JP5509383B1 - Cutlery steel for ultrasonic vibration cutter and processing blade for ultrasonic vibration cutter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutlery steel for an ultrasonic vibration cutter which can be manufactured at a low cost and is durable and can be cut at a high speed.
[MEANS FOR SOLVING PROBLEMS] Among the carbides in the structure after quenching and tempering, the total area ratio of M ₆ C type and MC type carbides with an equivalent circle diameter exceeding 1 μm is 6 to 20%, and the average particle size is 1.2 to 7.0. Cutlery steel for ultrasonic vibration cutters that has a maximum particle diameter of 5 μm to 22 μm in terms of equivalent circle diameter.
[Selection figure] None

Description

  The present invention relates to a blade steel for an ultrasonic vibration cutter capable of cutting a fiber reinforced plastic such as CFRP at a high speed and a processing blade for an ultrasonic vibration cutter using the same.

  Fiber reinforced plastics such as CFRP are composed of high-strength fibers and resins, have very poor machinability, and have problems with tool life and processing speed.

  Conventionally, as a blade material suitable for cutting fiber-reinforced plastic, a clad material (see Patent Document 1) made of stainless steel for blades with an Fe-Al intermetallic compound sandwiched between them, and cutting of a prepreg with an ultrasonic vibration cutter A method (see Patent Document 2) has been proposed. Further, as an ultrasonic vibration cutter, a cutter having a processing blade in which hard particles such as a diamond tip are fixed to a blade tip portion (see Patent Document 3) has been proposed.

JP-A-9-29684 JP-A-3-228597 JP 2001-334494 A

  However, the cutting of the clad material with the blade has problems that the resistance to the blade works greatly, the processing speed is slow, the tool wear is remarkable, and the blade shape is limited to a thin plate. In addition, the cutting method using an ultrasonic vibration cutter is faster than the cutting with a general cutting tool, but when general carbon steel or stainless steel is used for the cutting blade, the cutting edge wears out early and cuts. Since it becomes impossible, the processing speed decreases, frequent replacement work is required, and the efficiency is poor.

  In addition, a tool in which hard particles such as a diamond tip are fixed to a cutting edge portion of a processing blade used for an ultrasonic vibration cutter has a problem that the tool life is long but the cost is high. The present invention has been made in view of such problems, and has low cost, durability, and cutlery steel for an ultrasonic vibration cutter capable of cutting at high speed, and ultrasonic vibration using the same. It aims at providing the processing blade for cutters.

  In order to achieve the above-mentioned object, the inventor uses the composition component of an ultrasonic vibration cutter blade steel suitable for cutting fiber-reinforced plastics and the rough particle size generated in the steel material, that is, the size of the primary carbide and the amount of the generated product. A certain area ratio was optimized. The thickness of the carbon fiber is about 5 to 18 μm, and cutting the fiber with a smooth cutting edge-shaped cutting blade has a high resistance when cutting the fiber (see FIG. 1). The inventor provides the blade edge with fine irregularities such as a saw blade having a size equal to or larger than the thickness of the carbon fiber, and thereby acts to cut the fibers in the irregularities by the movement of ultrasonic vibration (FIG. 2). As a result, it was found that cutting can be performed at a higher speed than a smooth cutting edge.

  For this, if there is a primary carbide having a size larger than the thickness of the carbon fiber in the steel blade, there is a moderate loss of primary carbide and residue by sharply polishing the cutting edge of the processing blade, It was found that fine irregularities were formed on the blade edge (see FIG. 3). Needless to say, the larger the amount of primary carbide is, the more the tool wear is suppressed. However, when a large amount of carbide of a certain size or more is generated, the cutting edge is severely damaged and cut instead. As a result, it was found that the tool life was reduced while the performance was impaired (see FIG. 4).

  Furthermore, when the quenching conditions and quenching and tempering hardness of the blade steel were examined, quenching was carried out immediately below the melting point (Ts), and the melting point was 30% higher than the maximum solid solution of carbon in the matrix structure. By quenching at a temperature lower than ° C. and tempering to a hardness of 63 HRC or higher, large chipping and wear of the cutting edge can be suppressed, and the tool life can be extended.

  The inventor has also found that the cutting speed of the ultrasonic vibration cutter is affected by the roughness of the cutting edge in addition to the material of the steel material. It has been found that the rougher the cutting edge, the lower the frictional heat generated at the time of cutting, and the lowering of softening and melting of the thermoplastic resin makes it possible to process at higher speed.

That is, according to the present invention, among the carbides in the structure after quenching and tempering, the total area ratio of M ₆ C type and MC type carbides having an equivalent circle diameter exceeding 1 μm is 6 to 20%, and the average particle size is 1.2%. The blade steel for ultrasonic vibration cutters is characterized in that it has a maximum particle diameter of 5 to 22 μm in terms of the equivalent circle diameter.

  In addition, the composition of the blade steel is, in mass%, C: 0.80 to 1.30%, Si: 0.01 to 0.70%, Mn: 0.10 to 0.40%, Cr: 3.50 to 5.00%, Mo: 5.00 to 7.50%, W: 5.00 to A composition containing 7.50%, V: 1.20 to 3.00%, and the balance consisting of Fe and inevitable impurities is desirable. A part of Fe is less than 10.00% of Co: and / or La, Ce, Hf, Y One or more may be substituted with 0.02 to 0.07%, and Ti + N may be limited to 0.2% or less.

  In addition, the hardness after quenching and tempering is 63HRC or more and the quenching temperature is 30 ° C or more lower than the melting point (Ts), so that more desirable characteristics can be obtained, and the processing for the ultrasonic vibration cutter by the steel of the present invention. The blade desirably has a polishing roughness of the blade edge of Ra: 0.10 μm to 1.50 μm.

The reason for each limitation will be described below.
C: 0.80 to 1.30%
C is an element important for securing strength, hardness, wear resistance, etc. necessary for blade steel by combining with carbide-forming elements to form carbides and forming a solid solution in the matrix. In order to obtain these effects, 0.80% or more is required. However, if the amount is too large, the cutting edge of the machining edge is lost due to coarsening of carbides, formation of excessive carbides, and deterioration of matrix toughness. %.
Si: 0.01-0.70%
Si is an element that acts as a deoxidizer and contributes to solid solution strengthening of the matrix. However, if too much is added, segregation is promoted, the distribution of carbides becomes uneven, wear resistance is impaired, and toughness is reduced.
Mn: 0.10 to 0.40%
Mn is also added as a deoxidizing and desulfurizing agent. However, if too much is added, MnS is formed together with S and is elongated in the forging direction to reduce toughness. Therefore, the content is made 0.10 to 0.40%.
Cr: 3.50 to 5.00%
Cr combines with C to form double carbides, increases quenching and tempering hardness, contributes to wear resistance, and improves hardenability. For this purpose, it is necessary to add at least 3.50% or more, but if it exceeds 5.0%, no significant effect is observed, so the upper limit is made 5.0%.
Mo: 5.00-7.50%
Mo combines with C to form M ₆ C, M ₂ C carbides. M ₆ C carbide that crystallizes during the solidification process contributes to wear resistance, and when it is present at the cutting edge of a processing blade, it drops off when the cutting edge is sharply polished, forming fine irregularities on the cutting edge. The present invention has a great feature that enables high-speed cutting of fiber-reinforced resin. Also, secondary carbides precipitated during heat treatment are important elements because they contribute to the strength of the matrix. To obtain these effects, at least 5.00% is required. However, if it exceeds 7.50%, coarsening of carbides and excessive carbide formation will be caused, so the upper limit is set to 7.50%.
W: 5.00-7.50%
W, like Mo, combines with C to form M ₆ C carbide, and is an important element for achieving the above characteristics. However, too much will produce coarse carbides,
5.00-7.50%.
V: 1.20 to 3.00%
V forms a very hard MC type carbide together with C. MC crystallized during solidification process
Type carbides, like carbides formed from Mo and W, contribute significantly to the above properties, and secondary carbides precipitated during heat treatment are important elements because they contribute to the strength of the matrix. In order to obtain these effects, it is necessary to contain at least 1.2%. However, if it exceeds 3.0%, MC type carbides become coarse and extremely hard, which impairs the workability of blade steel. Is set to 3.00%.
Co: 10.00% or less Co is an element that strengthens the matrix to increase the heat treatment hardness and imparts heat resistance, and reduces high-temperature softening of the matrix and associated wear. Since the ultrasonic vibration cutter generates frictional heat during cutting, the addition of Co is effective. However, adding a large amount reduces the toughness of the matrix and impairs hot workability, so the upper limit is 10.0.
0%.
One or more of La, Ce, Hf, and Y: 0.02 to 0.07%
La, Ce, Hf, and Y have the effect of lowering the crystallization temperature of the MC type carbide and making the particle size of the MC type carbide fine. MC carbide contributes to the wear resistance of the cutting edge, and if the particle size within a certain range is maintained, fine irregularities are formed on the cutting edge, contributing to higher cutting speed.
If it is too large, the workability of the blade steel will be hindered, so one or more of La, Ce, Hf, and Y may be added. For this purpose, it is necessary to add at least 0.02%, but if it exceeds 0.07%, no significant effect is observed, so the upper limit is made 0.07%.
Ti + N: 0.2% or less Ti and N serve as nuclei for the formation of MC type carbides, increase the crystallization temperature of MC type carbides, and increase MC
It greatly affects the grain size of type carbides. Less is preferable, but rare earth elements (La, Ce,
Depending on the balance with Hf, Y), 0.2% may be added to the upper limit for the purpose of controlling the MC type carbide to an appropriate size and amount.

  In order to cut the fiber reinforced plastic, an ultrasonic vibration cutter that cuts the fiber at high speed using ultrasonic vibration is suitable. However, the shape of the cutting edge of the processing blade is important for processing at higher speed. As described above, the thickness of the carbon fiber is approximately 5 to 18 μm, and the smooth cutting blade has a large resistance when cutting the fiber. By providing fine unevenness like a saw blade with a size, the action of cutting the fibers into the fine unevenness due to the movement of ultrasonic vibration works, and it can be cut at a higher speed than a smooth processing blade I found it. For this, if there is a primary carbide in the blade steel that is larger than the thickness of the carbon fiber, the cutting edge of the processing blade is thinly and sharply polished, so that there is an appropriate amount of missing and residual primary carbide. It was found that fine irregularities were formed.

Accordingly, it is desirable that the maximum particle size of the primary carbide existing at the cutting edge is 5 to 22 μm in terms of the equivalent circle diameter. In addition, the larger the amount of primary carbide is, the more the amount of primary carbide is present, the more the tool wear is suppressed, but when a large amount of carbide of a certain size or more is generated, the cutting edge is damaged and the cutting performance is deteriorated. It has been found to reduce lifespan. As a result of studying the balance between the size and the amount of primary carbide that achieves both tool life and high-speed cutting, the inventor found that the total area ratio of M ₆ C type and MC type carbides with an equivalent circle diameter exceeding 1 μm was 6 to 20 The average particle size was found to be in the range of 1.2 to 7.0 μm.

  Furthermore, when the quenching conditions and quenching and tempering hardness of the blade steel were examined, it was found that the quenching was carried out immediately below the melting point (Ts) and the carbon was dissolved in the matrix to the maximum solid solution. By quenching at a temperature lower than ° C. and tempering to a hardness of 63 HRC or higher, large chipping and wear of the cutting edge can be suppressed, and the tool life can be extended.

  Further, the inventor has a higher processing speed of the ultrasonic vibration cutter because the frictional heat generated at the time of cutting is lower when the cutting roughness of the blade is rough, and the softening and melting of the thermoplastic resin is suppressed. I found that it was possible. For this purpose, the polishing roughness of the blade edge is preferably set to Ra: 0.10 μm to 1.50 μm.

  The shape of the processing blade is not particularly limited, and as shown in FIG. 5, a thin blade attached to the tip of the horn of the ultrasonic vibration cutter (FIG. 5A is a double-edged type, and FIGS. 5B and 5C are single-edged types. As shown in FIG. 6, it is also applicable to a horn integrated type in which a horn and a thin blade are integrally formed of the same blade steel.

As described above, according to the present invention, the following various effects can be obtained.
(1) A fiber reinforced plastic such as CFRP can be cut at a high speed.
(2) A processing blade with excellent tool life can be manufactured at a low cost.
(3) Thick and complex-shaped machining blades can be formed as a single unit.

It is an image figure of carbon fiber cutting by a smooth blade. It is an image figure of carbon fiber cutting by a saw blade. It is a photograph of the cutting edge of a processing blade in which primary carbides have dropped off to form minute irregularities by sharpening. It is a photograph of the cutting edge of a processing blade that is largely damaged due to the presence of a large amount of coarse primary carbide. It is an example of the processing blade of an ultrasonic vibration cutter, (A) is a thin-blade double-blade type, (B), (C) is a thin-blade single-blade type. An example of a processing blade of an ultrasonic vibration cutter, which is a horn integrated type in which a horn and a thin blade are integrated.

    Examples of the present invention will be described below.

Table 1 shows chemical components of Examples 1 to 10 and Comparative Examples 11 to 15.
The sample was melted in a 2-3 ton induction furnace and a vacuum induction furnace and cast into a 600 kg mold.
The 600kg steel ingot is heated to 1,100 to 1,140 ° C and hot forged and annealed to a thickness of 65mm (860 ° C), and further heated to 1,140 to 1,170 ° C and hot rolled and annealed to a thickness of 4.5mm ( 860 ° C) was repeated, and then heated to 500 ° C and warm-rolled and annealed (860 ° C) to a thickness of 2 mm.

  This material is cut to a width of 17 mm, the quenching temperature is determined based on the melting (Ts) calculated from each component, and after quenching in a vacuum quenching furnace, it is 2 to 540 to 600 ° C. Three tempers were performed. Table 2 shows the melting point (Ts), quenching temperature, and hardness after quenching and tempering of each sample. The melting point (Ts) was obtained from the calculation formula Ts (° C) = 5/9 * (2310-200 (C%) + 40 (V%) + 8 (W%) + 5 (Mo%) -32). .

Table 3 shows the results of image analysis of the carbides of each of the samples tempered and tempered, and the area ratio and particle size of M ₆ C type and MC type carbides were measured.

  For image analysis, the vertical cross-section (cross-section parallel to the forging and rolling direction) of the specimen was examined by 10% oxalic acid electrolytic corrosion and Murakami reagent corrosion, and the equivalent circle diameter and area ratio of carbides exceeding 1 μm. Asked. The equivalent circle diameter referred to here is a particle diameter, and indicates the diameter of a circle when the area of each carbide in the cross section is measured and replaced with a perfect circle. Further, the area ratio is the amount of carbide generated, and refers to the ratio of the area of carbide occupying the speculum area.

  On the other hand, a thin blade of the double-edged type shown in FIG. 5 (A) having a width of 15 mm, a thickness of 1 mm and a length of 35 mm was produced from each of the samples quenched and tempered. The cutting edge was sharply polished to the thickness of 10 μm or less at the thinnest point.

Here, Examples 7 to 10 and Comparative Examples 14 and 15 are the same steel material, and only the polishing roughness of the blade edge of the thin blade is changed. Table 4 shows the roughness of the cutting edge of the sample. The thin blade was attached to an ultrasonic vibration cutter, and a CFRP sheet material cutting test was performed.
The conditions for the cutting test are as follows.
Frequency: 40kHz
Ultrasonic output: 400W
Work material: 0.8mm thick CFRP sheet material
(Base material: Polypropylene, containing 30% carbon fiber with a thickness of 7μm)

(Cutting test 1)
In order to confirm the effect of extending the life of the cutting blade, the cutting speed was fixed at 100 mm / sec. The workpiece material was cut until the cutting blade reached the end of its life, and the cutting distances were compared. The processing speed here refers to the feed speed of the processing blade. The life of the cutting blade was judged as the life when delamination was observed on the cut surface of the workpiece. Table 4 shows the cutting distance at this time and the state of damage to the cutting edge when the life is reached. From this result, it was found that the machining blade according to the present invention has high durability.

(Cutting test 2)
Next, in order to confirm how far the machining speed could be increased with each machining edge, the machining speed was gradually increased by 20 mm / sec for every 10 m of workpiece material, and the machining limit was confirmed. Table 4 shows the processing limits at this time. Here, the machining limit was determined as the point at which delamination was observed in the workpiece material. From this result, it was found that the processing blade according to the present invention can be processed with high efficiency, and that the processing speed can be further increased by setting the processing roughness Ra of the cutting edge to 0.10 μm to 1.50 μm.

Claims (5)

By mass% C: 0.80 to 1.30%, Si: 0.01 to 0.70%, Mn: 0.10 to 0.40%, Cr: 3.50 to 5.00%, Mo: 5.00 to 7.50%, W: 5.00 to 7.50%, V: 1.20 to 3.00 %, The balance consisting of Fe and inevitable impurities,
Among the carbides in the structure after quenching and tempering, the total area ratio of M ₆ C type and MC type carbides with an equivalent circle diameter exceeding 1 μm is 6-20%, and the average particle size is 1.2-7.0 μm, Furthermore, a cutter steel for an ultrasonic vibration cutter, wherein the maximum particle size of these carbides is a circle equivalent diameter of 5 μm to 22 μm.   The blade steel for an ultrasonic vibration cutter according to claim 1, wherein a part of Fe is replaced with Co: 10.00% or less.   3. A part of Fe is replaced with one or more of La, Ce, Hf, and Y by 0.02 to 0.07%, and / or Ti + N is 0.2% or less. The blade steel for ultrasonic vibration cutters as described. 4. The blade for an ultrasonic vibration cutter according to claim 1, wherein the hardness after quenching and tempering is 63 HRC or more and the quenching temperature is 30 ° C. lower than the melting point (Ts). 5. steel.
Ts (℃) = 5/9 * (2310-200 (C%) + 40 (V%) + 8 (W%) + 5 (Mo%)-32)   5. The processing blade for an ultrasonic vibration cutter using the cutter steel according to claim 1, wherein the polishing roughness of the blade edge is Ra: 0.10 μm to 1.50 μm.