JPS63114804A - High-speed steel cutting tool - Google Patents

Abstract

PURPOSE:To aim at improvement in abrasion resistance of a cutting tool, by forming a quenching congealment layer rich in a celllike congealing structure in a cutting edge. CONSTITUTION:A quenching congealment layer 2 to be formed in a cutting edge predetermined part of high speed steel 1 by means of irradiation of a laser beam is roughly constituted of a dendrite structure part 3 being grown along a congealing progress direction and a celllike structure part 4 by homogeneous core formation. And, it is machined so as to cause this celllike congealing structure 4 to come to a cutting edge. Since a side of the celllike congealing structure part is more excellent in abrasion resistance than the dendrite congealing structure part, a suchlike cutting edge part is formed in the celllike structure part 4, whereby it can be made into such one that is very excellent in the abrasion resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high-speed steel cutting tool with excellent cutting performance, particularly wear resistance. In addition, the high-speed steel in the present invention includes not only the high-speed steel specified by JIS and the steel type generally called powder high-speed steel, but also the steel type that contains primary carbides and undergoes secondary hardening during tempering due to the precipitation of alloy carbides. This includes:

[Prior Art] Various improvements have been made to high-speed steel cutting tools in order to meet the recent demands for higher efficiency and higher precision in cutting. For example, according to Japanese Unexamined Patent Publication No. 59-83718, the surface of high-speed steel is irradiated with a laser beam to melt, rapidly solidify, and form a solid solution of primary carbides, and then tempered to significantly accelerate secondary hardening and increase hardness. Measures have also been proposed to improve toughness and, as a result, to improve wear resistance.

[Problems to be Solved by the Invention] However, the inventors of the present invention have conducted deeper research and consideration, and have found that the rapidly solidified layer formed by irradiation with a laser beam or the like always exhibits a single structure. Without,
We also found that the wear resistance of tools differs depending on the structure.

The present invention specifies the structure of the rapidly solidified layer formed by irradiation with a laser beam, etc., thereby providing a high-speed steel cutting tool with good wear resistance and excellent stability and reliability in terms of life and performance. This is what I am trying to do.

c. Means for Solving Problems] The present invention is a patent characterized in that the cutting edge portion has a rapidly solidified layer rich in cellular solidified structures.

[Function] As a result of research conducted by the present inventors, the rapidly solidified layer forming area obtained by laser beam irradiation etc. is as shown in the enlarged cross-sectional view shown in Fig. 1, and it is found that the rapid solidification layer formation area is formed at high speed! It was found that the rapidly solidified layer 2 formed at the expected cutting edge of No. 11 is roughly divided into a dendrite structure part 3 that grows along the direction of solidification progress and a cellular structure part 4 due to uniform nucleation. The first
The region 4' shown in the figure shows an intermediate structure between them, but in keeping with the gist of the present invention, it is appropriate to recognize that this region is also a cellular structure. Next, a cutting test was conducted using a high-speed steel cutting tool to investigate the relationship between the position of the cutting edge in the rapidly solidified layer and the amount of wear on the flank of the cutting edge, and the results shown in Figure 2 were obtained. 5 is rake face, 6 is flank face, ax
f indicates the grinding position.

According to the results, it can be seen that the wear resistance is particularly excellent when the grinding positions are d and e. In other words, the present inventors have come to the conclusion that the cellular solidified structure has better wear resistance than the dendrite solidified structure, and this is thought to be due to the uniformity of the cellular structure. . Therefore, if the cutting edge of the cutting tool is formed with the cellular structure 4, the wear resistance of the tool will be extremely high.
As a result, both the tool life and cutting performance are stable and reliable.

The conditions for conducting the cutting test were as follows.

(a) High speed steel bit: 5KH55 type (material) clearance angle
2゜ Rake angle 10゜ (B) Rapid solidification layer formation conditions: CO2 laser irradiation (wavelength: 10.6um) Output 5Kw Spot diameter: 1mm Machining speed: 5m/min (C) Tempering conditions: 550℃ x 3 times (d) Cutting conditions: Work material: 30M440 (Ho2O3) Cutting speed near m7 minute feed: 0.05 mm/rev Cutting length: 100 m (continuous cutting on the cylindrical end face) Next, the grain size of the cellular solidified structure and flank wear A cutting test using a high-speed steel tool was conducted to determine the amount.

The test conditions were the same as in the cutting test described above regarding the relationship between the cutting edge formation position in the rapidly solidified layer and the amount of wear on the cutting edge flank surface. However, the processing speed under laser irradiation conditions is 0.1 to 10 m/
The grinding process was performed so that the cutting edge forming position was the second jld position and the cellular solidified tissue part became the cutting edge. The test results are shown in Figure 3, and it is clear that the wear resistance of the cellular solidified structure depends on the cell diameter, especially when the cell diameter exceeds 8 μm. It can be seen that there is almost no difference from the amount). The reason for this seems to be that when the cell diameter exceeds 8 μm, the crystal grain size is almost the same as that of powdered high-speed steel, and the microstructure required to improve wear resistance cannot be obtained. .

In order to obtain a cutting tool having such a cellular solidified structure at the cutting edge, a rapidly solidified layer is formed in the area where the cutting edge is to be formed of high-speed steel, and then machining is performed so that the cellular solidified structure is located at the cutting edge. Alternatively, for example, by irradiating ultrasonic waves or the like during the solidification process to give vibration to the molten metal in the area where the cutting edge is to be formed, the proportion occupied by the cellular solidified structure within the rapidly solidified layer can be increased and the acceptable cutting edge forming position can be achieved. After the range has been expanded, machining as described above may be performed. Further, in order to improve wear resistance, it is preferable to perform tempering at a temperature of 500 to 600°C to cause a secondary hardening phenomenon and promote the formation of a rapidly solidified structure.

The means for forming the rapidly solidified layer is not limited to the present invention, but in consideration of ease of control and operation, it is preferable to use high energy density beam irradiation such as a laser beam, electron beam, or ion beam.

Furthermore, the high-speed steel cutting tools in the present invention include not only tools in which the entire tool is made of high-speed steel, but also tools in which only the cutting edge part involved in cutting is made of high-speed steel, such as reamers, broaches, shaving cutters, vinyl cutters, etc. On cutter, crack cutter, bevel cutter, end mill, hob,
Forming rack, cutting cutting tool (cold saw)
, phrasing cutters, milling cutters, drills, and tips and blades used in these tools.

[Example] Each example will be described below.
A rapidly solidified layer was formed by irradiation with an O2 laser (wavelength: 10.1 μm). In Examples 2 to 8, those in which a rapidly solidified layer containing a cellular solidified structure was formed only at the cutting edge involved in cutting were referred to as "products of the present invention." In addition, the comparative products used in each example were made according to conventional hardening and tempering conditions, but those with the annotation "(laser treatment)" were made from the same materials and under the same conditions as the inventive products. The cutting edge consists of a dendrite-like structure.

Example 1 Laser treated product 1 made of 5KH55 bit material and irradiated with laser
．． Laser-treated product subjected to ultrasonic vibration during laser irradiation 2. Comparative product without laser treatment 1. A comparison product 2 was prepared in which the material was Kl (A30) and no laser treatment was performed.

The laser processing conditions were as follows.

Output: 5Kw Spot diameter: 1mm Processing speed: 3m/min Further, the frequency of ultrasonic waves was set to jOMHz.

Using these cutting tools, the cutting length until the amount of flank wear reached 0.2 mm was measured.

Figure 4 is a perspective view of the cutting tool, and 5' is the rake face.

6' will rain on the flank.

Figures 5(A) and CB) are cross-sectional views taken along the line V-V in Figure 4. Figure 5(A) is for laser-treated product 1, and Figure 5(B) is for laser-treated product. This is case 2.

ao l al r a2 las I 84 +
as indicates the re-grinding position, in this case the number 1~
S indicates the number of times of re-grinding (see Figure 6).

The cutting conditions were as follows.

Work material: S0M440 (Ha 300) Speed =
7 m/minute feed: 0.05 mm/rev Cutting method: Two cylindrical end faces, continuous cutting, flank face. The test results are shown in Fig. 6, comparing the cutting length until the maximum wear amount reaches 0.2 mm.

In laser-treated product 1, a cellular structure appears at the cutting edge at the 3rd, 4th, and 5th grinding times [in the case of grinding positions as+a4+as in FIG. In the case of the re-grinding position "O+al*a3" in Fig. 5 (8), the wear resistance was higher than that of the cutting tool having the dendrite solidified structure part as the cutting edge.

In laser-treated product 2, the cellular coagulated tissue area was enlarged by laser irradiation while applying ultrasonic imaging.
Wear resistance is stable regardless of the position of the cutting edge [see Figure 5 (B)], and the re-grinding position a of laser-treated product 1
It was no different from the case of sh fi4+ as (see FIG. 5(A)).

As is clear from the above results, laser-treated product 2 and laser-treated product 1 at the 3rd, 4th, and 5th re-grinding times are the comparison product 1.
．． The result was that the lifespan was more than twice as long as that of 2.

When a rapidly solidified layer is formed by irradiation with a high energy density beam, melting occurs and the surface becomes uneven. The final product always requires finishing processing to the specified dimensions, but in order for the rapidly solidified layer to remain even after finishing processing from the beam irradiation surface side, it is necessary to take into account the amount removed in the depth direction during finishing processing.
．． It is considered necessary to form a rapidly solidified layer with a depth of 1 mm or more.

In addition, considering that defects may occur during beam irradiation or the surface portion may evaporate and a rapidly solidified layer may not be obtained, the cell diameter of the rapidly solidified layer should be kept to 8 μm or less. Then, the preferred conditions for beam irradiation are as follows, which are shown here for reference. However, in the following description, T is the time during which one point in the irradiation surface is irradiated (interaction time), and W is the irradiation energy density of the beam.

<CO2 laser irradiation conditions> The preferred range of T and W per shell is 5X10-' seconds≦T≦10-seconds...■2
x 103J/cm"≦W≦2
cm2"・■ outside the above range, evaporation occurs. The depth of the rapidly solidified layer is insufficient. Defects occur in the rapidly solidified layer. Problems such as insufficient cooling rate occur, and the cell diameter This results in a cellular structure of 8 μm or more, making it impossible to obtain the necessary characteristics.Here, T and W are the laser oscillation method,
The following conditions are given depending on the irradiation method.

(1) When one or several continuous wave beams parallel to the cutting edge are simultaneously scanned in parallel to form a rapidly solidified layer that partially overlaps.

Ttomi-Xo, 08 (seconds) ...■
■ W = -x 6 x 10'(J/am')
= ■ x V where S = Nispot (mm) V = Scanning speed (m/m1n) P = Laser output (Kw) (2) Scanning one or several pulse oscillation beams parallel to the cutting edge simultaneously in parallel to form a partially overlapping rapidly solidified layer.

As an additional condition, to obtain a continuous solidified layer is necessary [(1) is the case when d=100%].

Here, s, v, and p are the same as in (1).

d = Duty (%) f - Frequency (Hz) (3) When the beam is scanned in a direction parallel to the cutting edge while vibrating in a direction intersecting the cutting edge to form a rapidly solidified layer.

W = -x 6 x 10' (J/cm2)
...(if)XV *In each pulse oscillation, multiply by d.

Here, s, v, and p are the same as in (1). D is amplitude (am)
.

T' is the value of T obtained by ■ or ■. Roughly speaking, fθ is the vibration frequency (Hz), and in order to obtain a continuous solidified layer, ■
In addition to , [shares] (also ■ and ■ for pulse oscillation), the following conditions are required.

-x 18.7< S ・
...Of θ fθ>10 (Hz) ... @ electron beam irradiation conditions> Because the absorption rate of beam energy on the metal surface is different, the condition range regarding W changes (■ is the same, ■ is changed). The conditional expressions for determining W and T depending on the irradiation method are the same as in the case of laser irradiation.

Moreover, the reason for setting the upper and lower limit values is also the same.

5×10'''4 seconds≦T≦10-1 seconds...■
3 x 10 'J/cIIl''≦W≦3 x 10
'J/cm2...■゛Even if the laser is a YAG (yttrium, aluminum, garnet) laser, it is expected that the conditions for irradiation with the electron beam will be almost the same due to the absorption rate.

In this example, the frequency of vibration to be applied to the laser-treated product 2 was determined as follows. First, we determined the relationship between the frequency of ultrasound and the area ratio occupied by the dendrite solidified structure in the cross section of the rapidly solidified layer. The results are shown in FIG.

Under the laser irradiation conditions in this example, the cooling rate is estimated to be about 3X10'°C/sec judging from the secondary dendrite spacing, but by applying ultrasonic waves with a frequency more than 10 times that value, the cooling rate can be significantly reduced. An expansion of the cellular coagulation tissue area has been achieved. The cooling rate that can be achieved with a rapidly solidified layer with the minimum depth width required for a tool is 10'.
℃/sec, the frequency of the ultrasonic vibration to be applied is 1
By setting the frequency to about 0 MHz, a rapidly solidified layer consisting almost entirely of a cellular solidified structure can be obtained.

Example 2 Nindmill material comparison amount I 5KH56 2KHA30 3 5KH56 (laser treatment) Invention product 5KH56 Laser treatment condition Crab 5Kw Speed: 5 m/min Spot diameter: 1.5 mm Cutting conditions Number of teeth = 2 Diameter: 10 m + 1 mm Cutting material: S KD 11 (Ha-380) Feed rate: 80 mm/min Speed: 16 mm/min Depth of cut: 1 mm Test results The relationship between machining length and flank wear amount was investigated. The results are shown in FIG.

The life of the product of the present invention was improved by more than 3 times as compared to the comparative quantity 1.2, and 1.5 times as compared to the comparative quantity 3.

Example 3 Binion cutter material Comparison amount I KMC3 2KMC3 (laser treatment) Invention product KMC3 Laser treatment conditions output crab 5Kw Speed: 1 m/min Spot diameter: 15 mm Cutting conditions Rigidity material: SCM21 Cutting stroke number : (400v1500w)Str,
/min Dial feed: O, 12ma+/min Test results The relationship between the cutting length and the amount of wear on the trailing side was investigated. The results are shown in Figure 9.

The wear of the product of the present invention was extremely reduced compared to Comparison Quantity 1, and was about 273 compared to Comparison Quantity 2.

Example 4 Straight shank drill (10 mmφ) material comparison amount I 5KH51 23KH51 (TiN coating treatment) 3 3KH51 (laser treatment) Invention product 5KH5 Laser treatment conditions Output + 5Kw Speed: 5 m/min Spot diameter: 1. Omm Cutting conditions Work material S 50 C (l (a 250) hole diameter: 1
0mm feed: 0.18mm/rev speed
Degree: Comparison material 1, 2 18m/min laser treated material 2
5m/divided plate Thickness: 20t (through) Test results The number of holes was compared.

The results are shown in FIG.

The life of the product of the present invention was 103 times that of the comparative product and 1.5 times that of comparative product 3, approaching that of the coated drill (comparative amount 2).

Example 5 Groove milling material comparison amount I 5KH55 2KHA50 3KH'A30 (laser treatment) Invention product KHA 50 Laser treatment conditions Output crab 3Kw Speed: 5 m/min Spot diameter: 1.0 mm Cutting conditions Work material: S 40 C (Ha 150) Cutting speed:
17.6 m 7 min Feed rate: 90 mm/min Groove depth: 1.14 mm Test results Comparison was made based on the number of grooves cut. The results are shown in FIG.

The product of the present invention has a lifespan approximately 2.5 times that of the comparative product 1.2.

The amount was 1.2 times that of comparison amount 3.

Example 6 Hob specifications Material S KH55, module 2.5. Pressure angle 20° 1 thread number 3° groove number 12 Work gear specifications Spur gear, number of teeth 31. Helix angle 0°, SCM41 5H(l(B 150)82
．． 5×50w Cutting conditions Speed: 9am/min Feed: 4.0 mm/rev Talime cut without shift Laser IA burial condition Output: 5Kw Spot diameter: 1.5 IQIII speed = 3m/min Test result Flank surface maximum wear The cutting length until the amount reached 0.2 mm and the cutting length until the crater depth reached 0.02 mm were investigated. The results are shown in FIGS. 12(A) and (B).

In the product of the present invention, both vector wear and flank wear were reduced by 1.2 compared to the comparison amount, and the service life was improved.

Example 7 Bevel cutter material 5KH51 Work gear specifications Pitch circle diameter: 154.08 mm Number of teeth = 36 Helix angle: 351 Teeth 1fti: 23. Omm Tooth height: 10.5 mm Material: S0M415) 1a 150) Cutting conditions Speed: 43 m/minute feed Re: 0.12 mm/blade laser treatment conditions Test results The relationship between wear depth was investigated. The results are shown in FIG. We also investigated flank wear of the multi-blade at a cutting length of 90 m. The results are shown in FIG.

The product of the present invention had fewer craters and less flank wear than the comparative product 1.2, resulting in an improved life.

Example 8 Reamer material 5KH5 ruser processing conditions Output: 5Kw Spot diameter: 1. Omm speed = 3m/min Cutting conditions Work material: 540C (Ha 210) Speed: 10
．． 8m 7 minutes feed: 0.1 ~ 0.4
+nn+/rev Reamer allowance: 0.3 mm Processed hole diameter = 10 mφ Shown in relation to test results (R□8 and Ra).

It is thought that the product of the present invention has a cellular structure at the cutting edge, which makes the structure of the cutting edge finer and tougher, and improves adhesion resistance. Therefore, it seems that the finished surface roughness was improved as in this example.

[Effects of the Invention] Since the present invention is constructed as described above, the wear resistance of the cutting edge of the tool is excellent, and as a result, the life of the tool is improved and its stability and reliability are also high.

[Brief explanation of the drawing]

Figure 1 is an enlarged cross-sectional view of the rapidly solidified layer, the second side is a diagram showing the relationship between the grinding position of the rapidly solidified layer and the amount of flank wear, and Figure 3 is the relationship between the grain size of the cellular solidified structure and the amount of flank wear. Figure 4 showing
The figure is a perspective view of the cutting tool, Figures 5 (A) and CB) are v-v sectional views taken along the c'g line in Figure 4, Figure 6 is a diagram showing the relationship between the number of times the cutting edge is re-grinded and the cutting length, and Figure 7 The figure shows the relationship between the frequency and the area ratio occupied by the dendrite solidified structure when applying ultrasonic vibration to the rapidly solidified layer during laser irradiation, and Figure 8 shows the relationship between the machining length of the end mill and the amount of flank wear. The figure shown,
Fig. 9 is a diagram showing the relationship between the cutting length of a binion cutter and the amount of wear on the trailing side, Fig. 10 is a diagram showing the number of holes machined by a straight shank drill, and Fig. 11 is a diagram showing the number of grooves machined by a groove milling cutter. Figures 12 (A) and (B) are diagrams showing the cutting length of a regular blade hob, Figure 13 is a diagram showing the relationship between the cutting length and crater wear depth of a bevel cutter, and Figure 14 is a diagram showing the cutting length of the same cutting length of 90 m. Figure 15.18 is a diagram showing the flank wear for each month, and Figure 15.18 is a diagram showing the relationship between the number of reamers processed and the finished surface roughness. 2... Rapidly solidified layer 3... Dendrite structure part 4... Cellular structure part 5.5'... Cutting edge rake surface 6.6'... Cutting edge flank surface

Claims (1)

[Claims] A high-speed steel cutting tool characterized by having a rapidly solidified layer rich in cellular solidified structure at the cutting edge.