JPS60177167A - High-speed steel drill - Google Patents

Abstract

PURPOSE:To provide a high-speed steel drill having a hardened surface by subjecting the specifically composed high-speed steel drill to a heat treatment for hardening and tempering after mild carburization under specific conditions, and subjecting the drill to outside diameter grinding and slotting then to a gas soft nitriding or liquid soft nitriding treatment followed by a homogenizing treatment. CONSTITUTION:A high-speed steel drill is composed, by weight %, of 0.7-0.9 C, 0.1-0.5 Si, 0.1-0.6 Mn, 3.5-5 Cr, 4-6 Mo, 4.5-7 W, 1.5-2.5 V and the balance Fe with inevitable impurities. The drill is carburized to 0.95-1.2% surface C and 0.3-0.8mm. carburization depth at the temp. below the transformation point of the high-speed steel and is then subjected to a heat treatment for hardening and tempering. The treated drill is subjected to outside diameter grinding and slotting then to a gas soft nitriding or liquid soft nitriding treatment at about 560 deg.C followed by a homogenizing treatment to have about 1,000Hv surface hardness.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a manufactured drill. That is, in weight percent, C0
．． 70 ~ 0.9 (1, St O.10-0.50%,
Mno. 10-0, 60%, Cr3.5-5.0%,
Mo4. 0 to 6. 0%, W4.5~7.0%,
Vl. A high-speed steel drill consisting of 5 to 2.5%, the balance iron and some impurities, with a surface hardness of around Hv920.
After bottom hardening by relaxation carburizing to a hardening depth of 0.4 to 0.8 m, the hardening process was continued at 560°C.
It is characterized by gas soft nitriding or liquid soft nitriding treatment at the front and rear, and homogeneous treatment to achieve a surface hardness of around Hv1000, and it has extremely excellent cutting performance.

As a surface hardening method for high-speed steel drills, a nitriding method has conventionally been generally used. High speed steel is WlCr, Mo,
Since it contains a large amount of alloying elements such as V, it has rapid nitriding properties, and even when the nitriding time is relatively short, a very high surface hardness can be obtained. In this case, when the surface hardness becomes as high as HvllOO~1200, the nitrided layer becomes brittle and the cutting performance of the drill is significantly reduced. Therefore, when applied to a drill, the surface hardness of the nitrided layer is Hv 100
It must be adjusted to around 0-1050.

In order to create a nitrided layer with a Hv of around 1050 on a high-speed steel drill, it is sufficient to shorten the nitriding treatment time, but because of the short treatment time, the nitriding depth also becomes shallow, ranging from o, oio to 0.015 inertia. The internal hardness of the high-speed copper drill is Hv 84
Since the hardness gradient of the surface hardened layer of such short-time processing drills is around 0, the hardness gradient of the surface hardened layer of such a short-time processing drill is too steep, resulting in a disadvantage that the hardened layer lacks strength and is likely to shorten its life due to cutting edge chipping.

Therefore, in order to improve the cutting performance of a drill by surface hardening due to nitriding, it is necessary to make the hardness gradient of the nitrided layer gentler so that the edge strength is +/-. As a result of extensive research, the present inventor first applied relaxation carburization to the surface of a high-speed steel drill to form a hardened layer with a surface hardness of around Hv920 and a hardening depth of 0.4 to 0.81+lI++. , Furthermore, the surface hardness t-
By setting the Hv to around 1050, and then making the surface hardness "tHv around 1000 through homo-treatment, it was possible to obtain a high-speed steel drill with extremely excellent cutting performance. The manufacturing process is slightly different depending on whether the groove is formed by grinding or the case where the groove is formed by cutting and then heat-treated. At a temperature below 750℃, for example, the surface C is 0.95 to 1.2 degrees, and the carburization depth is 0.3 to 0.
．． After mild carburizing to 8+mn, heat treatment of quenching and tempering, outer diameter grinding and groove grinding, followed by gas soft nitriding or liquid nitriding treatment at around 560℃, and then Homo treatment is performed to finally achieve a surface hardness of around Hv1000 and a hardening depth of 0.2 to 0.6wn. In addition, when grooving is performed by cutting, after grooving a high-speed steel rod by cutting, mild carburizing is performed, quenching,
It is manufactured by performing tempering heat treatment, finish grinding, followed by gas soft nitriding or liquid soft nitriding treatment at around 560°C, and finally homo treatment.

Next, the reasons for limiting the composition of the drill of the present invention will be described.

C increases the hardness of martensite and crsW%Mos
It combines with V to form a hard carbide and improves wear resistance, but if C is less than 0.70%, hardness is insufficient, and if C is 0.
．． If it exceeds 90%, the toughness decreases, so the sail is 70~0.9
It was set to 0%. St is added as a deoxidizing agent, but if it is less than 0.1%, its effect is small, and if it exceeds 0.5%, decarburization becomes easy, so it is set at 0.10 to 0.50%. Mn also has a deoxidizing effect, but if it is less than 0.1%, the effect is small.
Moreover, if it exceeds 0.60%, residual austenite increases during quenching, so it is set at 0.1 to 0.6%. Cr increases hardenability, but if it is less than 3.5%, the effect is small, and if it exceeds 5%, toughness decreases, so 3.5 to 5.0%.
And so. Mo greatly increases hardenability, increases temper softening resistance, and greatly increases wear resistance, but if it is less than 4.0%, the effect is small, and even if it exceeds 6%, the improvement in the effect is small. .0 to 6.0%. W also forms carbides and improves wear resistance, but if it is less than 4.5%, the wear resistance is insufficient, and if it exceeds 7,0-, the toughness decreases.

The content was set at 4.5 to 7.0%. (2) also forms special carbides and improves wear resistance, but if it is less than 1.5%, the effect is small, and if it exceeds 2.5%, the toughness decreases, so 1.5%
It was limited to ~2.5 inches.

Hereinafter, the effects of the present invention will be explained using examples.

Table 1 shows the chemical composition of the steel that makes up the drill sample.

Table 1 Chemical composition of sample material (%) Table 2 shows the cutting test results of a 10.0φ5KH9 drill manufactured by grinding and grooving after heat treatment. In the table, symbol A is a 5KH9 homo-treated drill, quenched at 1220℃, tempered twice at 560℃,
Homo treatment was performed at 550°C. The symbol B is
A 5KH9 high-speed steel rod was heated at 750°C for 6 hours in a carburizing atmosphere gas with carbon and a potential of around 0.4 inches.
After heating and mild carburizing, 1200℃ quenching, 5
This drill was tempered twice at 60°C and then homo-treated at 550°C. Symbols C and 2 are drills of the present invention. In other words, symbol C is carburized under the same conditions as symbol B, then quenched at 1200°C, tempered twice at 560°C, subjected to soft nitriding at 560°C x 151 ru gas in a Unisif furnace, and finally homogenized at 550°C. It has been processed. The symbol is a material with the symbol CO gas nitrocarburizing, which is subjected to liquid nitrocarburizing at 570° C. x 5 ml, that is, tuftride treatment. Symbol E is a drill 'e made of 5KH9 which was quenched at 1220°C, tempered twice at 560°C, subjected to liquid nitrocarburizing or tuftride treatment at 570°C x 5xia, and then subjected to homo treatment at 550°C.

The cutting conditions are rotation speed 78 Or'p'ms and cutting speed 2.
4.5 m/vaia, speed 90.3 trrrty'r
ev % Hole depth was 40 μm blind hole, and Johnson Wax JR570 water-soluble cutting oil was used. Work material is SK
D 61 and HB 277 tempered materials were used. The homo-treated drill with symbol A had 35 holes drilled, while the relaxed carburized homo-treated drill with symbol B had 53 holes drilled, indicating improved cutting performance due to relaxed carburization. In addition, the liquid nitrocarburized and homotreated drill with symbol E showed cutting performance with a number of holes drilled of 79, but the drills of the present invention with symbols C and D showed the number of holes drilled with 96 and 98 tons, respectively. It showed outstanding cutting performance.

Next, Table 3 shows the results of a cutting test for a drill made of 11.5φ5KH9, which was manufactured by cutting a groove and then heat-treating the drill. The cutting conditions are: rotational speed 780 ipm s cutting speed 28.2r
rL〆11 send? ) Ol 3 ran/rev % Hole depth is 40mm blind hole, Johnson, Wax JR570
A water-soluble cutting oil was used. Work material is SKD 61, H
B293 tempered material was used.

Symbol H is a carbon,
7 in a carburizing atmosphere gas with a potential of around 0.4%.
After mild carburizing by heating at 50°C for 6 hours,
It was quenched at 0°C, tempered twice at 560°C, and then finished ground, followed by soft nitriding at 560°C x 15 wax gas, and finally homo-treated at 550°C. Further, the symbol design is also the drill of the present invention, which is obtained by adding gas nitrocarburizing with the symbol H to liquid nitrocarburizing, that is, tuftride treatment at 570° C. and 85 ml. The symbol F is a homo-treated drill, and the symbol G is a mild carburizing, homo-treated drill. Further, the symbol J is a liquid soft nitriding, homo treatment drill.

The homo-treated drill with symbol F made 20 holes, while the relaxed carburized and homo-treated drill with symbol G made 38 holes, indicating improved cutting performance due to relaxed carburization. Also, the symbol J
The liquid nitrocarburized, homo-treated drill shown in Fig. 1 shows cutting performance with 93 holes drilled, while the drills of the present invention with symbols H and I have a cutting performance of 116 and 115 holes, respectively. Yoshi also showed outstanding cutting performance.

As explained above, when a drill is manufactured using a manufacturing process in which grooving is performed by grinding after 1 heat treatment, and when a drill is manufactured through a manufacturing process in which grooving is performed by cutting 1 and then heat treatment is applied. Even in the case of C0, 70-0.90%, St O, 10-0.5
0%, Mn 0.10~O-60%, Cr3.5~5.
0%, M, 4.0-6.0%, W4.5-7.0%, 7
First, the surface of a high-speed steel drill with a chemical composition of 1.5 to 2.5% is heated to a temperature below the transformation point of the high-speed steel, e.g.
At 50℃, surface C is 0.95 to 1.2 inches and carburization depth is 0.
．． 3 to 0.8 ttm to form a hardened layer with a surface hardness of around HV920], followed by gas soft nitriding or liquid soft nitriding to increase the surface hardness to around HV1050, Finally, by performing a homo treatment to obtain a surface hardness of around 100Q, it was possible to obtain a high-speed steel drill with significantly superior cutting performance compared to mild carburizing drills and nitriding drills.

Agent Tsuneteru Aragaki

Claims (1)

[Claims] f in weight%, C0.70 to 0.90 inches, 830.10
~0.50%, Mn O-10~O-60%, Cr3.
5-5.0%, Mo 4-0-6-0%, W4.5
~7.0%, ■1.5~2.5%, balance iron and some impurities, a rod of high speed steel with a surface C of 0.95~1 at a temperature below the transformation point of the high speed steel. .2chi,
After mild carburizing to a carburizing depth of 0.3 to 0.8 mK, heat treatment of quenching and tempering is performed.
External diameter grinding and groove grinding are performed, followed by 560℃
After performing gas soft nitriding or liquid soft nitriding treatment on the front and back, a complete homo treatment was performed to achieve a surface hardness of t Hv 10.
A high-speed steel drill characterized by having a diameter of around 00. 2 Weight -, C0.70-0.90 cm, SiO,10
~o, sos, Mn0.10-0.60%, Cr3-5
~5.0%, Mo 4-0~6*0%, W4.5~
7.0%, Vl, 5 to 2.5%, balance iron and some impurities.After cutting or grinding a rod of high speed steel to create grooves, Relaxation carburization is carried out at a temperature such that the surface C becomes 0.95 to 1.2 inches and the carburization depth becomes 0.3 to 0.8 m.
After heat treatment of quenching and tempering of /11, finish grinding, followed by gas soft nitriding or liquid soft nitriding at around 560℃, and then homo treatment to increase the surface hardness to Hv1000. A high-speed copper drill that features a front and back drill.