JPS6256231B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a cutting tool whose surface is coated and made of high-speed tool steel, which has superior cutting durability even after re-grinding compared to conventionally used titanium alloy-coated cutting tools. When conventional titanium alloy-coated cutting tools are reground, the coating layer on the rake face (e.g., hob) or flank face (e.g., drill) is removed, so the wear on these parts is due to the wear resistance of the base material, high-speed tool steel. For example, in a hob, crater wear develops on the rake face, leading to destruction of the ridge line, that is, chipping wear. In the tool of the present invention, the high-speed tool steel that is the base material is made of ultra-high V and high Co components that can only be produced by powder metallurgy, so it has excellent heat resistance without sacrificing toughness and grindability. Because of its wear resistance, even after re-grinding, the wear on the re-ground surface is small, and even if the coating layer on the surface where the coating layer remains is worn away, it has the characteristics of being able to significantly stop the progress of wear. That is, the present invention provides cutting tools with C1.80 to 3.30% by weight, respectively. Si0.10~0.60%.
Mn0.10~0.60%. Mo3.0~5.0%. W7.0~11.0
%. Cr3.5~5.0%. Co7.0-10.0%. N0.005~0.3
%, one type of V.Nb.Ti or the sum of two or more types of these is 8.0 to 11.0%, and the balance is Fe.
and impurities, such as carbides, nitrides, or carbons of metals of Group A, Group A, or Group A of the Periodic Table, which are present on the surface of cutting tools made of powdered high-speed steel manufactured by powder metallurgy. Deposit one layer of nitride or alumina (Al ₂ O ₃ ), or two or more layers of any different kind, to reduce crater wear on the flank face or flank wear from which the coating layer has been removed after re-grinding the cutting tool. The present invention provides a coated cutting tool characterized by eliminating chipping wear on the cutting edge line. Next, the method for manufacturing the high-speed steel that forms the cutting tool of the present invention, that is, the steel of the present invention, and the reasons for limiting each component will be described. The method for producing the steel of the present invention is that when conventional melting methods are used with the ingredients of the steel of the present invention, huge vanadium carbides are formed, making it impossible to forge and roll a steel ingot.
Even if a tool is made using a casting method, cutting and grinding is not only extremely difficult for the same reason, but it also cannot have the toughness required for a cutting tool. However, when manufactured using the powder metallurgy method, the carbides are distributed finely and uniformly, so all forming processes can be performed in the same way as conventional high-speed tool steel, and the toughness is also JIS.
The product is not much different from SKH ₉ produced by the melting method. Therefore, the manufacturing method for the steel of the present invention is limited to powder metallurgy. C is an essential component for imparting sufficient hardness (H _R C65 to 69) to the steel of the present invention through heat treatment, but if its content is less than 1.80%, the hardness is insufficient; If the content exceeds C, hot plastic workability and toughness are impaired, so the content of C was set to 1.80 to 3.30%. Si and Mn were set at 0.1 to 0.6%, which is the range generally included as a deoxidizing agent. W.Mo is essential to provide wear resistance and heat resistance, but in the steel of the present invention, Co and V
By increasing the auxiliary effect of W.Mo, the balance of W.Mo was focused on toughness and hardenability. i.e. W7.0%
If it is less than 11.0%, the hardenability and heat resistance will decrease, and if it exceeds 11.0%, the toughness will decrease.
It was set at 11.0%. In addition, when Mo is less than 3.0%, W11% or more is required to provide sufficient heat resistance, and toughness is significantly reduced.If Mo exceeds 5.0% and W is 7% or less, hardenability and heat resistance deteriorate. descend. Sideways
Mo was limited to a range of 3.0 to 5.0%. Cr gives hardenability and tempering resistance, but 3.5
If it is less than 5%, the effect will be small, and if it is more than 5%, the toughness will be impaired, so the range is set to 3.5 to 5.0%. V.Nb and Ti combine with C to form Vc.Nbc or
TiC forms carbonized components, which significantly improves wear resistance. The most distinctive feature of the steel of the present invention is this
The sum of one or more types of V.Nb.Ti, i.e. (V+
This is because it contains a large amount of Nb+Ti).
A suitable balance with C suppresses the coarsening of austenite crystal grains and contributes to improving heat resistance without impairing hardenability. However, in the range of C mentioned above, if (V+Nb+Ti) is less than 8%, these effects will be small, and if it is more than 11%, the hardenability will be significantly impaired, so the range was set to 8.0 to 11.0%. The reason for limiting it to (V+Nb+Ti) is that the three have similar effects. Co dissolves in the matrix and improves heat resistance, but impairs toughness. That is, if it is less than 7%, the heat resistance is insufficient, and if it is more than 10%, the toughness is significantly reduced. Therefore, the range for Co was 7.0 to 10.0%. Although N is contained in trace amounts in both melting and powder metallurgy manufacturing methods, this material contains 0.005% N during manufacturing.
It is difficult to keep it below. In particular, for a tool material that promotes grain refinement and requires high toughness, N is preferably 0.03 to 0.3, so the content was limited to 0.005 to 0.3%, which includes both. Next, tools using the above materials are group a,
The reason why one layer or two or more optionally different layers of carbides, nitrides, or carbonitrides of group metals or group a metals and alumina (Al ₂ O ₃ ) are vapor-deposited will be described. The steel of the present invention contains a large amount of fine grain VC, NbC or TiC.
Contains carbide, which is the same group or similar group to the above-mentioned coating layer, and both have a face-centered cubic atomic arrangement, so epitaxial growth of the deposited layer progresses smoothly, improving adhesion and film density. The quality is also good. The above compounds have high hardness reaching HV1300 to 3800 depending on the type, and even with a deposition thickness of 1 to 5 μm, it is possible to secure a cutting length that is 2 to 20 times longer than normal cutting before reaching the same amount of wear. This is because chemical vapor deposition and physical vapor deposition methods, which have already been commercialized, can be easily applied. The reason for limiting the use of carbides and nitrides in each of the aaa groups is that they have different wear resistance and lubricity, and carbides are used for applications that are susceptible to abrasive wear, while nitrides are used for applications that are susceptible to adhesive wear. This is because it is effective to use different types of carbonitrides, and carbonitrides are limited as being intermediate between them. The reason for depositing two or more layers of arbitrary different types is, as mentioned above, that each compound has its own characteristics, and by laminating two or more layers, it is possible to not only obtain a synergistic effect, but also to improve the coefficient of thermal expansion with the base material. This is because the effect of preventing peeling of the non-adhesive layer is great in extreme cases of stress within the film due to differences in the amount of stress. The present invention is a cutting tool made of high-speed tool steel as defined above and subjected to a vapor deposition treatment.Next, the features will be illustrated with drawings and the advantages obtained by the present invention will be explained. In the figure, "Invention Steel N" is an example of a high-speed tool steel that forms the cutting tool of the present invention, and has the following chemical composition. C2.41%. Si0.36%. Mn0.37%. P0.021%.
S0.011%. Cr4.13%. Ni0.08%. Cn0.04%.
Mo3.21%. W9.90%. V8.73%. Co9.88%.
N0.0181% Figure 1 is a graph showing the high temperature hardness of "Invention Steel N" and JIS SKH _9. Figure 2 is a graph showing the high temperature hardness of "Invention Steel N" and SKH ₉ .
2 is a graph showing wear resistance according to the Ohkoshi rapid wear test method. In either case, "invention steel N" was not coated. The cutting wear resistance, which is a characteristic of the tool steel that forms the cutting tool of the present invention, was shown in comparison, but the JIS steel manufactured by the melting method
It is clearly superior to SKH ₉ .
In addition, Figure 3 similarly shows the bending test results of "Invention Steel N" which was not coated in the same way as in Figures 1 and 2, but its toughness was in no way inferior to JIS SKH ₉ . It can be seen that it can be used as a tool cutting edge without any problems. In other words, since "Invention Steel N" is manufactured using a powder metallurgy method, its workability does not significantly impair economic efficiency, and it has a uniformly distributed structure of fine grains of VC, NbC, or TiC carbide, amounting to several tens of volume percent. Therefore, it can exhibit remarkable wear resistance. When the vapor deposition coating of the present invention is applied to such material "Invention Steel N", the characteristics of vapor deposition tools for hard materials are (1) Longer life under normal conditions (2) High speed cutting (100 m/min or more) Expansion (3) When expanding into the area of cutting difficult-to-cut materials, it is possible to reduce the wear of the re-ground surface and to stop the rapid progress of wear after the vapor deposited layer is worn away. In addition, fine VC particles amounting to several tens of volume percent.
Because NbC or TiC carbide is uniformly dispersed in the matrix, the deposited layer is composed of a homogeneous material, so adhesion and crystal growth tend to be epitaxial, resulting in a film quality that is extremely advantageous for cutting performance. be. That is, FIGS. 4A and 4B show cutting speeds of a solid hob, a cutting tool according to an embodiment of the present invention, a hob made of other high-speed steel, and a solid hob made of other high-speed steel, respectively.
117m/min, feed 4mm/rev.No shift, work gear (SCM415.HB150~160.Module 3, pressure angle
20°) is a graph showing flank wear (Fig. 4A) and crater wear (Fig. 4B) corresponding to the cutting length of hob cutting performed under cutting conditions using climb cut and cutting oil. That is, this is an example of the cutting test results of hobs made of JIS SKH ₁₀ and "Invention Steel N" with and without TiC coating applied by the ion plating method under the same conditions. As a result, the effect of TiC coating on hob flank wear, the anti-crater effect of "invention steel N", and the combined effect of "invention steel N" + TiC coating (example) on flank wear were clearly recognized. It can be seen that the thickness of the vapor-deposited layer produced in the above-mentioned process greatly contributes to the improvement in machinability. Figures 5A and 5B show the cutting conditions of the solid hob according to the embodiment of the present invention and the conventional solid hob, cutting speed 120 m/min, feed rate 1.6 mm/min.
rev, shift 1.35mm, work gear (SCr415 (Hv160)
~200), module 3, pressure angle 20°) climb cut, flank wear (Fig. 5A) and crater wear (Fig. 5B) corresponding to the number of gear machining of hobbing cut under the conditions of using cutting oil. It is a graph showing each relationship. As a result, it is clear that JIS
Compared to SKH ₅₅ (melting method) + TiC coating, the present invention is superior in both flank wear and crater wear, and it can be seen that it greatly contributes to extending tool life. Figure 6 shows a solid hob with a cutting speed of 20m/
min, feed rate 0.5 mm/rev, no shift, work gear (S ₅₀ C HB ₄₇₅ module 3, pressure angle 20°), climb cut, and cutting of so-called difficult-to-cut materials using cutting oil conditions. Tools are JIS SKH ₅₅
It has been shown that there is less flank wear than that coated with TiC, and it can withstand more than twice the amount of cutting. Under these conditions, the amount of craters is small in both cases, but the flank faces are subjected to strong abrasion-pull wear and the coating layer is also worn away, but the wear resistance of the base material has a strong influence, and this difference in performance is seen. This is an example that led to this. In each of the Examples of the present invention, a standard hob having a module of 3 and a pressure angle of 20° was used as the "invention steel N", and was coated with a titanium compound. As a coating apparatus, the apparatus disclosed in Japanese Patent Publication No. 56-42672, shown in FIG. 7, was used. In other words, 1 is a decompression chamber,
2 is an electron gun, 3 is a titanium evaporation source, 4 is a coating material, that is, titanium, 5 is a support member for the object to be processed, 6 is a rotating shaft, 7 is a brush for current conduction, 8 is the object to be processed, that is, a solid hob, 9 is an ionizing electrode, 10
11 is an ionization power supply, 11 is an introduction pipe for the gas required to combine with the coating material titanium, 12 is an outlet of the gas introduction pipe, 13 is a gas control valve, 14 is a bias power supply for giving a negative potential to the solid hob, and 15 is a vacuum Shows the exhaust port leading to the pump. The coating conditions are as follows. Pressure in decompression chamber 1: 2×10 ^-3 Torr (0.266Pa) Electron gun 2: DC 800V, 1A, 270° magnetic field deflection Titanium evaporation source 3: Copper crucible with water cooling mechanism Titanium 4: 99.9% pure titanium Support member 5: Stainless steel (SUS304) jig with bolt tightening mechanism Rotating shaft 6: Stainless steel (SUS304) round bar with a diameter of 20 mm, rotation speed 30 revolutions per minute Brush 7: Stainless steel (SUS304) Ionization Electrode 9: Ring-shaped molybdenum wire (diameter 8 mm) electrode Ionization power source 10: DC 200V 50A Gas introduction pipe 11: Stainless steel (SUS304) pipe with outer diameter 10 mm and inner diameter 6 mm Gas outlet 12: Diameter 6 mm Gas control valve 13: Acetylene gas (for TiC coating in Figures 4, 5 and 6) or nitrogen gas (for TiN coating in Figure 6) is applied to reduce the pressure in vacuum chamber 1 to 2 x 10 ^-3 Torr.
(0.266Pa) Bias power supply 14: DC 1000V 1A Exhaust port 15: Directly connected to vacuum pump Coating time: 30 minutes in the case of Fig. 4, 40 minutes in the case of Fig. 5, 40 minutes in the case of Fig. 6 In addition, cut the left end cutting edge of the solid hob,
The rake face side was ground and the thickness of the coating layer was measured around the outer periphery of the incisor using a 1000x optical microscope. The results are shown in Table 1.

[Table] shows the minimum and maximum values.
Furthermore, regarding adhesion, we applied the Rockwell hardness C scale measurement method of JIS Z2245 Rockwell hardness test method from above the coating layer to judge the peeling of the coating layer caused by plastic deformation around the indentation. A test piece (10 x 10 x 20 mm) of the sample material shown in the table was quenched and tempered to H _R C66~67, ground, and mounted on a rotatable jig under the same conditions as in Figure 6. Table 3 shows the results of evaluating the adhesion using the method described above for those treated simultaneously. The results in this table also show that the invention material was coated with
The adhesion of the TiN layer was clearly improved compared to the comparative material, confirming that the cutting performance showed better flank wear.

【table】

[Table] As described above, the present invention makes it possible to significantly reduce the wear of conventional high-speed tool steel cutting tools. A cutting tool made of the highest quality high-speed tool steel, characterized in that it is coated with an effective compound among carbides, nitrides, and oxides by chemical vapor deposition or physical vapor deposition. It provides:

[Brief explanation of the drawing]

Figure 1 is a graph showing the high-temperature hardness of an example of tool steel used to form a cutting tool according to the present invention, ie, "Invention Steel N" and JIS SKH _9. Figure 2 is a graph showing the high temperature hardness of "Invention Steel N" and JIS SKH ₉ . Graph showing wear resistance by Okoshi type rapid wear test method, Figure 3 is a graph showing transverse rupture strength by bending test of "Invention Steel N" and SKH ₉ , Figures 4A and 4B
The figures show flank wear (Figure 4A) and crater wear (Figure 4B) corresponding to the cutting length in a hob that is a cutting tool according to an embodiment of the present invention and a hob made of other high-speed steel, respectively. 5A and 5B are graphs showing the respective relationships between the hob of the embodiment of the present invention and the conventional hob.
Flank wear corresponding to the number of hobbing gears cut using different cutting conditions from those shown in the figure (Figure 5A)
FIG. 5B is a graph showing the relationship between the temperature and crater wear (FIG. 5B). Furthermore, FIG. 6 is a graph showing the relationship between the cutting length and flank wear when cutting high-hardness work materials in a hob that is a cutting tool according to an embodiment of the present invention and a hob made of other high-speed steel. FIG. 7 is a schematic diagram showing an example of a coating device used for coating the steel of the present invention.

Claims (1)

[Claims] 1 In cutting tools, respectively in weight%,
C1.80~3.30%. Si0.10~0.60%. Mn0.10~0.60
%. Mo3.0~5.0%. W7.0~11.0%. Cr3.5~5.0
%. Co7.0-10.0%. N0.005-0.3% and V.
One type of Nb.Ti or the sum of two or more of these types is 8.0 to 11.0%, the balance is Fe and impurities, and it is formed by powder high speed steel manufactured by powder metallurgy method. Carbide of a metal of Group A, Group A or Group A of the periodic table on the surface of the cutting tool,
Deposit one layer of nitride, carbonitride, or alumina (Al ₂ O ₃ ), or two or more layers of arbitrary different types, and prevent crater wear on the rake face from which the coating layer has been removed after regrinding the cutting tool, or on the flank surface. A coated cutting tool characterized by reducing wear and eliminating chipping wear on ridge lines.