Preparation method of super-soft and large-pored ceramic grinding wheel

Abstract

The application provides a preparation method of an ultra-soft and large-pored ceramic grinding wheel, and aims at solving the problem that a traditional grinding wheel is easy to cause burn and scratch on the surface of a high-hardness roller such as a high-chromium steel roller or a high-speed steel roller; the ceramic grinding wheel is composed of a working layer and a non-working layer; the materials in the working layer are weighed according to percentage by weight, wherein the abrasive is 80%, the binder is 9%, the wetting agent is 1.5%, and the organic composite pore-forming agent is 9.5%; the materials in the non-working layer are weighed, wherein the ordinary corundum abrasive is 81%, the binder is 11%, the wetting agent is 1.5%, and the organic composite pore-forming agent is 6.5%; the grinding wheel is divided into the working layer and the non-working layer, the ordinary corundum abrasive and the ceramic corundum abrasive are combined in the working layer, the cost is controlled, the characteristics of the ceramic corundum, i.e., good self-sharpening, small abrasive grains and sharp cutting edges of each grain, are utilized, and the surface precision of the high-chromium steel roller or the high-speed steel roller is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ceramic grinding wheel, in particular to a preparation method of super-soft large-pore ceramic grinding wheel. BACKGROUND

[0002] The grinding precision and surface quality of the roll mainly depend on the matched grinding wheel selected for the roll, in addition to the precision of the roll grinder. With the increasing precision requirement of the cold-rolled roll grinding process, the material of the cold-rolled roll is replaced from the traditional 9Cr2Mo to high-chromium steel or high-speed steel. The high-chromium steel or high-speed steel cold-rolled roll adds Mo (molybdenum), V (vanadium), W (tungsten) and other strong carbide forming elements, which greatly improve the hardness and wear resistance of the cold-rolled roll after forming carbide with C.

[0003] However, the existing grinding wheel has the following problems when processing high-chromium steel or high-speed steel cold-rolled roll:

[0004] 1. When the traditional grinding wheel processes the roll surface, the higher hardness of the roll surface requires higher speed and longer time for the grinding wheel to process, which causes local thermal stress concentration of the grinding wheel, resulting in burn of the roll surface.

[0005] 2. When the traditional grinding wheel processes the roll, the grinding material of the grinding surface of the grinding wheel will be blocked, causing scratches on the roll surface.

[0006] 3. When the super-soft hardness grinding wheel is used to process the roll, the green strength of the formed roll is low, and the super-soft hardness ceramic grinding wheel cannot be prepared due to the difficulty in clamping. SUMMARY

[0007] In view of the above problems, the present application provides a preparation method of super-soft large-pore ceramic grinding wheel to solve the problem that the traditional grinding wheel is easy to cause burn and scratches on the roll surface when processing high-chromium steel, high-speed steel and other high-hardness rolls.

[0008] To achieve the above purpose, the technical scheme of the present application is as follows:

[0009] The super-soft large-pore ceramic grinding wheel is composed of a working layer and a non-working layer. The working layer is composed of 80% of abrasive, 9% of binder, 1.5% of wetting agent and 9.5% of organic composite pore-forming agent.

[0010] The non-working layer is composed of 81% of ordinary corundum abrasive, 11% of binder, 1.5% of wetting agent and 6.5% of organic composite pore-forming agent.

[0011] The abrasive grains in the working layer are 70-95%, wherein 50%-70% of common corundum abrasive grains and 30-50% of ceramic corundum abrasive grains are included respectively;

[0012] The organic composite pore-forming agent is composed of refined naphthalene, dextrin powder and spherical pitch.

[0013] The preparation method of the grinding wheel comprises the following steps:

[0014] (1) mixing, in the working layer manufacturing, firstly, the ceramic corundum abrasive grains and the common corundum abrasive grains are respectively poured into the counter-current mixing pot, and stirred for 3 min, then the wetting agent is added, and stirred for 3 min, then the binder is added, and stirred for 5 min, and finally the organic composite pore-forming agent is added, and stirred for 5 min;

[0015] In the non-working layer manufacturing, firstly, the common corundum abrasive grains are poured into the counter-current mixing pot and stirred for 3 min, then the wetting agent is added, and stirred for 3 min, then the binder is added, and stirred for 5 min, and finally the organic composite pore-forming agent is added, and stirred for 5 min;

[0016] (2) forming, firstly, the mixed raw materials in the step (1) are weighed according to the requirements of the working layer and the non-working layer, and then are pressed into the grinding wheel blank on the grinding wheel forming machine group at 7.5Mpa in two times, the first time is 1 / 3 of the total pressure, and the second time is pressed at the total pressure, and the pressure is maintained for 1 min;

[0017] (3) trimming, the concave-convex part on the upper end of the grinding wheel blank in the step (2) is removed, and the size is trimmed;

[0018] (4) drying, the grinding wheel blank trimmed in the step (3) is placed in the kiln and heated to 110 DEG C for drying, and after drying for 36h, the grinding wheel blank is naturally cooled to room temperature;

[0019] (5) sintering, the grinding wheel blank dried in the step (4) is placed in the kiln at 900 DEG C, and sintered for 8h, and the grinding wheel finished product is obtained.

[0020] Compared with the prior art, the technical scheme provided by the application has the following advantages:

[0021] 1. By dividing the grinding wheel into the working layer and the non-working layer, the common corundum abrasive grains and the ceramic corundum abrasive grains are combined in the working layer, the cost is controlled, the characteristics of the ceramic corundum, i.e. good self-sharpening and small abrasive grain, are utilized, and each grain is a sharp cutting edge, so that the surface precision of the high-chromium steel roller or the high-speed steel roller is ensured.

[0022] 2. By introducing an organic composite pore-forming agent, which melts at 110℃ during the drying process of the grinding wheel, a cementing effect is generated, greatly improving the strength of the blank. Spherical asphalt is added to the organic composite pore-forming agent. Taking advantage of the high fixed carbon content and low ash content of the spherical asphalt, the carbonization degree and adhesion of the organic composite pore-forming agent are enhanced. At a temperature of 550-600℃, after the organic composite pore-forming agent undergoes a carbonization-oxidation reaction, the in-situ voids and through-holes overlap, which not only increases the porosity of the grinding wheel, but also makes the pore distribution more uniform. During grinding, the heat dissipation of the grinding wheel is accelerated, and local concentration of thermal stress is prevented, thereby avoiding the grinding wheel burning the workpiece.

[0023] 3. By adding ceramic corundum abrasive, the small grain size of ceramic corundum abrasive causes intergranular fracture under the grinding force after the abrasive grains wear down. The detached grains are fine grains, which are microscopic damage. The amount of abrasive lost is small, thereby increasing the service life of the grinding wheel. Detailed Implementation

[0024] The specific embodiments of the present invention will be described in further detail below.

[0025] In the following embodiments:

[0026] The binder consists of: 20% borosilicate glass, 40% clay, 20% feldspar, and 10% lithium salt.

[0027] Example 1:

[0028] Weigh the materials in the working layer (ultra-soft layer) by weight percentage: 80% abrasive (50% ordinary corundum abrasive, 50% ceramic corundum abrasive), 9% binder, 1.5% wetting agent, and 9.5% organic composite pore-forming agent (60% refined naphthalene, 30% dextrin powder, and 10% spherical pitch).

[0029] Weigh the materials in the non-working layer (slightly hard layer): 81% ordinary corundum abrasive, 11% binder, 1.5% wetting agent, and 6.5% organic composite pore-forming agent (60% refined naphthalene, 30% dextrin powder, and 10% spherical pitch).

[0030] First, the abrasive, wetting agent, binder, and organic composite pore-forming agent are mixed in the above proportions. The mixed material is placed in a molding die and then pressed twice at 7.5 MPa on a hydraulic press. The first pressing is 1 / 3 of the total pressure, and the second pressing is the total pressure, held for 1 minute to obtain a grinding wheel blank. After pressing and shaping, the uneven parts at the top of the grinding wheel blank are removed. Next, the dressed grinding wheel blank is placed in a kiln at 110℃ for drying. After drying for 36 hours, it is naturally cooled to room temperature. Finally, the dried grinding wheel blank is placed in a kiln at 900℃ and fired for 8 hours. After naturally cooling to room temperature, the finished grinding wheel part is obtained.

[0031] Example 2:

[0032] Take the materials in the working layer (ultra-soft layer) by weight percentage: abrasive 80% (ordinary corundum abrasive 67%, ceramic corundum abrasive 33%), binder 9%, wetting agent 1.5%, organic composite pore-forming agent 9.5% (pure naphthalene 75%, dextrin powder 19%, spherical pitch 6%);

[0033] Take the materials in the non-working layer (slightly hard layer): ordinary corundum abrasive 81%, binder 11%, wetting agent 1.5%, organic composite pore-forming agent 6.5% (pure naphthalene 75%, dextrin powder 19%, spherical pitch 6%);

[0034] The manufacturing steps are consistent with those in Example 1.

[0035] The difference between Example 2 and Example 1 is that the proportion of ordinary corundum abrasive and ceramic corundum abrasive in the working layer abrasive changes, and the proportion of spherical pitch in the organic composite pore-forming agent decreases, and the pure naphthalene and dextrin powder are added in equal proportion according to the total mass to maintain the same percentage of organic composite pore-forming agent content.

[0036] Example 3:

[0037] Take the materials in the working layer (ultra-soft layer) by weight percentage: abrasive 80% (ordinary corundum abrasive 100%), binder 9%, wetting agent 1.5%, organic composite pore-forming agent 9.5% (pure naphthalene 60%: dextrin powder 30%: spherical pitch 10%);

[0038] Take the materials in the non-working layer (slightly hard layer): ordinary corundum abrasive 81%, binder 11%, wetting agent 1.5%, organic composite pore-forming agent 6.5% (pure naphthalene 80%: dextrin powder 15%: spherical pitch 5%);

[0039] The manufacturing steps are consistent with those in Example 1.

[0040] The difference between Example 3 and Example 1 is that the ceramic corundum abrasive is not added in the working layer abrasive.

[0041] Example 4:

[0042] Take the materials in the working layer (ultra-soft layer) by weight percentage: abrasive 80% (ordinary corundum abrasive 50%, ceramic corundum abrasive 50%), binder 9%, wetting agent 1.5%, organic composite pore-forming agent 9.5% (pure naphthalene 80%, dextrin powder 20%);

[0043] Take the materials in the non-working layer (slightly hard layer): ordinary corundum abrasive 81%, binder 11%, wetting agent 1.5%, organic composite pore-forming agent 6.5% (pure naphthalene 80%, dextrin powder 20%);

[0044] The manufacturing steps are consistent with those in Example 1.

[0045] Example 4 differs from Example 1 in that the addition of spherical pitch in the organic composite pore-forming agent is cancelled, and the fine naphthalene and dextrin powder are added in equal proportions according to the total mass to maintain the same content percentage in the organic composite pore-forming agent.

[0046] Example 5:

[0047] The materials in the working layer (ultra-soft layer) are weighed in percentage by weight: 90% of abrasive (50% of ordinary corundum abrasive and 50% of ceramic corundum abrasive), 7.5% of binder, and 2.5% of wetting agent;

[0048] The materials in the non-working layer (slightly hard layer) are weighed: 88% of ordinary corundum abrasive, 9.5% of binder, and 2.5% of wetting agent.

[0049] The abrasive, wetting agent, and binder are mixed in the above proportions, and the mixed materials are placed in a molding mold. Then, they are pressed twice on an oil press at 7.5 MPa, with the first pressing being 1 / 3 of the total pressure, and the second pressing being at the total pressure, maintaining for 1 min. After pressing and molding, the concave-convex part at the upper end of the grinding wheel blank is removed, and finally the grinding wheel blank is placed in an electric furnace at 900°C for 8h, and then naturally cooled to room temperature to obtain the grinding wheel piece.

[0050] Example 5 differs from Example 1 in that the addition of organic composite pore-forming agent in the working layer and non-working layer is cancelled, and the abrasive, binder, and wetting agent are added or reduced in equal proportions according to the total mass to maintain the same content percentage.

[0051] In Comparative Example 1, there is no distinction between the working layer and the non-working layer, and the addition of ceramic corundum abrasive and organic composite pore-forming agent is cancelled:

[0052] The ordinary corundum abrasive is weighed in percentage by weight: 90%, the binder is 8%, and the wetting agent is 2%;

[0053] The abrasive, wetting agent, and binder are mixed in the above proportions, and the mixed materials are placed in a molding mold. Then, they are pressed twice on an oil press at 7.5 MPa, with the first pressing being 1 / 3 of the total pressure, and the second pressing being at the total pressure, maintaining for 1 min. After pressing and molding, the concave-convex part at the upper end of the grinding wheel blank is removed, and finally the grinding wheel blank is placed in an electric furnace at 900°C for 8h, and then naturally cooled to room temperature to obtain the grinding wheel piece.

[0054] The following comparative analysis is made on Example 1, Example 2, Example 3, Example 4, Example 5, and Comparative Example 1:

[0055] Under the same parameters, the hardness, porosity, grinding wheel consumption, burn and grinding of the formed grinding wheel abrasive are compared respectively.

[0056] The hardness is detected by a sand blasting hardness detection method.

[0057] The grinding wheel consumption refers to that the abrasive on the grinding surface of the grinding wheel work layer has a grinding edge when grinding a workpiece, the edge plays a grinding role (mechanical behavior such as cutting and cutting), once the grinding edge of the abrasive is ground out by the workpiece, the grinding wheel needs to be trimmed and opened by using a diamond trimming pen, and the grinding wheel will be consumed in the trimming process, and a workpiece needs to be trimmed and consumed several times, and the process is the work layer grinding wheel consumption.

[0058] The burn detection is to observe the corrosion of the workpiece surface after acid pickling and immersion and neutralization and cleaning, and to judge the burn.

[0059] The surface scratch of the processed roll is judged by the blocking of the grinding material on the grinding surface of the grinding wheel.

[0060] Table 1 Performance comparison of grinding wheel abrasive

[0061]

[0062] As shown in the data in Table 1, the super-soft large-pore ceramic grinding wheel prepared by adding the organic composite pore-forming agent and the ceramic corundum abrasive disclosed in the application solves the problems of loose super-soft grinding wheel organization and low green strength on the basis of ensuring the super-soft work layer, simultaneously makes the grinding wheel have good machining precision for high-chromium steel rolls and high-speed steel cold rolls, and finally but equally importantly, shows good thermal conductivity, can effectively reduce the temperature of the grinding wheel itself during grinding and use, and reduces the occurrence of workpiece burn.

Claims

1. A method for preparing an ultra-soft, macro-porous ceramic grinding wheel, characterized in that, The ceramic grinding wheel is composed of working layer and non-working layer, and the working layer is composed of 80% abrasive, 9% binder, 1.5% wetting agent and 9.5% organic composite pore-forming agent; The non-working layer is composed of 81% ordinary corundum abrasive, 11% binder, 1.5% wetting agent and 6.5% organic composite pore-forming agent; The abrasive in the working layer comprises 50%-70% ordinary corundum abrasive and 30-50% ceramic corundum abrasive; The organic composite pore-forming agent is composed of refined naphthalene, dextrin powder and spherical pitch. The preparation method of the grinding wheel comprises the following steps: (1) mixing, in the working layer preparation, firstly, the ceramic corundum abrasive and the ordinary corundum abrasive are respectively poured into the counter-current mixing pot and stirred for 3 min, then the wetting agent is added and stirred for 3 min, then the binder is added and stirred for 5 min, and finally the organic composite pore-forming agent is added and stirred for 5 min; In the non-working layer preparation, firstly, the ordinary corundum abrasive is poured into the counter-current mixing pot and stirred for 3 min, then the wetting agent is added and stirred for 3 min, then the binder is added and stirred for 5 min, and finally the organic composite pore-forming agent is added and stirred for 5 min; (2) forming, firstly, the mixed raw materials in step (1) are weighed for the working layer and the non-working layer, and then are pressed into the shape of the grinding wheel on the grinding wheel forming machine at 7.5Mpa in two times, the first time is 1 / 3 of the total pressure, and the second time is the total pressure, and the pressure is maintained for 1 min to obtain the grinding wheel blank; (3) trimming, the concave-convex part on the upper end of the grinding wheel blank in step (2) is removed to the size; (4) drying, the trimmed grinding wheel blank in step (3) is placed in the kiln and heated to 110℃ for drying, and after drying for 36h, it is naturally cooled to room temperature; (5) sintering, the dried grinding wheel blank in step (4) is placed in the kiln at 900℃ and sintered for 8h to obtain the grinding wheel finished product.

2. The method of claim 1, wherein the method further comprises the step of: The refined naphthalene, dextrin powder and spherical pitch are mixed into the organic composite pore-forming agent by mechanical stirring.

3. The method of claim 1, wherein the method further comprises the step of: The wetting agent is selected from water glass and dextrin liquid. ​ 4. The method of claim 1, wherein the method further comprises the step of: The binder comprises 1-4% borosilicate, 0.2-2% lithium salt, 0.5-4% clay and 2.5-10% feldspar. ​

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