Superhard diamond grinding tool containing spherical graphite

Abstract

The invention discloses a superhard diamond grinding tool containing spherical graphite, and relates to the technical field of superhard sintered grinding tools, the superhard diamond grinding tool containing spherical graphite is composed of a base body and an abrasive material bonding layer, an abrasive material layer is sintered and fixed on the working part of the base body, the abrasive material bonding layer is composed of a superhard abrasive material and a bonding agent, the superhard abrasive is diamond or CBN or a combination of the diamond and the CBN, the binding agent is one or a combination of two of a metal binding agent, a resin binding agent and a ceramic binding agent, and at least 0.01 volume percent of spherical graphite is added into the binding agent. And fine-particle spherical graphite is added into the binding agent, so that the grinding resistance is effectively reduced, and meanwhile, the grinding efficiency of the grinding tool is improved.

Description

Technical Field

[0001] The invention relates to the technical field of superhard sintered abrasive tools, in particular to a superhard diamond abrasive tool containing spherical graphite. Background Art

[0002] Superhard diamond is a kind of superhard material that is widely used at present. It is widely used in industrial manufacturing and medical surgery. In the industrial field, superhard diamond is often used as a tool and abrasive for high-speed cutting. Superhard diamond abrasives can be divided into three categories according to the binder: metal binder, resin binder and ceramic binder.

[0003] Domestic superhard ceramic bond abrasives have developed rapidly in recent years. This is mainly due to the fact that the porosity in the ceramic bond can be adjusted to a large range, which can minimize the resistance of the mold during the actual grinding process. However, due to the excessive brittleness of the ceramic bond machine mold, when the porosity reaches a certain level, the ceramic bond itself cannot support the porosity, causing the abrasive to crack easily during the actual grinding process. In this case, the degree of reducing resistance by increasing the porosity has also reached an upper limit. This requires us to further improve the grinding effect through other methods. Many of the existing mature lubricating fillers are mostly in the shape of flakes, such as the most common graphite, hexagonal boron nitride, etc. These materials have too much destructive effect on the binder. Once added to it, the strength of the binder will be greatly reduced, resulting in a significant reduction in life.

[0004] Metal bond abrasives were developed earlier in China, and many enterprises have started to conduct relevant research work early. Many factories have developed rapidly with the support of theoretical technology. So far, metal bond grinding wheels have generally adapted to the domestic market, and many have reached the level of replacing imports. Compared with resin bond and ceramic bond, metal bond has the best strength and the best holding force for superhard abrasives. This makes the metal bond superhard abrasives have a long life, and can often process some very difficult materials, such as stone, ceramics, etc. Metal bond abrasives are very strong, which often leads to the abrasives not being sharp enough. In order to solve this problem, some non-metallic materials are usually added to improve the grinding performance. Large-grained carbon particles and flake graphite are the most common materials. Large-grained carbon particles refer to some materials such as trees and coke that have not been completely burned. The particle size of these materials is mostly between 20-80 mesh, and the particle size is very coarse. Adding them to metal bond abrasives is more of a filling volume. The particle size of flake graphite is very fine, half of which is between a few microns or tens of microns, and the lubrication performance is very good. Like other binders, adding too much fine-grained flake graphite will also damage the binder. The flake graphite will cut the binder apart, resulting in the binder being unable to completely wrap the abrasive, further resulting in a significant reduction in the life of the abrasive. Therefore, flake graphite is generally added to metal-bonded abrasives within 3 mass points. How to make metal-bonded abrasives reduce the grinding resistance while not significantly reducing the life of the abrasive within a certain range, thereby improving the grinding efficiency of the abrasive and meeting customer requirements. This is an important issue facing abrasive designers.

[0005] Domestic superhard resin bond abrasives have been developed in China for a long time. This is mainly due to the simple manufacturing process of resin bond abrasives, low equipment cost and wide use of abrasives. The vigorous development of the domestic and foreign economies has provided a large market for it. However, at present, resin abrasives are still the most widely used type of abrasives. Compared with ceramic binders and metal binders, the life of grinding wheels made of resin binders is often relatively low. The fundamental reason is that the heat resistance of resin is relatively low, and it is often carbonized during the grinding process of the abrasive, which further causes the abrasive to fall off, resulting in insufficient life of the abrasive. Therefore, in superhard resin bond abrasives, in order to improve the performance of resin bond abrasives, some fillers are often added to them. For example, the most common metal powders such as copper powder, aluminum powder, zinc powder, lead powder, tin powder, and metal oxide powders such as zinc oxide, cerium oxide, chromium oxide, and iron oxide increase the holding force of the binder on the abrasive and increase the life of the abrasive. However, relying solely on the filling of metal powders often cannot meet customer needs. In many cases, the abrasive tool needs to have a certain lubrication performance, especially for abrasive tools used for many polishing purposes. At present, in order to solve this problem, most of the materials used in China are flake graphite, hexagonal boron nitride and other flake structures, which are added to the bonded abrasive tools to improve the lubrication performance. However, in addition to improving the lubrication performance, flake graphite and hexagonal boron nitride are also inserted into the bond like blades, which seriously destroys the network adhesive structure of the resin bond, greatly reduces the strength of the resin bond, and further greatly reduces the life of the abrasive tool. Therefore, under most conditions, the amount of flake graphite added to the resin bonded abrasive tool generally does not exceed 3 volume points. If it exceeds 3 volume points, the life of the abrasive tool will be greatly reduced. How to make the resin bonded abrasive tool reduce the grinding resistance and not significantly reduce the life of the abrasive tool within a certain range, so as to improve the grinding efficiency of the abrasive tool and meet customer requirements. This is an important issue facing abrasive tool designers.

[0006] Therefore, we have conducted detailed research on the specific application of spherical graphite in superhard diamond abrasive tools. Summary of the invention

[0007] The object of the present invention is to provide a superhard diamond grinding tool containing spherical graphite to solve the problems raised by the above background technology.

[0008] To achieve the above-mentioned purpose, the present invention provides the following technical scheme: a superhard diamond abrasive tool containing spherical graphite, wherein the superhard sintered abrasive tool is composed of a substrate and an abrasive bonding layer, the working part of the substrate is sintered and fixed with an abrasive layer, and the abrasive bonding layer is composed of superhard abrasive and a binder, characterized in that: the superhard abrasive is diamond or CBN or a combination of the two, the binder is one or a combination of two of a metal binder, a resin binder, and a ceramic binder, and at least 0.2 volume percent of spherical graphite is added to the binder.

[0009] Preferably, the volume percentage of spherical graphite in the ceramic binder is 0.01-5.

[0010] Preferably, the volume percentage of spherical graphite in the metal binder is 0.01 to 30.

[0011] Preferably, the volume percentage of spherical graphite in the resin binder is 0.01 to 15.

[0012] Preferably, the volume percentage of the metal compound is 1-45.

[0013] Preferably, the spherical graphite is fine-grained spherical graphite with a median particle size D50 of 8 microns to 40 microns.

[0014] Compared with the prior art, the beneficial effects of the present invention are: by adding fine-grained spherical graphite into the binder, the grinding resistance is effectively reduced while the grinding efficiency of the grinding tool is improved.

[0015] 1. Adding spherical graphite to the two types of ceramic binders, molten ceramic binder and crystallized binder, can reduce the grinding resistance and improve the grinding efficiency of the abrasive tool without reducing the strength of the ceramic binder. This effectively solves the technical problems of the existing technology of continuously increasing the porosity or adding flaky materials to cause the binder bridge to break, thereby failing to improve the grinding effect.

[0016] 2. It can reduce the grinding resistance and improve the grinding efficiency of the abrasive tool while slightly reducing the strength of the metal bond, meeting customer needs and effectively solving the technical problem in the prior art that the addition of flake graphite, hexagonal boron nitride and other flake materials causes the metal bond to break and be destroyed, thereby greatly reducing the strength of the metal bond.

[0017] 3. It can reduce the grinding resistance and improve the grinding efficiency of the abrasive tool while slightly reducing the strength of the resin bond, meeting customer needs and effectively solving the technical problem in the prior art that the addition of flake graphite, hexagonal boron nitride and other flake materials causes the network adhesive structure of the resin bond to be destroyed, thereby greatly reducing the strength of the resin bond. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a graphite experiment curve of the ceramic binder A of Example 1 of the superhard sintered abrasive tool of the present invention; Figure 2 This is a graph showing the experimental behavior of the ceramic binder B graphite of Example 1 of the superhard sintered abrasive tool of the present invention; Figure 3 This is a graph showing the experimental results of metal bond flake graphite of superhard sintered abrasive tool Example 2 of the present invention; Figure 4This is a curve diagram of the metal bond spherical graphite test results of Example 2 of the superhard sintered abrasive tool of the present invention; Figure 5 This is a graph showing the experimental results of resin bonded flake graphite of Example 3 of the superhard sintered abrasive tool of the present invention; Figure 6 This is a graph showing the experimental results of resin bonded spherical graphite in Example 3 of the superhard sintered abrasive tool of the present invention. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Example 1 Ceramic binder technical solution There are two mainstream superhard ceramic binders on the market: one is molten ceramic binder, which is brittle, self-sharpening, sharp and easy to dissipate heat. It is usually used to process workpieces with high hardness and easy to burn. The sintering temperature of this type of binder is usually between 600℃ and 800℃. The binder code of our experiment is A, and its main components are as follows: Table 1 Main components of fused vitrified binder A ingredient percentage Silicon dioxide 60 Boron trioxide 12 Calcium Oxide 11 Sodium oxide 6 Alumina 5 Lithium Oxide 4 Barium Oxide 3 other 3 Another mainstream superhard ceramic binder on the market is the crystallized binder. This type of binder has an additional heat preservation and crystallization process during the production process or during the firing of the abrasive tool, which produces grains in the binder. The size of the grains is mostly below 5 microns. With these fine grains, the hardness of the binder is very high, and the thermal expansion coefficient is often small. This type of binder is often used for high-grade superhard abrasive tools. The sintering temperature of this type of binder is often between 650℃ and 920℃. The binder code for this experiment is B, and its main components are shown in Table 2: Table 2 Main components of crystallized ceramic binder B ingredient percentage Silicon dioxide 62 Alumina 17 Potassium Oxide 9 Calcium Oxide 4 Sodium oxide 2 Barium Oxide 2 Magnesium Oxide 1 other 3 In order to test the effect of spherical graphite, we added spherical graphite to the two most commonly used ceramic binders on the market to observe the effects.

[0021] Table 3 Basic scheme of ceramic binder Material Name Volume ratio Diamond 30 Low temperature ceramic binder 25 Porosity 45 Based on the basic scheme in Table 3, diamond grinding wheels were made using two binders A and B and tested.

[0022] Different amounts of spherical graphite (D50: 11 microns) were added on the basis of Table 3, and the grinding resistance and grinding wheel loss were measured. Table 4 shows the experimental results of the resistance and grinding wheel loss of the A binder scheme after adding spherical graphite.

[0023] Table 4 Resistance and grinding wheel loss of A binder scheme after adding spherical graphite serial number plan Resistance (N) Grinding wheel loss (UM) A1 Basic plan A (control group) 120 20 A2 Basic solution + 0.2 volume spherical graphite 102 21 A3 Basic solution + 0.75 volume spherical graphite 99 23 A4 Basic solution + 1.0 volume spherical graphite 98 26 A5 Basic solution + 1.5 volume spherical graphite 95 30 A6 Basic plan + 2.0 volume spherical graphite 90 35 A7 Basic plan + 4.0 volume spherical graphite 85 45 A8 Basic plan + 6.0 volume spherical graphite 80 55 A9 Basic plan + 10.0 volume spherical graphite 56 100 Table 5 shows the experimental results of resistance and grinding wheel loss of B binder solution after adding spherical graphite.

[0024] Table 5 Statistical table of experimental results of B binder solution serial number plan Resistance (N) Grinding wheel loss (UM) B1 Basic plan B (control group) 135 18 B2 Basic solution + 0.2 volume spherical graphite 124 19 B3 Basic solution + 0.75 volume spherical graphite 118 21 B4 Basic solution + 1.0 volume spherical graphite 105 24 B5 Basic solution + 1.5 volume spherical graphite 99 29 B6 Basic plan + 2.0 volume spherical graphite 95 33 B7 Basic plan + 4.0 volume spherical graphite 88 41 B8 Basic plan + 6.0 volume spherical graphite 83 52 B9 Basic plan + 10.0 volume spherical graphite 62 96 From the experimental data in Table 4, we can get Figure 1 The experimental results curve graph.

[0025] From the experimental results in Table 5, we can get Figure 2 The experimental results curve graph.

[0026] from Figure 1 and Figure 2 It can be clearly seen that, whether it is molten binder A or crystallized binder B, adding spherical graphite can significantly reduce the grinding resistance of superhard abrasive tools. Compared with the basic scheme of the control group, only 0.2 volume of spherical graphite needs to be added to reduce the resistance to about 15%, which can significantly improve the grinding effect of the grinding wheel. When the volume ratio of spherical graphite is within 6 points, the loss of the grinding wheel increases slowly and the resistance is also decreasing. When the volume of spherical graphite reaches more than 6 points, although the resistance of the grinding wheel is decreasing, the loss of the grinding wheel increases significantly, which will greatly reduce the cost performance of the grinding wheel. After optimization experiments, it is found that the ideal state is to add within 0.01~5 volume points.

[0027] Example 2 Metal binder technical solution There are many types of mainstream metal binders on the market, such as copper-based binders, iron-based binders, cobalt-based binders, silver-based binders, nickel-based binders, etc. Among them, cobalt-, silver-, and nickel-based binders are expensive and not widely used in the market. Copper- and iron-based binders are widely used, especially cobalt-based binders, which are the most widely used type.

[0028] Regardless of whether it is a copper, iron-based binder or a nickel, cobalt, or silver-based binder, their usual bonding strength is above 700MPa. This strength is usually too high, and the super-hard abrasive is held too strongly, resulting in the inability to fully expose the cutting edge of the abrasive, causing blockage, and insufficient sharpness of the abrasive, which requires constant dressing, which not only wastes a lot of manpower, but also reduces the life of the abrasive.

[0029] In view of this, we chose the copper-based binder with the largest usage in the market as the test object.

[0030] Table 6 Basic scheme of metal binder Material Name Quality Ratio Diamond 5 Metal binder 95 The metal binder is copper-tin alloy powder, and the sintering temperature is 780 degrees.

[0031] For the convenience of comparison, we first add graphite flakes to the basic scheme as a comparison group. According to the normal process of metal bond abrasives, the end grinding wheel is made with an outer diameter of 250mm, a thickness of 40mm, an inner hole of 180mm, and a particle size of 100. The processing object is ceramics.

[0032] For the convenience of distinction, the reference control group is numbered 0, the ones with added flake graphite are numbered C, and the ones with added spherical graphite are numbered D. The test results are shown in Tables 6 and 7.

[0033] Table 6 Experimental scheme for flake graphite serial number plan Resistance (N) Grinding wheel loss (UM) C0 Basic plan (control group) 78 53 C 1 Basic solution + 0.01 volume flake graphite 61 51 C 2 Basic solution + 0.02 volume flake graphite 46 48 C 3 Basic solution + 0.1 volume flake graphite 42 49 C 4 Basic plan + 1 volume of flake graphite 36 55 C 5 Basic plan + 5 volumes of flake graphite 25 73 C 6 Basic plan + 10 volumes of flake graphite 18 94 C 7 Basic plan + 15 volumes of flake graphite 17 186 C 8 Basic plan + 20 volumes of flake graphite 16 398 From the data in Table 6, we get Figure 3 Graph of experimental results for flake graphite.

[0034] Table 7 Spherical graphite experimental plan serial number plan Resistance (N) Grinding wheel loss (UM) D0 Basic plan (control group) 78 53 D1 Basic solution + 0.01 volume spherical graphite 62 51 D2 Basic solution + 0.02 volume spherical graphite 47 49 D3 Basic solution + 0.1 volume spherical graphite 43 50 D4 Basic solution + 1 volume of spherical graphite 41 49 D5 Basic plan + 5 volumes of spherical graphite 38 51 D6 Basic plan + 10 volumes of spherical graphite 34 64 D7 Basic plan + 15 volumes of spherical graphite 29 79 D8 Basic plan + 20 volumes of spherical graphite 25 91 D9 Basic plan + 25 volume spherical graphite 20 95 D10 Basic plan + 30 volumes of spherical graphite 16 100 D11 Basic plan + 35 volume spherical graphite 15 200 Similarly, through the data in Table 7, we get Figure 4 Graph of experimental results of spherical graphite.

[0035] Depend on Figure 3 We can see that when adding flake graphite to the basic solution, the grinding resistance drops very quickly. When 10 volume points of flake graphite are added, the grinding wheel consumption reaches 94um, which is 77.35% higher than the basic solution; when 15 volume points of flake graphite are added, the grinding wheel consumption reaches 186um, which is 250.09% higher than the basic solution, which is often unacceptable to customers. Therefore, the amount of flake graphite added is generally within 10 volume points. If 10 volume points of flake graphite are converted into mass points, it is around 3 mass points.

[0036] pass Figure 4From the test data, we can see that when spherical graphite is added to the basic solution, the grinding resistance decreases at a relatively slow rate, and the loss of the grinding wheel is also slowly decreasing. When 20 volume points of spherical graphite are added, the grinding wheel consumption is 91um, which is equivalent to adding 10 volume points of flake graphite to the basic solution. When 30 volume points of spherical graphite are added, the grinding wheel consumption is 100um, which is also equivalent to adding 10 volume points of flake graphite to the basic solution. When 35 volume points of spherical graphite are added, the grinding wheel consumption is 200um, and the loss increases significantly. This shows that the loss will only increase significantly when the volume of spherical graphite exceeds 30 points.

[0037] The addition of spherical graphite does not cause obvious damage to the binder like flake graphite. The decrease in resistance and the increase in grinding loss increase slowly, indicating that spherical graphite is more like a lubricating filler and has a lower degree of damage to the binder. When the volume ratio of spherical graphite is within 30 points, the loss of the grinding wheel increases slowly and the resistance is also decreasing. When the volume of spherical graphite reaches more than 30 points, the resistance of the grinding wheel decreases, but the loss of the grinding wheel increases significantly. Therefore, the ideal state is to add 0~30 volume points. If 30 volume points of spherical graphite are converted into mass points, it is about 9 mass points.

[0038] To sum up, spherical graphite can be added to the metal binder at 0-30 volume points.

[0039] Example 3 Resin binder technical solution There are two mainstream resins used in super-hard abrasives on the market: one is phenolic resin powder, which has a low curing temperature, generally around 180 degrees, and poor high temperature resistance, and is generally only used for wet grinding. The other is bismaleimide resin powder, which has a higher sintering temperature than phenolic resin powder, generally around 230 degrees, and has better high temperature resistance than phenolic resin, and is more versatile for dry and wet grinding.

[0040] Based on versatility considerations, we used bismaleimide resin powder in this test.

[0041] Table 8 Basic scheme of bismaleimide resin binder Material volume Diamond D / NI56 38 MBI Polyimide Resin Powder 48 Copper powder Cu 14 For the convenience of comparison, we first added graphite flakes to the basic solution as a comparison group. According to the normal resin process, a parallel grinding wheel with an outer diameter of 180mm, a thickness of 12mm, an inner hole of 31.75mm, and a particle size of 150 was made. It was tested on a surface grinder, and the processing object was cemented carbide.

[0042] For the convenience of distinction, the reference control group is numbered 0, the ones with added flake graphite are numbered E, and the ones with added spherical graphite are numbered F. The test results are shown in Tables 9 and 10 below.

[0043] Table 9 Resin control group and flake graphite addition scheme serial number plan Resistance (N) Grinding wheel loss (UM) E0 Basic plan (control group) 146 16 E1 Basic Plan 99+1 Volumetric Flake Graphite 121 19 E2 Basic solution 97+3 volume flake graphite 95 27 E3 Basic solution 95+5 volume flake graphite 76 98 E4 Basic solution 93+7 volume flake graphite 26 298 Table 10 Resin control group and spherical graphite addition scheme serial number plan Resistance (N) Grinding wheel loss (UM) F0 Basic plan (control group) 146 16 F1 Basic solution 99+1 volume spherical graphite 132 17 F2 Basic solution 97+3 volume spherical graphite 127 20 F3 Basic solution 95+5 volume spherical graphite 123 23 F4 Basic solution 93+7 volume spherical graphite 118 27 F5 Basic scheme 91+9 volume spherical graphite 112 32 F6 Basic scheme 89+11 volume spherical graphite 104 38 F7 Basic solution 87+13 volume spherical graphite 94 45 F8 Basic solution 85+15 volume spherical graphite 82 52 F9 Basic solution 80+20 volume spherical graphite 58 98 F10 Basic solution 75+25 volume spherical graphite 39 135 F11 Basic solution 70+30 volume spherical graphite 29 365 The corresponding experimental result curves are obtained from Tables 9 and 10, see Figure 5 and Figure 6 .

[0044] pass Figure 5 We can clearly see that when flake graphite is added to the basic solution, the grinding resistance decreases very quickly. When more than 3 volume points of flake graphite are added, the grinding wheel consumption increases directly from 27um to 98um, and the loss increases by more than 3 times, which is often unacceptable to customers.

[0045] pass Figure 6 , we can clearly see that when spherical graphite is added to the basic solution, the grinding resistance decreases slowly, and the loss of the grinding wheel is also slowly decreasing. When 20 volume points of spherical graphite are added, the grinding wheel consumption reaches 98um, which is equivalent to adding 5 volume points of flake graphite to the basic solution, but the resistance is still lower than that of flake graphite. The addition of spherical graphite does not significantly damage the binder like flake graphite. The decrease in resistance and the increase in grinding loss increase slowly, indicating that spherical graphite is more like a lubricating filler and has a lower degree of damage to the binder. When the volume ratio of spherical graphite is within 15 points, the loss of the grinding wheel increases slowly, and the resistance is also decreasing. When the volume of spherical graphite reaches more than 15 points, although the grinding wheel resistance is decreasing, the grinding wheel loss increases significantly. Therefore, the ideal state is to add within 0~15 volume points.

[0046] To sum up, spherical graphite can be added to the resin binder at 0-15 volume points.

[0047] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A superhard diamond grinding tool containing spherical graphite, the superhard sintered grinding tool is composed of a substrate and an abrasive bonding layer, the working part of the substrate is sintered and fixed with an abrasive layer, and the abrasive bonding layer is composed of superhard abrasive and a binder, characterized in that: The super-hard abrasive is diamond or CBN or a combination of the two, the binder is one or a combination of metal binder, resin binder, ceramic binder, and at least 0.01 volume percent of spherical graphite is added to the binder.

2. The superhard diamond grinding tool containing spherical graphite according to claim 1, characterized in that: The volume percentage of spherical graphite in the ceramic binder is 0.01-5.

3. The superhard diamond grinding tool containing spherical graphite according to claim 1, characterized in that: The volume percentage of spherical graphite in the metal binder is 0.01-30.

4. The superhard diamond grinding tool containing spherical graphite according to claim 1, characterized in that: The volume percentage of spherical graphite in the resin binder is 0.01-15.

5. The superhard diamond grinding tool containing spherical graphite according to any one of claims 2 to 4, characterized in that: The spherical graphite is fine-grained spherical graphite with a median particle size D50 of 8 microns to 40 microns.

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