WO2013105770A1

WO2013105770A1 - Cutting insert, tool body and cutting tool assembly comprising the sames

Info

Publication number: WO2013105770A1
Application number: PCT/KR2013/000129
Authority: WO
Inventors: Byung Gyun Bae
Original assignee: Taegutec Ltd.
Priority date: 2012-01-10
Filing date: 2013-01-08
Publication date: 2013-07-18
Also published as: KR20130081912A

Abstract

Embodiments of a cutting tool assembly having a cutting insert and a tool body are provided. The cutting insert has an upper surface, a lower surface, flank surfaces and a protrusion. The lower surface is parallel to the upper surface. The flank surfaces are inclined with respect to the upper surface and the lower surface between the upper surface and the lower surface. The protrusion protrudes from the lower surface and has a truncated hemispherical shape. The tool body has a pocket, a recess and an engagement portion. The pocket has a bottom surface and side wall. The recess is concave from the bottom surface of the pocket and engages the protrusion. The engagement portion is provided in the side wall and engages the flank surface of the cutting insert in a dovetail engagement.

Description

CUTTING INSERT, TOOL BODY AND CUTTING TOOL ASSEMBLY COMPRISING THE SAMES

The present invention relates to a cutting insert, a tool body and a cutting tool assembly comprising the cutting insert and the tool body.

A cutting tool assembly for turning includes a cutting insert and a tool body. The cutting insert has a cutting portion for cutting a workpiece and is replaceably mounted to a leading edge of the tool body. When the cutting tool assembly cuts a workpiece, the cutting insert may move or rotate relative to the tool body due to a cutting resistance from the workpiece. This may deteriorate cutting precision. Particularly, when the cutting insert is elongated in a length direction of the tool body, the cutting insert may move or rotate relative to the tool body due to the rotary moment acting on the cutting portion of the cutting insert.

The present invention is directed to solving the aforementioned problems of the prior art. The present invention provides a cutting insert, a tool body and a cutting tool assembly including the cutting insert and the tool body, which can prevent the cutting insert from moving or rotating relative to the tool body.

In an exemplary embodiment according to one aspect of the present invention, a cutting tool assembly includes a cutting insert having a cutting portion and a tool body separably coupled to the cutting insert. The cutting insert includes: an upper surface, a lower surface parallel to the upper surface; flank surfaces between the upper surface and the lower surface; and a protrusion. The flank surfaces are inclined with respect to the upper surface and the lower surface. The protrusion protrudes from the lower surface and has a truncated hemispherical shape. The tool body includes: a pocket having a bottom surface and a side wall; a recess concave from the bottom surface; and an engagement portion provided in the side wall. The recess engages the protrusion of the cutting insert. The engagement portion engages the flank surface of the cutting insert in a dovetail engagement.

In an embodiment of the present invention, the protrusion has a guide surface that is formed on a peripheral surface thereof. The guide surface is flat in a circumferential direction parallel to the lower surface and is curved in a circumferential direction perpendicular to the lower surface.

In an embodiment of the present invention, a section shape surrounded by the upper surface, the flank surfaces and the lower surface includes a trapezoid.

In an embodiment of the present invention, the lower surface is rotational symmetrical by 180 degrees with respect to the upper surface.

In an embodiment of the present invention, the recess is conical. The recess has opposing flat guide surfaces.

In an embodiment of the present invention, the engagement portion includes first and second engagement portions contacting the flank surface. The first and second engagement portions are positioned symmetrically to each other. A sectional shape of the first and second engagement portions, which is taken parallel to the bottom surface of the pocket, is curved. Further, a sectional shape of the first and second engagement portions, which is taken perpendicularly to the bottom surface of the pocket, includes trapezoid.

In an exemplary embodiment according to a further aspect of the present invention, a cutting insert incudes: an upper surface; a lower surface parallel to the upper surface; flank surfaces between the upper surface and the lower surface; and a protrusion. The lower surface is rotational symmetrical with respect to the upper surface. The flank surfaces are inclined with respect to the upper surface and the lower surface. The protrusion protrudes from the lower surface and has a truncated hemispherical shape.

In an exemplary embodiment according to a still further aspect of the present invention, a tool body includes a pocket that has a bottom surface and a side wall for receiving a cutting insert. The pocket includes a recess and an engagement portion. The recess is concave from the bottom surface. The engagement portion is provided in the side wall and has first and second engagement portions that are positioned symmetrically to each other.

According to the cutting tool assembly of the present invention, the cutting insert includes a protrusion having a truncated hemispherical shape. Further, the tool body includes a conical recess engaging the protrusion and an engagement portion engaging the flank surface of the cutting insert in a dovetail engagement. Thus, it is possible to prevent the cutting insert from moving or rotating relative to the tool body.

FIG. 1 is a perspective view of a cutting tool assembly according to one embodiment.

FIG. 2 is a perspective view of a cutting insert shown in FIG. 1.

FIG. 3 is a top view of the cutting insert shown in FIG. 2.

FIG. 4 is a side view of the cutting insert shown in FIG. 2.

FIG. 5 is a schematic sectional view taken along the line 5-5 of FIG. 2.

FIG. 6 is a schematic sectional view taken along the line 6-6 of FIG. 2.

FIG. 7 is a schematic sectional view taken along the line 7-7 of FIG. 2.

FIG. 8 is a perspective view of a tool body shown in FIG. 1.

FIG. 9 is a top view of the tool body shown in FIG. 8.

FIG. 10 is a front view of the tool body shown in FIG. 8.

FIG. 11 is a schematic sectional view taken along the line 11-11 of FIG. 9.

FIG. 12 is a sectional view showing an exemplary assembly of the cutting insert and the tool body.

FIG. 13 is a top view showing “A” portion of FIG. 1.

Embodiments of a cutting insert, a tool body and a cutting tool assembly will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, a cutting tool assembly 100 according to one embodiment of the present invention comprises a cutting insert 200, a tool body 300 and a screw 400. As shown in FIG. 1, the cutting tool assembly 100 has an X-axis and a Y-axis, which pass through the opposing two vertices of the cutting insert 200, respectively. The X-axis extends in a length direction of the cutting insert 200 and the tool body 300, while the Y-axis is perpendicular to the X-axis. The cutting insert 200 is separably coupled to the tool body 300. The cutting insert 200 is secured to the tool body 300 by means of the screw 400.

Referring to FIGS. 2 to 4, the cutting insert 200 includes an upper surface 201, a lower surface 202 and a flank surface 203 extending from the upper surface 201 to the lower surface 202 in a thickness direction of the cutting insert 200. The upper surface 201 and the lower surface 202 may have one of a trapezoid shape, a parallelogram shape and a lozenge shape. In this embodiment, the upper surface 201 and the lower surface 202 have a lozenge shape.

The upper surface 201 and the lower surface 202 are symmetrical about the X-axis, but asymmetrical about the Y-axis. The upper surface 201 comprises a first upper surface 201a and a second upper surface 202b that are divided relative to the Y-axis. The lower surface 202 comprises a first lower surface 202a and a second lower surface 202b that are divided relative to the Y-axis. The lower surface 202 is rotational symmetrical by 180 degrees with respect to the upper surface 201. That is, the first upper surface 201a corresponds to the first lower surface 202a, while the second upper surface 201b corresponds to the second lower surface 202b.

The flank surface 203 comprises a first flank surface 203a, which is located between the first upper surface 201a and the second lower surface 202b, and a second flank surface 203b, which is located between the second upper surface 201b and the first lower surface 202a. The first and

second flank surfaces

203a, 203b comprise a flat surface. The first flank surface 203a is inclined with respect to the first upper surface 201a and the second lower surface 201b. Specifically, the first flank surface 203a is inclined at an acute angle with respect to the first upper surface 201a and at an obtuse angle with respect to the second lower surface 202b. That is, as shown in FIG. 5, a sectional shape which is surrounded by the first upper surface 201a, the second lower surface 202b and the first flank surface 203a may have an inverted trapezoid shape. Thus, the first upper surface 201a is broader than the second lower surface 202b. The second flank surface 203b is inclined with respect to the second upper surface 201b and the first lower surface 202a. Specifically, the second flank surface 203b is inclined at an obtuse angle with respect to the second upper surface 201b and at an acute angle with respect to the first lower surface 202a. That is, as shown in FIG. 6, a sectional shape, which is surrounded by the second upper surface 201b, the first lower surface 202a and the second flank surface 203b, may have a trapezoid shape. Thus, the first lower surface 202a is broader than the second upper surface 201b. The cutting insert 200 and the tool body 300 engage each other in a dovetail engagement and the first flank surface 203a or the second flank surface 203b of the cutting insert 200 contacts the engagement portion 330 of the tool body 300 through such engagement.

The cutting insert 200 includes a protrusion, a cutting portion and a mounting bore. Said protrusion comprises a first protrusion 211, which protrudes upwardly from the second upper surface 201b, and a second protrusion 213, which protrudes downwardly from the second lower surface 202b. The first and

second protrusions

211, 213 may have a hemispherical shape or a truncated hemispherical shape. In this embodiment, as shown in FIG. 4, the first and

second protrusions

211, 213 have a truncated hemispherical shape. The term truncated hemispherical shape as used herein refers to a shape wherein a portion of a hemisphere adjacent to its apex is removed or cut parallel to a base side of such a hemisphere. As shown in FIG. 4, an apex portion of the first protrusion 211 is removed and an upper end portion of the first protrusion 211 is parallel to the second upper surface 201b, while an apex portion of the second protrusion 213 is removed and a lower end portion of the second protrusion 213 is parallel to the second lower surface 202b.

The first protrusion 211 includes a first guide surface 212 that is formed along a peripheral surface thereof. The first guide surface 212 has a band shape having a predetermined width. The first guide surface 212 may be formed by cutting the peripheral surface of the first protrusion 211 having a truncated hemispherical shape. In the top view shown in FIG. 3, the first guide surface 212 is perpendicular to the X-axis and parallel to the Y-axis. The first guide surface 212 is flat in a circumferential direction parallel to the second upper surface 201b (i.e., a longitudinal direction of the first protrusion 211). The second guide surface 212 is curved in a circumferential direction perpendicular to the second upper surface 201b (i.e., a latitudinal direction of the first protrusion 211). Since the first guide surface 212 is formed by cutting the peripheral surface of the first protrusion 211, the first guide surface 212 may have a radius of curvature smaller than that of the first protrusion 211. A second guide surface 214 of the second protrusion 213 has the same shape as the first guide surface 211.

Said cutting portion comprises a first cutting portion 221, which is formed at an edge between the first upper surface 201a and the first flank surface 203a, and a second cutting portion 222, which is formed at an edge between the first lower surface 202a and the second flank surface 203b. For example, when the cutting insert 200 is mounted to the tool body 300 as shown in FIG. 1, the first cutting portion 221 cuts the workpiece. On the contrary thereto, when the cutting insert 200 is mounted to the tool body 300 with the lower surface 202 facing upward, the second cutting portion 222 cuts the workpiece.

The mounting bore 230 penetrates through the upper surface 201 and the lower surface 202 and is inclined with respect to the upper surface 201 and the lower surface 202. As shown in FIG. 7, a central axis C1 of the mounting bore 230 makes a predetermined angle with respect to the upper surface 201 and the lower surface 202.

Referring to FIGS. 8 to 11, the tool body 300 includes a pocket 310, a recess 321, an engagement portion 330 and a screw hole 340. In another embodiment, the pocket 310 may include the recess 321 and the engagement portion 330.

The pocket 310 is formed in a front edge of the tool body 300 and receives the cutting insert 200. The pocket 310 has a bottom surface 311 and side walls 312. The bottom surface 311 contacts at least a portion of the first upper surface 201a or the first lower surface 202a. The side walls 312 are perpendicular to the bottom surface 311.

The recess 321 is concave from the bottom surface 311 of the pocket 310 and engages the first protrusion 211 or the second protrusion 213. As shown in FIGS. 8 and 11, the recess 321 has an inverted conical shape. Opposing third guide surfaces 322 are formed on the recess 321. The third guide surface 322 is flat and has a band shape having a predetermined width. As shown in FIG. 9, the third guide surface 322 is perpendicular to the X-axis and parallel to the Y-axis. The third guide surface 322 may have the same width as the width of the first guide surface 212 of the first protrusion 211 or the width of the second guide surface 214 of the second protrusion 213.

The engagement portion 330 is provided in the side walls 312 of the pocket 310. The engagement portion 330 contacts the first flank surface 203a or the second flank surface 203b. The engagement portion 330 comprises a first engagement portion 331 and a second engagement portion 332 that are symmetrical about the X-axis. As shown in FIG. 9, a planar shape of the first and second engagement portions 331, 332 (or a sectional shape of the first and

second engagement portions

331, 332 taken in a plane parallel to the bottom surface 311) is convex toward the X-axis. Further, the first and

second engagement portions

331, 332 are inclined with respect to the bottom surface 311 of the pocket 310. That is, as shown in FIG. 10, a Y-axis directional distance d between the first engagement portion 331 and the second engagement portion 332 becomes greater from top to bottom. A sectional shape of the first and

second engagement portions

331, 332, which is taken in a plane perpendicular to the bottom surface 311, or a front shape of the first and

second engagement portions

331, 332 shown in FIG. 10 corresponds to the cross-sectional shape which is surrounded by the second upper surface 201b, the first lower surface 202a and the second flank surface 203b of the cutting insert 200 (e.g., a trapezoid shape shown in FIG. 6).

The screw hole 340 is a bore that penetrates through the tool body 500 or a hole that is perforated in the tool body at a predetermined depth. The screw hole 340 has a thread for thread-engagement with the screw 400. The screw 400 penetrates through the mounting bore 230 of the cutting insert 200 and thread-engages the screw hole 340 of the tool body 300. As shown in FIG. 11, a central axis C2 of the screw hole 340 is inclined with respect to the bottom surface 311 of the pocket 310. When the cutting insert 200 is completely mounted to the tool body 300, the central axis C2 of the screw hole 340 may be coaxial with the central axis C1 of the mounting bore 230.

Descriptions are made as to an exemplary assembly of the cutting insert and the tool body with reference to FIGS. 12 and 13.

When the cutting insert 200 and the tool body 300 are assembled together, the second flank surfaces 203b of the cutting insert 200 engage the first and

second engagement portions

331, 332 in a dovetail engagement and the second protrusion 213 engages the recess 321 as partially inserted to the recess 321. Further, the first lower surface 202a of the cutting insert 200 is in contact with the bottom surface 311 of the pocket 310 and the second lower surface 202b is spaced from the bottom surface 311 of the pocket 310. When the cutting insert 200 is mounted to the tool body 300, the cutting insert 200 is placed on the pocket 310 with the second protrusion 213 facing downward. The cutting insert 200 is placed on the bottom surface 311 at an angle due to the second protrusion 213 protruding downwardly. Since the second protrusion 213 has a truncated hemispherical shape, the inclination of the cutting insert 200, which is placed on the bottom surface 311, is decreased. Thus, the cutting insert 200 can be easily mounted to the pocket 310 of the tool body 300.

The screw 400 penetrates through the mounting bore 230 of the cutting insert 200 and then thread-engages the screw hole 340 of the tool body 300. As the screw 400 thread-engages the screw hole 340, the second protrusion 213 slips downwardly along an inclined surface of the recess 321. At this time, the second guide surface 214 and the third guide surface 322 help the slip of the second protrusion 213 since they has the flat surfaces along the X-axis direction. Thus, the cutting insert 200 moves in the X-axis direction relative to the tool body 300 as indicated by arrows in FIG. 12. As a result, as shown in FIG. 13, the second flank surfaces 203b are brought into point contact or surface contact with the first and

second engagement portions

331, 332. Further, the second guide surface 214 of the second protrusion 213 is in point contact or surface contact with the third guide surface 322 of the recess 321. When a cutting resistance increases during the cutting operation of the cutting tool assembly 100 for a workpiece, the second flank surface 203b may come into surface contact with the first and

second engagement portions

331, 332. When the cutting insert 200 is completely mounted to the tool body 300, the contact between the cutting insert 200 and the tool body 300 makes a triangle through the second protrusion 213, the first engagement portion 331 and the second engagement portion 332. This prevents the cutting insert 200 from rotating or moving relative to the tool body 300 in any direction.

While the present invention has been described herein with reference to the foregoing embodiments depicted in the accompanying drawings, the present invention should not be limited thereto. It will be apparent to those of ordinary skill in the art that various substitutions, alternations or modifications may be made without departing from the scope of the present invention.

Claims

A cutting tool assembly, comprising:

a cutting insert having a cutting portion; and

a tool body separably coupled to the cutting insert,

wherein the cutting insert includes:

an upper surface;

a lower surface parallel to the upper surface;

flank surfaces inclined with respect to the upper surface and the lower surface between the upper surface and the lower surface; and

a protrusion protruding from the lower surface and having a truncated hemispherical shape; and

wherein the tool body includes:

a pocket having a bottom surface and a side wall;

a recess concave from the bottom surface and engaging the protrusion; and

an engagement portion provided in the side wall and engaging the flank surface of the cutting insert in a dovetail engagement.
The cutting tool assembly of Claim 1, wherein the protrusion has a guide surface formed on a peripheral surface thereof.
The cutting tool assembly of Claim 2, wherein the guide surface is flat in a circumferential direction parallel to the lower surface and is curved in a circumferential direction perpendicular to the lower surface.
The cutting tool assembly of Claim 1, wherein a sectional shape surrounded by the upper surface, the flank surfaces and the lower surface includes a trapezoid shape.
The cutting tool assembly of Claim 1, wherein the lower surface is rotational symmetrical by 180 degrees with respect to the upper surface.
The cutting tool assembly of Claim 1, wherein the recess is conical.
The cutting tool assembly of Claim 6, wherein the recess has opposing guide surfaces.
The cutting tool assembly of Claim 7, wherein the guide surfaces are flat.
The cutting tool assembly of Claim 1, wherein the engagement portion comprises first and second engagement portions contacting the flank surface, the first and second engagement portions being positioned symmetrically to each other.
The cutting tool assembly of Claim 9, wherein a sectional shape of the first and second engagement portions, which is taken parallel to the bottom surface of the pocket, is curved.
The cutting tool assembly of Claim 9, wherein a sectional shape of the first and second engagement portions, which is taken perpendicularly to the bottom surface of the pocket, is trapezoid.
A cutting insert, comprising:

an upper surface;

a lower surface parallel to the upper surface and rotational symmetrical with respect to the upper surface;

flank surfaces inclined with respect to the upper surface and the lower surface between the upper surface and the lower surface; and

a protrusion protruding from the lower surface and having a truncated hemispherical shape.
A tool body comprising a pocket having a bottom surface and a side wall for receiving a cutting insert,

wherein the pocket comprises:

a recess concave from the bottom surface; and

an engagement portion provided in the side wall and having first and second engagement portions positioned symmetrically to each other.
The tool body of Claim 13, wherein the recess is conical.