JPH04310325A - Manufacture of hard film covered high speed steel - Google Patents

Abstract

PURPOSE:To manufacture a high speed steel cutting tool having an edge part covered with a hard film on a cutting edge having no grinding burr and whose edge tip is sharp easily and stably. CONSTITUTION:A TiN film 16 is covered by a PVD method after executing the finishing grinding of a rake face 14 as well as executing the rough grinding of the flank 18 of a cutting edge 12 made of a high speed steel, thereafter, a TiC film 20 is coated by the PVD method with the finishing grinding of the flank 18 being executed.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for manufacturing a cutting tool having a cutting edge made of high-speed steel whose surface is coated with a hard film, and in particular, the present invention relates to a method of manufacturing a cutting tool having a cutting edge made of high-speed steel and having a hard film coated on the surface thereof, and in particular, a cutting tool having a sharp cutting edge without grinding burrs. This invention relates to a method of coating a blade with a hard film.

0002

[Prior art] TiC or T on the surface of a high-speed steel cutting edge.
A cutting tool having a blade portion coated with a hard film such as iN is disclosed in, for example, JP-A-61-274808 and JP-A-62-2.
It is disclosed in Publication No. 0863 and the like. This kind of hard film coating is usually done after finishing the cutting edge of high-speed steel by grinding, but it is inevitable that grinding burrs will occur on the finished cutting edge, and this burr Not only is this harmful to sharpness, finished surface roughness, and chipping resistance, but when a hard film is coated as is by PVD or the like, it impedes its throwing power and further deteriorates chipping resistance. For this reason, before coating with a hard film, deburring is performed by shot blasting using various abrasive materials and projectile materials, brushing, manual work, etc. 6 and 7 are diagrams specifically showing the above-mentioned grinding burr, and the grinding burr 108 in FIG.
The grinding burr 110 in FIG. 7 is generated on the cutting edge 106 when the flank surface 104 is finished by grinding after the flank surface 104 is finished by grinding.The grinding burr 110 in FIG. This occurred in Such grinding burrs 108, 110 are usually
The thickness t of the root is approximately 0.02 to 0.1 mm.

0003

[Problems to be Solved by the Invention] However, in deburring the cutting edge, apart from removing a large chamfer, there is a large variation when trying to obtain a sharp cutting edge, and it is difficult to stably maintain a sharp cutting edge. It was difficult to form. FIG. 8 is a diagram showing an example of the shape of the cutting edge after deburring the grinding burr 108 of the cutting edge 100 shown in FIG.
b is a case where a part of the grinding burr 108 is left behind;
The cutting edge 106c in (c) is a case where a part of the grinding burr 108 is left behind and the tip is scraped off, and (d)
The cutting edge 106d has no remaining grinding burr 108, but the tip has been largely shaved off and becomes flat. For example, a hard film 112 is attached to the cutting edge 100 in FIG. 8(a).
When the hard film 112 is coated, it becomes as shown in FIG. 9(a).
It has poor coverage and early chipping and wear, resulting in short life and unfavorable finished surface roughness. In addition, a hard film 112 is attached to the cutting edge 100 in FIG. 8(d).
If it is coated, the result will be as shown in FIG. 9(b), and it will not have sharpness and have poor cutting quality and finished surface roughness, will easily generate cutting heat, and will have a short life.

The present invention was made against the background of the above-mentioned circumstances, and its object is to provide a high-speed steel having a cutting edge with a sharp cutting edge coated with a hard film and free of grinding burrs. The goal is to make cutting tools stable and easy to manufacture.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a method for manufacturing a cutting tool having a cutting edge made of high-speed steel whose surface is coated with a hard film, comprising:
a) a first grinding step of grinding the flank and rake surfaces of the cutting edge made of high-speed steel; and (b) a first step of coating the flank and rake surfaces ground by the first grinding step with a hard film. a hard film coating step; (c) a second grinding step of grinding either the flank face or the rake face after the first hard film coating step; and (d) a second grinding step of grinding either the flank face or the rake face after the second grinding step. It is characterized by comprising a second hard film coating step of coating the face and the rake face with a hard film.

[0006]

[Operations and Effects of the Invention] That is, in the manufacturing method of the present invention, first, in the first grinding step, the flank face and rake face of the cutting edge made of high speed steel are ground. At this time, as shown in FIGS. 6 and 7, the cutting edge has a rake surface on the surface that was not the last ground surface, that is, when the flank surface was ground last, there is a rake surface on the rake surface side. When the surface is ground last, grinding burrs are generated on the flank side, but these flank and rake faces are coated with a hard film in the next first hard film coating step.

[0007] Thereafter, in a second grinding step, either the flank face or the rake face is ground. In this second grinding step, since the flank and rake surfaces are coated with a hard film in the first hard film coating step, grinding burrs will not be pushed out to the other surface even if either surface is ground. Grinding burrs can be effectively avoided by removing grinding burrs by grinding the surface on which grinding burrs were generated in the first grinding process, that is, the surface that was not the last surface ground in the first grinding process. A sharp cutting edge is formed.

After the second grinding step, the flank and rake surfaces of the cutting edge are again coated with a hard film in the second hard film coating step, thereby creating a cutting edge with no grinding burrs and a sharp cutting edge. A cutting tool having a blade portion covered with a hard film is obtained.

As described above, the manufacturing method of the present invention performs the final grinding process after coating the hard film to remove grinding burrs, and then coats the hard film again, thereby eliminating the trouble of shot blasting etc. A high-speed steel cutting tool that does not require extensive deburring work, has no grinding burrs, and has a sharp cutting edge coated with a hard film can be stably and easily manufactured.

[0010] Furthermore, since either the flank face or the rake face is coated with the hard film twice, the first hard film coating step and the second By coating hard films of different materials in the second hard film coating step, wear resistance can be significantly improved. This, in combination with the ability to form a sharp cutting edge without grinding burrs as mentioned above, makes it possible to perform finish cutting and high-speed cutting of difficult-to-cut materials that generate high cutting heat and are prone to work hardening. can be performed effectively with long tool life.

In general, the rake face comes into contact with chips and causes rake face wear, or crater wear, while the flank face comes into contact with the workpiece, causing flank wear, or flank wear. Because the cutting temperature and stress are different, crater wear and flank wear have different wear characteristics, with crater wear having more wear due to heat generation and flank wear having more wear due to friction distance. Therefore, the rake face is coated with a hard film such as TiN that has excellent wear resistance at high temperatures, while the flank face is coated with a hard film such as TiC that has excellent wear resistance at low temperatures. By doing so, the wear resistance on the rake face and flank face can be effectively improved. Specifically, for example, when grinding the flank face in the second grinding process, the first hard film coating process covers the flank with a hard film that has excellent wear resistance at high temperatures, and the second hard film coating process coats the flank with a hard film that has excellent wear resistance at low temperatures. If the rake face is coated with a hard film that has excellent wear resistance at A hard film is coated to effectively prevent flank wear. When grinding the rake face in the second grinding process, the first hard film coating process coats the rake face with a hard film that has excellent wear resistance at low temperatures, and the second hard film coating process coats it with a hard film that has excellent wear resistance at high temperatures. It is only necessary to cover it with an excellent hard film.

[0012] In order to deal with the various wear mechanisms of cutting tools, it has been conventionally practiced to coat cutting tools with multiple layers of hard films made of different materials, but even if the thickness of each layer is thin, the total The film thickness inevitably increases, which reduces toughness and makes the blade more likely to chip, and it is difficult to apply it to milling cutters, reamers, taps, etc. for finishing cutting that require sharp cutting edges. be. In contrast, in the method of the present invention, the hard film on either the flank face or the rake face is removed in the second grinding process, so the sharpness of the cutting edge is maintained and multiple types of hard films are coated. Is possible. In each of the first hard film coating step and the second hard film coating step, a plurality of types of hard films can be coated.

On the other hand, the first hard film coating step and the second
Various methods such as PVD and CVD can be used to coat the hard film in the hard film coating process, but P, which can be coated at a temperature below the appropriate tempering temperature of high-speed steel,
According to the VD method, a cutting tool with high dimensional accuracy can be obtained without causing large deformation of high-speed steel.

[0014] Furthermore, the relief surface of the cutting edge is not necessarily limited to a surface with a relief angle, but is also a concept that includes a margin without a relief angle.

[0015] Furthermore, it is of course possible to insert processes such as light deburring and cleaning as appropriate during or between the above steps.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a diagram illustrating the configuration of the blade portion 10 of a hard film-coated high-speed steel cutting tool manufactured according to the method of the present invention.
The iN film 16 is coated, and the TiN film 1
6 and flank surface 18 are coated with a TiC film 20. Both the TiN film 16 and the TiC film 20 are hard films, and the TiN film 16 has a hardness Hv of 1950 to 2100.
It has good throwing power and adhesion, as well as excellent chipping resistance, and is especially resistant to crater wear due to its high high temperature hardness. Further, the TiC film 20 has a hardness Hv of 3000 to 3200.
Extremely hard and resistant to flank wear. However, this TiC
The film 20 has relatively low hardness at high temperatures.

FIG. 2 is a diagram illustrating the machining process of the blade portion 10. First, as shown in (a), the flank surface 18 of the cutting edge 12 is roughly ground, and as shown in (b), the flank surface 18 of the cutting edge 12 is roughly ground. Finish grind the rake face 14 as shown. These steps are the first grinding step, and in this state, grinding burrs 22 are present on the flank surface 18. Next, as shown in (c), the rake face 14 and flank face 18 of the cutting edge 12 where the grinding burr 22 still exists are properly tempered using the PVD method. The TiN film 16 is coated at a temperature below the return temperature. This step (c) is the first hard film coating step.

Thereafter, as shown in (d), the surface of the rake face 14 and the flank surface 18 that is not the last surface ground in the first grinding process, that is, the rake face in the process of (b) 14 has been finish ground, so the flank face 18 is finish ground. At this time, since the rake face 14 and flank face 18 are coated with the TiN film 16,
Even if finish grinding is performed on the flank surface 18, grinding burrs are effectively prevented from being pushed out to the rake surface 14 side, and the above (b)
By removing the grinding burrs 22 generated in step ), a sharp cutting edge without burrs is formed. This process is the second
This is a grinding process.

Finally, as shown in (e), the cutting edge 12 is formed by the PVD method on the TiN film 16 on the flank face 18 and rake face 14 that have been finished ground in the second grinding step. By coating the TiC film 20 at a temperature below the appropriate tempering temperature of the high-speed steel that constitutes the blade portion 1.
0 is obtained.

According to such a processing method, there is no need for troublesome deburring work such as shot blasting, and the cutting edge 12 is free from grinding burrs and has a sharp cutting edge, and the blade portion 10 is coated with a hard film. cutting tools can be stably and easily produced.

Further, the rake face 14 is coated with a TiN film 16 and a TiC film 20, while the flank face 18 is coated with a TiC film 16 and a TiC film 20.
Since the film 20 is coated, crater wear on the rake face 14 is well prevented by the TiN film 16, and flank wear on the flank face 18 is well prevented by the TiC film 20. As a result, the blade portion 10 with no grinding burrs and a sharp cutting edge can be obtained as described above, and it is also possible to finish cutting difficult-to-cut materials that easily generate high cutting heat or harden due to work. High-speed cutting can be performed successfully with long tool life.

[0023] Furthermore, the TiN film 16 and the TiC film 2
Since the coating of 0 is performed by the PVD method at a temperature below the appropriate tempering temperature of the high-speed steel that constitutes the cutting edge 12, the cutting edge 12 is not significantly deformed and the cutting edge 10 has high dimensional accuracy. There is an advantage of being able to obtain

Note that in the above example, the TiN film 1 is formed on the rake surface 14.
6 and TiC film 20 are coated, and the flank surface 18 is coated with TiC film 20.
Although the blade portion 10 covered with the membrane 20 has been described, FIG.
As shown in the blade portion 30 shown in FIG.
It is also possible to coat the film 20 and the TiN film 16 so that the rake face 14 is coated with the TiN film 16. In that case, as shown in FIG. 4, the rake face 14 is roughly ground in (a), the flank face 18 is finished in (b), and the TiC film 20 is coated with PVD in (c). The rake face 14 is coated by finishing grinding in (d), and (e
) may be used to cover the TiN film 16. In this case as well, the same effects as in the above embodiment can be obtained.

Next, the results of a performance test regarding tool life using the following cutting tools will be explained.

Cutting tool Type: Tapered end mill, 2 flutes, square end Dimensions: Tip diameter 10 mm, slope 3°, blade length 3
0mm Grade: High speed steel AISI-M43, HR
C68 Hard film: Inventive product...TiN film coated with a thickness of 2 μm by PVD method
→Flank surface grinding 8μm
→PV
TiC film coating with a thickness of 2 μm using D method
Conventional product I: Deburring by blasting

→2μm thick TiN film coating by PVD method
→2μm thick TiC film coating by PVD method
Conventional product II: Deburring by blasting
→
TiCN film coating with a thickness of 4 μm by PVD method
Uncoated product: No hard film

Cutting conditions Work material: Stainless steel JIS-304, HRB88
Rotation speed: 1000 rpm Cutting width: 25 mm Depth of cut: 1.0 mm Feed rate: 200 mm/min Cutting oil: Sulfurated water-insoluble cutting oil Cutting method: Up-cut machine: Vertical machining center

FIG. 5 shows the results of measuring the cutting length while setting the tool life to a maximum wear width of 0.3 mm on the peripheral edge flank face or until the occurrence of edge chipping or breakage. From this result, it can be seen that the product of the present invention can obtain a tool life approximately twice as long as that of conventional products I and II. Note that the TiCN film coated on Conventional Product II has properties approximately intermediate between those of the TiN film and the TiC film.

Although the embodiments of the present invention have been described above in detail based on the drawings, these are just one specific example.
For example, the present invention may be modified by changing the material or coating method of the hard film, by coating the same hard film in two hard film coating processes, or by applying the present invention to cutting tools other than end mills. can be implemented with various changes and improvements based on the knowledge of those skilled in the art.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating the structure of a blade portion of a cutting tool manufactured according to the method of the present invention.

FIG. 2 is a diagram illustrating the machining process of the blade portion in FIG. 1;

FIG. 3 is a diagram illustrating the structure of the blade portion of another cutting tool manufactured according to the method of the present invention.

4 is a diagram illustrating a machining process for the blade portion of FIG. 3. FIG.

FIG. 5 is a diagram showing the results of a performance test regarding tool life using a cutting tool manufactured according to the method of the present invention and a conventional cutting tool.

FIG. 6 is a diagram illustrating grinding burrs present on the cutting edge after grinding.

FIG. 7 is a diagram illustrating another aspect of grinding burrs present on the cutting edge after grinding.

FIG. 8 is a diagram illustrating various forms after deburring the cutting edge of FIG. 6;

9 is a diagram showing an example of a blade portion of a conventional cutting tool in which the cutting edge of FIG. 8 is coated with a hard film.

[Explanation of symbols]

10, 30: Blade part 12: Cutting edge 14: Rake face 16: TiN film (hard film) 18: Relief surface 20: TiC film (hard film)

Claims (2)

[Claims] 1. A method for manufacturing a cutting tool having a cutting edge made of high-speed steel whose surface is coated with a hard film, the method comprising: grinding a flank face and a rake face of the cutting edge made of high-speed steel; a first grinding step, a first hard film coating step of coating the flank face and rake face ground by the first grinding step with a hard film, and after the first hard film coating step, the flank face and the rake face are a second grinding step of grinding either one of the
A method for manufacturing a hard film-coated high-speed steel cutting tool, comprising a second hard film coating step of coating the flank and rake faces with a hard film after the second grinding step. 2. The method for manufacturing a hard film-coated high-speed steel cutting tool according to claim 1, wherein the first hard film coating step and the second hard film coating step coat hard films of different materials.