KR0167007B1 - Vitrified tool manufacturing method - Google Patents

Abstract

The present invention provides a method for producing a high quality non-tritiated tool with a high degree of defectivity while forming a pore of a tool by simply using water, and furthermore, by controlling the amount of water, According to the present invention, glass particles and 8-35% of water are put into a wet ball mill and pulverized to form a slurry. The slurry thus obtained is ground in a ball mill with diamond or CBN particles, Mixing the slurry with CMC and filling the slurry with the mixed slurry; molding the slurry in the mold while rapidly cooling the slurry while pressurizing with a hydraulic press at a pressure of 50-200 kg / m < 2 > And the dried molded article is heated in an electric furnace and maintained in a heated state, and then dried at room temperature The manufacturing method of a non-unified tree tool comprising the step of sintering is not provided by slow cooling.

Description

Manufacturing method of non-tritide tool

The present invention relates to a method of manufacturing a Vitrified tool, and more particularly, to a method of manufacturing a Vitrified tool having a long service life without causing a scratch on the surface of the workpiece during grinding, .

In general, the use of non-tapered diamond and boron nitride (CBN) tools is increasing year by year in high-speed grinding of super precision machine parts, electronic parts, optical parts, This is because the economy is guaranteed. For this reason, many tool makers have made a lot of effort and research in order to improve the grindability of the non-treaded tool.

Metal or resinoid diamond tools have been used in the past. In the process of manufacturing metal diamond tools, a certain amount of carbon particles are prepared, and the slurry of the workpiece pierces the carbon particles during the grinding operation The pore effect is obtained and the grinding property is improved. Also, the resinoid diamond tools are made by adding sodium sulfate and sodium chloride particles in a certain amount during the manufacturing process of the tool, so that the coolant dissolves the sodium sulfate or sodium chloride particles during the use, resulting in pores.

These improved metal or resinoid tools are superior to conventional tools in terms of grindability, but in terms of their grindability and economy, they do not reach the non-trivial tool.

In order to improve the porosity, each tool maker inserts particles such as wood powder, starch, animal bone, and hair at a certain ratio, and then sintering Since such pore additive is oxidized in the pore region, pores are formed in the pore portion, thereby improving the grinding performance in the grinding operation.

On the other hand, if you put too much of the system in place, it is difficult to mold itself and it is evaluated as a skill level for each company.

However, the above-mentioned non-tritide tool has higher porosity than the metal diamond tool or the resinoid diamond tool, and thus has excellent grinding performance. However, currently, there are various electronic parts such as quartz crystal, semiconductor wafer, In the case of a lapping machine, parts are not used.

Instead, the present working method is to grind garnet, alumina, GeC, SiC, etc., to select particles, to select the type and particle of the abrasive depending on the type of the workpiece, and to mix the abrasive particles with water, And lapping and mirror-surface work are performed while supplying to the mounted lapping machine. That is, in addition to performing the conventional method of taking out the abrasive slurry waste generated in the above process, pollution of the workplace, contamination of the workpiece and the defective product rate of 5-7%, the working time is also usually 30 minutes to 120 minutes It takes a long time.

The main reason for this is that scratching is caused on the surface of the workpiece when grinding with a non-tritide tool.

That is, in the conventional case, when a non-tritiated tool is manufactured, since animal bone, wood powder, starch, hair particles, and the like are added as a pore agent, it causes defective molding and defects in heat treatment process. Rise.

DISCLOSURE OF THE INVENTION In order to solve the above-mentioned problems, the present inventors have conducted extensive research and found that during the process of manufacturing diamonds, diamond particles are formed in a process of molding with a hydraulic press to form diamond like single crystals, We found that the portion of the diamond grains was stronger than the other side of the diamond grains, so that the diamond grains were consumed late and caused scratches. In other words, it has come to the conclusion that it is impossible to manufacture diamond particles by the conventional method of manufacturing the tool.

Therefore, the inventor of the present invention has developed a tool that does not attract diamond particles but has excellent grinding performance and does not generate scratches, that is, a tool that consumes less of the tool. The fact that these problems are common demands of not only the present invention but all related tool manufacturers And continue trial and error while continuing the study, leading to the present invention.

In short, an object of the present invention is to provide a method for producing a high-quality non-tritiated tool by forming pores of a tool by simply using water, without producing a defect rate at the time of molding.

Another object of the present invention is to enable the production of non-tritiated tools suitable for various applications by controlling the amount of water mentioned above.

In order to accomplish the above object, the present invention provides a method for preparing a slurry, comprising the steps of pulverizing glass particles and water to form a slurry, mixing the slurry obtained with diamond or CBN particles and carboxymethylcellulose (CMC) Drying the slurry in a vacuum freeze dryer; separating the slurry from the mold by rapidly freezing the slurry in the mold; heating the dried molded article in an electric furnace to keep it in a heated state, And sintering the resultant mixture.

The present invention also provides a method for producing a non-tritiated tool wherein the slurry in the milling process contains 8-35% water.

The present invention also provides a method for producing a non-tritiated tool which is performed while applying a pressure of 50-200 kg / m < 2 > with a quenching simultaneous hydraulic press.

The present invention also provides a method for producing a non-tritiated tool characterized in that a reducing atmosphere is maintained during the sintering process during the sintering process.

Hereinafter, a method for manufacturing a non-tie tool according to the present invention will be described in detail with reference to the accompanying drawings.

[Example 1]

[First Step]

The slurry was pulverized in a wet ball mill at a weight ratio of 80% of irregular glass particles (sand state) and 20% of water which were magnetized at 900 DEG C for 168 hours to obtain a pulverized slurry of 0.1 to 2 mu m.

[Second Step]

The slurry obtained in the first step is transferred into an elastic ball mill (using bourourethane). 78% of the slurry, 20% of the diamond particles and 2% of the CMC, and sufficiently mixed for 3 hours.

[Third Step]

The slurry containing the diamond obtained in the second step was filled in a container capable of applying vacuum and pressure to the sight window to about 70%, and then the valve attached to the top of the container was opened to remove the air bubbles in the slurry, The fine bubbles in the slurry are removed.

Then, the valve is closed, the vacuum pump is stopped, and the valve connected to the compressor is opened to apply air pressure of 6-15 kg / m 2 into the slurry container.

[Fourth Step]

A plate having a plurality of holes each having a diameter of 10 mm at intervals of 15 mm is installed on the upper and lower plates of the hydraulic press so that the freezing liquid flows through the upper and lower plates of the hydraulic press, And the refrigerated liquid is operated by the gear pump to flow the refrigerating liquid to the mold through the freezing tube and the refrigerating tube through the freezing tube of the lower plate. In this case, if the mold is small or thin, it is not necessary to make a hole through which the freezing liquid flows in the mold. The temperature of the mold is set at room temperature, and the mold is assembled to spray a small amount of freezing oil into the mold.

When the hydraulic press is operated and pressure is applied, the lid of the mold is covered and a tool-shaped space is left inside the mold. When the pressure of the hydraulic press is kept at 100-150 kg / m 2 and the temperature of the mold is kept at room temperature, a pipe installed at the lower end of the container in the third step and a 10 mm pipe valve connected to the mold space are opened, The air inside the mold instantly exits and the slurry is charged into the mold.

When the slurry valve is closed and ethylene glycol (EG) refrigerated at -65 ° C is frozen in the freezer, the gear pump is operated to circulate the freezing liquid through the freezing tube of the lower plate and the freezing tube of the mold to the freezer, The internal slurry is instantly frozen to -45 ° C.

Stop the freezing gear pump and operate the hydraulic press to separate the frozen tool mold from the mold and store in a -45 ° C freezer (this is to collect a certain amount).

[Step 5]

The molded article obtained in the fourth step is placed in a vacuum freeze dryer and freeze-dried while maintaining a high vacuum state for 24 hours. If the drying time is shortened, fine cracks (cracks) may occur, which may cause the tool to fail.

At this time, when the dried molded article is firstly inspected, it can be confirmed that fine pores are uniformly formed.

[Step 6]

The dried molding obtained in the fifth step was put into an electric furnace, and the temperature was raised at a rate of 2.3 ° C per minute, maintained at 550 ° C for 2 hours, increased again at a rate of 2.9 ° C per minute while nitrogen gas was introduced at 650 ° C, Then, turn off the power, keep the gas injection up to 650 ° C, lock the gas, and slowly cool to room temperature.

When the sintered product is taken out from the electric furnace and adhered to the iron shank after the temperature is reached to room temperature, a tool having diamond particles and pores having a very uniform pore size can be obtained. In other words, when a tool is used, a tool having no scratches is produced.

The method described above is suitable for grinding in the range of 800 to 20,000 mesh, and is economical and does not cause contamination when a product having a large quantity is applied.

[Example 2]

[First Step]

The slurry was pulverized in a wet ball mill at a weight ratio of irregular glass particles (sand state) of 72% and water of 28% magnetized at 900 DEG C for 168 hours to obtain a pulverized slurry of 0.1 to 2 mu m.

[Second Step]

The slurry obtained in the first step is transferred into an elastic ball mill and mixed with 78% of slurry, 20% of diamond particles and 2% of CMC for 2 hours at a weight ratio, and the slurry is taken out from the ball mill.

[Third Step]

When the mold is assembled and the mold lid is opened, the slurry obtained in the second step is charged into the mold, and the mold is put in the common position. When the vacuum pump is operated and the vacuum is maintained for 1-2 minutes, the bubbles in the slurry are removed.

[Fourth Step]

After stopping the vacuum pump, take out the mold from the common and put it on the hydraulic press, cover the mold lid, operate the hydraulic press and apply pressure of 50-100 kg / ㎡ to the lid of the mold. Is circulated through a gear pump at -50 ° C, the slurry inside the mold rapidly freezes.

[Step 5]

The gear pump for circulating refrigerant is stopped and the hydraulic press is operated to separate the tool molding from the mold. The mold is stored in a freezer at -30 ° C and a certain amount is collected and dried in a vacuum freeze dryer for 24 hours.

[Step 6]

The dried molded product was passed through a tunnel type electric furnace at a temperature of 900 ° C from room temperature up to 2.3 ° C per minute (7 hours required), maintained at 900 ° C for 1 hour, passed through slow cooling for 8 hours, do. The entire process of sintering maintains a reducing atmosphere.

When the sintered tool is bonded to the iron shank, the desired tool is produced.

The above method is easily applicable to the production of a tool having a simple shape or a small number of tools.

[Example 3]

[First Step]

The slurry was ground in a wet ball mill at a weight ratio of 65% of irregular glass particles (sand state) magnetized at 1250 ° C and 35% of water, and pulverized for 168 hours to obtain a pulverized slurry of 0.1-2 탆.

[Second Step]

The slurry obtained in the first step is transferred into an elastic ball mill and mixed with 78% slurry, 20% CBN particles and 2% CMC for 2 hours at a weight ratio, and the slurry is taken out from the ball mill.

[Third Step]

When the mold is assembled and the mold lid is opened, the slurry obtained in the second step is charged into the mold, and the mold is put in the common position. When the vacuum pump is operated and the vacuum is maintained for 1-2 minutes, the bubbles in the slurry are removed Vacuum may be held for 1-2 minutes while placed on a press).

[Fourth Step]

After stopping the vacuum pump, take out the mold from the common, put it on the hydraulic press, cover the mold lid, operate the hydraulic press, apply pressure of 150-200 kg / m 2 to the lid of the mold, Is circulated through a gear pump at -40 ° C, the slurry inside the mold rapidly freezes.

(Step 5)

The gear pump for circulating the freezing fluid is stopped and a hydraulic press is operated to separate the tool molding from the mold. The mold is stored in a freezer at -25 ° C and a certain amount is collected and dried in a vacuum freeze dryer for 24 hours.

[Step 6]

The dried molded product was placed in an electric furnace, and the temperature was increased from 2.0 ° C per minute to 2.0 ° C per minute while maintaining the oxidizing atmosphere at room temperature to 850 ° C. At 850 ° C, the temperature was increased by 2.9 ° C per minute while maintaining the reducing atmosphere. Keep cool while holding.

After reaching the normal temperature, the sintered product is taken out from the electric furnace and bonded to the iron shank to produce the desired tool.

[Example 4]

[First Step]

Irregular glass particles (sand state) magnetized at 1,230 DEG C are ground in a wet ball mill for 78 hours to obtain a slurry of 3 mu m or less.

The slurry is dried in a spray dryer.

[Second Step]

45% of the glass powder obtained in the first step and 45% of CBN were sufficiently mixed and then 2% of CMC was dissolved in 8% of water. Then, the mixture was added to the mixture and mixed. Then, the mixture was passed through a screen of 35 mesh, Particles are obtained.

[Third Step]

The mold is assembled with the temperature of the mold at room temperature, frozen oil is sprayed on the mold, and the mixed particles obtained in the second step are uniformly charged into the mold.

[Fourth Step]

The pressure of the hydraulic press was applied by operating the hydraulic press, and while the pressure of the hydraulic press was maintained at about 150-200 kg / m 2, the gear pump for the refrigeration fluid was operated to cool the EG refrigerated at -50 ° C, Is circulated into the tube through which the freezing liquid flows, the tool molding is rapidly cooled.

[Step 5]

The hydraulic press is operated to separate the tool moldings from the mold, store them in a freezer at -30 ° C, collect a certain amount, put them in a vacuum freeze dryer, and dry them for 24 hours.

[Step 6]

The dried molded article is put into an electric furnace and heated at a rate of 2.3 ° C per minute, and is maintained at 1,230 ° C for 1 hour while maintaining a reducing atmosphere at 700 ° C. Then, the power is turned off and slowly cooled while maintaining the reducing atmosphere.

After reaching the normal temperature, the molded product is taken out and bonded to the iron shank with an adhesive to complete the desired tool.

[Comparative Example 1]

The slurry obtained in the first step of Example 1 was placed in a container capable of applying vacuum and pressure, and designed and manufactured so that a freezing liquid would flow through the mold. The mold was fixed with bolts and the bubbles of the slurry in the cylinder were removed The valve installed in the ordinary end is opened, and the vacuum pump is operated to remove the air bubbles in the slurry.

This time, when the valve is closed and the compressor pressure valve is opened to open the valve connected to the mold at the lower end while maintaining the pressure in the cylinder at 6 kg / m 2, the slurry is instantaneously charged into the mold. When the gear pump is operated to circulate the -50 ° C polypropylene glycol (PG) solution through the freezing liquid pipe of the mold to the freezer, the slurry instantly freezes. The bolts are loosened and the frozen molded parts are separated and stored in a freezer at -30 ° C.

As a result of producing a finished product by collecting a certain amount of material and drying and sintering it in a vacuum freeze dryer, an additional operation of opening and locking the bolt was required, so that the productivity was somewhat lower than those of the above embodiments.

[Comparative Example 2]

The slurry containing the diamond was filled into the mold, the mold was fixed with a bolt, and the resultant was put in a freezer at -35 ° C for 1 hour, then the bolt was loosened and the frozen tool product was separated and dried by a freeze dryer to produce a tool by sintering in an electric furnace As a result, productivity was also somewhat low.

In the above-described various embodiments, the reason for quick-freezing while applying pressure to the lid of a mold using a hydraulic press or under pressure is that the water is frozen and expanded, , And the pressure applied to the hydraulic press may vary depending on the size of the mold.

The present invention is a method for solving problems such as cracking and cracking, diamond particles and irregular pores generated in the process of manufacturing non-tritiated tools by a simple method, and can supply excellent tools at low cost It is a useful invention.

Thus, the present invention is expected not only to raise the level of the technology in the manufacturing industry of the tool, but also to contribute to the ultra-precision processing industry by suggesting the direction and possibility of unlimited technology development in future.

While the invention has been described in connection with what is presently considered to be practical and exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, .

Claims (5)

Comprising the steps of: milling glass particles and water to form a slurry; mixing the slurry with diamond or CBN particles and CMC; filling the mixture obtained in the mixing step into a mold; And sintering the molded article by heating in an electric furnace, maintaining the heated state, and then slowly cooling the molded article to room temperature to obtain a sintered product, A method of manufacturing a tool. The method of claim 1, wherein the slurry in the step of forming the slurry is formed to contain 8 to 35% by weight of water. The method of manufacturing a non-tritide tool according to claim 1, wherein in the forming step, pressure is applied by a quenching simultaneous hydraulic press. 4. The method of claim 3, wherein the pressure of the hydraulic press is 50-200 kg / m < 2 >. The method for producing a non-tritide tool according to claim 1, wherein a reducing atmosphere is maintained during the entire sintering step in the sintering step.