KR100431583B1 - Bonding Composition for Cutting Tip and Cutting Tip and Cutting Wheel Using the Composition - Google Patents

Abstract

The present invention relates to a grinding wheel including grinding particles such as diamond or cubic boron nitride (CBN) for processing cutting tools such as drills, reamers, and end mills made of cemented carbide or tool steel. It is an object of the present invention to provide a bond composition capable of improving grinding performance and life and a grinding tip and a grinding wheel having improved grinding performance and life.

The present invention relates to a bond composition used for a grinding tip using diamond or cubic boron nitride as grinding particles,

The main components are a bond composition for a grinding tip composed of tin (Sn): 60 to 90% and antimony: 40 to 10%, and a grinding tip and a grinding wheel using the same.

Description

Bond composition for grinding tip and grinding wheel using the composition {Bonding Composition for Cutting Tip and Cutting Tip and Cutting Wheel Using the Composition}

The present invention relates to a grinding wheel for processing a cutting tool such as drill, reamer, end mill made of cemented carbide or tool steel including grinding particles such as diamond or cubic boron nitride (CBN). The present invention relates to a bond composition for a grinding tip and a grinding tip and a grinding wheel using the same, which can improve the grinding wheel and improve its grinding performance and service life by preventing dropping.

Grinding wheels for cutting tools such as drills, reamers and end mills made of cemented or tool steel are largely composed of grinding tips containing grinding particles such as diamond or cubic boron nitride (CBN) and shanks (cores) that hold them. consist of.

The grinding tip includes the grinding particles, a bond composition, and / or a filler.

The grinding wheel (diamond grinding wheel) is a material that serves to support the diamond at the grinding tip, that is, the resin wheel (resin wheel), the metal wheel (metal wheel) and the vitrified bond wheel (vitrified wheel) largely depending on the bond Diamond grinding wheels for cutting industrial tools and cutting tools such as drills, reamers and end mills are generally used as diamond grinding wheels made of resin and metal binders.

The grinding wheel is exposed to new diamonds by friction with the workpiece during processing, where the bonds used as binders are worn by the grinding chips to facilitate the exposure of these diamonds and also prevent the diamonds from falling off easily. It plays a role of smoothing the workpiece by fixing the diamond.

In general, resin bonds have low hardness and are easily abraded by grinding chips, so they are easy to expose to diamonds, so they have better grinding properties than metal bonds, but diamonds are easier to fall off, resulting in shorter lifespan and metal bonds with higher hardness values. Compared to resin bonds, diamonds are more difficult to protrude, leading to less grinding. However, diamonds are difficult to fall off.

In the case of the resin bond wheel, a filler other than diamond or cubic boron nitride (CBN), which is a phenol or polyimide-based resin constituting the bond, and grinding particles, and a ceramic such as silicon carbide (SiC), iron oxide, copper, silver, etc. Or metal powder may be added.

The filler added as described above serves to improve the performance of the diamond grinding wheel using a resin bond, such as improving the polishing efficiency due to a chemical reaction with the workpiece, adjusting the strength of the bond as a binder or improving the thermal conductivity efficiency.

In addition, in some cases, pores are artificially contained in the bond to improve grinding performance.

The resin bond wheel is manufactured by sintering mainly by hot press in the sintering temperature range of 150 ℃ to 300 ℃.

On the other hand, the metal bond wheel is basically a metal of one of iron, copper and nickel is 50% or more of the weight of the metal bond (binder), the rest is composed of one or two of the two metals or tin, lead, silver And other additive metals are added in appropriate proportions.

As an example, a copper-based metal bond consists of 70 to 90% copper and 10 to 30% tin by weight or 45 to 75% copper, 20 to 35% tin, 5 to 20% titanium. And other metals such as silver and lead.

In the case of the metal bond, like the resin bond, in order to improve the properties of the bond, a small amount of dissimilar metal (additive) may be added, or a ceramic powder such as silicon carbide or a metal inclusion may be added as a filler.

The metal bond wheel is generally manufactured by sintering at 500 to 1000 ° C. using a medium frequency sintering machine. In some cases, the metal bond wheel may be manufactured using a vacuum or hydrogen furnace.

Resin bond wheels and metal bond wheels may be mainly used for groove (flute) processing of cutting tools such as drills, reamers, and end mills made of high speed oral or cemented carbide, but resin bond wheels having excellent grinding properties are mainly used.

Unlike the general grinding operation, such a groove processing has a very deep cutting depth, so that the groove depth to be processed may reach 4 to 6 mm.

In order to process these grooves at once, the friction and the increase of the friction cause the oxidation of the bond and the workpiece, and the parts that fix the main shaft of the equipment to which the wheel is attached when the equipment is stopped or severely caused by excessive stress generated during grinding. It can be damaged by excessive stress.

Therefore, in order to process such a groove, work several times or grind with deep indentation at a time, but at a lower feed rate.

However, when working several times, problems with roughness, dimensions and performance of the workpiece may occur. In most cases, the groove is machined by one infeed, and the conventional resin bond grinding wheel has a feed speed of 20 mm / Do not exceed min

In addition, the development of higher horsepower than ever before has been required to improve the performance of the grinding wheel using diamond and cubic boron nitride, but the current resin bond wheels and metal bond wheels do not meet these requirements. .

The present invention is to study and experiment to solve the above problems of the prior art, and to propose the present invention based on the results, the present invention by properly mixing tin and antimony to improve the grinding performance and life of the grinding wheel It is an object of the present invention to provide a bonding composition which can be improved and a grinding tip and a grinding wheel having improved grinding performance and lifespan, which are manufactured using the same.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

The present invention relates to a bond composition used for a grinding tip using diamond or cubic boron nitride as grinding particles,

The present invention relates to a bond composition for a grinding tip composed of tin (Sn): 60 to 90% and antimony (Sb): 40 to 10% by weight.

In addition, the present invention is one or two or more selected from the group consisting of additives consisting of copper, silver, zinc and iron in the bonding composition for the grinding tip is further contained in the range of less than 20% of the total bond components in weight% and / or carbonized The present invention relates to a bond composition for a grinding tip, in which at least one selected from the group consisting of boron, silicon carbide, titanium oxide, and metal oxide is further contained in a range of 30% or less of the total grinding tip volume.

The present invention also provides a grinding tip for a grinding wheel comprising a grinding particle and a bond comprising one or two kinds of diamond and cubic boron nitride, wherein the bond is a grinding tip for a grinding wheel comprising the bond composition for the grinding tip of the present invention. It is about.

Further, in a grinding wheel comprising a grinding tip and a shank (core), the grinding tip relates to a grinding wheel comprising the grinding tip for a grinding wheel of the present invention described above.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The bond composition of the present invention is preferably applied to the bond composition used in the production of a grinding tip and a grinding wheel for processing a cutting tool such as a drill, a reamer or an end mill.

Bond composition for the grinding tip of the present invention is a kind of metal to compensate for the defects of the resin bond and metal bond used in the manufacture of the grinding tip, the hardness and physical properties of the tin similar to the resin as a base metal and an appropriate amount of Antimony is added and configured.

In addition, the additive composition and / or filler made of other alloying elements may be further added to the bond composition for the grinding tip of the present invention.

Hereinafter, the components constituting the bond composition for the grinding tip of the present invention and the reason for selecting the content of these components will be described.

The tin is a metal having a melting point of 231.9 ° C. and a Brinell hardness of 10 to 22, and having a lower melting point and hardness than other metals, high malleability and excellent corrosion resistance, and is mainly an alloy element of other metals such as solder, metal type, bearing, and jewelry. It is being used.

As mentioned above, the conditions of the bond should be worn by the workpiece to cause protrusion of the diamond or cubic boron nitride, which is the abrasive grain, and the protruding diamond or cubic boron nitride should not be easily dropped and kept long. .

Tin has a low hardness value and is easily worn when rubbing against the workpiece, thereby facilitating protrusion of the diamond.

However, when the diamond is stressed during grinding, the low hardness and high malleability of tin can easily cause the protruding diamond to fall off or sink back into the bond base. As a result, the grinding wheel loses its grinding force. Falling and at the same time have a low life.

Therefore, in this invention, tin was made into a basic bond component, and antimony was added to it. The added antimony improves the hardness value of tin, which is a basic ingredient, to suppress bond wear, and the alloy of antimony and tin produced in the tin base acts as an inclusion in the highly malleable tin base so that the diamond rubs against the workpiece. It prevents the diamond from sinking due to the stress generated at the same time, and also maintains the diamond protruding from the surface layer of the bond in the diamond tool.

In the present invention, when the content of tin is less than 60%, 80 to 90% of the total volume is present as an alloy of tin and antimony by the reaction with antimony during sintering, and only 10 to 20% remains as tin.

Therefore, the bonding force between the abrasive particles such as diamond and the bond is lowered, the bond layer is easily broken or broken even if a slight impact or stress is applied, the diamond is easily dropped.

In addition, when the tin content is greater than 90%, the bond itself is low in hardness, so that the bond layer is easily worn during grinding and diamond depression occurs.

Therefore, in the present invention, the content of tin is preferably set to 60 to 90%.

The bonding layer has a degree of bonding due to diffusion between the bond components according to the sintering temperature and pressure, and also the porosity of the bond layer.

In the present invention, the porosity of the inside of the bond layer is preferably set to 5 to 20%, because it shows the best grinding performance in this range.

In the present invention, in order to improve the performance of the grinding wheel, one or two or more selected from the group consisting of copper, silver, zinc, and iron, as well as tin and antimony, may be added as components of the bond.

Since the additives have higher hardness than tin, as the content of these additives increases, the hardness value of the grinding tip is improved to improve the life, while increasing the grinding load and decreasing the grinding performance.

Therefore, in the present invention, in consideration of the properties of the above-described additives, it is preferable to set the addition amount to 20% or less of the total bond by weight%.

That is, when the amount of the additives exceeds 20%, the life is extended, but the grinding performance is greatly reduced, it is preferable to set the added amount to 20% or less of the total bond by weight%.

In the present invention, one or more selected from the group consisting of boron carbide, silicon carbide, titanium oxide and metal oxides may be added in a range of 30% or less of the total grinding tip volume.

The fillers themselves act as excellent grinding particles in the bond and at the same time serve to suppress the wear of the bond, but when the amount is too large, the grinding performance is increased due to the increase of the grinding load due to friction with the workpiece. It is desirable to limit the addition amount to 30% or less of the total grinding tip volume since it will lead to a decrease.

As described above, the grinding tip produced using the bond composition according to the present invention improves the protrusion and retention of diamond compared to the conventional resin bond wheel or metal bond wheel, so that the grinding wheel having the grinding tip of the present invention Excellent performance compared to conventional grinding wheels.

Grinding tip in accordance with the present invention is produced by press sintering by mixing the bond composition of the present invention and the grinding particles consisting of one or two of the diamond and cubic boron nitride.

In the grinding tip of the present invention, the concentration of the grinding particles (diamonds and cubic boron nitride) can be selected according to conventional conditions, and the preferred concentration is about 50 to 125.

It is preferable that the sintering temperature at the time of manufacture of the grinding tip of this invention is set to 190-220 degreeC, and the press pressure is set to 150-400 kg / mm <^2> .

The grinding wheel of the present invention is manufactured by combining the grinding tip of the present invention manufactured as described above with a shank (core).

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

A diamond grinding wheel with a diameter of 160 mm was fabricated using a bond consisting of 70 wt% tin and 30 wt% antimony. In this case, nickel coated diamond was used as the grinding particles, and boron carbide (B ₄ C) was added as a filler.

The diamond was added into the bond to have a particle size of 120/140 mesh to 15% (concentration 60) of the total volume of the grinding tip, and boron carbide was added to be 25% of the total tip volume.

In addition, in order to facilitate bonding of the bond and the shank, which is the body of the tool, the shank was also produced by hot press sintering using powder in which tin and antimony were mixed in the same mixing ratio as the bond. At this time, the shank and the grinding tip were joined by mutual diffusion, and the sintering temperature and the pressure were 215 ° C and 350kgf / cm ² , respectively.

And the sample produced in this example has a porosity of 10%.

The porosity was adjusted by applying the pressure applied during sintering by dividing the primary pressure and the secondary pressure in accordance with the rise in temperature.

The polishing wheel (inventive wheel) manufactured in this way, a conventional resin bond wheel using polyimide resin, and a conventional metal bond wheel made of copper: 70% by weight, tin: 25% by weight, and other additive metals: 5% by weight. The grinding test was performed using MFG-II equipment (manufactured by Makino Seiki Co., Ltd.), and the results are shown in Table 1 below.

The workpiece used in the grinding test was a cemented carbide (tungsten carbide) round bar having a diameter of 19.04 mm, and the hardness was HRA 94.

In Table 1 below, x denotes a case where a grinding defect occurs due to burning or wheel breakage, and O denotes normal grinding (within a maximum of 1 Kw of grinding load).

Grinding condition Conventional resin bond wheel Conventional Metal Bond Wheel Invention Wheel Infeed (mm) Table Feed Speed (mm / min) Spindle Speed (RPM) One 2 100 2000 ○ × ○ 2 4 10 2000 ○ × ○ 3 4 20 2000 × × ○ 4 4 200 2000 × × ○

As shown in Table 1, in the case of conventional resin bond wheels, grinding is normally possible until the cutting speed is 4 mm and the feed rate is 10 mm / min. Grinding defects were confirmed to be caused by the phenomenon that the surface of the wheel is severely oxidized (burning phenomenon) due to the increase of the grinding load and frictional heat.

In addition, the grinding failure occurs in the case of the conventional metal bond wheel, which was confirmed to be due to severe grinding load.

On the contrary, it can be seen that the present invention wheel manufactured using the bond composition according to the present invention can be ground at a feed rate of 200 mm / min when the depth of cut is 4 mm in the groove grinding of the cemented carbide end mill.

This is about 4 times the performance improvement compared to the maximum transfer speed of 100mm / min when the conventional resin bond wheel in 2mm in terms of performance.

However, considering that the conventional resin bond wheel has a feed speed of up to 10 mm / min when the cut resin is 4 mm in diameter, the performance of the 4 mm incision can be improved by about 20 times.

In addition, the protruding action of the diamond eliminates the need for dressing during the operation. The shape retaining performance of the grinding wheel is excellent, and the number of re-throughs is reduced by more than half compared to the conventional resin bond wheels, thereby improving the service life by more than two times. It became.

Example 2

To prepare a grinding wheel using the bond composition having the composition of Table 2, and then to investigate the life and grinding performance, the results are shown in Table 2.

In this case, nickel coated diamond was used as the grinding particles, and the volume of the diamond was 15% (concentration 60) of the total grinding tip volume, and the boron carbide filler was made to occupy 25% of the total volume.

The grinding performance of the following Table 2 is measured as in Example 1, and represents the symbol "○" normal grinding (within the grinding load up to 1Kw), and the symbol "x" indicates the case where the grinding failure due to burning or wheel breakage occurs. Indicates.

Psalm No. Bond composition (wt%) Life (Workpiece throughput / Tip wear) Grinding performance Sn Sb Comparative material 1 50 50 940 cm 2 / mm ○ Invention 1 60 40 1900 cm2 / mm ○ Invention 2 70 30 2350 ㎠ / mm ○ Invention 3 80 20 2100 cm2 / mm ○ Invention 4 90 10 1600 ㎠ / mm ○ Comparative material 2 95 5 - ×

As shown in Table 2, when the tin is less than 60% (Comparative Material 1), the grinding performance is good, but it can be seen that the life is drastically reduced, which is low bonding strength between the grinding particles and the bond such as diamond during sintering This is because the holding force of the grinding particles is weakened.

In addition, when the content of tin exceeds 90% (Comparative Material 2), the grinding operation was not possible due to clogging and an increase in the grinding load.

On the other hand, when manufacturing a grinding wheel using the bond composition according to the present invention (inventive material 1-4) it can be seen that both the life and the grinding performance is excellent.

Example 3

To prepare a grinding wheel using the bond composition, as shown in Table 3, to evaluate the grinding performance of the prepared grinding wheel, the results are shown in Table 3 below.

Nickel coated diamond was used as the grinding particles, and the amount of diamond used was about 15% (concentration 60) of the total grinding tip volume.

In addition, boron carbide was added as a filler to account for 25% of the total volume.

The cutting conditions were 4 mm in cut and 200 mm / min in feed rate.

In Table 3, x denotes a case where a grinding defect occurs due to burning or wheel breakage, and O denotes a normal grinding (within grinding load up to 1 Kw).

Psalm No. Bond composition (wt%) life span Workpiece throughput Tip wear amount) Grinding performance Sn Sb Cu Ag Comparative material 3 49 21 30 - - × Invention 5 56 24 20 - 2400 cm 2 / mm O Invention Material 6 56 24 10 10 2410 cm 2 / mm O Invention Material 7 59.5 25.5 10 5 2430 cm 2 / mm O Invention Material 8 63 27 10 - 2390 cm2 / mm O Invention Material 9 63 27 5 - 2360 cm 2 / mm O Invention Material 10 63 27 - 10 2410 cm 2 / mm O Invention Material 11 70 30 - - 2350 ㎠ / mm O

As shown in Table 3, when the copper and / or silver is added according to the present invention it can be seen that the life is improved.

However, in the case of adding copper and / or silver [invention material (5-10)], it was confirmed that the grinding performance is somewhat lower than the invention material 11 without the addition of copper and silver.

Example 4

In the bond composition having the composition of Inventive Material 11 of Table 3 of Example 3, boron carbide was contained as a filler to 20%, 25%, 30% and 35% of the total tip volume, and the grinding wheel was After the manufacturing, the grinding test was performed on each of the manufactured grinding wheels under the same conditions as in Example 3, and it was confirmed that the grinding load increased as the boron carbide content was increased. It is believed that the amount of boron carbide that participates in grinding is increased.

In particular, when the boron carbide exceeds 30%, the grinding phenomenon is not possible because the burning phenomenon of the surface oxidation of the workpiece and the wheel due to the grinding load appeared.

In the present embodiment, it was confirmed that the best grinding property when the amount of boron carbide is 20-25%.

As described above, the present invention provides a bond composition that can properly mix tin and antimony and improve the grinding performance and life of the grinding wheel, and a cutting tool such as a drill, reamer or end mill by providing a grinding wheel with improved grinding performance and life. It is effective to improve the production efficiency.

Claims (5)

In the bond composition used for the grinding tip using diamond or cubic boron nitride as the grinding particles, Bond composition for grinding tips, characterized in that the composition is 60% to 90% tin and 40% to 10% antimony in weight%. The bonding composition for a grinding tip according to claim 1, wherein one or two or more selected from the group consisting of copper, silver, zinc and iron are further contained in an amount of 20% or less of the total bond components by weight. The method according to claim 1 or 2, wherein one or more selected from the group consisting of boron carbide, silicon carbide, titanium oxide and metal oxide is further contained in the range of 30% or less of the total grinding tip volume. Bond composition for grinding tips In the grinding tip for a grinding wheel comprising a grinding particle and a bond comprising one or two kinds of diamond and cubic boron nitride, Grinding tip for grinding wheel, characterized in that the bond consists of a bond composition for the grinding tip of any one of claims 1 to 3. A grinding wheel comprising a grinding tip and a shank (core), wherein the grinding tip comprises a grinding tip for a grinding wheel of claim 4