Indexable drill with improved coolant injection structure

Abstract

The present invention relates to an indexable drill with an improved cutting fluid injection structure in which a cutting fluid discharge hole is formed on the thinning surface of a holder so that cutting fluid is directly sprayed onto the main cutting edge of an insert during a cutting process. In the indexable drill, a first head portion (12) and a second head portion (14) are formed at the tip of a holder (10), a mounting groove (11) is arranged between the first head portion (12) and the second head portion (14), an insert (20) is fitted into the mounting groove (11), and a bolt (30) is fastened to a fastening hole (15) of the second head portion (14) through a bolt hole (13) of the first head portion (11) and a bolt hole (23) of the insert (20) so that a bolt (30) can vertically penetrate the insert (20). In this indexable drill, the first head portion (12) and the second head portion (14) are symmetrically arranged with respect to each other with respect to the insert (20). A first coolant injection hole (110) is formed on the relief surface (12a) of the first head part (12), the first coolant injection hole (110) is positioned close to the outer circumference of the first head part (12), a second coolant injection hole (120) is formed on the thinning surface (12b) of the first head part (12), the second coolant injection hole (120) is drilled so that the insert (20) faces the main cutting edge, and the second coolant injection hole (120) is positioned close to the first side wall part (11-1) of the mounting groove (11), so that coolant is directly injected from the second coolant injection hole (120) to the main cutting edge of the insert (20), a third coolant injection hole (150) is formed on the relief surface (14a) of the second head part (14), and the third coolant The injection hole (150) is positioned close to the outer periphery of the second head portion (14), the fourth cutting fluid injection hole (160) is formed on the thinning surface (14b) of the second head portion (14), the fourth cutting fluid injection hole (160) is drilled so as to face the main cutting edge of the insert (20), and the fourth cutting fluid injection hole (160) is positioned close to the second side wall portion (11-2) of the mounting groove (11), so that cutting fluid is directly injected from the fourth cutting fluid injection hole (160) to the main cutting edge of the insert (20).

Description

Technology Field

[0001] The present invention relates to an indexable drill with an improved cutting fluid injection structure in which a cutting fluid discharge hole is formed on the thinning surface of a holder so that the cutting fluid is directly injected onto the main cutting edge of an insert during the cutting process. More specifically, the cutting fluid injection hole is formed on the thinning surface of a head portion and is drilled so as to face the insert. By directly injecting the cutting fluid from the cutting fluid injection hole onto the main cutting edge of the insert, the invention prevents heat from being generated in the insert during the drilling process of the workpiece, thereby preventing the formation of spherical cutting edges caused by heat and friction, and preventing wear of the main cutting edge of the insert. Background Technology

[0003] An "indexable drill" is introduced in Korean Patent Publication No. 10-2011-0139444.

[0004] The indexable drill described above has a pair of flute grooves formed in the drill body, a mounting groove formed between a pair of head portions of the drill body into which an insert is fitted, and an insert and a pair of head portions formed symmetrically with respect to a center. In this indexable drill, a flute groove is formed in a narrow width in the head portion and body portion of the drill body as a first step, thereby securing a drilling area portion on the outer circumferential side of the head portion, and a bolt hole is drilled in the drilling area portion, and the bolt hole intersects perpendicularly with the center line of the insert so that a bolt is fitted into the bolt hole of one head portion and fastened to the bolt hole of the opposite head portion through a hole formed in the center of the body portion of the insert, and so that chip evacuation can be smoothly achieved, a double thinning surface is formed on the lower part of the thinning surface of the head portion, and milling is started from the flute groove in line with the bottom surface of the mounting groove, thereby forming the flute groove as a second step, so that the flute groove has an increased groove width, and a concave portion is formed on the lower part of the double thinning surface.

[0005] However, the above-mentioned enducible drill has a disadvantage in that the cutting fluid discharge hole is formed on the relief surface and is positioned close to the outer surface of the relief surface, so the cutting fluid is not sprayed directly from the cutting fluid discharge hole to the main cutting edge of the insert, and as shown in Fig. 1, the center of the chip is burned black due to heat, friction, etc., and a spherical cutting edge is formed, resulting in poor surface roughness of the cutting surface and a short tool life in which the main cutting edge of the insert is easily worn out. The problem to be solved

[0007] Accordingly, the objective of the present invention is to provide an indexable drill with an improved cutting fluid injection structure, wherein a cutting fluid injection hole is formed on the thinning surface of the head portion, the cutting fluid injection hole is drilled so as to face the main cutting edge of the insert, and the cutting fluid injection hole is positioned close to the side wall of the mounting groove, so that the cutting fluid is directly injected from the cutting fluid injection hole to the main cutting edge of the insert. This prevents heat from being generated in the insert during the cutting process of the workpiece, thereby preventing the formation of a spherical cutting edge and preventing wear of the main cutting edge of the insert.

[0008] Another objective of the present invention is to provide an indexable drill with an improved cutting fluid injection structure, wherein a cooling hole is formed in the side wall of a mounting groove, a connecting passage is formed on the periphery of the lower receiving portion of the mounting groove into which the shank of an insert is fitted, the lower end of the connecting passage is connected to a discharge hole, and the upper end of the connecting passage is connected to a cooling hole, so that cutting fluid is supplied to the cooling hole through the connecting passage, and the cutting fluid comes into contact with the insert and cools the insert as it passes through the connecting passage and the cooling hole, thereby preventing heat generation in the insert during the process of drilling a workpiece, thus preventing the formation of a spherical edge on the main cutting edge and preventing wear of the main cutting edge of the insert. means of solving the problem

[0010] An example of an indexable drill with an improved cutting fluid injection structure according to the present invention for achieving the above-mentioned purpose is,

[0011] An indexable drill having a first head portion and a second head portion formed at the tip of a holder, a mounting groove disposed between the first head portion and the second head portion, an insert fitted into the mounting groove, and a bolt fastened to a fastening hole of the second head portion through a bolt hole of the first head portion and a bolt hole of the insert so that the bolt can vertically penetrate the insert,

[0012] A first head part and a second head part are arranged symmetrically with respect to each other with respect to an insert, a first coolant injection hole is formed on the relief surface of the first head part, the first coolant injection hole is arranged close to the outer periphery of the first head part, a second coolant injection hole is formed on the thinning surface of the first head part, the second coolant injection hole is drilled so as to face the main cutting edge of the insert, and the second coolant injection hole is arranged close to the first side wall of the mounting groove so that coolant is directly injected from the second coolant injection hole to the main cutting edge of the insert, a third coolant injection hole is formed on the relief surface of the second head part, the third coolant injection hole is arranged close to the outer periphery of the second head part, a fourth coolant injection hole is formed on the thinning surface of the second head part, the fourth coolant injection hole is drilled so as to face the main cutting edge of the insert, and the fourth coolant injection hole is arranged close to the second side wall of the mounting groove, It is characterized by the cutting fluid being sprayed directly from the fourth cutting fluid injection hole to the main cutting edge of the insert.

[0013] In addition, the indexable drill with an improved cutting fluid injection structure according to the present invention has a main cutting fluid supply hole formed longitudinally in the center of a holder, a first cutting fluid injection hole branched from the main cutting fluid supply hole so that cutting fluid is injected through the first cutting fluid injection hole, a second cutting fluid injection hole branched from the first cutting fluid injection hole so that cutting fluid is injected through the second cutting fluid injection hole, a first cooling hole formed on the first side wall of a mounting groove, a first connecting passage formed on the periphery of the lower receiving portion of the mounting groove into which the shank of an insert is fitted, the lower end of the first connecting passage is connected to a first discharge hole, and the upper end of the first connecting passage is connected to a first cooling hole, so that cutting fluid is supplied from the lower end of the first discharge hole to the first cooling hole through the first connecting passage and is discharged from the first cooling hole to the upper end of the first discharge hole, and in the process of the cutting fluid passing through the first connecting passage and the first cooling hole It is characterized by cooling the insert by coming into contact with it.

[0014] In addition, the indexable drill with an improved cutting fluid injection structure according to the present invention is characterized in that a third cutting fluid injection hole branches off from the main cutting fluid supply hole of the holder, thereby injecting cutting fluid through the third cutting fluid injection hole, a fourth cutting fluid injection hole branches off from the third cutting fluid injection hole, thereby injecting cutting fluid through the fourth cutting fluid injection hole, a second cooling hole is formed on the second side wall of the mounting groove, a second connecting passage is formed on the periphery of the lower receiving portion of the mounting groove into which the shank of the insert is fitted, the lower end of the second connecting passage is connected to a second discharge hole, and the upper end of the second connecting passage is connected to a second cooling hole, so that cutting fluid is supplied from the lower end of the third discharge hole to the second cooling hole through the second connecting passage, and is discharged from the second cooling hole to the upper end of the third discharge hole, and the cutting fluid comes into contact with the insert and cools the insert as it passes through the second connecting passage and the second cooling hole. does.

[0015] The first cooling hole is formed on the side of the bolt hole formed in the first head and is characterized by being partially open to communicate with the bolt hole.

[0016] The second cooling hole is formed on the side of the fastening hole formed in the second head, and is characterized by being partially open to communicate with the fastening hole.

[0017] In addition, the indexable drill with an improved cutting fluid injection structure according to the present invention is characterized in that when an insert is mounted in a mounting groove and the shank portion of the insert is placed in the lower receiving portion of the mounting groove, a chamber is formed between the bottom surface of the lower receiving portion and the shank portion, and the chamber communicates with the lower end of the first and second connecting passages, so that cutting fluid supplied from the main cutting fluid supply hole to the chamber comes into contact with the shank portion of the insert to cool the shank portion, and the cutting fluid supplied to the chamber is provided to the first and second connecting passages.

[0018] In addition, the indexable drill with an improved cutting fluid injection structure according to the present invention is characterized in that an auxiliary cutting fluid discharge hole is formed at the beginning of a pair of flute grooves formed in the holder, and the auxiliary cutting fluid discharge hole is drilled parallel to the centerline of the holder, so that during the process of drilling a workpiece, the auxiliary cutting fluid discharge hole does not affect the discharge of cutting chips, and the cutting fluid discharged through the auxiliary cutting fluid discharge hole is directly ejected to the main cutting edge of the insert.

[0019] Another example of an indexable drill with an improved cutting fluid injection structure according to the present invention is,

[0020] An indexable drill having a first head portion and a second head portion formed at the tip of a holder, a mounting groove disposed between the first head portion and the second head portion, an insert fitted into the mounting groove, and a bolt fastened to a fastening hole of the second head portion through a bolt hole of the first head portion and a bolt hole of the insert so that the bolt can vertically penetrate the insert,

[0021] A first head part and a second head part are arranged symmetrically with respect to each other with respect to the insert, a first coolant discharge hole is formed on the relief surface of the first head part, the first coolant discharge hole is arranged to be in contact with the outer periphery of the first head part, a second coolant discharge hole is formed extending from the thinning surface to the double thinning surface of the first head part, and the second coolant discharge hole is formed in a semicircular shape so that the coolant contacts the insert as it passes through the second coolant discharge hole and cools the insert by a heat exchange method, and the second coolant discharge hole is formed in a semi-cylindrical shape on the side wall of the mounting groove, and the second coolant discharge hole is formed in a straight line from the thinning surface and double thinning surface of the first head part to the first step part perpendicular to the bolt hole of the first head part, and the width diameter of the second coolant discharge hole is formed larger than the diameter of the bolt so that the coolant is not blocked by the bolt and is directly sprayed onto the main cutting edge of the insert through the second coolant discharge hole, and the second head part The third and fourth cutting fluid discharge holes formed are characterized by being configured identically to the first and second cutting fluid discharge holes.

[0022] In addition, the indexable drill with an improved cutting fluid injection structure according to the present invention is characterized by further including a cutting fluid discharge passage formed on the inner circumference of the lower receiving portion and drilled from the first step portion to the bottom surface of the lower receiving portion.

[0023] The above cutting fluid discharge passage is formed in a straight line vertically along the inner surface of the lower receiving portion and is formed in a semi-cylindrical shape, characterized in that the cutting fluid cools the shank of the insert as it passes through the cutting fluid discharge passage.

[0024] The first step portion is positioned at a depth deeper than the depth from the drill tip to the support surface supporting the insert, so that when the insert is mounted in the mounting groove, the discharge of cutting fluid by the insert is prevented. Effects of the invention

[0026] By this, the indexable drill with an improved cutting fluid injection structure according to the present invention can prevent heat from being generated in the insert during the workpiece cutting process, thereby preventing the occurrence of spherical cutting edges and preventing wear of the main cutting edge of the insert. Brief explanation of the drawing

[0028] Figure 1 is a photograph showing chips generated during the cutting process of a conventional indexable drill. FIG. 2 is a perspective view illustrating an indexable drill according to the present invention. FIG. 3 is an exploded perspective view showing an enlarged view of the main part of an indexable drill according to the present invention. FIG. 4 is a cross-sectional view along line AA of FIG. 2 illustrating an indexable drill according to the present invention. Figure 5 shows the insert separated from the mounting groove of the holder in the cross-sectional view of Figure 4. FIG. 6 is a plan view illustrating an indexable drill with an improved cutting fluid injection structure according to the first embodiment of the present invention. FIG. 7 is a cross-sectional view along line BB of FIG. 6 illustrating an indexable drill with an improved cutting fluid injection structure according to the first embodiment of the present invention, showing an enlarged view of the key parts. FIG. 8 is a cross-sectional view showing the state in which an insert is fitted into the mounting groove in FIG. 7. FIGS. 9 and 10 illustrate auxiliary coolant discharge holes formed in a pair of flute grooves in an indexable drill with an improved coolant injection structure according to the first embodiment of the present invention. FIG. 11 illustrates that when drilling a workpiece, cutting fluid is directly sprayed from the auxiliary cutting fluid discharge hole to the main cutting edge of the insert. FIG. 12 is a plan view illustrating an indexable drill with an improved cutting fluid injection structure according to a second embodiment of the present invention. FIG. 13 is an enlarged perspective view of the holder of an indexable drill with an improved cutting fluid injection structure according to a second embodiment of the present invention. FIG. 14 is a cross-sectional view along the CC line of FIG. 12 illustrating an indexable drill with an improved cutting fluid injection structure according to a second embodiment of the present invention. FIG. 15 is a cross-sectional view along line EE of FIG. 14 illustrating an indexable drill with an improved cutting fluid injection structure according to a second embodiment of the present invention. FIG. 16 is a cross-sectional view along line DD of FIG. 13 illustrating an indexable drill with an improved cutting fluid injection structure according to a second embodiment of the present invention. Specific details for implementing the invention

[0029] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

[0030] Referring to FIGS. 2 to 4, the indexable drill according to the present invention has a first head portion (12) and a second head portion (14) formed at the tip of a holder (10), a mounting groove (11) is arranged between the first head portion (12) and the second head portion (14), an insert (20) is fitted into the mounting groove (11), and a bolt (30) is fastened to the fastening hole (15) of the second head portion (14) through the bolt hole (13) of the first head portion (11) and the bolt hole (23) of the insert (20) so that the bolt (30) can vertically penetrate the insert (20).

[0031] Referring to FIG. 5, the mounting groove (11) includes an upper receiving portion (11a) in which the main body portion (21) of the insert (20) is placed, and a cylindrical lower receiving portion (11c) in which the handle portion (22) of the insert (20) is placed. The lower receiving portion (11c) is perforated downward from the support surface (11b) of the upper receiving portion (11a), the main body portion (21) of the insert (20) is caught on the support surface (11b) of the upper receiving portion (11a), and a main cutting fluid supply hole (40) is perforated in the bottom surface (11d) of the lower receiving portion (11c).

[0032] Referring to FIGS. 6 to 8, in an indexable drill as described above, the indexable drill with an improved cutting fluid injection structure according to the first embodiment of the present invention has a first head portion (12) and a second head portion (14) arranged symmetrically with respect to each other with respect to an insert (20), a first cutting fluid injection hole (110) is formed on the relief surface (12a) of the first head portion (12), the first cutting fluid injection hole (110) is arranged close to the outer circumference of the first head portion (12), a second cutting fluid injection hole (120) is formed on the thinning surface (12b) of the first head portion (12), the second cutting fluid injection hole (120) is drilled so as to face the main cutting edge of the insert (20), and the second cutting fluid injection hole (120) is formed on the first side wall portion (11-1) of the mounting groove (11; FIG. 7 (Reference) is positioned close to the second cutting fluid injection hole (120) so that cutting fluid is directly injected from the second cutting fluid injection hole (120) to the main cutting edge of the insert (20), a third cutting fluid injection hole (150) is formed on the relief surface (14a) of the second head part (14), the third cutting fluid injection hole (150) is positioned close to the outer circumference of the second head part (14), a fourth cutting fluid injection hole (160) is formed on the thinning surface (14b) of the second head part (14), the fourth cutting fluid injection hole (160) is perforated so as to face the main cutting edge of the insert (20), and the fourth cutting fluid injection hole (160) is positioned close to the second side wall part (11-2) of the mounting groove (11) so that cutting fluid is directly injected from the fourth cutting fluid injection hole (160) to the main cutting edge of the insert (20).

[0033] And, in an indexable drill with an improved cutting fluid injection structure according to the first embodiment of the present invention, a main cutting fluid supply hole (40) is formed in the longitudinal direction at the center of a holder (10), a first cutting fluid injection hole (110) branches off from the main cutting fluid supply hole (40) so that cutting fluid is injected through the first cutting fluid injection hole (110), a second cutting fluid injection hole (120) branches off from the first cutting fluid injection hole (110) so that cutting fluid is injected through the second cutting fluid injection hole (120), a first cooling hole (130) is formed on the first side wall portion (11-1) of a mounting groove (11), a first connecting passage (140) is formed on the periphery of the lower receiving portion (11c) of the mounting groove (11) into which the shank portion (22) of an insert (20) is fitted, and the lower end of the first connecting passage (140) is the first The upper end of the first connecting passage (140) is connected to the discharge hole (110), and the cutting fluid is supplied from the lower end of the first discharge hole (110) to the first cooling hole (130) through the first connecting passage (140), and is discharged from the first cooling hole (130) back to the upper end of the first discharge hole (110), and the cutting fluid comes into contact with the insert (20) as it passes through the first connecting passage (140) and the first cooling hole (130), thereby cooling the insert (20).

[0034] Additionally, a third cutting fluid injection hole (150) branches off from the main cutting fluid supply hole (40) of the holder (10), and cutting fluid is injected through the third cutting fluid injection hole (150), and a fourth cutting fluid injection hole (160) branches off from the third cutting fluid injection hole (150), and cutting fluid is injected through the fourth cutting fluid injection hole (160), and a second cooling hole (170) is formed in the second side wall portion (11-2) of the mounting groove (11), and a second connecting passage (180) is formed on the periphery of the lower receiving portion (11c) of the mounting groove (11) into which the shank portion (22) of the insert (20) is fitted, and the lower end of the second connecting passage (180) is connected to the second discharge hole (150), and the upper end of the second connecting passage (180) is connected to the second cooling hole (170). The cutting fluid is supplied from the lower part of the third discharge hole (150) to the second cooling hole (170) through the second connecting passage (180), and is discharged from the second cooling hole (170) back to the upper part of the third discharge hole (150), and as the cutting fluid passes through the second connecting passage (180) and the second cooling hole (170), it comes into contact with the insert (20) and cools the insert (20).

[0035] Referring to FIG. 9, the first cooling hole (130) is formed on the side of the bolt hole (13) formed in the first head (12) and is partially open to communicate with the bolt hole (13).

[0036] By this, the cutting fluid can cool the bolt (30), thereby preventing the bolt (30) from becoming loose or deformed due to heat. This is intended to prevent problems with the bolt caused by heat transferred from the insert (20) to the bolt (30).

[0037] Referring to FIG. 10, the second cooling hole (170) is formed on the side of the fastening hole (15) formed in the second head (14), and is partially open to communicate with the fastening hole (15).

[0038] By this, the cutting fluid can cool the bolt (30), thereby preventing the bolt (30) from becoming loose or deformed due to heat. This is intended to prevent problems with the bolt caused by heat transferred from the insert (20) to the bolt (30).

[0039] Referring again to FIGS. 7 and 8, the indexable drill with an improved cutting fluid injection structure according to the first embodiment of the present invention has an insert (20) mounted in a mounting groove (11; see FIG. 7) as shown in FIG. 8, and when the shank (22) of the insert (20) is placed in the lower receiving portion (11b; see FIG. 7) of the mounting groove (11), a chamber (190) is formed between the bottom surface (11d) of the lower receiving portion (11b) and the shank, and the chamber (190) communicates with the lower ends of the first and second connecting passages (140, 180), so that cutting fluid supplied from the main cutting fluid supply hole (40) to the chamber (190) comes into contact with the shank (22) of the insert (20) to cool the shank (22), and the cutting fluid supplied to the chamber (190) contacts the first and second connecting passages (140, It is provided as 180).

[0040] Referring to FIGS. 9 to 11, an indexable drill with an improved cutting fluid injection structure according to the first embodiment of the present invention has an auxiliary cutting fluid discharge hole (50, 55) formed at the beginning of a pair of flute grooves (17, 18) formed in a holder (10), and the auxiliary cutting fluid discharge hole (50, 55) is drilled parallel to the centerline (O1) of the holder (10), so that during the process of drilling a workpiece (60), the auxiliary cutting fluid discharge hole (50, 55) does not affect the discharge of cutting chips, and the cutting fluid discharged through the auxiliary cutting fluid discharge hole (50, 55) is directly ejected to the main cutting edge of the insert (20).

[0041] When drilling a hole in a workpiece, the indexable drill with an improved cutting fluid injection structure according to the first embodiment of the present invention as described above has a second cutting fluid injection hole (120) formed on the thinning surface (12b) of the head portion (12) and drilled so that the second cutting fluid injection hole (120) faces the main cutting edge of the insert (20), so that cutting fluid is directly injected from the second cutting fluid injection hole (120) to the main cutting edge of the insert (20), and a fourth cutting fluid injection hole (160) formed on the thinning surface (14b) of the second head portion (14) and drilled so that the fourth cutting fluid injection hole (160) faces the main cutting edge of the insert (20), so that cutting fluid is directly injected from the fourth cutting fluid injection hole (160) to the main cutting edge of the insert (20), thereby allowing the cutting fluid injected from the cutting fluid injection hole to directly reach the main cutting edge of the insert. By spraying, heat can be prevented from being generated in the insert (20) during the process of drilling the workpiece, thereby preventing the formation of a spherical cutting edge and preventing the main cutting edge of the insert from wearing out.

[0042] Additionally, cutting fluid is supplied from the lower part of the first discharge hole (110) to the first cooling hole (130) through the first connecting passage (140), and is discharged from the first cooling hole (130) back to the upper part of the first discharge hole (110), and as the cutting fluid passes through the first connecting passage (140) and the first cooling hole (130), it comes into contact with the insert (20) to cool the insert (20), and as the cutting fluid passes through the second connecting passage (180) from the lower part of the third discharge hole (150) to the second cooling hole (170), and is discharged from the second cooling hole (170) back to the upper part of the third discharge hole (150), and as the cutting fluid passes through the second connecting passage (180) and the second cooling hole (170), it comes into contact with the insert (20) to cool the insert (20). By cooling, the heat accumulated in the insert during the workpiece drilling process can be cooled, which has the advantage of preventing the insert from wearing out due to heat.

[0044] Referring to FIGS. 12 to 16, an indexable drill with an improved cutting fluid injection structure according to a second embodiment of the present invention, as shown in FIG. 12, has a first head portion (12) and a second head portion (14) arranged symmetrically with respect to each other with respect to an insert (20), a first cutting fluid discharge hole (210) formed on the relief surface (12a) of the first head portion (12), the first cutting fluid discharge hole (210) arranged to be in contact with the outer circumference of the first head portion (12), a second cutting fluid discharge hole (220) formed extending from the thinning surface (12b) to the double thinning surface (12c) of the first head portion (12), and the second cutting fluid discharge hole (220) formed in a semicircular shape, so that as the cutting fluid passes through the second cutting fluid discharge hole (220), it comes into contact with the insert (20) and heat exchanges in a manner The insert (20) is cooled, and as shown in FIGS. 13 and 14, a second coolant discharge hole (220) is formed in a semi-cylindrical shape on the side wall (11-1) of the mounting groove (11), and the second coolant discharge hole (220) is formed in a straight line from the thinning surface (12b) and double thinning surface (12c) of the first head part (12) to the first step portion (230) perpendicular to the bolt hole (13) of the first head part (12), and as shown in FIG. 15, the width diameter (d2) of the second coolant discharge hole (220) is formed to be larger than the diameter (d1) of the bolt (30), so that the coolant is not blocked by the bolt (30) and is directly sprayed to the main cutting edge of the insert (20) through the second coolant discharge hole (220), and the third and fourth formed on the second head part (14) The configuration of the cutting fluid discharge holes (250, 260) is configured in the same way as the first and second cutting fluid discharge holes (210, 220).

[0045] Referring to FIGS. 13, 14, and 16, the indexable drill with improved cutting fluid injection structure according to the first embodiment of the present invention further includes a cutting fluid discharge passage (240) formed on the inner circumference of the lower receiving portion (11c) and drilled from the first step portion (120) to the bottom surface (11d) of the lower receiving portion (11c).

[0046] The above cutting fluid discharge passage (240) is formed in a straight line vertically along the inner surface of the lower receiving portion (11c) and is formed in a semi-cylindrical shape, so that as the cutting fluid passes through the cutting fluid discharge passage (240), the handle portion (22) of the insert (20) is cooled.

[0047] As shown in FIG. 16, the first step portion (230) is positioned at a depth (h2) deeper than the depth (h1) from the drill tip (O) to the support surface (11b) supporting the insert (20; see FIG. 14), thereby preventing interference with the discharge of cutting fluid by the insert (20) when the insert (20) is mounted in the mounting groove (11).

[0048] At this time, the cutting fluid is supplied from the main cutting fluid supply hole (40) to the cutting fluid discharge passage (240), and from the cutting fluid discharge passage (240) to the second cutting fluid discharge hole (220), and is sprayed from the second cutting fluid discharge hole (220) to the main cutting edge of the insert (20).

[0049] As shown in FIG. 4, the indexable drill with an improved cutting fluid injection structure according to the second embodiment of the present invention configured as described above has a main cutting fluid supply hole (40) drilled into the bottom surface (11d) of the mounting groove (11), and the cutting fluid supplied through the main cutting fluid supply hole (40) is supplied to the space (11e) between the bottom surface (11d) of the mounting groove (11) and the shank (22) of the insert (20), and is supplied from the space (11e) to the cutting fluid discharge passage (240), and the cutting fluid supplied to the cutting fluid discharge passage (240) is sprayed onto the main cutting edge of the insert (20) through the second cutting fluid discharge hole (220) to cool the insert (20).

[0050] At this time, the width diameter (d1) of the second cutting fluid discharge hole (220) is formed to be larger than the diameter (d2) of the bolt (30), so that the cutting fluid is not blocked by the bolt (30) and is sprayed through the second cutting fluid discharge hole (220) to the main cutting edge of the insert (20), and the cutting fluid discharge passage (240) and the second cutting fluid discharge hole (220) are formed in a semi-cylindrical shape so that the cutting fluid comes into contact with the insert (20) as it passes through the cutting fluid discharge passage (240) and the second cutting fluid discharge hole (220), thereby cooling the insert (20) by a heat exchange method.

[0051] The indexable drill with an improved cutting fluid injection structure according to the second embodiment of the present invention as described above has the advantage of being able to directly spray cutting fluid onto the main cutting edge of the insert (20), thereby cooling the main cutting edge of the insert when drilling a workpiece, preventing cutting chips from burning black due to heat, preventing the formation of spherical cutting edges due to heat and friction, and preventing the main cutting edge of the insert (20) from wearing out due to heat and friction.

[0053] As described above, the present invention has been explained by specific details such as specific components, limited embodiments, and drawings; however, this is provided merely to aid in a more comprehensive understanding of the invention, and the invention is not limited to the above embodiments. A person skilled in the art can make various modifications and variations from this description.

[0054] Accordingly, the scope of the present invention is not limited to the described embodiments, and all things equivalent to or having equivalent variations to the claims set forth below, as well as the claims set forth below, shall be considered to fall within the scope of the concept of the present invention. Explanation of the symbols

[0056] 10 : Holder 11 : Mounting groove 12: 1st head section 14: 2nd head section 20 : Insert 30 : Bolt 110: 1st coolant spray hole 120: 2nd coolant spray hole 150: 3rd coolant spray hole 160: 4th coolant spray hole

Claims

Claim 1 In an indexable drill in which a first head portion (12) and a second head portion (14) are formed at the tip of a holder (10), a mounting groove (11) is disposed between the first head portion (12) and the second head portion (14), an insert (20) is fitted into the mounting groove (11), and a bolt (30) is fastened to a fastening hole (15) of the second head portion (14) through a bolt hole (13) of the first head portion (11) and a bolt hole (23) of the insert (20) so that the bolt (30) can vertically penetrate the insert (20), wherein the first head portion (12) and the second head portion (14) are arranged symmetrically with respect to each other with respect to the insert (20), a first cutting fluid injection hole (110) is formed on the relief surface (12a) of the first head portion (12), and the first cutting fluid A spray hole (110) is positioned close to the outer periphery of the first head portion (12), a second cutting fluid spray hole (120) is formed on the thinning surface (12b) of the first head portion (12), the second cutting fluid spray hole (120) is drilled so as to face the main cutting edge of the insert (20), and the second cutting fluid spray hole (120) is positioned close to the first side wall portion (11-1) of the mounting groove (11), so that cutting fluid is directly sprayed from the second cutting fluid spray hole (120) to the main cutting edge of the insert (20), a third cutting fluid spray hole (150) is formed on the relief surface (14a) of the second head portion (14), the third cutting fluid spray hole (150) is positioned close to the outer periphery of the second head portion (14), and a fourth cutting fluid spray hole (160) is the second A fourth coolant injection hole (160) is formed on the thinning surface (14b) of the head portion (14) and is perforated so as to face the main cutting edge of the insert (20), and the fourth coolant injection hole (160) is positioned close to the second side wall portion (11-2) of the mounting groove (11), so that coolant is directly injected from the fourth coolant injection hole (160) to the main cutting edge of the insert (20), and a main coolant supply hole (40) is formed in the longitudinal direction at the center of the holder (10), and a first coolant injection hole (110) branches off from the main coolant supply hole (40), so that coolant is injected through the first coolant injection hole (110).A second cutting fluid injection hole (120) branches off from a first cutting fluid injection hole (110), and cutting fluid is injected through the second cutting fluid injection hole (120). A first cooling hole (130) is formed on the first side wall portion (11-1) of the mounting groove (11), and a first connecting passage (140) is formed on the periphery of the lower receiving portion (11c) of the mounting groove (11) into which the shank portion (22) of the insert (20) is fitted. The lower end of the first connecting passage (140) is connected to the first discharge hole (110), and the upper end of the first connecting passage (140) is connected to the first cooling hole (130). Cutting fluid is supplied from the lower end of the first discharge hole (110) to the first cooling hole (130) through the first connecting passage (140), and from the first cooling hole (130) again An indexable drill characterized by the cutting fluid being discharged through the upper part of the first discharge hole (110) and coming into contact with the insert (20) to cool the insert (20) as it passes through the first connecting passage (140) and the first cooling hole (130). Claim 2 delete Claim 3 In claim 1, a third cutting fluid injection hole (150) branches off from the main cutting fluid supply hole (40) of the holder (10), and cutting fluid is injected through the third cutting fluid injection hole (150); a fourth cutting fluid injection hole (160) branches off from the third cutting fluid injection hole (150), and cutting fluid is injected through the fourth cutting fluid injection hole (160); a second cooling hole (170) is formed in the second side wall portion (11-2) of the mounting groove (11); a second connecting passage (180) is formed on the periphery of the lower receiving portion (11c) of the mounting groove (11) into which the shank portion (22) of the insert (20) is fitted; the lower end of the second connecting passage (180) is connected to the second discharge hole (150), and the upper end of the second connecting passage (180) is connected to the second cooling hole (170). An indexable drill characterized by being connected such that cutting fluid is supplied from the lower part of the third discharge hole (150) to the second cooling hole (170) through the second connecting passage (180), and is discharged from the second cooling hole (170) to the upper part of the third discharge hole (150), and the cutting fluid comes into contact with the insert (20) and cools the insert (20) as it passes through the second connecting passage (180) and the second cooling hole (170). Claim 4 An indexable drill according to claim 1, wherein the first cooling hole (130) is formed on the side of the bolt hole (13) formed in the first head (12) and is partially open to communicate with the bolt hole (13). Claim 5 In claim 3, the indexable drill is characterized in that the second cooling hole (170) is formed on the side of the fastening hole (15) formed in the second head (14) and is partially open to communicate with the fastening hole (15). Claim 6 An indexable drill according to claim 1, wherein an insert (20) is mounted in a mounting groove (11) and the shank portion (22) of the insert (20) is placed in the lower receiving portion (11b) of the mounting groove (11), a chamber (190) is formed between the bottom surface (11d) of the lower receiving portion (11b) and the shank portion, and the chamber (190) communicates with the lower ends of the first and second connecting passages (140, 180), so that cutting fluid supplied from the main cutting fluid supply hole (40) to the chamber (190) comes into contact with the shank portion (22) of the insert (20) to cool the shank portion (22), and the cutting fluid supplied to the chamber (190) is provided to the first and second connecting passages (140, 180). Claim 7 An indexable drill according to claim 1, wherein an auxiliary coolant discharge hole (50, 55) is formed at the beginning of a pair of flute grooves (17, 18) formed in the holder (10), and the auxiliary coolant discharge hole (50, 55) is drilled parallel to the centerline (O1) of the holder (10), so that during the process of drilling the workpiece (60), the auxiliary coolant discharge hole (50, 55) does not affect the discharge of cutting chips, and the coolant discharged through the auxiliary coolant discharge hole (50, 55) is directly ejected to the main cutting edge of the insert (20). Claim 8 In an indexable drill in which a first head portion (12) and a second head portion (14) are formed at the tip of a holder (10), a mounting groove (11) is disposed between the first head portion (12) and the second head portion (14), an insert (20) is fitted into the mounting groove (11), and a bolt (30) is fastened to a fastening hole (15) of the second head portion (14) through a bolt hole (13) of the first head portion (11) and a bolt hole (23) of the insert (20) so that the bolt (30) can vertically penetrate the insert (20), wherein the first head portion (12) and the second head portion (14) are arranged symmetrically with respect to each other with respect to the insert (20), a first cutting fluid discharge hole (210) is formed on the relief surface (12a) of the first head portion (12), and the first cutting fluid A discharge hole (210) is positioned to be in contact with the outer periphery of the first head portion (12), and a second coolant discharge hole (220) is formed extending from the thinning surface (12b) to the double thinning surface (12c) of the first head portion (12). The second coolant discharge hole (220) is formed in a semicircular shape so that as the coolant passes through the second coolant discharge hole (220), it comes into contact with the insert (20) and cools the insert (20) by a heat exchange method. Additionally, the second coolant discharge hole (220) is formed in a semi-cylindrical shape on the side wall portion (11-1) of the mounting groove (11), so that the second coolant discharge hole (220) extends perpendicularly to the bolt hole (13) of the first head portion (12) from the thinning surface (12b) and the double thinning surface (12c) of the first head portion (12) to the first step portion (230). An indexable drill characterized by being formed in a straight line, with the width diameter (d2) of the second coolant discharge hole (220) being larger than the diameter (d1) of the bolt (30), so that the coolant is not blocked by the bolt (30) and is directly injected into the insert (20) through the second coolant discharge hole (220), and the configuration of the third and fourth coolant discharge holes (250, 260) formed in the second head part (14) being the same as the first and second coolant discharge holes (210, 220). Claim 9 An indexable drill according to claim 8, further comprising a cutting fluid discharge passage (240) formed on the inner circumference of the lower receiving portion (11c) and drilled from the first step portion (120) to the bottom surface (11d) of the lower receiving portion (11c). Claim 10 In claim 9, the cutting fluid discharge passage (240) is formed in a straight line vertically along the inner surface of the lower receiving portion (11c) and is formed in a semi-cylindrical shape, so that the cutting fluid cools the shank portion (22) of the insert (20) as it passes through the cutting fluid discharge passage (240), characterized in that it is an indexable drill. Claim 11 An indexable drill according to claim 8, wherein the first step portion (230) is positioned at a depth (h2) deeper than the depth (h1) from the drill tip (O) to the support surface (11b) supporting the insert (20), thereby preventing interference with the discharge of cutting fluid by the insert (20) when the insert (20) is mounted in the mounting groove (11).

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