TWI782854B - Non-sintered or low-temperature-sintered grinding wheel and preparation method thereof - Google Patents

Abstract

The present invention provides a non-sintered or low-temperature-sintered grinding wheel and a preparation method thereof. The preparation method comprises: step (a): mixing a mullite powder, a calcined kaolin, an abrasive and a liquid binder to obtain a slurry; wherein, the liquid binder comprises an alkaline solution or a colloidal silica solution; and step (b): sequentially subjecting the slurry to a prepressing step and a shaping step to obtain the non-sintered or low-temperature-sintered grinding wheel; the shaping step comprises standing at room temperature or sintering at 350℃ to 700℃. Accordingly, the preparation method has effects of low energy consumption and low cost.

Description

Non-sintered or low-temperature sintered grinding wheel and its preparation method

The invention relates to a grinding wheel and its preparation method, especially to a non-sintered or low-temperature sintered grinding wheel and its preparation method.

Grinding wheel is a common grinding tool. Its structure is mainly composed of abrasives, bonding agents and pores. Among them, abrasives are usually the main body in the structure of the grinding wheel and endow the grinding wheel with functions such as grinding, cutting and polishing; the role of the bonding agent is to bond Abrasive particles to form a grinding wheel with a fixed shape and structure; while pores are the remaining part of the grinding wheel structure except for the abrasive and the bond, which mainly makes the gap between the abrasive and the bond, which can provide removal of wear debris and cooling, etc. effect.

Because the grinding, cutting and polishing of the grinding wheel are all achieved by cutting and grinding the surface of the object continuously with countless abrasive particles protruding from the surface of the grinding wheel during the high-speed rotation process. Therefore, in order to achieve different purposes and needs, or according to the material of different objects, in addition to selecting suitable materials and types of abrasives, the abrasive particles in the grinding wheel also need to have appropriate bonding strength, and the type of bonding agent and grinding wheel The manufacturing process is an important factor that will affect the bonding strength.

Generally speaking, grinding wheels can be divided into ceramic grinding wheels, resin grinding wheels, metal grinding wheels, etc. according to the type of binder selected. Among them, ceramic grinding wheels have good heat resistance, small thermal deformation, good chemical resistance and large porosity. And many other advantages, therefore, ceramic grinding wheels are usually selected when grinding objects.

However, in the general ceramic grinding wheel manufacturing process, after uniform mixing of abrasive grains and ceramic powder as a binder and preliminary compression molding, a sintering step with a temperature higher than 1000°C is required, and the high-temperature sintering time is usually as long as 7 days , not only consumes a lot of energy, but also increases the production cost; in addition, in the process of high-temperature sintering, it is still necessary to pay attention to the changes of the grinding wheel and adjust the sintering conditions accordingly, otherwise the prepared grinding wheel may have defects that the processing performance is not as expected. Or it may even be deformed, cracked and damaged.

Therefore, there is still a need to find and develop new technical solutions that can produce applicable grinding wheels without high-temperature sintering or even sintering, so as to avoid high-temperature energy consumption and reduce production costs.

In view of the existing defects in the prior art, the purpose of the present invention is to provide a method for making a grinding wheel, which can produce an applicable grinding wheel at a lower sintering temperature or even without sintering in the manufacturing process of the grinding wheel. In order to achieve the effect of reducing energy consumption and cost at the same time.

In order to achieve the aforementioned object, the present invention provides a method for preparing a non-sintered or low-temperature sintered grinding wheel, which comprises the following steps: step (a): mixing a mullite powder, a calcined kaolin, an abrasive and a a liquid binder to obtain a slurry; wherein the liquid binder includes an alkaline solution or a silica gel solution; and step (b): making the slurry undergo a pre-pressing step and a molding step in sequence, The non-sintered or low-temperature sintered grinding wheel is obtained; wherein, the molding step includes static molding or sintering under the condition of 350°C to 700°C.

By selecting a specific composition and a specific type of liquid binder as the raw material of the grinding wheel, it can be formed by standing after pre-pressing without sintering, or sintering at a sintering temperature significantly lower than that of the prior art, that is Grinding wheels suitable for subsequent grinding processes can be produced. Accordingly, the manufacturing method of the present invention has the effect of reducing energy consumption and cost of the grinding wheel manufacturing process.

According to the present invention, the mullite powder is a mineral mainly composed of aluminosilicate, and its chemical formula can be expressed as 3Al ₂ O ₃ ∙ 2SiO ₂ or 2Al ₂ O ₃ ∙SiO ₂ .

According to the present invention, the calcined kaolin-based kaolin is obtained by high-temperature calcination (about 500° C. to 1700° C.), and the high temperature mainly destroys the OH bond of the layered kaolin to increase its activity.

According to the present invention, the colloidal silica solution includes silicon dioxide and water. Specifically, the silicic acid colloidal solution refers to a hydrosol solution mainly composed of silicon dioxide particles, and can be obtained by removing cations in a silicate solution by ion exchange, such as but not Limited to alkali metal cations, such as sodium and potassium ions. Preferably, based on the total weight of the silicic acid colloid solution, the content of silicon dioxide is greater than or equal to 20 weight percent (weight percent, wt%) and less than or equal to 30 wt%. More preferably, based on the total weight of the silicic acid colloid solution, the content of the silicon dioxide is greater than or equal to 28 wt% and less than or equal to 30 wt%.

According to the present invention, the silicate solution includes a silicate colloid and water, and the silicate colloid includes silicon dioxide and alkali metal oxides. Specifically, the alkali metal oxide comprises sodium oxide, potassium oxide or a combination thereof, that is, the silicate colloid comprises silicon dioxide and sodium oxide; the silicate colloid comprises silicon dioxide and potassium oxide; or The silicate colloid includes silicon dioxide, sodium oxide and potassium oxide. Preferably, the alkali metal oxide is sodium oxide, that is, the silicate colloid includes silicon dioxide and sodium oxide. Preferably, based on the total weight of the silicate solution, the content of the silicon dioxide is greater than or equal to 20 wt% and less than or equal to 30 wt%, and the content of the alkali metal oxide is greater than or equal to 9 wt% and less than or equal to 10 wt%. More preferably, based on the total weight of the silicate solution, the content of silicon dioxide is greater than or equal to 28 wt% and less than or equal to 30 wt%.

Preferably, the amount of the abrasive is 100 parts by weight, the amount of the mullite powder is 10 parts by weight to 20 parts by weight, the amount of the calcined kaolin is 2 parts by weight to 8 parts by weight, and the amount of the liquid binder is 8 parts by weight to 20 parts by weight.

In some embodiments of the present invention, the silicate solution is a sodium silicate solution, and the sodium silicate solution includes sodium silicate and water, and based on the total weight of the sodium silicate solution, the silicic acid The sodium content is greater than or equal to 10 wt% and less than or equal to 45 wt%. In other embodiments of the present invention, the content of the sodium silicate is greater than or equal to 10 wt% and less than or equal to 40 wt%. In other embodiments of the present invention, the content of the sodium silicate is greater than or equal to 10 wt% and less than or equal to 20 wt%. In other embodiments of the present invention, the content of the sodium silicate is greater than or equal to 30 wt% and less than or equal to 45 wt%. In other embodiments of the present invention, the content of the sodium silicate is greater than or equal to 37 wt% and less than or equal to 40 wt%.

In some embodiments of the present invention, the silicate solution is a potassium silicate solution, and the potassium silicate solution includes potassium silicate and water, and based on the total weight of the potassium silicate solution, the silicic acid The content of potassium is greater than or equal to 10 wt% and less than or equal to 45 wt%. In other embodiments of the present invention, the potassium silicate content is greater than or equal to 10 wt% and less than or equal to 40 wt%. In other embodiments of the present invention, the potassium silicate content is greater than or equal to 10 wt% and less than or equal to 20 wt%. In other embodiments of the present invention, the potassium silicate content is greater than or equal to 25 wt% and less than or equal to 45 wt%. In other embodiments of the present invention, the potassium silicate content is greater than or equal to 29 wt% and less than or equal to 40 wt%.

In some embodiments of the present invention, the silicate solution is a mixed solution of sodium silicate solution and potassium silicate solution, and the mixed solution includes sodium silicate, potassium silicate and water, and the mixed solution Based on the total weight, the content of the sum of sodium silicate and potassium silicate is greater than or equal to 10 wt% and less than or equal to 65 wt%. In other embodiments of the present invention, the content of the sum of sodium silicate and potassium silicate is greater than or equal to 10 wt% and less than or equal to 40 wt%. In other embodiments of the present invention, the content of the sum of sodium silicate and potassium silicate is greater than or equal to 10 wt% and less than or equal to 20 wt%. In other embodiments of the present invention, the content of the sum of sodium silicate and potassium silicate is greater than or equal to 35 wt% and less than or equal to 65 wt%. In other embodiments of the present invention, the content of the sum of sodium silicate and potassium silicate is greater than or equal to 30 wt% and less than or equal to 40 wt%.

Preferably, the alkaline solution includes a sodium-based alkaline solution, a potassium-based alkaline solution or a sodium-based potassium-based mixed alkaline solution; the sodium-based alkaline solution contains 10 wt% to 40 wt% of Sodium silicate, the potassium-based alkaline solution contains potassium silicate with a content of 10 wt% to 40 wt%, the sodium-based potassium mixed alkaline solution contains sodium silicate with a total content of 10 wt% to 40 wt% and potassium silicate.

Preferably, the solid-to-liquid ratio of the slurry is 100:7 to 100:17. More preferably, the solid-to-liquid ratio of the slurry is 100:7 to 100:15. It should be understood that the solid-to-liquid ratio of the slurry is calculated by taking the total weight of the mullite powder, calcined kaolin and abrasive contained therein as the total weight of the solid, and taking the weight of the liquid binder as the total weight of the liquid. For example, if the solid-to-liquid ratio of the slurry is 100:7, it means that the total weight of the mullite powder, calcined kaolin and abrasive contained in the slurry is taken as 100 parts by weight, and the liquid binder contained in the slurry Then it is 7 parts by weight.

According to the present invention, the abrasive generally refers to a plurality of granular objects with edges and corners and a certain hardness, and usually a suitable type of abrasive is selected according to different needs and purposes. For example, if the object to be ground contains iron metal, alumina-based abrasives are usually selected; and if the object to be ground does not contain iron metal, silicon carbide-based abrasives are usually selected. Specifically, the abrasive can be diamond, diamond, aluminum oxide, silicon carbide, boron nitride or a combination thereof, but is not limited thereto. Preferably, the abrasive includes alumina, silicon carbide, aluminum nitride or a combination thereof.

Preferably, the molding step is static molding, and the static molding condition is at room temperature (about 30° C. to 35° C.) for more than 3 days. More preferably, the molding step is static molding, and the static molding condition is at room temperature (about 30° C. to 35° C.) for 3 days to 7 days. For example, the static forming can be steam curing at room temperature (about 30° C. to 35° C.) for 3 days to 7 days, but it is not limited thereto.

According to the present invention, when the molding step is selected to be sintered at a temperature of 350° C. to 700° C., the sintering time is 3 hours to 24 hours. Preferably, the time for sintering is 3 hours to 5 hours.

According to the present invention, the pre-pressing step includes the step of injecting the slurry into a mold under a specific pressure and pressing it into shape. Preferably, the pre-pressing step is to press the slurry under the condition of a pressure of 80 kilogram force per square centimeter (kgf/cm ² ) to 250 kgf/cm ² . More preferably, the pre-pressing step is to press the slurry under the condition of a pressure of 100 kgf/cm ² to 250 kgf/cm ² .

According to the present invention, the slurry may be subjected to a drying step after the pre-pressing step and before the forming step. For example, the drying step may be drying the slurry at a temperature of 50° C. to 120° C. for 20 hours to 30 hours, but is not limited thereto.

According to the present invention, the step (a) further comprises the following steps: step (a1): mixing the mullite powder, the calcined kaolin and the abrasive to obtain a mixture; and step (a2): mixing the mixture with the liquid binder to obtain the slurry.

In some embodiments of the present invention, the liquid binder can be the alkaline solution or the silica gel solution, and the forming step is static forming. In other embodiments of the present invention, the liquid binder is the alkaline solution, and the forming step is sintering at a temperature of 350°C to 700°C.

In addition, the present invention also provides a non-sintered or low-temperature sintered grinding wheel, which includes an abrasive, a bonding material and a plurality of pores, the bonding material is bonded to the abrasive, and the pores are scattered and formed in the bonding material, and the bonding material and Among the abrasive materials, the bonding material is made by mixing and solidifying a mullite powder, a calcined kaolin and a liquid bonding agent; the liquid bonding agent includes an alkaline solution or a silica gel solution.

Preferably, the amount of the abrasive is 100 parts by weight, the amount of the mullite powder is 10 parts by weight to 20 parts by weight, the amount of the calcined kaolin is 2 parts by weight to 8 parts by weight, and the amount of the liquid binder is 8 parts by weight to 20 parts by weight.

Preferably, the grinding wheel is produced by the aforementioned method of the present invention.

Preferably, the porosity of the grinding wheel is greater than or equal to 20 volume percent (vol%) and less than or equal to 65 vol%, and the flexural strength of the grinding wheel is greater than or equal to 10 million Pa (MPa) and less than Or equal to 70 MPa, the water absorption of the grinding wheel is greater than or equal to 10% and less than or equal to 25%.

In this specification, the range represented by "small value to large value" means that the range is greater than or equal to the small value and less than or equal to the large value unless otherwise specified. For example: sintering under the condition of 350°C to 700°C means that the range of sintering temperature is "greater than or equal to 350°C and less than or equal to 700°C".

Several examples are listed below as examples to illustrate the implementation of the present invention. Those skilled in the art can easily understand the advantages and effects that the present invention can achieve through the contents of this specification, and perform various operations without departing from the spirit of the present invention. Modifications and changes to implement or apply the content of the present invention.

Example 1 : Non-sintered grinding wheel

According to the composition ratio listed in Table 1 below, appropriate amount of mullite powder, calcined kaolin and alumina (as abrasive) were weighed and uniformly stirred and mixed to obtain a mixture. Then, after adding an appropriate amount of silicic acid colloidal solution into the mixture, it is uniformly stirred and mixed to obtain a slurry, and the solid-to-liquid ratio of the mixture and the silicic acid colloidal solution in the slurry is about 100:14.92.

Subsequently, the slurry was pressed into a mold with a pressure of 200 kgf/cm ² and a pre-pressing step was performed, and then the mold containing the slurry was dried at a temperature of 60°C for 24 hours , and finally left it to room temperature to obtain the non-sintered grinding wheel of Example 1.

Example 2 : Non-sintered grinding wheel

According to the composition ratio listed in Table 1 below, appropriate amount of mullite powder, calcined kaolin and alumina (as abrasive) were weighed and uniformly stirred and mixed to obtain a mixture. Then, after adding an appropriate amount of alkaline solution into the mixture, it is uniformly stirred and mixed to obtain a slurry, and the solid-to-liquid ratio of the mixture to the alkaline solution in the slurry is about 100:14.43.

Subsequently, the slurry was pressed into a mold with a pressure of 100 kgf/cm ² and a pre-pressing step was performed, and then the mold containing the slurry was dried at a temperature of 60°C for 24 hours , and finally left it to room temperature to obtain the non-sintered grinding wheel of Example 2.

Example 3 : Non-sintered grinding wheel

According to the composition ratio listed in Table 1 below, appropriate amount of mullite powder, calcined kaolin and alumina (as abrasive) were weighed and uniformly stirred and mixed to obtain a mixture. Then, after adding an appropriate amount of silicic acid colloidal solution into the mixture, the mixture was uniformly stirred to obtain a slurry, and the solid-to-liquid ratio of the mixture and the silicic acid colloidal solution in the slurry was about 100:8.06.

Subsequently, the slurry was pressed into a mold with a pressure of 250 kgf/cm ² and a pre-pressing step was performed, and then the mold containing the slurry was dried at a temperature of 100°C for 24 hours , and finally left it to room temperature to obtain the non-sintered grinding wheel of Example 3.

Example 4 : Low temperature sintered grinding wheel

According to the composition ratio listed in Table 1 below, appropriate amount of mullite powder, calcined kaolin and alumina (as abrasive) were weighed and uniformly stirred and mixed to obtain a mixture. Then, after adding an appropriate amount of alkaline solution into the mixture, it is uniformly stirred and mixed to obtain a slurry, and the solid-to-liquid ratio of the mixture to the alkaline solution in the slurry is about 100:14.43.

Subsequently, the slurry was pressed into a mold with a pressure of 150 kgf/cm ² and a pre-pressing step was performed, and then the mold containing the slurry was sintered at a temperature of 700° C. for 5 hours, Finally, it was left to stand at room temperature, and the low-temperature sintered grinding wheel of Example 4 was obtained. Table 1: Components of the non-sintered grinding wheel of Examples 1 to 3 and the low-temperature sintered grinding wheel of Example 4, the amount of each component (taking the amount of abrasive as 100 parts by weight) and molding conditions. group Grinding wheel composition Molding conditions Abrasive (parts by weight) Mullite powder (parts by weight) Calcined kaolin (parts by weight) liquid binder Dosage (parts by weight) type Example 1 100 13.3 3.3 17.4 silica gel solution Stand at room temperature Example 2 100 12 3 12 alkaline solution Stand at room temperature Example 3 100 18 6 10 silica gel solution Stand at room temperature Example 4 100 20 6 15 alkaline solution Sintering at 700°C

Test case 1 : Physical characteristic test of grinding wheel

In this test example, the non-sintered grinding wheel of Examples 1 to 3 and the low-temperature sintered grinding wheel of Example 4 are used to test the physical properties of the grinding wheel, and the test items include rotation test, porosity measurement, flexural strength measurement and water absorption measurement.

The rotary test system is tested with a rotary testing machine; the porosity is measured with the Archimedes drainage method; the flexural strength is measured with the three-point bending method; and the water absorption is measured with the ASTM C209 -98 test procedure (water absorption test) for determination. The test results of the physical properties of the non-sintered grinding wheel of Examples 1 to 3 and the low-temperature sintered grinding wheel of Example 4 are listed in Table 2 below. Table 2: Physical property test results of the non-sintered grinding wheel of Examples 1 to 3 and the low-temperature sintered grinding wheel of Example 4. group Rotation test results of the maximum speed (m/s) Porosity (vol%) Flexural strength (MPa) Water absorption (%) Example 1 33 25 twenty one 15 Example 2 40 35 38 10 Example 3 50 43 10 17 Example 4 20 twenty three 15 18

From the results in Table 2 above, it can be seen that if the standard specifications of general grinding wheels are usually about 20 vol%, the flexural strength is about 10 MPa to 70 MPa, and the water absorption is about 10% to 25%. The non-sintered grinding wheels of 1 to 3 and the low-temperature sintered grinding wheel of Example 4 all have the characteristics of meeting the standard specifications of grinding wheels, so they can be applied to the subsequent grinding process. In addition, the non-sintered grinding wheel of Examples 1 to 3 and the low-temperature sintered grinding wheel of Example 4 all have a porosity higher than that of ordinary grinding wheels, indicating that they have better removal of grinding debris and cooling effects. It can be seen that the non-sintered grinding wheel of Examples 1 to 3 and the low-temperature sintered grinding wheel of Example 4 not only meet the standard specifications of general grinding wheels, but also have better porosity and can be applied to grinding processes.

To sum up, the preparation method of the present invention can be sintered without sintering, or sintering at a sintering temperature significantly lower than that of the prior art by selecting a specific proportion of components and a specific type of liquid binder as the raw material of the grinding wheel, that is, Grinding wheels suitable for subsequent grinding applications can be obtained. Accordingly, the present invention provides the industry with a grinding wheel manufacturing method with low energy consumption and low cost, and has great development potential and commercial value.

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Claims (10)

A method for preparing a non-sintered or low-temperature sintered grinding wheel, comprising the following steps: step (a): mixing a mullite powder, a calcined kaolin, an abrasive and a liquid binder to obtain a slurry; wherein the liquid binder Contains an alkaline solution or a silicic acid colloid solution, and the amount of the abrasive is 100 parts by weight, the amount of the mullite powder is 10 parts by weight to 20 parts by weight, and the amount of the calcined kaolin is 2 parts by weight to 8 parts by weight part, the amount of the liquid binder is 8 parts by weight to 20 parts by weight; and step (b): making the slurry undergo a pre-pressing step and a molding step in order to obtain the non-sintered or low-temperature sintered grinding wheel; wherein , the molding step includes static molding or sintering under the condition of 350°C to 700°C. The method according to claim 1, wherein the silicic acid colloid solution includes silicon dioxide and water. The method according to claim 2, wherein, based on the total weight of the silicic acid colloid solution, the content of silicon dioxide is greater than or equal to 20% by weight and less than or equal to 30% by weight. The preparation method as described in Claim 1, wherein the alkaline solution comprises a sodium-based alkaline solution, a potassium-based alkaline solution or a sodium-based potassium-based mixed alkaline solution; the sodium-based alkaline solution contains 10 Weight percent to 40 weight percent sodium silicate, the potassium-based alkaline solution contains potassium silicate with a content of 10 weight percent to 40 weight percent, and the sodium-based potassium-based mixed alkaline solution contains a total content of 10 weight percent to 40 Sodium silicate and potassium silicate in weight percent. The method according to claim 1, wherein the slurry has a solid-to-liquid ratio of 100:7 to 100:17. The method according to any one of claims 1 to 5, wherein the abrasive comprises alumina, silicon carbide, aluminum nitride or a combination thereof. The method according to any one of claims 1 to 5, wherein the molding step is static molding, and the static molding condition is at room temperature for more than 3 days. A non-sintered or low-temperature sintered grinding wheel, which includes an abrasive, a bonding material and a plurality of pores, the bonding material binds the abrasive, and the pores are scattered in the bonding material and between the bonding material and the abrasive, wherein , the bonding material is prepared by mixing and solidifying a mullite powder, a calcined kaolin and a liquid bonding agent; the liquid bonding agent includes an alkaline solution or a silica gel solution; wherein the amount of the abrasive is used as For 100 parts by weight, the mullite powder is used in an amount of 10 to 20 parts by weight, the calcined kaolin is used in an amount of 2 to 8 parts by weight, and the liquid binder is used in an amount of 8 to 20 parts by weight. The grinding wheel as described in claim 8, wherein the grinding wheel is produced by the method as described in any one of claims 1 to 7. The grinding wheel as described in claim 8 or 9, wherein the porosity of the grinding wheel is greater than or equal to 20 volume percent and less than or equal to 65 volume percent, and the flexural strength of the grinding wheel is greater than or equal to 10 million Pa and less than or equal to Equal to 70 million Pa, the water absorption of the grinding wheel is greater than or equal to 10% and less than or equal to 25%.