Indexable drill

Abstract

The present invention provides an indexable drill bit, wherein the cutting insert includes: a cutting insert fastening surface that contacts and is fastened to a tool holder; a cutting insert placement surface that contacts and is placed on the tool holder; a cutting insert through-hole formed on the cutting insert fastening surface and for a first fastening bolt to pass through in the horizontal direction; and a reinforcement portion having a reinforcement portion groove having a first plane that forms a predetermined angle relative to the axial direction of the tool holder and protruding downward from the lower end of the cutting insert. In addition, the tool holder includes: a first tool holder through-hole for fastening the first fastening bolt and extending horizontally from one side of the tool holder to the other; and a second fastening bolt through-hole located below the tool holder through-hole, extending only from one side of the tool holder, and having an internal thread.

Description

Technical Field

[0001] The present invention relates to an indexable drill having replaceable cutting inserts. Background Art

[0002] A drill is a tool used to create holes in workpieces. As the drill's cutting edge wears, its cutting performance degrades, leading to the inconvenience of having to regrind it. To address this inconvenience, indexable drills, which allow the cutting inserts to be replaced and mounted in a tool holder, have been developed and are now widely used.

[0003] Figures 11 to 13 2 shows an example of an indexable drill 100 disclosed in Korean Utility Model Publication No. 20-0383648.

[0004] Such a conventional drill 100 includes a drill body 120 and a replaceable blade 140 .

[0005] In the conventional drill bit 100, the drill bit body 120 has screw insertion holes 127a, 127b, and the blade 140 has a screw fixing hole 143, which is penetrated by the fixing screw 130 for fixing. However, since the fixing screw 130 is simply in the horizontal direction (in the direction of the screw hole 143), the drill bit body 120 has screw insertion holes 127a, 127b, and the blade 140 has a screw fixing hole 143, which is penetrated by the fixing screw 130 for fixing. Figure 12 As a reference, the drill body 120 and the blade 140 are penetrated in the horizontal direction (with Figure 12 Therefore, during drilling, the blade vibrates relative to the drill body, and eventually, the drill body is frequently damaged due to chipping or breakage of the drill tip.

[0006] In addition, the oil holes 123a and 123b are formed only on the clearance surfaces 115a and 115b of the drill body 120. Figure 13 As shown, there is a problem that the cutting oil ejected from the oil holes 123a and 123b cannot flow toward the tip of the insert, and thus the wear resistance of the tip of the insert cannot be sufficiently improved.

[0007] For reference, Figures 11 to 13 Corresponding to the above Korean authorized utility model publications Figure 1 , Figure 5 a. Figure 5 b. For the sake of convenience in description, reference numerals are used as they are without modification. In addition, even if reference numerals identical to those used in the description of the present invention are used, they do not necessarily refer to identical components. Summary of the Invention

[0008] Technical issues

[0009] The present invention aims to solve the problems of the prior art as described above. The purpose of the present invention is to provide an indexable drill that can prevent chipping and breakage of the cutting insert by improving the wear resistance of the cutting insert and increasing the tightness between the tool holder and the cutting insert to prevent vibration during processing.

[0010] Technical Solution

[0011] To achieve the above-mentioned object, one embodiment of the present invention provides an indexable drill bit, comprising a replaceable cutting blade, a tool holder for mounting the cutting blade, and a first fastening bolt for fastening the cutting blade to the tool holder. The indexable drill bit is characterized in that the cutting blade comprises: a cutting blade fastening surface, which contacts and is fastened to the tool holder; a cutting blade placement surface, which contacts and is placed on the tool holder; a cutting blade through-hole, which is formed on the cutting blade fastening surface and is passed through by the first fastening bolt in the transverse direction; and a reinforcement portion. It has a plane forming a predetermined angle with respect to the axial direction of the tool holder and protruding downward from the lower end of the cutting blade. The tool holder includes: a first tool holder through-hole, which is used to tighten the first fastening bolt and penetrates horizontally from one side of the tool holder to the other side; and a second fastening bolt through-hole, which is located below the tool holder through-hole, penetrates only from one side of the tool holder, and is formed with an internal thread. The second fastening bolt is inserted into the second fastening bolt through-hole and contacts the plane of the reinforcement portion to apply a fastening force to the bottom of the central axis of the tool holder.

[0012] Furthermore, the position of the head of the first fastening bolt and the position of the head of the second fastening bolt are located on opposite sides with respect to the central axis of the tool holder.

[0013] Furthermore, a tip portion of the second fastening bolt is formed in a tapered shape, and the tip portion is in line contact with the plane surface of the reinforcement portion.

[0014] Furthermore, the reinforcement portion has a polygonal shape, the tool holder has a groove portion for inserting the reinforcement portion, and the groove portion has contact surfaces contacting two sides of the reinforcement portion facing each other to prevent the cutting insert from rotating relative to the tool holder.

[0015] Furthermore, in the cutting insert, the two cutting insert seating surfaces are provided 180° rotationally symmetrically with respect to the central axis of the cutting insert, and the extension lines of the cutting insert seating surfaces are V-shaped forming a predetermined angle.

[0016] Furthermore, a cutting oil supply groove is formed on the cutting insert fastening surface toward the tip end portion of the cutting insert.

[0017] Furthermore, the cutting oil supply groove is formed so that its width gradually decreases from a starting portion toward a terminal portion, so that a cross-sectional area decreases.

[0018] Furthermore, the tool holder includes a cutting oil supply pipe that leads to the tool holder clearance surface to form a cutting oil supply hole, and includes a branch pipe that branches in the middle and is connected to the cutting oil supply groove to communicate.

[0019] Furthermore, a terminal end portion of the cutting oil supply groove is located at a boundary between the clearance surface and the thinned surface of the cutting insert.

[0020] In addition, the diameter of the head of the first fastening bolt is larger than the diameter of the body, and the diameter of the head of the second fastening bolt is the same as the diameter of the body.

[0021] Effects of the Invention

[0022] The cutting insert according to the embodiment of the present invention having the above-described configuration has the following effects.

[0023] First, the second fastening bolt can be inserted into the second fastening bolt through hole and contact the flat surface of the reinforcement portion of the cutting insert to increase the fastening force in the downward direction of the central axis of the tool holder.

[0024] Furthermore, the through hole for the second fastening bolt may be formed in a direction opposite to the direction in which the head of the first fastening bolt is seated, to prevent the problem of weakening the rigidity to one side in the tool holder.

[0025] Furthermore, the tool holder includes a groove portion for inserting the reinforcement portion of the cutting insert, and the groove portion includes contact surfaces that contact two sides of the reinforcement portion facing each other.

[0026] Furthermore, while cutting oil supplied from a cutting oil supply unit (not shown) passes through the cutting oil supply pipe and is discharged through the cutting oil supply hole of the tool holder, high-pressure cutting oil is also supplied to the tip of the cutting blade via the branch pipe of the tool holder and the cutting oil supply groove of the cutting blade. This improves cutting performance, enhances the wear resistance of the cutting blade, and reduces the frequency of cutting blade replacement, significantly improving economic efficiency.

[0027] On the other hand, although not explicitly described, the present invention also includes other effects that can be expected from the above configuration. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a perspective view of an indexable drill according to an embodiment of the present invention.

[0029] Figure 2 Show Figure 1 Exploded view of the cutting blade, tool holder, first fastening bolt, and second fastening bolt in the drill bit.

[0030] Figure 3 (a) is Figure 1 A three-dimensional view of the cutting blade of a drill bit, Figure 3 (b) is a stereoscopic image viewed from another direction.

[0031] Figure 4 Observed from another direction Figure 1 A three-dimensional view of the cutting blade of a drill bit.

[0032] Figure 5 yes Figure 1 Cross-sectional view in the AA direction.

[0033] Figure 6 yes Figure 1 A perspective view of a tool holder for drill bits.

[0034] Figure 7 (a) is viewed in the direction of the reinforcement Figure 1 Figure of the cutting blade, Figure 7 (b) is viewed from above Figure 1 Figure of a tool rack.

[0035] Figure 8 It shows Figure 1 Schematic diagram of the cutting oil supply pipe for the drill bit.

[0036] Figure 9 Show Figure 1 Front view of the cutting insert.

[0037] Figure 10 Shown relative to Figure 1 The tightening direction of the first and second tightening bolts of the cutting blade.

[0038] Figures 11 to 13 A conventional drill bit is shown. DETAILED DESCRIPTION

[0039] The embodiments of the present invention are described in detail below with reference to the accompanying drawings so that those skilled in the art can implement them. However, the present invention can be embodied in many different ways and is not limited to the embodiments described here.

[0040] like Figure 1 and Figure 2 As shown, the indexable drill bit according to the embodiment of the present invention includes a replaceable cutting insert 1 , a tool holder 2 for mounting the cutting insert 1 , and a first fastening bolt 3 for fastening the cutting insert 1 to the tool holder 2 .

[0041] like Figures 3 to 5As shown, the cutting insert 1 includes: a cutting insert fastening surface 11, which contacts and is fastened to the tool holder 2; a cutting insert placement surface 14, which contacts and is placed on the tool holder 2; a cutting insert through hole 12, which is formed on the cutting insert fastening surface 11 and is provided for the first fastening bolt 3 to be inserted in the horizontal direction W (refer to FIG. Figure 5 and a reinforcing portion 13, comprising a plane (first plane 134) having a predetermined angle β ° formed with respect to the central axial direction of the tool holder 2 C1 reinforcing portion groove 135, and protruding downward from the lower end portion of the cutting insert 1.

[0042] Specifically, if Figure 4 and Figure 5 As shown, the reinforcement portion 13 of the cutting insert 1 includes a reinforcement groove 135 into which the tip of the second fastening bolt 4, described later, is inserted. The reinforcement groove 135 is formed so that two intersecting planes 133 and 134 are connected at an angle. Here, the tip of the second fastening bolt 4 contacts only the lower plane (first plane 134) and does not contact the upper plane 133 (second plane).

[0043] like Figures 5 to 7 As shown, the tool rack 2 includes: a first tool rack through hole 21 for fastening the first fastening bolt 3, and extending from one side of the tool rack 2 (the first main body 27) to the other side (the second main body The tool holder 2 has a first through-hole 21 extending horizontally therethrough, and a second fastening bolt through-hole 22 located below the first tool holder through-hole 21. The second through-hole 22 extends only from one side of the tool holder 2 (the second main body 28) and has internal threads formed on its inner wall. Furthermore, the tool holder 2 includes a tool holder mounting surface 29 that contacts the cutting insert mounting surface 14 of the cutting insert 1 to support the cutting insert 1.

[0044] The first fastening bolt 3 may have an external thread formed at a distal end thereof, and the external thread may be threadably coupled to an internal thread formed on the second body portion 28 .

[0045] The second fastening bolt 4 is inserted into the second fastening bolt through hole 22 and contacts the first flat surface 134 of the reinforcing portion 13 of the cutting insert 1 so as to be tightened downwardly (at the bottom of the center axis C1 of the tool holder 2). Figure 5 In the H direction, the tightening force is applied downwards. Figure 5As shown, the tip 42 of the second fastening bolt 4 is preferably tapered to achieve line contact with the first flat surface 134 of the reinforcement portion 13. This is because incomplete surface contact can cause machining vibration. This, compared to conventional drills, prevents the cutting insert from vibrating in the vertical direction (H direction) relative to the tool holder during machining by increasing the tightening force of the cutting insert against the tool holder in a direction below the tool holder's central axis C1.

[0046] On the other hand, Figure 5 As shown, the head 31 of the first fastening bolt 3 and the head 41 of the second fastening bolt 4 are located on opposite sides of the tool holder 2 relative to the central axis C1. The first fastening bolt 3 has a typical bolt shape, with the head 31 having a larger diameter than the body. Therefore, a relatively large groove would be formed in the tool holder 2 to accommodate the head 31 of the first fastening bolt 3, potentially weakening the tool holder's rigidity. In view of this, in this embodiment, the through-hole 22 for the second fastening bolt 4 is formed in the opposite direction to the direction in which the head 31 of the first fastening bolt 3 is seated. This prevents the problem of rigidity being weakened toward one side of the tool holder 2. Furthermore, by shaping the second fastening bolt 4 so that the head 41 and body have the same diameter, the size of the through-hole 22 for the second fastening bolt 4 is minimized.

[0047] In addition, if Figure 7 As shown in (a) of FIG. 1 , the reinforcement portion 13 of the cutting insert 1 has a polygonal shape, and in this embodiment, exemplarily has a substantially octagonal shape.

[0048] Accordingly, if Figure 7 As shown in (b), the tool holder 2 includes a groove 23 into which the reinforcement portion 13 is inserted. The groove 23 includes contact surfaces 231 and 232 that contact the two sides 131 and 132 of the reinforcement portion 13 facing each other. Thus, by suppressing the relative rotation of the cutting blade 1 relative to the tool holder 2, cutting vibration can be reduced. On the other hand, as Figure 10 As shown, the two facing edges 131 , 132 are preferably parallel to the tightening direction of the first tightening bolt 3 and the second tightening bolt 4 .

[0049] On the other hand, Figure 7 (a) and Figure 9 As shown, in the cutting insert 1, two cutting insert mounting surfaces 14 are provided with 180° rotational symmetry with respect to the central axis C2 of the cutting insert 1, and the extension lines of the two cutting insert mounting surfaces 14 can form a substantially V-shaped shape with a predetermined angle γ°. For reference, the reinforcement portion 13 is formed on the inner side of the substantially V-shaped shape formed by these cutting insert mounting surfaces 14 (with Figure 9As a reference, the upper side) makes the manufacturing difficulty lower, so that the reinforcement part 13 can be formed on the cutting insert 1 more economically.

[0050] like Figure 4 and Figure 9 As shown, a cutting oil supply groove 16 is formed on the cutting insert fastening surface 11 toward the tip 15 of the cutting insert 1. In addition, it is preferred that the terminal end 162 of the cutting oil supply groove 16 is located at the boundary between the clearance surface 17 and the thinning surface 18 of the cutting insert (refer to FIG. Figure 3 (a)).

[0051] On the other hand, it is preferred that the cutting oil supply groove 16 is formed so that the width gradually decreases from the starting portion 161 toward the terminal portion 162, so that the cross-sectional area decreases. For example, the extension lines of the two side walls of the cutting oil supply groove 16 may be formed to result in α° (refer to Figure 9 ). Thus, the pressure of the cutting oil applied to the tip portion 15 of the cutting insert 1 is increased, thereby increasing the wear resistance of the cutting insert 1.

[0052] like Figure 8 As shown, a cutting oil supply pipe 26 is provided within the tool holder 2. The cutting oil supply pipe 26 extends to the tool holder clearance surface 24 to form a cutting oil supply hole 25. It also includes a branch pipe 27 that branches out midway and connects to the cutting oil supply groove 16 of the cutting insert 1. This allows cutting oil supplied from a cutting oil supply unit (not shown) to be discharged through the cutting oil supply hole 25 of the tool holder 2 while also being supplied at high pressure to the tip 15 of the cutting insert via the branch pipe 27 of the tool holder 2 and the cutting oil supply groove 16 of the cutting insert 1. This improves cutting performance and enhances the wear resistance of the cutting insert, thereby reducing the frequency of cutting insert replacement and significantly improving economic efficiency.

[0053] Although the preferred embodiments of the present invention are described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concepts of the present invention defined in the following claims also fall within the scope of the present invention.

[0054] Industrial Applicability

[0055] The present invention can be used as a cutting tool for processing a workpiece.

Claims

1. An indexable drill bit comprising a replaceable cutting insert, a tool holder for mounting the cutting insert, and a first fastening bolt for fastening the cutting insert to the tool holder, wherein the indexable drill bit is characterized in that: The cutting blade comprises: a cutting insert fastening surface in contact with and fastened to the tool holder; a cutting blade placement surface, which contacts the tool holder and is placed on the tool holder; a cutting insert through-hole formed in the cutting insert fastening surface and allowing the first fastening bolt to pass through in a lateral direction; and a reinforcement portion having a reinforcement portion groove having a first plane forming a predetermined angle with respect to the axial direction of the tool holder and protruding downward from the lower end portion of the cutting insert, The tool rack comprises: a first tool rack through hole, for fastening the first fastening bolt, and passing through the tool rack in a horizontal direction from one side to the other side; as well as The second fastening bolt through hole is located on the lower side of the tool rack through hole, penetrates only from one side of the tool rack, and is formed with an internal thread. A second fastening bolt is inserted into the second fastening bolt through hole and contacts the first flat surface of the reinforcing portion to apply a fastening force downwardly toward the center axis of the tool holder. The position of the head of the first fastening bolt and the position of the head of the second fastening bolt are located on opposite sides with respect to the central axis of the tool holder. The reinforcement portion has a polygonal shape, The tool holder includes a groove for inserting the reinforcement portion, and the groove includes contact surfaces that contact two sides of the reinforcement portion facing each other to prevent the cutting insert from rotating relative to the tool holder. Two cutting insert placement surfaces are provided 180° rotationally symmetrically with respect to the central axis of the cutting insert, and the extension lines of the cutting insert placement surfaces are V-shaped with a predetermined angle. The first plane is located above the intersection of the extension lines. A cutting oil supply groove is formed on the cutting insert fastening surface toward a tip portion of the cutting insert.

2. The indexable drill bit according to claim 1, characterized in that A tip portion of the second fastening bolt is formed in a tapered shape, and the tip portion is in line contact with the first plane of the reinforcement portion.

3. The indexable drill bit according to claim 1, characterized in that The cutting oil supply groove is formed so that its width gradually decreases from a starting portion toward a terminal portion, so that a cross-sectional area decreases.

4. The indexable drill according to claim 3, characterized in that The tool holder is provided with a cutting oil supply pipe, The cutting oil supply pipe leads to the tool holder clearance surface to form a cutting oil supply hole, and includes a branch pipe that branches in the middle and is connected to the cutting oil supply groove to communicate.

5. The indexable drill bit according to claim 1, characterized in that The terminal end of the cutting oil supply groove is located at a boundary between the clearance surface and the thinning surface of the cutting insert.

6. The indexable drill bit according to claim 1, characterized in that The diameter of the head of the first fastening bolt is larger than the diameter of the body, and the diameter of the head of the second fastening bolt is the same as the diameter of the body.

7. The indexable drill according to claim 2, characterized in that The reinforcement groove includes the first planes intersecting each other at an angle, and the second planes located above the first planes and connected to each other. The tip of the second fastening bolt contacts only the first plane and does not contact the second plane.

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