KR20090089656A - Low noise cutting tool - Google Patents

Abstract

A low noise cutting tool reducing noise generated in a structure of shank in machining is provided to reduce machining noise of high strength by forming a shank welding a first metal plate and a second metal plate. A low noise cutting tool includes a shank(10) and a cutter unit. The shank has an axis hole(12) for connection with a rotary shaft. In order that the cutter water shift contacts the cut material, the material is prepared in the circumference of the shank. The shank comprises a first metal plate and a second metal plate. The first metal plate and the second metal plate have the mutually different thickness. The cutter water shift is a plurality of segments(20) adhered to the circumference of shank. A plurality of segment angle comprises the diamond particle.

Description

LOW NOISE CUTTING TOOL

The present invention relates to a low-noise cutting tool technology, and more particularly, to a technology that can reduce noise during cutting while having sufficient rigidity in a cutting tool having a lot of noise, such as a circular saw. It is about.

A cutting tool is a tool used for cutting that generates chips by giving a local shear deformation to a material, and includes, for example, a tool that uses particles and an edge, such as a diamond tool.

Cutting tools such as circular saws are used for cutting or grinding stone such as natural stone or concrete. In general, the circular saw is to cut the material through the rotational movement, causing a large noise due to its nature to damage the safety of workers and people around. As above, a tool, such as a circular saw, strikes the material while rotating at high speed, causing a large friction sound.

In general, a circular saw includes a shank made of one circular metal plate and a cutting tip attached to the outer periphery of the shank. Such circular saws generate a large friction noise due to the continual application of irregular bending loads to the cutting tips of the shank outer periphery away from the axis of rotation during cutting of the workpiece by rotation.

Accordingly, in the related art, a circular saw including a shank having a sandwich structure has been developed to reduce friction noise. The conventional circular saw includes a sandwich structure shank in which a copper plate is inserted between two circular metal plates having the same thickness. The two circular metal plates and the copper plates therebetween are joined by spot welding. This circular saw can reduce noise by attenuating the propagation of vibrations by partial confinement between the circular metal plates and the gaps between the metal plates in the microscopic view.

However, in the conventional circular saw, the rigidity is greatly reduced due to the small thickness of each of the circular metal plates having the same thickness, which is caused by the reduction of the cross-sectional secondary moment due to the decrease in the thickness of the circular metal plate. The low stiffness of the circular saw results in run-out failures when cutting the material and causes large cutting forces and jams due to the large displacement width of the outer diameter portion. For this reason, conventional circular saws having a sandwich structure are extremely limited in some cutting operations not subjected to heavy loads.

The technical problem of the present invention is to provide a low noise and high rigidity cutting tool having sufficient rigidity while reducing noise during cutting due to the structure of the shank in a rotary cutting tool with high noise like a circular saw. To provide.

According to an aspect of the present invention, there is provided a cutting tool comprising a shank having a shaft hole for connection with a rotating shaft, and a cutting means provided on the outer periphery of the shank to contact the material to be cut, the shank of the cutting tool is Since the first metal plate and the second metal plate having different thicknesses are joined to each other, noise can be reduced during cutting while having sufficient rigidity.

Preferably, a plurality of joints and voids exist between the first metal plate and the second metal plate, and the plurality of joints may be formed by spot welding.

Preferably, the cutting means is a plurality of segments attached to the outer periphery of the shank, each of the plurality of segments including diamond particles. More preferably, the shank has a circular outer circumference, and the plurality of segments are attached at regular intervals to the circular outer circumference with a thickness greater than the thickness of the shank. In addition, it is preferable that a plurality of slots are formed at regular intervals on the outer circumference of the shank to help discharge of the cutting chip.

The low noise cutting tool according to the present invention has sufficient rigidity while significantly reducing noise during cutting due to the shank structure formed by joining metal plates of different thicknesses. Accordingly, the low-noise cutting tool according to the present invention, unlike the circular saw of the conventional sandwich structure, which is limitedly used for cutting processing that does not require large rigidity, is capable of cutting processing requiring a large rigidity, thereby increasing the application width. In addition, the low-noise cutting tool according to the present invention can be widely used for cutting materials in civil engineering or construction sites, and can greatly reduce the noise generated at such construction sites, and accordingly, further by noise regulation. It can reduce the waste of cost due to the required soundproof wall construction.

In addition, the cutting tool according to the present invention using only two metal plates has another advantage in minimizing the economic losses due to the increase in the cost of subsidiary materials and the complicated manufacturing process, which is a problem of the conventional circular saw using three metal plates including a copper plate.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the cutting tool according to the present invention will be described with the circular saw as an example, but it is noted that the present invention is not necessarily limited to the circular saw described below.

1 to 3 show a circular saw in accordance with one embodiment of the present invention.

Referring to FIG. 1, the circular saw 1 of the present embodiment is a tool for cutting a material while being rotated by an electric motor, for example, and is attached to a circular shank 10 and an outer circumference of the shank 10. A plurality of segments 20 as cutting means to be included. The shank 10 has a shaft hole (12) in the center for coupling with the rotating shaft of the electric motor. In addition, a plurality of slots 14 are formed at regular intervals along the outer periphery of the shank 10, the plurality of slots 14 to facilitate the smooth discharge of the cutting chips generated during the material cutting process.

The plurality of segments 20 include artificial or natural diamond particles, and in the present embodiment, diamond particles and metal powder are appropriately mixed and manufactured by sintering the mixed particles. The plurality of segments 20 manufactured as described above are attached to the outer circumference of the shank 10 by, for example, silver soldering, brazing, or laser welding.

In addition, the thickness of the segment 20 is determined to be larger than the total thickness of the shank 10, which prevents under-cut of the segment and smoothly discharges the cutting chip from between the segments 20. Help. At this time, the total thickness of the shank 10 is determined by the sum of the thicknesses of the circular metal plates to be described below and the joint portion for joining the metal plates.

2 and 3, the circular shank 10 includes a circular first metal plate 10a and a second metal plate 10b, and includes the first metal plate 10a and the second metal plate ( 10b) is mutually joined by the some junction part 15 formed by the spot welding. At this time, the plurality of joining portions 15 are separated from each other between the first metal plate 10a and the second metal plate 10b with a predetermined thickness, and thus, the first metal plate 10a and the second metal plate ( There is an empty space 16 between 10b).

Circular saw 1 according to the present embodiment is a vibration and friction generated during cutting by the local restraint structure between the first metal plate 10a and the second metal plate 10b and the space 16 around it. Absorb noise. Moreover, since the hardness difference between the some joining part 15 formed by spot welding and the metal plate 10a, 10b which is a base material is small, the said circular saw 1 is also high in stability by an external load and an impact. In addition, the fine pores 16 of the first metal plate 10a and the second metal plate 10b may reduce reverberation time for the metal plates 10a and 10b to vibrate due to mutual interference when the metal plates 10a and 10b vibrate. Suppresses vibration to maximize noise attenuation.

According to the invention, the thickness of the first metal plate 10a is greater than the thickness of the second metal plate 10b, which is applied to the rigidity of the circular saw 1, in particular to the segment 20 away from the shaft hole 12. The rigidity against the bending load is great. As is known, stiffness is a quantification of the degree to which a material resists a given load when loaded from the outside of the material. Further, the stiffness of the circular saw 1 is proportional to the product of the Young's modulus determined by the materials of the first and second metal plates 10a and 10b and the cross-sectional secondary moment. Therefore, the greater the thickness of the shank 10, the higher the cross-sectional secondary moment and the rigidity of the circular saw 4. However, when the shank 10 is composed of the first and second metal plates 10a and 10b of different thicknesses bonded to each other, the thickness of the first metal plate 10a having a large thickness is explained below. ) Mainly affect the stiffness.

More specifically, the first metal plate 10a and the second metal plate 10b will have different bending loads even if their materials are the same due to different thicknesses. For example, even if a stress of at least yield strength is generated in the second metal plate 10b having a small thickness, the shank 10 is less than a yield strength in the first metal plate 10a having a large thickness. ) Does not cause plastic deformation, and the shank 10 is plastically deformed only when a stress of more than a yield strength is generated in the first metal plate 10a. This means that the circular saw 1 has improved rigidity than the conventional low noise circular saw by the first metal plate 10a which is geometrically more stable than the second metal plate 10b due to its large thickness.

In order to confirm the stiffness increase of the circular saws including shanks of metal plates of different thicknesses, experiments and numerical analyzes were conducted in parallel. The experimental results are shown in [Table 1] below, and the analysis results by numerical analysis are shown in [Table 2].

The experiment adopted a three-point bend test derived from ASTM Standard E850-90 Test Method B. Specimen dimensions were 50L × 10W × 2.7T and a numerical model was applied based on a 9 inch circular saw. A constant external load condition was applied to the circular saw, and as a restraint condition, the outside of the shaft hole was completely restrained. The thickness ratio between the two metal plates was analyzed by changing them as shown in [Table 2].

[Comparison of Mechanical Properties by Experiments] division Metal Plate Thickness (mm) + Metal Plate Thickness (mm) Metal Plate Thickness Ratio Lateral modulus of elasticity (N / mm ² ) percentage(%) Comparative example 1.35 + 1.35 50: 50 61127.31 100.0 Example 1 1.0 + 1.7 37: 63 66773.39 109.2

[Numerical Analysis Results by FEM] division Metal Plate Thickness (mm) + Metal Plate Thickness (mm) Metal Plate Thickness Ratio Displacement (mm) percentage(%) Comparative example 1.35 + 1.35 50 + 50 9.14931 100.0 Example 1 1.0 + 1.7 37 + 63 8.00337 87.4 Example 2 0.7 + 2.0 26 + 74 6.62044 72.4

From the results in [Table 1] above, when the metal plates of different thicknesses were bonded, it was confirmed that the lateral elastic modulus increased compared with the case of the metal plates of the same thickness, and from the results of [Table 2] As the difference in the thickness of the larger the displacement due to the load was confirmed to be reduced. This shows that a circular saw using shanks made by joining metal plates of different thickness is more rigid than a circular saw using shanks made by joining metal plates of the same thickness.

Table 3 below shows the results of the equivalent noise level measurement through frequency analysis. As the work material, granite was used, and the machine specifications and operating conditions were set to 30HP power, 2,000RPM, feed rate 2m / min, and cutting depth 40mm.

[Noise measurement] division rescue Noise (dB) Lmax (dB) Lmin (dB) Leq (dB) percentage(%) Comparative Example 1 Single metal plate shank 74.9 96.8 94.3 94.7 137.8 Comparative Example 2 Sandwich Structure Shank 74.9 90.7 87.7 89.3 100.0 Example Thickness ratio 38: 62 metal plate shank 74.9 90.8 87.8 89.5 101.4

From the results in [Table 3], compared to the conventional noise-producing circular saw (Comparative Example 1) containing a shank made of a single metal plate, the thickness of the metal sheet having a thickness ratio different from that of the circular saw (Comparative Example 2) including a shank of sandwich structure All of the circular saws (Examples) including the shank, it was confirmed that the noise level was remarkably low in the high frequency region. In addition, the circular saw of the present embodiment including the shank of the metal plate having a different thickness ratio exhibits substantially the same noise level as the circular saw of the sandwich structure, which is known to have very good noise reduction characteristics, and it can be confirmed that the noise reduction effect is also great.

FIG. 4 is a graph showing noise measurement results. FIG. 4 shows that a circular saw using a shank of a metal plate having a different thickness, which is a developed product, uses a shank of a single metal plate, similar to a conventional low noise product having a sandwich structure. It can be seen that the noise reduction effect is greater than the saw.

On the other hand, the cutting performance of the circular saw was confirmed by changing the cutting conditions to 2m / min, 3m / min and 4m / min in the feed rate similar to the above noise measurement experiment. The cutting performance was evaluated by measuring ampere changes during cutting using a dynamometer, and the results are shown in [Table 4]. The measured ampere was found to be about 13% less developed than conventional low noise products.

Cutting Performance Test division 1st_2m / min 2nd_3m / min 3rd_4m / min Ampere, A Comparative Example 2 (50: 50) 13.7 17.7 20.2 Example (38: 62) 11.4 15.7 17.9

1 is a plan view showing a cutting tool according to an embodiment of the present invention.

Figure 2 is an exploded perspective view showing a cutting tool according to an embodiment of the present invention.

3 is a sectional view taken along the line I-I of FIG.

Figure 4 is a graph for comparing and comparing the noise level of the low noise cutting tool and the existing cutting tool of the present invention.

Claims (6)

Shanks having shaft holes for connection with a rotating shaft; And Including a cutting means provided on the outer periphery of the shank, in contact with the material to be cut, The shank is a low noise cutting tool, characterized in that the first metal plate and the second metal plate having a different thickness are bonded to each other. The low noise cutting tool according to claim 1, wherein a plurality of joining portions and voids exist between the first metal plate and the second metal plate. The low noise cutting tool according to claim 2, wherein the plurality of joining portions are those formed by spot welding. The low noise cutting tool according to claim 1, wherein the cutting means is a plurality of segments attached to an outer circumference of the shank, and each of the plurality of segments includes diamond particles.  The low noise cutting tool according to claim 4, wherein the shank has a circular outer circumference, and the plurality of segments are attached to the circular outer circumference at regular intervals with a thickness greater than that of the shank. The low noise cutting tool according to claim 1, wherein a plurality of slots are formed at a predetermined interval on an outer circumference of the shank to help discharge the cutting chip.

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