WO2009157603A1

WO2009157603A1 - Cutting insert and method of manufacturing the same

Info

Publication number: WO2009157603A1
Application number: PCT/KR2008/003738
Authority: WO
Inventors: Chang Hee Choi; Chang Gyu Park
Original assignee: Taegutec Ltd.
Priority date: 2008-06-26
Filing date: 2008-06-27
Publication date: 2009-12-30
Also published as: KR100978424B1; KR20100001061A; CN102076450A

Abstract

The cutting insert comprises a top surface, a bottom surface, major side surfaces connecting the top and bottom surfaces, and minor side surfaces connecting the adjacent major side surfaces. The top surface comprises major top surfaces adjacent to the major side surfaces, minor top surfaces adjacent to the minor side surfaces, connecting the adjacent major top surfaces, and formed to be higher than the major top surfaces, and a central surface surrounded by the major top surfaces and the minor top surfaces. The major top surfaces and the major side surfaces are unground surfaces, while the minor top surfaces and the minor side surfaces are ground surfaces. A major cutting edge is formed between the major top surface and the major side surface, which are unground surfaces. A minor cutting edge is formed between the minor top surface and the minor side surface, which are ground surfaces.

Description

CUTTING INSERT AND METHOD OF MANUFACTURING THE

SAME

Technical Field

[1] The present invention relates to a cutting insert and a method of manufacturing the same. In particular, the present invention relates to a cutting insert, which minimizes grinding processes conducted on a surface of the cutting insert and maintains a surface roughness of a surface of a workpiece. Background Art

[2] Generally, a cutting insert mounted on a milling cutter is manufactured by compressing powder (e.g., tungsten carbide) to be in a predetermined shape of the cutting insert. It is then sintered at a temperature between about 1300 and 1400 Celsius degrees. The cutting insert manufactured by the above process has great manufacturing tolerances. As such, the surface of the cutting insert is ground after the compressing and sintering steps, thereby reducing a position difference of each cutting edge. Such a cutting insert is disclosed in U.S. Patent Application Publication No. 2007/183858. In such a cutting insert, all the surfaces of the cutting insert are ground, except for a top surface adjacent to a major cutting edge.

[3] However, since the grinding step typically takes a very long time, it is necessary to minimize the timing of such a step as much as possible.

[4] Fig. 1 shows a conventional milling cutter and Fig. 2 shows a conventional cutting insert (10) mounted on the milling cutter. The cutting insert (10) comprises: a top surface (12); a bottom surface (14); major side surfaces (16) connecting the top surface (12) and the bottom surface (14); minor side surfaces (18) connecting the adjacent major side surfaces (16); major cutting edges (20) formed between the top surface (12) and the major side surfaces (16); and minor cutting edges (22) formed between the top surface (12) and the minor side surfaces (18).

[5] Fig. 3 shows the process of cutting a workpiece with the conventional cutting insert

(10) mounted on the milling cutter. Fig. 4 illustrates an enlarged view of the cutting insert (10) shown in Fig. 3. As shown in Figs. 3 and 4, the major cutting edge (20) of the cutting insert (10) initially cuts the workpiece along a feeding direction of the milling cutter. Subsequently, the minor cutting edge (22) smoothens the workpiece, which has been cut by the major cutting edge (20). Thus, although there is to some extent a position difference among the major cutting edges (20) on the milling cutter, the surface roughness of the surface of the workpiece may be maintained so long as positions of the minor cutting edges (22) are even with respect to each other. [6] Given that the surface roughness of the surface of the workpiece is controlled by the position difference among the minor cutting edges (22), it may be considered to grind only the bottom surface (14), which contacts with a seating surface of the milling cutter and the minor side surface (18) adjacent to the minor cutting edge (22).

[7] However, in such a case, since the top surface (12) of the cutting insert (10) is not grinded as shown in Fig. 5, there may be an error (M) in the position of the minor cutting edge (22) on the milling cutter, which is caused by the manufacturing tolerance in a thickness direction from the top surface (12) to the bottom surface (14). Thus, in case the surface of the workpiece is cut by the milling cutter on which a plurality of such cutting inserts (10) are seated, the surface roughness of the surface of the workpiece may deteriorate compared to when grinding all the surfaces of the cutting insert.

Disclosure of Invention Technical Problem

[8] The present invention seeks to provide a solution to the aforementioned drawback of the conventional cutting insert. Specifically, the present invention provides a cutting insert that can make the surface roughness of the workpiece as if the workpiece is cut by the cutting insert, the surfaces of which are all ground, while minimizing the grinding process on the surface of the cutting insert. Technical Solution

[9] The cutting insert of the present invention comprises a top surface, a bottom surface, major side surfaces connecting the top and bottom surfaces, and minor side surfaces connecting the adjacent major side surfaces. The top surface comprises major top surfaces adjacent to the major side surfaces, minor top surfaces adjacent to the minor side surfaces, connecting the adjacent major top surfaces and formed to be higher than the major top surfaces, and a central surface surrounded by the major top surfaces and the minor top surfaces. The major top surfaces and the major side surfaces are unground surfaces, while the minor top surfaces and the minor side surfaces are ground surfaces. A major cutting edge is formed between the major top surface and the major side surface, which are unground surfaces. A minor cutting edge is formed between the minor top surface and the minor side surface, which are ground surfaces.

Advantageous Effects

[10] According to the present invention, since the minor top surface and the minor side surface forming the minor cutting edge are ground, the manufacturing tolerance in a thickness direction from the minor top surface to the bottom surface is reduced. Further, the position of the minor cutting edge on the milling cutter is made to be uniform. Also, since the major top surface and the major side surface are not ground, which form the main cutting edge that does not have an effect on the surface roughness of the surface of the workpiece, the time and cost spent in the grinding step can be reduced. Thus, according to the present invention, while minimizing grinding processes on the surfaces of the cutting insert, the surface roughness of the workpiece can be made as if the workpiece is cut by the cutting insert, the surfaces of which are all ground. Brief Description of the Drawings

[11] Fig. 1 shows a milling cutter on which a plurality of cutting inserts are seated.

[12] Fig. 2 is a perspective view of a conventional cutting insert.

[13] Fig. 3 shows cutting a surface of the workpiece with the milling cutter on which a plurality of cutting inserts are seated.

[14] Fig. 4 is an enlarged view of the cutting insert of Fig. 3.

[15] Fig. 5 is a sectional view of the minor cutting edge of the cutting insert shown in Fig.

2.

[16] Fig. 6 illustrates a perspective view of the cutting insert according to an embodiment of the present invention.

[17] Fig. 7 illustrates a perspective view of the cutting insert according to another embodiment of the present invention.

[18] Fig. 8 illustrates a perspective view of the cutting insert according to another embodiment of the present invention.

[19] Fig. 9 illustrates a perspective view of the cutting insert according to yet another embodiment of the present invention with the top surface oriented upward.

[20] Fig. 10 illustrates a perspective view of the cutting insert according to yet another embodiment of the present invention with the bottom surface oriented upward. Mode for the Invention

[21] The present invention will now be described in detail with reference to the embodiments of the present invention.

[22] Fig. 6 illustrates a perspective view of the cutting insert (100) according to the present invention. The cutting insert (100) comprises a top surface (120) and a bottom surface (140). The top surface (120) and the bottom surface (140) are connected by major side surfaces (161). The adjacent major side surfaces (161) are connected by minor side surfaces (162). The top surface (120) includes a major top surface (121) adjacent to the major side surfaces (161), minor top surfaces (122) connecting the adjacent major top surfaces (121), adjacent to the minor side surfaces (162), and formed to be higher than the major top surfaces (121), and a central surface (123) surrounded by the major top surfaces (121) and the minor top surfaces (122). The major top surfaces (121) and the major side surfaces (161) are unground surfaces, while the minor top surfaces (122) and minor side surfaces (162) are ground surfaces. A major cutting edge (181) is formed between the major top surfaces (121) and the major side surfaces (161), which are unground surfaces. A minor cutting edge (182) is formed between the minor top surfaces (122) and the minor side surfaces (162), which are ground surfaces.

[23] Since the minor top surface (122) and the minor side surface (162) forming the minor cutting edge (182) are ground to ensure position precision and reduce position tolerance, the manufacturing tolerance in a thickness direction from the minor top surface (122) to the bottom surface (140) is reduced and the position of the minor cutting edge (182) on the milling cutter is made to be uniform. Also, since the major top surface (121) and the major side surface (161) are not ground, which form the main cutting edge (181) that does not have an effect on the surface roughness of the surface of the workpiece, the time and cost spent in the grinding process can be reduced. Thus, according to the present invention, while minimizing grinding processes on the surfaces of the cutting insert, the surface roughness of the workpiece can be made as if the workpiece is cut by the cutting insert, the surfaces of which are all ground.

[24] In order to make the position of the minor cutting edge (182) on the milling cutter more uniform, the bottom surface (140), which is brought in contact with a seating surface of the milling cutter, is preferably ground. Further, the central surface (123) is preferably ground and formed to be coplanar with the minor top surfaces (122). This is because when the cutting insert (100) is seated onto the milling cutter, the central surface (123) is brought in contact with a wedge.

[25] A method of manufacturing the cutting insert according to the present invention will be explained below.

[26] Initially, a dried raw powder is compressed to form a green body having the aforementioned shape of the cutting insert. The green body is sintered to form a sintered body. The sintered body is then grinded. When the sintered body is ground, only the minor top surfaces (122) and the minor side surfaces (162) are ground without the major top surfaces (121) and the major side surfaces (161) of the sintered body being ground.

[27] In the grinding step of the sintered body, the bottom surface (140) is also preferably ground. Further, in the grinding step, the minor top surfaces (122) are preferably ground together with the central surface (123).

[28] Further, the major top surface (121) of the green body formed by compressing the raw powder is preferably formed to be at least 0.1 mm lower than the minor top surface (122). Otherwise, after sintering the green body, the height of the minor top surface (122) becomes the same as or lower than that of the major top surface (121). Thus, the major top surface (12) of the sintered body may be also undesirably ground during grinding the minor top surface (121) of the sintered body.

[29] Although the present invention will now be described with reference to its embodiments, such embodiments of the present invention are only exemplary. A person skilled in the art should understand that various modifications to the embodiments may be also applied without departing from the scope of the present invention.

[30] For example, Fig. 6 illustrates a cutting insert seated onto the milling cutter in a wedge type. However, as shown in Figs. 7 and 8, a person skilled in the art may consider a cutting insert seated onto the milling cutter in a screw type. In such a case, as shown in Fig. 7, the central surface (223) may be configured to be an unground surface in the same manner as the major top surface (221) in order to further reduce any material loss due to the grinding process. Also, as shown in Fig. 8, the central surface (323) may be coplanar with the minor top surfaces (322). Further, when manufacturing the cutting insert shown in Fig. 7, the minor top surfaces (222) of the green body is preferably formed to be at least 0.1 mm higher than any of the major top surface (221) and the central surfaces (223). When manufacturing the cutting insert as shown in Fig. 8, any of the minor top surfaces (322) and the central surface (323) of the green body is preferably formed to be at least 0.1 mm higher than the major top surface (321).

[31] Figs. 6 to 8 illustrate a cutting insert using only a top surface during cutting.

However, as shown in Figs. 9 and 10, a person skilled in the art may consider a cutting insert using top and bottom surfaces during cutting. In such a case, a bottom surface (440) comprises major bottom surfaces (441), minor bottom surfaces (442), and a central bottom surface (443), in the similar manner as a top surface (420). Each side surface comprises first minor side surfaces (462) adjacent to the minor bottom surfaces (442) and forming minor bottom cutting edges (484) together with the minor bottom surfaces (442), and second minor side surfaces (463) adjacent to the minor top surfaces (422) and forming minor top cutting edges (482) together with the minor top surfaces (422). The minor top surfaces (422), the minor bottom surfaces (442), and the first and second minor side surfaces (462, 463) are ground.

[32]

Claims

[1] A cutting insert comprising: a top surface; a bottom surface; major side surfaces connecting the top and bottom surfaces; and minor side surfaces connecting the adjacent major side surfaces; wherein the top surface comprises major top surfaces adjacent to the major side surfaces, minor top surfaces adjacent to the minor side surfaces, connecting the adjacent major top surfaces, and formed to be higher than the major top surfaces, and a central surface surrounded by the major top surfaces and the minor top surfaces; wherein the major top surfaces and the major side surfaces are unground surfaces, and the minor top surfaces and the minor side surfaces are ground surfaces; and wherein a major cutting edge is formed between the major top surface and the major side surface, which are unground surfaces, and a minor cutting edge is formed between the minor top surface and the minor side surface, which are ground surfaces.

[2] The cutting insert according to Claim 1, wherein the bottom surface is a ground surface.

[3] The cutting insert according to Claim 1, wherein the central surface is a ground surface formed to be coplanar with the minor top surfaces.

[4] The cutting insert according to Claim 1, wherein the central surface is an unground surface.

[5] A cutting insert comprising: a top surface; a bottom surface; major side surfaces connecting the top and bottom surfaces; and minor side surfaces connecting the adjacent major side surfaces, each having a first minor side surface and a second minor side surface; wherein the top surface comprises major top surfaces adjacent to the major side surfaces and the first minor side surfaces, minor top surfaces adjacent to the second minor side surfaces, connecting the adjacent major top surfaces, and formed to be higher than the major top surfaces; wherein the bottom surface comprises major bottom surfaces adjacent to the major side surfaces and the second minor side surfaces, minor bottom surfaces adjacent to the first minor side surfaces, connecting the adjacent major bottom surfaces, and formed to be higher than the major bottom surfaces; wherein the major top surfaces, the major bottom surfaces, and the major side surfaces are unground surfaces, and the minor top surfaces, the minor bottom surfaces, and the first and second minor side surfaces are ground surfaces; wherein major cutting edges are formed between the major top surface, the major side surface and the first minor side surface, and between the major bottom surface, the major side surface and the second minor side surface, respectively; and wherein minor cutting edges are formed between the minor top surface and the second minor side surface, and between the minor bottom surface and the first minor side surface, respectively. [6] A method of manufacturing the cutting insert of Claim 1, the method comprising: preparing a raw powder; compressing the raw powder to form a green body; sintering the green body to form a sintered body; and grinding minor top surfaces and minor side surfaces of the sintered body. [7] The method according to Claim 6, wherein grinding minor top surfaces and minor side surfaces of the sintered body comprises grinding the bottom surface. [8] The method according to Claim 6, wherein grinding minor top surfaces and minor side surfaces of the sintered body comprises grinding the central surface. [9] The method according to Claim 6, wherein compressing the raw powder to form a green body comprises forming the major top surface to be lower than the minor top surface. [10] The method according to Claim 9, wherein compressing the raw powder to form a green body comprises forming the major top surface to be at least 0.1 mm lower than the minor top surface. [11] A method of manufacturing the cutting insert of Claim 5, the method comprising: preparing a raw powder; compressing the raw powder to form a green body; sintering the green body to form a sintered body; and grinding minor top surfaces, minor bottom surfaces, and first and second minor side surfaces of the sintered body. [12] The method according to Claim 11, wherein compressing the raw powder to form a green body comprises forming the major top surface and the major bottom surface to be lower than the minor top surface and minor bottom surface, respectively. [13] The method according to Claim 12, wherein compressing the raw powder to form a green body comprises forming the major top surface and the major bottom surface to be at least 0.1 mm lower than the minor top surface and minor bottom surface, respectively.