blade rotary cutting tool according to embodiment 2. Fig. 4 is a side view of the single-blade rotary cutting tool as viewed from the direction indicated by arrow IV in Fig. 3 .

[0021] 3 and 4, the reamer 1 according to the second embodiment is a single-blade reamer 1. Only one tip 11 is provided on the outer periphery of the reamer 1. Note that the number of tips 11 on one reamer 1 may be more than one.

[0022] Branch holes 24 extend obliquely from a hole 23 extending in the longitudinal direction of the reamer 1. The hole 23 and the branch holes 24 form a coolant supply hole. The outlet opening of the branch hole 24 is the discharge port 21. The discharge port 21 has an elliptical shape. A groove 22 is provided continuously from the discharge port 21 to the boundary between the tip 11 and the base metal 10.

[0023] The depth of the groove 22 is 0.1 mm or more and 1 / 2 or less of the diameter of the branch hole 24 near the outlet 21. This diameter refers to the diameter of the branch hole 24 in a direction perpendicular to the direction in which the branch hole 24 extends.

[0024] The reamer 1 according to the second embodiment configured in this manner also has the same effects as the reamer 1 of the first embodiment.

[0025] (Comparative Example 1) Fig. 5 is a plan view of a single-blade rotary cutting tool according to Comparative Example 1, which is not provided with grooves 22. Fig. 6 is a side view of the single-blade rotary cutting tool as viewed from the direction indicated by arrow VI in Fig. 5.

[0026] As shown in FIGS. 5 and 6, the reamer of Comparative Example 1 differs from the reamers 1 of the first and second embodiments in that no groove is provided between the discharge port 21 and the tip 11.

[0027] (Comparative Example 2) Fig. 7 is a plan view of a single-blade rotary cutting tool provided with short flutes 22 according to Comparative Example 2. As shown in Fig. 7, the reamer 1 according to Comparative Example 2 is provided with flutes 22. The reamer 1 according to Comparative Example 2 differs from the reamers 1 according to the first and second embodiments in that the flutes 22 are connected to the tip 11 but are not connected to the discharge port 21.

[0028] [Details of the embodiments of the present disclosure] First, reamers with sample numbers 1-9, 101 and 102 shown in Table 1 were prepared.

[0029] [Table 1]

[0030] "Hole diameter D" in the table refers to the diameter D of the branch hole 24 shown in Figures 3, 5, and 7. "Groove depth" refers to the depth of the groove 22 measured from the surface of the second face 16. When the depth of the groove 22 is not uniform, the depth of the deepest part of the groove 22 is taken as the "groove depth."

[0031] Using this reamer, a machining test was carried out in which a pilot hole with an inner diameter of 20 mm was reamed to make the inner diameter 21 mm. The machining conditions were as follows:

[0032] Tip material: Polycrystalline diamond Base material: cemented carbide Tool diameter: 21mm Tool protrusion length L: 70 mm Workpiece material: ADC12 (aluminum die-cast) Dimensions and shape of pilot hole: Inner diameter 20 mm Number of processing: 5 Circumferential speed: 200m / min Feed (mm / rev): 0.15 Rotation speed: 3700 min -1 Processing depth: 30mm through hole Equipment: Vertical machining center (spindle BT30) Cutting oil: Emulsion-based water-soluble coolant, diluted 8% Cutting oil supply pressure: 1.2MPa After machining, the size of the chips was investigated, and the results are shown in Table 1. The longest chip was selected from the multiple chips generated during cutting, and the longest part of the curled chip was taken as the chip length.

[0033] From Table 1, it was found that the chip size was small in sample numbers 1 to 9, in which the grooves 22 were provided continuously from the tip 11 to the discharge port 21, as shown in Figures 3 and 4. In contrast, it was found that the chip size was large in sample numbers 101 and 102, in which the grooves 22 were not provided or the grooves 22 were not continuous from the tip 11 to the discharge port 21 and did not reach the discharge port 21.

[0034] It was found that chips can be broken down further if the depth of the grooves 22 is 0.1 mm or more and less than half the diameter of the branch holes 24 serving as coolant supply holes near the outlet. Even ductile materials such as aluminum alloys can be broken down into smaller chips.

[0035] It has been confirmed that the same effect can be obtained not only with reamers but also with other rotary cutting tools such as drills and end mills.

[0036] Furthermore, it can be manufactured at a lower cost than chip breakers for breaking up chips.Furthermore, the cutting edge damage and roughness of the machined surface caused by chip adhesion to the breaker recess, which are common with rotary cutting tools with breakers, were not observed.

[0037] The embodiments and examples disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0038] 1 reamer, 10 base metal, 11, 12, 13, 14 tips, 15 first surface, 16 second surface, 21 outlet, 22 groove, 23 hole, 24 branch hole.

Claims

1. a tool body extending in an axial direction and having a coolant supply hole formed therein, the coolant supply hole having a portion extending in the axial direction; a tip provided at the tip of the tool body and having a cutting edge made of an ultra-hard tool material; The tool body is provided with a discharge port serving as an outlet for the coolant supply hole, a groove is provided continuously from the discharge port to the boundary between the tip and the tool body, the groove being connected to the rake face of the tip.

2. 2. The rotary cutting tool according to claim 1, wherein the depth of the groove is 0.1 mm or more and 1 / 2 or less of the diameter of the coolant supply hole near the outlet.

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