KR102465876B1 - Cutting Tools With Improved Clamping Force - Google Patents

Abstract

The present invention relates to a cutting tool having a shank part and fixed to a tool holder, wherein a plurality of crater-shaped protrusion parts are formed on a surface of the shank part, thereby improving a fastening force of the cutting tool. The cutting tool according to the present invention comprises the shank part fixed to the tool holder, wherein a plurality of concave-convex parts having a core-rim structure are formed on the surface of the shank part. Moreover, a rim of the core-rim structure forms a protruding shape compared to the surface of the shank part and the core in a crater shape. Accordingly, the cutting tool has a surface structure that gives excellent fastening force when fastened to a tool holder on the surface of the shank part.

Description

Cutting Tools With Improved Clamping Force}

The present invention relates to a cutting tool having a shank and fixed to a tool holder, and to improve the fastening force of the cutting tool by forming a plurality of crater-shaped protrusions on the surface of the shank.

Cutting tools used for various cutting processes such as milling, drilling, boring, and hobbing are used in a fixed state in the tool holder. Accordingly, the cutting tool is formed with a shank for fixing to the tool holder.

However, there is a problem in that a strong thrust is applied during cutting, and vibration is generated due to a minute gap formed between the cutting tool and the tool holder, so that the cutting quality of the workpiece is deteriorated.

In order to improve this problem, a method of forming fine concavities and convexities by colliding hard particles on the surface of the shank of a conventional cutting tool is partially used. have.

In addition, a method of forming a structure to improve the fastening force through mechanical processing on the shank may be used, but this method increases the manufacturing cost of the cutting tool or complicates the operation due to the introduction of an additional machining process and the complexity of the structure There is a problem with doing it.

Korean Patent Publication No. 2009-0005372

An object of the present invention is to improve the problems of the prior art described above, and an object of the present invention is to provide a cutting tool having a surface structure that provides excellent fastening force when fastened to a tool holder on the surface of a shank.

In order to achieve the above object, the present invention provides a cutting tool having a shank portion fixed to a tool holder, wherein a plurality of concavo-convex portions having a core-rim structure are formed on the surface of the shank portion, and the core-rim The rim of the structure has a crater shape and protrudes compared to the surface and the core of the shank, and the composition of the rim is different from that of the surface and the core of the shank.

The cutting tool according to the present invention provides excellent fastening force when the shank part is fastened to the tool holder to suppress vibration of the cutting tool during cutting, thereby further improving the machining quality of the workpiece compared to the prior art.

1 is a view of a cutting tool having a shank portion.
2 is a schematic view showing that a crater-type uneven structure is formed in a spiral pattern on the surface of the shank of the rotary cutting tool.
3 is a microstructure image of a crater-type concave-convex structure for improving fastening force formed on the surface of a shank according to an embodiment of the present invention.
4 is a result of performing component analysis on a rim region, a core region, and a shank surface region of a crater-type uneven structure for improving fastening force formed on the surface of the shank according to an embodiment of the present invention.

Hereinafter, the configuration and operation of the embodiment of the present invention will be described with reference to the accompanying drawings. In the following description of the present invention, if it is determined that a detailed description of a related well-known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, when a part 'includes' a certain component, this means that other components may be further included, rather than excluding other components, unless otherwise stated.

A cutting tool according to the present invention includes a shank portion fixed to a tool holder as shown in FIG. 1, and a plurality of irregularities having a core-rim structure are formed on the surface of the shank portion, The rim of the core-rim structure has a crater-shaped shape that protrudes compared to the surface and the core of the shank, and the composition of the rim is different from that of the surface and the core of the shank.

The concave-convex portion according to the present invention has a core-rim structure and has a crater-shaped rim that protrudes compared to the surface of the core or shank. At the same time, by controlling the physical properties of the rim by adjusting the composition of the rim to be different from the surface of the core or the shank, the fastening force with the tool holder can be further improved.

In addition, the shank of the cutting tool is made of, for example, cemented carbide in which tungsten carbide (WC) particles are bonded by a metal binder, and the protruding rim (region) may have a higher tungsten content than the surface of the core or shank. . A high tungsten content in the rim means a relatively low binder content in the rim. As such, when the binder content in the rim (region) is reduced, the modulus of elasticity of the rim is lowered, which is advantageous in suppressing vibration of the cutting tool.

In addition, the diameter of the rim may be 5 ~ 100㎛, and the protrusion height of the rim may be 0.1 ~ 5㎛ based on the shank surface.

If the diameter of the rim is out of the range of 5 ~ 100㎛, it is difficult to obtain the desired effect in the present invention, and the more preferable diameter of the rim is 10 ~ 70㎛. Similarly, when the protrusion height of the rim is out of the range of 0.1 to 5 μm, it is difficult to obtain the effect such as reduction of vibration desired in the present invention, and the protrusion height of the rim is more preferably 0.5 to 2 μm.

In addition, the metal binder may be made of cobalt (Co), the core may have a higher content of cobalt (Co) than the rim, and the depth of the core may be 5 μm or less from the protrusion of the rim. At this time, the content of cobalt in the rim is preferably less than 1% by weight, preferably 1.5% by weight or more compared to the surface area of the core or shank.

As such, when the cemented carbide is made of a WC-Co alloy, the cobalt (Co) (ie, binder) content of the core is preferably maintained higher than that of the rim, and when the depth of the core exceeds 5 μm, vibration is suppressed Since the effect falls, it is preferable that it is 5 micrometers or less.

In addition, along the outer periphery of the shank, the concave-convex portion having the core-rim structure may be formed in a spiral shape.

The core-rim structure formed on the outer periphery of the shank may be formed to form an irregular or regular pattern. At this time, in the case of a rotary cutting tool, if the core-rim structure is arranged in a spiral as shown in FIG. can

[Example]

Cutting tool manufacturing process

In order to increase the clamping force between the cemented carbide cutting tool and the holder, the shank of the cutting tool was exposed to a laser to form a certain pattern on the surface of the shank. These patterns and detailed structures are shown in FIGS. 2 and 3 .

Specifically, a cemented carbide end mill composed of WC and Co or tarcarbide, ball type diameter 8mm, shank diameter 8mm, total length 110mm While rotating the cutting tool at a constant speed, the laser irradiation conditions (W, Hz, Head Speed, Distance, etc.) are adjusted. The cemented carbide cutting tool shank was irradiated. The laser conditions may vary depending on equipment characteristics and conditions. The surface of the cemented carbide shank exposed to the laser may have a different structure depending on the laser irradiation conditions. Detailed laser conditions were performed with Table 1 below.

division Laser processing conditions Shank surface condition W Hz Head Speed
(Hz) Distance
(um) Rz
(μm) type hole/core
size hole/core depth prior art Not applicable 0.55 - - - Comparative Example 1 100 1000 500 20 7.29 hall 87 20.9 Comparative Example 2 70 1000 1000 5 4.79 hall 65 15.8 Comparative Example 3 30 1000 500 20 4.71 hall 78 18.0 Comparative Example 4 15 2000 1500 10 4.54 hall 27 9.5 Comparative Example 5 45 800 500 5 5.22 hall 90 15.1 Example 1 45 625 1500 20 2.24 core to rim 65 6.91 Example 2 20 625 1000 10 1.87 core to rim 30 3.5 Example 3 15 800 500 20 2.49 core to rim 17 13.2

As can be seen in Table 1, the shank surface pattern structure of Examples 1 to 3 of the present invention shows a core-rim structure, and it can be seen that there is a difference from the shank part hole pattern structure of the comparative example. That is, it could be controlled to have a core-rim structure on the surface by controlling the laser irradiation condition applied to the surface of the shank of the cutting tool.

microstructure

Through the above process, the surface of the sample in which the concave-convex part of the core-rim structure was formed on the surface of the shank part was observed with an electron microscope, and components of the core, rim, and surface area were analyzed.

3 is a microstructure image of a crater-type uneven structure for improving fastening force formed on the surface of the shank according to an embodiment of the present invention, and FIG. 4 is a fastening force formed on the surface of the shank according to an embodiment of the present invention. It is the result of performing component analysis on the rim region, the core region, and the shank surface region of the crater-shaped concavo-convex structure.

As can be seen in FIG. 3 , a rim that appears as a red ring-type on the surface of the shank of the cutting tool according to an embodiment of the present invention and a core consisting of a yellow-centered tissue inside the rim ), it can be seen that the formed core-rim tissue is formed.

In addition, as confirmed in FIG. 4, the cobalt content of the rim region is 1 wt%, while the tungsten (W) content is high, and the cobalt content of the core region is 5 wt%. is relatively high, and the cobalt content of the shank surface area was 3% by weight. As such, when the content of cobalt (that is, binder) in the rim region is lowered, the elastic modulus of the rim region in direct contact with the tool holder is lowered, so that vibration of the cutting tool by the rim can be more suppressed. there will be

On the other hand, the measured height of the rim was measured to be in the range of 1 to 5 μm, and the maximum depth of the multiple cores was measured to be in the range of 2 to 10 μm from the protrusion of the rim.

Cutting performance evaluation

In general, when machining a high-hardness workpiece, the main wear of the cutting tool is chipping due to the repeated vibration of the workpiece and the tool and the impact of the cutting edge. Therefore, it can be said that the clamping force between the cutting tool and the holder is a big variable in the evaluation of chipping resistance. In Tables 2 and 3 below, the chipping resistance of Comparative Examples and Examples is shown as a result of evaluation of high hardness end mill cutting performance, and the conditions for evaluation of cutting performance are as follows.

- Workpiece: SKD11

- Model number: PBE2080-100-S08 (PVD grade - TiSiN-based thin film applied)

- Vc : 115 m/min

- fn : 0.12 mm/Tooth

- ap : 0.4 mm

- ae: 0.5 mm

division Shank surface cutting life
(Processing amount cm ³ ) wear type situation hole/core
size
(μm) Rim overhang
(μm) Hole/Core Depth
(μm) test 1 test 2 prior art - - - - 3,600 3,960 Wear
chipping Comparative Example 1 hall 72 to 95 0 15.1 to 32.9 2,880 2,160 chipping
damage Comparative Example 2 hall 50 to 80 0 11.8 to 18.5 3,240 3,420 Wear
chipping Comparative Example 3 hall 63 ~ 93 0 9.7 to 23.0 2,880 3,060 wear chipping Comparative Example 4 hall 15 to 34 0 6.8 to 13.6 3,780 3,060 wear chipping Comparative Example 5 hall 42 to 95 0 11.3 to 21.3 2,700 2,880 wear chipping Example 1 core to rim 42 to 83 1.1 to 4.8 3.5 to 8.91 5,760 5,040 Wear fine chipping Example 2 core to rim 28 to 52 0.8 to 3.2 2.7 to 6.91 4,320 4,680 Wear
fine chipping Example 3 core to rim 11 to 28 1.8 to 6.3 8.8 to 18.2 3,600 4,320 Wear
chipping

As can be seen in Table 2, Comparative Examples 1 to 5 of the present invention had inferior lifespan compared to the conventional examples in which laser treatment was not applied to the shank, but the shank of the cutting tool according to the conditions of Examples 1 to 3 was the holder's shank. The high bonding strength suppressed tremors and showed a superior lifespan compared to the prior art. Accordingly, the fastening force between the shank part and the holder can be controlled by the laser processing conditions, and the cutting tools according to the conditions of Examples 1 to 3 can be suitably used for machining a high-hardness workpiece.

In addition, the cutting performance of the cutting tools of Examples and Comparative Examples manufactured under the conditions shown in Table 1 with respect to the high-hardness workpiece was further evaluated under the following conditions.

- Workpiece: STAVAX

- Model number: PBE2080-100-S08 (PVD grade - TiSiN-based thin film applied)

- Vc : 150 m/min

- fn : 0.15 mm/Tooth

- ap : 0.6 mm

- ae: 0.6 mm

division Shank surface cutting life
(Processing amount cm ³ ) wear type situation hole/core
size
(μm) Rim overhang
(μm) Hole/Core Depth
(μm) Test 1 Test 2 prior art - - - - 20,400 18,600 Wear
chipping Comparative Example 1 hall 72 to 95 0 15.1 to 32.9 18,600 14,400 chipping
damage Comparative Example 2 hall 50 to 80 0 11.8 to 18.5 16,800 13,200 Wear
chipping Comparative Example 3 hall 63 ~ 93 0 9.7 to 23.0 13,200 17,400 wear chipping Comparative Example 4 hall 15 to 34 0 6.8 to 13.6 18,000 17,400 wear chipping Comparative Example 5 hall 42 to 75 0 11.3 to 21.3 21,600 15,600 wear chipping Example 1 core to rim 42 to 83 1.1 to 4.8 3.5 to 8.91 26,400 24,600 Wear fine chipping Example 2 core to rim 39 to 52 0.8 to 3.2 2.7 to 6.91 25,200 22,800 Wear
fine chipping Example 3 core to rim 11 to 28 1.8 to 6.3 8.8 to 18.2 21,600 20,400 Wear
chipping

As can be seen in Table 3, the cutting tools according to Examples 1 to 3 of the present invention showed excellent performance and uniformity of quality due to high fastening force between the shank and the holder, but according to Comparative Examples 1 to 5 and the prior art. It was found that the specimen was terminated due to abnormal wear, and thus the cutting life and quality deviation were significantly inferior compared to the present invention.

surface roughness evaluation

In general, since the surface roughness of the workpiece decreases due to repeated impacts and vibrations between the workpiece and the tool during graphite machining, the clamping force between the tool and the holder is a big variable. In Table 4 below, the evaluation of the shank part laser treatment condition for Table 1 is shown as the evaluation result of the diamond-coated end mill. The cutting performance evaluation conditions are as follows.

- Workpiece: Graphite (HRc 47~52)

- Model number: DBE2030-060-V5N12S6

- Grade: ND3000 (G10E -Co 6% + MCD thin film)

- RPM : 30,000

- Feed : 3,000 mm/min

- ap : 0.1 mm

- ae: 0.05 mm

- Processing time: 60 minutes

division Shank surface condition Workpiece surface roughness
(Ra - μm) wear type type hole/core
size
(μm) Rim overhang
(μm) Hole/Core Depth
(μm) Test 1 Test 2 prior art - - - - 0.98 0.82 Wear
chipping Comparative Example 1 hall 72 to 95 0 15.1 to 32.9 1.23 1.42 chipping
damage Comparative Example 2 hall 50 to 80 0 11.8 to 18.5 1.18 0.99 Wear
chipping Comparative Example 3 hall 63 ~ 93 0 9.7 to 23.0 0.88 0.95 wear chipping Comparative Example 4 hall 15 to 34 0 6.8 to 13.6 0.80 0.93 wear chipping Comparative Example 5 hall 42 to 75 0 11.3 to 21.3 0.88 1.12 wear chipping Example 1 core to rim 42 to 83 1.1 to 4.8 3.5 to 8.91 0.54 0.70 Wear fine chipping Example 2 core to rim 39 to 52 0.8 to 3.2 2.7 to 6.91 0.45 0.55 Wear
fine chipping Example 3 core to rim 11 to 28 1.8 to 6.3 8.8 to 18.2 0.89 1.02 Wear
chipping

As can be seen in Table 4, it was confirmed that the cutting tools according to Examples 1 to 3 of the present invention exhibited excellent machining quality by suppressing vibration during graphite machining due to high fastening force between the shank and the holder. The specimens according to Comparative Examples 1 to 5 and the prior art exhibited a wear pattern similar to that of the Example, but had inferior surface roughness compared to the Example due to vibration. Accordingly, it was confirmed that the graphite finishing machining quality was improved by improving the clamping force between the tool shank and the holder.

Peel resistance evaluation

When machining a composite material (CFRP) with a diamond-coated cutting tool, peeling appears as a major wear tendency due to repeated impact and vibration of the cutting edge between the workpiece and the tool. Therefore, it can be said that the clamping force between the tool and the holder is a big variable that affects the adhesion between the diamond thin film and the base material. In Table 5 below, the evaluation of the shank part laser treatment condition for Table 1 is shown as the diamond coating drill evaluation result. The cutting performance evaluation conditions are as follows.

- Workpiece: CFRP (T700)

- Model number: MSDP0635-5C

- Grade :ND2100 (GK05 -Co 6% + FS thin film)

- RPM : 7,500

- Feed : 1,300 mm/min

- ap : 10 mm

- ae: 2.8 mm

division Shank surface condition cutting life
(Processing Hall) wear type type hole/core
size Rim overhang
(μm) Hole/Core Depth
(μm) test
One test
2 prior art - - - - 310 330 peeling
Wear Comparative Example 1 hall 72 to 95 0 15.1 to 32.9 150 220 peeling Comparative Example 2 hall 50 to 80 0 11.8 to 18.5 250 190 peeling Comparative Example 3 hall 63 ~ 93 0 9.7 to 23.0 220 220 peeling Comparative Example 4 hall 15 to 34 0 6.8 to 13.6 250 230 peeling Comparative Example 5 hall 42 to 75 0 11.3 to 21.3 150 180 peeling Example 1 core to rim 42 to 83 1.1 to 4.8 3.5 to 8.91 420 360 WearBurr Example 2 core to rim 39 to 52 0.8 to 3.2 2.7 to 6.91 380 400 Wear
Burr Example 3 core to rim 11 to 28 1.8 to 6.3 8.8 to 18.2 360 280 Wear
Burr

As can be seen in Table 5, the diamond-coated drills according to Examples 1 to 3 of the present invention showed a higher lifespan compared to the conventional examples due to normal flank wear in all CFRP cutting performance tests, but according to Comparative Examples 1 to 5 All diamond-coated drills were found to have a significantly lower cutting life compared to the present invention as their lifespan was terminated due to peeling.

From these results, it was confirmed that when the protrusion of the core-rim structure is formed on the surface of the shank by laser treatment, the fastening force between the shank and the holder can be further improved, and thus the processing quality can be improved.

Claims (5)

A cutting tool having a shank part fixed to a tool holder,
A plurality of irregularities having a core-rim structure are formed on the surface of the shank,
The rim of the core-rim structure has a crater-shaped shank surface and a protruding shape compared to the core,
A cutting tool, characterized in that the composition of the rim is different from that of the shank surface and the core. The method of claim 1,
The shank part is made of cemented carbide in which tungsten carbide (WC) particles are bonded by a metal binder,
Cutting tool, characterized in that the tungsten content of the protruding rim is higher than that of the surface of the core or the shank. The method of claim 1,
The diameter of the rim is 5 ~ 100㎛,
Cutting tool, characterized in that the protruding height of the rim is 0.1 ~ 5㎛ based on the surface of the shank. 3. The method of claim 2,
The metal binder is cobalt (Co),
The core has a higher cobalt (Co) content than the rim,
The depth of the core is a cutting tool, characterized in that 10㎛ or less from the protrusion of the rim. 5. The method according to any one of claims 1 to 4,
The cutting tool, characterized in that along the outer periphery of the shank, the concave-convex portion having the core-rim structure is formed in a spiral.

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