KR20100121058A - Tool holder using carbon nano tube composition material and fabricating method its - Google Patents

Abstract

PURPOSE: A tool holder using carbon nano tube composition material, for preventing machining and chattering by increasing natural frequency and damping ratio, and a manufacturing method thereof are provided to secure the optimum performance by increasing rigidity and hardness using titanium nano heat treatment. CONSTITUTION: A tool holder using carbon nano tube composition material comprises a tool head part(110), a core shaft(120), a composition material part(130), an hollow cylindrical metal cover(140). One or more cutting tool is installed in the tool head part. One end of the tool head part is assembled in the core shaft. The core shaft is inserted into a central hole of the composition material part. The composition material part is made of carbon fiber epoxy and the mixed composite material of the carbon nano tube.

Description

Tool holder using Carbon Nano Tube Composition Material and Fabricating Method its}

The present invention relates to a tool holder using a carbon nanotube composite material and a method for manufacturing the same, and more particularly, by combining nanotechnology to reduce the overall weight to reduce the processing load, to increase the natural frequency and damping ratio to chattering during machining The present invention relates to a tool holder using carbon nanotubes having an optimum performance by increasing surface hardness and increasing rigidity by titanium nano heat treatment, and a method of manufacturing the same.

In general, the most difficult process in cutting machining has been developed by a variety of methods, such as boring or reaming hole, and especially among the tool makers KENNAMETAL in the United States, SANDVIK COROMANT in Sweden, TEENESE in Norway, etc. We developed a built-in boring holder and a milling holder, and developed a dimple bar with a cross-sectional shape designed to distribute the cutting force for the main component and the distribution force by giving grooves to the boring heads of SUMITOMO and MITSUBISHI MATERIAL in Japan. Mapal has developed padded reamers and boring bars for deep hole machining.

The holder with the built-in copper reducer increases the overall weight and additionally needs a space for entering the copper reducer, so that chattering does not occur due to vibration attenuation during processing, while the cross section of the head is weakly designed and sagging due to cutting force It becomes large, and the deflection varies greatly depending on the cutting thickness. This mechanism acted as a major cause of lowering the precision of dimensional tolerances in machining.

In addition, dimple bar is made of alloy steel and tungsten carbide body, and is mainly used for small turning work.In case of reamer with pad, guide pad catches the machined hole to catch disturbance of cutting tool holder by chattering. will be.

However, if the pad does not bend smoothly so as to touch the processing surface, it will vibrate in a fine gap.

In addition, in the case of Mapal, tools such as NC reamers, which are available as standard reamers, are designed so that the diameter of the stem between the head and shank is as small as 50-60% of the head. In addition, since the stiffness to hold against the cutting force is reduced so that the pad completely slides on the machining surface of the hole and the stiffness is small, the machining is performed below the resonance region that may be generated during the machining. However, as the depth of the hole increases, the straightness of the processing hole changes along the base hole.

In particular, in the case of machining that requires the straightness of the hole to be precisely processed, such as camshaft journal processing of a car engine head of a long distance, NC reamers are used, and products with long pads are used. The diameter must be increased to increase rigidity and to support deformation with guide pads.

However, these products are quite expensive, and the longer the product, the worse the surface roughness as the aging deformation becomes a problem and the shorter the tool life.

In addition, according to Korean Patent Registration No. 0683943, a tool holder using an internal pitch-based high rigid carbon fiber epoxy composite material is disclosed. Such a tool holder can reduce the overall weight and increase rigidity to give a natural frequency in a high range, and can suppress vibration with high attenuation.

However, such a conventional tool holder has a lower rigidity than the carbon fiber epoxy composite material exposed to the outside because the outer part, which is a metal cover surrounding the outside with the carbon fiber epoxy composite material as the inner part, is made of a general alloy steel material. Accordingly, the rigidity of the metal cover for protecting the outside is insufficient, and the rigidity of the metal cover as the outer protective cover is also ignored in the structure. In addition, in the tool for processing aluminum alloy having a high Si content, erosion of the tool holder due to the chip occurs at the portion where the chip is generated. The hardness of the alloy steel has a problem that such erosion can not be prevented.

Therefore, the present invention is to solve the above problems, the purpose is to reduce the overall weight by combining nanotechnology to reduce the processing load, to increase the natural frequency and damping ratio to prevent chattering during machining, by heat treatment It is intended to provide a tool holder using a carbon nanotube composite material having an optimum performance by increasing the surface hardness and increasing rigidity, and a method of manufacturing the same.

As a specific means for achieving the above object, the present invention is a tool head which is provided with a replaceable at least one cutting tool for processing the inner peripheral surface of the hole formed in the object; A core shaft of a predetermined length having one end assembled to the tool head; A composite material portion formed of a composite material in which the core shaft penetrates and is formed in close contact with one end of the tool head, and the carbon fiber epoxy and carbon nanotubes are mixed with each other; And it provides a tool holder using a carbon nanotube composite material including a hollow cylindrical metal cover inserted into the composite material portion to cover the entire outer surface or a portion of the outer surface of the composite material portion.

Preferably, the composite material portion is made of a hollow cylinder-shaped molding using a mixture of 4 to 6 wt% carbon nanotubes mixed in carbon fiber epoxy.

Preferably, any one of the tool head portion, the core shaft and the metal cover is heat-treated titanium nano.

Preferably, the tool head portion comprises at least one guide pad made of one of polycrystalline sintered diamond, cemented carbide, or cermet material to contact the inner circumferential surface of the hole to be machined.

Preferably, it further comprises an end portion which is screwed with the other end of the core shaft is inserted into one end of the metal cover to be fixed in close contact with one end of the composite material.

In addition, the present invention is a tool head portion that is replaceably provided with at least one cutting tool for processing the inner peripheral surface of the hole formed in the object, the core shaft one end is assembled to the tool head portion, and the core shaft is inserted In the method of manufacturing a tool holder comprising a composite material portion formed in close contact with one end of the tool head portion formed through the central hole is disposed and a metal cover inserted into the outer surface of the composite material portion, the composite material portion is carbon It is made of a hollow cylinder-shaped molding is formed of a mixture of 4 to 6wt% carbon nanotubes in the fiber epoxy, wherein any one of the tool head, the core shaft and the metal cover is heat-treated titanium nano before assembly Provided is a tool holder manufacturing method using a carbon nanotube composite material.

According to the present invention, the composite material portion to be combined with the tool head portion is provided with a composite material in which carbon nanotubes are mixed with a certain amount of carbon nanotubes, and inserted into the composite material portion so as to cover the entire outer surface or a part of the outer surface of the composite material portion. Titanium Cover

By reducing the overall weight of the tool holder by reducing the overall weight of the tool holder, it reduces the load during machining, prevents chattering during high-speed machining by increasing the natural frequency and damping ratio, and obtains precise dimensional tolerances, surface roughness and shape tolerances. By the heat treatment, the surface hardness of the metal is increased, the rigidity and the elastic modulus are increased, so that the service life of the tool holder can be significantly extended as compared with the conventional one, and the maintenance period is also long.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is an assembly view showing a tool holder using a carbon nanotube composite material according to a first embodiment of the present invention, Figure 2 is a tool holder using a carbon nanotube composite material according to a first embodiment of the present invention It is an exploded perspective view shown.

As shown in FIGS. 1 and 2, the tool holder 100 according to the first embodiment of the present invention includes a tool head part 110, a core shaft 120, a composite material part 130, and a metal cover 140. ) And end portion 150.

The tool head unit 110 is provided with at least one cutting tool 112 is replaceable so as to boring or reaming the inner circumferential surface of the hole formed in the object to be processed, such as cast or molded.

Accordingly, the tool head 110 is provided with a clamp 113 to securely fix the cutting edge, which is a cutting tool arranged in the insert type.

In addition, the tool head portion 110 adjacent to the cutting tool 112 is formed of one of polycrystalline sintered diamond, cemented carbide, or cermet material to prevent disturbance generated during the hole cutting process. At least one guide pad 114 in contact with the inner circumferential surface is provided.

In addition, the tool head portion 110 adjacent to the cutting tool 112 and the guide pad 114 has an inner hole of the core shaft 120 toward the cutting tool 112 and the guide pad 114 during cutting. It is provided with a cutting oil discharge hole 116 for spraying the cutting oil supplied through 121 at a constant strength.

Accordingly, lubrication and cooling are performed while the frictional resistance between the cutting tool 112 and the processing part is minimized by the cutting oil supplied during cutting, and lubrication between the guide pad 114 and the inner circumferential surface of the hole in contact with the cutting tool 112 is performed. The frictional resistance can be reduced, and the other of these guide pads can also be in setting the dimensions of the cutting edge.

One end of the core shaft 120 is assembled to the tool head part 110, and is made of a hollow pipe metal material having a predetermined length of the inner hole 121, and is formed at both ends of the core shaft 120. One end of the formed male screw portions 122 and 124 is screwed to a female screw portion (not shown) formed at one end surface of the tool head portion 110 so that the core shaft 120 and the tool head portion 110 are integrated.

The composite material portion 130 is a hollow cylindrical body formed by penetrating the center hole 132, the core shaft 120 is inserted into the center of the body, the composite material portion 130 of the core shaft 120 One end of the coupling portion 116 recessed to one end surface of the tool head 110 to which the male screw portion 122 is assembled is inserted and assembled.

The composite material unit 130 is preferably made of a molded article molded into a mixture of carbon nanotubes carbon nanotubes 4.0 to 6.0wt% mixed in a hollow cylinder.

Accordingly, the carbon nanotubes have a relatively high modulus of elasticity and high tensile strength compared to carbon fiber epoxy to compensate for the low stiffness and strength of epoxy.

 The metal cover 140 is provided in the hollow tube-shaped metal inserted into the composite material portion 130 is provided approximately the same as the overall length of the composite material portion 130 so as to cover the entire outer surface of the composite material portion 130 It consists of members.

Here, when the metal cover 140 is provided with a length enough to cover the entire outer surface of the composite material portion 130, the metal cover 140 of a predetermined length adjacent to the tool head portion 110. It consists of a small diameter portion 141 and a large diameter portion 142 having a larger outer diameter size than the outer diameter of the small diameter portion 142 is bitten fixed to the tool chuck.

The metal cover 140 is heat-treated titanium nano before being combined with the composite material 130, the metal cover made of high elastic, high-strength alloy steel surface strength and rigidity is increased, there is no distortion or dimensional change, the elastic modulus is increased Excellent heat resistance and corrosion resistance, and excellent surface hardness can be obtained.

In addition, it is preferable that the tool head portion 110 and the core shaft 120 made of a metal material together with the metal cover 140 are also heat treated with titanium nano before assembly of the holder so as to increase surface strength and rigidity.

The end portion 150 is provided with a female screw portion 154 screwed to the male screw portion 124 formed at the other end of the core shaft 120 at the center of the body and screwed with the other end of the core shaft 120. While being in close contact with one end of the composite material 130.

The end portion 150 is preferably in close contact with the end surface of the composite material portion 130 is inserted into the inside of the metal cover 140 together with the composite material portion.

3 is an assembly view showing a tool holder using a carbon nanotube composite material according to a second embodiment of the present invention, Figure 4 is a tool holder using a carbon nanotube composite material according to a second embodiment of the present invention As shown in the exploded perspective view, the tool holder 100a includes a tool head part 110, a core shaft 120, a composite material part 130, and a metal cover 140a, similarly to the tool holder of the first embodiment.

The metal cover (140a) is provided with a relatively short length than the length of the composite material portion 130 to cover a portion of the outer surface of the body of the composite material portion 130 and to expose the remaining outer surface of the body to the composite It is inserted into the material portion 130.

Table 1 shows the strength, elasticity and density change of the composite portion according to the change in the content of carbon nanotubes.

Here, the carbon fiber epoxy used a pitch-based high-stiffness carbon nanofiber epoxy composite material.

 Carbon nanotubes 1wt% 2wt% 3wt% 4wt% 5wt% 6wt% 7wt% 8wt% 9wt% 10wt% Composite material department

burglar
(MPa) 1500 1600 1700 1770 1800 1780 1650 1500 1400 1200 Shout
(GPa) 385 400 410 480 500 485 410 390 350 340 density
(Kg / m ³ ) 1700 1685 1670 1655 1650 1630 1615 1600 1585 1570

As shown in Table 1, since the carbon nanotube content is 4.0wt% or less and 6.0wt% or more, it can be seen that mechanical properties such as strength and elasticity of the composite portion are degraded and density is increased, thereby forming the carbon of the composite portion. The content of the nanotubes was 4.0 to 6.0wt% was the most appropriate, 5.0wt% was found to be the best.

The density of the composite material was found to decrease as the content of carbon nanotubes increased.

Table 2 shows the mechanical properties of the prior art made of a carbon fiber epoxy composite material, including carbon nanotubes in the epoxy.

Conventional Invention Longitudinal Young's Modulus (Gpa) 382 500 Longitudinal strength (MPa) 1500 1500 Lateral Young's Modulus (GPa) 5.1 15 Lateral Strength (MPa) 24 98 Poisson's ratio (γ) 0.29 0.29 Density ρ (Kg / m ³ ) 1755 1650 Damping Ratio (ζ) 0.0207 0.0420

As shown in Table 2, it can be seen that the Young's modulus and strength of the composite material of the present invention is increased and the damping ratio is increased, and the density of the composite material of the present invention is about 6% lower than the conventional. Can be.

Accordingly, the tool holder having a composite material having such mechanical properties is capable of more precisely performing the machining of the hole of the workpiece without chattering at high speed since the damping ratio is large and the natural frequency is increased as compared with the conventional art. .

In addition, since the density of the composite part of the present invention is lower than in the related art, the overall weight of the tool holder can be lowered, thereby reducing the burden on the machine tool for mounting the tool holder and reducing the volume of the machine tool.

In addition, any one of the tool head 110, the core shaft 120, and the metal cover 140 may be prepared by surface heat treating titanium with a catalyst before assembling, and the titanium nano heat treatment may have a treatment time of 10 minutes to 6 minutes. The processing time is short with time, and because the processing temperature is relatively low at 430 to 600 degrees, there is an advantage that deformation or dimensional change of the material does not occur.

In addition, since titanium diffuses under the material surface during titanium nano heat treatment, the hardness is improved and the service life is extended due to the outstanding improvement in wear resistance, toughness, heat resistance and corrosion resistance of titanium.

That is, the surface hardness of the material after heat treatment of titanium nano may vary depending on the material, but in the case of tool steel, it has a high hardness of HV1200 to 1500 (Rockwell hardness 72 to 75HRc), and its depth also forms a deep diffusion layer of about 75 to 125 microns. Done.

On the other hand, cantilever-type line boring bar tool holders are guided through the bushing during machining. In this case, high surface hardness is required, and when the misalignment occurs, the boring bar tool holder is frequently bent due to collision with the bush. In general, a tool holder material used is nitrided or carburized steel, which has a low hardness and a low modulus of elasticity in the core and a general steel.

 At this time, instead of performing nitriding or carburizing treatment on the outside using alloy steel having high modulus of elasticity, when titanium nano-heat treatment is performed on the metal cover part inserted to cover the composite part of the tool holder, the modulus of elasticity is further reinforced to prevent bending. Boring bar tool holders with high hardness can be manufactured.

In addition, cutting tools such as boring bits or micro boring units are installed at the tip of boring bar tool holders, which are fixed in cantilever beams. When using alloy steel with high modulus of elasticity, the hardness of the connecting part connected to the machine tool is increased. Can't raise Therefore, carburizing or nitride steel should be used to increase the hardness of the joint without using alloy steel with high modulus of elasticity. However, chattering is likely to occur in the case of boring bar tool holders having a long diameter to diameter due to low modulus of elasticity. Is higher.

In this case, if the metal cover is made of alloy steel having a high modulus of elasticity and the metal cover is assembled to the composite material part, both conditions can be satisfied, and chattering occurs due to an increase in the modulus of elasticity of the tool holder. It raises the limit of the pressure, which makes it possible to perform stable machining.

While the invention has been shown and described with respect to particular embodiments, it will be understood that various changes and modifications can be made in the art without departing from the spirit or scope of the invention as set forth in the claims below. It will be appreciated that those skilled in the art can easily know.

1 is an assembly view showing a tool holder using a carbon nanotube composite material according to a first embodiment of the present invention.

2 is an exploded perspective view showing a tool holder using a carbon nanotube composite material according to a first embodiment of the present invention.

3 is an assembly view showing a tool holder using a carbon nanotube composite material according to a second embodiment of the present invention.

4 is an exploded perspective view showing a tool holder using a carbon nanotube composite material according to a second embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

100,100a: Tool holder 110: Tool head portion

112: cutting tool 114: guide pad

120: core shaft 130: composite material

140: metal cover 150: end portion

Claims (6)

A tool head portion having a replaceable at least one cutting tool for processing an inner circumferential surface of a hole formed in a workpiece; A core shaft of a predetermined length having one end assembled to the tool head; A composite material portion formed of a composite material in which the core shaft penetrates and is formed in close contact with one end of the tool head, and the carbon fiber epoxy and carbon nanotubes are mixed with each other; And Tool holder using a carbon nanotube composite material comprising a hollow cylindrical metal cover is inserted into the composite material to cover the entire outer surface or a portion of the outer surface of the composite material. The tool holder using a carbon nanotube composite material according to claim 1, wherein the composite material portion is formed of a hollow cylinder-shaped molded material using a mixture of 4 to 6 wt% carbon nanotubes mixed in carbon fiber epoxy. The tool holder of claim 1, wherein any one of the tool head part, the core shaft, and the metal cover is titanium nano-heat treated. The carbon nanotube composite material as claimed in claim 1, wherein the tool head part comprises at least one guide pad made of one of polycrystalline sintered diamond, cemented carbide, or cermet material to contact the inner circumferential surface of the hole to be machined. Tool holder using The carbon nanotube composite material of claim 1, further comprising an end portion inserted into and disposed at one end of the metal cover to be screwed with the other end of the core shaft to be tightly fixed to one end of the composite material. Tool holder used. A tool head portion having a replaceable at least one cutting tool for machining the inner circumferential surface of the hole formed in the object, a core shaft having one end assembled to the tool head portion, and a central hole into which the core shaft is disposed In the method of manufacturing a tool holder comprising a composite material portion formed to penetrate and tightly assembled to one end of the tool head portion and a metal cover inserted into the outer surface of the composite material portion, The composite material portion is made of a hollow cylinder shaped molding formed of a mixture of 4 to 6wt% carbon nanotubes in carbon fiber epoxy, and any one of the tool head, core shaft, and metal cover is heat treated with titanium nanos before assembly. Tool holder manufacturing method using a carbon nanotube composite material characterized in that.

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