JP5327740B2 - Cutting tip - Google Patents

Description

  The present invention relates to a cutting tip that reduces the amount of tungsten used and has a long life.

  When processing automobile parts and the like, a cutting tool using a cemented carbide having a high melting point and a small decrease in hardness even at high temperatures is generally used. Here, the cemented carbide is an alloy mainly composed of tungsten carbide (WC) and cobalt (Co), and cutting tools using the cemented carbide account for more than half of the production value. As a form of the cutting tool using the cemented carbide, there are a tip attached to the tip of a bite holder or the like, a drill and the like.

  FIG. 4 is a view showing a conventional cemented carbide chip attached to a bite holder. When machining stainless steel, alloy steel, or the like, the cemented carbide tip 11 is attached to the bite holder 12 and the work piece is rotated to perform peripheral processing at the tip of the cemented carbide tip 11.

  As described above, the cemented carbide contains tungsten as a main component. It has been pointed out that tungsten, the main raw material for cutting tools using cemented carbide, is a rare metal that is difficult to secure in the future. Therefore, the development of materials to replace cemented carbide and the technology for reducing the amount of use are being promoted.

  However, as shown in FIG. 4, a generally used cutting tip is made of the same material in the vicinity of the cutting edge at the tip of the tip and a portion that does not come into contact with other work materials. On the other hand, cutting tips coated with ceramics such as nitride on cemented carbide may be used, but the vicinity of the cutting edge at the tip of the tip and the other parts are the same material. , Essentially the same. In addition, if a cemented carbide with high wear resistance that can withstand high stress and heat generated by contact with chips on the rake face side of the cutting tip is used, the wear on the tool flank will increase. As a result, the frictional force is increased on the flank side of the cutting tip, which causes further heat generation.

  As a technique for suppressing heat generation at the cutting edge portion of the cutting tip, a cutting tip made of a material having a laminated structure or a functionally inclined structure has been proposed (for example, see Patent Document 1). Also known is a cutting tip in which a super-hard sintered body containing cubic boron nitride (hereinafter referred to as cBN) having excellent thermal conductivity and a cemented carbide are laminated (for example, , See Patent Document 2).

JP-A-10-156605 JP-A-8-33213

  However, in the technique described in Patent Document 1, it is possible to suppress the temperature rise of the cutting edge of the cutting tip by combining the cemented carbide material (WC) and copper having high thermal conductivity into a gradient composition. However, an increase in cutting resistance due to an increase in tool flank wear could not be suppressed.

  Moreover, in the technique of the said patent document 2, from a viewpoint that the cost which manufactures the ultra-high-hardness sintered compact containing cBN requires much, the ultra-high-hardness sintered body containing cBN only in the part which contacts a work material Is used. Therefore, an increase in cutting resistance due to an increase in tool flank wear could not be suppressed.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a cutting tip capable of reducing the amount of tungsten used and suppressing cutting resistance associated with increased tool flank wear.

The cutting tip of the present invention is a cutting tip that can be attached to and detached from a tool holder, the rake face layer is made of a cemented carbide having a thickness of 0.1 mm to 0.6 mm, and the rake face The layer adjacent to the side layer is made of molybdenum high speed steel .

  According to the present invention, since the cemented carbide having a high tungsten content is used only on the surface side of the rake face, the amount of tungsten used can be suppressed. Moreover, since the adjacent layer is an alloy having lower wear resistance than the cemented carbide, the cutting resistance when the flank is worn can be reduced. Thereby, a tool life can be improved.

  The inventor believes that the part where the tool contacts the workpiece in cutting is a narrow part close to the cutting edge, and that the tool life is caused by an increase in cutting resistance (cutting heat) caused by wear on the flank. As a result of diligent investigation, we found a two-layer cutting tip composed of a cemented carbide thin plate and a molybdenum-based high-speed steel base material.

FIG. 1 is a diagram illustrating a structure example of a cutting tip 1 according to the present embodiment.
In FIG. 1, a cemented carbide thin plate 2 is formed on the surface side of the rake face of the cutting tip 1, and a molybdenum base high-speed steel is used for the lower base material 3. The thin plate 2 and the base material 3 are joined by brazing using a silver braze or the like. In addition, when performing cutting, the cutting tip 1 is attached to the tool holder 4 or the like.

  The cemented carbide used for the thin plate 2 on the surface side of the rake face is characterized by excellent wear resistance, high hardness, and small decrease in hardness even when the cutting edge temperature is increased by cutting. On the other hand, the molybdenum-based high speed steel used for the base material 3 is characterized by excellent heat resistance and rigidity. Since strength is required on the side of the rake face that contacts with the work material and generates chips, a cemented carbide thin plate 2 having excellent strength is joined to the upper part. On the other hand, when the wear resistance increases, the cutting resistance increases at the contact surface between the worn portion of the flank and the work material, and therefore, the high-speed steel having low wear resistance is joined to the lower portion as the base material 3. Yes. Thereby, when the base material 3 is exposed to the flank wear part, since the base material 3 has low wear resistance, an increase in cutting resistance can be suppressed.

FIG. 2 is a diagram illustrating a state in which a work material is being cut using the cutting tip 1 according to the present embodiment. As shown in FIG. 2, when the work material is cut, the main component force F _z is mainly received from the cutting material on the rake face side, and the back force force F _y is mainly applied from the work material on the flank side. Receive. When the flank wear amount V _B increases, the high speed steel as the base material 3 is exposed at the flank wear portion. In a state where the high-speed steel is exposed, the high-speed steel as the base material 3 has low wear resistance at high temperatures, so that the base material portion is greatly worn and retracted. As a result, part of the base material 3, since the cutting resistance becomes small resulting in some parts thereof are either not in contact with the workpiece, or contact with, the portion is substantially subjected to the back component force F _y is a cemented carbide It becomes only the part of. Accordingly, the cutting resistance is kept constant, and the tool life is improved.

FIG. 3 is a diagram showing the relationship between the flank wear width and the cutting resistance. A broken line 6 in FIG. 3 indicates a tool flank wear width. In addition, the cutting resistance of the cutting tip 1 having the two-layer structure shown by the solid line 7 increases with the wear of the flank, but when the flank wear width becomes larger than the thickness of the surface thin plate, the cutting resistance Is kept constant. When the work surface of the work material and the rake surface of the cutting tip 1 are perpendicular as in the example shown in FIG. 2, if the flank wear amount V _B exceeds the thickness of the cemented carbide thin plate 2, The base material 3 is exposed at the flank wear portion. In the state where the high-speed steel that is the base material 3 is exposed, the portion that receives the cutting resistance is only the cemented carbide portion as described above. Therefore, in the case of the cutting tip 1 having a two-layer structure, the cutting resistance is It is kept almost constant. On the other hand, the cutting resistance of the conventional carbide tip indicated by the dotted line 8 continues to increase as the flank wear increases.

As described above, the cutting tip 1 having a two-layer structure can reduce the amount of cemented carbide to be used as compared to a conventional single-layered tip made of cemented carbide, and the flank wear amount V. _{Even if B} increases, the cutting force can be kept almost constant. Thereby, cutting resistance becomes small compared with the chip | tip of the cemented carbide of the conventional single layer structure, and tool life can be lengthened.

In the case of a cutting tip having a single-layer structure, if the flank wear amount V _B exceeds 0.6 mm, the cutting resistance becomes too large, causing chipping and blurring, and the function as a cutting tip can be maintained. Disappear. Therefore, in order to maintain a cutting resistance that does not cause chipping or blurring, it is preferable that the thickness of the thin plate 2 made of cemented carbide is 0.6 mm or less. Furthermore, in order to ensure the stable performance, it is preferable that it is 0.5 mm or less.

On the other hand, if the thickness of the thin plate 2 made of cemented carbide is less than 0.1 mm, the strength against the main component force F _y due to the chips cannot be secured sufficiently, and the manufacturing becomes very difficult. The thickness of the thin plate 2 made of a cemented carbide is preferably 0.1 mm or more.

  In the structural example shown in FIG. 1, a cemented carbide thin plate is formed only on one side of the cutting tip. On the other hand, in the case of a cutting tip having a shape in which the rake face and the flank face are vertical, a three-layer structure in which a cemented carbide thin plate is formed on the front surface and the back surface may be used. This makes it possible to use the front side and the back side at one corner.

Next, the cutting test result of the cutting tip 1 according to the present embodiment will be described.
FIG. 5 is a diagram showing the shape of the cutting edge portion of the apparatus and cutting tip used in the cutting test in this example.
The shape of the cutting tip used in this example is a two-layer structure of a 0.5 mm thick cemented carbide and a 5.5 mm thick high-speed steel as shown in FIG. In order to reduce the cutting resistance when increased, a chamfer honing of about 10 ° was provided at the tip portion, and the thickness of the cemented carbide at the tip portion was set to 0.2 mm. The rake angle was set to 6 ° and the clearance angle was set to 6 °. Detailed cutting conditions are as shown in Table 1 below.

  For comparison, a cutting chip having the same shape as the cutting chip manufactured in this example was also prepared for the cutting chip having a single layer structure using only the cemented carbide.

FIG. 6 is a photograph showing the wear pattern of the cutting edge portion after 1 minute and after 10 minutes when the work material is cut under the conditions of this example.
When the cemented carbide was M20, V = 209 m / min, and wet cutting, flank wear progressed greatly, but there was no large crater development on the rake face side.

FIG. 8 is a diagram showing the results of a cutting test using the cutting tips produced in this example. FIG. 8A shows the transition of the average flank wear width V _B and the maximum flank wear width V _BMAX , and FIG. 8B shows the back component force F _y and the main component force F _z . Shows the transition. Further, “Surface” and “base” respectively indicate the wear width of the cemented carbide and the wear width of the high-speed steel at the flank as shown in FIG. In FIG. 7, the entire end portion (flank) of the cemented carbide thin plate is worn, and the same level of wear (width) is also generated in the high-speed steel portion.

As shown in FIG. 8A, the single-layer cutting tip produced as a comparative example had a life of 4 to 5 minutes, whereas the two-layer cutting tip produced in this example Even at the stage of cutting for 10 minutes, the service life was not reached. Moreover, as shown in FIG.8 (b), it turns out that the back component force _Fy is large in the cutting tip of a comparative example in the stage after 4 minutes. Thus, the life of the cutting tip having a two-layer structure produced in this example was more than doubled as compared with a single-layer cutting tip produced as a comparative example, confirming its usefulness.

9-11 is a figure which shows the result of having performed the cutting test on other cutting conditions using the cutting tip produced in the present Example.
Similar to the results shown in FIG. 8, as shown in FIGS. 9 to 11, the two-layered cutting tip produced in this example was compared with the single-layer cutting tip produced as a comparative example. However, the service life was prolonged and the usefulness was confirmed.

  As described above, according to the present embodiment, the cutting resistance becomes less than a certain value even when the flank wears, and the tool life is prolonged, as compared with the conventional cutting tip having a single-layer structure made of cemented carbide.

It is a figure which shows the structural example of the chip | tip for cutting which concerns on embodiment of this invention. It is a figure which shows the state which is cutting the work material using the chip | tip for cutting which concerns on embodiment of this invention. In embodiment of this invention, it is a figure which shows the relationship between flank wear width and cutting resistance. It is a figure which shows the conventional cemented carbide chip attached to the bite holder. It is a figure which shows the shape of the blade edge | tip part of the apparatus and cutting tip which were used in the cutting test in the Example of this invention. It is a photograph which shows the abrasion form of the blade edge | tip part after 1 minute and 10 minutes when a work material is cut on the conditions of the Example of this invention. It is a photograph which shows the wear form by the side of a flank. It is a figure which shows the result of having performed the cutting test using the chip | tip for cutting produced in the Example of this invention. It is a figure which shows the result of having performed the cutting test on other cutting conditions using the cutting tip produced in the Example of this invention. It is a figure which shows the result of having performed the cutting test on other cutting conditions using the cutting tip produced in the Example of this invention. It is a figure which shows the result of having performed the cutting test on other cutting conditions using the cutting tip produced in the Example of this invention.

Explanation of symbols

1 Cutting tip 2 Thin plate 3 Base material 4 Tool holder 11 Cemented carbide tip 12 Tool holder

Claims (2)

A cutting tip that can be attached to and detached from a tool holder,
A cutting tip characterized in that a rake face side layer is made of a cemented carbide having a thickness of 0.1 mm to 0.6 mm, and a layer adjacent to the rake face side layer is made of molybdenum high speed steel . The cutting tip according to claim 1 , wherein the cutting tip has a two-layer structure of a layer made of the cemented carbide and a layer made of the molybdenum-based high speed steel .

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