KR20190067989A - Cutting insert having good fastening force - Google Patents

Abstract

The present invention relates to a cutting insert with increased coupling force for processing a difficult to cut material, which has increased the coupling force or thermal conductivity to extend its service life when a ceramic or cubic-boron nitride (cBN) insert is coupled to a holder installed in the main body of a tool. According to the present invention, the cutting insert comprises: upper and lower surfaces; a side surface connecting the upper and lower surfaces; and a cut-in part formed by the upper and side surfaces. A coupling assist layer is inserted or coated formed on the outermost surface of the cutting insert to cover a part or all of the coupling surface coupled to the holder of the main body of the tool. The coupling assist layer comprises a base material forming the cutting insert, or material with at least one characteristic among materials with greater hardness, better softness, and higher conductivity than those of a hard coating film formed on the surface of the base material of the cutting material. When the cutting insert is coupled to the holder, elastic or plastic deformation is generated in the coupling assist layer such that the contact area coupled to the cutting insert and the holder of the main body of the tool is increased, wherein the cutting insert is a ceramic or cBN insert.

Description

[0001] CUTTING INSERT HAVING GOOD FASTENING FORCE [0002]

More particularly, the present invention relates to a cutting insert for machining a hard cutting material, and more particularly, to a cutting insert for machining a hard cutting material, which has improved fastening force and / or thermal conductivity when a ceramic insert or a cBN insert, To an extended cutting insert.

When the cutting insert is fastened to the holder of the tool body, the entire engagement surface of the cutting insert does not contact the holder of the tool body, and partly a very small clearance of several to several tens of micrometer level is maintained.

As the distance of the clearance formed on the clamping surface of the holder or the cutter and the cutting insert is larger and the area of the clamping surface formed with the clearance is widened, the cutting insert can not be stably fixed to the holder, The vibration and the working load are increased, and as a result, the life of the cutting insert is shortened. Particularly, in the cutting insert for machining a rough cutting material, the fastening force between the cutting insert and the holder or the cutter greatly affects the service life.

In addition, during cutting, the cutting insert has a high temperature due to a very high frictional heat. As the area where the clearance is formed becomes wider, the thermal conductivity generated by the cutting insert is lowered and the thermal load applied to the cutting insert increases. Or the end of the life of the cutting insert may be terminated sooner than before.

In order to solve such a problem, the generation of clearance on the clamping surface is minimized by precisely dimensioning the cutting insert. However, in the case of a mass-produced cutting insert, there is a limit to suppressing the occurrence of clearance.

As a means for preventing clearance, the following patent documents disclose a cutting insert detachably connected to a main body through a main body and an interface, wherein a geometric shape of the interface formed in the main body and the cutting insert is controlled, And to provide stable clamping force.

However, since such a tool has to be machined to a specific shape, a separate machining operation is required or a holder is required to be deformed, so that it is difficult to apply to various cutting inserts.

Korean Patent Publication No. 2009-0005008

According to the present invention, when fastened to a holder provided in a tool body, the fastening force is improved and the cutting operation is stably performed, and the frictional heat generated in the cutting insert for machining difficult-to-cut material can be quickly transmitted to the holder, Which can extend the service life of the cutting insert.

According to an aspect of the present invention, there is provided a cutting insert including an upper surface, a lower surface, a side connecting the upper surface and the lower surface, and a cut-in portion formed by the upper surface and the side surface, And a coupling assisting layer inserted or coated to cover a part or the whole of a coupling surface to be fastened to the holder of the tool body, wherein the coupling assisting layer is formed on the base material of the base material constituting the cutting insert or on the base material of the cutting insert The hard insert is made of a material having at least one of low hardness, good ductility, high thermal conductivity and excellent plastic deformation, compared with the hard film to be formed, and the cutting insert is fastened to the holder The fastening assisting layer is elastically deformed or plastic deformed, and the contact area between the cutting insert and the holder of the tool body Wherein the cutting insert is a ceramic insert or a cBN insert.

The cutting insert for machining a hard cutting material according to the present invention is characterized in that at least a part of a joint surface to be fastened to a holder of a tool body has a hardness lower than that of a cutting insert and a holder or a material having a high elasticity, The elastic layer or the plastic deformed material increases the contact area between the cutting insert and the holder and reduces the clearance to improve the clamping force, thereby reducing the machining load during the cutting process .

Further, since the coating layer or the insert layer is made of a material having a higher thermal conductivity than the cutting insert, the thermal conductivity is improved along with the enlargement of the fastening area, and the frictional heat generated at the cutting is quickly transferred from the cutting insert to the tool body So that the heat load can be reduced.

Particularly, in the case of ceramics used for machining hard materials, when the technical idea of the present invention is applied, the cutting performance is remarkably improved by improving the high-speed machining load fluctuation and thermal conductivity, and in the case of the cBN insert, So that a great effect can be obtained in maintaining the machining dimension.

1 is a photograph of Example 1 in which a coupling assisting layer is inserted into a C type ceramic insert and Comparative Example 1 in which a coupling assisting layer is not inserted.
Fig. 2 shows the result of qualitatively evaluating the joint area and the strength after fastening Example 1 in which the fastening assisting layer was inserted into the C-type ceramic insert and Comparative Example 1 in which the fastening assisting layer was not inserted.
Fig. 3 shows an enlarged view of the outer joint surface and an analysis result of the surface roughness state of Example 1 in which a coupling assisting layer was inserted into a C-type ceramic insert and Comparative Example 1 in which a coupling assisting layer was not inserted.
4 is a photograph of Example 2 in which a fastening assisting layer is inserted into an R type ceramic insert and Comparative Example 2 in which a fastening assisting layer is not inserted.
Fig. 5 shows the result of qualitatively evaluating the joint area and strength after securing Example 2 in which a coupling assisting layer was inserted into a R type ceramic insert and Comparative Example 2 in which a coupling assisting layer was not inserted.
6 is an enlarged view of the external engaging surface and an analysis result of the surface roughness state of Example 2 in which a coupling assisting layer was inserted into an R type ceramic insert and Comparative Example 2 in which a coupling assisting layer was not inserted.
Fig. 7 is a photograph of Example 3 in which a fastening assisting layer is inserted into a cBN insert and Comparative Example 3 in which a fastening assisting layer is not inserted. Fig.
Fig. 8 shows the result of qualitatively evaluating the joint area and strength of the cBN ceramics insert after fastening Example 3 in which the fastening assisting layer was inserted and Comparative Example 3 in which the fastening assisting layer was not inserted, to the holder.
Fig. 9 shows an enlarged view of the external engaging surface and an analysis result of the surface roughness state of Example 3 in which a fastening assisting layer was inserted into a cBN insert and Comparative Example 3 in which no fastening assisting layer was inserted.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the following embodiments of the present invention may be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art.

The cutting insert according to the present invention includes a cutting insert having a top surface, a bottom surface, a side connecting the top surface and the bottom surface, and a picked portion formed by the top surface and the side surface, And a fastening assisting layer formed to be inserted or coated so as to cover a part or all of the fastening surfaces to be fastened to the cutting insert, wherein the fastening assisting layer is formed on the hard coating formed on the surface of the base material of the cutting insert or the base material of the cutting insert Is made of a material having at least one of low hardness, good ductility, high thermal conductivity, and excellent plastic deformation property, and when the cutting insert is fastened to the holder, the fastening assistant Layer is elastically deformed or plasticized to increase the contact area between the cutting insert and the holder of the tool body, Grinding the insert is characterized in that a ceramic insert or cBN insert.

In the present invention, the term 'ceramic insert' refers to an insert made of ceramics whose main component is aluminum oxide as a main component. Ceramics include oxidized ceramics, ceramic composites, whisker reinforced ceramics, silicon nitride ceramics, sialon ceramics and the like.

Also, in the present invention, the 'cBN insert' may be formed by mixing a binder (metal / ceramic) and a boron nitride modified to a diamond-like structure (Cubic) in a hexagonal structure at a high temperature ), And a sintered body obtained by sintering under a high pressure (for example, 4 GPa or more) (preferably, an insert brazed to the insert portion of the insert).

Further, in the present invention, the term " holder of the tool body " is a term encompassing a portion where a cutting surface of a cutting insert is provided with various types of indexable tools used by fastening an insert to fasten the cutting insert, It is not a concept specific to a particular tool.

Further, in the present invention, the 'hard film' may be a single layer or a multi-layer structure including a metal compound such as an oxide, a carbide, a nitride, a carbonitride, and a carbonitride.

In the present invention, the fastening assisting layer is not particularly limited as long as it has the above-mentioned characteristics, and may be formed in the form of solid or semi-solid. For example, aluminum, copper, It can be made of a material excellent in plastic deformation and ductility and excellent in thermal conductivity.

Further, in the present invention, the fastening assisting layer may have a structure in which the fastening assisting layer is inserted. In this case, the fastening assisting layer may be inserted into one side of the cutting insert, and then inserted and reused after being detached.

Further, in the present invention, the fastening assisting layer may be formed by applying a composition containing an organic substance.

In the present invention, when the thickness of the fastening assisting layer is less than 1 탆, the above-mentioned effects such as the improvement of the fastening force or the thermal conductivity are not sufficient. If the thickness exceeds 500 탆, the tolerance range between the cutting insert and the holder is exceeded It may cause a problem in the cutting process, and therefore, it is preferably 1 to 500 mu m.

[Example 1]

In Example 1, a fastening assisting layer made of an aluminum foil having a thickness of about 60 탆 was inserted into a C-type ceramic insert manufactured by the model number of CNMA 120408 of Korea Metallurgy Co., Ltd.

As shown in FIG. 1, in the case of the cutting insert according to the first embodiment, a coupling assistant layer is formed so as to cover both the lower surface and the side surface excluding the upper surface.

Meanwhile, in the first embodiment of the present invention, the coupling assisting layer in the form of being covered on the lower surface and the side surface of the insert is used, but a coupling assisting layer in which at least a part of the coupling surface is covered or all coupling surfaces are covered can be used.

In the first embodiment of the present invention, a separate insert-type fastening assisting layer is applied to the cutting insert, but it is also possible to form a coating layer of several to several hundred micrometers in thickness on the fastening surface with the tool holder, for example, At this time, the formation of the coating layer may be performed by various methods such as a general thin film forming process and a printing process.

In addition, when the fastening assisting layer is formed by a coating method that is not an insertable / detachable form, a material having fluidity and adhesion such as a paste containing an organic material is applied to all or a part of the fastening surface of the cutting insert to a predetermined thickness May be formed.

Further, the insertion-type fastening assisting layer may be separated from the cutting insert and inserted into another side for reuse when the cutting edge of one side of the cutting insert is used.

Fig. 2 is a graph showing the results of evaluating the fastening area and the strength of the c-type ceramic insert after fixing the fastening assisting layer to the C-type ceramic insert in Example 1 and the holder (PCLNL2525-M12) The results are shown.

The qualitative evaluation was carried out in such a manner that a sheet whose color was changed by the pressure applied between the ceramic insert and the holder was inserted and fastened, and the color change of the sheet after the fastening was observed.

As can be seen in FIG. 2, it can be seen that the area of the lower surface and the side surface in contact with the holder of Example 1 is wider and the color is darker and the fastening force is better than that of Comparative Example 1.

Fig. 3 shows an enlarged view of the outer joint surface and an analysis result of the surface roughness state of Example 1 in which a coupling assisting layer was inserted into a C-type ceramic insert and Comparative Example 1 in which a coupling assisting layer was not inserted.

In FIG. 3, as in FIG. 2, it can be seen that the cutting insert having the fastening assisting layer inserted therein according to the first embodiment of the present invention has an area plastically deformed at the fastening surface compared to the cutting insert without the fastening.

[Example 2]

As shown in Fig. 4, Example 2 is a insert of a fastening assisting layer made of an aluminum foil having a thickness of about 60 탆 which covers a lower surface and a side surface of an R-type ceramic insert manufactured by the model number of RNGN120700 of Korea Metallurgy Co., .

Fig. 5 shows the result of qualitatively evaluating the joint area and strength after coupling Example 2 in which a coupling assisting layer was inserted into a R type ceramic insert and Comparative Example 2 in which a coupling assisting layer was not inserted, to the holder (CRSNL2525M12) .

As can be seen from Fig. 5, the area of the lower surface in contact with the holder of Example 2 is wider and the color is darker and the fastening force is better than that of Comparative Example 2. [

6 is an enlarged view of the external engaging surface and an analysis result of the surface roughness state of Example 2 in which a coupling assisting layer was inserted into an R type ceramic insert and Comparative Example 2 in which a coupling assisting layer was not inserted.

In FIG. 6, as in FIG. 5, it can be seen that the cutting insert having the fastening assisting layer inserted therein according to the second embodiment of the present invention has an increased area plastically deformed at the fastening surface compared to the other cutting inserts.

[Example 3]

As shown in Fig. 7, Example 3 was prepared by inserting a fastening assisting layer made of an aluminum foil having a thickness of about 60 占 퐉 to cover the lower surface and the side surface of a cBN insert manufactured by the model number CNMA120408 of Korea Metallurgy Co., Ltd.

8 shows the result of qualitatively evaluating the fastening area and strength after fastening Example 3 in which the fastening assisting layer was inserted into the cBN insert and Comparative Example 3 in which the fastening assisting layer was not inserted to the holder (PCLNL2525-M12) .

As can be seen from FIG. 8, the area of the lower surface and the side surface in contact with the holder of Example 3 was wider and the color became darker and the fastening force was improved, as compared with Comparative Example 3.

Fig. 9 shows an enlarged view of the external engaging surface and an analysis result of the surface roughness state of Example 3 in which a fastening assisting layer was inserted into a cBN insert and Comparative Example 3 in which no fastening assisting layer was inserted.

In FIG. 9, it can be seen that the cutting insert having the fastening assisting layer inserted therein according to the third embodiment of the present invention has a larger plastic deformed area at the fastening surface than the other cutting inserts.

Cutting performance evaluation

According to Examples 1 to 3 of the present invention, the cutting insert having the fastening assisting layer and the cutting insert without the fastening assisting layer (Comparative Examples 1 to 3) were fastened to the holder, and then the cutting insert was subjected to cutting, The service life was evaluated.

The cutting conditions according to Examples 1 to 3 were each performed under the conditions shown in Table 1 below.

Example 1 Example 2 Example 3 Workpiece INCONEL 718 (HRC40) Ф100 INCONEL 718 (HRC40) Ф100 INCONEL 718 (HRC40) Ф100 Cutting speed 250m / min 250m / min 120m / min transfer 0.2mm / rev 0.2mm / rev 0.2mm / rev Infeed 2mm 2mm 0.5mm system deflation deflation Wet

Table 2 below shows the results of the cutting tests performed under the conditions of Table 1.

division Total chip removal
(Cm 3) End tendency life span
(min) Overall Life Comparative Example 1 100.0 Sudden breakage One 100% Example 1 133.3 Boundary chipping 1.33 133% Comparative Example 2 200.0 Sudden breakage 2 100% Example 2 250.0 Abrasive wear 2.5 125% Comparative Example 3 120.0 Chipping, breakage 10 100% Example 3 144.0 Boundary chipping 12 120%

As shown in Table 2, in Comparative Examples 1 to 3, chipping phenomenon occurred during processing, chipping and breakage of the cutting edge frequently occurred, and the service life was terminated.

On the other hand, in Examples 1 to 3 of the present invention, the lifetime (total chip removal amount) increases as the fastening force is improved by the fastening assisting layer and the thermal load is reduced, and the lifetime is ended by boundary chipping.

In other words, the machining life of the cutting insert having the same base material and hard coating was extended by 20 to 30% through the fastening auxiliary layer applied according to Examples 1 to 3 of the present invention, This can be attributed to the load reduction.

Claims (4)

1. A cutting insert comprising an upper surface, a lower surface, a side connecting the upper surface and the lower surface, and a pick-up portion formed by the upper surface and the side surface,
Wherein the cutting insert has an outermost surface provided with a fastening auxiliary layer inserted or coated so as to cover a part or all of a fastening surface to be fastened to a holder of a tool body,
The fastening assisting layer has a lower hardness, a higher ductility, a higher thermal conductivity and a higher plastic deformation than the hard coating formed on the base material of the cutting insert or the base material of the cutting insert. Comprising a material having at least one characteristic,
Wherein when the cutting insert is fastened to the holder, the fastening assisting layer is elastically deformed or plasticized to increase the contact area between the cutting insert and the holder of the tool body,
Wherein the cutting insert is a ceramic insert or a cBN insert. The method according to claim 1,
Wherein the fastening assisting layer is made of aluminum, copper, or an alloy thereof. The method according to claim 1,
Wherein the fastening assisting layer is formed by application of a composition comprising an organic material. The method according to claim 1,
Wherein a thickness of the fastening assisting layer is 1 to 500 μm.

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